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LoScerbo DC, Wilson SM, Robinson KA, Moore JW, Patterson DA. Physiological condition infers habitat choice in juvenile sockeye salmon. CONSERVATION PHYSIOLOGY 2024; 12:coae011. [PMID: 38584988 PMCID: PMC10998697 DOI: 10.1093/conphys/coae011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 01/17/2024] [Accepted: 02/07/2024] [Indexed: 04/09/2024]
Abstract
The amount of time that juvenile salmon remain in an estuary varies among and within populations, with some individuals passing through their estuary in hours while others remain in the estuary for several months. Underlying differences in individual physiological condition, such as body size, stored energy and osmoregulatory function, could drive individual variation in the selection of estuary habitat. Here we investigated the role of variation in physiological condition on the selection of estuarine and ocean habitat by sockeye salmon (Oncorhynchus nerka) smolts intercepted at the initiation of their 650-km downstream migration from Chilko Lake, Fraser River, British Columbia (BC). Behavioural salinity preference experiments were conducted on unfed smolts held in fresh water at three time intervals during their downstream migration period, representing the stage of migration at lake-exit, and the expected timing for estuary-entry and ocean-entry (0, 1 and 3 weeks after lake-exit, respectively). In general, salinity preference behaviour varied across the three time periods consistent with expected transition from river to estuary to ocean. Further, individual physiological condition did influence habitat choice. Smolt condition factor (K) and energy density were positively correlated with salinity preference behaviour in the estuary and ocean outmigration stages, but not at lake-exit. Our results suggest that smolt physiological condition upon reaching the estuary could influence migratory behaviour and habitat selection. This provides evidence on the temporally dependent interplay of physiology, behaviour and migration in wild juvenile Pacific salmon, with juvenile rearing conditions influencing smolt energetic status, which in turn influences habitat choice during downstream migration. The implication for the conservation of migratory species is that the relative importance of stopover habitats may vary as a function of initial condition.
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Affiliation(s)
- Daniella C LoScerbo
- Department of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
- Fisheries and Oceans Canada, Science Branch, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Samantha M Wilson
- Earth2Ocean Research Group, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Kendra A Robinson
- Fisheries and Oceans Canada, Science Branch, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Jonathan W Moore
- Department of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
- Earth2Ocean Research Group, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - David A Patterson
- Fisheries and Oceans Canada, Science Branch, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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2
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Smit T, Clemmesen C, Lemley DA, Adams JB, Bornman E, Strydom NA. Body condition of larval roundherring, Gilchristella aestuaria (family Clupeidae), in relation to harmful algal blooms in a warm-temperate estuary. JOURNAL OF PLANKTON RESEARCH 2023; 45:523-539. [PMID: 37287684 PMCID: PMC10243853 DOI: 10.1093/plankt/fbad013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 03/14/2023] [Indexed: 06/09/2023]
Abstract
Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes that rely on estuaries as nurseries. However, few studies worldwide have quantified these effects despite the global rise in eutrophication. This study presents a novel approach using biochemical body condition analyses to evaluate the impact of HABs on the growth and body condition of the larvae of an estuarine resident fish. Recurrent phytoplankton blooms of Heterosigma akashiwo occur in the warm-temperate Sundays Estuary on the southeast coast of South Africa. The response in body condition and assemblage structure on larval estuarine roundherring (Gilchristella aestuaria) was measured in conjunction with bloom conditions, water quality and zooplanktonic prey and predators. Larvae and early juveniles were sampled during varying intensity levels, duration and frequency of hypereutrophic blooms. This study demonstrated that extensive HABs could significantly impact larval roundherring, G. aestuaria, by decreasing larval nutritional condition and limiting their growth, resulting in poor grow-out into the juvenile phase. Poor condition and growth may likely affect recruitment success to adult populations, and since G. aestuaria is an important forage fish and zooplanktivore, poor recruitment will hold consequences for estuarine food webs.
