Comparison of ovum lipid provisioning among lake whitefish, walleye and northern pike co-habiting in Bay of Quinte (Lake Ontario, Canada)

Abstract

We compared size, total lipid contents, percent of lipids as neutral lipids and fatty acid profiles of ova from Bay of Quinte (Lake Ontario) populations of lake whitefish and northern pike to previously reported data from Bay of Quinte walleye. We also assessed how the relationships between ovum lipid fatty acid composition and maternal size or age varied among these species. Ovum size, total lipid content and percent neutral lipid differed among the three species and in general were not influenced by maternal size or age. The highest percentage of neutral lipid occurred in walleye ova and the lowest in northern pike. Principal components analysis revealed significant separation of fatty acid profiles among the three species, with greater differences in the neutral lipids than in the polar lipids. Lake whitefish were more distinct from the walleye and northern pike than the walleye and northern pike were from each other in the neutral lipids. Lake whitefish ova had higher percentages of eicosapentaenoic acid (EPA) in both lipid fractions than those of the other two species. In direct contrast to the previously observed trends in walleye, percentages of arachidonic acid and docosahexaenoic acid decreased while those of EPA increased with maternal size in the lake whitefish. None of the major fatty acids in northern pike ova varied significantly with maternal size or age. Our study reveals that the Bay of Quinte populations of the three species have different patterns of allocation of fatty acids to ova as they grow and age.