36 REPORT OF THE COMMISSIONER OF FISHERIES, 
selective breeding, and the prevention of mortality. Since the yearly 
hatch in the experimental pounds is now much larger than is required 
for the continuation of the work, the Bureau liberated in the marshes 
of Beaufort Harbor in September, 1914, 876 yearling terrapin. 
Study of frogs-—The correspondence of the Bureau reveals a very 
widespread interest in the subject of frog culture. Many ventures 
in the rearing of frogs for commercial profit have been made, but it 
does not appear that the results generally obtained have represented 
a distinct improvement over the natural conditions. Since the edible 
frogs are prolific breeders by nature and since the young will develop 
under a variety of conditions in pools and marshes, it appears evident 
that the problem of frog culture is not one of manipulation of the 
eggs, but rather one of providing such an abundance of food that 
a large proportion of the young may come to maturity and a desirable 
rate of growth be secured. During this fiscal year the Bureau has 
secured the services of a skilled investigator who will conduct a care- 
ful inquiry into the feeding habits, rate of growth, and conditions of 
existence of the commercial species of frogs. 
Investigation of the salmon—tThe study of the life history of the 
salmon of the Sacramento and Columbia rivers has been continued 
throughout the fiscal year. Just before the close of the year arrange- 
ments were made for further investigations of the breeding habits 
of the salmons in the hope of gaining knowledge of practical utility 
in the conservation and propagation of these fishes. 
Investigation of the tuna.—Within the past few years there has 
developed a very important industry in the canning of tuna on the 
Pacific coast. The product has already won a place of high esteem 
and a new fishery resource is thus discovered. Unfortunately for 
the highest development of the industry, the tuna can not be counted 
upon to appear in abundance with any regularity, and the conditions 
which induce the appearance or disappearance of the fishes are not 
understood. It ha sbeen the desire of the Bureau to investigate the 
habits of this fish in a thorough way and to follow their movements 
upon the open sea. Through the services of a temporary assistant 
a preliminary inquiry was conducted, and a number of fish were 
marked in the hope that some of them may be recovered at a later 
time and light thrown upon their migrations and rate of growth. 
An adequate investigation could be conducted only with the use of 
a seaworthy vessel, such as the Albatross. The limited funds avail- 
able for the operation of this vessel and the fact of other and prior 
demands for its services made it impracticable to make a suitable 
disposition for continuance of the inquiry. 
OCEANOGRAPHIC STUDIES. 
The important oceanographic work carried on by the Bureau 
partly upon its own resources and partly in cooperation with the 
Coast Guard Service, was detailed in the last annual report. During 
the present fiscal year an assistant from the Bureau has been regu- 
larly detailed for oceanographical observations upon the revenue 
cutter Seneca engaged in ice patrol and observation on the trans- 
Atlantic steamship lanes. From May 4 to the close of the fiscal 
year the schooner Grampus has been regularly employed in oceano- 
graphic observations off the coast of New England. The observa- 
