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An overview on the role of Hexanchiformes in marine ecosystems: biology, ecology and conservation status of a primitive order of modern sharks

journal contribution
posted on 2023-05-17, 11:31 authored by Barnett, A, Braccini, JM, Cynthia AwruchCynthia Awruch, Ebert, DA
The large size, high trophic level and wide distribution of Hexanchiformes (cow and frilled sharks) should position this order as important apex predators in coastal and deep-water ecosystems. This review synthesizes available information on Hexanchiformes, including information not yet published, with the purpose of evaluating their conservation status and assessing their ecological roles in the dynamics of marine ecosystems. Comprising six species, this group has a wide global distribution, with members occurring from shallow coastal areas to depths of c. 2500 m. The limited information available on their reproductive biology suggests that they could be vulnerable to over-exploitation (e.g. small litter sizes for most species and suspected long gestation periods). Most of the fishing pressure exerted on Hexanchiformes is in the form of commercial by-catch or recreational fishing. Comprehensive stock and impact assessments are unavailable for most species in most regions due to limited information on life history and catch and abundance time series. When hexanchiform species have been commercially harvested, however, they have been unable to sustain targeted fisheries for long periods. The potentially high vulnerability to intense fishing pressure warrants a conservative exploitation of this order until thorough quantitative assessments are conducted. At least some species have been shown to be significant apex predators in the systems they inhabit. Should Hexanchiformes be removed from coastal and deep-water systems, the lack of sympatric shark species that share the same resources suggests no other species would be capable of fulfilling their apex predator role in the short term. This has potential ecosystem consequences such as meso-predator release or trophic cascades. This review proposes some hypotheses on the ecology of Hexanchiformes and their role in ecosystem dynamics, highlighting the areas where critical information is required to stimulate research directions.

History

Publication title

Journal of Fish Biology

Volume

80

Issue

5

Pagination

966-990

ISSN

0022-1112

Department/School

Institute for Marine and Antarctic Studies

Publisher

Wiley-Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, OX4 2DQ, UK

Rights statement

Copyright 2012 The Fisheries Society of the British Isles

Repository Status

  • Restricted

Socio-economic Objectives

Assessment and management of terrestrial ecosystems

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