scholarly journals River temperature drives salmon survivorship: is it determined prior to ocean entry?

2015 ◽  
Vol 2 (1) ◽  
pp. 140312 ◽  
Author(s):  
Kentaro Morita ◽  
Nakashima Ayumi ◽  
Motohiro Kikuchi
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Total Mortality ◽  
Adult Survival ◽  
Oncorhynchus Keta ◽  
River Temperature ◽  
Seaward Migration ◽  
Key Factor ◽  
Short Term Mortality ◽  
Adult Survival Rate

Early life is believed to be a critical stage for determining survivorship in all fish. Many studies have suggested that environmental conditions in the ocean determine the fry-to-adult survival rate of Pacific salmon but few investigations have been conducted on the importance of the brief freshwater period during the seaward migration on overall survivorship. Here, we found that most of the variation in survivorship of hatchery-reared chum salmon ( Oncorhynchus keta ) was explained by river temperature during the fry stage, despite spending most of their life (approx. 99%) at sea. After the annual release of a constant number of fry, the number of fry moving through the river at a downstream location varied greatly. The number of returning adults was positively correlated with the number of fry moving downstream. This result suggests that most salmon mortality occurred prior to ocean entry, and that short-term mortality in the river is a key factor determining major fluctuations in total mortality. Although marine mortality is often invoked in the literature as a key factor determining total mortality of chum salmon, attention should also be paid to freshwater mortality to understand the population dynamics of this species.

Behavioral Ecology of Chum Salmon Fry (Oncorhynchus keta) in a Small Estuary

1974 ◽  
Vol 31 (1) ◽  
pp. 83-92 ◽  
Author(s):  
J. C. Mason
Keyword(s):  
Fresh Water ◽  
Behavioral Ecology ◽  
Chum Salmon ◽  
Oncorhynchus Keta ◽  
Natural Systems ◽  
Active Selection ◽  
Resource Managers ◽  
Salmon Fry ◽  
Seaward Migration ◽  
And Behavior

Chum salmon fry (Oncorhynchus keta) in the estuary of a small coastal stream exploited fresh water, estuarine, and marine food chains and, by so doing, were exposed to marked, daily fluctuations in salinity that demanded active selection of fresh water on ebbing tides day and night. The resulting delay in seaward migration and associated behavioral observations are inadequately reflected in published accounts of the life history and behavior of chum fry in natural systems and laboratory situations, and the downstream displacement theory. The biological basis for delayed seaward migration of chum fry merits the attention of fishery researchers and resource managers alike.

Rationalizing the Irrational: A Case Study in User Group Participation in Pacific Salmon Management

1987 ◽  
Vol 44 (10) ◽  
pp. 1796-1805 ◽  
Author(s):  
Ray Hilborn ◽  
Wilf Luedke
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Political Activity ◽  
Oncorhynchus Keta ◽  
Recent Attempt ◽  
Decision Making Process ◽  
User Group ◽  
Salmon Fisheries ◽  
Insight Into

Acrimony between industry and government managers is commonplace in the management of many Pacific salmon fisheries. A case study of the chum salmon (Oncorhynchus keta) fisheries in southern British Columbia provides insight into the prevailing distrust between fishermen and managers. A recent attempt to bring planned management into what had often been an irrational and highly political activity is described. A management system called the "clockwork" provides all fishermen an opportunity for greater understanding of the management rationale and greater input into the decision-making process. The results of this attempt and implications for achieving management goals are discussed.

scholarly journals Response of the Sea Louse Lepeophtheirus salmonis Infestation Levels on Juvenile Wild Pink, Oncorhynchus gorbuscha, and Chum, O. keta, Salmon to Arrival of Parasitized Wild Adult Pink Salmon

2006 ◽  
Vol 120 (2) ◽  
pp. 199
Author(s):  
Alexandra Morton ◽  
Rob Williams
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Primary Source ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Lepeophtheirus Salmonis ◽  
Louse Infestation ◽  
Age Cohorts

Recent recurring infestations of Sea Lice, Lepeophtheirus salmonis, on juvenile Pacific salmon (Oncorhynchus spp.) and subsequent annual declines of these stocks have made it imperative to identify the source of Sea Lice. While several studies now identify farm salmon populations as sources of Sea Louse larvae, it is unclear to what extent wild salmonid hosts also contribute Sea Lice. We measured Sea Louse numbers on adult Pink Salmon (Oncorhynchus gorbuscha) migrating inshore. We also measured Sea Louse numbers on wild juvenile Pink and Chum salmon (Oncorhynchus keta) migrating to sea before the adults returned, and as the two age cohorts mingled. Adult Pink Salmon carried an average of 9.89 (SE 0.90) gravid lice per fish, and thus were capable of infecting the adjacent juveniles. Salinity and temperature remained favourable to Sea Louse reproduction throughout the study. However, all accepted measures of Sea Louse infestation failed to show significant increase on the juvenile salmon, either in overall abundance of Sea Lice or of the initial infective-stage juvenile lice, while the adult wild salmon were present in the study area. This study suggests that even during periods of peak interaction, wild adult salmon are not the primary source of the recent and unprecedented infestations of Sea Lice on juvenile Pacific Pink and Chum salmon in the inshore waters of British Columbia.

