MEPS

Marine Ecology Progress Series

MEPS is a leading hybrid research journal on all aspects of marine, coastal and estuarine ecology. Priority is given to outstanding research that advances our ecological understanding.

Online: ISSN 1616-1599

Print: ISSN 0171-8630

DOI: https://doi.org/10.3354/meps

Journal contents
Mar Ecol Prog Ser

Nearshore essential habitat of threatened sharks around a temperate oceanic island

ABSTRACT: Nursery habitats are important to many fish populations by ensuring optimal conditions for the survival and growth of juveniles. Protection of these habitats can be critical to the conservation of endangered fish species. We investigate potential essential habitats for early life stages of smooth hammerhead, Sphyrna zygaena, and tope, Galeorhinus galeus, two highly migratory and endangered shark species. The study focusses on an oceanic island in the Azores archipelago, North Atlantic, where a nursery area for 2 to 4-year-old smooth hammerhead has been recently described. Baited remote underwater video systems and scientific longline fishing were used to sample across a depth range of 30–135 m on the island shelf. Young-of-the-year sharks were identified based on body size measurements. A primary smooth hammerhead nursery area was found to exist within the larger nursery site. Smooth hammerhead of different sizes were segregated spatially, suggesting an ontogenetic shift in habitat use. In contrast, tope were not confined to the nursery area but seemed to use the entire island shelf as an essential habitat. Juvenile tope had a balanced sex-ratio, while mature individuals were predominantly females. This study provides a first description of habitat use of natal smooth hammerhead and juvenile tope around an oceanic island in the mid-Atlantic. The results of this study highlight that Faial Island is an essential habitat for critical life history stages of both species, and the Azores Archipelago might have a more important role for the North Atlantic populations of these sharks than previously thought.

KEYWORDS

Diya Das (Corresponding Author)

  • Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Prof. Doutor Frederico Machado No. 4, 9901-862 Horta, Portugal
diyadas.d@gmail.com, diya.das@uac.pt

Robert Priester (Co-author)

  • Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Prof. Doutor Frederico Machado No. 4, 9901-862 Horta, Portugal
robert.priester@posteo.de

Joana Soares (Co-author)

  • Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Prof. Doutor Frederico Machado No. 4, 9901-862 Horta, Portugal
joanahortasoares@hotmail.com

Bruno Macena (Co-author)

  • Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Prof. Doutor Frederico Machado No. 4, 9901-862 Horta, Portugal
brunomacena@hotmail.com

Jorge Fontes (Co-author)

  • Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Prof. Doutor Frederico Machado No. 4, 9901-862 Horta, Portugal
jorge.mr.fontes@uac.pt, fontes04@gmail.com

Pedro Afonso (Co-author)

  • Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Prof. Doutor Frederico Machado No. 4, 9901-862 Horta, Portugal
pafonsopim@gmail.com

Handling Editor:
Elliott Hazen, Pacific Grove, California, USA

Reviewers:
M. Schaber and 2 anonymous referees