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Interactions between marine mammals and fisheries are a growing problem, and effective management requires assessment of the factors driving the interaction and of the impacts on fisheries. We used data from interactions between artisanal fisheries and bottlenose dolphins around the Balearic Islands to assess these factors and impacts. Observers collected data during 1,040 fishing operations over 3 yr. Location and year were important factors affecting interaction probability, with some areas showing large increases over the study period. We estimated the combined cost of catch loss and net damage as 6.5% of the total catch value (95% CI −12.3%, −1.6%), and the annual loss to be 3.4% (95% CI −6.5%, −0.1%) of the total catch by weight. This weight equates to the dietary needs of ∼12 dolphins (95% CI 0.2, 22), suggesting the fishery is not a vital food source for the dolphin population. Two dolphins died through entanglement during the observed fishing operations. We observed 3% of the total fishing activity, by weight, in 2003; scaling up this mortality directly suggests that as many as sixty dolphins may be dying in nets each year. This interaction likely has serious conservation implications for the dolphin population.

2 imedeA (CSiC-uiB), instituto mediterráneo de estudios Avanzados, C/ miquel marquès 21, 07190, esporles, Spain.SummArY: 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.Keywords: Sciaena umbra, teleostean fishes, reproduction, spawning period, histology, mediterranean Sea, Balearic islands.reSumen: Biología reproductiva de la especie vulnerable Sciaena umbra Linnaeus, 1758 (Pisces: Sciaenidae).-Se ha estudiado la biología reproductiva de Sciaena umbra a partir de ejemplares capturados mediante trasmallo y arpón durante el periodo 1998-2000. el examen histológico y el índice gonadosomático sugieren que la época de puesta del corvallo en Baleares comprende los meses de mayo a agosto, presentando un pico de actividad reproductiva de mayo a junio. Se han identificado siete estadios de desarrollo gonadal: inmaduros, en desarrollo inicial, en desarrollo final, en puesta, agotamiento, recuperación y reposo. la frecuencia de distribución del diámetro del ovocito muestra que el corvallo es una especie iterópara, gonocórica, estacional, de múltiples puestas y desarrollo ovocitario asincrónico. la talla de primera madurez fue de 25.4 cm (longitud total) para los machos y de 29.9 cm para las hembras. la proporción de sexos varió en relación a la talla, con tendencia a favor de las hembras al aumentar la talla. la relación talla-peso de ambos sexos y de la población, fue alométrica positiva. el estudio de las variaciones mensuales en el índice hepatosomático (iHS) y el índice de condición de le Cren indicó que el iHS no es un buen indicador de las reservas lipídicas de S. umbra. Según nuestros resultados, las medidas actualmente vigentes para esta especie deberían ser revisadas.

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