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Affiliation(s)
- Taryn Smit
- Department of Zoology, Nelson Mandela University, University Way, Po Box 77000, Gqeberha, 6031, South Africa
| | - Catriona Clemmesen
- Helmholtz Centre for Ocean Research (Geomar), Düsternbrooker Weg 20, Kiel 24105, Germany
| | - Daniel A Lemley
- Botany Department, The Institute for Coastal and Marine Research, Nelson Mandela University, University Way, Gqeberha 6031, South Africa
- DSI/NRF South African Research Chair (Sarchi) In Shallow Water Ecosystems, Nelson Mandela University, Gomery Avenue, Gqeberha, 6031, South Africa
| | - Janine B Adams
- Botany Department, The Institute for Coastal and Marine Research, Nelson Mandela University, University Way, Gqeberha 6031, South Africa
- DSI/NRF South African Research Chair (Sarchi) In Shallow Water Ecosystems, Nelson Mandela University, Gomery Avenue, Gqeberha, 6031, South Africa
| | - Eugin Bornman
- Department of Zoology, Nelson Mandela University, University Way, Po Box 77000, Gqeberha, 6031, South Africa
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3
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Aastrup C, Nilsson JÅ, Hasselquist D, Hegemann A. Size and immune function as predictors of predation risk in nestling and newly fledged jackdaws. Anim Behav 2023. [DOI: 10.1016/j.anbehav.2023.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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4
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Strasburg M, Boone MD. Can predators stabilize host–parasite interactions? Changes in aquatic predator identity alter amphibian responses and parasite abundance across life stages. Ecol Evol 2022; 12:e9512. [PMID: 36407903 PMCID: PMC9666717 DOI: 10.1002/ece3.9512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 10/06/2022] [Accepted: 10/23/2022] [Indexed: 11/18/2022] Open
Abstract
The role of parasites can change depending on the food web community. Predators, for instance, can amplify or dilute parasite effects on their hosts. Likewise, exposure to parasites or predators at one life stage can have long‐term consequences on individual performance and survival, which can influence population and disease dynamics. To understand how predators affect amphibian parasite infections across life stages, we manipulated exposure of northern leopard frog (Rana pipiens) tadpoles to three predators (crayfish [Orconectes rusticus], bluegill [Lepomis macrochirus], or mosquitofish [Gambusia affinis]) and to trematode parasites (Echinostoma spp.) in mesocosms and followed juveniles in outdoor terrestrial enclosures through overwintering. Parasites and predators both had strong impacts on metamorphosis with bluegill and parasites individually reducing metamorph survival. However, when fish were present, the negative effects of parasites on survival was not apparent, likely because fish altered community composition via increased algal food resources. Bluegill also reduced snail abundance, which could explain reduced abundance of parasites in surviving metamorphs. Bluegill and parasite exposure increased mass at metamorphosis, which increased metamorph jumping, swimming, and feeding performance, suggesting that larger frogs would experience better terrestrial survival. Effects on size at metamorphosis persisted in the terrestrial environment but did not influence overwintering survival. Based on our results, we constructed stage‐structured population models to evaluate the lethal and sublethal effects of bluegill and parasites on population dynamics. Our models suggested that positive effects of bluegill and parasites on body size may have greater effects on population growth than the direct effects of mortality. This study illustrates how predators can alter the outcome of parasitic infections and highlights the need for long‐term experiments that investigate how changes in host–parasite systems alter population dynamics. We show that some predators reduce parasite effects and have indirect positive effects on surviving individuals potentially increasing host population persistence.
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5
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Impact of squid predation on juvenile fish survival. Sci Rep 2022; 12:11777. [PMID: 35821384 PMCID: PMC9276823 DOI: 10.1038/s41598-022-14389-2] [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: 12/20/2021] [Accepted: 06/06/2022] [Indexed: 11/28/2022] Open
Abstract
Predation is a major source of mortality during the early life stages of marine fishes; however, few studies have demonstrated its impact—especially that of squid predation—on survival processes. Here, we examined the feeding habits and predation impacts of swordtip squid on a major prey fish, juveniles of jack mackerel, in the East China Sea. Otoliths of the juveniles extracted from the squid stomach were used to reconstruct the age–length relationship and the growth trajectory of the consumed juveniles, and they were compared to those of juveniles collected with a net using a newly developed statistical framework. The juveniles consumed by squid had significantly shorter body lengths and smaller body sizes during the late larval and early juvenile stages than the netted juveniles, suggesting that smaller juveniles with slower growth rates have a higher probability to be selected. The body mass ratio of the predator squid to prey juveniles (predator–prey mass ratio, PPMR) ranged from 7 to 700, which was remarkably lower than the PPMR reported in various marine ecosystems based on analyses of fishes. Our findings demonstrate that squid predation can significantly impact the early life survival of fish and the trophodynamics in marine ecosystems.
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Bass AL, Bateman AW, Connors BM, Staton BA, Rondeau EB, Mordecai GJ, Teffer AK, Kaukinen KH, Li S, Tabata AM, Patterson DA, Hinch SG, Miller KM. Identification of infectious agents in early marine Chinook and Coho salmon associated with cohort survival. Facets (Ott) 2022. [DOI: 10.1139/facets-2021-0102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Recent decades have seen an increased appreciation for the role infectious diseases can play in mass mortality events across a diversity of marine taxa. At the same time many Pacific salmon populations have declined in abundance as a result of reduced marine survival. However, few studies have explicitly considered the potential role pathogens could play in these declines. Using a multi-year dataset spanning 59 pathogen taxa in Chinook and Coho salmon sampled along the British Columbia coast, we carried out an exploratory analysis to quantify evidence for associations between pathogen prevalence and cohort survival and between pathogen load and body condition. While a variety of pathogens had moderate to strong negative correlations with body condition or survival for one host species in one season, we found that Tenacibaculum maritimum and Piscine orthoreovirus had consistently negative associations with body condition in both host species and seasons and were negatively associated with survival for Chinook salmon collected in the fall and winter. Our analyses, which offer the most comprehensive examination of associations between pathogen prevalence and Pacific salmon survival to date, suggest that pathogens in Pacific salmon warrant further attention, especially those whose distribution and abundance may be influenced by anthropogenic stressors.
