Survival of Eggs and Alevins of Atlantic Salmon ( Salmo salar) in Relation to the Chemistry of Interstitial Water in Redds in some Acidic Streams of Atlantic Canada

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Author: Lacroix, Gilles L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1985
• Subjects: Canada; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/f85-037; http://www.nrcresearchpress.com/doi/pdf/10.1139/f85-037

Eggs of Atlantic salmon (Salmo salar) were incubated in spawning areas of five streams of mean pH 4.6–6.5. Hatching success (36.6–88.7%) for eggs planted after fertilization in the natural substrate of four acidic streams was highly correlated with the pH (4.5–5.0) of interstitial water, and the LL50 was about pH 4.7. Dissolved oxygen concentrations (>6.0 mg∙L −1 ) in the interstitial water in these streams were probably not limiting to embryos before hatching. In a near-neutral stream (pH 6.5), the comparatively lower hatching success (5.6–77.0%) was significantly correlated with minimum dissolved oxygen concentration (1.4–9.2 mg∙L −1 ) in the interstitial water, and the mean survival of embryos was very low (16.2%) at oxygen concentrations <6.0 mg∙L −1 . Conditions in the substrate where eggs were incubated until hatching were representative of those in natural salmon redds. In one of the acidic streams (pH 4.8), dissolved oxygen concentrations in the interstitial water were low (2.0–7.6 mg∙L −1 ) after the hatch, and the emergence of salmon fry from natural redds was minimal, which indicated a low survival of alevins. Estimates of critical pH levels for salmon embryos differ between the laboratory and field approach and are probably site specific because survival in acid waters is determined by acidity, related chemical factors, and changes in water quality within the redd environment.