Ontogenetic development of the endangered Atlantic whitefish (Coregonus huntsmaniScott, 1987) eggs, embryos, larvae, and juveniles

Abstract

Atlantic whitefish ( Coregonus huntsmani Scott, 1987 ) are an endangered species endemic to Canada and are known only from Nova Scotia. Information concerning their early life-history stages — not previously described — is required to support several recovery actions under the federal Species at Risk Act (SARA). We describe the ontogenetic development of Atlantic whitefish eggs, larvae, and juveniles acquired through captive-mating of wild-caught adults, following criteria established for fishes in general and for other North American coregonine species where possible. We then conduct interspecific comparisons between Atlantic whitefish and the two most closely phylogenetically related species (i.e., lake whitefish ( Coregonus clupeaformis (Mitchill, 1818)) and cisco ( Coregonus artedii Lesueur, 1818)) to (i) identify ontogenetic differences that may facilitate field identification, (ii) determine whether differences at common ontogenetic milestones reinforce the recognition of Atlantic whitefish at the species level, and (iii) comment on whether these differences are consistent with the putative ancestral status of Atlantic whitefish. Interspecific differences were observed at all ontogenetic stages, several of which may serve as field identification criteria. Evidence for heterochrony during embryogenesis, as well as interspecific differences in egg size, myomere counts, and pigmentation patterns, substantiate the recognition of Atlantic whitefish as a valid species and support its putative ancestral status.