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Affiliation(s)
- Arthur L. Bass
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Andrew W. Bateman
- Pacific Salmon Foundation, Vancouver, BC V6J 4S6, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Brendan M. Connors
- Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC V8L 5T5, Canada
| | - Benjamin A. Staton
- Fisheries Science Department, Columbia River Inter-Tribal Fish Commission, Portland, OR 97232, USA
| | - Eric B. Rondeau
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
| | - Gideon J. Mordecai
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC V9T 6N7, Canada
| | - Amy K. Teffer
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Karia H. Kaukinen
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
| | - Shaorong Li
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
| | - Amy M. Tabata
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
| | - David A. Patterson
- Fisheries and Oceans Canada, School of Resource and Environmental Management, Simon Fraser University, Science Branch, Burnaby, BC V5A 1S6, Canada
| | - Scott G. Hinch
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Kristina M. Miller
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
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Gosselin JL, Buhle ER, Van Holmes C, Beer WN, Iltis S, Anderson JJ. Role of carryover effects in conservation of wild Pacific salmon migrating regulated rivers. Ecosphere 2021. [DOI: 10.1002/ecs2.3618] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Jennifer L. Gosselin
- School of Aquatic and Fishery Sciences University of Washington 1122 NE Boat Street Seattle Washington 98105 USA
| | - Eric R. Buhle
- Biomark Applied Biological Services Boise Idaho 83702 USA
| | - Christopher Van Holmes
- School of Aquatic and Fishery Sciences University of Washington 1122 NE Boat Street Seattle Washington 98105 USA
| | - W. Nicholas Beer
- School of Aquatic and Fishery Sciences University of Washington 1122 NE Boat Street Seattle Washington 98105 USA
| | - Susannah Iltis
- School of Aquatic and Fishery Sciences University of Washington 1122 NE Boat Street Seattle Washington 98105 USA
| | - James J. Anderson
- School of Aquatic and Fishery Sciences University of Washington 1122 NE Boat Street Seattle Washington 98105 USA
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8
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Sabal MC, Boyce MS, Charpentier CL, Furey NB, Luhring TM, Martin HW, Melnychuk MC, Srygley RB, Wagner CM, Wirsing AJ, Ydenberg RC, Palkovacs EP. Predation landscapes influence migratory prey ecology and evolution. Trends Ecol Evol 2021; 36:737-749. [PMID: 33994219 DOI: 10.1016/j.tree.2021.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 12/23/2022]
Abstract
Migratory prey experience spatially variable predation across their life cycle. They face unique challenges in navigating this predation landscape, which affects their perception of risk, antipredator responses, and resulting mortality. Variable and unfamiliar predator cues during migration can limit accurate perception of risk and migrants often rely on social information and learning to compensate. The energetic demands of migration constrain antipredator responses, often through context-dependent patterns. While migration can increase mortality, migrants employ diverse strategies to balance risks and rewards, including life history and antipredator responses. Humans interact frequently with migratory prey across space and alter both mortality risk and antipredator responses, which can scale up to affect migratory populations and should be considered in conservation and management.
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Affiliation(s)
- Megan C Sabal
- University of California Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA.
| | - Mark S Boyce
- University of Alberta, Department of Biological Sciences, Edmonton T6G 2E9, Canada
| | | | - Nathan B Furey
- University of New Hampshire, Department of Biological Sciences, Durham, NH 03824, USA
| | - Thomas M Luhring
- Wichita State University, Department of Biological Sciences, Wichita, KS 67260, USA
| | - Hans W Martin
- University of Montana, Wildlife Biology Program, W.A. Franke College of Forestry and Conservation, Missoula, MT 59812, USA
| | - Michael C Melnychuk
- University of Washington, School of Aquatic and Fishery Sciences, Seattle, WA 98195, USA
| | - Robert B Srygley
- Pest Management Research Unit, Northern Plains Agricultural Research Laboratory, USDA-Agricultural Research Service, Sidney, MT 59270, USA; Smithsonian Tropical Research Institute, Apdo. 0843-03092, Panamá, República de Panamá
| | - C Michael Wagner
- Michigan State University, Department of Fisheries and Wildlife, East Lansing, MI 48824, USA
| | - Aaron J Wirsing
- University of Washington, School of Environmental and Forest Sciences, Seattle, WA 98195, USA
| | - Ronald C Ydenberg
- Simon Fraser University, Centre for Wildlife Ecology, Burnaby, British Columbia V5A 1S6, Canada
| | - Eric P Palkovacs
- University of California Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
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9
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Sherker Z, Pellett K, Atkinson J, Damborg J, Trites A. Pacific Great Blue Herons ( Ardea herodias fannini) consume thousands of juvenile salmon ( Oncorhynchus spp.). CAN J ZOOL 2021. [DOI: 10.1139/cjz-2020-0189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An array of predators that consume juvenile salmon (genus Oncorhynchus Suckley, 1861) may account for the poor returns of adult salmon to the Salish Sea. However, the Pacific Great Blue Heron (Ardea herodias fannini Chapman, 1901) is rarely listed among the known salmon predators, despite being regularly seen near salmon streams. Investigating heron predation by scanning nesting sites within 35 km of three British Columbia (Canada) rivers for fecal remains containing passive integrated transponder (PIT) tags implanted in >100 000 juvenile salmon from 2008 to 2018 yielded 1205 tags, representing a minimum annual predation rate of 0.3%–1.3% of all juvenile salmon. Most of this predation (99%) was caused by ∼420 adult Pacific Great Blue Herons from three heronries. Correcting for tags defecated outside of the heronry raised the predation rates to 0.7%–3.2%, and was as high as 6% during a year of low river flow. Predation occurs during chick-rearing in late spring and accounts for 4.1%–8.4% of the Pacific Great Blue Heron chick diet. Smaller salmon smolts were significantly more susceptible to Pacific Great Blue Heron predation than larger conspecifics. The proximity of heronries relative to salmon-bearing rivers is likely a good predictor of Pacific Great Blue Heron predation on local salmon runs, and can be monitored to assess coast-wide effects of Pacific Great Blue Herons on salmon recovery.
