Lacustrine forms of mature male masu salmon,oncorhynchus masou brevoort, in lake toya, hokkaido, japan

2000 ◽  
Vol 47 (3-4) ◽  
pp. 407-410 ◽  
Author(s):  
Toshiaki Yamamoto ◽  
Kaneaki Edo ◽  
Hiroshi Ueda
Keyword(s):  
Masu Salmon ◽  
Mature Male ◽  
Oncorhynchus Masou ◽  
Lake Toya ◽  
Masu Salmon Oncorhynchus Masou

Life History Forms of Male Masu Salmon (Oncorhynchus masou) in South Primor'e, Russia

1994 ◽  
Vol 51 (1) ◽  
pp. 197-208 ◽  
Author(s):  
V. V. Tsiger ◽  
V. I. Skirin ◽  
N. I. Krupyanko ◽  
K. A. Kashkin ◽  
A. Yu. Semenchenko
Keyword(s):  
Life History ◽  
Masu Salmon ◽  
Early Summer ◽  
Mature Male ◽  
Oncorhynchus Masou ◽  
Ordinary Life ◽  
Marine Life ◽  
Mature Male Parr ◽  
Masu Salmon Oncorhynchus Masou

In South Primor'e (Russia), mature male masu salmon (Oncorhynchus masou) parr are found at age 0 + to 3 + (9–22 cm). After first maturation, some male parr die, while others survive and mature the following year. Immature males become smolts after one or two winters in rivers and migrate to the sea in spring–early summer. After one winter in the sea, they return as sea-run normal-sized (40–70 cm) males at age R.1 +. Besides mature male parr and normal-sized sea-run males, jacks (28–33 cm) at age R.0 + were found. Such males return to rivers after some months of marine life and do not overwinter in the sea. Some jacks previously spawned as parr, while others did not. All jacks and normal-sized sea-run males die after spawning. Thus, male masu salmon mature as one of four life history forms: (1) male parr, (2) jacks that matured previously as parr, (3) jacks that did not mature previously as parr, and (4) ordinary sea-run males. While mature male parr and sea-run males are ordinary life history forms, both forms of jack are rare.

Effects of timing of nest entry and body size on the fertilization success of alternative male reproductive phenotypes of masu salmon (Oncorhynchus masou)

2008 ◽  
Vol 86 (10) ◽  
pp. 1121-1130 ◽  
Author(s):  
M. Watanabe ◽  
S. Takamura ◽  
K. Maekawa
Keyword(s):  
Body Size ◽  
Parentage Analysis ◽  
Fertilization Success ◽  
Masu Salmon ◽  
Mature Male ◽  
Alternative Mating Tactics ◽  
Oncorhynchus Masou ◽  
Mating Tactics ◽  
Mature Male Parr ◽  
Masu Salmon Oncorhynchus Masou

Using a natural population of masu salmon ( Oncorhynchus masou (Brevoort, 1856)) in a stream of Shikaribetsu Lake, Hokkaido, Japan, we combined behavioural observations with genetic parentage analysis to explore the factors affecting fertilization success achieved by alternative mating tactics (fighting by large migratory males and sneaking by small mature male parr). Larger males gained priority access to females; migrant males do this by holding a guarding position near the nesting female and mature male parr do this by adopting sneaker behaviour and attending spawning groups. Status of mature male parr was related to success of nest entry but not to timing of nest entry, although the timing of nest entry influenced fertilization success of sneakers and ejaculation simultaneous with pair spawning was needed for fertilization by sneakers. The relative body size of each male who successfully spawned with a female is also likely to determine the proportion of eggs he fertilized because larger males have larger ejaculate. These results provide insight into factors relating to variation in fertilization success, how body size dimorphisms may be related to fitness, and evolution of alternative mating tactics.

Changes of serum growth hormone and vitellogenin levels during vitellogenesis in female masu salmon Oncorhynchus masou

2000 ◽  
Vol 66 (4) ◽  
pp. 789-791 ◽  
Author(s):  
Haruhisa Fukada ◽  
Naoshi Hiramatsu ◽  
Makiko Kitamura ◽  
Munetaka Shimizu ◽  
Akihiko Hara
Keyword(s):  
Growth Hormone ◽  
Masu Salmon ◽  
Oncorhynchus Masou ◽  
Serum Growth Hormone ◽  
Masu Salmon Oncorhynchus Masou
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