Atlantic Fisheries Research Document 1996/070

Status of American plaice in NAFO Division 4T, 1995

By R. Morin; G. Chouinard; I. Forest-Gallant; T. Hurlbut; G. Neilsen; A. Sinclair; D. Swain

Abstract

Provisional landings of American plaice in NAFO Division 4T totalled 2,311 t in 1995, considerably lower than the average of 7.647 t since 1960. Landings reached their lowest level in 1993 (1,403 t), the year that the Atlantic cod fishery was closed in 4T. The increase in landings since 1993 was attributed to fewer closures in the commercial fishery and increased effort by mobile gear. The annual total allowable catch (TAC) of 4T plaice was maintained at 10,000 t from 1977 to 1992; since 1993, it has been set at 5,000 t. All fleet sectors reported landings below their allocated quotas in 1995, with the exception of the competitive mobile fleet of vessels less than 45 feet. Seines contributed about 75% of the landed catch (1,731 t in 1995). Commercial plaice catches have increasingly concentrated in the eastern part of 4T since 1993, in unit areas 4Tf and 4Tg. The 1995 research survey of 4T resulted in an average catch of 176 plaice per tow, the lowest catch rate on record for this survey. Since 1971, plaice catches have averaged 395 per tow with the highest average catch in 1977 (1,127 per tow). Survey data indicate that the stock declined in abundance in the late 1970s and has fluctuated at a low level since 1982. Multiplicative analyses of mean catch-at-age data from research data indicated that total mortality from 1994 to 1995, between ages 5 and 13 years, standardized for year-class abundance, was approximately 0.36 for both males and females. Similar analyses indicate that year-classes of the early 1970s were abundant, but have been relatively weak in abundance over the past 20 years. A length-based index of fishing mortality (F), calculated from the ratio of commercial to research catches, indicated an increasing trend in F from the mid-1980s to 1993. Predicting the abundance of research catch-at-age for 1996, commercial removals in the order of 1,000 t would be required for 1996 to lower F to levels recorded during the 1970s.

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