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Research Document - 2009/061

Assessment of the cod (Gadus morhua) stock in NAFO Divisions 2J+3KL in 2009

By J. Brattey, N.G. Cadigan, K. Dwyer, B.P. Healey, M.J. Morgan, E.F. Murphy,
D. Maddock Parsons and D. Power

Abstract

The status of the northern cod (Gadus morhua) stock in NAFO Div. 2J+3KL was assessed at a Zonal meeting held in St. John’s, NL during 24 February–6 March 2009. A directed “stewardship” cod fishery and a recreational fishery were re-opened in the inshore during 2006 and continued in 2007 and 2008; the offshore remained closed to directed fishing in both years. There was no formal TAC, but commercial fishers were permitted an allowance of 3,000 lb of cod per license holder in 2006, 2,500 lb in 2007, and 3,300 lb in 2008. Recreational fishers were permitted 5 fish per person per day, up to a maximum of 15 fish per boat. Reported total landings from all fisheries in 2008 (stewardship, recreational, sentinel, and by-catch) were 4,162 t. The reported landings are comprised of 3,089 t in the stewardship fishery, which includes 121 t of by-catch, and 818 t in the recreational fishery; an additional 254 t were landed in the sentinel surveys.

Offshore abundance and biomass indices from the autumn DFO research vessel (RV) survey increased further in 2008 and have shown an increasing trend since 2003 at an average annual rate of 30% for abundance and 60% for biomass. Most of the increase is taking place in southern 3K and northern 3L in a region that encompasses only 14% of the total surveyed offshore area. The average index values during the past three years (2006-08) compared to the average of the 1980’s have increased to ~8% for abundance, biomass, and spawning stock biomass (SSB). The recent decline in total mortality rate (Z) has persisted and the average annual value for Z in 2007-08 is 0.24 in spite of the resumption of the commercial and recreational fisheries in the inshore; this suggests that the rate of natural mortality (M) has declined substantially and the prospects for stock recovery have improved. Year-class strength in the offshore remains poor compared to the 1980s and most of the improvement in stock status seen in recent years is due to growth and improved survival rates, particularly for the 2000-02 year-classes. A second winter (March 2008) acoustic survey of the traditional over-wintering area along the continental shelf edge encountered a large aggregation (estimated at ~100,000 t total biomass and ~42,000 t SSB) of cod in southern 3K, but cod densities were generally low elsewhere. Offshore tagging and telemetry indicated that a substantial portion of cod from the offshore 3K aggregation migrated to the inshore of 3KL; exploitation of these offshore cod in the inshore (based on tagging) was 6%. This new evidence of inshore migration indicates that the moratorium in the offshore is no longer sufficient to protect the offshore stock until recovery is well established.

In the inshore, sentinel survey gillnet catch rates in the northern area are low but are currently above the average of the time series (1995-2008). In the central area, gillnet and line trawl catch rates have improved consistently since 2003, are above average, and are at a higher level than other inshore areas. In the southern area, catch rates with gillnets have remained stable since 2005, but are marginally below average. Mean exploitation rates (percent harvested) from tagging studies ranged from 3-7% among inshore central and southern areas. Recruitment information, from sentinel small-mesh gillnet and beach seine studies, suggests that the 2003 and 2004 year-classes are weaker than those produced during 2000-02.

Although specific limit reference points for this stock have not been established, overall the stock is well below any reasonable limit reference point and remains in the critical zone with respect to the precautionary approach (PA). Application of the PA would require that any catch in 2009 be at the lowest possible level. This would include no directed fishing and measures to reduce cod by-catch in other fisheries. Status offshore is improving, but the stock has not increased across much of the historical geographic range and management should focus on promoting further increases in SSB and improved recruitment until the stock is more resilient to the effects of fishing. Recent fisheries have resulted in low exploitation rates and permitted growth in SSB in some offshore areas; if fishing is conducted in 2009, exploitation rates should not be allowed to increase. Recruitment information suggests that inshore exploitable biomass in 2009-10 is likely to be similar to 2008-09; therefore, to achieve the same exploitation rates as in 2008 total removals (recreational plus commercial) should not be allowed to increase.  In addition, catch rates in the inshore northern area, are lower than in other inshore areas suggesting lower cod abundance. Fisheries in the northern area depend on seasonal immigration of fish, possibly from offshore regions, including offshore 2J where biomass remains low. Therefore, it would be prudent to minimize removals from this area. In the inshore southern area, catches are partly dependant on seasonal immigration of cod from 3Ps where the stock is declining; future removals may therefore rely more heavily on cod from the offshore of 3KL.

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