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 

 Siluridse (including the catfishes), for example, are very much more 

 numerous on the Pacific coast than on the Atlantic. The Scaridee 

 (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 Scaridse 

 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. E. Crawford, scientific assistant. 



There are apparently two races of herring {Clupea pallasii), 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 the outer 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 



