Though it may not be necessary for fishermen to have a detailed knowledge of the behaviour of fish it is likely that the more they Know about the habits of the fish they are hunting the more successful they will be. To Increase the efficiency of fishermen is not, however, the sole reason for undertaking studies on behaviour. Such studies are carried out by Research Officers who are seeking information which will enable them to give sound advice concerning the proper management of the particular fishery with which they are concerned. In all cases the aim must be to utilize existing stocks of fish efficiently and economically without waste. Adequate numbers of fish must be left to breed and young fish must be allowed to grow to a commercially valuable size.