Preliminary assessment of the jellyfish bycatch captured off southern and southeastern Brazil
Rafael Schroeder | Joaquim O Branco | Felipe Freitas | Charrid Resgalla
Macromedusoid forms of Hydrozoa, Scyphozoa and Cubozoa captured by different fishing gears active in south and southeast of Brazil were recorded on board by scientific observers. After each fishing operation, catch composition was quantified and precise information about the position of the catch was taken between 2008 and 2011. Macromedusae records have been systemized in order to analyze the spatial-temporal distribution, the areas of concentration of the identified species and their relationship with other components of the bycatch. Catch composition analyzed in 986 fishing tows, demonstrated that the participation of these organisms ranged from 6-16%, and the hydromedusae Rhacostoma atlanticum L. Agassiz, 1851 and Olindias sambaquiensis Müller, 1861 were the most abundant and widely distributed species. R. atlanticum was recorded between 20 and 140 m deep while O. sambaquiensis presented registers in shallower waters between 10 and 70 m. No other identified species has been recorded in depths greater than 60 m. Areas of high concentration included the north-central coast of Santa Catarina and Paraná, the northern part of São Paulo and the north-central portion of Rio Grande do Sul State. Although the participation of the macromedusae has been relatively low, in areas of elevated concentration, the relative importance was high, making its participation almost exclusive among other zoological groups. Those registers of abundance and the respective areas of high concentration of macromedusae, which were associated to high primary production sites, may serve as a theoretical reference of the abundance of these organisms for future studies that aim to evaluate possible changes in jellyfish populations.
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