Industry Survey - Eastern Gemfish

Industry survey to obtain a relative abundance index for spawning eastern gemfish - traditional and innovative methods (AFMA Project R2006/830) Ian Knuckey, Euan Harvey and Matt Koopman (2009)

Eastern gemfish (Rexea solandri) are midwater fish caught along the edge of thecontinental shelf off southern Australiaand New Zealand.  They comprised a very significant proportionof trawl landings off south-eastern Australia during the 1970s and1980s with trawling targeting winter pre-spawning aggregations of maturefish.  Eastern gemfish became the firstspecies in the South East Fishery (SEF) to be subject to a Total AllowableCatch quota in 1988, when a TAC of 3,000t was imposed.  However, in the early 1990s the spawningstock was significantly reduced by a series of very poor cohorts (spawnedbetween 1985 and 1989), and the TAC was progressively reduced to zero by 1993.  The TAC remained at zero for 1994, 1995 and1996 due to concerns about low stock size resulting from an extended period oflow recruitment; however this made it difficult to assess the status of thestock because there had been no valid targeted catch rate data to use as anindex of stock abundance.

Industry strongly suggested that some level ofrecovery of the eastern gemfish stock had occurred. This has subsequently beensupported to some extent by the Integrated Scientific Monitoring Program (ISMP)which reported increased catches and discarding of juvenile gemfish during theearly to mid 2000s.  Industry called forsome type of survey to help quantify thisapparent recovery.  During 2006, both theSlope Resource Assessment Group (SlopeRAG) and Shelf Resource Assessment Group(ShelfRAG) also supported the need for a survey to provide a relative index ofabundance that could be used to compare with the targeted fishing of easterngemfish over a decade earlier and the industry surveys of 1996 – 1998.  This report details the resultsof the Industry survey to obtain a relative abundance index for spawningeastern gemfish using traditional and innovative methods.