Effect of Smolt Size on Smolt-to-Adult Survival for Chilko Lake Sockeye Salmon (Oncorhynchus nerka)

1991 ◽  
Vol 48 (6) ◽  
pp. 988-994 ◽  
Author(s):  
M. A. Henderson ◽  
A. J. Cass
Keyword(s):  
Sockeye Salmon ◽  
Interannual Variation ◽  
Oncorhynchus Nerka ◽  
Fork Length ◽  
Adult Survival ◽  
Threefold Increase ◽  
Limited Variation ◽  
Back Calculation ◽  
The Mean ◽  
Calculation Procedures

Three approaches were used to test the hypothesis that smolt-to-adult survival is independent of smolt size for Chilko Lake sockeye salmon (Oncorhynchus nerka). The mean distance between the focus of the scale and the first annulus, a reliable indicator of smolt size, was greater for adult scales than for smolt scales from the same brood year in two of the three years we examined. This indicated a higher smolt-to-adult survival for larger smolts in these brood years. The abundance of smolts of different fork lengths, based on back-calculation procedures from adult scales, was compared with the abundance of smolts of different fork lengths at the time of outmigration within brood years. In all three years studied, there was a two- to threefold increase in smolt-to-adult survival as smolt length increased. However, there was no significant relationship between smolt-to-adult survival and mean annual smolt fork length based on a 34-yr time series; this lack of relationship was probably caused by limited variation in mean annual smolt fork length over the 34-yr period and other variables, independent of smolt size, that affect survival and exhibit considerable interannual variation.

Size-Biased Survival in Steelhead Trout (Oncorhynchus mykiss): Back-Calculated Lengths from Adults' Scales Compared to Migrating Smolts at the Keogh River, British Columbia

1989 ◽  
Vol 46 (11) ◽  
pp. 1853-1858 ◽  
Author(s):  
B. R. Ward ◽  
P. A. Slaney ◽  
A. R. Facchin ◽  
R. W. Land
Keyword(s):  
Salt Water ◽  
Survival Rates ◽  
Length Distribution ◽  
Adult Survival ◽  
Steelhead Trout ◽  
Island Size ◽  
Back Calculation ◽  
Males And Females ◽  
The Mean ◽  
Calculation Procedures

Lengths of wild, winter-run steelhead smolts, estimated by back-calculation procedures from adults' scales, were compared with observed lengths of migrating smolts sampled near the mouth of the Keogh River, Vancouver Island. Size-biased smolt-to-adult survival rates were estimated for several length categories by utilizing length frequencies from observed smolts, smolt length frequencies which were back calculated from adults' scales, smolt yield, and adult returns. Back-calculated smolt length (BSL) of adults returning from smolts of 1977 to 1982 averaged 193 mm compared to 176 mm for observed smolt length (OSL). Mean BSL was larger than OSL in every year. Adults from odd-numbered smolt years had larger BSL than adults from even-numbered smolt years similar to the pattern in OSL. BSL increased with increased years spent in salt water, based on ageing adults' scales. Males and females had different BSL based on number of years spent in fresh water and salt water, although they exhibited the same mean BSL overall. The smolt-to-adult survival estimates were in close agreement with previous estimates derived from the mean OSL. Predictability of survival in the ocean based on the length of smolts was extended over a broad range of the length distribution of wild steelhead smolts.

Evidence for Size-Selective Mortality of Juvenile Sockeye Salmon (Oncorhynchus nerka) in Babine Lake, British Columbia

1987 ◽  
Vol 44 (4) ◽  
pp. 712-721 ◽  
Author(s):  
Cameron J. West ◽  
P. A. Larkin
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Length Distribution ◽  
Fork Length ◽  
Late Summer ◽  
Selective Mortality ◽  
Daily Growth ◽  
Back Calculation ◽  
Spawning Tributaries

Otolith – body length relations and back-calculation procedures were used to test the hypothesis that mortality of juvenile sockeye salmon (Oncorhynchus nerka) in Babine Lake, British Columbia, is size selective. Samples of the 1978 brood of sockeye were collected as fry from spawning tributaries as juveniles in the main basin, and as smolts at the outlet. Total otolith length was chosen as the most useful otolith dimension for back-calculation of fork length at emergence. Sockeye from the various tributaries show different fork length – otolith length relationships necessitating a weighting procedure for comparisons involving samples of mixed stocks from the lake. Instantaneous daily growth rate and In fork length during the early lake-rearing period were significantly correlated. Smaller juveniles grew more slowly than larger individuals in mid-july, and a hierarchy of sizes was maintained. The distributions of total otolith length at emergence for fry, surviving juveniles, and smolts indicate selective mortality of fish with smaller otoliths, hence of small size at emergence. Survivals from the lower and upper halves of the initial total otolith length distribution were 8.9 and 63.6%, respectively. Comparable estimates for back-calculated fork lengths at emergence were 27.2 and 43.4%. Size-selective mortality is most intense in the late summer and early autumn, and may be associated with predation and parasitism.

