• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.894-899
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• 2020

This study investigated the effects of inclusion of pollock oil (PO) in the diet of broodstock on the egg and larval quality of Walleye Pollock Gadus chalcogrammus. The experimental diet comprised of semi-moist pellets prepared either with or without PO (control; Con). The fish assigned to each diet were fed to visual satiation (two meals per day) for 12 weeks. Eggs spawned from both groups of fish were sampled during the spawning season (three months) and the egg and larval quality was determined. Total egg volume, fertilization, and hatchability of eggs from the PO group were higher than those of the Con group. Fatty acid composition of fertilized eggs was not affected by the experimental diet. Oleic acid, eicosapentaenoic acid, and docosahexaenoic acid content in larvae of the PO group was higher than that in larvae of the Con group. These results demonstrate the beneficial effects of including PO in the broodstock diet of Walleye Pollock, specifically on the quality of the eggs (total egg volume, fertilization, and hatchability) and larvae (fatty acid composition).

• The Korean Journal of Malacology
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• v.27 no.2
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• pp.143-148
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• 2011

Even though ark shell, Scapharca broughtonii is commercially important species, its artificial seed production is not yet fully developed. This study was carried out to understand the effect of three microalgal species on gonadal development and sex maturation of S. broughtonii in terms of broodstock management and food organism. Isochrysis galbana, Phaeodactylum tricornutum and Tetraselmis tetrathele were supplied to S. broughtonii broodstock in single or mixed. And condition index, gonadal development, sexual maturation and survival of the broodstock were analysed. After 45 rearing days, frequency of ripe stage of gonadal phases, rate of induced sexual maturation and survival of S. broughtonii broodstock fed mixed diet with 3 microalgal species or single diet of T. tetrathele were the highest.

• Fisheries and Aquatic Sciences
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• v.25 no.12
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• pp.619-625
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• 2022

The study carried out a 15-day feeding trial of the fleshy shrimp broodstock that have just finished their first spawn using five different maturation feed types (three types of manufactured feed, fresh feed, and commercial feed) to induce multiple spawning in the shrimp and then analyzed and compared hemolymph levels of total protein, total lipid, hemocyanin, glucose, and cholesterol as well as ovary histology between the treatments to identify the potential of the experimental diets to be utilized as maturation feed. The study found that the manufactured diets of polychaetes + clam and polychaetes + clam + squid resulted in significantly higher levels of lipid and protein in shrimp hemolymph suggesting an indicator of multiple spawning in the fleshy shrimp. The other manufactured diet of polychaets + squid led to the highest 2nd spawning with significantly lower levels of lipid, protein, and cholesterol in shrimp hemolymph. The fresh feed treatment showed similar hematological as well as histological responses to the manufactured diet of polychaetes + squid, but with a significantly lower spawning volume compared to the other treatments. The study demonstrated that the manufactured diets could replace fresh feed as maturation feed and attain a higher shrimp maturation than the commercial feed.

• Journal of Aquaculture
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• v.11 no.3
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• pp.303-310
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• 1998

The growth and survival rate of larvae and juveniles from female rockfish (Sebastes schlegeli) broodstock in vitellogenesis by injection of 3,5,3'-triiodo-L-thyronine $T_3$ with a dose of 20 mg/kg fish wt. were examined for 30 days and compared with sham-control fish injected dime-thyl sulfoxide and control fish. Larvae were fed with rotifers for first 5 days after parturition, rotifers and Artemia nauplii for next 10 days. And then, they were fed with Artemia nauplii and commercial diet. Growth of larvae and juveniles from maternal $T_3$injection was significantly faster than that of two controls, nevertheless, the condition factor was lower than that of controls. The whole body proximate analyses indicated that there were significant effects of $T_3$ injection on protein and lipid, but no significant on moisture and ash contents. Survival rate of the fish from maternal $T_3$injection was significantly higher than that of fish from the two controls. These results indicate that thyroid hormone supplements appear to confer a distinct advantage to larval and juvenile rockfish in early, fragile development stage.

• Journal of Aquaculture
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• v.19 no.1
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• pp.25-32
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• 2006

An experiment was carried out to investigate changing of water quality during the seed production of dark-banded rockfish Sebastes inermis in large scale tanks. Ten broodstock of dark-banded rockfish were held in three circular tanks (diameter 6.5 m; depth 2 m; water volume 50 ton) each (stocking density $0.061kg/m^3$). During the experiment the temperature ranged from 14.2 to $16.1^{\circ}C$. The fingerlings were 134 with rotifers only during 1 to 9 days after parturition, rotifers with Artemia nauplii during 10 to 20 days after parturition, Artemia nauplii only during 21 to 35 days after parturition, Artemia nauplii with commercial diet during 36 to 80 days after parturition and commercial diet only during 81 to 85 days after parturition. Water quality (dissolved oxygen, pH, $NH_4^+-N,\;NO_2^--N,\;NO_3^--N\;and\;PO_4^{3-}-P$) in rearing tanks measured every 5 days in long term monitoring investigation or every 2 hours in diurnal monitoring investigation. In 85 days after parturition, the body weight of fish grew up to 0.88 f and specific growth rate was 8.0%/day in body weight. In long term monitoring investigation, with the increase of the amount of supplied commercial diet, the concentration of dissolved oxygen (DO) and pH decreased, but the concentration of $NH_4^+-N\;(4.5\;to\;76.3{\mu}M),\;NO_2^--N\;(0.02\;to\;0.06{\mu}M),\;NO_3^--N\;(3.0\;to\;5.9{\mu}M)$, and $PO_4^{3-}-P\;(0.41\;to\;0.59{\mu}M)$ increased. In the diurnal monitoring investigation, the concentration of $NH_4^+-N$ showed great fluctuation and ranged from 3.0 to $9.1{\mu}M$ when fed rotifers, 16.3 to $45.8{\mu}M$ when fed Artemia nauplii and 36.5 to $120.1{\mu}M$ when fed commercial diet. After daily feeding with each of feed, the amount of dissolved inorganic nitrogen (DIN) and phosphorus (P) wastage were 7.0 g and 0.7 g when fed rotifers, 24.7 g and 0.7 g when fed Artemia nauplii and 140.9 g and 2.2 g when 134 commercial diet. The amount of DIN and phosphorous wastage during 134 commercial diet was significantly higher than that of fed rotifer and Artemia nauplii (P<0.05). Results will provide valuable information far water quality management and culture of dark-banded rockfish in commercial seed production systems.