306 EIGHTH PACIFIC SCIENCE CONGRESS 



those which relate to the real abundance of the stock; and these in turn 

 are covered respectively by the first three and the last three of the 

 stages listed above. 



3. Oceanography and the Distribution of Fish 



In its broadest sense this is a question primarily of marine zoo- 

 geography, but for the fishery biologist the enquiry must press far 

 deeper, since, in point of fact, for each species of commercial impor- 

 tance he seeks to establish the ontogenetic distribution patterns and, 

 moreover, the seasonal, annual, and even secular modulations of these. 

 The great oceanographic cruises, of the Challenger and of others, have 

 since established the major features of our picture of marine zoogeo- 

 graphy and yet withal there remains much to be done to enable us to 

 evaluate unexploited areas and to be able to give fishermen the in- 

 formation on which they might plan the development of fishing 

 operations. 



'I'he zoogeographic account of the distribution of marine faunas is 

 in effect a generalized one referring to groujDs of species and to indi- 

 vidual species which characterise the fauna and serve as indicators of 

 identified conditions. The distribution patterns referred to in the zoo- 

 geographic account indicate the broadest limits within which the faunas 

 are observed to occur. 



The more restricted limits within which the various ontogenetic 

 stages move are not of as great importance to zoogeography as they said 

 their seasonal and other modulations are to fisheries. But the greater 

 pattern and its component parts are both the grosser manifestation of 

 the reaction of the individual organisms to the various elements of its 

 environment at the behest of its own physiology. The general adjust- 

 ment of the organism to its medium in respect of its respiratory and 

 osmo-regulatory requirements set the general limits within which it can 

 move differences, in these requirements, between ontogenetic stages 

 may, theoretically, give separate distributions to these stages. The nu- 

 tritional requirements and peculiar needs in respect of reproductive 

 habits, further complicate the picture as the organisms undertake feed- 

 ing and reproduction migrations in search of the situations where the 

 necessary conditions are satisfied. It is perhaps no misrepresentation to 

 say that in the first part of this enquiry, the task is to describe the dis- 

 tribution of the first and the conditions under which they are found, 

 whilst, in the second part, the task is to find means of predicting where 

 these conditions will be found— as a means to predicting where the fish 

 will be. It must be stressed, however, that the accurate account of dis- 

 tribution requires elucidation of the keenomics of the species. 



