Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.1/1680
Título: Reproductive biology of the species Leucoraja naevus from Portuguese continental waters
Autor: Maia, Catarina
Orientador: Erzini, Karim
Figueiredo, Ivone
Palavras-chave: Cuckoo ray
Reproductive season
Oviducal gland
Reproductive strategy
Data de Defesa: 2010
Resumo: Skate populations tend to be highly vulnerable to exploitation as a result of the main life history characteristics (slow growth, late maturity and low fecundity). The cuckoo ray, Leucoraja naevus, one of the skate species landed in Portugal, is mainly a by-catch species from the artisanal mixed-fishery, and for this reason it is very difficult to acquire information about its basic biology. The two main goals of the present work were to estimate the length at first maturity, fecundity and reproductive cycle of the species Leucoraja naevus and to compare the microscopic structure and chemical nature of the secretions produced by the oviducal gland of the species Leucoraja naevus with other skate species taking into account their reproductive strategy. Although the species has been studied in other NE Atlantic geographic areas, namely Celtic Sea, Irish Sea and North Sea, this study is the first to provide information on the reproductive biology of Leucoraja naevus in Southern European waters. Length at first maturity was estimated at 57 cm and 55 cm TL for males and females, respectively. Active females were observed in every months of the year suggesting that reproduction may occur year round, with a reproductive peak during winter months between January and April. Females release follicles in batches of 5. However, it was not possible to determine the number of reproductive episodes realized by a female during a 1-year period. Leucoraja naevus, Raja brachyura, Raja miraletus, Raja undulata, Raja microocellata and Raja montagui, have similar microscopic structure divided in four zones: club, papillary, baffle and terminal. However, differences were found between Leucoraja naevus and the remaining species in the chemical nature of the secretions produced in the papillary zone, that seems to have a higher content of sulphated acid mucins, and in the terminal zone that, like in Raja microocellata, lacks serous gland tubules. The differences found are related with the reproductive strategy displayed by each species, namely with the capsule and spawning habitats characteristics. Sperm was found in all species as laterally aligned bundles in the deep recessed tubules of the baffle zone, adjacent to the muscle layer, suggesting short-term sperm storage. These results provide essential information on the reproductive biology not only about the species Leucoraja naevus but also about other by-catch species inhabiting Portuguese continental waters and, therefore, constitute an important tool for a proper management plan.
Descrição: Dissertação de mest., Biologia Marinha, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2010
Peer review: yes
URI: http://hdl.handle.net/10400.1/1680
Designação: Mestrado em Biologia Marinha
Aparece nas colecções:UA01-Teses

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