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Affiliation(s)
- Z.T. Sherker
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, The University of British Columbia, AERL, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - K. Pellett
- South Coast Stock Assessment Division, Fisheries and Oceans Canada, 3225 Stephenson Point Road, Nanaimo, BC V9T 1K3, Canada
| | - J. Atkinson
- Vancouver Island Division, British Columbia Conservation Foundation, 105-1885 Boxwood Road, Nanaimo, BC V9S 5X9, Canada
| | - J. Damborg
- Vancouver Island Division, British Columbia Conservation Foundation, 105-1885 Boxwood Road, Nanaimo, BC V9S 5X9, Canada
| | - A.W. Trites
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, The University of British Columbia, AERL, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
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10
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Wilson SM, Robinson KA, Gutzmann S, Moore JW, Patterson DA. Limits on performance and survival of juvenile sockeye salmon ( Oncorhynchus nerka) during food deprivation: a laboratory-based study. CONSERVATION PHYSIOLOGY 2021; 9:coab014. [PMID: 33815801 PMCID: PMC8009553 DOI: 10.1093/conphys/coab014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 02/23/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
Long-distance migrations can be energetically demanding and can represent phases of high mortality. Understanding relationships between body condition and migratory performance can help illuminate the challenges and vulnerabilities of migratory species. Juvenile anadromous sockeye salmon (Oncorhynchus nerka) may migrate over 1000 km from their freshwater nursery habitats to estuary and ocean feeding grounds. During the period corresponding to the seaward migration of sockeye salmon, we held smolts in the laboratory to ask the following: (i) Does non-feeding migration duration influence prolonged swim performance and survival? (ii) What are the relationships between individual body condition and swim performance and survival? Wild sockeye salmon were intercepted during their migration and held without food for up to 61 days to represent the non-feeding freshwater migration and the extremes of poor estuary habitat. We conducted 40 sets of prolonged swim trials on 319 fish from 3 treatment groups that represented entrance to the marine environment on (i) an average,(ii) a delayed and (iii) a severely delayed migration schedule. Experimentally controlled freshwater migration duration did not impact swim performance or survival. Swim performance decreased concomitant with condition factor, where smolts with a Fulton's condition factor of <0.69 were less likely (<50% probability) to complete the swim test (90 min swim test, at ~0.50 m/s). Survival of salmon smolts in the laboratory was less likely at energy densities of less than 3.47 MJ/kg. Swim performance decreased much sooner than survival, suggesting that swim performance, and therefore condition factor, may be a good indicator of survival of migratory smolts, as fish with reduced swim performance will likely be predated. These two relationships, one more ecologically relevant and one more clinical, help reveal the limits of long-distance migration for juvenile salmon and can be used to determine population-specific starvation risk associated with various freshwater and marine habitat conditions.
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Affiliation(s)
- Samantha M Wilson
- Earth to Ocean Research Group, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Kendra A Robinson
- Fisheries and Oceans Canada, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Sarah Gutzmann
- Earth to Ocean Research Group, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Jonathan W Moore
- Earth to Ocean Research Group, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - David A Patterson
- Fisheries and Oceans Canada, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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11
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Furey NB, Bass AL, Miller KM, Li S, Lotto AG, Healy SJ, Drenner SM, Hinch SG. Infected juvenile salmon can experience increased predation during freshwater migration. ROYAL SOCIETY OPEN SCIENCE 2021; 8:201522. [PMID: 33959321 PMCID: PMC8074935 DOI: 10.1098/rsos.201522] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 03/03/2021] [Indexed: 05/07/2023]
Abstract
Predation risk for animal migrants can be impacted by physical condition. Although size- or condition-based selection is often observed, observing infection-based predation is rare due to the difficulties in assessing infectious agents in predated samples. We examined predation of outmigrating sockeye salmon (Oncorhynchus nerka) smolts by bull trout (Salvelinus confluentus) in south-central British Columbia, Canada. We used a high-throughput quantitative polymerase chain reaction (qPCR) platform to screen for the presence of 17 infectious agents found in salmon and assess 14 host genes associated with viral responses. In one (2014) of the two years assessed (2014 and 2015), the presence of infectious haematopoietic necrosis virus (IHNv) resulted in 15-26 times greater chance of predation; in 2015 IHNv was absent among all samples, predated or not. Thus, we provide further evidence that infection can impact predation risk in migrants. Some smolts with high IHNv loads also exhibited gene expression profiles consistent with a virus-induced disease state. Nine other infectious agents were observed between the two years, none of which were associated with increased selection by bull trout. In 2014, richness of infectious agents was also associated with greater predation risk. This is a rare demonstration of predator consumption resulting in selection for prey that carry infectious agents. The mechanism by which this selection occurs is not yet determined. By culling infectious agents from migrant populations, fish predators could provide an ecological benefit to prey.
