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Kvalnes T, Flagstad Ø, Våge J, Strand O, Viljugrein H, Sæther B. Harvest and decimation affect genetic drift and the effective population size in wild reindeer. Evol Appl 2024; 17:e13684. [PMID: 38617828 PMCID: PMC11009432 DOI: 10.1111/eva.13684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/29/2024] [Accepted: 03/13/2024] [Indexed: 04/16/2024] Open
Abstract
Harvesting and culling are methods used to monitor and manage wildlife diseases. An important consequence of these practices is a change in the genetic dynamics of affected populations that may threaten their long-term viability. The effective population size (N e) is a fundamental parameter for describing such changes as it determines the amount of genetic drift in a population. Here, we estimate N e of a harvested wild reindeer population in Norway. Then we use simulations to investigate the genetic consequences of management efforts for handling a recent spread of chronic wasting disease, including increased adult male harvest and population decimation. The N e/N ratio in this population was found to be 0.124 at the end of the study period, compared to 0.239 in the preceding 14 years period. The difference was caused by increased harvest rates with a high proportion of adult males (older than 2.5 years) being shot (15.2% in 2005-2018 and 44.8% in 2021). Increased harvest rates decreased N e in the simulations, but less sex biased harvest strategies had a lower negative impact. For harvest strategies that yield stable population dynamics, shifting the harvest from calves to adult males and females increased N e. Population decimation always resulted in decreased genetic variation in the population, with higher loss of heterozygosity and rare alleles with more severe decimation or longer periods of low population size. A very high proportion of males in the harvest had the most severe consequences for the loss of genetic variation. This study clearly shows how the effects of harvest strategies and changes in population size interact to determine the genetic drift of a managed population. The long-term genetic viability of wildlife populations subject to a disease will also depend on population impacts of the disease and how these interact with management actions.
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Affiliation(s)
- Thomas Kvalnes
- Norwegian Institute for Nature Research (NINA)TrondheimNorway
- Centre for Biodiversity Dynamics (CBD), Department of BiologyNorwegian University of Science and Technology (NTNU)TrondheimNorway
| | | | - Jørn Våge
- Norwegian Veterinary InstituteÅsNorway
| | - Olav Strand
- Norwegian Institute for Nature Research (NINA)TrondheimNorway
| | | | - Bernt‐Erik Sæther
- Centre for Biodiversity Dynamics (CBD), Department of BiologyNorwegian University of Science and Technology (NTNU)TrondheimNorway
- Gjærevoll Center for Biodiversity Foresight AnalysesNorwegian University of Science and Technology (NTNU)TrondheimNorway
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2
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Luzzatto D, Cussac V. A novel non-invasive efficient photography-based technique for length measuring and individual identification of seahorses. Sci Rep 2023; 13:18017. [PMID: 37865693 PMCID: PMC10590381 DOI: 10.1038/s41598-023-45420-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 10/19/2023] [Indexed: 10/23/2023] Open
Abstract
This study aimed to develop a non-invasive and efficient method for measuring and identifying individual seahorses (Hippocampus patagonicus) in their natural habitat. A total of 976 seahorses were captured and photographed on a measuring board to obtain standard length (Ls) measurements. Head photographs were also taken for individual recognition, and a set of 100 seahorses were tagged with visible implant elastomers (VIE) to verify the correspondence between photograph recognition and the applied tags. The analysis showed no significant difference between left and right Ls measurements. The unique pattern of white dots on the heads served as individual fingerprints, consistent with VIE tagging. The recapture rate was 12%, with 89 individuals observed multiple times. Two distinct growth patterns were identified: males exhibited higher growth rates and a negative correlation with Ls compared to females. Released seahorses exhibited significantly different behaviors that were related to their sizes (Ls). Smaller seahorses tended to swim slowly towards nearby holdfasts, while larger seahorses escaped further or remained rigid before grasping a holdfast. The proposed methodology allowed for estimating individual seahorse growth rates, and the measurements were objective and precise. The results were obtained through quick and minimally invasive manipulation of the observed individuals.
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Affiliation(s)
- Diego Luzzatto
- Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales (IPATEC), Universidad Nacional del Comahue (UNCo) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), R8400, Bariloche, Argentina.
- Seahorse, Pipefish and Seadragon Specialist Group, IUCN Species Survival Commission, Rue Mauverney 28, 1196, Gland, Switzerland.
| | - Victor Cussac
- Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales (IPATEC), Universidad Nacional del Comahue (UNCo) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), R8400, Bariloche, Argentina
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3
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Kvistad JT, Galarowicz TL, Clapp DF, Chadderton WL, Tucker AJ, Annis G, Herbert M. Evidence of a compensatory response in invasive Rusty Crayfish ( Faxonius rusticus) following intensive harvest removal from northern Lake Michigan fish spawning reefs. Biol Invasions 2023; 25:1-17. [PMID: 37362907 PMCID: PMC10166462 DOI: 10.1007/s10530-023-03076-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 04/25/2023] [Indexed: 06/28/2023]
Abstract
The goal of most invasive species suppression programs is to achieve long-term sustained reductions in population abundance, yet removal programs can be stymied by density-dependent population responses. We tested a harvest removal strategy for invasive Rusty Crayfish (Faxonius rusticus) at two nearshore native fish spawning habitats in northern Lake Michigan. Changes in average Rusty Crayfish densities were evaluated with a before-after reference-impact study design. We removed 3182 Rusty Crayfish, primarily adults (> 20 mm carapace length), at two sites over two harvest seasons, expending 17,825 trap days in effort. Generalized linear modeling results suggested a statistically significant reduction in Rusty Crayfish densities was achieved at one reef, Little Traverse Bay (LTB Crib). Reduced densities were sustained over the egg maturation period for native fish and into the following year after removal ceased. By late summer/early fall, between consecutive suppression efforts in 2018 and 2019, we observed a threefold increase in pre-removal densities. Size-frequency histograms from diver quadrat surveys showed higher abundances of juvenile (< 20 mm carapace length) size classes the following spring and summer at LTB Crib compared to its paired reference site. Stock-recruit curves fit to count data, pooled across all sites, provided further evidence of density-dependence. With a proviso that we only conducted two seasons of consecutive suppression, this study highlights an important aspect of invasive species management and raises questions about the efficacy of adult-only crayfish removal strategies. Supplementary Information The online version contains supplementary material available at 10.1007/s10530-023-03076-6.
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Affiliation(s)
- Jake T. Kvistad
- Department of Biology, Biosciences 2100, Central Michigan University, Mount Pleasant, MI 48859 USA
- Cramer Fish Sciences, Watershed Sciences Laboratory, 1125 12th Avenue NW, Suite B-1, Issaquah, WA 98027 USA
| | - Tracy L. Galarowicz
- Department of Biology, Biosciences 2100, Central Michigan University, Mount Pleasant, MI 48859 USA
| | - David F. Clapp
- Michigan Department of Natural Resources, Charlevoix Fisheries Research Station, 96 Grant Street, Charlevoix, MI 49720 USA
| | - William L. Chadderton
- The Nature Conservancy, 721 Flanner Hall, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Andrew J. Tucker
- The Nature Conservancy, 721 Flanner Hall, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Gust Annis
- The Nature Conservancy, 101 E. César E. Chávez Avenue, Lansing, MI 48906 USA
| | - Matthew Herbert
- The Nature Conservancy, 101 E. César E. Chávez Avenue, Lansing, MI 48906 USA
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4
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Sorel MH, Murdoch AR, Zabel RW, Kamphaus CM, Buhle ER, Scheuerell MD, Converse SJ. Effects of population density and environmental conditions on life-history prevalence in a migratory fish. Ecol Evol 2023; 13:e10087. [PMID: 37234292 PMCID: PMC10206029 DOI: 10.1002/ece3.10087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/28/2023] [Accepted: 04/26/2023] [Indexed: 05/27/2023] Open
Abstract
Individual variation in life-history traits can have important implications for the ability of populations to respond to environmental variability and change. In migratory animals, flexibility in the timing of life-history events, such as juvenile emigration from natal areas, can influence the effects of population density and environmental conditions on habitat use and population dynamics. We evaluated the functional relationships between population density and environmental covariates and the abundance of juveniles expressing different life-history pathways in a migratory fish, Chinook salmon (Oncorhynchus tshawytscha), in the Wenatchee River basin in Washington State, USA. We found that the abundance of younger emigrants from natal streams was best described by an accelerating or near-linear function of spawners, whereas the abundance of older emigrants was best described by a decelerating function of spawners. This supports the hypothesis that emigration timing varies in response to density in natal areas, with younger-emigrating life-history pathways comprising a larger proportion of emigrants when densities of conspecifics are high. We also observed positive relationships between winter stream discharge and abundance of younger emigrants, supporting the hypothesis that habitat conditions can also influence the prevalence of different life-history pathways. Our results suggest that early emigration, and a resultant increase in the use of downstream rearing habitats, may increase at higher population densities and with greater winter precipitation. Winter precipitation is projected to increase in this system due to climate warming. Characterizing relationships between life-history prevalence and environmental conditions may improve our understanding of species habitat requirements and is a first step in understanding the dynamics of species with diverse life-history strategies. As environmental conditions change-due to climate change, management, or other factors-resultant life-history changes are likely to have important demographic implications that will be challenging to predict when life-history diversity is not accounted for in population models.
