Based on biological and meteorological long-term database (1979-1983 and 1996-2000), we analyzed the variation in the juvenile recruitment and artisanal fishery landings of the mullet (Mugil platanus) in the Patos Lagoon estuary and its relationships with the regional rainfall and estuarine salinity anomalies during two strong El Niño events (1982-83 and 1997-98). Juvenile and adult mullets declined in abundance under the high rainfall and near-zero salinity that prevailed in the estuary during both El Niño events. We proposed two different hypotheses to explain the El Niño-induced effects on the juvenile and adult stages of the mullet in the estuary. First, high freshwater outflow during a very strong El Niño might render ineffective the mechanism of passive immigration of juvenile mullets into the estuary, which can lead to their decline in the estuary during El Niño events. Second, near-zero salinity at the estuarine area along several months during strong El Niño events could lead to higher spatial dispersion of the maturing mullet during their migration to the ocean , resulting in smaller shoals of individuals and, consequently, lower catches by artisanal fishermen.
Biota of the Patos Lagoon estuary and adjacent marine coast: long-term changes induced by natural and human-related factors
