Genetic Differences in the Early Development and Growth of Sympatric Sockeye Salmon and Kokanee (Oncorhynchus nerka), and their Hybrids

1990 ◽  
Vol 47 (11) ◽  
pp. 2250-2260 ◽  
Author(s):  
Chris C. Wood ◽  
Chris J. Foote

Anadromous (sockeye salmon) and nonanadromous (kokanee) Oncorhynchus nerka spawn sympatrically yet appear genetically distinct in a number of rivers in British Columbia. To investigate whether genetic differences are maintained by selection against -hybrid" progeny, we raised pure and reciprocal crosses of Shuswap River sockeye and kokanee under controlled hatchery conditions. Sockeye eggs were larger and survived slightly better than kokanee eggs, regardless of male type, both to the eyed egg stage and as young fry. We observed no differences in survival among cross types during the remainder of the 460 d study. Rate of yolk absorption was similar in pure sockeye and pure kokanee alevins, but significantly faster in alevins sired by sockeye than those sired by kokanee. This indicates a male genetic effect which compensates for the difference in egg size. Hybrid alevins developed differently because egg size is mismatched with the male genotype. Growth rates of fry were significantly more variable within pure kokanee families than within pure sockeye families Hybrid crosses survived as well as pure crosses under the study conditions. However, any progeny resulting from hybrid crosses in nature may sustain higher mortality than those from pure crosses.

1973 ◽  
Vol 30 (12) ◽  
pp. 1799-1809 ◽  
Author(s):  
J. R. Brett

Fingerling and adult sockeye salmon (Oncorhynchus nerka) were subjected to long periods of sustained swimming (10–20 days) in air-saturated fresh water. Energy expended was computed from change in body composition and compared with the metabolic equivalent from multiple determinations of oxygen-consumption rate. Caloric loss from body substance exceeded that estimated from total oxygen uptake by an average of 19.8%. The reasons for the difference, and the assumptions involved, are discussed. The difference apparently arises from slight excretion of partially metabolized fuels (anaerobic metabolism) and loss from sloughed body tissues. An oxycalorific equivalent of 4.8 kcal/liter O2 is considered an acceptable value for fish.


2000 ◽  
Vol 78 (10) ◽  
pp. 1791-1805 ◽  
Author(s):  
M D McGurk

This study compared fecundity-length-latitude relationships between 25 kokanee populations (15 natural and 10 introduced) and 48 sockeye salmon populations. Significant differences confirmed the hypothesis that the two Oncorhynchus nerka variants follow different reproductive strategies: (i) fecundity is more highly correlated with length for kokanee than for sockeye salmon; (ii) kokanee have higher fecundity-length regression slopes and lower intercepts than sockeye salmon; (iii) kokanee populations share a common fecundity-length regression slope, but sockeye salmon populations do not; and (iv) average lengths and fecundities of kokanee decrease with increasing latitude, but those of sockeye salmon do not. The first three findings confirm that kokanee maintain a constant egg size while increasing egg number with increasing body size but that sockeye salmon increase both egg number and egg size with increasing body size. Kokanee egg sizes may be less variable than those of sockeye salmon because kokanee have lower and less variable energetic costs of spawning migration and tend to use spawning gravel with smaller and less variable particle sizes. Latitudinal clines in kokanee length and fecundity may reflect latitudinal gradients in temperature and duration of the growing season. Such environmental gradients may explain why kokanee populations are rarely found as far north as Alaska.


1987 ◽  
Vol 44 (11) ◽  
pp. 1963-1971 ◽  
Author(s):  
T. P. Quinn ◽  
C. C. Wood ◽  
L. Margolis ◽  
B. E. Riddell ◽  
K. D. Hyatt

Although it is widely accepted that adult Pacific salmon (Oncorhynchus spp.) spawn in their natal stream, there are few quantitative estimates of homing precision in wild populations. The prevalence of two myxosporean parasites, Myxobolus neurobius and Henneguya salminicola, indicated very precise homing in certain sockeye salmon (O. nerka) populations in British Columbia (Long and Owikeno lakes on the central coast and Sproat, Great Central, and Henderson lakes on Barkley Sound, Vancouver Island). These populations were also sampled for electrophoretic differences at 23 loci. Genetic differences were found among all five populations, and estimates of straying from these data corroborated the parasitological evidence that straying is rare (< 1%).


