When plenty is not enough: an assessment of the white stumpnose (Rhabdosargus globiceps) fishery of Saldanha Bay,South Africa |
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Authors: | D Parker SE Kerwath TF Næsje CJ Arendse FJ Keulder-Stenevik K Hutchings |
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Institution: | 1. Fisheries Management Branch, Department of Agriculture, Forestry and Fisheries (DAFF), Cape Town, South Africa;2. Department of Biological Sciences, University of Cape Town, Cape Town, South Africa;3. Norwegian Institute for Nature Research (NINA), Trondheim, Norway;4. South African National Parks, Rondevlei Scientific Services (Garden Route National Park), Sedgefield, South Africa;5. Sars Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway;6. Anchor Environmental Consultants, Cape Town, South Africa;7. Marine Research Institute, University of Cape Town, Cape Town, South Africa |
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Abstract: | White stumpnose Rhabdosargus globiceps is the main target of the linefishery in Saldanha Bay. Increased fishing pressure over the last three decades, particularly by the recreational sector, has led to concerns regarding sustainability of the local white stumpnose stock. The fishery was exceptionally productive between 2006 and 2008, with an estimated annual catch of 141.2 tonnes (t). Only 3% of boat outings surveyed were commercial boats targeting white stumpnose, yet this sector accounted for 39.3 t (31%) of the average annual catch. The recreational boat sector accounted for most of the catch (70.0 t), and the recreational shore sector the least (31.9 t). Commercial boat catch per unit effort (CPUE; 3.7 fish angler–1 h–1) was more than 10 times that of recreational boats (0.3 fish angler–1 h–1). White stumpnose catch length-frequency differed significantly (p < 0.01) between the fishing sectors, with the commercial sector retaining larger fish (34.7 cm SD 5.9]) than the recreational boat (33.9 cm SD 5.9]) and shore (30.4 cm SD 5.8]) sectors. A decline in commercial CPUE (2000–2015) of approximately 40% and a concomitant severe decline (>95%) in survey data for juvenile white stumpnose CPUE (2007–2016) indicate that the current rate of exploitation is not sustainable. Recovery of the white stumpnose stock will require a decrease in fishing mortality. Possible management regulations include sector-specific effort limitations, extending the ‘no take’ marine protected area, reducing the recreational-sector bag limit to 5 fish person–1 day–1, implementing a commercial-sector bag limit, and increasing the minimum size limit to 30 cm TL. |
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Keywords: | angling annual yield catch and effort Langebaan Lagoon linefish recruitment survey roving creel survey temperate sparid |
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