98 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
encouraging results have attended the observations made in San Fran- 
cisco Bay with respect to the breeding of the Atlantic coast oyster, and 
an important scientific investigation has been conducted off the west- 
ern coast of Mexico and Central America, under the direction of Prof. 
» Alexander Agassiz. 
The field operations on the Atlantic coast have been directed chiefly 
tothe study of the oyster-grounds of Long Island Sound, of Tangier 
Sound in Maryland and Virginia, and of the coast of South Carolina. 
Extensive surveys were made in Long Island Sound with respect, 
mainly, to the conditions of the bottom, the natural enemies of the oys- 
ter, and the varying distribution of the set of spat. Theabsence of any 
pollution in the oyster-ground waters was also fully demonstrated by 
careful physical and chemical observations. The extent and causes of 
the deterioration of tlie oyster beds in Chesapeake Bay has been made 
the subject of a specialinvestigation, which is still in progress, Tangier 
and Pocomoke sounds having been selected for the first examinations. 
The inquiries in South Carolina were conducted for the purpose of as- 
certaining the character and distribution of the natural oyster-cultural 
resources and of determining the proper measures for their develop- 
ment. The work was completed in the course of a single winter, and 
has afforded very satisfactory results. Arrangements have also been 
made for the preparation of a series of reports descriptive of the meth- 
ods of oyster-culture practiced in European countries, which will, it is 
hoped, be at least suggestive to American oyster-growers. 
The study of the physical characteristics of the coast waters off the 
Northern Atlantic States, especially in the region traversed by the 
mackerel during their seasonal migrations, has been taken up for the 
first time in a thoroughly comprehensive manner, and has now been 
actively prosecuted during two summers. While the principal part of 
this work has been limited to the southern New England coast, a series 
of observations has also been carried southward to Virginia. These 
inquiries will have an equal bearing upon the habits of all other migra- 
tory fishes which resort to this region during a greater or less part 
of each year, and nearly all of the important economic species which 
enter into the fisheries there are of this character. 
Among the investigations relating to the fresh waters the one of 
most direct importance has probably been the study of the salmon 
rivers of Alaska with respect to the natural history of the salmon, the 
threatened depletion of the schools by the destructive methods of cap- 
ture now in use, and the measures necessary to preserve this extensive 
food supply. The observations were made on Kadiak and Afognak 
islands, and on Wood River at the head of Bristol Bay. The fresh- 
water systems have also been examined in eleven different States and 
Territories, as follows: The Yellowstone National Park, Colorado, Utah, 
Missouri, Arkansas, lowa, Wisconsin, Indiana, Ohio, Kentucky, and 
