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• Effect of cultivation feed diet using local food processing by-products on the growth and flavor factor in the Malabar grouper Epinephelus malabaricus

  Takahashi M.

  Frontiers in Aquaculture ( Frontiers in Aquaculture )  4   2025.08 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Introduction This study investigated the use of locally sourced food processing by-products to formulate sustainable aquaculture feed in alignment with circular economy principles. Methods An experimental diet (Food Waste Diet; FW-D) was formulated using 50% fishmeal from tuna viscera and 20% brewer’s spent yeast (BSY) sourced in Okinawa, Japan. The Malabar grouper (Epinephelus malabaricus) were reared in a recirculating aquaculture system for 8 weeks and compared against a commercial diet (CO-D). Growth performance, liver somatic index, insulin-like growth factor 1 (IGF-1) gene expression, and muscle taste-related components were analyzed. Results FW-D-fed fish showed slightly lower growth performance, possibly due to decreased protein content. However, liver histology revealed no signs of metabolic stress, and IGF-1 gene expression levels were higher in the FW-D group, indicating active growth signaling. FW-D-fed fish also exhibited significantly increased muscle levels of unsaturated fatty acids, particularly docosahexaenoic acid (DHA), a nutrient beneficial for human health. Sensory analysis indicated comparable overall taste quality between the two groups. FW-D fillets had greater chewiness and reduced fishy odor, whereas CO-D fillets were richer in fatty taste. Discussion These findings suggest that FW-D, composed of locally available by-products, can offer a nutritionally advantageous and economically viable alternative to conventional feeds. Despite a slight reduction in growth, the enhanced DHA content and acceptable sensory attributes of FW-D-fed fish support its application in sustainable aquaculture systems. This approach contributes to resource recycling and value creation within a local circular economy.

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• Combined effects of light and salinity on the growth performance in juveniles of the Malabar grouper, <i>Epinephelus malabaricus</i>

  Zhu, YF; Fukunaga, K; Udagawa, S; Lu, SQ; Shimabukuro, A; Takemura, A

  FRONTIERS IN MARINE SCIENCE ( Frontiers in Marine Science )  12   2025.06 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Introduction Environmental factors, including light and salinity, influence fish growth. It has been hypothesized that optimizing environmental factors can activate the endocrine system and enhance the growth performance of fish. The aim of the present study was to understand how environmental factors affect the growth performance of juveniles of the Malabar grouper, Epinephelus malabaricus, a valuable species in Asian markets. The combined effects of light wavelength and salinity on growth performance were closely evaluated because each of them had a positive effect on growth stimulation in this species. Methods Juvenile Malabar groupers were reared under combined conditions of blue LED light (BL, 463 nm) and red LED light (RL, 623 nm) at low salinity (LS, 11psu) and high salinity (HS, 34 psu) for two weeks. Biometric parameters were quantified, and related gene expressions were analyzed via qPCR. Results Specific growth rate (SGR) was significantly higher in fish under BL/LS, followed by RL/LS and BL/HS. A higher condition factor (CF) was observed in fish under BL/LS, whereas a lower food conversion rate (FCR) was observed in fish under BL/LS and RL/LS. The transcript levels of acetyl-CoA carboxylase (acaca) and fatty acid synthase (fas) in the liver increased under BL/LS (vs. RL/LS). BL upregulated neuropeptide Y (npy), but not pro-opiomelanocortin (pomc), in the fish brain under both salinities. Transcript levels of growth hormone (gh) in the pituitary gland and insulin-like growth factor-1 (igf-1) in the liver were significantly lower in fish under BL/LS than in those under BL/HS. Discussion The promotion of growth performance in juvenile Malabar groupers were attributable to the additive effects of light wavelength and salinity. Since we demonstrated the combined effects of blue light and isosmotic salinity on lipogenesis and somatic growth, optimization of light and salinity conditions can enhance the aquaculture productivity of Malabar groupers.

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• Combined effects of light and salinity on the growth performance in juveniles of the Malabar grouper, Epinephelus malabaricus

  Zhu Yafan, Fukunaga Kodai, Udagawa Shingo, Shimabukuro Akimichi, Lu Siqi, Takemura Akihiro

  Frontiers in Marine Science ( Frontiers Media S.A. )  12   1 - 10   2025.06 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

