Gillnet Selectivity on Sockeye (Oncorhynchus nerka) and Pink Salmon (O. gorbuscha) of the Skeena River System, British Columbia

1971 ◽  
Vol 28 (6) ◽  
pp. 821-842 ◽  
Author(s):  
Ian St. P. Todd ◽  
P. A. Larkin
Keyword(s):  
Sockeye Salmon ◽  
Pink Salmon ◽  
Mesh Size ◽  
Retention Rates ◽  
Age Class ◽  
Short Period ◽  
Length Range ◽  
Mesh Ratio ◽  
Mean Size ◽  
Skeena River

Exploitation of Skeena River sockeye salmon has been conducted almost solely by drift gillnets since 1875. This study was designed to determine the selective properties of nylon gillnets presently in use; to compare these with properties of linen nets used prior to 1955; and, using statistics of catch and escapement, to estimate the selective action of the fishery as a whole on sockeye and pink salmon in 1968.Unique selectivity curves for nylon nets of [Formula: see text] mesh size could not be determined from sockeye catches. Mean size of age class 1.2 sockeye increased with mesh size but mean size of the predominant age class 1.3 sockeye demonstrated no trend. Age class 1.3 sockeye were among the largest on record and were too large to gill properly in all mesh sizes used.Comparison of [Formula: see text] mesh nylon gillnet with linen nets of [Formula: see text] mesh used in the historic fishery was also influenced by the large size of age class 1.3 sockeye. Nylon nets were 2.5 and 2.7 times as efficient as linen for sockeye, and 8.0 and 9.0 times for pink salmon. Nylon gillnets caught larger sockeye and pink salmon than did linen. Variances of mean size were also greater for catches in nylon.The statistics of catch and escapement for 1968 indicated that selection increased over the length range of age 1.2 sockeye but decreased over the length range of age class 1.3 sockeye. For pink salmon, which were extremely small in 1968, selection was increasingly large for larger size males and females. The length–girth relations of the species and sexes accounted for most of the difference between the selectivity curves. Retention by gillnets declined once the girth/mesh ratio exceeded 1.2 for sockeye. For pink salmon, no females were of a size to equal this ratio; the descending limb of the selectivity curve was due solely to males as the retention rates declined once girth/mesh ratio exceeded 1.0.These findings suggest that in most years the gillnet fishery on the Skeena River would tend to select relatively larger sockeye salmon. In years such as 1968, however, selection would be against smaller fish. This frequent reversal combined with the intense modern fishery, which tends to remove virtually all fish during a short period and allows almost complete escapement in periods between fishing, suggests that selective fishing has probably not been a significant factor in decreased production.

The Skeena River Salmon Fishery, with Special Reference to Sockeye Salmon

1955 ◽  
Vol 12 (3) ◽  
pp. 451-485 ◽  
Author(s):  
D. J. Milne
Keyword(s):  
Special Reference ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pink Salmon ◽  
Relative Size ◽  
Accurate Data ◽  
Gill Net ◽  
History Of ◽  
Skeena River ◽  
Salmon Fishery

The general history of the Skeena River commercial salmon fishery is presented from 1877 to 1948. The changes in fishing areas, seasons and fishing methods are described, together with the trends in the catches obtained. The most accurate data pertain to the important sockeye salmon gill-net fishery. The sockeye catch attained a maximum of 187,000 cases in 1910 and since then has declined to a minimum of 28,000 cases in 1933 and 1943. In recent years the catches have tended to level off. The pink salmon catches declined markedly after 1930. The chum catches also appear to have declined in recent years. Whether or not the spring and coho salmon catches have declined is not known. The size of the sockeye catch appears to be the best available measure of the relative size of the population. An analysis of the age cycles in the catch of sockeye and pink salmon did not reveal a practical basis for prediction. Some possible changes in the fishing regulations are discussed and the need for more data on the fluctuations in the size of the stocks during the fresh water phase is stressed.

