Anatomical specialization in the gut of Pacific salmon (Oncorhynchus): evidence for oceanic limits to salmon production?

1997 ◽  
Vol 75 (6) ◽  
pp. 936-942 ◽  
Author(s):  
D. W. Welch
Keyword(s):  
Carrying Capacity ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Gelatinous Zooplankton ◽  
Oncorhynchus Keta ◽  
Evolutionary Selection ◽  
The North ◽  
Salmon Production ◽  
The North Pacific ◽  
Trophic Competition

The stomach (but not the intestine) of chum salmon (Oncorhynchus keta) is greatly enlarged relative to that of other species of Pacific salmon. This permits the exploitation of gelatinous zooplankton (jellyfish, ctenophores, and salps), an abundant but low-energy prey unused by other species of salmon, as a major food source. The unique gut structure of chum salmon therefore allows efficient feeding on a little-exploited branch of the food web and reduces interspecific trophic competition. The development of this remarkable anatomical specialization suggests that salmon abundances were previously high enough that the resulting trophic competition led to evolutionary selection to reduce trophic competition. As total salmon abundances in the North Pacific are now probably the highest of this century, the carrying capacity of the ocean rather than that of fresh water could limit overall salmon production if abundances are once again approaching pre-exploitation levels.

scholarly journals Sea to sky: impacts of residual salmon-derived nutrients on estuarine breeding bird communities

2011 ◽  
Vol 278 (1721) ◽  
pp. 3081-3088 ◽  
Author(s):  
Rachel D. Field ◽  
John D. Reynolds
Keyword(s):  
Pacific Salmon ◽  
Bird Communities ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Breeding Bird ◽  
The North ◽  
Bird Density ◽  
Post Spawning ◽  
The North Pacific ◽  
Forest Habitats

Pacific salmon ( Oncorhynchus spp.) returning to streams around the North Pacific Rim provide a nutrient subsidy to these ecosystems. While many species of animals feed directly on salmon carcasses each autumn, salmon-derived nutrients can also be stored in coastal habitats throughout the year. The effects of this storage legacy on vertebrates in other seasons are not well understood, especially in estuaries, which can receive a large portion of post-spawning salmon nutrients. We examine the effects of residual salmon-derived nutrients, forest habitats and landscape features on summer breeding birds in estuary forests. We compared models containing environmental variables and combined chum ( Oncorhynchus keta ) and pink ( Oncorhynchus gorbuscha ) salmon biomass to test predictions concerning bird density and diversity. We discovered that total bird, insectivore, golden-crowned kinglet and Pacific wren densities and Shannon's diversity in the summer were strongly predicted by salmon biomass in the autumn. For most metrics, this relationship approaches an asymptote beyond 40 000 kg of salmon biomass. Foliage height diversity, watershed catchment area and estuary area were also important predictors of avian communities. Our study suggests that the legacy of salmon nutrients influences breeding bird density and diversity in estuaries that vary across a wide gradient of spawning salmon biomass.

Population Structure and Identification of North Pacific Ocean Chum Salmon (Oncorhynchus keta) Revealed by an Analysis of Minisateliite DNA Variation

1994 ◽  
Vol 51 (6) ◽  
pp. 1430-1442 ◽  
Author(s):  
Eric B. Taylor ◽  
Terry D. Beacham ◽  
Masahide Kaeriyama
Keyword(s):  
Population Structure ◽  
Pacific Ocean ◽  
North Pacific ◽  
Chum Salmon ◽  
North Pacific Ocean ◽  
Oncorhynchus Keta ◽  
The North ◽  
Yukon River ◽  
Regional Population ◽  
The North Pacific

We examined geographic variability in minisatellite DNA in chum salmon (Oncorhynchus keta) from 42 populations from the North Pacific Ocean to (1) determine the extent of regional population structure at minisatellite loci and (2) assess the ability of minisatellite variability to determine the geographic origin in individual chum salmon. Restriction fragments from 1.6 to 13.6 kilobase pairs in molecular weight were resolved with a minisatellite probe. The fragments were inherited from parent to offspring and appeared to represent segregation at two linked loci. Minisateliite DNA variability was negligible between annual samples from the same rivers, and chum salmon fell into three regional population groupings: (i) Japanese, (ii) Russian/Yukon River, and (iii) southeastern Alaska/British Columbia salmon. These regional groupings probably reflect historical patterns of postglacial dispersal of chum salmon from three distinct refugia in the North Pacific. We used restriction fragment counts as input to linear discriminant and neural network classification of independent test samples of salmon. Accuracies of 90–95, 81–86, and 72–80% were achieved when classifying fish as of either Japan/Russia/Yukon River versus southeastern Alaska/British Columbia origin, Japan versus Russia/Yukon River origin, or Russia versus Yukon River origin, respectively.

scholarly journals Genetic Identification of the North Pacific Chum Salmon (Oncorhynchus keta) Stocks

