Ontogenetic shifts in the diets of juvenile Chinook Salmon: new insight from stable isotopes and fatty acids

Litz, Marisa N.C.; Miller, Jessica A.; Copeman, Louise A.; Teel, David J.; Weitkamp, Laurie A.; Daly, Elizabeth A.; Claiborne, Andrew M.

doi:10.1007/s10641-016-0542-5

Cited by 32 publications

(34 citation statements)

References 75 publications

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“…; Litz et al. ). This behavior is commonplace in subyearling salmon (Brodeur ), but digested fish were detected in only 2 of our 244 stomach samples.…”

Section: Discussionmentioning

confidence: 98%

Integrated Diet Analyses Reveal Contrasting Trophic Niches for Wild and Hatchery Juvenile Chinook Salmon in a Large River Delta

et al. 2018

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Hatchery programs have been used as a conservation tool to bolster declining populations of Chinook Salmon Oncorhynchus tshawytscha along much of the North American Pacific coast. In many watersheds, hatchery stocks are released concurrently with the wild population, thus raising the potential for density‐dependent effects. Competition for prey resources during the critical period for early marine growth and survival may diminish the foraging capacity and growth potential of wild Chinook Salmon, highlighting the importance of a diverse and productive delta habitat mosaic. We used an integrated diet approach with stomach content and stable isotope analyses to evaluate contrasting patterns of habitat use and prey consumption in a fall‐run population of juvenile Chinook Salmon from the Nisqually River delta in Puget Sound, Washington. We examined size‐class and origin‐level differences throughout a gradient of delta habitat types. Wild (unmarked) and hatchery juveniles exhibited distinct habitat use patterns whereby unmarked fish were captured more frequently in tidally influenced freshwater and mesohaline emergent marsh areas, while hatchery fish were caught more often in the nearshore intertidal zone. Consequently, hatchery fish were less likely to consume the energy‐dense terrestrial insects that were more common in freshwater and brackish marshes. Stable isotope signatures from muscle and liver tissues corroborated this finding, showing that unmarked juveniles had derived 24–31% of their diets from terrestrially sourced prey, while terrestrial insects only made up 2–8% of hatchery fish diets. This may explain why unmarked fish were in better condition than hatchery fish and had stomach contents that were 15% more energy‐rich than those of hatchery fish. We did not observe strong evidence for trophic overlap in juvenile Chinook Salmon of different rearing origins, but our results suggest that hatchery juveniles could be more sensitive to diet‐mediated effects on growth and survival.

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“…; Litz et al. ). This behavior is commonplace in subyearling salmon (Brodeur ), but digested fish were detected in only 2 of our 244 stomach samples.…”

Section: Discussionmentioning

confidence: 98%

Integrated Diet Analyses Reveal Contrasting Trophic Niches for Wild and Hatchery Juvenile Chinook Salmon in a Large River Delta

et al. 2018

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“…Supplementary otolith samples were collected from salmon in September 2011 between La Push, Washington (47°55′) and Newport, Oregon (44°40′). We also collected potential salmon prey in 36 surface trawls from July through September of each year using a 264 Nordic rope trawl (NET Systems, Bainbridge Island, Washington) with 3‐mm mesh in the cod end (Litz, Miller, Copeman, Teel et al., ). Juvenile salmon used in the study ( n = 514) were assigned to the UCSF genetic stock based on genotyping of 13 microsatellite DNA loci following Teel et al.…”

Section: Methodsmentioning

confidence: 99%

“…Juvenile salmon used in the study ( n = 514) were assigned to the UCSF genetic stock based on genotyping of 13 microsatellite DNA loci following Teel et al. () and classified as subyearlings based on FL (Litz, Miller, Copeman, Teel et al., ; Weitkamp et al., ).…”

Section: Methodsmentioning

confidence: 99%

Energy dynamics of subyearling Chinook salmon reveal the importance of piscivory to short‐term growth during early marine residence

