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Understanding temporal patterns of marine mammal occurrence is useful for establishing conservation strategies. We used a 38 yr-long dataset spanning 1976 to 2013 to describe temporal patterns and trends in marine mammal strandings along a subtropical stretch of the east coast of South America. This region is influenced by a transitional zone between tropical and temperate waters and is considered an important fishing ground off Brazil. Generalized Additive Models were used to evaluate the temporal stranding patterns of the most frequently stranded species. Forty species were documented in 12,540 stranding events. Franciscana (n = 4,574), South American fur seal, (n = 3,419), South American sea lion (n = 2,049), bottlenose dolphins (n = 293) and subantarctic fur seal (n = 219) were the most frequently stranded marine mammals. The seasonality of strandings of franciscana and bottlenose dolphin coincided with periods of higher fishing effort and strandings of South American and subantarctic fur seals with post-reproductive dispersal. For South American sea lion the seasonality of strandings is associated with both fishing effort and post-reproductive dispersal. Some clear seasonal patterns were associated with occurrence of cold- (e.g. subantarctic fur seal) and warm-water (e.g. rough-toothed dolphin) species in winter and summer, respectively. Inter-annual increases in stranding rate were observed for franciscana and South American fur seal and these are likely related to increased fishing effort and population growth, respectively. For subantarctic fur seal the stranding rate showed a slight decline while for bottlenose dolphin it remained steady. No significant year to year variation in stranding rate was observed for South American sea lion. The slight decrease in frequency of temperate/polar marine mammals and the increased occurrence of subtropical/tropical species since the late 1990s might be associated with environmental changes linked to climate change. This long-term study indicates that temporal stranding patterns of marine mammals might be explained by either fishing-related or environmental factors.

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Franciscana dolphin Pontoporia blainvillei bycatch has been high for near six decades in western South Atlantic, with large regional variation. In 2012, the Brazilian Government‐regulated gillnet fisheries in south and southeast Brazil by reducing fishing effort and establishing no‐fishing zones. However, there is evidence that the magnitude of franciscana bycatch remains high and unsustainable. The aims of this study were to identify hotspot areas of franciscana bycatch associated with two main gillnet fisheries and to propose no‐fishing zones combined with limited total allowable fishing effort (i.e. total net length per season) in order to meet management objectives in southern Brazil. A hierarchical Bayesian model using integrated nested Laplace approximation (INLA) was employed based on 1427 reported settings from 1999 to 2003 and 2006 to 2009. Hotspot zones were detected and are proposed as no‐fishing zone during the white croaker Micropogonias furnieri and striped weakfish Cynoscion guatucupa gillnet fishing seasons. Their extents represent 6% (1466.8 km2) and 19% (4493.7 km2) of the fishing ground (23 204.1 km2) during croaker and weakfish fishing seasons respectively. The total allowable fishing effort estimated outside the no‐fishing zones were estimated at 541 km (95% credible interval (CrI) [339; 940]) during croaker and 688 km (CrI [312; 2,166]) during weakfish fishing seasons, one order of magnitude lower than the current total fishing effort. The drastic reduction of total fishing effort estimated in this study is largely due to weak protection measures since the gillnet fisheries became the major conservation concern for franciscana by the end of 1970s in southern Brazil. Although the implementation of the proposed exclusion zones and limiting fishing effort will strongly impact the status quo, they were based on the best scientific evidence and on a clearly defined management goal to reduce the risk of the franciscana population’s collapse in southern Brazil.

Lungworms are a common finding in seals and fur seals around the world. However, from existing records, the biogeographical distribution of filaroid helminths appears to be restricted, and these parasites are endemic in only certain areas and species, mainly in the Northern Hemisphere. The occurrence of infection in pinniped species in the Southern Hemisphere is scarce. The objective of this work is to verify the prevalence of lungworms in Arctocephalus australis in waters off the southern coast of Brazil. Twenty subadult specimens of A. australis found recently dead on the southern coast of Brazil were necropsied and their lungs were examined. Parasitic cysts were found in only one specimen (prevalence of 5%). The helminths were morphologically identified as Parafilaroides normani (Metastrongyloidea: Filaroididae). This helminth species has been reported in pinnipeds from Australia, New Zealand and South Africa. This is the first record of P. normani in A. australis and for the western South Atlantic, providing additional data regarding the biogeographic distribution of the parasite.