Implications for fishery management in small tunas the case of genetic population structure of bullet tuna in the west Mediterranean

Knowledge of population structure of species is needed to establish appropriate management regulations. Of particular concern are those commercial species; these exploited fish populations can undergo loss of genetic variability that ultimately may lead the loss of regional small populations. This situation could occur in the small tuna species, which in some cases are heavily targeted by artisanal fisheries. Here, we focused on the Bullet tuna (Auxis rochei) with an extensive sampling (n = 431) along the north and south coast of the west Mediterranean and one location on the east Atlantic. The analysis of the mtDNA control region revealed that seven (about 1.6%) individuals were not identified as Bullet tuna suggesting a species misidentification with possible implications in stock assessment. Population genetics results showed clear genetic differentiation between the Iberian Peninsula and North African locations. These results have a clear impact on the conservation and management strategies, and if it is confirmed in other small pelagic species, the pattern of population structure in the Mediterranean is more complex than initially expected