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Affiliation(s)
- Mark H. Sorel
- Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA
| | | | - Richard W. Zabel
- Northwest Fisheries Science Center, National Marine Fisheries ServiceNational Oceanic and Atmospheric AssociationSeattleWashingtonUSA
| | | | - Eric R. Buhle
- Northwest Fisheries Science Center, National Marine Fisheries ServiceNational Oceanic and Atmospheric AssociationSeattleWashingtonUSA
- Mt. Hood EnvironmentalSandyOregonUSA
| | - Mark D. Scheuerell
- U.S. Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA
| | - Sarah J. Converse
- U.S. Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences & School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA
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5
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Boscari E, Wu J, Jiang T, Zhang S, Cattelan S, Wang C, Du H, Li C, Li J, Ruan R, Xu J, Zheng Y, Palle SD, Yang J, Congiu L, Wei Q. The last giants of the Yangtze River: A multidisciplinary picture of what remains of the endemic Chinese sturgeon. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 843:157011. [PMID: 35772549 DOI: 10.1016/j.scitotenv.2022.157011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/09/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
The Chinese sturgeon, an important endemism of the Yangtze River, belongs to 'the most critically endangered group of species' worldwide, with overfishing and habitat destruction being the main drivers towards extinction. Newly obtained microchemical comparisons between animals and water from different river locations revealed a probable shifting of the spawning ground few kilometers downstream compared to the only previously known site, located under the Gezhouba Dam. This offers a glimmer of hope for an adaptive response to habitat perturbation caused by the recently built Three Gorges dam on the Yangtze River. On the other hand, genetic data provide an estimate of about 20 breeders participating in the only significant breeding event of the past 10 years. This warns of a near species extinction forecast if no in situ and ex situ conservation efforts occur promptly. Given these results we propose a list of priority conservation actions that urgently need to be promoted, supported, and put into practice.
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Affiliation(s)
- Elisa Boscari
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; Ecology Research Unit, Department of Biology, University of Padua, Padova 35131, Italy
| | - Jinming Wu
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Tao Jiang
- Key Laboratory of Fishery Ecological Environment Assessment and Resource Conservation in Middle and Lower Reaches of the Yangtze River, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi City, Jiangsu Province 214081, China
| | - Shuhuan Zhang
- Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
| | - Silvia Cattelan
- Ecology Research Unit, Department of Biology, University of Padua, Padova 35131, Italy
| | - Chengyou Wang
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Hao Du
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Chuangju Li
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Junyi Li
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Rui Ruan
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Junmin Xu
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China
| | - Yueping Zheng
- Shanghai Aquatic Wildlife Conservation and Research Center, Chongming, Shanghai 200003, China
| | - Stefano Dalle Palle
- Ecology Research Unit, Department of Biology, University of Padua, Padova 35131, Italy
| | - Jian Yang
- Key Laboratory of Fishery Ecological Environment Assessment and Resource Conservation in Middle and Lower Reaches of the Yangtze River, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi City, Jiangsu Province 214081, China
| | - Leonardo Congiu
- Ecology Research Unit, Department of Biology, University of Padua, Padova 35131, Italy.
| | - Qiwei Wei
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China; Guizhou University of Traditional Chinese Medicine, Guiyang 550025, China
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6
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Tirronen M, Perälä T, Kuparinen A. Temporary Allee effects among non-stationary recruitment dynamics in depleted gadid and flatfish populations. FISH AND FISHERIES (OXFORD, ENGLAND) 2022; 23:392-406. [PMID: 35875511 PMCID: PMC9298083 DOI: 10.1111/faf.12623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 09/28/2021] [Accepted: 10/05/2021] [Indexed: 06/15/2023]
Abstract
Many considerably declined fish populations have not fully recovered despite reductions in fishing pressure. One of the possible causes of impaired recovery is the (demographic) Allee effect. To investigate whether low-abundance recruitment dynamics can switch between compensation and depensation, the latter implying the presence of the Allee effect, we analysed the stock-recruitment time series of 17 depleted cod-type and flatfish populations using a Bayesian change point model. The recruitment dynamics were represented with the sigmoidal Beverton-Holt and the Saila-Lorda stock-recruitment models, allowing the parameters of the models to shift at a priori unknown change points. Our synthesis study questions the common assumption that recruitment is stationary and compensatory and the high amount of scatteredness often present in stock-recruitment data is only due to random variation. When a moderate amount of such variation was assumed, stock-recruitment dynamics were best explained by a non-stationary model for 53% of the populations, which suggests that these populations exhibit temporal changes in the stock-recruitment relationship. For four populations, we found shifts between compensation and depensation, suggesting the presence of temporary Allee effects. However, the evidence of Allee effects was highly dependent on the priors of the stock-recruitment model parameters and the amount of random variation assumed. Nonetheless, detection of changes in low-abundance recruitment is essential in stock assessment since such changes affect the renewal ability of the population and, ultimately, its sustainable harvest limits.
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Affiliation(s)
- Maria Tirronen
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Tommi Perälä
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Anna Kuparinen
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
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7
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Perälä T, Hutchings JA, Kuparinen A. Allee effects and the Allee-effect zone in northwest Atlantic cod. Biol Lett 2022; 18:20210439. [PMID: 35104425 PMCID: PMC8807053 DOI: 10.1098/rsbl.2021.0439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 12/14/2021] [Indexed: 01/05/2023] Open
Abstract
According to the theory of compensatory dynamics, depleted populations should recover when the threat responsible for their decline is removed because per capita population growth is assumed to be highest when populations are at their smallest viable sizes. Yet, many seriously depleted fish populations have failed to recover despite threat mitigation. Atlantic cod (Gadus morhua) stocks off Newfoundland, despite 30 years of dramatically reduced fishing mortality and numerous fishery closures, have not recovered, suggesting that drivers other than fishing can regulate the growth of collapsed fish populations, inhibiting or preventing their recovery. Here, using Bayesian inference, we show strong evidence of Allee effects in a south Newfoundland cod population, based on data on recruitment and spawning stock biomass. We infer the Allee-effect threshold, below which recovery is impaired. We demonstrate the necessity of data at low population sizes to make inferences about the nature of low-abundance dynamics. Our work indicates that Allee effects are not negligible in commercially exploited fish populations, as commonly projected, and that they represent an inhibitory force that can effectively prevent recovery from overfishing. Our findings contrast with prevailing fisheries management practices that assume compensatory dynamics at low abundances with potential to seriously overestimate the recovery potential of collapsed populations.
