Gill O2 consumption in a teleost fish, Gadus morhua

Stimulated by the many physiological functions of fish gills this study reports on perfusion studies of gill arches and head preparations from the Atlantic cod, Gadus morhua, with the objective of determining the oxygen requirement of gill tissues in situ. An additional objective was to assess what fraction of the gill tissue O2 consumption is taken up directly from ambient water without intervention of internal gill perfusion. At 15 degrees C and air-saturated ambient water about 58% of the total gill O2 requirement was taken up from the perfusate while 42% entered gill tissues directly from ambient water. In relation to total O2 uptake of intact cod fish the gill tissue requires 6.65% giving gill tissues a weight-specific O2 requirement of 95.2 microliter O2 . g body wt-1 . h-1 or nearly twice that of the intact fish (54.5 microliter O2 . g body wt-1 . h-1). It is discussed how the gill tissue O2 requirement influences the employment of the Fick principle for calculations of cardiac output in fishes.