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Preparation of hatchery—reared chum fry for life at sea: osmoregulation dynamics
Author(s) -
ZAPOROZHEC O. M.,
ZAPOROZHEC G.V.
Publication year - 1993
Publication title -
fisheries oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 80
eISSN - 1365-2419
pISSN - 1054-6006
DOI - 10.1111/j.1365-2419.1993.tb00124.x
Subject(s) - smoltification , osmoregulation , hatchery , seawater , biology , salinity , fishery , fish <actinopterygii> , zoology , oceanography , ecology , salmonidae , geology , salmo
The development of saltwater tolerance was studied in chum fry reared in the Malkinsky hatchery (central Kamchatka, 200 km from the Sea of Okhotsk). Hypo‐osmoregulatory ability of fry was assessed by dynamics of plasma sodium concentration, 24 and 48 h after their transfer from fresh water to seawater (30%o), and by fry survival in seawater of 40%o salinity. Complete osmoregulation function in young chum was developed in seawater only in late June, despite their earlier development of silver body color and fairly high migration activity. No correlation was found between the weight of fish and their osmoregulatory abilities. The reasons for late smoltification of hatchery‐reared chum have not yet been clearly defined. One explanation might be the combined effect of low nocturnal temperatures and considerable daily fluctuations in temperature (more than 8 o C) during the period of egg incubation (in fall), as well as during smoltification of chum juveniles (spring‐early summer). Data on the osmoregulatory ability of chum smolts could be useful in forecasting their survival in the early marine period of life.