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Affiliation(s)
- Tommi Perälä
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40014, Finland
| | - Jeffrey A. Hutchings
- Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada B3H 4R2
- Institute of Marine Research, Flødevigen Marine Research Station, N-4817 His, Norway
- Department of Natural Sciences, University of Agder, N-4604 Kristiansand, Norway
| | - Anna Kuparinen
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40014, Finland
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8
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Marjomäki TJ, Valkeajärvi P, Karjalainen J. Lifting the Vendace, Coregonus albula, on the Life Table: Survival, Growth and Reproduction in Different Life-Stages during Very High and Low Abundance Regimes. ANN ZOOL FENN 2021. [DOI: 10.5735/086.058.0406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Timo J. Marjomäki
- Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
| | - Pentti Valkeajärvi
- Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
| | - Juha Karjalainen
- Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
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9
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Novel robust time series analysis for long-term and short-term prediction. Sci Rep 2021; 11:11938. [PMID: 34099758 PMCID: PMC8184922 DOI: 10.1038/s41598-021-91327-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 05/24/2021] [Indexed: 11/30/2022] Open
Abstract
Nonlinear phenomena are universal in ecology. However, their inference and prediction are generally difficult because of autocorrelation and outliers. A traditional least squares method for parameter estimation is capable of improving short-term prediction by estimating autocorrelation, whereas it has weakness to outliers and consequently worse long-term prediction. In contrast, a traditional robust regression approach, such as the least absolute deviations method, alleviates the influence of outliers and has potentially better long-term prediction, whereas it makes accurately estimating autocorrelation difficult and possibly leads to worse short-term prediction. We propose a new robust regression approach that estimates autocorrelation accurately and reduces the influence of outliers. We then compare the new method with the conventional least squares and least absolute deviations methods by using simulated data and real ecological data. Simulations and analysis of real data demonstrate that the new method generally has better long-term and short-term prediction ability for nonlinear estimation problems using spawner–recruitment data. The new method provides nearly unbiased autocorrelation even for highly contaminated simulated data with extreme outliers, whereas other methods fail to estimate autocorrelation accurately.
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10
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Sarkar S, Narang A, Sinha SK, Dutta PS. Effects of stochasticity and social norms on complex dynamics of fisheries. Phys Rev E 2021; 103:022401. [PMID: 33735958 DOI: 10.1103/physreve.103.022401] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 01/22/2021] [Indexed: 11/07/2022]
Abstract
Recreational fishing is a highly socioecological process. Although recreational fisheries are self-regulating and resilient, changing anthropogenic pressure drives these fisheries to overharvest and collapse. Here, we evaluate the effect of demographic and environmental stochasticity for a social-ecological two-species fish model. In the presence of noise, we find that an increase in harvesting rate drives a critical transition from high-yield-low-price fisheries to low-yield-high-price fisheries. To calculate stochastic trajectories for demographic noise, we derive the master equation corresponding to the model and perform a Monte Carlo simulation. Moreover, the analysis of the probabilistic potential and mean first-passage time reveals the resilience of alternative steady states. We also describe the efficacy of a few generic indicators in forecasting sudden transitions. Furthermore, we show that incorporating social norms on the model allows a moderate fish density to maintain despite higher harvesting rates. Overall, our study highlights the occurrence of critical transitions in a stochastic social-ecological model and suggests ways to mitigate them.
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Affiliation(s)
- Sukanta Sarkar
- Department of Mathematics, Indian Institute of Technology Ropar, Punjab, India
| | - Arzoo Narang
- Department of Mathematics, Indian Institute of Technology Ropar, Punjab, India
| | - Sudipta Kumar Sinha
- Department of Chemistry, Indian Institute of Technology Ropar, Punjab, India
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11
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Cooke SJ, Venturelli P, Twardek WM, Lennox RJ, Brownscombe JW, Skov C, Hyder K, Suski CD, Diggles BK, Arlinghaus R, Danylchuk AJ. Technological innovations in the recreational fishing sector: implications for fisheries management and policy. REVIEWS IN FISH BIOLOGY AND FISHERIES 2021. [PMID: 33642705 DOI: 10.1007/s1160-021-09643-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Technology that is developed for or adopted by the recreational fisheries sector (e.g., anglers and the recreational fishing industry) has led to rapid and dramatic changes in how recreational anglers interact with fisheries resources. From improvements in finding and catching fish to emulating their natural prey and accessing previously inaccessible waters, to anglers sharing their exploits with others, technology is completely changing all aspects of recreational fishing. These innovations would superficially be viewed as positive from the perspective of the angler (aside from the financial cost of purchasing some technologies), yet for the fisheries manager and policy maker, technology may create unintended challenges that lead to reactionary or even ill-defined approaches as they attempt to keep up with these changes. The goal of this paper is to consider how innovations in recreational fishing are changing the way that anglers interact with fish, and thus how recreational fisheries management is undertaken. We use a combination of structured reviews and expert analyses combined with descriptive case studies to highlight the many ways that technology is influencing recreational fishing practice, and, relatedly, what it means for changing how fisheries and/or these technologies need to be managed-from changes in fish capture, to fish handling, to how anglers share information with each other and with managers. Given that technology is continually evolving, we hope that the examples provided here lead to more and better monitoring of technological innovations and engagement by the management and policy authorities with the recreational fishing sector. Doing so will ensure that management actions related to emerging and evolving recreational fishing technology are more proactive than reactive.
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Affiliation(s)
- Steven J Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6 Canada
| | - Paul Venturelli
- Department of Biology, Ball State University, Cooper Life Science Building, CL 121, Muncie, IN 47306 USA
| | - William M Twardek
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6 Canada
| | - Robert J Lennox
- LFI, Freshwater Biology, NORCE Norwegian Research Centre, Nygårdsporten 112, 5006 Bergen, Norway
| | - Jacob W Brownscombe
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6 Canada
- Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, 867 Lakeshore Rd, Burlington, ON L7S 1A1 Canada
| | - Christian Skov
- Technical University of Denmark, National Institute of Aquatic Resources (DTU Aqua), Vejlsøvej 39, 8600 Silkeborg, Denmark
| | - Kieran Hyder
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Pakefield Road, Lowestoft, Suffolk, NR33 0HT UK
| | - Cory D Suski
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave, Urbana, IL 61801 USA
| | | | - Robert Arlinghaus
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany
- Division of Integrative Fisheries Management, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
| | - Andy J Danylchuk
- Department of Environmental Conservation, University of Massachusetts Amherst, 160 Holdsworth Way, Amherst, MA 01003 USA
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12
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Cooke SJ, Venturelli P, Twardek WM, Lennox RJ, Brownscombe JW, Skov C, Hyder K, Suski CD, Diggles BK, Arlinghaus R, Danylchuk AJ. Technological innovations in the recreational fishing sector: implications for fisheries management and policy. REVIEWS IN FISH BIOLOGY AND FISHERIES 2021; 31:253-288. [PMID: 33642705 PMCID: PMC7900803 DOI: 10.1007/s11160-021-09643-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 02/02/2021] [Indexed: 05/13/2023]
Abstract
Technology that is developed for or adopted by the recreational fisheries sector (e.g., anglers and the recreational fishing industry) has led to rapid and dramatic changes in how recreational anglers interact with fisheries resources. From improvements in finding and catching fish to emulating their natural prey and accessing previously inaccessible waters, to anglers sharing their exploits with others, technology is completely changing all aspects of recreational fishing. These innovations would superficially be viewed as positive from the perspective of the angler (aside from the financial cost of purchasing some technologies), yet for the fisheries manager and policy maker, technology may create unintended challenges that lead to reactionary or even ill-defined approaches as they attempt to keep up with these changes. The goal of this paper is to consider how innovations in recreational fishing are changing the way that anglers interact with fish, and thus how recreational fisheries management is undertaken. We use a combination of structured reviews and expert analyses combined with descriptive case studies to highlight the many ways that technology is influencing recreational fishing practice, and, relatedly, what it means for changing how fisheries and/or these technologies need to be managed-from changes in fish capture, to fish handling, to how anglers share information with each other and with managers. Given that technology is continually evolving, we hope that the examples provided here lead to more and better monitoring of technological innovations and engagement by the management and policy authorities with the recreational fishing sector. Doing so will ensure that management actions related to emerging and evolving recreational fishing technology are more proactive than reactive.
