Hematologic response of fish to changes in gas or hydrostatic pressure

Hematologic changes were studied in fingering salmon after rapid decompression from combined or independent exposure to gas and hydrostatic pressure. After decompression, fingerling salmon saturated with excess gas under pressure (10.1-40.6 m of seawater) suffered a decrease in thrombocyte counts and fibrinogen, prolonged prothrombin (PT) times, and increased fibrinolytic activity, plasma proteins, and erythrocyte counts in proportion to severity of the dive. After decompression, fingerling salmon exposed to increased pressure experienced an increase in thrombocyte counts and available fibrinogen, shortened PT times, increased erythrocyte counts, and decreased plasma protein levels. It appeared that pressure causes activation of the blood coagulation system of fish. This activation may predispose the fish to increased susceptibility to bubble-induced diffuse intravascular coagulation after rapid decompression. Furthermore, hemoconcentration after decompression may be a pressure-related phenomenon and not a response to bubble-induced anoxia.