A field-based assessment of oxygen supply to incubating Atlantic salmon(salmon salar) embryos

Oxygen fluxes through artificially created salmon redds within four UK rivers were quantified and assessed against survival to hatching of Atlantic salmon embryos. All sites recorded high spatial variability in survival. Minimum survival to hatching was zero at all sites. Maximum survival to hatching ranged from 35% to 91%. Mean survival to hatching ranged from 8·7% to 71%. Intra- and inter-site variations in rates of oxygen supply were observed. Generally, interstitial dissolved oxygen concentrations declined over the incubation period from a maximum recorded directly after redd creation, although localized fluctuations were recorded. Similarly, interstitial flow velocities declined over the incubation period from a maximum directly after redd creation to a minimum at hatching. With respect to the causes of embryo mortalities, oxygen supply was shown to be a stronger determinant of survival than interstitial oxygen concentration or interstitial flow velocity. To improve delineation of potential causes of embryo mortalities in the field, the statistical analysis was integrated within mass transfer theory of the processes controlling respiration to determine the likely mechanisms inhibiting respiration. Based on this analysis, mortalities were assessed to have resulted from periods of lethal oxygen concentrations, from periods of interstitial flow velocities that were insufficient to remove metabolic waste, or from combinations of oxygen concentration and interstitial flow that did not support respiratory requirements. A set of oxygen-supply-related thresholds for assessing incubation habitat quality are proposed.

embryonic salmonid survival, oxygen concentration, interstitial flow velocity, habitat quality

10.1002/hyp.6635

1099-1085

3087-3100

Greig, S.M.

9de52452-eae6-4223-9701-cf8693a43859

Sear, D.A.

ccd892ab-a93d-4073-a11c-b8bca42ecfd3

Carling, P.A.

8d252dd9-3c88-4803-81cc-c2ec4c6fa687