Research Document - 2002/057

Stock assessment of Georges Bank yellowtail flounder for 2002

By H.H. Stone

Abstract

The combined Canada/USA yellowtail flounder (Limanda ferruginea) catch has been increasing since 1995, and in 2001 was 6,790 t. While fishermen reported lower catch rates in 2001 compared with 2000, recent groundfish survey trends in abundance indicate that the stock is still at a relatively high level compared to the early 1990s. Population biomass (age 1+) has increased 12 fold since 1995, and is at the highest observed level since 1973. The age structure is improving but older fish are still under-represented. Recent recruitment has improved relative to the 1980s, and the 1997 year-class appears to be the strongest since 1980. The 1998 and 2000 year-classes appear to be of moderate strength although the latter is not well estimated. Exploitation rates on ages 4+ have been less than F_0.1 (20%) in 2000 and 2001, while exploitation at age 3 has not decreased since 1997. At the F_0.1 yield of 10,300 t, which corresponds to about 45% probability of exceeding F0.1, the biomass is not likely to decrease and there is a 75% probability of achieving 10% increase from the beginning of the year 2002 to 2003. The dominant 1997 and 1998 year-classes are expected to contribute about 50% of the expected yield as ages 4 and 5 in 2002, and comprise about 39% of the total biomass. The 2000 year-class is estimated to contribute 26% of total beginning of year biomass in 2003, however, this yearclass is not well estimated and was based on only a single survey index value in this year's assessment.

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