Bruno L. Mourato

Spatio-temporal distribution and target species in a longline fishery off the southeastern coast of Brazil

In the present study, a cluster analysis, in relation to the species composition of the catches, was used to classify 6,486 fishing sets by a longline fleet based in Sao Paulo State, Brazil, from 1998 to 2006. Based on the proportions of 12 species and three broader species groups, three clusters were identified: C1: other fishes; C2: blue shark; C3: swordfish. Results indicated that the fleet targeted mainly blue shark and swordfish and also showed that the blue shark importance in this fishery has been growing progressively trough the years. Offshore areas were exploited mainly in the first and fourth quarters (from 2001 mainly), while the fishing effort was more concentrated near the continental shelf break, during the second and third quarters (for the whole period). The longline fishery based in Sao Paulo State changed fishing strategy to target different species which produced important changes in catch-per-unit-effort (CPUE) of the main species caught. Cluster analysis seems to have appropriately identified these changes over time, which is an important information, often missing in logbooks.

Reproductive biology and space–time modelling of spawning for sailfish Istiophorus platypterus in the western Atlantic Ocean

ABSTRACT This study presents data and estimates reproductive parameters of the sailfish Istiophorus platypterus (Shaw, 1792) in the western Atlantic, useful for future stock assessments of the species in the Atlantic Ocean. During the period 2006–2011, a total of 1132 fish were sampled by scientific observers on board Venezuelan and Brazilian longline vessels and from artisanal fisheries based out of Cumaná, Puerto La Cruz and Playa Verde, Venezuela and Cabo Frio, Rio de Janeiro, Brazil. The ovaries of 543 females were classified into five ovarian development phases based on microscopic analysis of the most advanced group of oocytes. Generalized additive models were applied to the gonadal index and sex ratio data in order to assess spatio-temporal trends of the reproductive activity and identify the spawning areas. Space–time effect was a significant factor contributing to changes in sex ratio and reproductive activity. Spawning activity was observed in two distinct areas. On the south-east Brazilian coast spawning peaked during December–February, while in the south-eastern Caribbean Sea spawning occurred between March and September, with its peak in March and April. Using a Bayesian approach, size at 50% maturity was estimated to be 146.12 cm (credibility interval of 95%, 138.45–152.09 cm). Batch fecundity ranged from 436,800 to 2,492,500 hydrated oocytes per female. This study confirms multiple aggregation spawning for this species in the western Atlantic Ocean.