1985 ◽  
Vol 42 (11) ◽  
pp. 1696-1701 ◽  
Author(s):  
P. C. Craig

The Stikine River in southeastern Alaska supports two principal stocks of sockeye salmon (Oncorhynchus nerka). An expedient means of separating these stocks when they enter freshwater is by egg size and egg mass measurements. Eggs of sockeye that spawn in the Tahltan Lake system are smaller than sockeye spawning elsewhere in the Stikine drainage, a difference supported by an independent stock identification method (scale pattern analysis). Tahltan females have only slightly developed ovaries (1–3% of body weight) and small eggs (2.0–3.5 mm) when they enter freshwater; they enter the river earlier (2–3 wk) and travel farther upstream to spawn than non-Tahltan sockeye. The latter group has more developed ovaries (5–16% of body weight) and larger eggs (3.5–6.2 mm) when they enter the river. Thus, an assessment of egg sizes of sockeye caught in the river can provide on-site information about stock composition and run timing. These data and escapement counts at Tahltan Lake indicate that the total escapement to the Stikine in 1983 was 61 000 to 71 000 sockeye of which 45–53% were Tahltan stock and 47–55% spawned eleswhere in the drainage.


2003 ◽  
Vol 60 (7) ◽  
pp. 809-824 ◽  
Author(s):  
Randall M Peterman ◽  
Brian J Pyper ◽  
Brice W MacGregor

Fisheries scientists and managers are concerned about potential long-term, persistent changes in productivity of fish stocks that might result from future climatic changes or other alterations in aquatic systems. However, because of large natural variability and measurement error in fisheries data, such changes are usually difficult to detect until long after they occur. Previous research using numerous Monte Carlo simulation trials showed that a Kalman filter performed better than standard estimation techniques in detecting such trends in a timely manner. Therefore, we used historical data along with a Kalman filter that included a time-varying Ricker a parameter to reconstruct changes in productivity (recruits per spawner at a given spawner abundance) of eight Bristol Bay, Alaska, sockeye salmon (Oncorhynchus nerka) stocks over the past 40 years. Productivity generally increased for most stocks but varied widely for others and dramatically decreased in another. Such large changes in productivity are important for management. They greatly affected optimal spawner abundances and optimal exploitation rates, suggesting that in the future, scientists should consider using models with time-varying productivity parameters.


1969 ◽  
Vol 26 (5) ◽  
pp. 1263-1271 ◽  
Author(s):  
Douglas Weber ◽  
Roy J. Wahle

A finclip and a chemical (tetracycline) mark were applied, in similar numbers, to hatchery-reared fingerling sockeye salmon (Oncorhynchus nerka). In mark-sampling of returning adults 3 and 4 years after release from the hatchery, numerical comparison of fish with the two marks showed that fewer finclipped fish returned than expected. It was demonstrated that the tetracycline mark did not affect survival and that the difference between returns of fish with the two marks originated in mortality caused by finclipping. The mortality attributed to finclipping was estimated as 39%.


1992 ◽  
Vol 49 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Chris J. Foote ◽  
Chris C. Wood ◽  
W. Craig Clarke ◽  
John Blackburn

Anadromous sockeye salmon and nonanadromous kokanee (Oncorhynchus nerka) spawn sympatrically in locations across British Columbia, yet remain genetically distinct. To investigate the possibility that these differences are maintained by selection against hybrids of the two forms owing to differences in seawater adaptability, we raised pure and reciprocal crosses of Shuswap River sockeye and kokanee in controlled hatchery conditions and tested their seawater adaptabilities nine times over 2 yr. Sockeye, kokanee, and reciprocal hybrids all showed a seasonal cycle in their seawater adaptability, which was lowest in midwinter and highest in the spring. However, clear differences were evident among cross-types in the spring of their second year. Sockeye were the first to show increased seawater adaptabilities, hybrid groups next, and kokanee last. The observed differences could not be attributed to tank effects, or to differences in size, sex, or state of maturity.


1976 ◽  
Vol 33 (2) ◽  
pp. 307-313 ◽  
Author(s):  
J. R. Brett

The extent of metabolic and feeding requirements for fingerling sockeye salmon (Oncorhynchus nerka) are compared over the tolerable range of temperature. Scope for growth, derived from the difference between maximum and maintenance rations, is shown to relate to temperature in a manner similar to that for maximum growth rate. Metabolic scope is compared with scope for growth, supporting the general concept of scope for activity developed by Fry (1947).


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