Abundance indices for main commercial fish species caught by trawl from the south-eastern Australian continental shelf from 1918 to 1957
Neil L. KlaerCSIRO Division of Marine Research, GPO Box 1538, Hobart, Tas. 7001, Australia. Email: neil.klaer@csiro.au
Marine and Freshwater Research 55(6) 561-571 https://doi.org/10.1071/MF03182
Submitted: 5 November 2003 Accepted: 30 June 2004 Published: 14 September 2004
Abstract
Per-haul records of catches by steam trawlers on the south-eastern Australian continental shelf from 1918 to 1957 were examined for the main commercial species tiger flathead (Neoplatycephalus richardsoni), jackass morwong (Nemadactylus macropterus), redfish (Centroberyx affinis), latchet (Pterygotrigla polyommata) and chinaman leatherjacket (Nelusetta ayraudi). Catch rates in weight per haul per species were standardised to annual indices of abundance using a log-linear model. Standardised annual index trends for flathead, latchet and leatherjacket indicate a strong to severe decline during the period covered by the data. All species showed seasonal patterns, but the peak season varied depending on the species. The distribution of standardised catch rate by area also differed greatly by species, and no single area showed consistent differences across all species. Day trawls caught more flathead, redfish and latchet, while night trawls caught more morwong and leatherjacket. Moon phase had less influence on catch rates than other factors. The correlation of annual index trends to a number of annual mean environmental factors was examined and no strong correlations were found.
Extra keywords: catch rate, catch per unit effort (CPUE), generalised linear model (GLM), fisheries management, historical, log-linear model, South East Fishery, steam trawl, stock assessment.
Acknowledgments
The History of Marine Animal Populations sub-project of the Census of Marine Life project of the US Sloan Foundation funded most of this work. Ron Thresher (CSIRO Marine Research) provided the sunspot, SOI, and latitude of the sub-tropical ridge mean annual data series. Mark Bravington (CSIRO Marine Research) gave useful advice on the design and interpretation of the LLM analyses, and Rob Campbell, Peter Thompson (CSIRO Marine Research), Bob Kearney (University of Canberra) and André Punt (University of Washington) provided useful comments on an earlier draft of this paper. Ian Barnes-Keoghan from the Australian Bureau of Meteorology provided access to standardised data sets of mean annual rainfall and temperature by collection station. Mr Richard Mansfield, a former owner of Red Funnel Trawlers Pty Ltd (one of the main steam trawler companies operating in the SEF) supplied company catch records that helped considerably with the interpretation of details in the per-haul data already held.
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