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Type: Journal article
Title: Historical changes in mean trophic level of southern Australian fisheries
Author: Alleway, H.
Connell, S.
Ward, T.
Gillanders, B.
Citation: Marine and Freshwater Research, 2014; 65(10):884-893
Publisher: CSIRO Publishing
Issue Date: 2014
ISSN: 1323-1650
Statement of
Heidi K. Alleway, Sean D. Connell, Tim M. Ward and Bronwyn M. Gillanders
Abstract: 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.
Keywords: Fisheries; fisheries catch; ‘fishing down’; marine food webs; South Australia
Rights: Journal compilation © CSIRO 2014
RMID: 0030015051
DOI: 10.1071/MF13246
Appears in Collections:Earth and Environmental Sciences publications

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