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

We provide 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 utilizing three ageing protocols achieved good agreement between three rounds of readings (average percent error = 1.45%). Growth of spiny dogfish was best described by the Gompertz growth model and the following parameters: k values for males and females were 0.08 and 0.04 year-1, respectively, size-at-birth was from 22.2 to 24.2 cm total length, with a theoretical asymptotic length of 74.9 cm for males and 114.0 cm for females. The age at which 50% of the population is sexually mature 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 and 0.07 for males and females, respectively. Due to 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.

elasmobranch; ageing; growth models; spine

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