Title

Satellite Telemetry Reveals Higher Fishing Mortality Rates Than Previously Estimated, Suggesting Overfishing of an Apex Marine Predator

Document Type

Article

Publication Date

8-16-2017

Publication Title

Proceedings of the Royal Society B: Biological Sciences

Keywords

Conservation, Fisheries, Isurus oxyrinchus, Mortality, Shortfin mako shark, Stock assessment

ISSN

0962-8452

Volume

284

Issue/No.

1860

First Page

1

Last Page

8

Abstract

Overfishing is a primary cause of population declines for many shark species of conservation concern. However, means of obtaining information on fishery interactions and mortality, necessary for the development of successful conservation strategies, are often fisheries-dependent and of questionable quality for many species of commercially exploited pelagic sharks. We used satellite telemetry as a fisheries-independent tool to document fisheries interactions, and quantify fishing mortality of the highly migratory shortfin mako shark (Isurus oxyrinchus) in the western North Atlantic Ocean. Forty satellite-tagged shortfin mako sharks tracked over 3 years entered the Exclusive Economic Zones of 19 countries and were harvested in fisheries of five countries, with 30% of tagged sharks harvested. Our tagging-derived estimates of instantaneous fishing mortality rates (F = 0.19–0.56) were 10-fold higher than previous estimates from fisheries-dependent data (approx. 0.015–0.024), suggesting data used in stock assessments may considerably underestimate fishing mortality. Additionally, our estimates of F were greater than those associated with maximum sustainable yield, suggesting a state of overfishing. This information has direct application to evaluations of stock status and for effective management of populations, and thus satellite tagging studies have potential to provide more accurate estimates of fishing mortality and survival than traditional fisheries-dependent methodology.

Comments

©2017 The Author(s) Published by the Royal Society. All rights reserved.

Additional Comments

Florida Sea Grant award #: UFDSP00010205

ResearcherID

G-4080-2013

DOI

10.1098/rspb.2017.0658

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