Age and growth dynamics of spiny dogfish, Squalus acanthias, in the Adriatic Sea (Eastern Mediterranean Sea)

This research provides the first information on age and growth estimates for the endangered Mediterranean subpopulation of spiny dogfish, a commercially exploited shark, highly sensitive to overexploitation. We collected samples from 206 specimens caught by commercial bottom trawls in the Adriatic Sea, and utilising three ageing protocols achieved good agreement between the readings (average percentage error = 1.65%). Four growth models were fitted to length-at-age and weight-at-age data, for each sex separately. The Gompertz growth model produced the statistically best fit resulting in the following parameters: k values for males and females were 0.09 and 0.04 year(-1), size-at-birth ranged from 22.9 to 24.1-cm total length, with a theoretical asymptotic length of 103.3 cm for males and 173.3 cm for females. The age at 50% maturity was 10.5 years for males and 20.1 years for females. The maximum age was estimated at 23 years for males and 36 years for females, with natural mortality estimates of 0.12 for males and 0.07 for females. As a result of reported demographic parameter estimates, high fishing effort and particularly low resilience of the species to exploitation, it is important to produce proper species-specific management strategy for the spiny dogfish in the region.