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Partial female migration and cool-water migration pathways in an overfished shark

journal contribution
posted on 2023-05-20, 01:21 authored by McMillan, MN, Huveneers, C, Jayson SemmensJayson Semmens, Gillanders, BM

Knowledge about reproductive movements can be of important conservation value for over-exploited species that are vulnerable when moving between and within key reproductive habitats. Lack of knowledge persists around such movements in the overfished school shark Galeorhinus galeus in Australia. Management assumes all pregnant females migrate between adult aggregations in the Great Australian Bight, South Australia, and nursery areas around Bass Strait and Tasmania. We tracked 14 late-term pregnant females tagged in South Australia using satellite-linked pop-up archival tags to investigate extent, timing, and routes of migrations. We found partial migration, with some females (n = 7) remaining near aggregating areas throughout the pupping season, some migrating to known nursery areas (n = 3), and one migrating ∼3 000 km to New Zealand. We conclude female movements and pupping habitats are less spatially constrained than assumed and propose females use cool-water routes along the shelf break to reduce energy costs of migration. Migrating females using these routes faced greater fishing pressure than sharks in inshore areas and were not protected by inshore shark fishing closures designed to protect them. This study demonstrates the complexity of reproductive movements that can occur in wide-ranging species and highlights the value of explicit movement data.

History

Publication title

ICES Journal of Marine Science

Volume

76

Issue

4

Pagination

1083-1093

ISSN

1054-3139

Department/School

Institute for Marine and Antarctic Studies

Publisher

Academic Press Ltd Elsevier Science Ltd

Place of publication

24-28 Oval Rd, London, England, Nw1 7Dx

Rights statement

© International Council for the Exploration of the Sea 2018. All rights reserved.

Repository Status

  • Restricted

Socio-economic Objectives

Fisheries - wild caught not elsewhere classified

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