Measurement of gill area in fishes: practices and problems

Abstract

An account is given of a commonly accepted method for measurement of the gill area of fishes. A number of practical hints are included together with some warning about possible sources of error. In particular, these include sampling methods and reduction of errors due to shrinkage. Emphasis is given to the importance of weighting in the calculation of gill area. Problems which arise in comparisons of gills from different species are discussed and attention is drawn to possible errors that can be introduced by the reduction of all data to a given body weight offish. Such dangers are especially present where comparisons are made between fishes which may differ in weight by as much as four orders of magnitude.