Estimation of the Respiratory Rate of Young Plaice (Pleuronectes platessa L.) in Natural Conditions using Zinc-65

Abstract

THE dynamics of a population of 0 group plaice (that is, fish less than 1 year old) which live near the low water mark is being studied as part of an investigation of food chains on a sandy beach in Loch Ewe, Wester Ross. In this work, it is of prime importance that the respiratory rate of the fish in the sea be estimated, because the energy used for metabolism cannot be calculated unless this rate is known. Until recently it has been impossible to measure the respiratory rate of a fish in its natural environment. Mishima and Odum¹ have suggested, however, that the isotope zinc-65 may be used to measure this rate. These workers found that the elimination rate of zinc-65 from the body of the mollusc Littorina irrorata was related to the air temperature and to the body size of the animals, and they suggested that the isotope might be used to study the respiratory rate of the animal in its natural environment.