Fecundity and Egg Retention of Some Sockeye Salmon (Oncorhynchus nerka) Stocks in British Columbia

1986 ◽  
Vol 43 (8) ◽  
pp. 1643-1655 ◽  
Author(s):  
J. I. Manzer ◽  
I. Miki
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Absolute Fecundity ◽  
Egg Retention ◽  
Inadequate Sample Size ◽  
Egg Number ◽  
The Mean ◽  
The Relationship ◽  
Individual Fecundity

The fecundity and egg retention of anadromous female sockeye salmon (Oncorhynchus nerka) collected during 1971–82 from several stocks in British Columbia undergoing controlled fertilization to enhance adult sockeye production were examined. The relationship between egg number and postorbital–hypural length based on 863 females representing 14 stocks was not consistent between all age-types, stocks, and years, probably because of inadequate sample size in some instances. Combined samples, however, revealed a significant positive relationship between postorbital–hypural length and egg number for age 1.2, 1.3, and 2.2 females. Mean absolute fecundity for the respective age-types was 3218, 4125, and 3544 eggs. For samples of 10 or more females, significant stock and annual differences were detected when individual mean absolute fecundity was adjusted to a postorbital–hypural length of 447 mm, but not for females of different age. A comparison of mean fecundities for coastal stocks with historical data for interior British Columbia stocks suggests that coastal stocks are 18% more fecund than interior stocks. Possible causal mechanisms for this regional difference are hypothesized. Examination of 796 carcasses (representing five stocks) for egg retention revealed a range from totally spawned to totally unspawned females, with 56% of the carcasses containing 20 eggs or less and 68% containing 50 eggs or less. The mean egg retention based on all samples combined was estimated to be 6.5% of the mean individual fecundity. This value was reduced to 3.9% when stock means were averaged.

Pathogenesis of Infectious Hematopoietic Necrosis Virus in Adult Sockeye Salmon (Oncorhynchus nerka)

1982 ◽  
Vol 39 (8) ◽  
pp. 1144-1149 ◽  
Author(s):  
Dan Mulcahy ◽  
John Burke ◽  
Ron Pascho ◽  
C. K. Jenes
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Virus Concentration ◽  
Ovarian Fluid ◽  
Female Fish ◽  
Fish Virus ◽  
Infectious Hematopoietic Necrosis ◽  
The Mean ◽  
Mean Concentration ◽  
Pyloric Ceca

The concentration of infectious hematopoietic necrosis (IHN) virus was determined in eight organs and two body fluids from each of 60 adult sockeye salmon (Oncorhynchus nerka). Included in the sample were 4 males and 56 prespawning, spawning, or spent female fish. All fish were infected, and virus was present in nearly all organs. There was an overall tendency for the mean concentration to increase in many of the organs over time as the fish progressed in ripeness. In prespawning females, IHN virus could be detected in all organs and in ovarian fluid but not in serum; the incidences were highest in the gills, spleen, and pyloric ceca, and the titers were highest in the pyloric ceca and liver. Incidences of infection in the organs were higher in spawning than in prespawning females and higher still in spent females in which the incidence of virus was 100% in all organs except brains (78%) and sera (67%). Virus concentrations in organs or fluids ranged from 5 to 4.0 × 109 plaque-forming units per millilitre. In males, the highest incidences of virus were found in gills, pyloric ceca, and liver. The gills were the only organ in which the virus concentration in males exceeded that of females.Key words: infectious hematopoietic necrosis, IHN, fish virus, viral pathogenesis, sockeye salmon

Swimming Thrust of Sockeye Salmon (Oncorhynchus nerka) in Relation to Selectivity of Gillnets

1969 ◽  
Vol 26 (5) ◽  
pp. 1383-1385 ◽  
Author(s):  
R. H. Lander
Keyword(s):  
Significant Relationship ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fork Length

A significant relationship between girth at the mesh mark and fork length indicates that long sockeye salmon (Oncorhynchus nerka) have more swimming thrust than short ones. This tends to confirm a speculation of Regier and Robson (J. Fish. Res. Bd. Canada 23: 423–454, 1966). Preliminary conjecture relates the observation to the theory of mesh selectivity.

