Temperature conditions in the Argentine chub mackerel (Scomber japonicus) fishing ground: implications for fishery management

We describe the seasonal migrations of Argentine chub mackerel (Scomber jap onicus) into the fishing ground in relation to sea surface temperature cond itions and analyse the temperature evolution during the fishing season on t he basis of 1955-97 time-series. The upper temperature limit for the presen ce of schools was around 19 degreesC. At higher values, most schools leave coastal waters (<50 m) for the shelf An inverse relationship was observed b etween catches per unit of effort (CPUE) of the inshore fishery and sea sur face temperature. The highest standardized CPUE values corresponded to temp eratures lower than 19<degrees>C. Above this temperature, the probability o f obtaining a standardized CPUE higher than I was extremely low, and the st andard deviations were minimal. The economic benefit from catches was also analysed through the different months of the fishing season. It was found t hat the mean benefit corresponding to temperatures lower than 19 degreesC e xceeded approximately 15 times that obtained at higher temperatures. A simp le fishing strategy was proposed to the commercial fleet in order to improv e the economic benefit of the catches. The migratory pattern followed by ma ckerel during the spawning period was also ana, lysed in relationship to ot her environmental factors like food availability. Zooplankton composition, size structure and abundance in coastal and shelf waters are described, and their implications for feeding ecology of larvae and adults of the species are discussed.