Evidence for population complexity of the European anchovy (Engraulis encrasicolus) along its distributional range

The European anchovy, Engraulis encrasicolus, is one of the most commercially relevant fisheries resources in many countries bordering the northeast Atlantic coasts and the Mediterranean Sea. However most of its fishery stocks are currently fully exploited or overexploited and understanding its population structure is necessary for designing appropriate management regulations in fisheries. Investigation of otolith shape analysis from 15 localities across most of the anchovy range distribution revealed a complex population structure. Four distinct groups of anchovy were identified with an overall correct classification of 83%. Group A: North Sea and English Channel; group B: Mauritania and southeast Atlantic Morocco; group C: northeast Atlantic Morocco-Gulf of Cadiz-south Alboran-Algero-Provençal coasts; and group D: northern Mediterranean Sea. However, at smaller spatial scales, more complex population structure was hypothesized in the Mediterranean Sea, mainly in relation to oceanographic features. The results support the usefulness of otolith shape analysis for population structure analysis both at larger and smaller spatial scales where genetic studies generally fail to discriminate between local groups of fish. From a management perspective, these local and isolated groups of fish may have unique demographic properties and should be managed separately since they may react independently to exploitation.