An integrated monitoring program for the Northern Prawn Fishery 2011

Marine and Estuarine Ecology (incl. Marine Ichthyology)

Kenyon, Rob ; Burridge, Charis ; Van Der Velde, Tonya ; Donovan, Anthea ; Fry, Gary ; Tonks, Mark ; Cheers, Sue

CSIRO Marine and Atmospheric Research

DOI  :  10.4225/08/584c43c07ea2c
RP-ID  :  EP117911

学科分类：地球科学(综合)

澳大利亚|英语

来源: CSIRO Research Publications Repository

【 摘 要 】

An international review of the Northern Prawn Fishery (NPF) tiger prawn assessment was carried out in 2001. The review drew attention to the high level of uncertainty in the assessment and recommended that the logbook data be augmented by fishery-independent survey data. In response to the review, industry funded a consultancy project in 2002 to investigate and design an integrated monitoring program for the NPF. Following an industry meeting, NORMAC decided to conduct a one-year pilot survey in 2002/03. The project (FRDC 2002/101) was funded through the FRDC, and included a spawning index survey in August and a recruitment index survey in January. The success of the pilot project led to subsequent FRDC-funded monitoring projects (FRDC 2003/075 in 2003/04, FRDC 2004/099 in 2004/05) and AFMA-funded projects (AFMA R05/0599 in 2005/06; AFMA R05/1024 in 2006/08 and AFMA R08/0827 in 2008/10).These projects (AFMA 09/0863 and AFMA R10/0822) are a continuation of the NPF prawn monitoring program and they are funded by AFMA, the industry and CSIRO.Two surveys were undertaken during the 2011 calendar year, in January/February and July.The timing of the surveys matches key phases of the annual life cycle of the prawns.In general, the ‘effective spawning’ of commercial prawns in the Gulf of Carpentaria occurs from August to December.Postlarvae advect inshore and settle to shallow estuaries and embayments from September to March.Emigrant juveniles that contribute strongly to the subsequent fishery move from the inshore nursery habitats to offshore from roughly November to March, particularly November to January for banana prawns.Once offshore, they grow and move to deeper waters over time. The ‘recruitment survey’ in late January/February measures the abundance of smaller prawns that have emigrated from the nursery habitats and are found in the shallower regions of the fishing grounds early in the year.The ‘spawning survey’ in July (August prior to and including 2004) measures the abundance and spawning condition of large adults that are found on the fishing grounds just prior to the second fishing season.In the case of tiger prawns, they will be fished in the up-coming season.While in the case of banana prawns, they are a remnant spawning population from fishing during the first season (April-June).For the ‘recruitment’ and ‘spawning’ surveys conducted in 2011, we used the sampling frames and randomly selected sites as in previous years. All surveys adopted the same stratification in which the strata are defined by subregion and water depth (for details see Ye et al. 2004; 2005).Indices of prawn abundance are created from both surveys.The indices for tiger and endeavour prawns from both the recruitment and spawning surveys are incorporated directly into the NPF stock assessment.The size-frequency data from the surveys are critical to the recently developed size-structured model that supports the assessment.The spawning surveys also provide fishery independent data to monitor any change in fishing power in the NPF.Recruitment-Index SurveyThe recruitment-index survey is a substantial undertaking: two boats sampled a total of 300 sites in five regions (partitioned into 24 strata) between 25th January and 11th February 2011.To avert being caught in the potential path of Cyclone Yasi, we changed the order in which sites were sampled, and in spite of this disruption there was no loss of fishing time. Given the survey length, number of people involved and the wide geographic spread of sites to be sampled, the capacity to achieve this is testimony to the discipline, knowledge and experience of the survey team and vessel crews and management.