Early life-history strategy of Cape hake in the Benguela upwelling region
- 作者：B. Grote ; W. Ekau ; W. Hagen ; J.A. Huggett ; H.M. Verheye
- 关键词：Cape hake ; Merluccius capensis ; Merluccius paradoxus ; Early life-history strategy ; Optimal environmental window ; Upwelling ; Benguela current ; South Africa
- 刊名：Fisheries Research
- 出版年：2007
- 期刊代码：45_01657836
- 类别：abs
- 出版时间：September 2007
- 卷：86
- 期：2-3
- 页码：179-187
- 文件大小：1128 K
摘要
The spatial and temporal variability of the egg and larval abundance of Merluccius spp. in the Benguela Jet Current was analysed. The Cape hakes, occurring in waters off South Africa, are important for the commercial fisheries in the southern Benguela system, but information on their early life-history strategy is sparse. Data and samples, for this study, were collected during bimonthly cruises of the South African Sardine and Anchovy Recruitment Project (SARP) from August 1995 to July 2003. Samples were collected with a mini-bongo net (300 μm mesh) on a transect crossing the Benguela Current off the Cape Peninsula at 34.15°S, 18.29°E extending 58 nm offshore. Eggs and larvae were commonly found in currents with north-westerly flow, suggesting that the Benguela Jet Current transports eggs and larvae of Merluccius spp. to the northern nursery areas. Spawning grounds of Merluccius spp. appeared to be on the western Agulhas Bank during August 1996 to July 1998. Two possible spawning grounds in different water depths were identified, suggesting spawning by both Cape hake species, M. capensis and M. paradoxus. Peak abundances of eggs and larvae of Merluccius spp. were found from June to October, a time of reduced offshore transport. Abundances of eggs and larvae were low in austral summer and autumn. Spawning intensity was higher during times of reduced upwelling as shown by correlations of abundances of early life stages with the upwelling index. This leads to the assumption that the early life-history strategy of Merluccius spp. is well adapted to the variability in upwelling intensity.