ANALYSIS OF RAM VENTILATION OF FISH GILLS WITH APPLICATION TO SKIPJACK TUNA.

A study has been made of the means by which a steadily swimming fish Skipjack tuna obtains oxygen and eliminates carbon dioxide to the sea. The method employed makes use of all available measurements such as oxygen requirement, gill membrane area etc., together with analysis of the fluid flows and mass transfer to describe the system operations. The pressure losses in passing through the gill exchange system are shown to result in a resistance force which for steadily swimming fish utilizing ram ventilation must overcome by use of the swimming muscles. The ability of the fish to extract oxygen and eliminate carbon dioxide in a counterflow exchange system is calculated by use of a high speed computer which is programmed to include the effects of the blood dissociation characteristics. Arterial levels of the respiratory gases are found to be in essential equilibrium with sea water indicating ample respiratory surface area. No indication of need for active transport could be discovered. Author