Fisheries long term monitoring program : summary of tiger and endeavour prawn survey results: 1998-2006

Abstract

There are two distinct tiger and endeavour prawn fisheries that extend along the northern Queensland east coast and into Torres Strait: the Torres Strait Prawn Fishery (TSPF) and the northern segment (north of 22° S) of the East Coast Trawl Fishery (ECTF). This document reports on the Torres Strait, and a section of the northern Queensland segment of the ECTF (defined as the section of the Queensland east coast from Cape Flattery 16° S to the tip of Cape York 10.4° S. This section will be referred to as Far North Queensland). The prawn trawl fishery in this Far North Queensland (FNQ) region mainly targets tiger, endeavour and king prawns. These three prawn groups consist of six main species: the brown tiger prawn (Penaeus esculentus), the grooved tiger prawn (Penaeus semisulcatus), the blue endeavour prawn (Metapenaeus endeavouri), the red endeavour prawn (Metapenaeus ensis), the redspot king prawn (Melicertus longistylus), and the western king prawn (Melicertus latisulcatus).
The average annual catch (from 1998–2004) of the tiger and endeavour prawn sector of the northern Queensland ECTF (north of 22° S) is approximately 1700 t of tiger prawns, 1200 t of endeavour prawns and 900 t of king prawns (CFISH data, 1998–2004). For the Torres Strait the average annual catch (from 2000–04) is 675 t of tiger prawns, 1018 t of endeavour prawns and 77 t of king prawns (Taylor et al. 2006). The annual value of the northern Queensland and the Torres Strait prawn fisheries is approximately A$40m (Williams 2002) and A$22m, respectively (McLoughlin 2002).
The initial annual prawn surveys (1998–2000) were a component of the Fisheries Research and Development Corporation project 97/146, conducted by Department of Primary Industries and Fisheries (DPI&F). The project developed a fishery independent sampling procedure for tiger and endeavour prawn stocks in northern Queensland and Torres Strait waters. The DPI&F Long Term Monitoring Program continued the annual prawn surveys, using the same survey procedures and sites. The key objective of the annual prawn surveys is to monitor prawn species, size, distribution and relative abundance in order to contribute to assessments of the status of tiger, endeavour and king prawns in northern Queensland and Torres Strait waters. The surveys also document bycatch in the fishery area to enhance understanding of the fishery’s potential impacts on the ecosystem.
The survey results for FNQ indicate that 1999 and 2005 were years of higher than average tiger prawn recruitment while 2000 was a year of lower than average recruitment. Similarly, for Torres Strait, 2000 was a year of low tiger prawn recruitment whereas 1998, 2005 and 2006 were years of above average recruitment.
The results presented in this report, a previous summary of survey results (Turnbull et al. 2004), and a detailed analysis of both the 1998 to 2002 surveys and commercial catch data (Turnbull et al. 2005) indicate that these surveys are a cost effective tool in providing the data needed to monitor prawn stocks, especially in multi-species fisheries such as the northern Queensland east coast tiger prawn fishery. The survey catch rates can be compared with, and provide confidence in, the trends observed in the commercial harvest data (Turnbull et al. 2005, O’Neill and Turnbull 2006, O’Neill and Leigh 2006) especially for tiger prawns which are considered susceptible to overfishing. It is recommended that the LTMP prawn surveys be continued as they provide an important time-series of fishery independent data that complements the analysis of the commercial fishery data. The survey data complements the commercial harvest data and will assist with the development of species-based assessment and monitoring of the northern Queensland tiger prawn fishery.