Is gonadal investment in walleye (Sander vitreus) dependent on body lipid reserves? A multipopulation comparative analysis

Abstract

A key requirement of effective fisheries management is a better understanding of the mechanisms driving recruitment variability. Recent research suggests that the quantity and quality of gametes produced by fish is closely linked to the availability of surplus energy, usually stored as lipid. We sampled mature walleye (Sander vitreus) from seven populations across Canada to determine if indices of reproductive effort were positively related to indices of adult nutrient reserves, primarily body lipid concentration. Populations varied greatly in growth rates, body lipid contents, and reproductive traits. Within-population trends between indices of reproductive effort and parental body traits were highly variable. Body lipid concentration was most closely related to gonad lipid concentration, but not in all populations. Among populations, relative fecundity and ovary lipid concentrations were positively related, and egg size was negatively related to whole-body lipid concentrations; no trends were evident for males. Our results suggest that relationships between walleye reproductive effort and body lipid reserves may be more complex than previously thought.