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Simmons OM, Britton JR, Gillingham PK, Nevoux M, Riley WD, Rivot E, Gregory SD. Predicting how environmental conditions and smolt body length when entering the marine environment impact individual Atlantic salmon Salmo salar adult return rates. JOURNAL OF FISH BIOLOGY 2022; 101:378-388. [PMID: 34773399 DOI: 10.1111/jfb.14946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 11/02/2021] [Accepted: 11/08/2021] [Indexed: 06/13/2023]
Abstract
Populations of Atlantic salmon Salmo salar have experienced precipitous declines in abundance since the 1970s. This decline has been associated with reduced numbers of adult salmon returning to fresh water from their marine migration, i.e., their marine return rates (MRR). Thus, understanding the factors that affect MRR is of crucial conservation importance. The authors used a state-space model with a 13-year time series of individually tagged salmon mark-recapture histories on the River Frome, southern England, to test the effect of smolt body length on their MRR. In addition to smolt length, the model tested for the influence of environmental covariates that were representative of the conditions experienced by the smolts in the early stages of their seaward migration, i.e., from the lower river to the estuary exit. The model indicated that, even when accounting for environmental covariates, smolt body length was an important predictor of MRR. Although larger smolts have a higher probability of returning to their natal river as adults than smaller smolts, and one-sea-winter salmon have a survival rate twice as high as multi-sea-winter salmon, the actual biological mechanisms underpinning this phenomenon remain uncertain. These results have important applications for salmon conservation, as efforts to bolster salmon populations in the freshwater environment should consider methods to improve smolt quality (i.e., body size) as well as smolt quantity.
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Affiliation(s)
- Olivia Meredith Simmons
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK
- Salmon and Trout Research Centre, Game and Wildlife Conservation Trust, Wareham, UK
| | - J Robert Britton
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK
| | - Phillipa K Gillingham
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK
| | - Marie Nevoux
- DECOD, Ecosystem Dynamics and Sustainability, Institut Agro, INRAE, Ifremer, Rennes, France
- MIAME-Management of Diadromous Fish in Their Environment, OFB, INRAE, Institut Agro, Univ Pau & Pays Adour/E2S Uppa, Rennes, France
| | - William D Riley
- The Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, UK
| | - Etienne Rivot
- DECOD, Ecosystem Dynamics and Sustainability, Institut Agro, INRAE, Ifremer, Rennes, France
- MIAME-Management of Diadromous Fish in Their Environment, OFB, INRAE, Institut Agro, Univ Pau & Pays Adour/E2S Uppa, Rennes, France
| | - Stephen D Gregory
- Salmon and Trout Research Centre, Game and Wildlife Conservation Trust, Wareham, UK
- The Centre for Environment, Fisheries and Aquaculture Science, Weymouth, UK
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Spanjer AR, Gendaszek AS, Wulfkuhle EJ, Black RW, Jaeger KL. Assessing climate change impacts on Pacific salmon and trout using bioenergetics and spatiotemporal explicit river temperature predictions under varying riparian conditions. PLoS One 2022; 17:e0266871. [PMID: 35594277 PMCID: PMC9122258 DOI: 10.1371/journal.pone.0266871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 03/29/2022] [Indexed: 11/18/2022] Open
Abstract
Pacific salmon and trout populations are affected by timber harvest, the removal and alteration of riparian vegetation, and the resulting physical changes to water quality, temperature, and associated delivery of high-quality terrestrial prey. Juvenile salmon and trout growth, a key predictor of survival, is poorly understood in the context of current and future (climate-change mediated) conditions, with resource managers needing information on how land use will impact future river conditions for these commercially and culturally important species. We used the Heat Source water temperature modeling framework to develop a spatiotemporal model to assess how riparian canopy and vegetation preservation and addition could influence river temperatures under future climate predictions in a coastal river fed by a moraine-dammed lake: the Quinault River in Washington State. The model predicted higher water temperatures under future carbon emission projections, representative concentration pathway (RCP) 4.5 and 8.5, with varying magnitude based on different riparian vegetation scenarios. We used the daily average temperature output from these scenarios to predict potential juvenile fish growth using the Wisconsin bioenergetics model. A combination of riparian vegetation removal and continued high carbon emissions resulted in a predicted seven-day average daily maximum temperature (7DADM) increase of 1.7°C in the lower river by 2080; increases in riparian shading mitigate this 7DADM increase to only 0.9°C. Under the current thermal regime, bioenergetics modeling predicts juvenile fish lose weight in the lower river; this loss of potential growth worsens by an average of 20–83% in the lower river by 2080, increasing with the loss of riparian shading. This study assess the impact of riparian vegetation management on future thermal habitat for Pacific salmon and trout under warming climates and provide a useful spatially explicit modeling framework that managers can use to make decisions regarding riparian vegetation management and its mechanistic impact to water temperature and rearing juvenile fish.
