کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6385175 | 1626786 | 2016 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: A novel approach for estimation of the natural mortality of the common whelk, Buccinum undatum (L.) and role of hermit crabs in its shell turnover A novel approach for estimation of the natural mortality of the common whelk, Buccinum undatum (L.) and role of hermit crabs in its shell turnover](/preview/png/6385175.png)
Analysis of simultaneously occurring live molluscs and empty shells of the whelk Buccinum undatum indicated similar abundance on the seabed making possible the estimation of recent natural mortality. Nearly all empty shells were occupied by hermit crabs Pagurus bernhardus and most of the remainder by Pagurus prideaux. P. bernhardus is highly selective for robust whelk shells, whereas anemone-protected P. prideaux use a range of smaller and thin-walled shells. Application of age size keys based on age reading of opercula surfaces permitted a tentative estimate of natural mortality of MÂ =Â 1.34 on trap fishing grounds for brown crab in the southwest North Sea (whelks aged 4-7 years) and MÂ =Â 0.85 and MÂ =Â 0.63 for the fishing grounds on the Western Waters (whelks aged 4-7 years and 4-9 years respectively). Estimates of total mortality (Z), based on size-frequencies of live whelks, were ZÂ =Â 1.35 (North Sea) and ZÂ =Â 1.46 and 1.23 (Western Waters, aged 4-7 years and 4-9 years). Estimates of M for the North Sea might be biased by differences in trap selectivity between hermit crabs and live whelks. This is a novel approach that might be developed for whelk fisheries assessment and management, particularly using better age determination techniques.
Journal: Fisheries Research - Volume 183, November 2016, Pages 146-154