Reproductive Biology of Dolly Varden (Salmonidae)

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The Dolly Varden, Salvelinus malma is widely distributed along the Pacific coast of North America and along the coast from the yule River in Korea to the Anadyr River in the Soviet Union. Hokkaido is the southern limits of their distributions. We compared the genetic variations in the populations between Hokkaido and Alaskan charrs. The Dolly Varden inhabing Hokkaido are land-locked form and no introgression of genes from one population in others is assumed. There were three quite different populations in morphologies and also in zymograms. Nine populations out of 11 clustered at genetic distance less than 0.025. Chihase River and Shikaribesu lake populations differed greatly each other (D=0.126) and also differed from the other nine populations (D=0.030-0.075).On the other hand, the Alaskan populations of S. malma which consist of both the anadromous and river resident forms revealed only small genetic divergence. This suggests that the Alaskan populations have had some gene flow amon … More g the populations. We could captured samples of both Alaskan Arctic charr and Dolly Varden tegether in Karluk lake, Kodiak Island. These fish were visually identified and definitely distinct in morphological characteristics. Zymogram revealed also differences of these sympatric populations. The appearance of Arctic charr-like GPI-1 7 2 patters and of PEP (Ll-1) 85 allele in Karluk Dolly Varden, suggests that there may be some introgression of Arctic charr gene into Dolly Varden in the Karluk lake. This is especially noteworthy because we saw neither of those patterns in other Alaskan Dolly Varden. Many eggs (100-200) of sockye salmon with about 20 gravels per fish were found in the stomach of immature Arctic charr suggesting that they depend their reproductive energy indirectly on the North Pacific productionsThe two different mating tactics are commonly found among mature males of Dolly Varden of sea run form and stream resident form in Alaska. Some males pair directly with females, while others participate in spawning as streakers. Streakers rusk into nest and release sperm at the pair spawnings. Average success in sperm release was 97 % in pairing but only 47 % in streaking, and depended on the distance to the female. The pairing tactic was mostly monopolized by males of primary and secondary dominance rank. These dominant males were the largest (mere than 200 mm in fork length) and the oldest (more than 6 years old) individuals. The mating success of these larger males per season was much higher than that of the smaller and younger males. The detailed reports of this study were edited and published in a single book entitled "Reproductive Biology of Dolly of Varden (Salmonidae) II." Less