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Affiliation(s)
- Andrew R. Spanjer
- U.S. Geological Survey, Washington Water Science Center, Tacoma, WA, United States of America
- * E-mail:
| | - Andrew S. Gendaszek
- U.S. Geological Survey, Washington Water Science Center, Tacoma, WA, United States of America
| | - Elyse J. Wulfkuhle
- Department of Natural Resources, Quinault Indian Nation, Taholah, WA, United States of America
| | - Robert W. Black
- U.S. Geological Survey, Washington Water Science Center, Tacoma, WA, United States of America
| | - Kristin L. Jaeger
- U.S. Geological Survey, Washington Water Science Center, Tacoma, WA, United States of America
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Thomas K, Hansen T, Brophy D, Ó Maoiléidigh N, Fjelldal PG. Experimental investigation of the effects of temperature and feeding regime on scale growth in Atlantic salmon Salmo salar post-smolts. JOURNAL OF FISH BIOLOGY 2019; 94:896-908. [PMID: 30887504 DOI: 10.1111/jfb.13971] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
Salmo salar post-smolts were reared in seawater under controlled laboratory conditions for 12 weeks. The fish were exposed to three constant temperature treatments (15, 10.5 and 6°C) and four feeding treatments (constant feeding, food withheld for 7 days, food withheld for 14 days and food withheld intermittently for four periods of 7 days). Scale growth was proportional to fish growth across all treatments, justifying the use of scale measurements as a proxy for growth during the early marine phase. The rate of circuli deposition was dependant on temperature and feeding regime and was generally proportional to fish growth but with some decoupling of the relationship at 15°C. Deposition rates varied from 4.8 days per circulus at 15°C (constant feeding) to 15.1 days per circulus at 6°C (interrupted feeding). Cumulative degree day (° D) was a better predictor of circuli number than age, although the rate of circuli deposition ° D-1 was significantly lower at 6°C compared with 15 and 10.5°C. Inter-circuli distances were highly variable and did not reflect growth rate; tightly packed circuli occurred during periods without food when growth was depressed, but also during periods of rapid growth at 15°C. The results further current understanding of scale growth properties and can inform investigations of declining marine growth in S. salar based on interpretations of scale growth patterns.
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Affiliation(s)
- Katie Thomas
- Department of Natural Sciences, Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland
- Fisheries and Ecosystems Advisory Services, Marine Institute, Furnace, Newport, Co. Mayo, Ireland
| | - Tom Hansen
- Reproduction and growth research group, Institute of Marine Research, Matre Aquaculture Research Station, Matredal, Norway
| | - Deirdre Brophy
- Department of Natural Sciences, Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Galway, Ireland
| | - Niall Ó Maoiléidigh
- Fisheries and Ecosystems Advisory Services, Marine Institute, Furnace, Newport, Co. Mayo, Ireland
| | - Per Gunnar Fjelldal
- Reproduction and growth research group, Institute of Marine Research, Matre Aquaculture Research Station, Matredal, Norway
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