16 U. S. BUREAU OF FISHERIES. 
for this may be found by consideration of the habits of the species 
of those families which do not conform to the usual rule. The 
Siluride (including the catfishes), for example, are very much more 
numerous on the Pacific coast. than on the Atlantic. The Scaride 
(including the parrot fishes and viejas), on the other hand, are much 
more numerous on the Atlantic than on the Pacific. It is well known 
that most catfishes frequent water with soft or muddy bottom. The 
Pacific coast of Panama has many large mud flats partly or wholly 
exposed at low tide but flooded during high water. The Scaride 
prefer rocky bottom, and especially coral reefs, which are large and 
extensive on the Atlantic side. These conditions undoubtedly pre- 
vailed, in part at least, before the last passageway between the two 
oceans was closed, and it is probable that these families had already 
sought out regions best suited to their particular needs. 
The commercial fisheries of Panama are still largely undeveloped. 
The possibilities for profitable fisheries appear to be especially good 
on the Pacific coast, but apparently less promising on the Atlantic 
side of the Isthmus. The people of the Isthmus are less wasteful of 
fishes than the people of the United States, as nearly all species of 
fish taken, including sharks and skates, are utilized as food. 
PACIFIC HERRING. 
During the year the Bureau issued a memorandum dealing with 
the distribution, migrations, sizes, and spawning times and places of 
the Pacific herring in southeast Alaska and British Columbia, based 
upon the observations of D. R. Crawford, scientific assistant. 
There are apparently two races of herring (Clupea pallasi), one 
of which resides in the bays and inner waterways along the coast 
from Puget Sound northward to British Columbia and southeast 
Alaska. The other, which is composed of larger individuals, passes 
along theouter coasts where it is taken off Vancouver Island in June, 
July, and August. ; 
The smaller race of herring is found to be sexually mature in the 
summer, but no milt or roe is found during the winter. Sexually 
mature individuals vary in size from 6 to 10 inches. The probable 
spawning time is late summer or early fall. The larger race of her- 
ring reaches sexual maturity in the fall and winter, the individuals 
varying in size from 9 to 12 inches or longer. The probable spawn- 
ing time is winter or early spring. 
USE OF FISH IN COMBATING MALARIA. 
COOPERATION IN ANTIMALARIA CAMPAIGN. 
Investigations of fishes in relation to mosquito control were con- 
ducted during the mosquito-breeding season of 1920 by Samuel F. 
Hildebrand, scientific assistant, working in cooperation with the 
United States Public Health Service. In the spring and early part 
of the summer Mr. Hildebrand inspected various localities in 12 
Southern States where malaria-control work was to be undertaken. 
Suggestions were offered concerning the employment of fish for the 
control of the mosquito, and the waters suitable for fish control were 
pointed out to the officers in charge. The result of these inspections 