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Affiliation(s)
- Nathan B. Furey
- Department of Biological Sciences, University of New Hampshire, Durham, NH, USA
| | - Arthur L. Bass
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, Canada
| | - Kristi M. Miller
- Fisheries and Oceans Canada, Molecular Genetics Section, Pacific Biological Station, Nanaimo, Canada
| | - Shaorong Li
- Fisheries and Oceans Canada, Molecular Genetics Section, Pacific Biological Station, Nanaimo, Canada
| | - Andrew G. Lotto
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, Canada
| | - Stephen J. Healy
- Fisheries and Oceans Canada, Science Branch, Pacific Region, 4160 Marine Dr., West Vancouver, British Columbia, Canada
| | - S. Matthew Drenner
- Stillwater Sciences, 555 W. Fifth St, 35th floor, Los Angeles, CA, USA
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Scott G. Hinch
- Pacific Salmon Ecology and Conservation Laboratory, Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, Canada
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12
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Harding HR, Gordon TAC, Wong K, McCormick MI, Simpson SD, Radford AN. Condition-dependent responses of fish to motorboats. Biol Lett 2020; 16:20200401. [PMID: 33202186 PMCID: PMC7728680 DOI: 10.1098/rsbl.2020.0401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 10/21/2020] [Indexed: 12/17/2022] Open
Abstract
Anthropogenic noise is a pollutant of global concern that has been shown to have a wide range of detrimental effects on multiple taxa. However, most noise studies to-date consider only overall population means, ignoring the potential for intraspecific variation in responses. Here, we used field experiments on Australia's Great Barrier Reef to assess condition-dependent responses of blue-green damselfish (Chromis viridis) to real motorboats. Despite finding no effect of motorboats on a physiological measure (opercular beat rate; OBR), we found a condition-dependent effect on anti-predator behaviour. In ambient conditions, startle responses to a looming stimulus were equivalent for relatively poor- and good-condition fish, but when motorboats were passing, poorer-condition fish startled at significantly shorter distances to the looming stimulus than better-condition fish. This greater susceptibility to motorboats in poorer-condition fish may be the result of generally more elevated stress levels, as poorer-condition fish had a higher pre-testing OBR than those in better condition. Considering intraspecific variation in responses is important to avoid misrepresenting potential effects of anthropogenic noise and to ensure the best management and mitigation of this pervasive pollutant.
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Affiliation(s)
- H. R. Harding
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
- Marine Scotland Science, 375 Victoria Road, Aberdeen AB11 9DB, UK
| | - T. A. C. Gordon
- Biosciences, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter EX4 4PS, UK
- Australian Institute of Marine Science, Perth WA 6009, Australia
| | - K. Wong
- Department of Biology, Duke University, Durham NC 27708, USA
| | - M. I. McCormick
- ARC Centre for Coral Reef Studies, James Cook University, Queensland 4811, Australia
| | - S. D. Simpson
- Biosciences, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter EX4 4PS, UK
| | - A. N. Radford
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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13
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Ulaski ME, Finkle H, Westley PAH. Direction and magnitude of natural selection on body size differ among age-classes of seaward-migrating Pacific salmon. Evol Appl 2020; 13:2000-2013. [PMID: 32908600 PMCID: PMC7463379 DOI: 10.1111/eva.12957] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 01/29/2020] [Accepted: 02/24/2020] [Indexed: 11/29/2022] Open
Abstract
Due to the mediating role of body size in determining fitness, the "bigger-is-better" hypothesis still pervades evolutionary ecology despite evidence that natural selection on phenotypic traits varies in time and space. For Pacific salmon (genus Oncorhynchus), most individual studies quantify selection across a narrow range of sizes and ages; therefore, uncertainties remain concerning how selection on size may differ among diverse life histories. Here, we quantify the direction and magnitude of natural selection on body size among age-classes of multiple marine cohorts of O. nerka (sockeye salmon). Across four cohorts of seaward migrants, we calculated standardized selection differentials by comparing observed size distributions of out-migrating juvenile salmon to back-calculated smolt length from the scales of surviving, returning adults. Results reveal the magnitude of selection on size was very strong (>90th percentile compared to a database of 3,759 linear selection differentials) and consistent among years. However, the direction of selection on size consistently varied among age-classes. Selection was positive for fish migrating to sea after two years in freshwater (age 2) and in their first year of life (age 0), but negative for fish migrating after 1 year in freshwater (age 1). The absolute magnitude of selection was negatively correlated to mean ocean-entry timing, which may underpin negative selection favoring small age-1 fish, given associations between size and timing of seaward migration. Collectively, these results indicate that "bigger is not always better" in terms of survival and emphasize trade-offs that may exist between fitness components for organisms with similarly diverse migratory life histories.