Migration Timing, Size, and Salinity Tolerance of Sea-Type Sockeye Salmon (Oncorhynchus nerka) in an Alaska Estuary

1989 ◽  
Vol 46 (4) ◽  
pp. 633-637 ◽  
Author(s):  
Jonathan Heifetz ◽  
Scott W. Johnson ◽  
K V. Koski ◽  
Michael L. Murphy
Keyword(s):  
Salinity Tolerance ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
River Estuary ◽  
Fork Length ◽  
Habitat Types ◽  
Southeast Alaska ◽  
Fish Size ◽  
Migration Timing

Migration timing, size, and salinity tolerance were determined for sea-type sockeye salmon (Oncorhynchus nerka), which migrate to sea as underyearlings (age-0), in the Situk River estuary, Southeast Alaska. Ten sites in three habitat types were seined monthly from Sate April through August, 1987, and age-0 sockeye from the estuary were tested for salinity tolerance. Age-0 sockeye were most abundant (up to 13∙m−2) from late April through June, and by late July, most sockeye had left the estuary. Mean fork length (FL) was 31 mm in April and increased 0.4 mm∙d−1 to 70 mm in late July when most (72%) remaining sockeye had grown to about the same size as age-1 smolts (69–95 mm) emigrating in May and June. Mean FL of age-0 sockeye in the estuary in July was 23 mm greater than in freshwater areas of the river. Salinity tolerance was directly related to fish size, and a size of at least 50 mm was required for 100% survival in seawater. Because salinity in the estuary ranged 0–30‰, sockeye of all sizes could survive in the estuary. Thus, in 3–4 mo, sea-type sockeye attained a size large enough to adapt to seawater and migrate to sea.

Sockeye salmon (Oncorhynchus nerka) nursery lake fertilization: Review and summary of results

2004 ◽  
Vol 12 (3) ◽  
pp. 133-162 ◽  
Author(s):  
K D Hyatt ◽  
D J McQueen ◽  
K S Shortreed ◽  
D P Rankin
Keyword(s):  
Food Web ◽  
Green Algae ◽  
Sockeye Salmon ◽  
Inorganic Nitrogen ◽  
Oncorhynchus Nerka ◽  
Adult Survival ◽  
Bottom Up ◽  
Blue Green Algae ◽  
Marine Survival ◽  
Lake Fertilization

We reviewed 24 sockeye salmon (Oncorhynchus nerka) nursery lake experiments that involved whole-lake fertilization with appropriate treatment and control years. We found that: 21 of 21 studies showed that fertilization was associated with increased chlorophyll a concentrations, 16 of 16 showed increased zooplankton biomasses, 16 of 16 demonstrated increased average smolt weights, and 11 of 13 showed increased smolt biomasses. Studies involving assessments of egg-to-smolt survival were rare, but all (4 of 4) showed increased survival rates. Studies involving increased smolt-to-adult survival (i.e., marine survival) were even rarer, but all (3 of 3) showed that lake fertilization and increased smolt size were associated with increased marine survival. Several fertilization studies reported problems, and some offered solutions. For instance, when whole-lake fertilization stimulated the growth of blue-green algae, fertilizer with higher nitrogen to phosphorus ratios was used to control the problem. Conversely, when high nitrogen to phosphorus ratios were associated with blooms of ungrazable diatoms, notably Rhizosolenia eriensis, reduced nitrate concentrations were recommended. To date, solutions designed to constrain the growth of both blue-green algae and Rhizosolenia blooms remain elusive. Some studies showed that when both mysids (large invertebrate planktivores) and juvenile sockeye inhabit the same lake, sockeye suffer from a competitive disadvantage and mysids consume 80–90% of the available zooplanktonic food production. Similarly, a small number of studies demonstrated that competition from sticklebacks (Gasterosteus aculeatus) adversely affected sockeye growth rates, and although the problem remains unresolved, ongoing work in lakes containing kokanee (O. nerka), suggests that stocked cutthroat trout (Salmo clarki) may be capable of controlling stickleback densities through predation. Despite all of these difficulties, in almost all cases, when lakes were fertilized with various mixtures of inorganic nitrogen and phosphorus, pelagic food web bottom-up control was strong enough and predictable enough to ensure that sockeye smolt biomass increased. We conclude that sockeye nursery lake fertilization is a technique that can contribute usefully to both the enhancement and conservation of sockeye salmon populations. Key words: sockeye salmon, lake fertilization, bottom-up, aquatic food web.

