Effort analysis. In Rothlisberg PC and Okey TA (eds). Variation in banana prawn catches at Weipa: a comprehensive regional study
Loneragan, N. (2006) Effort analysis. In Rothlisberg PC and Okey TA (eds). Variation in banana prawn catches at Weipa: a comprehensive regional study. CSIRO Marine and Atmospheric Research, Cleveland, Australia, pp 45-50.
When commercial prawn fishing began in the Gulf of Carpentaria in the early 1960s, it initially targeted only the banana prawn (Penaeus merguiensis) ~ a species that formed dense aggregations that stir the sediment, making visible mud ‘boils’. Catches of P. merguiensis peaked at more than 12,000 t in 1974 and have remained high, although they fluctuate from year to year (Dichmont et al. 2006). These large catches, together with open access to the fishery (which attracted large foreign vessels in the 1960s and 70s) and government boat-building subsidies, resulted in the fishing fleet growing to about 280 vessels in the early 1980s (Figure 5-14). Furthermore, because P. merguiensis is short-lived and aggregates, the fishery made substantial investments in processing and targeting equipment. The increased efficiencies led to the allowable number of fishing days being reduced from year round in the 1960s, to a few months in the 1970s, and to just over a month in the 1990s and thereafter (Somers and Wang 1997).
Data from the logbooks were explored using simple linear regression analysis to detect whether there had been major changes in the relationship between catch and effort over three decades of the Weipa fishery and the available years of data since 1999. If the slope of the line has changed over time it suggests that fishing effectiveness (catchability) has changed, while a change in the intercept indicates that the available biomass has changed. Trends in the relationships were compared between Weipa (Stock 11) and Karumba (Stock 9) regions to see whether the relationship between catch and effort was consistent between these two regions.
|Murdoch Affiliation:||Centre for Fish and Fisheries Research
School of Biological Sciences and Biotechnology
|Series Name:||FRDC Final Report for Project 2004/024|
|Publisher:||CSIRO Marine and Atmospheric Research|
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