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Affiliation(s)
- Marta E. Ulaski
- Department of FisheriesCollege of Fisheries and Ocean SciencesUniversity of Alaska FairbanksFairbanksAlaska
| | | | - Peter A. H. Westley
- Department of FisheriesCollege of Fisheries and Ocean SciencesUniversity of Alaska FairbanksFairbanksAlaska
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14
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Haeseker SL, Scheer G, McCann J. Avian Predation on Steelhead is Consistent with Compensatory Mortality. J Wildl Manage 2020. [DOI: 10.1002/jwmg.21880] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Steven L. Haeseker
- U.S. Fish and Wildlife Service, Columbia River Fish and Wildlife Conservation Office 1211 SE Cardinal Ct, Suite 100 Vancouver WA 98683 USA
| | - Gabriel Scheer
- Fish Passage Center 847 NE 19th Ave, Suite 250 Portland OR 97232 USA
| | - Jerry McCann
- Fish Passage Center 847 NE 19th Ave, Suite 250 Portland OR 97232 USA
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15
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Polivka CM. Habitat affinity and density‐dependent movement as indicators of fish habitat restoration efficacy. Ecosphere 2020. [DOI: 10.1002/ecs2.3166] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Carlos M. Polivka
- Pacific Northwest Research Station USDA Forest Service Wenatchee Washington98801USA
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16
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Warriner TR, Semeniuk CAD, Pitcher TE, Love OP. Exposure to exogenous egg cortisol does not rescue juvenile Chinook salmon body size, condition, or survival from the effects of elevated water temperatures. Ecol Evol 2020; 10:2466-2477. [PMID: 32184994 PMCID: PMC7069292 DOI: 10.1002/ece3.6073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 01/03/2020] [Accepted: 01/09/2020] [Indexed: 12/13/2022] Open
Abstract
Climate change is leading to altered temperature regimes which are impacting aquatic life, particularly for ectothermic fish. The impacts of environmental stress can be translated across generations through maternally derived glucocorticoids, leading to altered offspring phenotypes. Although these maternal stress effects are often considered negative, recent studies suggest this maternal stress signal may prepare offspring for a similarly stressful environment (environmental match). We applied the environmental match hypothesis to examine whether a prenatal stress signal can dampen the effects of elevated water temperatures on body size, condition, and survival during early development in Chinook salmon Oncorhynchus tshawytscha from Lake Ontario, Canada. We exposed fertilized eggs to prenatal exogenous egg cortisol (1,000 ng/ml cortisol or 0 ng/ml control) and then reared these dosed groups at temperatures indicative of current (+0°C) and future (+3°C) temperature conditions. Offspring reared in elevated temperatures were smaller and had a lower survival at the hatchling developmental stage. Overall, we found that our exogenous cortisol dose did not dampen effects of elevated rearing temperatures (environmental match) on body size or early survival. Instead, our eyed stage survival indicates that our prenatal cortisol dose may be detrimental, as cortisol-dosed offspring raised in elevated temperatures had lower survival than cortisol-dosed and control reared in current temperatures. Our results suggest that a maternal stress signal may not be able to ameliorate the effects of thermal stress during early development. However, we highlight the importance of interpreting the fitness impacts of maternal stress within an environmentally relevant context.
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Affiliation(s)
- Theresa R. Warriner
- Great Lakes Institute for Environmental ResearchUniversity of WindsorWindsorOntarioCanada
| | - Christina A. D. Semeniuk
- Great Lakes Institute for Environmental ResearchUniversity of WindsorWindsorOntarioCanada
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
| | - Trevor E. Pitcher
- Great Lakes Institute for Environmental ResearchUniversity of WindsorWindsorOntarioCanada
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
| | - Oliver P. Love
- Great Lakes Institute for Environmental ResearchUniversity of WindsorWindsorOntarioCanada
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
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17
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Teffer AK, Hinch S, Miller K, Jeffries K, Patterson D, Cooke S, Farrell A, Kaukinen KH, Li S, Juanes F. Cumulative Effects of Thermal and Fisheries Stressors Reveal Sex-Specific Effects on Infection Development and Early Mortality of Adult Coho Salmon ( Oncorhynchus kisutch). Physiol Biochem Zool 2020; 92:505-529. [PMID: 31397628 DOI: 10.1086/705125] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Multiple stressors are commonly encountered by wild animals, but their cumulative effects are poorly understood, especially regarding infection development. We conducted a holding study with repeated gill and blood sampling to characterize the effects of cumulative stressors on infection development in adult coho salmon. Treatments included chronic thermal stress (15°C vs. 10°C) and acute gill net entanglement with an air exposure (simulating fisheries bycatch release). The potential loadings of 35 infectious agents and the expression of 17 host immune genes were quantified using high-throughput quantitative polymerase chain reaction, while host physiology was characterized with chemical analysis of blood. Temporal increases in infectious agent richness and loads were concurrent with decreased expression of immune genes in fish sampled in the river. In the laboratory, mortality was minimal in cool water regardless of fishery treatment (<15%). Elevated water temperature under laboratory conditions increased mortality of males and females (8% and 28% mortality, respectively, delayed by >1 wk) and enhanced mortality associated with handling and biopsy (∼40% both sexes). Experimental gillnetting at high temperature further enhanced female mortality (73%). Fish held at high temperature demonstrated heavier infectious agent loads, osmoregulatory impairment, suppressed female maturation, and upregulation of inflammatory and extracellular immune genes. At high temperature, heavy Parvicapsula minibicornis loads were associated with premature mortality. Females exhibited physiological impairment from both stressors after 1 wk, and infection burdens correlated poorly with immune gene regulation compared with males. Cumulative effects of multiple stressors on female mortality are likely a function of physiological impairment and enhanced infections at high temperature.
