Examining trends in abundance of an overexploited elasmobranch species in a nursery area closure
McAllister, JD and Barnett, A and Lyle, JM and Stehfest, KM and Semmens, JM, Examining trends in abundance of an overexploited elasmobranch species in a nursery area closure, Marine and Freshwater Research, 69, (3) pp. 376-384. ISSN 1323-1650 (2017) [Refereed Article]
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. In the present study, we compared recent (2012–14) and historic (1991–97) longline catch rates to determine whether young-of-year (YOY) and juvenile G. galeus continue to use these nursery areas (42°47′60.00″S, 147°30′0.00″E). 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 to 1956 showed that YOY abundance in the SRA correlated well with overall stock abundance in the past. If this relationship still holds, our longline data indicate that the stock may be showing signs of recovery. However, the present-day importance of the SRA to 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.
catch per unit effort, catch rate, Galeorhinus galeus, prerecruit abundance, recovery, school shark, shark fishery