46 BULLETIN 2, U. S. DEPARTMENT OF AGRICULTURE. 
is produced in large amount by the extensive fisheries on the Great 
Lakes, but there again it is so badly scattered that its treatment to 
any considerable extent is impracticable. These sources then scarcely 
can be looked to for increasing the Nation's output in fish scrap. 
Among the so-called waste fish, fish commonly regarded as unfit 
for food and applied to no other use, the dogfish are perhaps most 
numerous in coastal waters and most easily caught. The interest of 
the various fisheries rather demand that the number of dogfish be 
reduced; and the experience in Canada, where through Government 
initiative they are being converted into fertilizer, shows that they 
are a potentially large source of fish for fish-scrap purposes, and in 
their utilization one reasonably may expect a development of the fish- 
scrap industry. 
This discussion has been confined to conditions as they have been 
observed on the Atlantic coast and do not apply at all to the Pacific 
coast. The salmon canneries on the Pacific coast produce very large 
amounts of refuse, representing, roughly, 30 per cent of the " round " 
weight of the salmon taken. The salmon-canning industry by no 
means is confined to the States, but is carried on quite extensively 
in southeastern and southwestern Alaska. A considerable amount of 
the refuse now produced in the States is made use of in the prepara- 
tion of fertilizers, a practice which is on the increase. In Alaska 
practically none of the refuse is saved. A discussion of the salmon- 
cannery waste is not in place in this report, since it is the intention 
of this bureau to conduct an investigation during the coming summer 
with a view to the more complete utilization of this material for 
fertilizer purposes. Since nature has provided an abundant growth 
of the self -perpetuating and highly potassic kelp in the neighbor- 
hood of many of the canneries, it is hoped that the two materials 
can be combined and a fertilizer, containing the three most desired 
ingredients — nitrogen, phosphoric acid, and potash — be manufac- 
tured with profit. 
OILS. 
DEVELOPMENT. 
Fish oils for many years have been among the important products 
taken from the sea. The whale constituted the first important source 
of the so-called fish oils and to-day yields about 3,000,000 gallons 
annually. In addition to these, other aquatic animals, such as the 
porpoise, the blackfish, seals, walrus, and the livers of cod, have 
been made a fruitful source of the animal oils. 
Menhaden oil, the true fish oil, and by far the most important oil 
produced on the Atlantic coast of the United States, first appeared 
on the market in considerable quantity in the early sixties. The 
large prices obtained in the early days of the industry led to a rapid 