Relationship Between Thickness of Daily Growth Increments in Sagittae and Change in Body Weight of Sockeye Salmon (Oncorhynchus nerka) Fry

1982 ◽  
Vol 39 (10) ◽  
pp. 1335-1339 ◽  
Author(s):  
Kenneth H. Wilson ◽  
P. A. Larkin
Keyword(s):  
Body Weight ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Regression Line ◽  
Daily Growth ◽  
Daily Increments ◽  
Growth Increments ◽  
Fish Weight ◽  
Daily Change ◽  
Back Calculation

Sixty-four laboratory-reared sockeye salmon (Oncorhynchus nerka) fry were marked to enable identification as individuals. Each was weighed initially on June 6 or 8, 1979; and again on July 6; and surviving fish were weighed a third time on July 20. After the final weighing, sagittae were removed and a standard otolith radius, corresponding to each weight, was determined by counting back from the otolith edge the appropriate number of daily increments. The regression of ln otolith radius on ln fish weight was linear, with r2 = 0.92, demonstrating a relationship between mean thickness of a daily increment in sagittae, and mean daily change in weight of the fry. Using this regression line, previous weights were back calculated from corresponding otolith radii with errors in the order of 15%.Key words: otoliths, daily growth increments, back calculation, sockeye salmon

Smolt-to-AduIt Survival Patterns of Sockeye Salmon (Oncorhynchus nerka): Effects of Smolt Length and Geographic Latitude when Entering the Sea

1993 ◽  
Vol 50 (3) ◽  
pp. 600-611 ◽  
Author(s):  
Jeffery P. Koenings ◽  
Harold J. Geiger ◽  
James J. Hasbrouck
Keyword(s):  
Nonparametric Regression ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Adult Survival ◽  
Combined Effects ◽  
Geographic Latitude ◽  
Common Pattern ◽  
Lake Outlet ◽  
The Common ◽  
Survival Patterns

Variations in smolt-to-adult survival (SAS) of sockeye salmon (Oncorhynchus nerka) relative to smolt length and age and latitude of the nursery lake outlet were explored for six stocks in Canada, Russia, and Alaska (W. E. Ricker. 1962. J. Fish. Res. Board Can. 19: 531–560) and 12 Alaskan populations. SAS values ranged from <1 to 68% for age 1., 2., and 3. smolt populations of 54–200 mm in mean length. The common pattern underlying the SAS to smolt size relationship, determined by nonparametric regression (loess), was nonlinear with functionally distinct zones. SAS of smaller smolts increased (0.3–0.5 (%) SAS∙mm−1) with size, but SAS of smolts >90–100 mm (6–8 g) did not. Variation in SAS was explained by smolt size (30%) and a south to north dine of nursery lakes (21%) indexed by latitude. SAS of about 3 and 13% for threshold-sized age 1. smolts (60–65 mm) from southern and northern nursery lakes were consistent with sockeye biostandards for Canada (4.7%) and Alaska (12%), respectively. The combined effects of latitude and smolt length on SAS resulted in larger smolts at higher (>60°N) latitudes having seven times the SAS of smaller smolts at lower (<55°N) latitudes.

Host–Parasite Relationships Between Sockeye Salmon, Oncorhynchus nerka, and Salmincola californiensis (Copepoda: Lernaeopodidae)

1977 ◽  
Vol 34 (2) ◽  
pp. 191-202 ◽  
Author(s):  
Z. Kabata ◽  
B. Cousens
Keyword(s):  
Sockeye Salmon ◽  
Body Wall ◽  
Oncorhynchus Nerka ◽  
Mechanical Damage ◽  
Fork Length ◽  
Parasitic Copepod ◽  
Size Groups ◽  
Branchial Cavity ◽  
Host Parasite ◽  
First Time

The distribution of the parasitic copepod, Salmincola californiensis, on two size-groups (fry, fork length 3.2–5.8 cm; juveniles, fork length 10.2–27.0) of the sockeye salmon, Oncorhynchus nerka, is described. The existence of preferred sites for both groups is established. The distribution on the smaller fish differs from that on the larger in that on the former the copepods are most abundant in the region of pectoral and pelvic fins, whereas on the latter they are by far most common in the branchial cavity. Macroscopic and microscopic mechanical damage to the fish tissues, resulting from the presence and activity of the copepod, comprises injuries to gills, skin, muscle, and even bone. The "burrowing phenomenon" (failure on the part of the copepod to cease excavation of a completed cavity of implantation, resulting in perforation of body wall and penetration of the viscera) is reported upon for the first time.

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