Body shape and fin size in juvenile Atlantic salmon (Salmo salar): effects of temperature during embryogenesis

Abstract

Temperature during egg incubation and early development influences later life stages of fishes, potentially influencing survival. Throughout its distribution, Atlantic salmon (Salmo salar Linnaeus, 1758) have experienced population declines, and in view of ongoing global warming, we tested if temperature during the earliest developmental stages modified body shape and fin size when temperatures averaged 2.6 vs. 5.6 °C. This temperature difference simulates increases predicted in climate change scenarios. Based on previous studies, we hypothesized that salmon originating from eggs subjected to cold incubation temperatures would have slimmer bodies and larger pectoral and dorsal fins than salmon from eggs that experienced warmer temperatures. After hatching, the juveniles were raised for 1 year under identical temperatures, after which we measured their body shape and fin areas. We found no support for our hypothesis regarding body shape. Indeed, we found the opposite, with cold-incubated salmon having deeper bodies than warm-incubated salmon. For fin size, the pectoral fins of cold-incubated salmon were larger than for warm-incubated salmon as predicted, but there was no difference in dorsal fin size. These results suggest that global warming may lead to altered body shape and fin size, possibly affecting swimming performance, and thus raise questions about the ecological consequences of the changes.

Egg incubation temperature influences the population‐specific outmigration rate of juvenile brown troutSalmo trutta

“…But this may not only result from differences in growth. Greenberg et al (2021) observed that 1-year-old juveniles of S. salar incubated as eggs in heated water had a slimmer, more smolt-like body shape than similar-sized S. salar offspring that were produced from colder eggs.…”

“…Greenberg et al . (2021) observed that 1‐year‐old juveniles of S. salar incubated as eggs in heated water had a slimmer, more smolt‐like body shape than similar‐sized S. salar offspring that were produced from colder eggs. This may suggest that the warm offspring were ready for migration younger and smaller than those incubated in colder water.…”

Differences in growth between offspring of anadromous and freshwater brown troutSalmo trutta

“…(2017) reported that the populations of R. temporaria from temporary pools had a higher degree of developmental plasticity than tadpoles of the same species from permanent pools. In contrast, juvenile S. salar incubated as eggs in warm water (7°C) were slimmer than conspecifics incubated in cold water (3°C) (Greenberg et al ., 2021), showing another difference between S. trutta and S. salar .…”

Modelling the impact of replacing fish oil with plant oils: A meta‐analysis to match the optimal plant oil for major cultured fish

“…Indeed, Greenberg et al have found that the temperature at the early life stages of Atlantic salmon could influence its shape afterwards. 369 Thus, factors like FM content and water temperature could be used to shape the appearance of fish and to neutralize the impact caused by changes in FO content and FA profile. Moreover, the effect sizes of many parameters changed more when the duration of experiments was longer for Atlantic salmon, whereas for other species such as European seabass and Gilthead seabream, long-term experiments allowed them to adapt to plant oils and eliminated the variation in effect sizes.…”