1991 Fiscal Year Final Research Report Summary
Bioscientic Studies on the Seaward and Spawning Migration of Salmonids in the North Pacific Ocean
Grant-in-Aid for General Scientific Research (A)
|Allocation Type||Single-year Grants |
|Research Institution||Hokkaido University |
HATANO Mutsuo Hokkaido University, Faculty of Fisheries, Professor, 水産学部, 教授 (80001600)
SATO Osamu Hokkaido University, Faculty of Fisheries, Emeritus Professor, 水産学部, 名誉教授 (70001568)
TAKAHASHI Koretaro Hokkaido University, Faculty of fisheries, Associate Professor, 水産学部, 助教授 (90125328)
HARA Akihiko Hokkaido University, Faculty of fisheries, Associate Professor, 水産学部, 助教授 (40091483)
YAMAUCI Kohei Hokkaido University, Faculty of fisheries, Associate Professor, 水産学部, 助教授 (10109514)
YAMADA Juro Hokkaido University, Faculty of Fisheries, Professor, 水産学部, 教授 (60001575)
|Project Period (FY)
1989 – 1991
|Keywords||Salmonid fishes / Spawning migration / Sexual maturation / Biochemical changes / Quality assessment / Thyroid gland hormone / Sex steroid hormones / Fish behavior|
Pacific salmon are typically anadromous fish, developing in the ocean and spawning in the fresh water. This biological feature governs the pattern of changes in their hormone levels and their chemical compositions. The purpose of this study was to elucidate the physiological changes as well as the degenerative changes occur during migration. Results obtained were as follows.
Physiological changes (1)It was suggested that in salmonids including chum salmon, serum estradiol-17beta plays a major role in vitellogenesis, and 17alpha, 20beta-hydroxy-4-pregnen-3-one has an important role in final oocyte maturation.
(2)11-ketotestosterone and 17alph, 20beta-dihydroxy-4-pregnen-3-one respectively are the major steroids responsible for latter phase of spermatogenesis and spermiation in male chum salmon.
(3)Gill and kidney were considered to be involved in ion regulation during smoltification.
(4)Thyroxine plays a role on physiological characteristics in smolting.
(5)Two throxine deiodination pathways were borne out in some salmonids.
(6)A peculiar IgM-like protein was found in egg yolk of chum salmon, having a lower molecular weight than that of serum IgM, consists of H chain of smaller molecular weight as well as H and L chain of ordinary molecular weight.
Quality Assessment (7)The degenerative changes in muscle such as decrease in total lipid and in protein contents accompanied by sexually full maturation were attributed to not only the progressed activation of lipid hydrolytic enzymes as well as autolytic activity, but also the inactivation of lipid and protein syntheses that occur both in muscle and in liver tissues.
(8)Extraordinary emulsifying ability of spawning fish muscle was attributed to the high level of protease activity in the muscle
(9)Hunter "a" value was concluded to be the most reliable index for quality assesment of late run chum salmon as well as sockeye salmon
Research Products (13results)