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SUMMARY: The present study reports the growth rate of the purple dye murex, Bolinus brandaris (Gastropoda: Muricidae), estimated from mark-recapture experiments. A total of 1067 specimens (shell length = 43.4±8.1 mm, range = 14.6−78.4 mm) were marked with Dymo ® tape tags and released in a semi-intensive fish culture earthen pond. After a period at liberty ranging from almost two months to around two years, 288 individuals were recaptured (shell length = 67.4±6.2 mm, range = 45.3−88.6 mm), which corresponded to a recapture rate of 27.0%. At recapture, only one specimen had lost the tag (tag loss rate <0.1%) and all remaining tags were intact and legible. Mean monthly growth rates were 0.9±1.0 mm in shell length, 0.4±0.5 mm in shell width and 0.7±0.7 g in total weight. Growth rates showed high inter-individual variability and an evident decreasing trend with specimen size. Comparison of growth rates with similar information available for other muricids confirmed that B. brandaris is a relatively slow-growing species. This provides valuable information for both fisheries management and for assessing the potential of B. brandaris as a candidate species for molluscan aquaculture.Keywords: purple dye murex, Bolinus brandaris, Gastropoda, Muricidae, mark-recapture, growth rate. RESUMEN: Crecimiento de la cañailla, Bolinus Brandaris (Gastropoda: Muricidae), mediante técnicas de marcado-recaptura realizadas en estanques de cultivo semiintensivo de peces. -Se ha estudiado el crecimiento de la cañailla Bolinus brandaris (Gastropoda: Muricidae) mediante técnicas de marcado-recaptura. Se marcaron un total de 1067 individuos (longitud concha = 43.4±8.1 mm, rango = 14.6−78.4 mm) con etiquetas plásticas Dymo, que fueron puestos en libertad en un estanque en tierra dedicado al cultivo semiintensivo de peces. En el plazo de tiempo comprendido entre dos meses y dos años, se recuperaron 288 ejemplares (longitud concha = 67.4±6.2 mm, rango = 45.3−88.6 mm), lo que corresponde a una tasa de recaptura del 27.0%. Las etiquetas permanecieron intactas y legibles en todos los ejemplares recuperados, a excepción de un único individuo (tasa de pérdida de marca <0.1%). La tasa de crecimiento media mensual estimada fue de 0.9±1.0 mm de longitud, 0.4±0.5 mm de anchura y 0.7±0.7 g de peso total. Esta tasa muestra una elevada variabilidad intraespecífica y una tendencia clara a la disminución con el aumento de la talla. Comparando las tasas de crecimiento obtenidas en este estudio con la información disponible sobre diversas especies de murícidos, se confirma que B. brandaris es un gasterópodo de crecimiento relativamente lento. Este estudio resulta de interés tanto para gestionar la pesca de este recurso como para evaluar el potencial de la especie como candidata a ser cultivada.

International audienc

No abstract

Gaspar, M. B., Carvalho, S., Constantino, R., Tata-Regala, J., Cúrdia, J., and Monteiro, C. C. 2009. Can we infer dredge fishing effort from macrobenthic community structure? – ICES Journal of Marine Science, 66: 2121–2132. The effects of commercial fishing effort (FE) on macrobenthic community structure were analysed in geographically related fishing grounds separated into three groups: non-exploited (NE), moderately exploited (ME), and highly exploited (HE). Number of species, abundance, Margalef species richness, and Shannon–Wiener diversity were significantly higher in NE than in exploited areas. The first two were also significantly higher in HE than in ME areas. Measures of taxonomic diversity differed depending on whether annelids, molluscs, and crustaceans were combined or analysed separately. Crustaceans seemed to be the most vulnerable to bivalve dredging because significantly lower values were observed for them in the HE areas than in the ME and NE areas for this group. Although the samples were taken at the end of the closed season, macrobenthic communities still showed differences that may be related to FE, especially in trophic structure. Carnivory was particularly dominant in HE areas. The ratio of carnivory to filter-feeding was significantly correlated with FE, with higher values being observed in HE areas and lower values in NE areas.