Research Document - 2011/116

Distribution, abundance, and life history of smooth skate (Malacoraja senta Garman 1885) in Northwest Atlantic waters

By M.R. Simpson, L.G.S. Mello, C.M. Miri, M. Treble, and T. Siferd

Abstract

Decline in abundance and reduction in the extent of distribution have been observed in several Smooth Skate (Malacoraja senta Garman 1885) populations inhabiting Canadian waters, despite no directed commercial fisheries for this species. This paper presents the most recent information regarding the distribution and abundance of M. senta in Newfoundland and Labrador waters, and includes available data from adjacent and Arctic waters. The primary purpose of this paper is to provide this information to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) for use in formulating and evaluating conservation and management strategies for this species in terms of risk of extinction.

Independent data series based on spring and fall bottom trawl survey catches and commercial fisheries statistics covering the distribution of M. senta in NAFO Div. 2HJ3KLMNOPs indicate that this species is comprised of several geographically distinct and persistent concentrations (each referred to here as a designatable unit or DU). These concentrations have experienced different trajectories in terms of abundance and distribution trends, but also have displayed common features such as thermal preferences and size-dependent distributions. The main concentration was centered in Div. 2J3K (Funk Island Deep DU) until the 1980s, but experienced substantial declines in abundance (juveniles and adults) and area of occupancy thereafter; although some population recovery has been detected since the mid-2000s. Two other smaller skate concentrations located in Div. 2H (Hopedale Channel DU) and Div. 3M (Flemish Cap DU) displayed spatio-temporal trends similar to those observed in the Funk Island Deep DU. In contrast, M. senta located in Div. 3OPs (Laurentian Channel DU) displayed relatively stable trends in abundance and distribution, and increasing trends have been detected during the last decade.

Several aspects of M. senta status in Newfoundland and Labrador waters remain uncertain; largely due to partial knowledge of population structure and biology, as well as the impacts of commercial fisheries and environmental variability.

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