Impact of egg fatty acid signatures on embryo viability in wild and domesticated cisco

Jacques Rinchard (SUNY Brockport, jrinchar@brockport.edu); Gordon Roger (FWS); Meredith Bartron (FWS); Steve Davis (FWS); John Sweka (FWS)

One of the major challenges in the aquaculture of bloater (Coregonus hoyi) and cisco (Coregonus artedi) is the low survival rate of larvae from hatchery-reared broodstock compared to wild broodstock. Percent eye-up of bloater eggs from parents fed different diets at different facilities were below 25%, whereas percent survival from eyed egg to hatch of bloater ranged from 36 to 94% (Sweka et al. 2024). Similarly, survival of eggs from wild lake whitefish (C. shinzi palea) was higher that of hatchery-reared females (Gillet 1991). Several factors could contribute to this issue, but one significant reason could be attributed to the quality of the eggs, particularly in terms of their fatty acid balance. In their natural habitat, wild bloater and cisco have access to a diverse diet composed of invertebrates and small fish, providing them with a well-rounded intake of essential nutrients and fatty acids. In contrast, fish reared in hatcheries receive formulated feeds that may not perfectly replicate the nutritional profile of a wild diet. These feeds might lack certain essential fatty acids or may not provide them in the optimal ratios required for the best possible larval development and survival. For example, egg fatty acid signatures of wild bloater differed significantly from the ones reared in captivity and fed Biobrood, a custom diet, or Otohime-krill (Sweka et al. 2024). The primary objective of this project is to improve the productivity of captive broodstock by examining the fatty acid signatures of cisco eggs from wild and captive populations. By analyzing fatty acids from both neutral lipid and phospholipid classes, we aim to determine how different levels of fatty acids influence embryo viability, thereby enhancing our understanding of the nutritional and reproductive requirements of cisco broodstock in aquaculture. Cisco were selected for this study because wild females are more readily available and their rearing is generally easier than bloater. Should this project provide further support that fatty acid imbalance is limiting survival of embryos from brood stock, we would propose additional work for bloater.