A Comparison of Sockeye Salmon Catches at Rivers Inlet and Skeena River, B.C., with Particular Reference to Age at Maturity

1958 ◽  
Vol 15 (3) ◽  
pp. 331-354 ◽  
Author(s):  
Harold Godfrey
Keyword(s):  
Sockeye Salmon ◽  
Environmental Influence ◽  
Size Variation ◽  
Age At Maturity ◽  
River Systems ◽  
Age Composition ◽  
Age Class ◽  
Skeena River ◽  
Two Populations

Age composition, size and sex data for sockeye salmon catches (1912–1954) at Rivers Inlet and Skeena River, B.C. were compared. For both river systems there were indications of 4- and 5-year cycles of abundance among the 4- and 5-year-old fish, respectively; but the two populations were not necessarily in phase. Tests for correlation between the numbers of parental and offspring fish strongly suggested the dominance of hereditary over environmental influence in determining age at maturity. The two stocks showed much similarity in annual size variation, among each sex and age-class.

scholarly journals TRAUMATIZATION BY LAMPREYS OF SOCKEYE SALMON ONCORHYNCHUS NERKA (WALBAUM, 1792) IN THE MEYNYPIL’GYN LAKE-RIVER SYSTEM (KORYAK COAST OF CHUKOTKA)

2019 ◽  
Vol 198 ◽  
pp. 3-18
Author(s):  
E. V. Golub’ ◽  
A. P. Golub’
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Russian Far East ◽  
Pink Salmon ◽  
Far East ◽  
River System ◽  
Oncorhynchus Gorbuscha ◽  
Small Fish ◽  
Mean Size ◽  
Arctic Lamprey

Data on traumatization of sockeye salmon Oncorhynchus nerka spawners in the Meynypil’gyn lake-river system by lampreys are presented on results of observations in 1998– 2018. Features and localization of injuries are described comparing the injuries of males and females and biological parameters of fish with and without the injuries. In the Meynypil’gyn lake-river system, relative to other areas of Russian Far East, the portion of fish with injuries from lampreys is medium for sockeye salmon, and low for pink salmon Oncorhynchus gorbuscha and charr Salvеlinus malma. Judging by size of the wounds, the injuries were caused mostly by arctic lamprey Entosphenus tridentatus. Generally, about 68 % of sockeye spawners were attacked by lampreys during their pre-spawning migrations just before entering the fresh waters, but the percentage (P) depends on length (L) of fish: P = 1.2026 . L + 1.2192 (R2 = 0.879). So, the portion of injured fish increased from 2.7 % for the sockeye producers with length < 500 mm to 31.2 % for those with length 671–680 mm. Mean size and weight of the male and female sockeye spawners with traces of lampreys were statistically significantly higher than these parameters for the fish without injuries. The males injured by lampreys were larger than the males without injures in 18 mm and 295 g, the females — in 5 mm and 80 g, on average. Sockeye females had weaker and less numerous damages, so their portion among the fish with 1 injury was 45.4 %, among the fish with 2 injuries — 42.9 %, among the fish with 3 or more injures — 37.0 %. Besides, mean size of the injured sockeye increased with a number of injures and for the groups with 1, 2, and 3 or more injures it was for females: 604, 608, and 613 mm, for males: 655, 667, and 674 mm, respectively. Such dependencies of alive fish traumatization on their size are caused by higher mortality of small fish after lampreys attacks. There is concluded that arctic lamprey affects significantly on sexual and size composition of sockeye spawners in the Meynypil’gyn lake-river system providing selection of fish with larger size and weight, in particular males.

On the Distribution of Young Sockeye Salmon (Oncorhynchus nerka) in Babine and Nilkitkwa Lakes, B.C.

1956 ◽  
Vol 13 (5) ◽  
pp. 695-708 ◽  
Author(s):  
W. E. Johnson
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fishing Effort ◽  
Lake Area ◽  
Parent Population ◽  
Unequal Distribution ◽  
The North ◽  
Limited Dispersal ◽  
Mean Size ◽  
Skeena River

Babine Lake and connected Nilkitkwa Lake, a total lake area of 174 square miles, provide nursery facilities for progeny of the largest sockeye salmon run to the Skeena River in northern British Columbia.Based on catch per unit of fishing effort, tow-net collections in August and October, 1955, indicate that at least 67%, and possibly as much as 88%, of the total age 0 sockeye population of these lakes (estimated as 50 to 60 million) was concentrated in Nilkitkwa Lake and the North Arm of Babine Lake: that is, in 11.4% of the total lake area. Mean size of young sockeye in these areas of concentration was much smaller than in the sparsely populated remainder of Babine Lake.This unequal distribution of young sockeye, and resulting inefficient utilization of the lake nursery facilities, is apparently a result of the distribution of the spawning parent population and a limited dispersal of young sockeye from their points of entrance into the lake as fry.

