Flutuações populacionais de Sterna dougallii Montagu, 1813 (Aves: Charadriiformes) por meio do olhar de pescadores artesanais de Paracuru (Estado do Ceará)

Abstract

Brazil is the second country with the highest number of bird species in the world, however, it is also the second with the largest number of globally threatened bird species. In this context, migratory birds (10% of Brazilian species) are especially vulnerable as they depend on different habitats along their migratory routes to complete their life cycles. Among them, the North American population of Sterna dougallii (Laridae), roseate terns, is currently endangered in North America and Brazil, due to combined threats, such as hunting, prey population decline and habitat degradation. Roseate terns winter along the north and east Brazilian coast and, for global conservation to be effective, it is necessary to better understand the ecology in this wintering habitat. It is necessary to find complementary diagnostic tools to mitigate the scarcity of data. Using the Local Ecological Knowledge (LEC) of artisanal fishermen is a promising method, because these men perceive fluctuations in biomass, abundance and richness of fish assemblages, which can make up a relevant part of S. dougallii’s diet. On the other hand, the roseate turn is also a target of interactions with fishermen, being very sensitive to changes in prey patterns and habitats, therefore a relevant bioindicator of fishing resources availability. The ecological and socioeconomic relevance of this bird is clear, since so many communities rely on fishing as the basis for their livelihood and income. The present study aimed to assess, through reports of artisanal fishermen in the city of Paracuru (State of Ceará), changes in the population dynamics of S. dougallii, to map its habitats and record its diet. With support from the Associação de Pesquisa e Preservação de Ecossistemas Aquáticos (Aquasis) and the Projeto Aves Migratórias do Nordeste, forms were applied in semi-structured interviews, in June 2021, with 22 respondents. Data was categorized and the results were analyzed using descriptive statistics. Only five respondents noted population decline of S. dougallii in the 1980s, in contrast to 60% of respondents, who noted no fluctuation in the population. However, fishermen recognize a wide variety of foraging and roosting habitats for birds of the Laridae family. From their reports, it was possible to identify two probable prey items of S. dougallii: Anchoa hepsetus and Anchoa tricolor, locally known as “manjubinhas”. An intense conflict was reported between local artisanal fishermen and the practice of industrial fishing. This may have negative repercussions for the future of artisanal fishing in the municipality and for seabirds such as S. dougallii, due to the overexploitation of marine resources. In contrast, the relationship between artisanal fishermen and birds of the Laridae family was completely positive. No record of historical pressure on these animals was reported. Thus, it is expected that future collaborations in activities for the conservation of coastal and marine birds in the municipality will be well accepted by fishermen.