Atlantic Fisheries Research Document 1996/028

Evaluation of the stock status of 4WX herring

By R.L. Stephenson; M.J. Power; D.G. Melvin; S. Gavaris

Abstract

The 1994/95 TAC for 4WX herring was reduced to 80,000t due to a number of indications of reduced stock status observed from the 1994 fishery and reduced larval herring abundance in the 1994 survey. Management of this fishery moved further toward a spawning stock unit approach, with in-season consideration of individual spawning components and discrete fisheries. Landings in the stock portion of the 1995 4WX herring fishery declined to 62,500t, the lowest on record since 1964. An additional 18,250t was recorded from the non-stock weir and shutoff fisheries on the New Brunswick side of the Bay of Fundy. The purse seine fleet dominated landings with catches of 58,900t.

A very large portion of the stock catch was made up of fish of ages 2 - 4 (79% in number, 59% in weight). Age 3 fish (1992 year-class; approximately 25 cm length) dominated landings from the stock portion of the fishery in both number (39%) and weight (27%). Although this high proportion of small fish has been observed before, primarily during the meal fishery in the 1960s, the reduced proportion of older fish in the catch is cause for concern. Catch at age shows that while the weight of fish landed from the stock portion was less in the 1995 fishery than in 1994, the same number of fish were caught (i.e. more fish of smaller weight).

Stock status evaluation was based on sampling and analysis of the commercial fishery and the results of a larval abundance survey. The annual survey of herring larvae showed a dramatic drop in 1994 and only a moderate increase in 1995. There have been no strong year-classes since 1983 and there continues to be concern for the state of this stock. The spawning stock biomass has decreased considerably in recent years, and while it is estimated to have increased slightly in the last year, it is still estimated to be between 100,000 and 200,000t. Projections from an intermediate level within this range (terminal F=0.3) would indicate an F_0.1 yield in 1996 of about 50,000t. It is noted that a large portion of the projected biomass and yield are from recruiting year-classes. The catch in 1996 is predicted to contain 42% by number and 18% by weight, fish 3 years of age.

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