| ONTOGENETIC DEVELOPMENT OF THE ENDANGERED ATLANTIC WHITEFISH (COREGONUS HUNSTMANI SCOTT, 1987) EGGS, LARVAE, AND JUVENILES |
| HASSELMAN, D.J. Gene Probe Lab, Dalhousie University, Halifax, NS, Canada, B3H 4J1, dhasselm@dal.ca;
Whitelaw, J., Department of Fisheries and Oceans; Mersey Biodiversity Facility, Milton, NS, Canada, B0T 1P0, WhitelawJ@mar.dfo-mpo.gc.ca;
Bradford R.G. Department of Fisheries and Oceans; Bedford Institute of Oceanography, P.O. Box 1006, 1 Challenger Drive, Dartmouth, NS, Canada, B2Y 4A2, BradfordR@mar.dfo-mpo.gc.ca |
| Atlantic whitefish (Coregonus huntsmani) are an endangered species endemic to Canada, and are known historically from only two watersheds in Nova Scotia. The species has received relatively little study, and their early life history stages have not been previously described. Such information is required to support several recovery actions (e.g. identification of critical habitat, assessment of threats, further definition of their global distribution, etc.) under the federal Species at Risk Act (SARA). We first 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 (C. clupeaformis) and cisco (C. artedii)) to i) identify ontogenetic differences that may facilitate field identification, ii) determine whether interspecific phenotypic 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 phenotypic differences were observed at all ontogenetic stages, several of which may serve as valuable field identification criteria. Evidence for heterochrony during embryogenesis, and 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. |
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