Research Document - 2005/081

Assessment of White Hake (Urophycis tenuis) in NAFO Divisions 4VWX and 5

By Bundy, A. and J. Simon

Abstract

White hake (Urophycis tenuis) are bottom dwelling fish whose distribution ranges from the southern Grand Banks to the mid-Atlantic Bight. Their depth range varies with life history stage, with age 2 and older fish occurring predominantly at depths between 50 to 400 m. They favour temperatures between 6 ºC and 10 ºC. The stock structure in NAFO Divisions 4VWX/5 may be complex, with several self-sustaining components. White hake in the Laurentian Channel slope waters (NAFO Sub-division 4Vn) are contiguous with NAFO Division 4T. Those in the Bay of Fundy and approaches are contiguous with NAFO Divisions 5Z and 5Y (i.e. the Gulf of Maine area). The central Scotian Shelf (parts of NAFO Divisions 4X and 4W) may be separate from those to the east and west. The present management units (NAFO Divisions 4T, 4VWX+5Zc, and USA 5+6) in the NW Atlantic, do not reflect clear discontinuities in adult distributions. On the Scotian Shelf white hake is assessed as three components, NAFO Divisions 4Vn, 4VsW and 4X/5. About 90 % of the white hake landed in NAFO Divisions 4VWX and 5Zc are currently from 4X and 5Zc.

The landings from all areas of NAFO Divisions 4VWX/5 have declined in recent years and total landings have declined since 1987. Canadian fishing effort for this species was unregulated in NAFO Divisions 4VWX/5 until 1996 when it was placed under quote regulations. Since 1999, the white hake fishery has been a by-catch fishery only. White hake are caught in longline, gillnet and otter trawl fisheries targeting halibut, redfish, cod, pollock and other groundfish. This has management implications in an ecosystem context. Several indicators were used to assess the health of white hake population: there are very few large white hake on the Scotian Shelf (NAFO Divisions 4VW) now compared to the 1980s, despite reduced catches in all areas and indications of good recruitment; in NAFO Divisions 4X/5, there has been a variable but general decrease in the abundance of white hake since the early 1990s; fishing mortality is relatively low in all areas since the introduction of catch limits; total mortality on the Scotian Shelf is high and its causes are unknown, whereas total mortality of white hake in the Bay of Fundy is variable. Overall, the status of white hake in NAFO Sub-division 4Vn and NAFO Division 4VsW is poor and requires rebuilding. In NAFO Divisions 4X/5, unless there is good recruitment over the next few years, catches at the current level may lead to further decreases in abundance.

Complete document (PDF, 592 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.