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Affiliation(s)
- Steven J. Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6 Canada
| | - Paul Venturelli
- Department of Biology, Ball State University, Cooper Life Science Building, CL 121, Muncie, IN 47306 USA
| | - William M. Twardek
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6 Canada
| | - Robert J. Lennox
- LFI, Freshwater Biology, NORCE Norwegian Research Centre, Nygårdsporten 112, 5006 Bergen, Norway
| | - Jacob W. Brownscombe
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6 Canada
- Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, 867 Lakeshore Rd, Burlington, ON L7S 1A1 Canada
| | - Christian Skov
- Technical University of Denmark, National Institute of Aquatic Resources (DTU Aqua), Vejlsøvej 39, 8600 Silkeborg, Denmark
| | - Kieran Hyder
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Pakefield Road, Lowestoft, Suffolk, NR33 0HT UK
| | - Cory D. Suski
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave, Urbana, IL 61801 USA
| | | | - Robert Arlinghaus
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany
- Division of Integrative Fisheries Management, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
| | - Andy J. Danylchuk
- Department of Environmental Conservation, University of Massachusetts Amherst, 160 Holdsworth Way, Amherst, MA 01003 USA
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Giron-Nava A, Munch SB, Johnson AF, Deyle E, James CC, Saberski E, Pao GM, Aburto-Oropeza O, Sugihara G. Circularity in fisheries data weakens real world prediction. Sci Rep 2020; 10:6977. [PMID: 32332835 PMCID: PMC7181812 DOI: 10.1038/s41598-020-63773-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 12/19/2019] [Indexed: 11/30/2022] Open
Abstract
The systematic substitution of direct observational data with synthesized data derived from models during the stock assessment process has emerged as a low-cost alternative to direct data collection efforts. What is not widely appreciated, however, is how the use of such synthesized data can overestimate predictive skill when forecasting recruitment is part of the assessment process. Using a global database of stock assessments, we show that Standard Fisheries Models (SFMs) can successfully predict synthesized data based on presumed stock-recruitment relationships, however, they are generally less skillful at predicting observational data that are either raw or minimally filtered (denoised without using explicit stock-recruitment models). Additionally, we find that an equation-free approach that does not presume a specific stock-recruitment relationship is better than SFMs at predicting synthesized data, and moreover it can also predict observational recruitment data very well. Thus, while synthesized datasets are cheaper in the short term, they carry costs that can limit their utility in predicting real world recruitment.
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Affiliation(s)
- Alfredo Giron-Nava
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA.,National Center for Ecological Analysis and Synthesis, University of California Santa Barbara, 735 State St #300, Santa Barbara, CA, 93101, USA.,Future Earth, School of Global Environmental Sustainability, Colorado State University, 108 Johnson Dr, Fort Collins, 80523, CO, USA
| | - Stephan B Munch
- Fisheries Ecology Division. Southwest Fisheries Science Center. National Oceanographic and Atmospheric Administration, 110 Shaffer Rd, Santa Cruz, CA, 95060, USA.,Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | | | - Ethan Deyle
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA
| | - Chase C James
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA
| | - Erik Saberski
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA
| | - Gerald M Pao
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA.,Salk Institute of Biological Sciences, 10010 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Octavio Aburto-Oropeza
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA
| | - George Sugihara
- Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr, CA, La Jolla, 92093, USA.
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Winter AM, Richter A, Eikeset AM. Implications of Allee effects for fisheries management in a changing climate: evidence from Atlantic cod. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e01994. [PMID: 31468660 DOI: 10.1002/eap.1994] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 07/13/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
There are concerns that increasing anthropogenic stressors can cause catastrophic transitions in ecosystems. Such shifts have large social, economic, and ecological consequences and therefore have important management implications. A potential mechanism behind these regime shifts is the Allee effect, which describes the decline in realized per capita growth rate at small population density. With an age-structured population model for Atlantic cod, Gadus morhua, we illustrate how interactions between human-induced stressors, such as fishing and climate change, can worsen the impact of an Allee effect on populations by promoting hysteresis. Therefore, the risk of population collapse and recovery failure is exacerbated and the success of preventing and reverting collapse depends on the climate regime. We find that, in presence of the Allee effect, a fishing moratorium is only sufficient for recovery when sea surface temperature rise remains within 2°C and fishing is restricted within 10 yrs. If sea surface temperature rises beyond 2°C, even immediate banning of fishing is not sufficient to guarantee recovery. If fishing is not fully banned and a residual fishing pressure remains, the probability of recovery is further decreased, also in the absence of an Allee effect. The results underscore the decisive role of Allee effects for the management of depleted populations in an increasingly human-dominated world. Once the population collapses and its growth rate is suppressed, rebuilding measures will be squandered and collapse will very likely be irreversible. We therefore emphasize the need for proactive management involving precautionary, adaptive measures and reference points. Our studies shows that climate change has the potential to strengthen Allee effects, which could increasingly challenge fisheries management.
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Affiliation(s)
- Anna-Marie Winter
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, N-0316, Norway
| | - Andries Richter
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, N-0316, Norway
- Environmental Economics and Natural Resources Group, Sub-Department of Economics, Wageningen University, Wageningen, 6700 EW, The Netherlands
| | - Anne Maria Eikeset
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, N-0316, Norway
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Abstract
Salmon were among the first nonmodel species for which systematic population genetic studies of natural populations were conducted, often to support management and conservation. The genomics revolution has improved our understanding of the evolutionary ecology of salmon in two major ways: (a) Large increases in the numbers of genetic markers (from dozens to 104-106) provide greater power for traditional analyses, such as the delineation of population structure, hybridization, and population assignment, and (b) qualitatively new insights that were not possible with traditional genetic methods can be achieved by leveraging detailed information about the structure and function of the genome. Studies of the first type have been more common to date, largely because it has taken time for the necessary tools to be developed to fully understand the complex salmon genome. We expect that the next decade will witness many new studies that take full advantage of salmonid genomic resources.
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Affiliation(s)
- Robin S Waples
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington 98112, USA;
| | - Kerry A Naish
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195-5020, USA;
| | - Craig R Primmer
- Organismal & Evolutionary Biology Research Program and Biotechnology Institute, University of Helsinki, 00014 Helsinki, Finland;
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Bhowmick AR, Sardar T, Bhattacharya S. Estimation of growth regulation in natural populations by extended family of growth curve models with fractional order derivative: Case studies from the global population dynamics database. ECOL INFORM 2019. [DOI: 10.1016/j.ecoinf.2019.100980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Aalto EA, Micheli F, Boch CA, Espinoza Montes JA, Woodson CB, De Leo GA. Catastrophic Mortality, Allee Effects, and Marine Protected Areas. Am Nat 2019; 193:391-408. [DOI: 10.1086/701781] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Bayer SR, Wahle RA, Brady DC, Jumars PA, Stokesbury KDE, Carey JD. Fertilization success in scallop aggregations: reconciling model predictions and field measurements of density effects. Ecosphere 2018. [DOI: 10.1002/ecs2.2359] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- S. R. Bayer
- Darling Marine Center University of Maine Walpole Maine 04573 USA
| | - R. A. Wahle
- Darling Marine Center University of Maine Walpole Maine 04573 USA
| | - D. C. Brady
- Darling Marine Center University of Maine Walpole Maine 04573 USA
| | - P. A. Jumars
- Darling Marine Center University of Maine Walpole Maine 04573 USA
| | - K. D. E. Stokesbury
- Department of Fisheries Oceanography School for Marine Science and Technology University of Massachusetts Dartmouth Fairhaven Massachusetts 02719 USA
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Bateman AW, Ozgul A, Krkošek M, Clutton-Brock TH. Matrix Models of Hierarchical Demography: Linking Group- and Population-Level Dynamics in Cooperative Breeders. Am Nat 2018; 192:188-203. [DOI: 10.1086/698217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Beal A, Rodriguez-Casariego J, Rivera-Casas C, Suarez-Ulloa V, Eirin-Lopez JM. Environmental Epigenomics and Its Applications in Marine Organisms. ACTA ACUST UNITED AC 2018. [DOI: 10.1007/13836_2018_28] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Riegl B, Johnston M, Purkis S, Howells E, Burt J, Steiner SCC, Sheppard CRC, Bauman A. Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem-engineering coral, linked to rising temperature. GLOBAL CHANGE BIOLOGY 2018; 24:2447-2462. [PMID: 29504709 DOI: 10.1111/gcb.14114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 06/08/2023]
Abstract
As in the tropical Atlantic, Acropora populations in the southern Persian/Arabian Gulf plummeted within two decades after having been ecosystem engineers on most wave-exposed reefs since the Pleistocene. Since 1996/1998 live coral cover in the Gulf declined by over 90% in many areas, primarily due to bleaching and diseases caused by rising temperatures. In the formerly dominant table-coral species A. downingi, population dynamics corresponding to disturbance regimes was quantified in three transition matrices (lower disturbance pre-1996; moderate disturbance from 1998 to 2010 and 2013 to 2017, disturbed in 1996/1998, 2010/11/12, 2017). Increased disturbance frequency and severity caused progressive reduction in coral size, cover, and population fecundity. Small size-classes were bolstered more by partial colony mortality than sexual recruitment. Some large corals had a size refuge and resisted die-back but were also lost with increasing disturbance. Matrix and biophysical larval flow models suggested one metapopulation. Southern, Arabian, populations could be connected to northern, Iranian, populations but this connectivity was lost under assumptions of pelagic larval duration at rising temperatures shortened to a third. Then, the metapopulation disintegrated into isolated populations. Connectivity required to avoid extinctions increased exponentially with disturbance frequency and correlation of disturbances across the metapopulation. Populations became unsustainable at eight disturbances in 15 years, when even highest theoretical recruitment no longer compensated mortality. This lethal disturbance frequency was 3-fold that of the moderately disturbed monitoring period and 4-fold of the preceding low-disturbance period-suggesting ongoing shortening of the disturbance-free period. Observed population collapse and environmental changes in the Gulf suggest that A. downingi is heading toward at least functional extinction mainly due to increasingly frequent temperature-induced mortality events, clearly linked to climate change.