scholarly journals Pacific salmon abundance trends and climate change

2011 ◽  
Vol 68 (6) ◽  
pp. 1122-1130 ◽  
Author(s):  
James R. Irvine ◽  
Masa-aki Fukuwaka
Keyword(s):  
Climate Change ◽  
Pacific Ocean ◽  
North Pacific ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
North Pacific Ocean ◽  
Pink Salmon ◽  
The North ◽  
Abundance Trends

Abstract Irvine, J. R., and Fukuwaka, M. 2011. Pacific salmon abundance trends and climate change. – ICES Journal of Marine Science, 68: 1122–1130. Understanding reasons for historical patterns in salmon abundance could help anticipate future climate-related changes. Recent salmon abundance in the northern North Pacific Ocean, as indexed by commercial catches, has been among the highest on record, with no indication of decline; the 2009 catch was the highest to date. Although the North Pacific Ocean continues to produce large quantities of Pacific salmon, temporal abundance patterns vary among species and areas. Currently, pink and chum salmon are very abundant overall and Chinook and coho salmon are less abundant than they were previously, whereas sockeye salmon abundance varies among areas. Analyses confirm climate-related shifts in abundance, associated with reported ecosystem regime shifts in approximately 1947, 1977, and 1989. We found little evidence to support a major shift after 1989. From 1990, generally favourable climate-related marine conditions in the western North Pacific Ocean, as well as expanding hatchery operations and improving hatchery technologies, are increasing abundances of chum and pink salmon. In the eastern North Pacific Ocean, climate-related changes are apparently playing a role in increasing chum and pink salmon abundances and declining numbers of coho and Chinook salmon.

Protandry in Pacific salmon

2000 ◽  
Vol 57 (6) ◽  
pp. 1252-1257 ◽  
Author(s):  
Yolanda Morbey
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Statistical Procedure ◽  
Timing Data ◽  
Mating Opportunities ◽  
Gender Specific ◽  
Specific Timing

Protandry, the earlier arrival of males to the spawning grounds than females, has been reported in several studies of Pacific salmon (Oncorhynchus spp.). However, the reasons for protandry in salmon are poorly understood and little is known about how protandry varies among and within populations. In this study, protandry was quantified in a total of 105 years using gender-specific timing data from seven populations (one for pink salmon (O. gorbuscha), three for coho salmon (O. kisutch), two for sockeye salmon (O. nerka), and one for chinook salmon (O. tshawytscha)). Using a novel statistical procedure, protandry was found to be significant in 90% of the years and in all populations. Protandry may be part of the males' strategy to maximize mating opportunities and may facilitate mate choice by females.

Changes in the Average Size and Average Age of Pacific Salmon

1981 ◽  
Vol 38 (12) ◽  
pp. 1636-1656 ◽  
Author(s):  
W. E. Ricker
Keyword(s):  
Growth Rate ◽  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Gill Nets ◽  
Growing Seasons ◽  
Mean Size ◽  
Average Size

Of the five species of Pacific salmon in British Columbia, chinook salmon (Oncorhynchus tshawytscha) and coho salmon (O. kisutch) are harvested during their growing seasons, while pink salmon (O. gorbuscha), chum salmon (O. keta), and sockeye salmon (O. nerka) are taken only after practically all of their growth is completed. The size of the fish caught, of all species, has decreased, but to different degrees and over different time periods, and for the most part this results from a size decrease in the population. These decreases do not exhibit significant correlations with available ocean temperature or salinity series, except that for sockeye lower temperature is associated with larger size. Chinook salmon have decreased greatly in both size and age since the 1920s, most importantly because nonmaturing individuals are taken by the troll fishery; hence individuals that mature at older ages are harvested more intensively, which decreases the percentage of older ones available both directly and cumulatively because the spawners include an excess of younger fish. Other species have decreased in size principally since 1950, when the change to payment by the pound rather than by the piece made it profitable for the gill-netters to harvest more of the larger fish. Cohos and pinks exhibit the greatest decreases, these being almost entirely a cumulative genetic effect caused by commercial trolls and gill nets removing fish of larger than average size. However, cohos reared in the Strait of Georgia have not decreased in size, possibly because sport trolling has different selection characteristics or because of the increase in the hatchery-reared component of the catch. The mean size of chum and sockeye salmon caught has changed much less than that of the other species. Chums have the additional peculiarity that gill nets tend to take smaller individuals than seines do and that their mean age has increased, at least between 1957 and 1972. That overall mean size has nevertheless decreased somewhat may be related to the fact that younger-maturing individuals grow much faster than older-maturing ones; hence excess removal of the smaller younger fish tends to depress growth rate. Among sockeye the decrease in size has apparently been retarded by an increase in growth rate related to the gradual cooling of the ocean since 1940. However, selection has had two important effects: an increase in the percentage of age-3 "jacks" in some stocks, these being little harvested, and an increase in the difference in size between sockeye having three and four ocean growing seasons, respectively.Key words: Pacific salmon, age changes, size changes, fishery, environment, selection, heritability

