Effect of varying temperature regimes on the development of pink salmon (Oncorhynchus gorbuscha) eggs and alevins

1986 ◽  
Vol 64 (3) ◽  
pp. 670-676 ◽  
Author(s):  
Clyde B. Murray ◽  
Terry D. Beacham

Eggs and alevins from six odd-year, brood-line stocks of pink salmon (Oncorhynchus gorbuscha) spawning in southern British Columbia were incubated under varying temperature regimes and subjected to rapid temperature changes at specific developmental stages. Increasing or decreasing temperature regimes had no significant effect on egg and alevin survival. The inclusion of 2 or 4 °C in the temperature regime reduced egg survival. Rapid temperature changes from 12 to 1 °C late in development reduced alevin survival when compared with transfers from 8 to 1 °C. Hatching and emergence time varied inversely with mean incubation temperature. Decreasing temperature regimes produced longer and heavier alevins and fry than increasing temperature regimes. Low mean incubation temperatures from fertilization to fry emergence resulted in longer and heavier alevins and fry than those at higher mean temperature. Transfers from 8 or 12 °C to 1 °C early in development had a greater effect on alevin length and weight than transfers late in development. Temperature regimes can be manipulated to enhance survival, control development time, and increase alevin and fry size.

1988 ◽  
Vol 66 (12) ◽  
pp. 2634-2648 ◽  
Author(s):  
T. D. Beacham ◽  
C. B. Murray

Pink salmon stocks in British Columbia spawning from August through October were surveyed for variation in developmental biology from 1983 to 1985. Pink salmon in the even-year broodline tended to have higher embryonic survival and proportionately better embryonic and alevin growth at a low incubation temperature (4 °C) than did those in the odd-year broodline. Within a broodline, late-spawning stocks had slightly faster fry emergence timing than did early spawning stocks. Stocks within broodlines had different trends in alevin and fry size with respect to incubation temperature. Pink salmon in the even-year broodline appeared to be better adapted to a colder environment than those in the odd-year broodline. This may reflect a different recent origin of the two broodlines.


1987 ◽  
Vol 65 (1) ◽  
pp. 96-105 ◽  
Author(s):  
Terry D. Beacham ◽  
Clyde B. Murray

We transferred embryos of pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon from 8 to 2 °C at five stages of development: 16-cell stage, blastula stage, completion of epiboly, early eye pigmentation, and late eye pigmentation. Survival rates of the embryos increased the later in development that they were transferred to 2 °C. All pink salmon blastulas transferred died, whereas 50% of chum salmon blastulas transferred survived until hatching. After epiboly was complete, survival rates of the embryos subsequently transferred to 2 °C were usually in excess of 75%. Chum salmon embryos had higher survival rates than did pink salmon embryos at all transfer stages. Significant differences were found in embryo survival rates among stocks within species and among families within stocks. Fry from early-spawning chum salmon took longer for exogenous yolk absorption ("button-up") than did those from late-spawning ones. Alevins and fry from early transfers were generally smaller than those from later ones. Different trends in embryo and alevin survival rates and alevin and fry size among stocks within species and among families within stocks were assumed to be indicative of adaptive variation to variable natural incubation environments.


1994 ◽  
Vol 72 (5) ◽  
pp. 826-833 ◽  
Author(s):  
Terry D. Beacham ◽  
Clyde B. Murray ◽  
L. Walter Barner

Pink salmon (Oncorhynchus gorbuscha) embryos were obtained in April 1991 from the first generation of a 1989 brood line, which had been induced to spawn 6 months earlier than wild populations, which spawn in October. These embryos and subsequent juveniles were reared at a development temperature and under a photoperiod regime that induced some fish from this second generation to mature in October 1992, the correct time of year for spawning of wild populations. Other captive groups of pink salmon also matured in April 1993, permitting a comparison of fecundity, egg fertility, and egg size among female spawners in different photoperiods. Although the wild population spawns only in odd years, the captive population, originally derived from odd-year spawners, has been manipulated to spawn in even years. This shifting of the spawning time of the captive population may permit a transplant of odd-year genes into an even-year line, perhaps allowing the development of a run of even-year pink salmon in the Fraser River, British Columbia.


1965 ◽  
Vol 22 (6) ◽  
pp. 1477-1489 ◽  
Author(s):  
H. T. Bilton ◽  
W. E. Ricker

Among 159 central British Columbia pink salmon that had been marked by removal of two fins as fry and had been recovered in commercial fisheries after one winter in the sea, the scales of about one-third showed a supplementary or "false" check near the centre of the scale, in addition to the single clear-cut annulus. This evidence from fish of known age confirms the prevailing opinion that such extra checks do not represent annuli, hence that the fish bearing them are in their second year of life rather than their third. Unmarked pink salmon from the same area, and some from southern British Columbia, had a generally similar incidence of supplementary checks. In both marked and unmarked fish the supplementary checks varied in distinctness from faint to quite clear. In a sample of scales of 14 double-fin marked chum salmon which were known to be in their 4th year, all fish had the expected 3 annuli, and 12 fish had a supplementary check inside the first annulus.


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