ON THE PROBLEM OF WATER TEMPERATURE INFLUENCE ON SEASONAL GROWTH OF JUVENILE COHO SALMON ONCORHYNCHUS KISUTCH IN THE LOWER REACHES OF THE BOLSHAYA RIVER IN 2007–2018

The water temperature difference between relatively cold and warm years is not significant for somatic growth and number of sclerites in the external zone of scale out of the annual ring («plus zone») for yearlings of coho salmon in the lower stream of the Bolshaya River (West Kamchatka). The temperature effect is ambiguous and depends on month. In 20 days since May 15, number of the sclerites formed in this zone is definitely higher in warm years (0.77 sclerites, on average) than in cold years (0.51 sclerites), but in 120 days the difference almost disappears: 10.39 sclerites in warm years and 10.13 sclerites in cold years. So, each scleritis forms in approximately 10.4 days during June-August, no matter either warm or cold year it is. In September, the number of sclerites in the «plus zone» could be even smaller in some warm years than in some cold years. The temperature effect absence can be explained by low temperature in the river during the whole period from May to October (6.44 о C in May, 8.80 о C in June, 11.83 о C in July, 12.25 о C in August, 10.10 о C in September, and 6.33 о C in October, on average), that is close to the lowest limit of the optimal temperature range for coho juveniles (11.5–16.8 о C). Difference of the yearlings body length is also insignificant: in the period of 20–90 days from May 15 of 2007–2018, their mean body length increased in 2–5 mm more in the years with temperature above the norm in July than in the years with temperature below the norm, but within the period from middle May to late August the increments values coincide frequently for both types of years. All differences in the body length and number of sclerites between the coho yearlings in warm and cold years do not exceed the level of statistical errors. That’s why merging of all materials on juvenile coho salmon in the Bolshaya River is recommended, without their separation to cohorts of warm and cold years.

juvenile coho salmon, age, scleritis, freshwater period, body length, cold year, warm year

1. Brett, J.R., Environmental factors and growth, in Fish Physiology, vol. 8: Bioenergetics and Growth, Hoar, W.S., Randall, D.J., Brett, J.R., Eds., New York: Academic Press, 1979, vol. 10, pp. 599–675.

2. Bugaev, V.F., Aziatskaya nerka (presnovodnyi period zhizni, struktura lokal’nykh stad, dinamika chislennosti) (Asian Sockeye Salmon (Freshwater Life History, Structure of Local Stocks, and Population Dynamics)), Moscow: Kolos, 1995.

3. Bugaev, V.F., Vronsky, B.B., Zavarina, L.O., Zorbidi, Zh.Kh., Ostroumov, A.G., and Tiller, I.V., Ryby reki Kamchatka (Fish of the Kamchatka River), Petropavlovsk-Kamchatsky: KamchatNIRO, 2007.

4. Bugaev, V.F., Rastyagaeva, N.A., and Travina, T.N., Issues of seasonal growth of juvenile sockeye salmon Oncorhynchus nerka in the Bolshaya River (western Kamchatka), in Dokl. 17–18 mezhdunar. nauchn. konf. “Sokhranenie bioraznoobraziya Kamchatki i prilegayushchikh morei” (Proc. 17–18th Int. Sci. Conf. “Conservation of Biodiversity in Kamchatka and the Adjacent Seas”), Petropavlovsk-Kamchatsky: Kamchatpress, 2018, pp. 42–56.

5. Bugaev, V.F. and Yarosh, N.V., Growth of scale for juvenile coho salmon in the Bolshaya River (West Kamchatka), Izv. Tikhookean. Nauchno–Issled. Inst. Rybn. Khoz. Okeanogr., 2014a, vol. 176, pp. 62–84. Bugaev, V.F. and Yarosh, N.V., Growth of scale for juvenile chinook salmon in the Bolshaya River (West Kamchatka), Izv. Tikhookean. Nauchno–Issled. Inst. Rybn. Khoz. Okeanogr., 2014b, vol. 177, pp. 139–151.

6. Vaganov, E.A., Skleritogrammy kak metod analiza sezonnogo rosta ryb (Scleritograms as a Method of Analysis of the Seasonal Growth of Fish), Novosibirsk: Nauka, 1978.

7. Zakharova, O.A. and Bugaev, V.F., On duration of freshwater period of West Kamchatka masu salmon Oncorhynchus masou, Izv. Tikhookean. Nauchno–Issled. Inst. Rybn. Khoz. Okeanogr., 2013, vol. 175, pp. 110–126.

8. Zorbidi, J.H., The dynamics of the abundance of Kamchatka coho salmon Oncorhynchus kisutch (Walbaum) and the ecology of its juveniles in fresh waters, Extended Abstract of Cand. Sci. (Biol.) Dissertation, Vladivostok, 1974.

9. Zorbidi, J.H., Kizhuch aziatskikh stad (Coho salmon of Asian herds), Petropavlovsk-Kamchatsky: KamchatNIRO, 2010.

10. Lakin, G.F., Biometriya (Biometrics), 4th ed., Moscow: Vysshaya Shkola, 1990.

11. Mina, M.V., On the method of determining the age of fish in population studies, in Tipovye metodiki issledovanii produktivnosti ryb v predelakh ikh arealov (Typical Methods for the Study of Productivity of Fishes within Their Ranges), Vilnius: Mokslas, 1976, part 2, pp. 31–37.

12. Mina, M.V. and Klevezal’, G.A., Rost zhivotnykh: analiz na urovne organizma (Animal Growth: An Analysis on the Level of Organism), Moscow: Nauka, 1976.

13. Nikol’skii, G.V., Ekologiya ryb (Fish Ecology), Moscow: Vysshaya Shkola, 1974.

14. Clutter, R.I. and Whitesel, L.E., Collection and interpretation of sockeye salmon scales, Int. Pac. Salmon Fish. Comm., 1956, vol. 9.

15. Weber Scannell, P.K., Influence of temperature on freshwater fishes: a literature review with emphasis on species in Alaska, Tech. Rep., Juneau, Alaska: Alaska Department of Fish and Game, Division of Habitat, 1992, no 91-1.