Swimming speeds and buoyancy compensation of migrating adult chum salmon Oncorhynchus keta revealed by speed/depth/acceleration data logger

2001 ◽  
Vol 204 (22) ◽  
pp. 3895-3904 ◽  
Author(s):  
Hideji Tanaka ◽  
Yasuaki Takagi ◽  
Yasuhiko Naito
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Release Site ◽  
Oncorhynchus Keta ◽  
Horizontal Distance ◽  
Data Logger ◽  
Body Angle ◽  
Chum Salmon Oncorhynchus Keta ◽  
Acceleration Data ◽  
Free Ranging

SUMMARY Although the homing migration of Pacific salmon is well documented, the swimming behaviour of the returning salmon has been poorly described, principally as a result of the difficulties encountered in monitoring salmon behaviour in the sea. The present study describes the use of a recently developed electronic data logger to obtain simultaneous recordings of the swimming speed, depth, fin-beating activity and body angle of free-ranging chum salmon Oncorhynchus keta during their homing migration in coastal waters. Chum salmon migrated horizontally at speeds of 1.5–3.0 km h–1. The gross horizontal distance salmon moved during total recording periods were 1.24- to 19.0-fold greater than the net distance from the release site to the retrieval points. It is suggested that homing salmon did not drift passively but swam actively to the spawning grounds. Salmon preferred the surface water, but also made frequent vertical migrations. The travelled depth of each salmon ranged from 0.36 to 0.64 km per hour. Salmon descended at faster rates and steeper angles than they ascended. Both tailbeat frequency and tail thrust were higher during the ascent than the descent phase. These results suggest that chum salmon spent more energy during the ascent than the descent phase. Profiles of descent rate assumed an arched shape with respect to a change in hydrostatic pressure, while ascent rate increased with decreasing depth. High tailbeat frequencies were found during the course of ascent, which suggests that the salmon did not regulate the volume of air in the swim bladder during short-term vertical migrations.

SEX DIFFERENTIATION IN THE PACIFIC SALMON ONCORHYNCHUS KETA (WALBAUM)

1953 ◽  
Vol 31 (2) ◽  
pp. 73-79 ◽  
Author(s):  
J. G. Robertson
Keyword(s):  
Germ Cells ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Sex Differentiation ◽  
Primordial Germ Cells ◽  
The Other ◽  
Oncorhynchus Keta ◽  
Progressive Development ◽  
The Pacific ◽  
Female Phase

The differentiation of the gonad is described in chum salmon embryos and alevins. Contrary to classical findings in teleosts, sex differentiation in the chum salmon proceeds in the male or female direction without an intermediate female phase. From an initially indifferent gonad there is a progressive development of one sex or the other. The organ forms as a fold from the splanchnic mesoderm and, at the time of first appearance, contains primordial germ cells. These enlarge to form the definitive germ cells which, after a series of divisions, form smaller oogonia or spermatogonia. Oogonia are followed by primary and secondary (growing) oocytes, the appearance of which is the criterion of sex distinction. Spermatogonia continue to multiply but do not undergo growth in the alevin. The ovary develops an open endovarial canal and is supported by a prominent mesovarium. The testis remains small and, in the alevin, develops no ducts. It is suspended by a mesorchium.

Treatments Before Frozen Storage Affecting Thaw Drip Formation in Pacific Salmon

1977 ◽  
Vol 34 (9) ◽  
pp. 1431-1435 ◽  
Author(s):  
E. Bilinski ◽  
R. E. E. Jonas ◽  
Y. C. Lau ◽  
G. Gibbard
Keyword(s):  
Key Words ◽  
Chum Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Frozen Storage ◽  
Freezing Rate ◽  
Slow Freezing ◽  
Oncorhynchus Keta ◽  
Temperature Range ◽  
Chum Salmon Oncorhynchus Keta

Freshly caught chum salmon, Oncorhynchus keta, were stored in ice or refrigerated seawater for 0.3 and 10 days and were then gutted and frozen at two different rates (1 or 14.5 h through the temperature range of 0 to −5 °C). The amount of thaw drip (TD) was determined in steaks following 1.5, 4, 8, and 12 mo of storage at −28 °C. A significant increase in TD occurred with the slow freezing rate or with a delay before freezing. These effects were not suppressed by a prolonged frozen storage, which also produced an increase in TD. There was no marked difference between fish held in ice and refrigerated seawater before freezing. Similar results were obtained with coho salmon, O. kisutch, frozen without prior chill stowage. Key words: Pacific salmon, thaw drip, chill stowage, freezing rates Oncorhynchus keta, O. kisutch

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.

