Migrations and habitat use of the smooth hammerhead shark (Sphyrna zygaena) in the Atlantic Ocean

PLoS One. 2018 Jun 6;13(6):e0198664. doi: 10.1371/journal.pone.0198664. eCollection 2018.

Abstract

The smooth hammerhead shark, Sphyrna zygaena, is a cosmopolitan semipelagic shark captured as bycatch in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. From 2012 to 2016, eight smooth hammerheads were tagged with Pop-up Satellite Archival Tags in the inter-tropical region of the Northeast Atlantic Ocean, with successful transmissions received from seven tags (total of 319 tracking days). Results confirmed the smooth hammerhead is a highly mobile species, as the longest migration ever documented for this species (> 6600 km) was recorded. An absence of a diel vertical movement behavior was noted, with the sharks spending most of their time at surface waters (0-50 m) above 23°C. The operating depth of the pelagic longline gear was measured with Minilog Temperature and Depth Recorders, and the overlap with the species vertical distribution was calculated. The overlap is taking place mainly during the night and is higher for juveniles (~40% of overlap time). The novel information presented can now be used to contribute to the provision of sustainable management tools and serve as input for Ecological Risk Assessments for smooth hammerheads caught in Atlantic pelagic longline fisheries.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Migration / physiology*
  • Animals
  • Atlantic Ocean
  • Behavior, Animal / physiology*
  • Ecological Parameter Monitoring / methods
  • Female
  • Fisheries
  • Geographic Information Systems
  • Male
  • Motor Activity / physiology*
  • Remote Sensing Technology
  • Risk Assessment / methods
  • Sharks / physiology*

Grants and funding

Financial support for this study was provided by Oceanário de Lisboa through Project “SHARK-TAG: Migrations and habitat use of the smooth hammerhead shark in the Atlantic Ocean”. Rui Coelho is supported by an Investigador-FCT contract (Ref: IF/00253/2014) from the Portuguese Foundation for Science and Technology (FCT, Fundação para a Ciência e Tecnologia) supported by the EU European Social Fund and the Programa Operacional Potencial Humano. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.