Life history traits of the narrow-barred Spanish mackerel (Scomberemorus commerson) across jurisdictions of the southeast Arabian Peninsula: Implications for regional management policies

The narrow-barred Spanish mackerel (Scomberomorus commerson) is a large neritic predatory fish targeted by several thousand artisanal boats across eight jurisdictions in the Arabian Gulf, Gulf of Oman, and Arabian Sea. First steps have been taken for a regional management of the stock across some of these jurisdictions. However, although the drive for regional management may be justified on the grounds of probable transborder population processes, it may err by ignoring smaller spatial scales in the structuring of stocks that function as meta-populations. We carried out a comparative analysis of life history traits of the narrow-barred Spanish mackerel using newly collected data as well as published data encompassing a region from the northern Arabian Gulf to the eastern Arabian Sea. We obtained substantial differences in somatic growth and reproduction processes while rates of natural mortality were homogeneous. In addition we show differences in length composition of the catch reflecting different levels of exploitation. Our results imply that management should be conducted primarily at the level of each national jurisdiction while regional-wide initiatives could be useful to resolve scientific issues about population structure.