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Affiliation(s)
- Bernhard Riegl
- Department of Marine and Environmental Sciences, Halmos College of Natural Sciences and Oceanography, Nova Southeastern University, Dania Beach, FL, USA
| | - Matthew Johnston
- Department of Biology, Halmos College of Natural Sciences and Oceanography, Nova Southeastern University, Dania Beach, FL, USA
| | - Sam Purkis
- Department of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
| | - Emily Howells
- Center for Genomics and Systems Biology, New York University at Abu Dhabi, Abu Dhabi, UAE
| | - John Burt
- Center for Genomics and Systems Biology, New York University at Abu Dhabi, Abu Dhabi, UAE
| | | | | | - Andrew Bauman
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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Rogers LA, Salomon AK, Connors B, Krkošek M. Collapse, Tipping Points, and Spatial Demographic Structure Arising from the Adopted Migrant Life History. Am Nat 2018; 192:49-61. [PMID: 29897803 DOI: 10.1086/697488] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The roles of dispersal and recruitment have long been a focal point in ecology and conservation. The adopted migrant hypothesis proposes a life history in which social learning transmits migratory knowledge between generations of iteroparous fish. Specifically, juveniles disperse from the parental spawning site, encounter and recruit to a local adult population, and learn migration routes between spawning and foraging habitats by following older, experienced fish. Although the adopted migrant life history may apply to many species of pelagic marine fishes, there is scant theoretical or empirical work on the consequent population dynamics. We developed and analyzed a mathematical model of this life history in which the recruitment of juveniles depends on the relative abundance of the local populations and recruitment overlap, which measures the ease with which juveniles are recruited by a nonparental population. We demonstrate that the adopted migrant life history can maintain spatial demographic structure among local populations, that it can also predispose local populations to collapse when a tipping point is crossed, and that recovery after collapse is impaired by reduced recruitment at small local population sizes.
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Perälä T, Kuparinen A. Detection of Allee effects in marine fishes: analytical biases generated by data availability and model selection. Proc Biol Sci 2018; 284:rspb.2017.1284. [PMID: 28855368 DOI: 10.1098/rspb.2017.1284] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 07/21/2017] [Indexed: 11/12/2022] Open
Abstract
The demographic Allee effect, or depensation, implies positive association between per capita population growth rate and population size at low abundances, thereby lowering growth ability of sparse populations. This can have far-reaching consequences on population recovery ability and colonization success. In the context of marine fishes, there is a widespread perception that Allee effects are rare or non-existent. However, studies that have failed to detect Allee effects in marine fishes have suffered from several fundamental methodological and data limitations. In the present study, we challenge the prevailing perception about the rarity of Allee effects by analysing nine populations of Atlantic herring (Clupea harengus), using Bayesian statistical methods. We find that populations of the same species can show either strong evidence for Allee effects or compensation. We explicitly demonstrate how the evidence for Allee effects is strongly provisional on observations made at low population abundances. We contrast our statistical approach with previous attempts to detect Allee effects and illustrate methodological issues that can lead to erroneous conclusions about the nature of population dynamics at low abundance. The present study demonstrates that there is no substantive scientific basis to support the perception that Allee effects are rare or non-existent in marine fishes.
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Affiliation(s)
- Tommi Perälä
- Department of Environmental Sciences, University of Helsinki, PO Box 65, Helsinki 00014, Finland
| | - Anna Kuparinen
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40015, Finland
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Kuparinen A. The mechanistic basis of demographic Allee effects: The search for mates. J Anim Ecol 2017; 87:4-6. [PMID: 29235115 DOI: 10.1111/1365-2656.12774] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 10/09/2017] [Indexed: 11/27/2022]
Abstract
In Focus: Berec, L., Kremer, A.M., Bernhauverova, V., & Drake, J.M. (2017). Density-dependent selection on mate-finding Allee effects. Journal of Animal Ecology, 87, 24-35. https://doi.org/10.1111/1365-2656.12662 In Focus: Shaw, A.K., Kokko, H., & Neubert, M.G. (2017). Details of mate finding drive dynamics of sex structured invasions. Journal of Animal Ecology, 87, 36-46. https://doi.org/10.1111/1365-2656.12658 Lowered population growth ability at low abundances is called the demographic Allee effect. The difficulty of finding mates in a sparse population is the best documented pathway through which a demographic Allee effect might arise. The articles in focus here aim to establish the mechanistic links between mate search component Allee effects and the emergent demographic Allee effect manifested at the level of population growth rate. The authors discover that limitations in the time invested in mate searching generates demographic Allee effects and that the population level adaptations of mate search time are likely to be dependent on the prevailing population density. Trade-offs between mate search, survival and reproductive outputs are key in understanding optimal mate search strategies and their fitness consequences. The present studies provide guidelines to identify populations at risk of experiencing demographic Allee effects at low abundances.
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Affiliation(s)
- Anna Kuparinen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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Affiliation(s)
| | - Luděk Berec
- Department of EcologyInstitute of EntomologyBiology Centre CAS České Budějovice Czech Republic
| | - John M. Drake
- Odum School of EcologyUniversity of Georgia Athens GA USA
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Mintram KS, Brown AR, Maynard SK, Thorbek P, Tyler CR. Capturing ecology in modeling approaches applied to environmental risk assessment of endocrine active chemicals in fish. Crit Rev Toxicol 2017; 48:109-120. [PMID: 28929839 DOI: 10.1080/10408444.2017.1367756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Endocrine active chemicals (EACs) are widespread in freshwater environments and both laboratory and field based studies have shown reproductive effects in fish at environmentally relevant exposures. Environmental risk assessment (ERA) seeks to protect wildlife populations and prospective assessments rely on extrapolation from individual-level effects established for laboratory fish species to populations of wild fish using arbitrary safety factors. Population susceptibility to chemical effects, however, depends on exposure risk, physiological susceptibility, and population resilience, each of which can differ widely between fish species. Population models have significant potential to address these shortfalls and to include individual variability relating to life-history traits, demographic and density-dependent vital rates, and behaviors which arise from inter-organism and organism-environment interactions. Confidence in population models has recently resulted in the EU Commission stating that results derived from reliable models may be considered when assessing the relevance of adverse effects of EACs at the population level. This review critically assesses the potential risks posed by EACs for fish populations, considers the ecological factors influencing these risks and explores the benefits and challenges of applying population modeling (including individual-based modeling) in ERA for EACs in fish. We conclude that population modeling offers a way forward for incorporating greater environmental relevance in assessing the risks of EACs for fishes and for identifying key risk factors through sensitivity analysis. Individual-based models (IBMs) allow for the incorporation of physiological and behavioral endpoints relevant to EAC exposure effects, thus capturing both direct and indirect population-level effects.
