RESULTS

Alterations in the normal gonad anatomy and architecture of male individuals of European sardine, Sardina pilchardus, were registered in five of 509 specimens analysed (total prevalence of 0.98%): Northern Spain (GSA 6) n = 2 (N = 100, local prevalence of 2%), Northern Adriatic Sea (GSA 17) n = 2 (N = 203, local prevalence of 0.99%), and Aegean Sea (GSA 22) n = 1 (N = 206, local prevalence of 0.49%) (GSA average prevalence ± SD of 1.16 ± 0.63 %) (Tab. I). Gonadal gross morphology analysis revealed that these five individuals presented three asymmetric testicular lobes (Fig. 2A, B, C). Individuals had two main gonad lobes and an additional one of smaller size, the latter adopting a rope-like shape overlapping one of the two main lobes, and weakly connected to the posterior part, which constitutes the spermatic duct. Two males (Northern Spain 15.1 cm TL (Fig. 2B) and Aegean 15 cm TL (Fig. 2A)) showed to be at developing reproductive phase, characterized by easily identified testes close to reach the spawning capability, while the remaining three individuals (Northern Spain 13.9 cm TL, and Northern Adriatic 13.7 and 13.8 cm TL) were at spawning capable phase (actively spawning subphase), with firm testes where accumulation of sperm in the spermatic ducts was macroscopically visible (e.g. Fig. 2C, D, E, F). In the latter, the sperm was macroscopically detected in a disposition and quantity similar to that of normal testicles in all lobes, supported by the histological analysis, that revealed the presence of spermatids and the release of sperm by all the subunits, including the additional of smaller size.