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Mechanisms involved in the injury and death of fish by chilling temperatures

University of British Columbia

The behaviour reactions and the mechanisms involved in the injury and death of goldfish (Carassius auratus) exposed to chill temperatures have been investigated. Upon direct transfer to colder water goldfish exhibit an initial shock reaction followed by a primary chill-coma reaction with the latter reaction sometimes being followed, after apparently normal recovery, by a secondary chill-coma that ends in death. The first two reactions are believed to result from the effect of an excessive thermal stimulation of the cells of the central nervous system whereas the death that follows the secondary chill-coma is attributed to a disruption of the osmotic regulatory system. Within the range of size compared (three to ten centimeters and one to twelve grams), the tolerance to chilling temperatures of goldfish of the same or nearly the same age increases as the size of the fish increases. Statistical analysis of this relation shows a significant positive correlation between the survival times and the weight of the fish over their length as well as a significant negative correlation between the survival times and the surface area of fish over their weight. Several factors are thought to be involved in this effect of size of fish on tolerance to chill temperatures, viz., the insulation and surface area of fish relative to body mass in relation to the rate of heat loss and therefore to the body temperature; the gill surface area of fish relative to body mass in relation to the rate of abnormal osmotic passage of water subsequent to a disruption of the osmotic regulatory system.

Text

2012-03-01

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http://hdl.handle.net/2429/41039

Zoology

University of British Columbia

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