Black scabbardfish,Aphanopus carbo,is a commercially important species that takes distant migrations throughout its life cycle.Sex steroids were measured by radioimmunoassay in the blood plasma of specimens caught off...Black scabbardfish,Aphanopus carbo,is a commercially important species that takes distant migrations throughout its life cycle.Sex steroids were measured by radioimmunoassay in the blood plasma of specimens caught off the Madeira Archipelago and mainland Portugal to link this species migratory path with its reproductive cycle.Furthermore,a pilot study using Mozambique tilapia(Oreochromis mossambicus)was designed to evaluate the effect of sample freshness on steroid levels because black scabbardfish blood was collected at separate times after specimens were caught.The changes in T and 11-KT concentrations between the time of blood extraction and the time after preservation did not statistically differ among the different methods applied.Therefore,measured black scabbardfish steroid concentrations were directly used in the subsequent data analyses.In females,E2 and in T concentrations peaked at a late stage of vitellogenesis.E2 concentration was significantly different between females caught off each area.Clustering E2 and T concentrations from all developing females resulted in the separation of two distinct groups,independently of their geographical area.In males,T and 11-KT were not significantly different between maturity stages.The hepatosomatic index of males caught off mainland Portugal was relatively high.This may reflect a mechanism for storing energy that will later be consumed during migration to the spawning grounds.The trend of sex steroids concentrations throughout the sexual maturation of the species is consistent with the morphological indicators and shows evidence of the reproductive and migratory pattern hypothesised for the black scabbardfish in NE Atlantic.展开更多
基金This work was supported by the Portuguese Foundation for Science and Technology(FCT-Fundaçāo para a Ciência e Tecnologia)under the PhD Grant SFRH/BD/64434/2009 to I.Fa.and the project UID/Multi/04326/2013 to A.V.M.C.the Portuguese Government Development Investments and Expenses Program(PIDDAC-Programa de Investimentos e Despesas de Desenvol-vimento da Administraçāo Central)under the EU/DG Fisheries’Data Collection Framework(DCF)the Portuguese Fisheries Operational Program(2007-2013)(PROMAR-Programa Operacional Pescas),cofinanced by the European Fisheries Fund(EFF)(2007-2013),under project CERTIFICA(2011-2015),MSC Certification in Portugal-Acquiring the knowledge and studying the viability for its application to coastal and artisanal fisheries.
文摘Black scabbardfish,Aphanopus carbo,is a commercially important species that takes distant migrations throughout its life cycle.Sex steroids were measured by radioimmunoassay in the blood plasma of specimens caught off the Madeira Archipelago and mainland Portugal to link this species migratory path with its reproductive cycle.Furthermore,a pilot study using Mozambique tilapia(Oreochromis mossambicus)was designed to evaluate the effect of sample freshness on steroid levels because black scabbardfish blood was collected at separate times after specimens were caught.The changes in T and 11-KT concentrations between the time of blood extraction and the time after preservation did not statistically differ among the different methods applied.Therefore,measured black scabbardfish steroid concentrations were directly used in the subsequent data analyses.In females,E2 and in T concentrations peaked at a late stage of vitellogenesis.E2 concentration was significantly different between females caught off each area.Clustering E2 and T concentrations from all developing females resulted in the separation of two distinct groups,independently of their geographical area.In males,T and 11-KT were not significantly different between maturity stages.The hepatosomatic index of males caught off mainland Portugal was relatively high.This may reflect a mechanism for storing energy that will later be consumed during migration to the spawning grounds.The trend of sex steroids concentrations throughout the sexual maturation of the species is consistent with the morphological indicators and shows evidence of the reproductive and migratory pattern hypothesised for the black scabbardfish in NE Atlantic.
