The Effects of Environmental Factors and Husbandry Techniques on Roe Enhancement of the New Zealand Sea Urchin, Evechinus chloroticus

<p>The roe of sea urchins (Echinodermata: echinoidea) is a prized seafood in a number of countries around the world, including New Zealand. Increasing fishing pressure on world sea urchin stocks has failed to meet demand. This has led to increasing worldwide interest in roe enhancement of sea urchins. In New Zealand kina (Evechinus chloroticus) have also been heavily fished. However, there are large numbers of poor quality (low gonad index or GI) kina found in kina barrens which are uneconomic to harvest due to low returns. The primary aim of this research was to identify the key holding and environmental conditions for roe enhancement of E. chloroticus to assist in the development of a roe enhancement industry for E. chloroticus to utilise this resource. A series of experiments testing the optimal holding conditions for E. chloroticus in both land- and sea-based holding systems showed that culture depth (3 and 6 m) and removal of the urchins from the water three times per week had no significant effect on gonad growth or urchin mortality. However, exposing E. chloroticus to increased water movement resulted in significantly greater gonad growth in 12 weeks. Increasing water movement is believed to increase the available dissolved oxygen and facilitate the removal of metabolites from around the urchins. Gonad development was not negatively impacted at the maximum stock density tested (6 kg urchin m-2 of internal surface area) and this density is recommended. There are significantly lower running and maintenance costs when E. chloroticus are enhanced in sea-based compared to land-based systems but a full economic analysis is required to assess which is likely to be the more economical option for future roe enhancement. A period of 9 to 12 weeks appears to be the optimal period for roe enhancement in terms of the maximum increase in GI in the shortest time period. Repeated experiments over a 12 month period showed that food availability was the primary driver of roe enhancement (i.e. increase in gonad size) in E. chloroticus. This is followed by seawater temperature, which drives much of the seasonal variation in the gonad size that is observed in wild urchins. This is likely to be due to increased food consumption at higher temperatures. The reproductive stage of E. chloroticus had very little effect on the increase in gonad size of enhanced urchins other than in autumn when gonad growth was slightly lower than in all other seasons. Optimal gonad growth in this study was obtained at 18oC, which was the highest temperature tested. Higher temperatures also resulted in an increase in the rate of progress of the gametogenic cycle of E. chloroticus whilst lower temperatures tended to slow the rate of progress. The effects of temperature on gonad growth (i.e. increased growth at higher temperatures) were consistent across seasons. Photoperiod had minimal effect on gonad growth and the reproductive stage of the urchins over periods of 12 weeks. Photoperiod may still affect gametogenesis of E. chloroticus over longer periods. Low GI kina appear to be capable of significantly larger increases in GI in 10-week periods than high GI kina, as a result of their higher tolerance to stress. This thesis has contributed to improving the technical and economic feasibility of roe enhancement of kina (E. chloroticus) in New Zealand.</p>

The Effects of Environmental Factors and Husbandry Techniques on Roe Enhancement of the New Zealand Sea Urchin, Evechinus chloroticus

<p>The roe of sea urchins (Echinodermata: echinoidea) is a prized seafood in a number of countries around the world, including New Zealand. Increasing fishing pressure on world sea urchin stocks has failed to meet demand. This has led to increasing worldwide interest in roe enhancement of sea urchins. In New Zealand kina (Evechinus chloroticus) have also been heavily fished. However, there are large numbers of poor quality (low gonad index or GI) kina found in kina barrens which are uneconomic to harvest due to low returns. The primary aim of this research was to identify the key holding and environmental conditions for roe enhancement of E. chloroticus to assist in the development of a roe enhancement industry for E. chloroticus to utilise this resource. A series of experiments testing the optimal holding conditions for E. chloroticus in both land- and sea-based holding systems showed that culture depth (3 and 6 m) and removal of the urchins from the water three times per week had no significant effect on gonad growth or urchin mortality. However, exposing E. chloroticus to increased water movement resulted in significantly greater gonad growth in 12 weeks. Increasing water movement is believed to increase the available dissolved oxygen and facilitate the removal of metabolites from around the urchins. Gonad development was not negatively impacted at the maximum stock density tested (6 kg urchin m-2 of internal surface area) and this density is recommended. There are significantly lower running and maintenance costs when E. chloroticus are enhanced in sea-based compared to land-based systems but a full economic analysis is required to assess which is likely to be the more economical option for future roe enhancement. A period of 9 to 12 weeks appears to be the optimal period for roe enhancement in terms of the maximum increase in GI in the shortest time period. Repeated experiments over a 12 month period showed that food availability was the primary driver of roe enhancement (i.e. increase in gonad size) in E. chloroticus. This is followed by seawater temperature, which drives much of the seasonal variation in the gonad size that is observed in wild urchins. This is likely to be due to increased food consumption at higher temperatures. The reproductive stage of E. chloroticus had very little effect on the increase in gonad size of enhanced urchins other than in autumn when gonad growth was slightly lower than in all other seasons. Optimal gonad growth in this study was obtained at 18oC, which was the highest temperature tested. Higher temperatures also resulted in an increase in the rate of progress of the gametogenic cycle of E. chloroticus whilst lower temperatures tended to slow the rate of progress. The effects of temperature on gonad growth (i.e. increased growth at higher temperatures) were consistent across seasons. Photoperiod had minimal effect on gonad growth and the reproductive stage of the urchins over periods of 12 weeks. Photoperiod may still affect gametogenesis of E. chloroticus over longer periods. Low GI kina appear to be capable of significantly larger increases in GI in 10-week periods than high GI kina, as a result of their higher tolerance to stress. This thesis has contributed to improving the technical and economic feasibility of roe enhancement of kina (E. chloroticus) in New Zealand.</p>

The Maturity of Female Gonads of G2 Transgenic Mutiara Catfish (Clarias sp.)