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18
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Nelson BW, Shelton AO, Anderson JH, Ford MJ, Ward EJ. Ecological implications of changing hatchery practices for Chinook salmon in the Salish Sea. Ecosphere 2019. [DOI: 10.1002/ecs2.2922] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Affiliation(s)
- Benjamin W. Nelson
- Contractor to the Northwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration 2725 Montlake Boulevard East Seattle Washington 98112 USA
- Institute for the Oceans and Fisheries University of British Columbia 2202 Main Mall Vancouver British Columbia V6T 1Z4 Canada
| | - Andrew O. Shelton
- Northwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration 2725 Montlake Boulevard East Seattle Washington 98112 USA
| | - Joseph H. Anderson
- Washington Department of Fish and Wildlife P.O. Box 43200 Olympia Washington 98504‐3200 USA
| | - Michael J. Ford
- Northwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration 2725 Montlake Boulevard East Seattle Washington 98112 USA
| | - Eric J. Ward
- Northwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration 2725 Montlake Boulevard East Seattle Washington 98112 USA
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19
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Hipfner JM, Galbraith M, Tucker S, Studholme KR, Domalik AD, Pearson SF, Good TP, Ross PS, Hodum P. Two forage fishes as potential conduits for the vertical transfer of microfibres in Northeastern Pacific Ocean food webs. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 239:215-222. [PMID: 29655068 DOI: 10.1016/j.envpol.2018.04.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 04/01/2018] [Accepted: 04/02/2018] [Indexed: 05/20/2023]
Abstract
We assessed the potential role played by two vital Northeastern Pacific Ocean forage fishes, the Pacific sand lance (Ammodytes personatus) and Pacific herring (Clupea pallasii), as conduits for the vertical transfer of microfibres in food webs. We quantified the number of microfibres found in the stomachs of 734 sand lance and 205 herring that had been captured by an abundant seabird, the rhinoceros auklet (Cerorhinca monocerata). Sampling took place on six widely-dispersed breeding colonies in British Columbia, Canada, and Washington State, USA, over one to eight years. The North Pacific Ocean is a global hotspot for pollution, yet few sand lance (1.5%) or herring (2.0%) had ingested microfibres. In addition, there was no systematic relationship between the prevalence of microplastics in the fish stomachs vs. in waters around three of our study colonies (measured in an earlier study). Sampling at a single site (Protection Island, WA) in a single year (2016) yielded most (sand lance) or all (herring) of the microfibres recovered over the 30 colony-years of sampling involved in this study, yet no microfibres had been recovered there, in either species, in the previous year. We thus found no evidence that sand lance and herring currently act as major food-web conduits for microfibres along British Columbia's outer coast, nor that the local at-sea density of plastic necessarily determines how much plastic enters marine food webs via zooplanktivores. Extensive urban development around the Salish Sea probably explains the elevated microfibre loads in fishes collected on Protection Island, but we cannot account for the between-year variation. Nonetheless, the existence of such marked interannual variation indicates the importance of measuring year-to-year variation in microfibre pollution both at sea and in marine biota.
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Affiliation(s)
- J Mark Hipfner
- Wildlife Research Division, Environment and Climate Change Canada, RR#1 5421 Robertson Road, Delta, BC, V4K 3N2, Canada.
| | - Moira Galbraith
- Institute of Ocean Sciences, Fisheries and Oceans Canada 9860 West Saanich Road, Sidney, BC, V8L 4B2, Canada
| | - Strahan Tucker
- Pacific Biological Station, Fisheries and Oceans Canada 3190 Hammond Bay Road, Nanaimo, BC, V9T 6N7, Canada
| | - Katharine R Studholme
- Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS, B3H 4R2, Canada
| | - Alice D Domalik
- Centre for Wildlife Ecology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Scott F Pearson
- Washington Department of Fish and Wildlife, 1111 Washington Street SE, Olympia, WA, 98501, USA
| | - Thomas P Good
- Northwest Fisheries Science Center, National Marine Fisheries Service 2725 Montlake Boulevard East, Seattle, WA, 98112, USA
| | - Peter S Ross
- Coastal Ocean Research Institute, Ocean Wise Conservation Association, P.O. Box 3232, Vancouver, BC, V6B 3X8, Canada
| | - Peter Hodum
- Department of Biology, University of Puget Sound Tacoma, WA, 98416, USA
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20
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Beacham TD, Araujo HA, Tucker S, Trudel M. Validity of inferring size-selective mortality and a critical size limit in Pacific salmon from scale circulus spacing. PLoS One 2018; 13:e0199418. [PMID: 29944683 PMCID: PMC6019399 DOI: 10.1371/journal.pone.0199418] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 06/07/2018] [Indexed: 11/23/2022] Open
Abstract
Size-selective mortality owing to lack of energy reserves during the first marine winter has been suggested to be a result of juvenile salmon failing to reach a critical size or condition by the end of their first marine summer and not surviving the following winter due to this presumed energy deficit. This hypothesis implies strong size dependency of mortality, and is subject to empirical data support for acceptance. Scale circulus spacing has been interpreted as an index for body size, and we reviewed the effect of size-selective mortality with a knife-edge mortality function on descriptive statistics for a scale circulus spacing index (SCSI). In order to invoke size selection as an important driver of mortality during the first year of ocean rearing, it is necessary to demonstrate not only that size-selective mortality is directed towards the smaller members of the population, but that the selective nature of the mortality can account for a substantial portion of the observed mortality. If the assumption is made that a random sample of a single juvenile population has been obtained, then studies that employ a SCSI to infer size-selective mortality coupled with a critical size limit must demonstrate a shift toward larger values of the SCSI, but also a concomitant reduction in the variance and range of the SCSI and an increase in the skewness and kurtosis of the SCSI values. Through simulation we found that the percentage of adults that displayed a SCSI value greater than the maximum observed in the juvenile sample was highly dependent on the initial juvenile sample size and size-selective mortality rate. Geographical distributions of juvenile Pacific salmon can be stratified by size, with larger individuals migrating earlier from local ocean entry locations than smaller individuals, and thus differential timing migration of juveniles based upon body size prior to the collection of the marine juvenile sample may be a more plausible explanation of published trends in the SCSI, rather than invoking substantial size-selective mortality and a critical size limit.
