Growth and survival rate of the Four-spine Sculpin, Cottus kazika, reared in different environmental salinities.

Iwatani, Hozi; Watari, Tomomi; Inoue, Koji; Takei, Yoshiyuki

doi:10.2331/suisan.69.52

Cited by 2 publications

(3 citation statements)

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“…13 These results suggest that the major habitat of larvae greater than 17.5 mm TL or older than 80 days of age is in a FW area under natural conditions. However, Iwatani et al 5 demonstrated that the larvae over such age and size still exhibit higher rates of survival and growth in SW than in FW. This somewhat paradoxical result was also reproduced in this study (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The natural population of C. kazika has decreased in recent years 4 and, therefore, various efforts have been made to establish an efficient culture system for this species 3,5 . Among such attempts, we found recently, by rearing experiments in the laboratory, that larvae older than the stage of migration to the river grow faster in seawater (SW) than in fresh water (FW) 5 . This result suggests a relationship between hypoosmoregulation and growth.…”

Section: Introductionmentioning

confidence: 99%

“…3,5 Among such attempts, we found recently, by rearing experiments in the laboratory, that larvae older than the stage of migration to the river grow faster in seawater (SW) than in fresh water (FW). 5 This result suggests a relationship between hypoosmoregulation and growth. In salmonid fishes, it has been shown that the growth is accelerated during SW adaptation, which is mediated by increased expression of growth hormone (GH) and insulin-like growth factor I (IGF-I).…”

Section: Introductionmentioning

confidence: 99%

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Expression of insulin-like growth factor I gene is involved in enhanced growth of juvenile four-spine sculpin Cottus kazika in seawater

Iwatani¹,

Inoue

Takei

2005

Fisheries Sci

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To study the mechanism of faster growth of the sculpin Cottus kazika in seawater (SW) than in fresh water (FW), we transferred 120-day-old juveniles from FW to SW, 1/3 SW or FW, and survival, growth and levels of transcripts of growth hormone (GH) gene in the pituitary and insulin-like growth factor I (IGF-I) gene in the liver were examined 20 and 40 days after transfer. The survival rates of fish reared in SW and 1/3 SW were higher than the FW controls. The growth was fastest in SW and slowest in the controls. IGF-I gene transcripts increased in SW-reared fish 40 days after transfer compared with the controls, while GH gene transcripts did not. Juveniles of 1 year of age were transferred from FW to SW or 1/3 SW, and GH and IGF-I gene transcripts were compared after 48 h. In this shortterm experiment, the level of GH gene transcripts was higher in fish reared in SW and 1/3 SW, while no difference was found in the IGF-I gene transcripts. Thus, the GH gene transcripts increased only transiently after SW transfer but the IGF-I gene transcripts increased gradually for 40 days, suggesting that the long-term increase in IGF-I gene expression is involved in the enhanced growth in SW and GH may play an initiation role for growth enhancement.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%