2003 ◽  
Vol 36 (6) ◽  
pp. 578-585
Author(s):  
Woongsic JUNG ◽  
Youn-Ho LEE ◽  
Suam KIM ◽  
Deuk-Hee JIN ◽  
Ki Baek SEONG
Keyword(s):  
North Pacific ◽  
Chum Salmon ◽  
Genetic Identification ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
The North ◽  
The North Pacific

Recent Changes in Age and Size of Chum Salmon (Oncorhynchus keta) in the North Pacific Ocean and Possible Causes

1993 ◽  
Vol 50 (2) ◽  
pp. 290-295 ◽  
Author(s):  
Yukimasa Ishida ◽  
Soto-o Ito ◽  
Masahide Kaeriyama ◽  
Skip McKinnell ◽  
Kazuya Nagasawa
Keyword(s):  
Body Weight ◽  
Pacific Ocean ◽  
North Pacific ◽  
Chum Salmon ◽  
North Pacific Ocean ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
The North ◽  
Mean Width ◽  
The North Pacific

Changes in age composition and size of adult chum salmon (Oncorhynchus keta) from rivers in Japan, Russia, and Canada were examined based on body weight and scale measurement data collected from 1953 to 1988. A significant increase in mean age was found in Japanese and Russian stocks after 1970 when the number of Japanese chum salmon began to increase exponentially, but not in the Canadian stock. Significant decreases in mean body weight, mean scale radius, and mean width of the third-year zones of age 4 chum salmon also occurred in Japanese and Russian stocks after 1970. Based on the Japanese salmon research vessel data from 1972 to 1988, significant negative relationships between catch-per-unit-effort and mean body weight of chum salmon were observed in summer in the central North Pacific Ocean where the distribution of Japanese and Russian stocks overlaps. These results suggest that density dependence is one of the possible causes for the recent changes in age and size of chum salmon in the North Pacific Ocean.

Consumption and distribution of salmon (Oncorhynchus spp.) nutrients and energy by terrestrial flies

2006 ◽  
Vol 63 (9) ◽  
pp. 2076-2086 ◽  
Author(s):  
Morgan D Hocking ◽  
Thomas E Reimchen
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Isotope Analysis ◽  
Terrestrial Ecosystems ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
The North ◽  
Terrestrial Habitats ◽  
Salmon Carcasses

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.

Mechanism and Occurrence of Focal Scale Resorption among Chum Salmon (Oncorhynchus keta) of the North Pacific Ocean

1989 ◽  
Vol 46 (7) ◽  
pp. 1147-1153 ◽  
Author(s):  
Brian Bigler
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Chum Salmon ◽  
North Pacific Ocean ◽  
Puget Sound ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
The North ◽  
Scale Characteristic ◽  
The North Pacific

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.

Change in the Known Ocean Distribution of Japanese Chum Salmon, Oncorhynchus keta, in Relation to the Progress of Stock Enhancement

1994 ◽  
Vol 51 (3) ◽  
pp. 501-505 ◽  
Author(s):  
Miki Ogura ◽  
Soto-o Ito
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Chum Salmon ◽  
North Pacific Ocean ◽  
Stock Enhancement ◽  
Distribution Area ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
The North ◽  
The North Pacific

New information on the ocean distribution of maturing Japanese chum salmon, Oncorhynchus keta, based on offshore tagging experiments conducted from 1956 to 1991 is summarized. Of 138 039 chum released in the North Pacific Ocean and its adjacent seas, 663 fish were recovered along the Japanese coast in the year of tagging and up to March of the next year. The distribution area of maturing Japanese chum indicated by these tag recoveries extended much further south and west than shown in previous studies. The central and western North Pacific Ocean now form important parts of the range. We conclude that extensive stock enhancement of chum in Japan is associated with enlargement of the known distribution area of maturing Japanese chum in the North Pacific Ocean.

Orientation of Chum Salmon (Oncorhynchus keta) After Internal and External Magnetic Field Alteration

1983 ◽  
Vol 40 (10) ◽  
pp. 1598-1606 ◽  
Author(s):  
T. P. Quinn ◽  
C. Groot
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Chum Salmon ◽  
North Pacific Ocean ◽  
Oncorhynchus Keta ◽  
Chum Salmon Oncorhynchus Keta ◽  
The North ◽  
Juvenile Chum Salmon ◽  
The North Pacific ◽  
Coded Wire Tags

Groups of hatchery reared juvenile chum salmon (Oncorhynchus keta) from Conuma River, British Columbia, were tested for compass directional preferences in experimental tanks. Chum salmon generally moved in the direction appropriate for migration through Nootka Sound to the North Pacific Ocean. Fry orientation was not disrupted by covers over the tanks. Stainless steel coded wire tags inserted into the heads of the salmon had little effect, regardless of whether they were magnetized or not. A 90° change in the external magnetic field influenced fry directional movements, but the magnitude and direction of the change were not readily explainable.

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