Abstract
Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic) between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant differences were found between seasons, probably as a result of an increment of population in the spring during the recruitment season. The analysis of size distribution revealed that the carapace length (CL) ranged from 2.45 to 28.61 mm and that mean female size consistently exceeded that of males. Differences in mean CL were statistically significant between depth strata and seasons. Of the specimens sampled, 57.00% were males, 41.88% females and 1.42% undetermined. Sex ratio also differed significantly between seasons according to depth strata, consolidating the hypothesis of the existence of seasonal migrations related with the reproductive cycle of this species. Ovigerous females showed larger sizes and occurred all year around and remain in shallow waters in winter, summer and autumn and move to deeper waters in spring. The highest frequency of ovigerous females was recorded in summer, between 151 and 200 m deep supporting the hypothesis that spawning of this species occurs in shallow waters, especially in late summer.
Highlights
Plesionika narval (Fabricius, 1787) is acknowledged by FAO as a species of interest to fisheries (Holthuis, 1980)
P. narval is exploited in a small scale artisanal fishery in Madeira (Biscoito, 1993), the Canary Islands (González et al, 1997) and the Mediterranean Sea (Arculeo et al, 2002)
Our study indicated that larger specimens of P. narval were more predominant in Madeira archipelago compared to specimen size reported by González et al (1997) for the Canary Islands
Summary
Plesionika narval (Fabricius, 1787) is acknowledged by FAO as a species of interest to fisheries (Holthuis, 1980). P. narval is exploited in a small scale artisanal fishery in Madeira (Biscoito, 1993), the Canary Islands (González et al, 1997) and the Mediterranean Sea (Arculeo et al, 2002). This species occurs from the surface down to 910 m of depth in a large variety of habitats including muddy, sand-muddy, rocky bottoms and submarine caves (Holthuis, 1987; Thessalou-Legaki, 1989; Biscoito, 1993). Awareness on the life cycle strategies of a population, the vertical distribution and sexual segregation appear to be fundamental in establishing regulatory measures to the management of stocks and in the selection of appropriate fishing strategies for each target species (Thessalou-Legaki, 1989; Carbonell and Abelló, 1998)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