The G2 trangsenic Mutiara catfish (Clarias sp.) (MTG) is a Mutiara catfish that is inserted with the CgGH gene (Clarias gariepinus Growth Hormone) through the transgenesis. The effect of transgenesis stimulates gonad growth of G2 transgenic Mutiara catfish (Clarias sp.) faster than non-transgenic fish. Study aimed to analyze the maturity of the gonads and the spawning ability of female G2 transgenic Mutiara catfish (Clarias sp.) to obtain superior broodstock candidates. Experimental method with completely randomized design (pair of parents used as treatment and repeated four times) for spawning was used for this study. Three pairs of parent G2 were crossed semi-artificially as treatment A (female 1 MTG G2 crossed with male 1 MTG G2), B (female 2 MTG G2 crossed with male 2 MTG G2) and C (female 3 MTG G2 crossed with male 3 MTG G2). The results showed that the performance of female G2 transgenic Mutiara catfish (Clarias sp.) (treatment A, B and C) was higher given non-transgenic with an average relative fecundity of 82,438 eggs / kg of broodstock, an average egg diameter of 1.76 mm and an average egg weight 1.75 mg. These indications suggest that GH transgenesis increases gonadal maturity. The gonad maturity profile reached the stage of complete maturity (full ripe) compared to Sangkuriang catfish (Clarias gariepinus) (immature gonads). Therefore it is necessary to compare the reproductive performance of G2 transgenic Mutiara catfish (Clarias sp.) with non-transgenic fish (Sangkuriang) as candidates for superior broodstock of catfish.

Identification and expression of gonadotrophin hormones in gouramy (Osphronemous gouramy, Lacepède, 1801) under photoperiod manipulations

Prayogo NA, Siregar AS, Sukardi P, Bessho Y. 2020. Identification and expression of gonadotrophin hormones in gouramy (Osphronemoous gouramy, Lacepède, 1801) under photoperiod manipulations. Biodiversitas 21: 1365-1372. The environment influences fish reproduction. One of the influential environmental factors is photoperiod that regulates the production of hormones for gonad growth and development, gametogenesis, then the reproductive cycle. This research was conducted to determine the effect of photoperiod on the reproductive performance of gouramy with different photoperiod treatments. The design of this study was four photoperiod treatments consisting of 14L: 10D, 16L: 8D and 18L: 6D and controls. Fish samples were divided into 4 aquariums consisting of nine fish and repetition was conducted on each. Fish were kept under photoperiod treatment for 16 weeks. The observed variable was pituitary activity. Pituitary activity was evaluated by measuring the expression of FSH and LH genes using Real Time PCR. The results showed that gouramy had FSH and LH genes with 483 bp and 506 bp. FSH and LH gene expression increased with long photoperiod exposure (P <0.05). These findings indicate that photoperiods regulate the reproduction of gouramy through the HPG axis and control the production of the hormone Gonadotropin.

The gonad growth of Anguilla bicolor bicolor induced by hormone combination of HCG, MT, E2, and antidopamine

<p class="NoParagraphStyle" align="center"><strong>ABSTRACT</strong></p><p class="NoParagraphStyle" align="center"><strong> </strong></p><p class="NoParagraphStyle">The aim of the study was to stimulate eel gonad growth by intramuscularly injection with a hormonal combination of human chorionic gonadotropin (hCG), methyltestosterone (T), estradiol (E₂) and antidopamine (A) meanwhile 0.9% NaCl solution was used as control. Estradiol concentration in the blood serum were measured by enzyme-linked immunosorbent assay (ELISA). Stimulation with hCG 20 IU/kg in combination with MT 3 mg/kg and 10 μg/kg antidopamine (hTA treatment) very effective for increased the growth of gonads with indicators gonadosomatic index (GSI) of 4.80%, hepatosomatic index 1.01% and concentration of E₂ 2.49±0.67 ng/mL were significantly different (P&lt;0.05) than others treatment after ten weeks of application.</p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle">Key words: hormone, gonad growth, maturation, Indonesian short finned eel</p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle" align="center"><strong>ABSTRAK</strong></p><p class="NoParagraphStyle"> </p><p class="NoParagraphStyle">Penelitian ini bertujuan untuk mengetahui pertumbuhan gonad yang distimulasi oleh kombinasi <em>human chorionic gonadotropin</em> (hCG), metiltestosteron (MT), estradiol (E₂) dan antidopamin (A). Ikan sidat disuntik dengan hormon dan 0,9% NaCl sebagai kontrol secara intramuskular. Pengukuran konsentrasi hormon E₂ dalam serum darah dengan <em>enzyme-linked immunosorbent assay </em>(ELISA). Stimulasi dengan hCG 20 IU/kg dikombinasi dengan MT 3 mg/kg dan antidopamin 10 μg/kg (perlakuan hTA) sangat efektif untuk feminisasi dan meningkatkan pertumbuhan gonad dengan indikator indeks gonadosomatik (GSI) 4,80%, indeks hepatosomatik 1,01% dan konsentrasi E₂2,49±0,67 ng/mL, secara signifikan berbeda pada taraf P&lt;0,05 dibandingkan perlakuan lain setelah sepuluh minggu aplikasi.</p><p class="NoParagraphStyle"> </p><p>Kata kunci: hormon, pertumbuhan gonad, maturasi, sidat</p>