GUSHING: LINK BETWEEN SCIENCE AND MANAGEMENT 



fisheries science in the Commissions there is one 

 general conclusion, that when the science is suc- 

 cessful the Commissions can work well but when 

 the scientific evidence is confused the Commis- 

 sions may fail. Of course, failure may occur for 

 other reasons; for example, a proposal in the ICES 

 to close the small plaice grounds in 1923 was re- 

 jected by the British fishing industry in 1926. 



THE NATURE OF 

 FISHERIES SCIENCE 



The organization of knowledge into science is 

 based on the establishment of laws that interlock. 

 Each law subsumes much information and the 

 network of laws comprises the body of the science. 

 Advance in science is made by the addition to or 

 the rearrangement of the network. Any scientific 

 conclusion is judged in relation to the general 

 framework, and it is tested in the premises and 

 extensions of the argument in the network. It is 

 sometimes said that the end of a scientific proce- 

 dure is to establish a correlation; without denying 

 the use of correlation, the most important point is 

 to establish whether the correlation is likely and 

 how it fits into the general scientific framework. 



In a highly developed science such judgments 

 are made frequently, but in a more primitive one 

 like fisheries biology the necessary network has 

 not yet been established. For example, all our in- 

 formation on stocks depends on catches, with the 

 various biases in availability included; indepen- 

 dent methods of estimating stock are being de- 

 veloped but they are not yet reliable. In a highly 

 developed science, a number of methods indepen- 

 dently yield the same result; fisheries biologists 

 are pleased to estimate fishing mortality but very 

 rarely is more than one method used. Natural 

 mortality is estimated as the difference between 

 total mortality and fishing mortality, and there is 

 very little independent evidence of its magnitude. 

 The information needed is accumulating quite 

 quickly but the science remains a little weak. 



Because biological material is highly variable, 

 any biologist needs a working knowledge of statis- 

 tics. Without denigrating this very real need, the 

 science needs more than statistics, more informa- 

 tion, more hjqjotheses, and more insight. It has 

 sometimes been stated that fish stocks could be 

 assessed by the study of ecosystems rather than by 

 the study of single populations. This is rubbish; it 

 is my view that not enough is known of any one 

 population primarily because we have examined 



adult animals to the exclusion of the juveniles. I do 

 not mean that we know nothing of fish larvae or 

 0-group fish, but that we know too little of their 

 growth rates and death rates. With more knowl- 

 edge of this sort, the problems of the regulation of 

 numbers and of competition might be solved and 

 we might at the same time learn something of how 

 an ecosystem itself is regulated. 



It has been said that fisheries science is fully 

 developed and that its techniques are quite reli- 

 able. Much is known about the Pacific salmon but 

 it is only a small fraction of what is needed. It has 

 been said that stock and recruitment is the last 

 problem in fish population dynamics. It is the 

 study of the regulation of numbers, of competition 

 between species, and of the variability of recruit- 

 ment. In other words, it is the central problem of 

 population dynamics. There is a sense in which 

 fisheries biologists have passed through a long 

 apprenticeship before they have embarked on the 

 real problem that concerns them. 



CONCLUSION 



The international management of fisheries has 

 developed slowly since it started during the second 

 and third decades of the present century. There 

 are many reasons for this, economic, social, and 

 political; indeed the agreement achieved between 

 nations is considerable when one considers all the 

 difficulties involved. One of the reasons for this 

 slow development, but not the only one, is that 

 where the science has failed, so has management. 

 Conversely, where the science has been success- 

 ful, management can proceed with confidence, 

 other things being equal. One would expect a link 

 to exist between science and management, as it 

 does in other fields. 



LITERATURE CITED 



Beverton, R. J. H., AND S. J. Holt. 



1957. On the dynamics of exploited fish populations. Fish. 

 Invest. Minist. Agric, Fish. Food ( G. B. ), Ser. 2,19, 533 p. 

 Clayden, a. D. 



1972. Simulation of the changes in abundance of the cod 

 (Gadus morhua L.) and the distribution of fishing in the 

 North Atlantic. Fish. Invest. Minist. Agric, Fish. Food (G. 

 B.), Ser. 2, 27(1), 58 p. 

 Gushing, D. H. 



1972. A history of some of the International Fisheries 

 Commissions. Proc. R. Soc. Edinb. Sect. B, Biol. 

 73:361-390. 



Gushing, D. H., and J. G. K. Harris. 



1973. Stock and recruitment and the problem of density 



863 



