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Historical changes in mean trophic level of southern Australian fisheries

journal contribution
posted on 2023-05-21, 03:53 authored by Alleway, HK, Connell, SD, Timothy WardTimothy Ward, Gillanders, BM
Decreases in the mean trophic level (MTL) of fishery catches have been used to infer reductions in the abundance of high trophic level species caused by fishing pressure. Previous assessments of southern Australian fisheries have been inconclusive. The objectives of the present study were to provide more accurate estimates of MTL using disaggregated taxonomic and spatial data. We applied the model of MTL to fisheries catch statistics for the state of South Australia from 1951 to 2010 and a novel set of historical market data from 1936 to 1946. Results show that from 1951 to 2010, MTL declined by 0.16 of a trophic level per decade; a rate greater than the global average of 0.10 but equivalent to similar regional investigations in other areas. This change is mainly attributable to large increases in catches of sardine, rather than reductions in the catches of high trophic level species. The pattern is maintained when the historical data is included, providing a time line from 1936 to 2010. Our results show a broadening of the catch of lower trophic levels and suggest care in interpretation of MTL of catches because reductions do not necessarily reflect change in high trophic level species by fishing pressure.

History

Publication title

Marine and Freshwater Research

Volume

65

Issue

10

Pagination

884-893

ISSN

1323-1650

Department/School

Institute for Marine and Antarctic Studies

Publisher

C S I R O Publishing

Place of publication

150 Oxford St, Po Box 1139, Collingwood, Australia, Victoria, 3066

Rights statement

Journal compilation copyright CSIRO 2014

Repository Status

  • Restricted

Socio-economic Objectives

Marine biodiversity

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