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Estudo das Capturas Acidentais e Interações de Aves Marinhas em Redes de Emalhar e de Cerco e Avaliação de Medidas de Mitigação na Zona de Proteção Especial Aveiro-Nazaré
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Resumo(s)
Neste estudo foram caracterizadas as capturas acidentais e as interações de aves marinhas em redes
de cerco e de emalhar (1 pano e tresmalho) na Zona de Proteção Especial Aveiro-Nazaré, em 2021-2024,
através de observações a bordo, diários de pesca e inquéritos a pescadores. Adicionalmente, foi avaliada
a eficácia do papagaio afugentador e da gestão controlada das rejeições como potenciais medidas de
mitigação à captura acidental de aves marinhas, através de observações a bordo. Considerando os 305
eventos monitorizados por observadores a bordo, foram registadas 39 capturas de 7 espécies de aves. O
tresmalho foi a arte que afetou o maior número de aves. O alcatraz, a gaivota-de-patas-amarelas/gaivotad’asa-escura e a pardela-balear foram as espécies mais afetadas. Tais resultados foram reforçados pela
informação recolhida através dos diários de pesca e inquéritos. As interações das gaivotas no cerco
mostraram diminuir significativamente com o aumento da distância à linha de costa e durante o período
reprodutivo. No tresmalho, as interações aumentaram com a duração dos eventos e a quantidade de
rejeições libertadas. Já as interações dos alcatrazes em redes de tresmalho aumentaram com a duração e
a quantidade de aves de outras espécies interagindo, e diminuíram durante a época migratória e
reprodutora. Tanto as interações das gaivotas, como as do alcatraz, mostraram uma relação não-linear
com a distância à linha de costa dos eventos de tresmalho. Não foi possível adquirir resultados para as
interações da pardela-balear em nenhuma das artes. Nenhuma das medidas de mitigação mostrou um
efeito significativo na redução das capturas acidentais, possivelmente devido a uma amostragem
insuficiente. Apesar das limitações amostrais e dos resultados potencialmente subestimados, este estudo
comprovou a existência de uma realidade preocupante na ZPE Aveiro-Nazaré, com potencial para ser
uma das áreas com a taxa de captura acidental de aves marinhas mais elevada do país.
In this study, bycatch and interactions of seabirds in purse seine and gill nets (simple and trammel nets) in the Aveiro-Nazaré SPA, in 2021-2024, were characterized, through onboard observations, logbooks and surveys of fishermen. Additionally, the effectiveness of a bird scaring device and discard control as potential mitigation measures for the bycatch of seabirds was evaluated, through onboard observations. Considering the 305 events monitored by observers on board, 39 captures of 7 seabird species were recorded. Trammel net was the fishing gear that affected the largest number of seabirds. The northern gannet, the yellow-legged gull/lesser black-backed gull and the balearic shearwater were the most affected species. These results were reinforced by information collected through logbooks and surveys. Seagull interactions in purse seine nets have been shown to decrease significantly with increasing distance from the shoreline and during the breeding period. In the trammel nets, interactions increased with the duration of the events and the amount of discard released. The interactions of northern gannets in trammel nets increased with the duration and number of birds of other species interacting and decreased during the migratory and breeding season. Both seagull and northern gannet interactions showed a non-linear relationship with the distance from the coastline of trammel events. It was not possible to acquire results for balearic shearwater interactions in any fishing gear. None of the mitigation measures showed a significant effect on reducing bycatch, possibly due to insufficient sampling. Despite sample limitations and potentially underestimated results, this study proved the existence of an alarming reality in the Aveiro-Nazaré SPA, with the potential to be one of the areas with the highest rate of seabird bycatch in the country.
In this study, bycatch and interactions of seabirds in purse seine and gill nets (simple and trammel nets) in the Aveiro-Nazaré SPA, in 2021-2024, were characterized, through onboard observations, logbooks and surveys of fishermen. Additionally, the effectiveness of a bird scaring device and discard control as potential mitigation measures for the bycatch of seabirds was evaluated, through onboard observations. Considering the 305 events monitored by observers on board, 39 captures of 7 seabird species were recorded. Trammel net was the fishing gear that affected the largest number of seabirds. The northern gannet, the yellow-legged gull/lesser black-backed gull and the balearic shearwater were the most affected species. These results were reinforced by information collected through logbooks and surveys. Seagull interactions in purse seine nets have been shown to decrease significantly with increasing distance from the shoreline and during the breeding period. In the trammel nets, interactions increased with the duration of the events and the amount of discard released. The interactions of northern gannets in trammel nets increased with the duration and number of birds of other species interacting and decreased during the migratory and breeding season. Both seagull and northern gannet interactions showed a non-linear relationship with the distance from the coastline of trammel events. It was not possible to acquire results for balearic shearwater interactions in any fishing gear. None of the mitigation measures showed a significant effect on reducing bycatch, possibly due to insufficient sampling. Despite sample limitations and potentially underestimated results, this study proved the existence of an alarming reality in the Aveiro-Nazaré SPA, with the potential to be one of the areas with the highest rate of seabird bycatch in the country.
Descrição
Relatório de estágio de mestrado, Ecologia e Gestão Ambiental, 2024, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Portugal tresmalho monitorização papagaio-afugentador gestão de rejeições Relatórios de estágio de mestrado - 2024