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Affiliation(s)
- Terry D. Beacham
- Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, B. C, Canada
- * E-mail:
| | - H. Andres Araujo
- Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, B. C, Canada
| | - Strahan Tucker
- Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, B. C, Canada
| | - Marc Trudel
- Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, B. C, Canada
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21
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Griffiths JI, Petchey OL, Pennekamp F, Childs DZ. Linking intraspecific trait variation to community abundance dynamics improves ecological predictability by revealing a growth–defence trade‐off. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12997] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jason I. Griffiths
- Department of Animal and Plant SciencesUniversity of Sheffield Sheffield UK
| | - Owen L. Petchey
- Department of Evolutionary Biology and Environmental StudiesUniversity of Zurich Zurich Switzerland
| | - Frank Pennekamp
- Department of Evolutionary Biology and Environmental StudiesUniversity of Zurich Zurich Switzerland
| | - Dylan Z. Childs
- Department of Animal and Plant SciencesUniversity of Sheffield Sheffield UK
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22
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Mahony AM, Johnson SC, Neville CM, Thiess ME, Jones SRM. Myxobolus arcticus and Parvicapsula minibicornis infections in sockeye salmon Oncorhynchus nerka following downstream migration in British Columbia. DISEASES OF AQUATIC ORGANISMS 2017; 126:89-98. [PMID: 29044039 DOI: 10.3354/dao03158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Factors influencing the health of sockeye salmon Oncorhynchus nerka in British Columbia, Canada, are important for fisheries management and conservation. Juvenile salmon originating from the Fraser River were screened for 3 enzootic parasites (Myxobolus arcticus, Parvicapsula minibicornis, Ceratonova shasta) and the bacterium Renibacterium salmoninarum. Fish were collected from the Strait of Georgia in 2010, 2011 and 2012 and genotyped to stock of origin. Trends in infection status were estimated by year, spawning zone and catch area. The annual prevalences of P. minibicornis (n = 1448) were 23.3, 6.5 and 8.1%, and for M. arcticus (n = 1343), annual prevalences were 40.4, 66.3 and 27.4%, respectively. Logistic regression showed that P. minibicornis was most strongly associated with salmon from the lower Fraser River spawning zone and increased with distance caught from the mouth of the Fraser River. In contrast, infection with M. arcticus was most strongly associated with salmon from the middle Fraser River spawning zone, and there was no trend related to distance from the Fraser River. Neither R. salmoninarum nor C. shasta were detected. These observations are discussed in the context of salmon life history and pathogen biology.
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Affiliation(s)
- A M Mahony
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia V9T 6N7, Canada
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23
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Furey NB, Hinch SG, Bass AL, Middleton CT, Minke-Martin V, Lotto AG. Predator swamping reduces predation risk during nocturnal migration of juvenile salmon in a high-mortality landscape. J Anim Ecol 2016; 85:948-59. [DOI: 10.1111/1365-2656.12528] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/19/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Nathan B. Furey
- Department of Forest and Conservation Sciences; University of British Columbia; 2424 Main Mall Vancouver BC V6T 1Z4 Canada
| | - Scott G. Hinch
- Department of Forest and Conservation Sciences; University of British Columbia; 2424 Main Mall Vancouver BC V6T 1Z4 Canada
| | - Arthur L. Bass
- Department of Forest and Conservation Sciences; University of British Columbia; 2424 Main Mall Vancouver BC V6T 1Z4 Canada
| | - Collin T. Middleton
- Department of Forest and Conservation Sciences; University of British Columbia; 2424 Main Mall Vancouver BC V6T 1Z4 Canada
| | - Vanessa Minke-Martin
- Department of Forest and Conservation Sciences; University of British Columbia; 2424 Main Mall Vancouver BC V6T 1Z4 Canada
| | - Andrew G. Lotto
- Department of Forest and Conservation Sciences; University of British Columbia; 2424 Main Mall Vancouver BC V6T 1Z4 Canada
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