Habitat Uses and Migratory Patterns of Patagonian Chondrichthyans: New Conservation Strategies Based on Satellite Telemetry

19 May 2011 San Antonio Oeste, Argentina, Central and Latin America Fishes | Marine

Juan Martin Cuevas

The aim of the project is to create new conservation strategies for sharks and rays of the San Matias Gulf (Patagonia) based on their habitat uses and migratory patterns using satellite technology. This information and the commercial fishery fleet movements will be linked on time and space in a GIS.

G galeus female tagged.

G galeus female tagged.

The main threats for the conservation of the Patagonian sharks and rays are related with the non regulated fishery (direct and indirect): commercial, artisan or sportive, and the lack of ecological data. Today a fishery focused specifically over sharks in Patagonian waters doesn't exist, however many sharks species are extracted as bycatch of the argentine hake Merluccius hubssi. The Patagonian rays are in a more critically conservation state due to the direct fishery by longline and by indirect fishery as shrimp bycatch, both added to the coast artisan fishery are creating today one of the greatest world captures.

The knowledge of the habitat use and migration patterns (trophic and reproductive) of Patagonian sharks and rays will be linked in a geographical information system (GIS). Thus, this system will contribute to build with the national stakeholders (Federal Fishery Council) new conservation and management strategies to be applied for these species. The present project will also bring relevant information about the ecological interactions between the top predators in the Patagonian marine ecosystem. The information related with the habitat uses of sharks and rays will allow linking it with the trophic ecology data available of these species and estimate, in a non direct way, the impact over the ecosystem.

We will analyse the habitat uses and migration patterns of the vulnerable shark Galeorhinus galeus and the threatened ray Atlantoraja castelnaui using satellite marks: PAT (Popup Archival Transmitting). The individuals will be captured using their specific type of fishing gear and during its season occurrence in their particular sites (coast or off-shore). All specimens captured and marked will be identified at its species level, sexed and measured (Total Length). All capturing sites will be georeferenced using a GPS. The PAT mark records depth, temperature and light intensity of the environment. The collection of the data will be made for a maximum of 12 months by the satellite system ARGOS. To determine the habitat use of the species we will calculate the total days spent by each individual at each site and depth using the Kernel density estimation.

Today, the main difficult that faced biologists and stakeholders to manage and preserve sharks and rays species and their populations in the world is the lack of ecological information, work tools and political will.

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