Puget Sound Chum Salmon Growth Linked to Competitor Abundance, Climate Indices, and Copepod Species Richness

Author(s):  
Austin J. Anderson ◽  
Andrew M. Claiborne ◽  
Mickey Agha ◽  
Marisa N. C. Litz
1998 ◽  
Vol 15 (1-4) ◽  
pp. 185-206 ◽  
Author(s):  
André Raibaut ◽  
Claude Combes ◽  
Françoise Benoit

1975 ◽  
Vol 32 (8) ◽  
pp. 1419-1429 ◽  
Author(s):  
Robert J. Feller ◽  
Victor W. Kaczynski

Analysis of gut contents shows that juvenile (30–50 mm) chum salmon (Oncorhynchus keta) in Puget Sound select epibenthic organisms as their primary prey. Harpacticoid copepods numerically comprised over 80% of their natural diet in two areas studied, while terrestrial insects and cladocerans were most important in a third area. Calculation of Ivlev (1961) electivity coefficients indicated high selectivity factors for harpacticoids at one site (+0.59 to +0.94). Comparison of fish gut contents with quantitative epibenthic pump samples of available prey shows that prey selection was size related, but opposite that currently reported in the literature (e.g. Brooks and Dodson 1965); that is, the smaller of the available prey was preferred. This was true for both the total available prey size spectrum and the harpacticoid copepod fraction of the prey spectrum. Large numbers of prey eaten per fish suggest that juvenile chum salmon may exert high predation pressure on nearshore epibenthic organisms in Puget Sound during spring.


1983 ◽  
Vol 40 (4) ◽  
pp. 426-435 ◽  
Author(s):  
Nicholas J. Bax

The average daily loss in numbers from a group of fluorescently marked, hatchery-reared, juvenile chum salmon (Oncorhynchus keta) remaining in the nearshore zone following their release from the hatchery into southern Hood Canal, Washington State, was estimated at 38–49%. This estimated loss was then adjusted by the estimated maximum emigration of marked fish from the sampling area and the average daily mortality over a 2- and a 4-d time period estimated at between 31 and 46%. These estimates are an order of magnitude higher than estimates of the average daily mortality of naturally emigrating juvenile pink salmon (O. gorbuscha) from the Bella Coola River, British Columbia, over a 40-d time period (Parker 1968). The two studies are contrasted and it is suggested that daily mortality is highly variable over the 40 d subsequent to saltwater entry, with mortality higher initially, particularly for those fish remaining close to their point of saltwater entry.


<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.


1973 ◽  
Vol 30 (7) ◽  
pp. 1003-1008 ◽  
Author(s):  
V. W. Kaczynski ◽  
R. J. Feller ◽  
J. Clayton ◽  
R. J. Gerke

Pink and chum salmon (Oncorhynchus gorbuscha and O. keta) fry and Clarke–Bumpus plankton tows were collected from three beach areas in Puget Sound in spring 1970. Chum fry and benthic pump samples were taken in 1971. The diets of the young of the two species were similar. Epibenthic harpacticoid copepods were the chief prey of the chum and pink salmon (57 and 36%, respectively, in 1970). Distinct differences were apparent, the more notable being the preference for invertebrate eggs exhibited by the pinks and the higher preferences for small gammarid amphipods and harpacticoids exhibited by the chums. The stomach contents showed no resemblance to the plankton hauls taken in the same area. The onshore stage of development appears to be a distinct ecological stage in the life cycles of these species.


2014 ◽  
Vol 65 (8) ◽  
pp. 727 ◽  
Author(s):  
Gilmar Perbiche-Neves ◽  
Geoffrey A. Boxshall ◽  
Marcos G. Nogueira ◽  
Carlos E. F. da Rocha

Copepod assemblages were analysed across La Plata River basin, the second largest in South America. High values of species richness and Shannon–Wiener diversity were found in the lower Paraná River, the main and largest river of the basin, and in eutrophic reservoirs located in the upper basin. The species richness was negatively correlated with turbidity, probably because of the negative impact on filtration rates in calanoids. There was a trend of decreasing richness correlated with high water flow in reservoirs with short water-retention time (<40 days) and simple morphometric shape, and also in deeper oligo-mesotrophic reservoirs with very long water-retention time and dendritic shape (variables that occurred in combination in the present study). The number of copepod species (46) found in our study is only about half of the gamma diversity estimated using Jack1 non-parametric analysis for the basin (86 species). There are groups of copepod species typical of reservoirs and rivers, and others that can occur in both of these habitat types. Reservoir and lentic species are favoured by a deeper water column, higher temperatures and higher transparency, whereas the opposite is the case of typical riverine species. There is also a group of species that occur in both sets of conditions.


1989 ◽  
Vol 46 (7) ◽  
pp. 1147-1153 ◽  
Author(s):  
Brian Bigler

A recently documented scale characteristic of chum salmon (Oncorhynchus keta) originating from Hokkaido, Japan, has been found distributed almost exclusively among stocks of Asian origin. Scales from 10 544 chum salmon collected from 25 near-shore locations throughout the North Pacific Ocean were examined. Resorption of the scale focus, including instances where an easily visible hole had been formed, was found among 10.8% of Japanese chum salmon and 15.9% of chum salmon originating from the Soviet Union. In North America, this trait was infrequent (< 0.5%) among populations north of the Aleutian Islands, British Columbia, and Puget Sound, and was not found in Cook Inlet, Prince William Sound, and Southeast Alaska. Focal scale resorption arises from osteoclastic cellular activity, most likely following the first winter of life, and remains as a permanent mark thereafter. This unique, uniformly occurring, easily identifiable scale characteristic will provide a valuable tool for stock identification. Evidence of focal scale resorption is also reported in sockeye (O. nerka), coho (O. kisutch), and king salmon (O. tshawytscha), but was not found in pink salmon (O. gorbuscha), sampled from locations in Alaska.


2019 ◽  
pp. 120-125
Author(s):  
Marisa Litz ◽  
Aaron Dufault ◽  
Andrew Claiborne ◽  
James Losee ◽  
Tyler Garber

Author(s):  
Mickey Agha ◽  
James P. Losee ◽  
Marisa N. C. Litz ◽  
Craig Smith ◽  
Jason J. Schaffler ◽  
...  

Understanding and quantifying migration phenology of commercially harvested Pacific salmon (Oncorhynchus spp.) is a cornerstone for managing sustainable populations. Here, we use a multi-decadal data timeseries together with a hypothesis driven framework to evaluate migration phenology in adult fall and winter ecotype chum salmon (O. keta) in a poorly studied but highly managed system – the South Puget Sound (SPS) of Washington State, USA. Using generalized additive mixed models that accounted for temporal autoregressive dynamics, we examined the effect of commercial harvest, climate variation, intraspecific density dependence, and predator buffering on migration timing and run duration. SPS chum salmon are migrating earlier over time, especially the winter ecotype that showed the strongest temporal shift from historical timing. Migration timing shifts were closely associated with regional-scale marine climate regimes, local-scale freshwater availability, and statewide pinniped abundance. In conclusion, there is potential for the winter ecotype migration converging with that of the fall ecotype, and that directional change in migration phenology may be driven by a unique combination of ecosystem factors.


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