Reproduktivna biologija ženki kostelja (Squalus acanthias, Linnaeus 1758) u istočnom Jadranu

master's thesis

• Title (english): Reproductive biology of the female spiny dogfish (Squalus acanthias, Linnaeus 1758) in the Eastern Adriatic Sea
• Author: Lucija Arbanas
• Mentor: Gordana Lacković-Venturin (mentor)
• Committee member: Gordana Lacković-Venturin (predsjednik povjerenstva)
• Committee member: Zoran Tadić (član povjerenstva)
• Committee member: Božena Mitić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2009, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

U istočnom Jadranu u razdoblju od 2005. do 2007. godine prikupljane su jedinke ženki morskog psa kostelja (Squalus acanthias L.). Istraživano područje je obuhvaćalo istočni dio Jadrana, odnosno Lošinjski akvatorij između 44°32’ i 43°44’ sjeverno, te 15°05’ i 14°40’ istočno, a životinje su prikupljane na ribarskim brodovima, koćaricama. Morfometrijski je obrađeno 100 životinja, te su prikupljeni uzorci za daljnju laboratorijsku obradu. Cilj istraživanja je bio doznati pojedinosti o reproduktivnoj biologiji ženki kostelja u istočnom Jadranu, vrsti koja se intenzivno izlovljava, a čiji životni ciklus još nije poznat. Rezultati pokazuju da se veličina ulovljenih ženki kretala u rasponu od 26.10 do 112.00 cm (srednja vrijednost 58.45 ± 22.59). Na temelju morfometrije gonada pretpostavlja se da ženke dostižu spolnu zrelost kod veličina od oko 65 cm dužine. Iz jajnika je u prosjeku izolirano od 5 do 28 jaja (srednja vrijednost 16.80 ± 6.45, N=21), a promjer jaja se kretao od 1.78 do 35.98 mm. Embriji su pronađeni u uterusu 7 ženki. Najveći zabilježeni broj embrija po ženki je 18, a najmanji 6 (srednja vrijednost 10.14 ± 4.22), a raspon dužina embrija se kretao između 12.20 i 21.50 cm (srednja vrijednost 15.85 ± 2.56). Odnos spolova embrija je više u korist ženki (1.3:1). Na temelju ovog istraživanja teško je donijeti detaljne zaključke o reproduktivnom ciklusu ženki, budući da podaci za usporedbu o toj vrsti u Jadranu uopće ne postoje. Stoga su nužna daljnja istraživanja, pogotovo za juvenilne i odrasle jedinke. Njihov opstanak je posebice ugrožen ribolovnim aktivnostima, a osnova su održanja populacije i potrebno ih je primjereno zaštititi.

Abstract (english)

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.

• Keywords: Squalus acanthias; kostelj; reproduktivna biologija; istočni Jadran
• Keywords (english): Squalus acanthias; spiny dogfish; reproductive biology; east Adriatic Sea
• Language: croatian
• URN:NBN: urn:nbn:hr:217:320170
• Study programme: Title: Biology; specializations in: Ecology; Course: Ecology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra biologije (magistar/magistra biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-03-05 13:44:59