Research Document 1997/54

Assessment of haddock on eastern Georges Bank

By S. Gavaris and L. van Eeckhaute

Abstract

Haddock catches from eastern Georges Bank fluctuated around 5,000 t from early 1980s to 1993. Under restrictive management measures, catches declined to a low of 1,1000 t in 1995 and increased to 3,700 t in 1996. The 1991, 1992, and 1993 year-classes comprised about 87% of the 1996 fishery catch by weight. An increasing trend in survey adult abundance was observed from 1992 to 1996. Survey indices indicate that the 1992 year-class was the strongest since the 1983, 1985, and 1987 year-classes but abundance of the 1994-96 year-classes is low.

The adaptive framework was used to calibrate the sequential population analysis to the research survey trends. Since 1993, the biomass has steadily increased to about 24,000 t in 1996 and declined slightly to 23,000 t in 1997. The recent increase was enhanced by increased survivorship of young haddock from reduced capture of small fish in the fisheries. The abundance of the 1992 year-class was estimated at about 15 million, comparable to the 1983, 1985, and 1987 year-classes. The 1991 and 1993 year classes were estimated at about 7 and 10 million respectively, while the incoming 1994, 1995, and 1996 year-classes appear relatively weak at about 5 million. The exploitation rate declined in 1994 and again in 1995 reaching a level below the F_0.1 target where it remained for 1996.

Combined Canada/U.S.A. projected yield at F_0.1 = 0.28 in 1997 would be about 6,300 t. If fished at F_0.1 in 1997, the biomass for ages 3 and older is projected to decrease slightly from 20,500 t to about 19,250 t at the beginning of 1998. The 1992 year-class would comprise about one-quarter of age 3+ biomass and almost half the forecast yield. A risk analysis showed that a combined Canada/U.S.A. yield of 4,000 t in 1997, about what was caught in 1996, decreases the chance that the F_0.1 is exceeded to less that 10% and increases the chances that the biomass for ages 3 and older will increase between 1997 and 1998 to about 70%.

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