scholarly journals Origin of natural spawning chum salmon estimated from thermal otolith marks of adult salmon carcasses in the Yurappu River, southwestern Hokkaido, Japan

2018 ◽  
Vol 84 (1) ◽  
pp. 133-135
Author(s):  
SHUSUKE UEDA ◽  
TAKASHI ABE ◽  
YOSUKE KOSHINO ◽  
HIDEAKI KUDO

<em>Abstract.</em>—During 1997–2000, chum salmon <em>Oncorhynchus keta </em>spawners and their predators and scavengers were observed in lower Kennedy Creek, a small south Puget Sound, Washington stream. Chum salmon occupy 5.2 km of main Kennedy Creek and a small tributary called Fiscus Creek. Spawning escapements within this stream averaged 39,000 fish annually during this study. Active spawning began in late October and was over by mid- December. Direct consumption of live and dead salmon was observed or inferred from animal signs over the spawning period. Salmon carcasses and tissue fragments could be found scattered along the streambed from October through March, and bones remained year round. Live spawners, carcass flesh, and eggs were consumed by 30 species of birds, mammals, invertebrates, and fungi, including 9 previously undocumented species. High carcass densities allowed selective feeding for some consumers and opportunistic feeding for others. Apparent preferences for eggs by several consumers suggested another important role for naturally spawning salmon. Varied thrush <em>Ixoreus naevius</em>, otter <em>Lutra canadensis</em>, and song sparrow <em>Melospiza melodia </em>showed preferences for salmon eggs, and a cougar <em>Felis concolor </em>killed live salmon and fed on them. Some consumers coordinate successive utilization of carcasses, such as the gull <em>Larus </em>spp., terrestrial beetle <em>Agyrtidae</em>, raccoon <em>Procyon lotor</em>, fly maggots, and mice. Water samples taken from the anadromous areas of these creeks and from the estuary in Totten Inlet showed elevated levels of dissolved ammonium, nitrate, and nitrite. Benefits to chum fry were inferred.


2006 ◽  
Vol 63 (9) ◽  
pp. 2076-2086 ◽  
Author(s):  
Morgan D Hocking ◽  
Thomas E Reimchen

Anadromous Pacific salmon (Oncorhynchus spp.) subsidize terrestrial food webs with their nutrients and carcasses, a process driven largely by selective foraging by bears (Ursus spp.). We quantify wildlife transfer of salmon carcasses to riparian zones on two watersheds in coastal British Columbia and estimate total terrestrial fly production from remnant carcasses. Large-bodied chum salmon (Oncorhynchus keta) were transferred into the forest at a greater rate than were pink salmon (Oncorhynchus gorbuscha) (chum salmon mass = 6089–11 031 kg, 16%–48% of salmon run; pink salmon mass = 2266–2808 kg, 4%–6% of salmon run). Blow flies (genus Calliphora) and other Diptera dominated colonization (>90% of salmon carcasses). Between the two watersheds, 196 and 265 g of Calliphora larvae per metre of spawning length (4 and 7 million larvae for whole watersheds) were generated from salmon carcass transfer. Stable isotope analysis of δ15N and δ13C of spring-emerging adult Calliphora revealed that >80% of individuals had salmon-based signatures. Flies are a dominant consumer and vector of salmon nutrients in terrestrial habitats and supplement the diet of at least 16 vertebrate and 22 invertebrate species. Anticipated further declines of salmon in the North Pacific can be expected to further erode the complex associations coupling marine and terrestrial ecosystems.


Author(s):  
Dave E. Schuett-Hames ◽  
N. Phil Peterson ◽  
Robert Conrad ◽  
Thomas P. Quinn

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