Research Document - 2002/072

Population Status of Eastern Georges Bank Cod (Unit Areas 5Zj,m) for 1978-2002

By J.J. Hunt and B. Hatt

Abstract

An analytical assessment of the Georges Bank cod stock in 5Zj,m was completed using updated catch-at-age for ages 1-10 and research survey indices. A revised ADAPT formulation, based on TRAC recommendations involving a reduced number of RV indices and direct estimates for 1997-2000 Foldest , was used to characterize the population. Results of the assessment provided statistically significant parameter estimates for the 2002 beginning-of-year population at ages 2 through 10. Bias and precision for the estimates were within acceptable limits. The adult biomass increased from the low of 8,900t in 1995 to about 21,100t at the beginning of 2001, primarily due to survival and growth of the 1992, 1995 and 1996 year-classes. Since 2001, adult biomass has declined and was about 17,300t at the beginning of 2002. Exploitation rate on ages 4-6 decreased from more than 50% in the mid-1990's to below the F0.1 reference level in 1999-2000 but increased to 20% in 2001. A change in partial recruitment to the fishery has occurred since 1994 with reduced catchability on ages 5+. This change is due to the bycatch nature of the fishery and to management measures that reduced spatial and temporal access to the resource. Recruitment in recent years has been poor, with the 1992, 1995 and 1996 year-classes being moderately stronger than adjacent year-classes. The 1998 year-class appears to be above the recent average. Projections for 2002 indicate a yield of about 1,900 t at F0.1 and the stock biomass will remain stable between 2002 and 2003. Only at 2002 yields of 1,000 t or less is there a 50% or better chance of a 10% increase in biomass. The adult stock biomass remains below a threshold of 25,000 t, above which chances of good recruitment are improved.

With the current poor recruitment and exploitation rates near the present levels, improvement in stock status is not expected in the near term.

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