Occurrences of Jellyfish in the Industrial Fishing Activity of the Southeastern and Southern Regions of Brazil

Abstract

AbstractThis work presents the results of a survey of the occurrences of jellyfish bycatch in trawling, bottom gill‐net, purse seine, and pole‐and‐line fishing gear in the main fishing port of southern Brazil Survey results are based on interviews conducted with fishers at the time of landing the catch. Historical data were also obtained on the peak occurrences of jellyfish in the last 20 years through interviews with fishers that had worked for up to 50 years in the area. Jellyfish were found to occur with the different fishing gear and to have preferential demersal behavior. The highest frequencies of occurrences were observed on the continental shelf and accompanied the trips of the fishing fleet at different times of the year. Hydrozoan jellyfish, presumably Rhacostoma atlanticum and Olindias sambaquiensis, were the most frequent and abundant species recorded during the period, but the historical data suggest peaks of occurrence every 10 years when dominant groups are replaced with others. The hypotheses of the change of diversity in the 10‐year period from 1993 to 2013 can be attributed to natural processes associated with ecological strategies used by gelatinous organisms or the occupation of niches that become available with the withdrawal of planktivorous fish species in the context of overfishing.