Revealing the relationship between feeding and growth of larval redfish (Sebastes sp.) in the Gulf of St. Lawrence

Abstract

Year-class strength of fish stocks is often set during the larval stage, with fast growth being a favourable factor leading to strong recruitment. Following 30 years of poor recruitment, redfish (Sebastes sp.) in the Gulf of St. Lawrence (GSL) produced unprecedentedly strong year classes in 2011–2013. The relationship between larval diet and growth that potentially drove these successful recruitment events is unknown. Gut content and otolith microstructure of redfish larvae collected from the GSL in 1999 and 2000 were analysed in order to understand the relationship between recent feeding success and growth in larval redfish, and identify feeding behaviours that are associated with fast growth. Growth was positively correlated with larval body depth (BD), which was used as a morphological proxy for growth. Prey type and size were the best explanatory variables of larval BD after obligatory first-feeding. Larvae that consumed large naupliar stages of frequently consumed copepod taxa were deeper-bodied and grew more quickly than larvae that consumed redfish's preferred prey, Calanus finmarchicus eggs. Warming GSL waters have shifted the phenology of commonly consumed prey taxa earlier in the season, which may increase the overlap between redfish and naupliar prey that drive fast growth, survival, and potentially recruitment success.

Revisiting the role of early life growth for survival potential in three clupeoid species

“…The growth autocorrelation values have been reported to vary in different ecosystems and cohorts within a given species (Pepin et al, 2015). Therefore, the trends of growth autocorrelation investigated so far (Burns et al, 2021; Pepin et al, 2001, 2015; Primo et al, 2021; Robert, Pepin, et al, 2014) may not cover the full variability range for some of the species. In contrast, based on the substantial sardine and anchovy sample sizes originating from a wide range of environmental conditions, the growth autocorrelations presented in our study are likely representative of trends at the species level.…”

“…We adopted the group-level growth autocorrelation analysis approach following Burns et al (2021), Pepin et al (2001Pepin et al ( , 2015, Primo et al (2021), andRobert, Pepin, et al (2014) to determine speciesrepresentative patterns of the effects of growth rates at a given age on later growth potential. The otolith radius (x) and SL (y) were highly correlated as allometric relationships for sardine (y = 2.699x 0.433 , n = 1126, r = 0.964, p < 0.001) and anchovy (y = 1.789x 0.504 , n = 3424, r = 0.924, p < 0.001).…”

“…Growth autocorrelation analysis has previously been applied to a total of 12 different species across various ecosystems (Burns et al, 2021;Pepin et al, 2001Pepin et al, , 2015Primo et al, 2021;Robert, Pepin, et al, 2014), but not in small pelagic fish, except for Atlantic mackerel Scomber scombrus. In the present study, we examined growth autocorrelation for three different clupeoid species: sardine, anchovy, and round herring.…”

“…Thus, under high growth autocorrelation, early feeding success and growth rate will have a substantial effect on survival potential during subsequent life stages (as suggested by Robert, Pepin, et al, 2014;Pepin et al, 2015). Recent studies looked into otolith-derived growth autocorrelation based on otolith daily increment width data to test such effects of growth rates in the life history of fish (Burns et al, 2021;Pepin et al, 2001Pepin et al, , 2015Primo et al, 2021;Robert, Pepin, et al, 2014). This method allows visualizing the extent to which growth rate achieved at a given age influences subsequent growth rates at an older age.…”

Occurrence and behavioral rhythms of the endangered Acadian redfish (Sebastes fasciatus) in the Sambro Bank (Scotian Shelf)

“…In 2010, the Canadian Committee on the Status of Endangered Wildlife designated the population of S. fasciatus in the area as 'Threatened', and S. mentella as 'Endangered' (Benestan et al, 2021). However, demonstrative of the extreme nature of population fluctuations in these species, unprecedently strong recruitment of S. mentella, from very low population abundance, occurred in the Gulf of St. Lawrence from 2011(Burns et al, 2021. Survivorship was high, resulting in massive population increases and record-breaking biomass today.…”