Growth, mortality, recruitment, and yield of the jumbo squid(Dosidicus gigas) off Guaymas, Mexico

摘要

This paper reports on the population dynamics of Dosidicus gigas from the Gulf of California over the period of the 1995-1996 to 2001-2002 fishing seasons. Data were collected on mantle length, individual weight, and total catch. The D. gigas catches varied, with the lowest landings (1970 t) in the 1997-1998 fishing season and the highest (41,330 t) in 2001-2002. Mantle length ranged from 16 to 96 cm. The mantle length-mass relationship for all seasons showed allometric growth. Growth and natural mortality of D. gigas varied between seasons. The analysis of cohorts showed high interannual variability in annual fishing mortality, annual exploitation rate, recruitment, and mean abundance. The Thompson-Bell predictive model indicated that in some seasons the maximum sustainable yield could have been obtained with 30-50% of the current fishing mortality. However for other seasons the maximum sustainable yield could have been obtained with a current or greater fishing mortality. The fishing mortality associated with the maximum sustainable yield, F sub(MSY), did not necessarily coincide with the fishing mortality associated with a level of proportional escape of spawning biomass, F sub(%BR). The variability observed in this study is typical of squid populations but impossible to anticipate using the Thompson-Bell model. Consequently, auxiliary information (i.e. from research cruises) reflecting such variability in recruitment is needed to make accurate predictions and efficiently manage these resources. Extreme care should be taken in using these methods alone to predict future yields of D. gigas.