Reproductive biology of the female spiny dogfish (Squalus acanthias, Linnaeus 1758) in the Eastern Adriatic Sea

Arbanas, Lucija (2009) Reproductive biology of the female spiny dogfish (Squalus acanthias, Linnaeus 1758) in the Eastern Adriatic Sea. Diploma thesis, Faculty of Science > Department of Biology.

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Abstract

Female specimens of spiny dogfish (Squalus acanthias L.) have been caught in the period between 2005 and 2007 in the Eastern Adriatic Sea by on-board observers on five commercial bottom trawls. Fishing vessels were operating in area between 44°32’ and 43°44’ N, and 15°05’ and 14°40’ E. We sampled 100 sharks, and collected material for laboratory analysis. The purpose of this investigation was to find out some new features about reproductive biology of a female spiny dogfish in the Eastern Adriatic Sea, a species who is commercially fished without knowing its biology and life cycle. Results showed that length of females were ranging from 26.10 to 112.00 cm (average 58.45 ± 22.59). Based on gonad morphometry we can suppose that females reach sexual maturity at about 65 cm length. We isolated between 5 - 28 eggs from the ovary (average (16.80 ± 6.45, N=21), with egg diameter ranging from 1.78 to 35.98 mm. Embryos were sampled from 7 females. Litter size ranged between 6 - 18, (average 10.14 ± 4.22), while lengths of embryos ranged from 12.20 to 21.50 cm (average 15.85 ± 2.56). The sex ratio of embryos was biased towards females (1.3 : 1). Based on these results we can not establish all details on reproductive biology of females, especially because we have no previous data for comparison. Therefore, further investigation of subadult and adult females need to be encouraged. These stages are mostly exposed to fishing activities, they represent the basis of the sustainable population, and need to be properly protected.

Item Type: Thesis (Diploma thesis)
Keywords: Squalus acanthias, spiny dogfish, reproductive biology, east Adriatic Sea
Supervisor: Lacković Venturin, Gordana
Date: 2009
Number of Pages: 40
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 12 Sep 2014 08:15
Last Modified: 16 Feb 2016 14:05
URI: http://digre.pmf.unizg.hr/id/eprint/2729

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