Toxicity of Various Formulations of 2,4-D to Salmonids in Southeast Alaska

1974 ◽  
Vol 31 (4) ◽  
pp. 480-485 ◽  
Author(s):  
William R. Meehan ◽  
Logan A. Norris ◽  
Howard S. Sears
Keyword(s):  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pink Salmon ◽  
Butyl Ester ◽  
Southeast Alaska ◽  
Dolly Varden Char ◽  
Salmon Fry ◽  
Percent Mortality ◽  
The Mean ◽  
Made In

To determine acute toxicity to juvenile (1) pink, chum, coho, and sockeye salmon, (2) Dolly Varden char, and (3) rainbow trout, 2,4-D acid, butyl and isooctyl esters were tested in southeast Alaska. A comparable test was made in Oregon using coho salmon fingerlings. The mean percent mortality after 96 h and the highest concentration of herbicide that did not produce any mortality were determined for each formulation tested.At less than 50 ppm 2,4-D acid produced no mortality except in pink salmon fry. The butyl ester was most toxic causing nearly complete mortality in all species at concentrations > 1.0 ppm and the isooctyl ester least toxic of the ester formulations. Alaskan and Oregon coho fingerlings were similar in their responses to 2,4-D acid, butyl and isooctyl esters. The toxicities of three different formulations of isooctyl ester, a PGBE ester, and butyl ester to Alaskan coho fingerlings were also determined. There were few or no differences in toxicity among isooctyl ester formulations. The butyl and PGBE esters were similar in toxicity.

Nonlinear Relation Between Smolts and Adults in Babine Lake Sockeye Salmon (Oncorhynchus nerka) and Implications for Other Salmon Populations

1982 ◽  
Vol 39 (6) ◽  
pp. 904-913 ◽  
Author(s):  
Randall M. Peterman
Keyword(s):  
Measurement Error ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Life Stage ◽  
Pink Salmon ◽  
Accurate Estimate ◽  
Large Variability ◽  
Marine Life ◽  
Mortality Effect ◽  
Marine Survival

Data on sampling variability in smolt abundance for Babine Lake sockeye salmon (Oncorhynchus nerka) are combined with a previous analysis to calculate a more accurate estimate of the degree of nonlinearity in the relation between smolts and adults. Results indicate significant within-stock nonlinear mortality, large variability in mortality which tends to obscure any smolt-to-adult relation, or both. Analysis of age structure data identifies the first 15 mo of marine life as the period when most of this nonlinear or relation-masking mortality occurs. I also calculate the amount of smolt measurement error below which other salmon stocks are classed as having nonlinear marine survival. A distinct separation between even and odd brood year marine survival of Babine Lake sockeye suggests interactions with pink salmon. Juvenile pink salmon (O. gorbuscha) abundances correlate positively with residuals in Babine Lake sockeye survival for the same seaward migration year. This suggests a depensatory mortality effect which occurs later in the marine life stage than the possible within-population compensatory effect. Depensation is plausible because the size of pink fry equals that of sockeye smolts by August in coastal waters, permitting mutual swamping of predators. The paper concludes with implications for further enhancement.Key words: density dependence, marine survival, measurement error, enhancement, depensation, nonlinear, variability

Comment: Population Structure and Run Timing of Sockeye Salmon in the Skeena River, British Columbia

2014 ◽  
Vol 34 (6) ◽  
pp. 1167-1170 ◽  
Author(s):  
Michael H. H. Price ◽  
Andrew G. J. Rosenberger ◽  
Greg G. Taylor ◽  
Jack A. Stanford
Keyword(s):  
British Columbia ◽  
Population Structure ◽  
Sockeye Salmon ◽  
Skeena River ◽  
Run Timing
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