Abundance and population structure of Plesionika narval (Fabricius, 1787) in the Northeastern Atlantic

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...

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Bibliographic Details
Published in:Brazilian Journal of Biology
Main Authors: R. Sousa, M. R. Pinho, J. Delgado, A. R. Pinto, M. Biscoito, T. Dellinger, P. Henriques
Format: Article in Journal/Newspaper
Language:English
Published: Instituto Internacional de Ecologia 2018
Subjects:
Plesionika narval
pandalídeos
estrutura populacional
composição tamanhos
Madeira
Science
Q
Biology (General)
QH301-705.5
Zoology
QL1-991
Botany
QK1-989
narval
Online Access:https://doi.org/10.1590/1519-6984.179610
https://doaj.org/article/a091793a29dd440ead846ae04421bb72
Description
Summary: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.

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