
The loss of hyperosmoregulatory ability in migrating juvenile American shad, Alosa sapidissima
Canadian Journal of Fisheries and Aquatic Sciences
- By:
-
Joseph D. Zydlewski
and S.D. McCormick
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Abstract
Investigations on juvenile American shad (Alosa sapidissima) revealed several physiological changes associated with downstream migration. Plasma chloride decreased 20% in wild juvenile shad during the autumn migration. Migrants had lower condition factor and hematocrit than non-migrant shad captured by beach seining. Gill Na + ,K + -ATPase activity of migrant shad was higher than non-migrant; a 2.5-fold increase was observed in 1993, while a 57% increase was observed in 1994. Similar changes were observed in laboratory studies of shad maintained in fresh water under simulated natural temperature and photoperiod. Plasma chloride dropped 68% and gill Na + ,K + -ATPase activity increased 3-fold over a 3-month period. Decreased plasma chloride was associated with increased mortality. Increases in gill Na + ,K + -ATPase activity decreases in plasma chloride and osmolality, and incidence of mortality were delayed and moderated, but not eliminated, in shad maintained at constant temperature (24°C). Shad did not survive in fresh water past December regardless of temperature regime. In seawater, all shad survived and showed no perturbation of plasma chloride at 24°C or simulated natural temperature (above 4°C). The decline in hyperosmoregulatory ability, as influenced by declining temperatures, may serve as a proximate cue for autumnal migration.
Additional publication details
- Publication type:
- Article
- Publication Subtype:
- Journal Article
- Title:
- The loss of hyperosmoregulatory ability in migrating juvenile American shad, Alosa sapidissima
- Series title:
- Canadian Journal of Fisheries and Aquatic Sciences
- DOI:
- 10.1139/f97-144
- Volume:
- 54
- Issue:
- 10
- Year Published:
- 1997
- Language:
- English
- Publisher:
- NRC Research Press
- Contributing office(s):
- Leetown Science Center
- Description:
- 11 p.
- First page:
- 2377
- Last page:
- 2387