OCEANOGRAPHY AND FISHERIES 305 



taxonomic study known as racial investigations, but it is in any case 

 a distribution study which must take reference to details in the bio- 

 nomics of the species. 



"Thirdly, the bionomics of the species must be discovered, that is 

 the general-life -history, ontogenology (embryology, growth, and geron- 

 tology), including feeding habits, reproduction and migratory habits. 



"Fourthly, the composition of the stocks is to be determined and, 

 if the stocks exist in separate units, this determination must be made 

 for each separately. This compositional study concerns the age, sex, 

 size, and maturity and other groups of the population. 



"This analysis generally reveals a fluctuation from year to year in 

 composition of the stocks. Frequently there is also considerable varia- 

 tion from area to area and between distinct segments of the stock. This 

 study should see, not only to describe the composition and its fluctua- 

 tion, but also to discover the causes of these fluctuations and, if possible, 

 to evolve a system of prediction of the appearance of the fluctuations. 



"Fifthly, following directly out of the fourth stage, there is to be 

 a measurement of the properties of the population. These properties 

 are potentials for growth and reproductions, and viability as a comple- 

 ment to the mortality which the stock sustains. In this stage there is 

 affected a considerable concentration of information since not only are 

 data on the bionomics and composition of the stocks to be reduced into 

 expressions summarizing the consequence of these structural features, 

 but there must also be a reference to physiological, physical and other 

 data concerning the factors which determine the properties of the pop- 

 ulation as a whole. This work should also aim at a prediction system. 



"Sixthly, the fishery biologist must then collaborate with the fishery 

 economist and fishery technologist in applying the general theory of 

 fishing to give mathematical expression to the relations between the 

 properties of the population and the effect of fishing operations." 



The essential feature of this programme is that it is concerned with 

 populations: its purpose is to develop a detailed description of the 

 population as a whole and of the response of the properties of the popu- 

 lation to changes in its environment, including among such changes, 

 of course, those in fishing intensity. 



The biologists' responsibility in respect of these populations is one 

 or the other of two kinds, which may be summed up in tw^o questions: 

 Firstly, what type of population and where? Secondly, of what abun- 

 dance? The first question belongs in the main to the exploratory stage, 

 the second to the management stage. In a way, also, these questions 

 correspond to the different enquiries concerning abundance; those 

 which relate to the availability of the fish to fishing operations, and 