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Affiliation(s)
- Kate S Mintram
- a College of Life and Environmental Sciences , University of Exeter , Exeter , UK
| | - A Ross Brown
- a College of Life and Environmental Sciences , University of Exeter , Exeter , UK
| | - Samuel K Maynard
- b Syngenta, Jealott's Hill International Research Centre , Bracknell , Berkshire , UK
| | - Pernille Thorbek
- b Syngenta, Jealott's Hill International Research Centre , Bracknell , Berkshire , UK
| | - Charles R Tyler
- a College of Life and Environmental Sciences , University of Exeter , Exeter , UK
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Adams BK, Cote D, Fleming IA. Stochastic life history modeling for managing regional-scale freshwater fisheries: an experimental study of brook trout. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:899-912. [PMID: 27411259 DOI: 10.1890/14-2379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Environmental heterogeneity can combine with evolutionary responses to create very dynamic and often locally independent populations across a landscape. Such complexity creates difficulties for managers trying to conserve populations across large areas. This study develops, applies, and tests the use of stochastic life history modeling and Monte Carlo simulation to assess management scenarios related to the realities of regional fisheries management and conservation. We apply this approach to the management of recreational brook trout (Salvelinus fontinalis) fishing; an activity that can severely impact species balance, abundance, and the size structure of fish communities. Specifically, the model incorporates population-specific life-history information (e.g., growth rate, reproductive effort, and survival) to allow forecasts of the impact of various management strategies and/or changes to environmental conditions on a population's ecological characteristics (e.g., size structure, abundance, and probability of persistence). Sampling was carried out in 16 water bodies spread across four sites in Atlantic Canada. Each water body was sampled in 2005 and reassessed in 2008. This sampling had two primary objectives: (1) define a significant proportion of life-history variation of brook trout in Atlantic Canada, and (2) to test the precision and accuracy of model predictions of population responses to experimental exploitation and management changes. The model successfully predicted population responses to changes in adult survival in 12 of 13 populations having sufficient data for validation testing, while also proving to be a useful tool when engaging stakeholders regarding management options and their associated risk. We suggest that such models are cost-effective and have great potential for informing proactive management of jurisdictions with numerous and diverse populations.
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de Mitcheson YS. Mainstreaming Fish Spawning Aggregations into Fishery Management Calls for a Precautionary Approach. Bioscience 2016. [DOI: 10.1093/biosci/biw013] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
Studies on small and declining populations dominate research in conservation biology. This emphasis reflects two overarching frameworks: the small-population paradigm focuses on correlates of increased extinction probability; the declining-population paradigm directs attention to the causes and consequences of depletion. Neither, however, particularly informs research on the determinants, rate or uncertainty of population increase. By contrast, Allee effects (positive associations between population size and realized per capita population growth rate, r(realized), a metric of average individual fitness) offer a theoretical and empirical basis for identifying numerical and temporal thresholds at which recovery is unlikely or uncertain. Following a critique of studies on Allee effects, I quantify population-size minima and subsequent trajectories of marine fishes that have and have not recovered following threat mitigation. The data suggest that threat amelioration, albeit necessary, can be insufficient to effect recovery for populations depleted to less than 10% of maximum abundance (N(max)), especially when they remain depleted for lengthy periods of time. Comparing terrestrial and aquatic vertebrates, life-history analyses suggest that population-size thresholds for impaired recovery are likely to be comparatively low for marine fishes but high for marine mammals.Articulation of a 'recovering population paradigm' would seem warranted. It might stimulate concerted efforts to identify generic impaired recovery thresholds across species. It might also serve to reduce the confusion of terminology, and the conflation of causes and consequences with patterns currently evident in the literature on Allee effects, thus strengthening communication among researchers and enhancing the practical utility of recovery-oriented research to conservation practitioners and resource managers.
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Moore DRJ, Breton RL, DeLong TR, Ferson S, Lortie JP, MacDonald DB, McGrath R, Pawlisz A, Svirsky SC, Teed RS, Thompson RP, Whitfield Aslund M. Ecological risk assessment for mink and short-tailed shrew exposed to PCBs, dioxins, and furans in the Housatonic River area. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2016; 12:174-184. [PMID: 25976918 DOI: 10.1002/ieam.1661] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/04/2014] [Accepted: 04/27/2015] [Indexed: 06/04/2023]
Abstract
A probabilistic risk assessment was conducted to characterize risks to a representative piscivorous mammal (mink, Mustela vison) and a representative carnivorous mammal (short-tailed shrew, Blarina brevicauda) exposed to PCBs, dioxins, and furans in the Housatonic River area downstream of the General Electric (GE) facility in Pittsfield, Massachusetts. Contaminant exposure was estimated using a probabilistic total daily intake model and parameterized using life history information of each species and concentrations of PCBs, dioxins, and furans in prey collected in the Housatonic River study area. The effects assessment preferentially relied on dose-response curves but defaulted to benchmarks or other estimates of effect when there were insufficient toxicity data. The risk characterization used a weight of evidence approach. Up to 3 lines of evidence were used to estimate risks to the selected mammal species: 1) probabilistic exposure and effects modeling, 2) field surveys, and 3) species-specific feeding or field studies. The weight of evidence assessment indicated a high risk for mink and an intermediate risk for short-tailed shrew.
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Affiliation(s)
| | - Roger L Breton
- Intrinsik Environmental Sciences, Ottawa, Ontario, Canada
| | - Tod R DeLong
- Avatar Environmental, West Chester, Pennsylvania, USA
| | | | | | - Drew B MacDonald
- Chemicals Evaluation Branch, Environment Canada, Gatineau, Quebec, Canada
| | | | | | - Susan C Svirsky
- US Environmental Protection Agency, New England Office, Boston, Massachusetts
| | - R Scott Teed
- Intrinsik Environmental Sciences, Ottawa, Ontario, Canada
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35
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Bueltmann AT, Phelps QE. Assessment of the Middle Mississippi River Channel Catfish Population. COPEIA 2015. [DOI: 10.1643/ot-14-155] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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36
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Terui A, Miyazaki Y, Yoshioka A, Matsuzaki SIS. A cryptic Allee effect: spatial contexts mask an existing fitness-density relationship. ROYAL SOCIETY OPEN SCIENCE 2015; 2:150034. [PMID: 26543582 PMCID: PMC4632546 DOI: 10.1098/rsos.150034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 05/07/2015] [Indexed: 06/05/2023]
Abstract
Current theories predict that Allee effects should be widespread in nature, but there is little consistency in empirical findings. We hypothesized that this gap can arise from ignoring spatial contexts (i.e. spatial scale and heterogeneity) that potentially mask an existing fitness-density relationship: a 'cryptic' Allee effect. To test this hypothesis, we analysed how spatial contexts interacted with conspecific density to influence the fertilization rate of the freshwater mussel Margaritifera laevis. This sessile organism has a simple fertilization process whereby females filter sperm from the water column; this system enabled us to readily assess the interaction between conspecific density and spatial heterogeneity (e.g. flow conditions) at multiple spatial levels. Our findings were twofold. First, positive density-dependence in fertilization was undetectable at a population scale (approx. less than 50.5 m(2)), probably reflecting the exponential decay of sperm density with distance from the sperm source. Second, the Allee effect was confirmed at a local level (0.25 m(2)), but only when certain flow conditions were met (slow current velocity and shallow water depth). These results suggest that spatial contexts can mask existing Allee effects.
