Browsing by Author "Sousa, Inês Mendes de Andrade Araújo de"
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- Life history parameters and valorisation of a low commercial value fish species: the case study of piper gurnard, Trigla lyra Linnaeus 1758Publication . Sousa, Inês Mendes de Andrade Araújo de; Sequeira, Vera; Andrade, José PedroMany fishing activities involve high discarding rates constituting, a major problem for the marine ecosystem. Trigla lyra presents low commercial value in Portuguese landings and is mainly caught as accessory species in trawls, trammel nets, traps and pots. Published information on this species in Portuguese waters is scarce. So, the main objectives of the present study are to contribute to the knowledge of biological, namely age and growth and reproduction, and chemical parameters of T. lyra. Approximately 30 specimens were collected monthly from fishing vessels operating off Peniche (West coast of Portugal). The study of age and growth involved age estimation using whole sagitta otoliths, marginal increment ratio (MIR) and otolith edge type analysis, determination of length-weight relationship and estimation of parameters of the von Bertalanffy growth model. Regarding reproduction, the structure of the gonads was studied, and reproductive strategy was characterized, including the definition and duration of spawning season and determination of fecundity type. Chemical composition of the muscle was determined in terms of moisture, ash content, protein content, total fat and profile of fatty acids. MIR and otolith edge type analysis suggest that a single set of translucent and opaque increments is formed every year in T. lyra otoliths. There was a lack of small individuals in the sample, leading to the application of three adjustment methods for estimating growth parameters, with back-calculation being the best method. Sex ratio analysis indicated higher abundance of females in relation to males. Spawning season occurred between November and February and fecundity type was found to be determinate. The species proved to be beneficial regarding protein content but especially regarding fatty acid content, with the results indicating high EPA and DHA concentrations. The present study contributed to improve the knowledge on biological and chemical parameters of T. lyra in Portuguese waters, essential for its exploration and future valorisation.