Current status of natural spawning of chum salmon Oncorhynchus keta in rivers with or without hatchery stocking on the Japan Sea side of northern Honshu, Japan

Information on the status of natural spawning is needed on the Japan Sea side of northern Honshu, Japan for ecosystem-based sustainable management of chum salmon resources. We conducted on-site visual surveys in October–December of 2015 and 2016 that targeted spawning chum salmon redds in all rivers...

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Bibliographic Details
Published in:Fisheries science 2018-05, Vol.84 (3), p.453-459
Main Authors: Iida, Masaya, Yoshino, Kunimasa, Katayama, Satoshi
Format: Article
Language:English
Subjects:
Biomedical and Life Sciences
Ecosystem management
Fish
Fish & Wildlife Biology & Management
Fish conservation
Fish hatcheries
Food Science
Freshwater & Marine Ecology
Freshwater fishes
Life Sciences
Oncorhynchus keta
Original Article
Ponds
Redds
Reproduction
Resource management
Rivers
Salmon
Spawning
Stocking
Surveys
Sustainability management
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Summary:Information on the status of natural spawning is needed on the Japan Sea side of northern Honshu, Japan for ecosystem-based sustainable management of chum salmon resources. We conducted on-site visual surveys in October–December of 2015 and 2016 that targeted spawning chum salmon redds in all rivers > 5 km long (total 94 rivers) in Akita, Yamagata, Niigata (including Sado Island), and Toyama prefectures. The ratio of rivers found to host natural reproduction to the total number of surveyed rivers was 93.6% (44/47) in stocked rivers and 74.5% (35/47) in non-stocked rivers. These results show that there is a wide occurrence of natural reproduction of chum salmon in these rivers, regardless of the history of hatchery stocking. The density of spawning redds (number of redds/1000 m 2 ) as an indicator of chum salmon escapements did not differ ( P  = 0.54) between stocked rivers (mean 3.5, N   = 49) and non-stocked rivers (mean 2.4, N  = 36),when rivers where no redds were observed were excluded from the analysis. These results suggest that chum salmon escapements into non-stocked rivers may not be negligible. Conservation measures for wild fish are needed in stocked and non-stocked rivers to promote enhancement programs based on natural reproduction.
ISSN:0919-9268
1444-2906
DOI:10.1007/s12562-018-1192-7