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Affiliation(s)
- Akira Terui
- Department of Forest Science, Graduate School of Agriculture, Hokkaido University, Kita 9, Nishi 9, Kita-ku, Sapporo 060-8589, Japan
| | - Yusuke Miyazaki
- Kanagawa Prefectural Museum of Natural History, 499 Iryuda, Odawara, Kanagawa 250-0031, Japan
| | - Akira Yoshioka
- National Institute for Environmental Studies, Tsukuba-shi, Ibaraki 305-8506, Japan
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Boettiger C, Mangel M, Munch S. Avoiding tipping points in fisheries management through Gaussian process dynamic programming. Proc Biol Sci 2015; 282:20141631. [PMID: 25567644 PMCID: PMC4308990 DOI: 10.1098/rspb.2014.1631] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 12/08/2014] [Indexed: 11/12/2022] Open
Abstract
Model uncertainty and limited data are fundamental challenges to robust management of human intervention in a natural system. These challenges are acutely highlighted by concerns that many ecological systems may contain tipping points, such as Allee population sizes. Before a collapse, we do not know where the tipping points lie, if they exist at all. Hence, we know neither a complete model of the system dynamics nor do we have access to data in some large region of state space where such a tipping point might exist. We illustrate how a Bayesian non-parametric approach using a Gaussian process (GP) prior provides a flexible representation of this inherent uncertainty. We embed GPs in a stochastic dynamic programming framework in order to make robust management predictions with both model uncertainty and limited data. We use simulations to evaluate this approach as compared with the standard approach of using model selection to choose from a set of candidate models. We find that model selection erroneously favours models without tipping points, leading to harvest policies that guarantee extinction. The Gaussian process dynamic programming (GPDP) performs nearly as well as the true model and significantly outperforms standard approaches. We illustrate this using examples of simulated single-species dynamics, where the standard model selection approach should be most effective and find that it still fails to account for uncertainty appropriately and leads to population crashes, while management based on the GPDP does not, as it does not underestimate the uncertainty outside of the observed data.
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Affiliation(s)
- Carl Boettiger
- Center for Stock Assessment Research, Department of Applied Math and Statistics, University of California, Mail Stop SOE-2, Santa Cruz, CA 95064, USA
| | - Marc Mangel
- Center for Stock Assessment Research, Department of Applied Math and Statistics, University of California, Mail Stop SOE-2, Santa Cruz, CA 95064, USA
| | - Stephan Munch
- Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration, 110 Shaffer Road, Santa Cruz, CA 95060, USA
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Hutchings JA. Avoidance of fisheries-induced evolution: management implications for catch selectivity and limit reference points. Evol Appl 2015; 2:324-34. [PMID: 25567884 PMCID: PMC3352487 DOI: 10.1111/j.1752-4571.2009.00085.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Accepted: 05/21/2009] [Indexed: 11/28/2022] Open
Abstract
I examined how the fitness (r) associated with early- and late-maturing genotypes varies with fishing mortality (F) and age-/size-specific probability of capture. Life-history data on Newfoundland's northern Atlantic cod (Gadus morhua) allowed for the estimation of r for individuals maturing at 4 and 7 year in the absence of fishing. Catch selectivity data associated with four types of fishing gear (trap, gillnet, handline, otter trawl) were then incorporated to examine how r varied with gear type and with F. The resulting fitness functions were then used to estimate the F above which selection would favour early (4 year) rather than delayed (7 year) maturity. This evolutionarily-sensitive threshold, F evol, identifies a limit reference point somewhat similar to those used to define overfishing (e.g., F msy, F 0.1). Over-exploitation of northern cod resulted in fishing mortalities considerably greater than those required to effect evolutionary change. Selection for early maturity is reduced by the dome-shaped selectivities characteristic of fixed gears such as handlines (the greater the leptokurtosis, the lower the probability of a selection response) and enhanced by the knife-edged selectivities of bottom trawls. Strategies to minimize genetic change are consistent with traditional management objectives (e.g., yield maximization, population increase). Compliance with harvest control rules guided by evolutionarily-sensitive limit reference points, which may be achieved by adherence to traditional reference points such as F msy and F 0.1, should be sufficient to minimize the probability of fisheries-induced evolution for commercially exploited species.
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Enberg K, Jørgensen C, Dunlop ES, Heino M, Dieckmann U. Implications of fisheries-induced evolution for stock rebuilding and recovery. Evol Appl 2015; 2:394-414. [PMID: 25567888 PMCID: PMC3352485 DOI: 10.1111/j.1752-4571.2009.00077.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2008] [Accepted: 04/27/2009] [Indexed: 01/16/2023] Open
Abstract
Worldwide depletion of fish stocks has led fisheries managers to become increasingly concerned about rebuilding and recovery planning. To succeed, factors affecting recovery dynamics need to be understood, including the role of fisheries-induced evolution. Here we investigate a stock's response to fishing followed by a harvest moratorium by analyzing an individual-based evolutionary model parameterized for Atlantic cod Gadus morhua from its northern range, representative of long-lived, late-maturing species. The model allows evolution of life-history processes including maturation, reproduction, and growth. It also incorporates environmental variability, phenotypic plasticity, and density-dependent feedbacks. Fisheries-induced evolution affects recovery in several ways. The first decades of recovery were dominated by demographic and density-dependent processes. Biomass rebuilding was only lightly influenced by fisheries-induced evolution, whereas other stock characteristics such as maturation age, spawning stock biomass, and recruitment were substantially affected, recovering to new demographic equilibria below their preharvest levels. This is because genetic traits took thousands of years to evolve back to preharvest levels, indicating that natural selection driving recovery of these traits is weaker than fisheries-induced selection was. Our results strengthen the case for proactive management of fisheries-induced evolution, as the restoration of genetic traits altered by fishing is slow and may even be impractical.
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Affiliation(s)
- Katja Enberg
- Department of Biology, University of Bergenyy Bergen, Norway ; Evolution and Ecology Program, International Institute for Applied Systems Analysis Laxenburg, Austria
| | | | - Erin S Dunlop
- Department of Biology, University of Bergenyy Bergen, Norway ; Evolution and Ecology Program, International Institute for Applied Systems Analysis Laxenburg, Austria ; Aquatic Research and Development Section, Ontario Ministry of Natural Resources Peterborough, ON, Canada ; Institute of Marine Research Bergen, Norway
| | - Mikko Heino
- Department of Biology, University of Bergenyy Bergen, Norway ; Evolution and Ecology Program, International Institute for Applied Systems Analysis Laxenburg, Austria ; Institute of Marine Research Bergen, Norway
| | - Ulf Dieckmann
- Evolution and Ecology Program, International Institute for Applied Systems Analysis Laxenburg, Austria
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Schmitt CK, Guill C, Carmack E, Drossel B. Effect of introducing a competitor on cyclic dominance of sockeye salmon. J Theor Biol 2014; 360:13-20. [PMID: 24979740 DOI: 10.1016/j.jtbi.2014.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 05/27/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022]
Abstract
We study the effects of introducing a competing species into a 3-species model for the population dynamics of sockeye salmon, thereby converting a food chain into a diamond module. We find that this often leads to the disappearance of the 4-year oscillation of sockeye salmon known as cyclic dominance when parameters are chosen such that all four species can coexist. Only when the population size of the competitor is small the phenomenon of cyclic dominance can persist. There is also a large region of parameter space where either the sockeye salmon or the competitor goes extinct. We discuss how these findings can be reconciled with the prevalence of cyclic dominance in many sockeye brood lakes.
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Affiliation(s)
- Christoph K Schmitt
- Institut für Festkörperphysik, TU Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany.
| | - Christian Guill
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands.
| | - Eddy Carmack
- Fisheries and Oceans Canada, 9860 West Saanich Road, Sidney B.C., Canada V8L 4B2.
| | - Barbara Drossel
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands.
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Kuparinen A, Stenseth NC, Hutchings JA. Fundamental population-productivity relationships can be modified through density-dependent feedbacks of life-history evolution. Evol Appl 2014; 7:1218-25. [PMID: 25558282 PMCID: PMC4275093 DOI: 10.1111/eva.12217] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 09/02/2014] [Indexed: 01/16/2023] Open
Abstract
The evolution of life histories over contemporary time scales will almost certainly affect population demography. One important pathway for such eco-evolutionary interactions is the density-dependent regulation of population dynamics. Here, we investigate how fisheries-induced evolution (FIE) might alter density-dependent population-productivity relationships. To this end, we simulate the eco-evolutionary dynamics of an Atlantic cod (Gadus morhua) population under fishing, followed by a period of recovery in the absence of fishing. FIE is associated with increases in juvenile production, the ratio of juveniles to mature population biomass, and the ratio of the mature population biomass relative to the total population biomass. In contrast, net reproductive rate (R 0 ) and per capita population growth rate (r) decline concomitantly with evolution. Our findings suggest that FIE can substantially modify the fundamental population-productivity relationships that underlie density-dependent population regulation and that form the primary population-dynamical basis for fisheries stock-assessment projections. From a conservation and fisheries-rebuilding perspective, we find that FIE reduces R 0 and r, the two fundamental correlates of population recovery ability and inversely extinction probability.
