Reproductive biology of the vulnerable species Sciaena umbra Linnaeus, 1758 (Pisces: Sciaenidae)
2009
Amàlia Grau | Marta Linde | Antoni Mª Grau
Reproductive biology of the brown meagre, Sciaena umbra, is described based on 171 specimens caught by trammel nets and spear gun from April 1998 to October 2000. Histological examination and gonadosomatic index suggest that the spawning season of the brown meagre in Balearic waters is from May to August and peaks in May and June. Seven stages of gonadal development were identified: immature, early developing, late developing, running, spent, recovering and resting. The frequency distribution of oocyte diameter reveals that brown meagre is an iteroparous, gonochoristic, seasonal multiple-spawning fish with aynchronous oocyte development. Size at first maturity was 25.4 cm of total length for males and 29.9 cm for females. Sex ratio varied with fish size, with a tendency for greater numbers of females in higher size classes. Weight-length relationships for both sexes, as well as for the total population, were significantly allometric positive. An analysis of the monthly variations of hepatosomatic index (HSI), and Le Cren’s condition factor showed that HSI is not a good indicator of the lipid reserves of S. umbra. According to our results, current management measures for this species should be re-evaluated.
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