Winter Skate (Leucoraja Ocellata)
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- List of Figures
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status
- Summary of Status Report
- Technical Summary
- Acknowledgements, Authorities Contacted, and Information Sources
- Biographical Summary of Report Writer
The winter skate is a benthic species closely confined to sandy or gravelly bottoms, usually in depths less than 111 m (Scott and Scott, 1988), although they have been caught at depths approaching 400 m; research vessel survey data show that more than 90% of specimens are caught in less than 150 m of water. In the southern Gulf, winter skate can occupy very shallow depths in late summer/early autumn; the median depth at which winter skate are captured in DFO’s September research surveys is about 30 m. On the Scotian Shelf, Scott and Scott (1998) indicate a preferred depth of 37–90 m.
Winter skate have been reported in waters ranging between -1.2°and 19° C. In the Southern Gulf, the average temperature occupied by winter skate during the September survey has varied between 5.8°and 12.4° C (D. P. Swain, Department of Fisheries and Oceans, PO Box 5030, Moncton, NB, unpublished data). Elsewhere, temperatures at depth of capture have been reported to be 1.1°to 12.7° C off eastern Nova Scotia and 2°to 15° C from southern Nova Scotia to Cape Hatteras. On the Scotian Shelf, they are most frequently found at depths where temperatures range between 5°and 9° C (Collette and Klein-MacPhee, 2002). The salinity of the waters inhabited by skate typically ranges between 32.0‰ and 34.4‰; some individuals may be exposed to salinities as low as 29 ‰ in the southern Gulf of St. Lawrence (Bigelow and Schroeder, 1953).
Winter skate have been termed a « winter periodic” because their seasonal migration suggests a preference for cool temperatures (Tyler, 1971). Winter skate tend to withdraw from very shallow waters along southern New England in early summer when the temperature has risen to 18-19° C and to reappear there and near New York in early autumn (Bigelow and Schroeder, 1953). Winter skate are present inshore regularly during summer in Passamaquoddy Bay at the entrance to the Bay of Fundy, in Nova Scotian waters, and around Prince Edward Island (Bigelow and Schroeder, 1953). Based on observer reports, a movement from deeper waters onto the banks of the Scotian Shelf (Div. 4VsW) has been observed to occur after the second quarter of the year (Simon and Frank, 1996).
The area occupied by winter skate can be estimated from research vessel survey data. In the southern Gulf, stratified mean percent occurrence data indicate a highly fluctuating trend in area occupied since 1971 (Simon et al., 2003). There is some evidence to suggest that area occupied was somewhat larger in the late 1970s and 1980s than it is at present. Based on surveys conducted throughout the Bay of Fundy and both western and eastern portions of the Scotian Shelf, area occupied shows no discernible trend since the early 1970s (Simon et al., 2003). By contrast, when data are restricted to the eastern Scotian Shelf only (4VW Cod March RV Survey), area occupied at present appears to be approximately half that of the mid-1980s. Distribution indices for Georges Bank winter skate show no discernible trend since the mid-1980s (Simon et al., 2003).
Winter skate have not been assessed previously by COSEWIC, the IUCN, or under the auspices of any other convention on species protection. Winter skate are the target of a directed fishery in New England in the United States and on the eastern Scotian Shelf in Canada. They are also caught as bycatch in other fisheries for groundfish and in fisheries for shellfish. The small directed fishery in Canadian waters is regulated by catch quotas.
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