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Affiliation(s)
- Anna Kuparinen
- Department of Environmental Sciences, University of Helsinki Helsinki, Finland
| | - Nils Christian Stenseth
- Centre For Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo Oslo, Norway
| | - Jeffrey A Hutchings
- Centre For Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo Oslo, Norway ; Department of Biology, Dalhousie University Halifax, NS, Canada
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42
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Kuparinen A, Hutchings JA. Increased natural mortality at low abundance can generate an Allee effect in a marine fish. ROYAL SOCIETY OPEN SCIENCE 2014; 1:140075. [PMID: 26064531 PMCID: PMC4448890 DOI: 10.1098/rsos.140075] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 09/13/2014] [Indexed: 06/04/2023]
Abstract
Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics into its opposite-a demographic Allee effect. Northwest Atlantic cod (Gadus morhua) stocks collapsed dramatically in the early 1990s and have since shown little sign of recovery. Many experienced dramatic increases in natural mortality, ostensibly attributable in some populations to increased predation by seals. Our findings show that increased natural mortality of a magnitude observed for overfished cod stocks has been more than sufficient to fundamentally alter the dynamics of density-dependent population regulation. The demographic Allee effect generated by these changes can slow down or even impede the recovery of depleted populations even in the absence of fishing.
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Affiliation(s)
- Anna Kuparinen
- Department of Environmental Sciences, University of Helsinki, PO Box 65, 00014, Finland
| | - Jeffrey A. Hutchings
- Department of Biology, Dalhousie University, 1355 Oxford St., PO Box 15000, Halifax, Nova Scotia, B3H 4R2, Canada
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo 0316, Norway
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43
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Quinn TP, Cunningham CJ, Randall J, Hilborn R. Can intense predation by bears exert a depensatory effect on recruitment in a Pacific salmon population? Oecologia 2014; 176:445-56. [DOI: 10.1007/s00442-014-3043-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 08/11/2014] [Indexed: 11/24/2022]
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44
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Modelling the Impact of Marine Reserves on a Population with Depensatory Dynamics. Bull Math Biol 2014; 76:2122-43. [DOI: 10.1007/s11538-014-0003-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 07/25/2014] [Indexed: 11/26/2022]
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45
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Determining the impact of initial age structure on the recovery of a healthy over-harvested population. Ecol Modell 2014. [DOI: 10.1016/j.ecolmodel.2014.04.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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46
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Kuparinen A, Keith DM, Hutchings JA. Allee effect and the uncertainty of population recovery. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2014; 28:790-798. [PMID: 24512300 DOI: 10.1111/cobi.12216] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 09/05/2013] [Indexed: 06/03/2023]
Abstract
Recovery of depleted populations is fundamentally important for conservation biology and sustainable resource harvesting. At low abundance, population growth rate, a primary determinant of population recovery, is generally assumed to be relatively fast because competition is low (i.e., negative density dependence). But population growth can be limited in small populations by an Allee effect. This is particularly relevant for collapsed populations or species that have not recovered despite large reductions in, or elimination of, threats. We investigated how an Allee effect can influence the dynamics of recovery. We used Atlantic cod (Gadus morhua) as the study organism and an empirically quantified Allee effect for the species to parameterize our simulations. We simulated recovery through an individual-based mechanistic simulation model and then compared recovery among scenarios incorporating an Allee effect, negative density dependence, and an intermediate scenario. Although an Allee effect significantly slowed recovery, such that population increase could be negligible even after 100 years or more, it also made the time required for biomass rebuilding much less predictable. Our finding that an Allee effect greatly increased the uncertainty in recovery time frames provides an empirically based explanation for why the removal of threat does not always result in the recovery of depleted populations or species.
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Affiliation(s)
- Anna Kuparinen
- Department of Environmental Sciences, P.O. Box 65, 00014 University of Helsinki, Finland; Ecological Genetics Research Unit, Department of Biosciences, P.O. Box 65, 00014 University of Helsinki, Finland.
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Bousquet N, Chassot E, Duplisea DE, Hammill MO. Forecasting the major influences of predation and environment on cod recovery in the northern Gulf of St. Lawrence. PLoS One 2014; 9:e82836. [PMID: 24523852 PMCID: PMC3921123 DOI: 10.1371/journal.pone.0082836] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 10/29/2013] [Indexed: 11/29/2022] Open
Abstract
The northern Gulf of St. Lawrence (NGSL) stock of Atlantic cod (Gadus morhua), historically the second largest cod population in the Western Atlantic, has known a severe collapse during the early 1990 s and is currently considered as endangered by the Committee on the Status of Endangered Wildlife in Canada. As for many fish populations over the world which are currently being heavily exploited or overfished, urgent management actions in the form of recovery plans are needed for restoring this stock to sustainable levels. Stochastic projections based on a statistical population model incorporating predation were conducted over a period of 30 years (2010–2040) to assess the expected outcomes of alternative fishing strategies on the stock recovery under different scenarios of harp seal (Pagophilus groenlandicus) abundance and environmental conditions. This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock. Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status. Under current or warmer conditions in the Gulf of St. Lawrence, partial recovery might only be achieved by significant reductions in both fishing and predation pressure. In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry.
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Affiliation(s)
- Nicolas Bousquet
- Institut de Mathématiques de Toulouse, UMR 5219 CNRS, Université Paul Sabatier, Toulouse, France
- * E-mail:
| | - Emmanuel Chassot
- Institut de Recherche pour le Développement, UMR 212 EME (IRD/IFREMER/UM2), CRH, France & Seychelles Fishing Authority, Victoria, Seychelles Island
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Levitan DR, Edmunds PJ, Levitan KE. What makes a species common? No evidence of density-dependent recruitment or mortality of the sea urchin Diadema antillarum after the 1983–1984 mass mortality. Oecologia 2014; 175:117-28. [DOI: 10.1007/s00442-013-2871-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 12/19/2013] [Indexed: 01/25/2023]
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50
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Baker MR, Schindler DE, Essington TE, Hilborn R. Accounting for escape mortality in fisheries: implications for stock productivity and optimal management. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2014; 24:55-70. [PMID: 24640534 DOI: 10.1890/12-1871.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Few studies have considered the management implications of mortality to target fish stocks caused by non-retention in commercial harvest gear (escape mortality). We demonstrate the magnitude of this previously unquantified source of mortality and its implications for the population dynamics of exploited stocks, biological metrics, stock productivity, and optimal management. Non-retention in commercial gillnet fisheries for Pacific salmon (Oncorhynchus spp.) is common and often leads to delayed mortality in spawning populations. This represents losses, not only to fishery harvest, but also in future recruitment to exploited stocks. We estimated incidence of non-retention in Alaskan gillnet fisheries for sockeye salmon (O. nerka) and found disentanglement injuries to be extensive and highly variable between years. Injuries related to non-retention were noted in all spawning populations, and incidence of injury ranged from 6% to 44% of escaped salmon across nine river systems over five years. We also demonstrate that non-retention rates strongly correlate with fishing effort. We applied maximum likelihood and Bayesian approaches to stock-recruitment analyses, discounting estimates of spawning salmon to account for fishery-related mortality in escaped fish. Discounting spawning stock estimates as a function of annual fishing effort improved model fits to historical stock-recruitment data in most modeled systems. This suggests the productivity of exploited stocks has been systematically underestimated. It also suggests that indices of fishing effort may be used to predict escape mortality and correct for losses. Our results illustrate how explicitly accounting for collateral effects of fishery extraction may improve estimates of productivity and better inform management metrics derived from estimates of stock-recruitment analyses.
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