Observations of Length at Maturity in Yellowtail Flounder on the Grand Bank (1995-97)

Abstract

Length and age at maturity are essential information to determine the spawning stock biomass and stock-recruit relationship. The usual knife-edge estimates of the mature proportions in fish populations obscure the knowledge on the true levels of the spawning potential of the stocks and the temporal variability is ignored. The yellowtail flounder stock is mainly concentrated on the southern Grand Bank, where the juvenile and the adult components overlap in their distribution. There was a fishing moratoria for this stock from 1994 to 1997, and for 1998 the Scientific Council recommended reopening a limited fishery, stating also that this fishery should be carefully monitored and sampled. Morgan and Walsh (1977) presented estimates of length and age at maturity for yellowtail flounder in Divisions 3 LNO from 1975 to 1995, based on the Canadian spring survey. In this paper additional information on this subject is presented, based on the results of the of the Spanish spring survey in Divisions 3NO.