Egg size and lipid content of lake trout (<i>Salvelinus namaycush</i>) in the wild and in captivity

Johnston, Thomas A.

doi:10.1139/cjfas-2017-0408

Cited by 9 publications

(7 citation statements)

References 89 publications

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“…In captive breeding, relaxed selection on embryos could give females with many small eggs an evolutionary advantage over females with few large eggs. This could lead to an evolutionary response and thereby decrease in mean egg size over time (Heath et al, 2003; Johnston, 2018). Our results suggest that such an evolutionary response would lead to smaller juveniles over time.…”

Section: Discussionmentioning

confidence: 99%

Growth of brown trout in the wild predicted by embryo stress reaction in the laboratory

Bylemans

Cunha

Wilkins

et al. 2022

Preprint

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Laboratory studies on embryos of salmonids, such as the brown trout (Salmo trutta), have been used extensively to study factors influencing offspring performance. These studies are based on the implicit assumption that early life-history traits are relevant for growth and survival in the wild. Here we tested this assumption. We used gametes of wild-caught brown trout to perform a block-wise full-factorial breeding experiment, with some of the resulting offspring we carried out controlled laboratory experiments, and released the remaining offspring into a natural streamlet. We recaptured 0+ juveniles after their first summer in the wild and used microsatellite and sex-linked markers to determine sex-specific growth and survival for each of the 60 experimental families. We also recorded mean egg size and carotenoid content per female to evaluate their importance for juvenile growth and survival. We found strong correlations between laboratory performance and growth, but not survival, of 0+ juveniles in the wild. Egg size positively influenced juvenile growth. We also found that male juveniles grew faster than females. Juvenile survival seemed not influenced by egg size, but we observed a significant male-biased survival for eggs with a high zeaxanthin content (a carotenoid). This first observation suggests that female reproductive strategies can have sex-specific effects that need to be better understood. We conclude that embryo performance in controlled environments (laboratory or hatchery) can be useful predictors of offspring growth in a natural setting.

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Section: Discussionmentioning

confidence: 99%

Growth of brown trout in the wild predicted by embryo stress reaction in the laboratory

Bylemans

Cunha

Wilkins

et al. 2022

Preprint

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“…The first is that the observed differences between juveniles from the two populations reared in the common garden study may be the result of differing parental effects, in which the parents' phenotypes influence those of offspring beyond the direct effects of genes (Räsänen and Kruuk 2007). This may take the form of gamete provisioning, in which the size, lipid content and/ or fatty acid composition of ova can play a role in eventual alevin phenotype and fitness (Wiegand et al 2007;Johnston 2018;Shaw et al 2018). Alternatively, transgenerational epigenetic effects may be responsible for the divergent phenotypes.…”

Section: Discussionmentioning

confidence: 99%

Differential selection pressures result in a rapid divergence of donor and refuge populations of a high conservation value freshwater fish Coregonus lavaretus (L.)

et al. 2019

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As a conservation measure to protect European whitefish in Scotland, a translocated population was established in Loch Sloy from Loch Lomond stock between 1988 and 1990. Previous study has assumed that current morphological differences between adults from the donor and refuge lakes have arisen through phenotypic plasticity. The present study compared the morphologies of whitefish at three life stages: alevins and fry raised in a common garden, and wild-caught adults. Alevins were clearly distinguishable by their lake of origin. Loch Sloy alevins were distinguishable also by family, although this was not the case for Loch Lomond. Differential allometric trajectories facilitated the persistence of morphological differences associated with lake of origin through the fry stage into adulthood. Overall, the whitefish from Loch Lomond displayed morphologies associated with pelagic feeders, while the more robust heads and ventrally positioned snouts of the Loch Sloy whitefish conformed to expectations for more benthic feeding habits. That differences between populations were present not only in wild adults, but also in alevins and fry from a common garden setup, strongly suggests that the divergence between populations is due to inheritance mechanisms, rather than differential plastic responses, and questions the effectiveness of translocation as a conservation measure.

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“…For example, several studies have associated rapid growth with more numerous, but smaller, eggs for fish of a given length (Bagenal, 1969; Morita et al, 1999). Conversely, Johnston (2018) found that faster‐growing female lake trout ( Salvelinus namaycush ) tended to produce larger eggs. Density‐dependent growth links the size of individuals to population density, and because smaller fish produce fewer eggs, the effect can propagate back to the population level (Watson et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Closing the life‐history loop: Density effects on fecundity and egg size of an exploited, amphidromous fish (Galaxias maculatus) in freshwater protected areas

2023

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1. Understanding how fecundity and egg size respond to density-dependent and density-independent processes is essential for fisheries assessments because it shows managers how exploited populations respond to fishery closures. Similarly, the extent to which density-dependent and density-independent processes influence fecundity and egg size in freshwater protected areas (FPAs) is important for determining their conservation potential and effectiveness as a fisheries enhancement strategy.2. The fecundity and egg size of 164 sexually mature Galaxias maculatus females collected from coastal waterways on the West Coast of New Zealand's South Island were determined from a combination of techniques. Specifically, the additive and interactive effects of density, temperature, and body size on fecundity and egg size were examined in 10 G. maculatus populations across a density gradient mediated by fishery closures and tested for an egg size/fecundity trade-off.3. There was no evidence of an egg size/fecundity trade-off, or of negative densitydependent effects on fecundity or egg size within FPAs. Egg size, gonadosomatic index, and water temperature were correlated with latitude.4. Fecundity increased with body size, but egg size did not. This highlights the importance of available forage (terrestrial-and stream-based prey) for G. maculatus to maintain individual growth to increase egg production and larval export derived from no-take FPAs.5. For the current network of no-take FPAs to be more effective as a management tool, efforts should focus on the remediation of in-stream and requisite riparian spawning habitats, the degradation of which has caused population bottlenecks for this culturally and economically important amphidromous species. The major subsidy from FPAs for the G. maculatus metapopulation is sustainable egg production if migration to sea of the greatest possible number of larvae can be ensured.

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Egg size and lipid content of lake trout (Salvelinus namaycush) in the wild and in captivity

Cited by 9 publications

References 89 publications

Growth of brown trout in the wild predicted by embryo stress reaction in the laboratory

Growth of brown trout in the wild predicted by embryo stress reaction in the laboratory

Differential selection pressures result in a rapid divergence of donor and refuge populations of a high conservation value freshwater fish Coregonus lavaretus (L.)

Closing the life‐history loop: Density effects on fecundity and egg size of an exploited, amphidromous fish (Galaxias maculatus) in freshwater protected areas

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