| 翻訳と辞書 |
| Pre-spawn mortality in coho salmon ： ウィキペディア英語版 |
Pre-spawn mortality in coho salmon
Pre-spawn mortality is a phenomenon where adult coho salmon, ''Oncorhynchus kisutch'', die before spawning when returning to freshwater streams to spawn.〔Feist BE, Buhle ER, Arnold P, Davis JW, and Scholz NL. 2011. Landscape ecotoxicology of Coho salmon spawner mortality in urban streams. ''PLOS ONE'' 6(8): 1-11.〕〔Spromberg JA, and Scholz NL. 2011. Estimating the future decline of wild Coho salmon populations resulting from early spawner die-offs in urbanizing watersheds of the Pacific Northwest, USA. ''Integrated Environmental Assessment and Management'' 9999: 1-9.〕 This occurrence has been observed in much of the Puget Sound region of the Pacific Northwest.〔McCarthy SG, Incardona JP, and Scholz NL. 2008. Coastal storms, toxic runoff, and the sustainable conservation of fish and fisheries. ''American Fisheries Society Symposium'' 64: 1-21.〕 During fall migration, salmonids (trout and salmon) pass through urban watersheds which are contaminated with stormwater runoff.〔 As the coho salmon pass through these waters, many will show symptoms of lethargy, loss of equilibrium and disorientation, and die within a few hours of showing these symptoms.〔〔 These symptoms and behaviors are prevalent after rain events.〔 Mortality often occurs before salmon have the opportunity to spawn, which is determined by cutting open female carcasses and observing for unfertilized eggs.〔 Rates of pre-spawn mortality could impact the local salmon populations.〔 Based on model projections, if rates continue, populations of coho salmon could become extinct within the next few decades.〔
Weight of evidence suggests coho salmon pre-spawn mortality is due to exposure to stormwater runoff, although the exact contaminant or mixture that is responsible remains unknown.〔Scholz NL, Myers MS, McCarthy SG, Labenia JS, McIntyre JK, Ylitalo GM, Rhodes LD, Laetz CA, Stehr CM, French BL, McMillan B, Wilson D, Reed L, Lynch KD, Damm S, Davis JW, and Collier TK. 2011. Recurrent die-offs of adult Coho salmon returning to spawn in Puget Sound lowland urban streams. ''PLOS ONE'' 6(12): 1-12.〕 A negative correlation exists between the incidence of pre-spawn mortality and urban land use, specifically with the impervious surfaces, commercial property type, and local roads.〔〔 Exposure to metals and petroleum hydrocarbons displayed some response to pre-spawn mortality, while exposure to pesticides, diseases, and water quality variables did not elicit this effect.〔 This trend has not been observed in any other life history stage of the coho salmon nor in other salmon species in the Puget Sound region.〔
== History ==
Pre-spawn mortality was first observed in the Puget Sound after efforts had gone into restoring urban watersheds in hopes of drawing salmon back to these areas. Restoration consisted of removing culverts, debris, and any other barriers.〔NOAA Coastal Storm Programs. Available online at: (Stormwater and Salmon- Pre-spawn Mortality of Coho Salmon in Restored Urban Streams ) Accessed on 4 May 2013.〕〔Katz SL, Barnas K, Hicks R, Cowen J, and Jenkinson R. 2007. Freshwater habitat restoration actions in the Pacific Northwest: a decade’s investment in habitat improvement. ''Restoration Ecology'' 15(3): 494-505.〕 Restoration projects were successful in that salmon returned to these runs, however, in initial surveys of restoration success, the pre-spawn mortality symptoms were observed.〔 It is now recognized that in restoring watersheds, water quality and contamination must also be considered for successful spawning events of coho salmon if the population is to persist.〔
Upon displaying specific symptoms (below), mortality of the coho salmon can be expected within a few hours. Mortality usually occurs before these fish have had a chance to spawn. In fact, in observing the female coho salmon carcasses, most of the fish have retained greater than 90 percent of their eggs.〔 Pre-spawn mortality occurs in both male and female salmon, however, it is difficult to determine if male salmon have spawned, thus, pre-spawn mortality is usually signified by egg retention of female salmon.〔 Pre-spawn mortality has also been observed in both wild and hatchery fish alike.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Pre-spawn mortality in coho salmon」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|