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Examining trends in abundance of an over-exploited elasmobranch species in a nursery area closure
Determining the dynamics of ecological communities following periods of anthropogenic change is critical to assessing the effectiveness of management strategies. Several coastal areas in south-eastern Australia were proclaimed shark refuge areas (SRAs) following overfishing of the school shark (Galeorhinus galeus) during the 1940s and 1950s. In conjunction with catch reduction measures, these areas provide spatial protection for juvenile G. galeus. We compared recent (2012-2014) and historic (1991-1997) longline catch rates to determine whether young-of-the year (YOY) and juvenile G. galeus continue to utilise these nursery areas (-42.80° Lat, 147.50° Long). Our data suggest that YOY abundances in the SRAs may have increased or at least have remained stable since the 1990s. Data from research fishing conducted from 1947-56 showed that YOY abundance in the SRA correlated well with overall stock abundance in the past. If this relationship still holds, our longline data indicates that the stock might be showing signs of recovery. However, the present day importance of the SRA to the overall stock recruitment as well as the relationship between YOY abundance in the SRA and stock health need to be resolved before monitoring of YOY abundance in the SRA can be used as a fisheries independent stock assessment tool.
MF17130 Accepted 18 September 2017
© CSIRO 2017