at a del 
PROGRESS IN BIOLOGICAL INQUIRIES, 1926 581 
be controlled, if that be possible. The greatest difficulty the bureau has to 
contend with is the scarcity of properly trained men interested in fishery 
investigations. * * *. 
Just what course scientific investigations of the fisheries should 
follow is a problem of greatest concern to all of us. I have asked 
Mr. Will F. Thompson, who has had many years of experience 1n 
fishery investigations of a rather technical type, to give us his ideas 
of what scientific investigations of the fisheries might well consist. 
SCIENTIFIC INVESTIGATION OF MARINE FISHERIES 
By Wi. F.. THomMPpson 
Director of scientific investigations, International Fishery Commission, United 
States and Canada 
It is generally accepted that the end and aim of governmental fisheries science 
is the conservation and the more adequate use of our fisheries. Under this, the 
detection and prevention of overfishing comes first, as far as the sea is con- 
cerned, for by far the greater number of our fishery industries are based upon 
species not capable of artiticial propagation or culture of any kind. Next in order 
ot importance comes the detection and foretelling of the great fluctuations in 
abundance due to natural causes, such as unusually abundant year classes. You 
will hear enough with respect to the latter before this conference is over. My 
purpose is to emphasize to you the great problems underlying the first great 
objective—the detection and prevention of overfishing. 
I wish to do this because I am firmly convinced that they are not only really 
great problems, from an economic standpoint, but also truly great problems to 
the biologist. The men engaged upon these major problems are not confined 
in their work to the economic application of principles already discovered; they 
are formulating those principles and attacking problems in which the investi- 
gator in pure biology should be proud to be interested. 
The fundamentals underlying the utilization of our sea fisheries have not yet 
attracted the attention they should. As one looks through the literature, it 
would appear as though the basic rule for the conduct of investigations has 
been the general one that everything connected with the fish or its environment. 
the ocean, is of importance and should be studied. This view is undoubtedly 
sound, but it is equivalent to saying that the study of everything on land is of 
importance when studying the production of beef cattle. The statement is too 
diffuse to have any meaning. It has led, in the case of the North Sea fisheries. 
to the comparative neglect of a really great problem—that of the nature of 
overfishing. 
To say that our problem, or group of problems, is the study of the decline in 
productivity of certain fisheries is trite. That definition is commonly accepted 
without any thought as to its real significance. Suppose that we attempt to 
probe a little deeper into the yield of a species of fish. We find very shortly 
that we do not know what overfishing really consists in, that we have no 
measure of the strain a species will stand, that we do not know the character 
or type of the reaction of the supply to the demand. Our ignorance is intolerable 
in view of the greatness of the stake, and the presence of constantly decreasing 
yields for the effort involved should stir us to some sort of action. Regardless 
of theory. the abundance of fish must not go on decreasing, especially in the 
face o* the fact that we are not at the crest of a period of exploitation but 
rather at the beginning of such an era 
This era of exploitation is accompanied by an era of constantly increasing 
effic ency. sufficient to mask for the time being whatever decline may really 
exist. One is tempted to date the beginning of intensive exploitation as far 
back as the application of steam to marine vessels and to railway transporta- 
tion: yet since that time new apparatus, new internal-combustion engines, new 
methods of handling have been devised, so that we find ourselves under the 
constant necessity of redefining what we mean by an intensive fishery. 
I am thinking specifically of such fisheries as those for the halibut, the plaice, 
and the albacore. The total yield may remain the same, yet when some accu- 
rate measure of fishing effort is used, it is seen that a far smaller catch is 
obtained for that effort and a far greater area is covered. One sees a con- 
