Occurrence and population structure of sharks in two ecologically or biologically significant marine areas off north-eastern Brazil

Occurrence and population structure of sharks in two ecologically or biologically significant marine areas off north-eastern Brazil

Laís R. Barcellos, Rodrigo Barreto, Rosângela PT Lessa

ABSTRACT:

1. Ecologically or Biologically Significant Marine Areas (EBSAs) are rare, and highly important sites to the life history of a number of declining shark species are endangered by fishing.
2. The high diversity of sharks caught by fisheries is difficult to monitor due to the scarcity of information on species-specific biological aspects (growth, maturity and fertility rate).
3. There are two EBSAs off north-eastern Brazil, where key species are caught, more specifically the oceanic whitetip (Carcharhinus longimanus), mako (Isurus oxyrinchus), blue (Prionace glauca) and silky (Carcharhinus falciformis) sharks. Another 23 species displaying low frequency in catches have also been recorded, many of them considered threatened according to the IUCN Red List and the Brazilian Ministry of Environment.
4. The main purpose of this study was to generate information about shark diversity and demonstrate the role of the two EBSAs in their conservation. After analysing fishing data collected from 2000 to 2011, maps were built to categorize shark species by phases of their ontogenetic development (neonate, young and adult) based on samples of C. falciformis (n = 330), C. longimanus (n = 440), I. oxyrinchus (n = 452) and P. glauca (n = 8,176).
5. Shark stocks comprised mainly juveniles, which raises concerns since they are considered a crucial life stage for the sustainability of shark populations. Catch monitoring also highlighted that several of the species caught are threatened and their catch is either prohibited or limited according to the Brazilian laws and international rules in place.
6. Action plans and enforcement of laws and rules are needed to deliver the protective measures needed for shark species in these EBSAs.

Aquatic Conservation, DOI: 10.1002/aqc.3787

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