Relative estimation of ventilatory fow rate in the eel (Anguilla anguilla L.)

Freshwater eels (Anguilla anguilla L.) were experimented on in order to measure ventilatory flow rate (by means of a direct method of collecting expired water), and simultaneously, to record sub-opercular pressure changes and opercular displacements (operculogram). Significant correlations (p less than 0.01) were found between the ventilatory flow rate (V) and various characteristics of operculiogram records. The relationships which are significant in each fish experimented on are; V = a(f.lo) + b; V = a(f.Ao) % b and V = a(f.Ao2) + b(f: ventilatory frequency: Ao and lo: mean amplitude and result of integration of opercular tracings). Considering the technical difficulties in measuring the ventilation flow rate of the eel, the easier operculographic recording methods lead to a correct estimation of relative changes in ventilatory flow rate, by using the refined relationship: V = a(Ao1.63).