New and Rare Records of Canadian Fishes and the Influence of Hydrography on Resident and Nonresident Scotian Shelf Ichthyofauna

Abstract

A recently initiated ichthyoplankton survey of the Scotian Shelf has discovered large numbers of subtropical/tropical expatriated fishes, mostly larvae, and at least two previously unrecognized populations. Thirty-three species in 25 primarily subtropical families (Carcharhinidae, Engraulidae, Synodontidae, Chlorophthalmidae, Ogcocephalidae, Antennariidae, Carapidae, Ophidiidae, Exocoetidae, Syngnathidae, Scorpaenidae, Triglidae, Dactylopteridae, Serranidae, Apogonidae, Branchiostegidae, Rachycentridae, Sciaenidae, Labridae, Scaridae, Callionymidae, Gobiidae, Bothidae, Cynoglossidae, and Ostraciontidae), seven species in four deepwater families (Gonostomatidae, Sternoptychidae, Myctophidae, and Moridae) and two gadoids are reported as new or rare records from the Canadian Atlantic. The frequency and quantity of subtropical expatriates raise the question of their ultimate fate. The existence of eastern Atlantic populations of some of these raises the possibility of transatlantic dispersal. Juvenile or adult specimens of most of the expatriated forms have not been found on the Scotian Shelf but the complex hydrography on the shelf may allow temporary habitation especially in summer. Two species, red hake and Gulf Stream flounder, appear to have discrete, self-sustaining populations on the Scotian Shelf. Both species appear to represent northernmost populations which may be living near their lower thermal limit. Discrepancies between the literature on red hake and data reported herein are unresolved and require long-term observations.Key words: Scotian Shelf, ichthyoplankton, hydrography, zoogeography, western North Atlantic