Research Document - 2006/093

Distribution, Abundance, and Life History of Malacoraja senta (Smooth Skate) in Canadian Atlantic Waters With Reference to its Global Distribution

By Kulka, D.W., D. Swain, M.R. Simpson, C.M. Miri, J. Simon, J. Gauthier, R. McPhie, J. Sulikowski and L. Hamilton

Abstract

Under the Canadian Species At Risk Act (SARA), the Committee On the Status of Endangered Wildlife In Canada (COSEWIC) is responsible for assessing extinction risk of terrestrial and aquatic species that occur within Canada including in the surrounding oceans within jurisdictional limits. As part of the initial process of assessing extinction risk for an aquatic species, the Department of Fisheries and Oceans Canada examines pertinent data for which they are the custodian. Available information is reviewed regarding the taxonomy, distribution, abundance, life history and ecology of Malacoraja senta (Smooth skate) in Canadian Atlantic shelf waters as well as anthropogenic influences. Our study also includes adjacent USA waters to encompass the global range of the species. M. senta ranges from Lat. 40°, southern Georges Bank to Lat. 56.5° in the Hopedale Channel on the Labrador Shelf. It most commonly occurs in the troughs separating banks within a depth range of 70-480 m, considerably shallower than it four congeners. It commonly occupies a temperature range of 2.7-10° C, seldom found in <0° C. It occupied 585,000 km2 (total area where it was observed between 1971 and 2005). It occurred in five distinct areas (treated here as Designatable Units or DU’s) separated by large areas where none were observed. It is uncertain whether the five DU’s constituted separate reproductive, genetically distinct units. Each of the five concentrations underwent changes in abundance to varying degrees and the largest decline occurred in the Funk Island Deep.

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