Decreased Seawater Adaptability of Chum Salmon (Oncorhynchus keta) Fry Following Prolonged Rearing in Freshwater

1982 ◽  
Vol 39 (3) ◽  
pp. 509-514 ◽  
Author(s):  
Munehico Iwata ◽  
Sanae Hasegawa ◽  
Tetsuya Hirano
Keyword(s):  
Body Weight ◽  
Chum Salmon ◽  
Sea Water ◽  
Oncorhynchus Keta ◽  
Direct Transfer ◽  
Chum Salmon Oncorhynchus Keta ◽  
Salmon Fry ◽  
Seaward Migration ◽  
Osmoregulatory Ability

Chum salmon (Oncorhynchus keta) fry weighing about 1 g maintained plasma Na+ concentrations at 134–140 mmol/L during seaward migration in the Otsuchi River. The plasma Na+ level increased slightly in the estuary, and reached 150–160 mmol/L in the fry caught in the bay. On direct transfer from freshwater to seawater, the plasma Na+ concentrations of the fry weighing 0.4–2.3 g increased markedly after 1 h and reached a maximum after 3–12 h. The fry of < 1.4 g attained sea water-acclimated plasma Na+ level of 156 mmol/L within 24 h after transfer, whereas fry of 1.8–2.3 g failed to adapt to seawater within 24 h. When seawater adaptability of fry of different lots was examined simultaneously in late April, 83–109 d after hatch, the smaller fry adjusted their plasma Na+ levels more easily than the larger fry: the smallest fry attained seawater level after 12 h without showing any peak. Changes in seawater adaptability of the same lots of fry were also followed until 5 mo after hatching, and the osmoregulatory ability of the fry in seawater decreased gradually with an increase in body weight or in the time spent in freshwater.Key words: chum salmon fry, seaward migration, plasma Na+ concentration, seawater adaptability, Oncorhynchus keta

scholarly journals Genome assembly, transcriptome and SNP database for chum salmon (Oncorhynchus keta)

2021 ◽  
Author(s):  
Eric B Rondeau ◽  
Kris A. Christensen ◽  
Dionne Sakhrani ◽  
Carlo A Biagi ◽  
Mike Wetklo ◽  
...  
Keyword(s):  
British Columbia ◽  
Linkage Group ◽  
Genome Assembly ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Gene Annotation ◽  
Oncorhynchus Keta ◽  
Specific Level ◽  
Genome Wide ◽  
The Pacific

Chum salmon (Oncorhynchus keta) is the species with the widest geographic range of the anadromous Pacific salmonids,. Chum salmon is the second largest of the Pacific salmon, behind Chinook salmon, and considered the most plentiful Pacific salmon by overall biomass. This species is of significant commercial and economic importance: on average the commercial chum salmon fishery has the second highest processed value of the Pacific salmon within British Columbia. The aim of this work was to establish genomic baseline resources for this species. Our first step to accomplish this goal was to generate a chum salmon reference genome assembly from a doubled-haploid chum salmon. Gene annotation of this genome was facilitated by an extensive RNA-seq database we were able to create from multiple tissues. Range-wide resequencing of chum salmon genomes allowed us to categorize genome-wide geographic variation, which in turn reinforced the idea that genetic differentiation was best described on a regional, rather than at a stock-specific, level. Within British Columbia, chum salmon regional groupings were described at the conservation unit (CU) level, and there may be substructure within particular CUs. Genome wide associations of phenotypic sex to SNP genetic markers identified two clear peaks, a very strong peak on Linkage Group 15, and another on Linkage Group 3. With these new resources, we were better able to characterize the sex-determining region and gain further insights into sex determination in chum salmon and the general biology of this species.

Detection and identification of Diphyllobothrium nihonkaiense plerocercoids from wild Pacific salmon (Oncorhynchus spp.) in Japan

2010 ◽  
Vol 84 (4) ◽  
pp. 434-440 ◽  
Author(s):  
J. Suzuki ◽  
R. Murata ◽  
K. Sadamasu ◽  
J. Araki
Keyword(s):  
Molecular Analysis ◽  
Detection Rate ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Oncorhynchus Masou ◽  
Detection Rates ◽  
Detection And Identification

AbstractWe investigated the risk of diphyllobothriasis from ingestion of wild Pacific salmon in Japan by surveying Diphyllobothrium plerocercoids in 182 salmon samples obtained from Japan. The plerocercoids were not detected in chum salmon (Oncorhynchus keta) (0/26), called Akizake in Japan, caught between September and November. However, the detection rate of plerocercoids in chum salmon, called Tokishirazu in Japan, caught between early April and June, was 51.1% (24/47) with an average of two plerocercoid larvae per fish. The detection rates of cherry salmon (Oncorhynchus masou) and pink salmon (Oncorhynchus gorbuscha) were 12.2% (10/82) and 18.5% (5/27), respectively, and the average number of plerocercoids per fish was 0.45 (37 larvae/82 fishes) and 0.22 larvae (6 larvae/27 fishes), respectively. Plerocercoids isolated from O. keta and O. masou were identified as Diphyllobothrium nihonkaiense on the basis of molecular analysis of the cox1 and nad3 genes. Moreover, four tapeworms (three from O. keta and one from O. masou) were obtained by infecting golden hamsters with plerocercoids. The morphological features of these tapeworms were similar to those of D. nihonkaiense isolated from humans. Therefore, we think that O. keta and not O. masou is the most important source of plerocercoid infections in Japan.

Sign in / Sign up

Export Citation Format

Share Document