Litz

Miller

Brodeur

et al. 2018

Fisheries Oceanography

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Variation in prey quantity and quality can influence growth and survival of marine predators, including anadromous fish that migrate from freshwater systems. The objective of this study was to examine the energy dynamics of subyearling Chinook salmon (Oncorhynchus tshawytscha) following freshwater emigration. To address this objective, a population of Chinook salmon and their marine prey were repeatedly sampled from June to September over 2 years in coastal waters off Oregon and Washington. Subyearlings from the same population were also reared under laboratory conditions. Using a bioenergetics model evaluated in the laboratory, we found that growth rate variability in the field was associated more with differences in northern anchovy (Engraulis mordax) consumption and less with variation in diet energy density or ocean temperature. Highest growth rates (2.43–3.22% body weight/day) occurred in months when anchovy biomass peaked, and the timing of peak anchovy biomass varied by year. Our results support a general pattern among subyearling Chinook salmon occurring from Alaska to California that feeding rates contribute most to growth rate variability during early marine residence, although dominant prey types can differ seasonally, annually, or by ecosystem. In the northern California Current, faster growth appears to be associated with the availability of age‐0 anchovy. Identifying factors that influence the seasonal development of the prey field and regulate prey quantity and quality will improve understanding of salmon growth and survival during early marine residence.

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“…On the other hand, differences observed over time within an individual represent trait variation emerging from environmental variability or biological processes, such as phenology or sexual maturity (van de Pol & Wright, ). Between‐individual variability in traits has been found across a wide range of species, including arthropods (Jackson et al, ), amphibians (Araújo, Bolnick, Martinelli, Giaretta, & Reis, ), reptiles (Vander Zanden, Bjorndal, & Bolten, ), birds (Cherel, Quillfeldt, Delord, Weimerskirch, & Inger, ), mammals (Novak & Tinker, ) and fish (Litz et al, ). However, little is known on the respective contribution and temporal consistency of between‐ and within‐individual effects on the variability of trophic traits at the level of population and species (Novak & Tinker, ).…”

Section: Introductionmentioning

confidence: 99%

Within‐individual trophic variability drives short‐term intraspecific trait variation in natural populations

Musseau

Vincenzi

Santoul

et al. 2020

Journal of Animal Ecology

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Intraspecific trait variability (ITV) maintains functional diversity in populations and communities, and plays a crucial role in ecological and evolutionary processes such as trophic cascades or speciation. Furthermore, functional variation within a species and its populations can help buffer against harmful environmental changes. Trait variability within species can be observed from differences among populations, and between‐ and within individuals. In animals, ITV can be driven by ontogeny, the environment in which populations live and by within‐individual specialization or variation unrelated to growth. However, we still know little about the relative strength of these drivers in determining ITV variation in natural populations. Here, we aimed to (a) measure the relative strength of between‐ and within‐individual effects of body size on ITV over time, and (b) disentangle the trophic changes due to ontogeny from other sources of variability, such as the environment experienced by populations and individual preferences at varying temporal and spatial scales. We used as a model system the endangered marble trout Salmo marmoratus, a freshwater fish living in a restricted geographical area (<900 km2) that shows marked changes in diet through ontogeny. We investigated two trophic traits, trophic position and resource use, with stable isotopes (δ15N and δ13C), and followed over time 238 individually tagged marble trout from six populations to estimate the trophic changes between and within individuals through ontogeny at three different time‐scales (short term: 3 months, medium term: 1 year and long term: 2 years). We found that the relative strength of between‐ and within‐individual effects of body size on trophic position and resource use change strongly over time. Both effects played a similar role in ITV over medium‐ and long‐term time‐scales, but within‐individual effects were significantly driving trophic variability over short‐term scales. Apart from ontogenetic shifts, individuals showed variability in trophic traits as big as the variability estimated between populations. Overall, our results show how the relative strengths of ITV drivers change over time. This study evidences the crucial importance of considering effects of time‐scales on functional variability at individual, population and species levels.

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Ontogenetic shifts in the diets of juvenile Chinook Salmon: new insight from stable isotopes and fatty acids

Cited by 32 publications

References 75 publications

Integrated Diet Analyses Reveal Contrasting Trophic Niches for Wild and Hatchery Juvenile Chinook Salmon in a Large River Delta

Integrated Diet Analyses Reveal Contrasting Trophic Niches for Wild and Hatchery Juvenile Chinook Salmon in a Large River Delta

Energy dynamics of subyearling Chinook salmon reveal the importance of piscivory to short‐term growth during early marine residence

Within‐individual trophic variability drives short‐term intraspecific trait variation in natural populations

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