  　View Summary

  Introduction: Environmental factors, including light and salinity, influence fish growth. It has been hypothesized that optimizing environmental factors can activate the endocrine system and enhance the growth performance of fish. The aim of the present study was to understand how environmental factors affect the growth performance of juveniles of the Malabar grouper, Epinephelus malabaricus, a valuable species in Asian markets. The combined effects of light wavelength and salinity on growth performance were closely evaluated because each of them had a positive effect on growth stimulation in this species. Methods: Juvenile Malabar groupers were reared under combined conditions of blue LED light (BL, 463 nm) and red LED light (RL, 623 nm) at low salinity (LS, 11psu) and high salinity (HS, 34 psu) for two weeks. Biometric parameters were quantified, and related gene expressions were analyzed via qPCR. Results: Specific growth rate (SGR) was significantly higher in fish under BL/LS, followed by RL/LS and BL/HS. A higher condition factor (CF) was observed in fish under BL/LS, whereas a lower food conversion rate (FCR) was observed in fish under BL/LS and RL/LS. The transcript levels of acetyl-CoA carboxylase (acaca) and fatty acid synthase (fas) in the liver increased under BL/LS (vs. RL/LS). BL upregulated neuropeptide Y (npy), but not pro-opiomelanocortin (pomc), in the fish brain under both salinities. Transcript levels of growth hormone (gh) in the pituitary gland and insulin-like growth factor-1 (igf-1) in the liver were significantly lower in fish under BL/LS than in those under BL/HS. Discussion: The promotion of growth performance in juvenile Malabar groupers were attributable to the additive effects of light wavelength and salinity. Since we demonstrated the combined effects of blue light and isosmotic salinity on lipogenesis and somatic growth, optimization of light and salinity conditions can enhance the aquaculture productivity of Malabar groupers.

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• Two pathways regulate insulin-like growth factor genes in the brain and liver of the tropical damselfish Chrysiptera cyanea : A possible role for melatonin in the actions of growth and thyroid hormones

  Rizky, D; Byun, JH; Mahardini, A; Fukunaga, K; Udagawa, S; Pringgenies, D; Takemura, A

  COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY ( Comparative Biochemistry and Physiology Part A Molecular and Integrative Physiology )  296   111679   2024.10 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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• Effects of dopamine and melatonin treatment on the expression of the genes associated with artificially induced sexual maturation in Japanese eel, <i>Anguilla japonica</i>

  Byun, JH; Hyeon, JY; Hettiarachchi, SA; Udagawa, S; Mahardini, A; Kim, JM; Hur, SP; Takemura, A

  JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY ( Journal of Experimental Zoology Part A Ecological and Integrative Physiology )  341 ( 4 ) 389 - 399   2024.05 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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Other Papers 【 display / non-display 】

Other Papers 【 display / non-display 】

• Effect of light wavelength on growth performance, photoreceptor expression and neuroendocrine system of Malabar grouper Epinephelus malabaricus

  ZHU Yafan, 宇田川伸吾, 福永耕大, 島袋亮道, 竹村明洋

  日本水産学会大会講演要旨集(CD-ROM)   2022   2022

   

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Presentations 【 display / non-display 】

Presentations 【 display / non-display 】

• Environmental Impact Assessment of Japanese Aquaculture: A Case Study of Malabar Grouper Production Using LCA

  Tetsuya Ishida, Shingo Udagawa, Yuki Sato, Akimichi Shimabukuro, Satoshi Ohara, Akihiro Takemura, Yasunori Kikuchi

  International Conference on Industrial Ecology 2025  2025.06  -  2025.07 

• Relationship Between Moonlight and Coral Reef Organisms in Okinawa

  Shingo Udagawa

  Asia Pacific Network  2022.11  -  2022.11 

• Effect of light wavelength on growth performance, photoreceptor expression and neuroendocrine system of Malabar grouper Epinephelus malabaricus

  2022.09  -  2022.09 

• SELECTED WAVELENGTHS OF LIGHT STIMULATE THE GROWTH ENDOCRINE AXIS IN THE MALABAR GROUPER

  Yafan Zhu, Kodai Fukunaga, Shingo Udagawa, Akimichi Shimabukuro, Akihiro Takemura

  14th International conference on the biology fish  2022.06  -  2022.06 

• Tidal-related changes in hydrostatic pressure alter gene expression in the brain of a tropical wrasse

  Shingo Udagawa, Hiroyuki Toguchi, Yuki Takeuchi, Hiroki Takekata, Akihiro Takemura

  10th International Congress of Comparative Phisiology and Biochemistry Mechanisms and evolutionary processes  2019.08  -  2019.08 

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Academic Awards 【 display / non-display 】

Academic Awards 【 display / non-display 】

• Best Poster Award at the 28th Annual Meeting of the Japanese Society for Chronobiology

  2021.11   Japanese Society for Chronobiology   Elucidation of the water pressure transduction in threespot wrasse

  Winner: Shingo Udagawa, Hiroki Takekata, Yuk Takeuchii, Akihiro Takemura

Grant-in-Aid for Scientific Research 【 display / non-display 】

Grant-in-Aid for Scientific Research 【 display / non-display 】

• Grant-in-Aid for Scientific Research(B)

  Project Year: 2024.04  -  2027.03 

  Direct: 14,200,000 (YEN)  Overheads: 18,460,000 (YEN)  Total: 4,260,000 (YEN)

• The water pressure perception in fresh-water fish: mechanisms and consequences

  Grant-in-Aid for Young Scientists

  Project Year: 2023.04  -  2026.03 

  Direct: 3,600,000 (YEN)  Overheads: 4,680,000 (YEN)  Total: 1,080,000 (YEN)

• Elucidation of the water pressure transduction in fish

  Grant-in-Aid for JSPS Fellows

  Project Year: 2019.04  -  2021.03 

  Direct: 2,100,000 (YEN)  Overheads: 2,100,000 (YEN)  Total: 0 (YEN)