6 
THE MARINE BIOLOGICAL ASSOCIATION. 
Jan., 1890. 
the grey cod used to be a winter fish only in the bays of the 
United States, going in the summer to Newfoundland for the 
cooler waters of the Arctic stream. Science, however, has 
been able to alter this habit. Under the direction of the 
Commission of Fisheries of the United States Government, 
the artificial incubation of cod-spawn is carried on with 
perfect success, although there are great difficulties in the 
way from natural enemies, etc. The cod thus artificially 
bred are attached to the place of their birth, and do not 
know their way to Newfoundland, and therefore keep to the 
shores of the States, and are now freely caught in the summer. 
Such a result, however, could not have been attained without 
much preliminary investigation into the conditions under 
which the cod-spawn develops, and the investigation could 
not have been made except by properly trained scientific 
experts, with properly equipped laboratories at their command. 
Again, the shad, which in America is largely used as food, 
was formerly subject at times to great diminution in 
numbers, greatly, of course, to the injury of both fisherman and 
consumer. Scientific investigation has now shown that the 
shad spawns on the sea-coast when the water is at a tempera¬ 
ture within a few degrees of 60°F.; if, however, cold rains 
lower the temperature to 55°, or hot weather raise it to 65°, the 
shad run out to sea to spawn, and four years afterwards 
there is a famine. This occurs no longer, as the Commission 
vessels now follow the shad to sea, secure the eggs, and hatch 
them artificially. These two instances will show how success¬ 
fully scientific research and methods can be applied to the 
solution of practical problems, It remains to mention a few 
of the many problems connected with fisheries which are 
still unsolved. 
One very pressing question is why fish have deserted the 
inshore districts and gone to sea. At present no reason can 
be assigned, but scientific research will no doubt soon give us 
an answer; and, on the other hand, we learn from such 
examples as those given above that much may be done by 
artificial hatching and rearing to recruit the inshore fisheries. 
Again, little or nothing is known about the development 
and conditions of life of many fish which are of great import¬ 
ance as food, for instance, the conger. There is obviously a 
wide field for research here, which promises the happiest 
results. 
Another subject of moment relates to the bait used for 
long-line fishing, an industry of considerable importance, 
conger, ray, skate, cod, and pollack being caught by this 
means. Squid is the principal bait, but pilchard, mackerel, 
