Otolith δ18O and microstructure analyses provide further evidence of population structure in sardine Sardinops sagax around South Africa
| Autor: | Toyoho Ishimura, Tatsuya Sakamoto, Yonela Geja, Kotaro Shirai, Kosei Komatsu, Carl D. van der Lingen, James Peterson |
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| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
Ecology δ18O 010604 marine biology & hydrobiology Population structure Sardine Aquatic Science Oceanography Microstructure 010603 evolutionary biology 01 natural sciences Boundary current medicine.anatomical_structure medicine Upwelling Ecology Evolution Behavior and Systematics Geology Otolith |
| Zdroj: | ICES Journal of Marine Science. 77:2669-2680 |
| ISSN: | 1095-9289 |
| DOI: | 10.1093/icesjms/fsaa130 |
| Popis: | Sardine Sardinops sagax is an ecologically and economically important Clupeid found off the entire South African coast that includes both coastal upwelling and western boundary current systems. Although the management of the sardine fisheries historically assumed a single, panmictic population, the existence of three, semi-discrete subpopulations has recently been hypothesized. We conducted otolith δ18O and microstructure analyses to investigate nursery habitat temperatures and early life growth rates, respectively, of sardine collected from three biogeographic regions around South Africa’s coast to test that hypothesis. Analyses indicated that for both summer- and winter-captured adults and summer-captured juveniles, fishes from the west coast grew significantly slower in water that was several degrees cooler than those from the south and east coasts. This suggests that mixing of sardines between regions, particularly the west and other coasts, is relatively limited and supports the hypothesis of semi-discrete subpopulations. However, the west-south differences disappeared in the results for winter-captured juveniles, suggesting that differences in early life conditions between regions may change seasonally, and/or that all or most winter-captured juveniles originated from the west coast. Further elucidating the interactions between South African sardine subpopulations and the mechanisms thereof is important for sustainable harvesting of this species. |
| Databáze: | OpenAIRE |
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