The current propagation systems and physiological studies of Japanese chum salmon

Ueda, Hiroshi

doi:10.1007/s12562-014-0847-2

Cited by 6 publications

(2 citation statements)

References 53 publications

(50 reference statements)

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“…This application may also be useful for salmon propagation. In Japan, chum salmon is mainly propagated through a hatchery ranching programme that is believed to be one of the most successful fish propagation systems in the world; however, production has decreased in the aftermath of the 2011 Tohoku earthquake and tsunami 31 . Recently, a new embryonic imprinting paradigm for hatchery programme has been introduced in the USA 32 .…”

Section: Discussionmentioning

confidence: 99%

Involvement of hormones in olfactory imprinting and homing in chum salmon

Ueda

Nakamura

et al. 2016

Sci Rep

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The olfactory hypothesis for salmon imprinting and homing to their natal stream is well known, but the endocrine hormonal control mechanisms of olfactory memory formation in juveniles and retrieval in adults remain unclear. In brains of hatchery-reared underyearling juvenile chum salmon (Oncorhynchus keta), thyrotropin-releasing hormone gene expression increased immediately after release from a hatchery into the natal stream, and the expression of the essential NR1 subunit of the N-methyl-D-aspartate receptor increased during downstream migration. Gene expression of salmon gonadotropin-releasing hormone (sGnRH) and NR1 increased in the adult chum salmon brain during homing from the Bering Sea to the natal hatchery. Thyroid hormone treatment in juveniles enhanced NR1 gene activation, and GnRHa treatment in adults improved stream odour discrimination. Olfactory memory formation during juvenile downstream migration and retrieval during adult homing migration of chum salmon might be controlled by endocrine hormones and could be clarified using NR1 as a molecular marker.

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Section: Discussionmentioning

confidence: 99%

Involvement of hormones in olfactory imprinting and homing in chum salmon

Ueda

Nakamura

et al. 2016

Sci Rep

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“…A stock enhancement program for chum salmon Oncorhynchus keta (Walbaum 1792) has been practised in Hokkaido, a prefecture in northern Japan, since 1877 (Kobayashi, ; Ueda, ). A serious problem is high mortality caused by ectoparasitic protozoan infections in O. keta juveniles cultured in freshwater hatcheries.…”

Section: Introductionmentioning

confidence: 99%

Effects of dietary supplementation with oregano essential oil on prevention of the ectoparasitic protozoans Ichthyobodo salmonis and Trichodina truttae in juvenile chum salmon Oncorhynchus keta

Mizuno

Urawa

Miyamoto

et al. 2018

Journal of Fish Biology

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The present study performed three experiments to establish a practical prevention strategy for the ectoparasitic flagellate Ichthyobodo salmonis and ciliate Trichodina truttae in hatchery-reared juvenile chum salmon Oncorhynchus keta using dietary supplementation with oregano essential oil. Experiment 1 showed that a diet supplemented for 3 weeks with 0.02% oregano essential oil significantly prevented infection with I. salmonis and T. truttae in juveniles reared in small tanks. Experiment 2, in outdoor hatchery ponds, demonstrated that the oregano treatment completely prevented I. salmonis infection for 52 days and T. truttae infection for 38 days. Oregano-treated juvenile mortality attributable to infection with these protozoans also decreased to 7.6% of control juvenile mortality, confirming the utility of this treatment in cultured O. keta. Physiological analyses of the oregano-treated juveniles elucidated the treatment's safety in relation to their metabolism, osmoregulation, natural immunity and olfactory responses and also detected carvacrol (a major component of oregano essential oil which shows antimicrobial activity) on the skin. In experiment 3, exposure of the two protozoans to oregano essential oil revealed a weak antiparasitic action on the body surface of the juvenile O. keta. The overall results demonstrate that dietary oregano supplementation is a practical prevention strategy for I. salmonis and T. truttae in hatchery-reared juvenile O. keta and suggest the possibility that its anti-parasitic action is attributable to a component of the oil that emerges onto the skin of the body of the fish.

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