ABSTRACT Seasonal ecological effects caused by temperature and photoperiod are typically considered minimal in the tropics. Nevertheless, annual climate cycles may still influence the distribution and abundance of tropical species. Here, we investigate whether seasonal patterns of precipitation and wind speed influence the structure of coastal fish assemblages and fishing yields in northeast Brazil. Research trips were conducted during the rainy and dry seasons using commercial boats and gear to sample the fish community. Diversity was analyzed using abundance Whittaker curves, diversity profiles and the Shannon index. Principal Component Analysis (PCA) was used to analyze associations between the abundance of species and various environmental variables related to seasonality. A total of 2,373 fish were collected, representing 73 species from 34 families - 20 of which were classified as both frequent and abundant. Species richness was greater and more equitable during the rainy season than the dry season - driven by changes in the precipitation rather than to wind speed. Species diversity profiles were slightly greater during the rainy season than the dry season, but this difference was not statistically significant. Using PCA was identified three groups of species: the first associated with wind speed, the second with precipitation, and the third with a wide range of sampling environments. This latter group was the largest and most ecologically heterogeneous. We conclude that tropical coastal fish assemblages are largely influenced by local variables, and seasonally mediated by annual changes related to precipitation intensity and wind speed, which in turn influences fishery yields.

Geographical variation in biophysical conditions may strongly influence the life history characteristics of widely distributed species, such as the Brazilian sharpnose shark, Rhizoprionodon lalandii (Müller & Henle, 1839). Here, we use original and secondary data of reproductive traits of R. lalandii to identify population differences among northern/northeastern and southern Atlantic waters of South America. In the southeast region, birth occurs between December and March, and the young become frequent along the coast between April and September. Mating occurs mainly between March and June, when females with bite marks are common. Females in early pregnancy occur between March and September. The reproductive cycle of R. lalandii in the northern/northeastern region was approximately six months ahead of the cycle described for the southeastern region. These results support the hypothesis that environmental conditions in the North-Northeast and Southeast generate differences in life history traits, resulting in at least two distinct populations along the Brazilian coast.

Este trabalho é resultado de uma oficina realizada em 2006 em Tamandaré, PE, a qual teve por objetivo discutir elementos para a construção de um programa nacional em gestão compartilhada do uso de recursos pesqueiros no Brasil, constituído por vários projetos de pesquisa-ação com potencial de contribuir para a incorporação da gestão compartilhada em políticas públicas. Os 30 pesquisadores presentes identificaram: (i) fatores impulsionadores/oportunidades e (ii) limitações/dificuldades enfrentadas na gestão compartilhada, e (iii) Linhas de pesquisa e ações para subsidiar a construção de tal programa.

This paper is an output of a workshop carried out in 2006, in Tamandaré, PE, aiming to discuss elements for the construction of a national program of fisheries co-management in Brazil. This program should be constituted by many participatory action-research projects with the potential to contribute for the incorporation of the co-management concept in public policies. The workshop involved 30 researchers who identified: (i) opportunities/driving factors and (ii) limitations/problems faced for fisheries co-management in Brazil, and (iii) research lines and actions needed to subsidize the construction of such program.