A depth-dependent assessment of annual variability in gonad index, reproductive cycle (gametogenesis), and roe quality of the green sea urchin (Strongylocentrotus droebachiensis) in Breiðafjörður, Iceland

• Main Author: O´Hara, Tasha Eileen, 1984-
• Other Authors: Háskólinn á Akureyri
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Meistaraprófsritgerðir; Háskólasetur Vestfjarða; Haf- og strandsvæðastjórnun; Skrápdýr; Veiðistjórnun; Skollakoppur; Coastal and marine management; Green sea urchin; University Centre of the Westfjords; Haf; Breiðafjörður; Iceland; North Atlantic
• Online Access: http://hdl.handle.net/1946/34021

Verkefnið er lokað til 01.06.2021. The commercial fishery for the green sea urchin (Strongylocentrotus droebachiensis) is small, but high-value in North-Atlantic nations, including Iceland. Research on this species and fishery has been very limited in Iceland. Increased knowledge of the species growth, utilization possibilities, and development of the fishery is important for sustainable management and utilization. The aim of this study was to assess whether depth had an impact on sexual development, the quality of urchin gonads, and whether market quality urchins could be found at greater depths than usually fished in Breiðafjörður, west Iceland. In order to evaluate the differences in sexual development and gonad quality between depths, green sea urchins were collected monthly at 32 and 60 m depth during September 2016 to August 2017. Development and spawning time at both depths investigated were determined by examining monthly changes in gonad index (GI), gametogenesis (nutritive vs. gamete cell development) and sexual stage progression. The results indicated that the gonad index followed the same annual rhythm at both depths investigated and exceeded minimum market standards (10%) at both sites during harvest months (August-March). However, the mean GI was 12-48% higher at lower depth from August to March. Similarly, the results from investigating histology slides showed that gamete development and sexual stages were similar between the two depths investigated, suggesting that depth may not significantly impact sexual development and gametogenesis. Spawning onset was found to occur in both sites between the March and April. Sex was not found to significantly impact gametogenesis in most months at both sites. Sex ratios were nearly 1:1 overall and at both depth sites, with no observed incidences of hermaphroditism. Gonad colors were ranked according to market standards and were found to meet or exceed minimum market standards from August to March, with a very low incidence of unacceptable coloration. The ...