File:Annual report of the Commissioner of Fisheries to the Secretary of Commerce for the fiscal year ended (1918) (19357136772).jpg

Title: Annual report of the Commissioner of Fisheries to the Secretary of Commerce for the fiscal year ended ..
Identifier: annualreportofco1918uniteds (find matches)
Year: 1913 (1910s)
Authors: United States. Bureau of Fisheries
Subjects: Fisheries
Publisher: Washington : G. P. O.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
FISHES IN RELATION TO MOSQUITO CONTROL. 5 there is not much vegetation, but considerable wave action, and as a rule these ponds are not well suited to prolific mosquito breeding. GAMBUSIA AFFINIS AND THE GENERAL PLAN PURSUED IN TESTING ITS VALUE IN ANTIMOSQUITO WORK. Gambusia was selected for the present tests because, first, it seeks its food at the surface, which appears to make it especially suitable for antimosciuito work; second, it lives and thrives imder a large variety of conditions and especially in water suitable for the support of mosquito larvae; third, it proved to be quite conimon in the extra- cantonment zone and adjacent territory; fourth, it is very prolific; and fifth, its usefulness in destroying mosquito larvae in aquaria and fomitams was already well known. This fish does not lay eggs, but gives birth to well developed and very active yomig. It, therefore, requires no special environment, as most other fishes do, for depositing and hatching the eggs. Young
Text Appearing After Image:
Gambusia affinis (female). of the season were noticed for the first time on April 24, and during the latter half of October a gravid female stiU occasionally appeared among collections. The author,** working with Gambusia at Beau- fort, N. C, found that it breeds throughout the summer and that a new brood is produced at intervals of about one month or six weeks. It was observed that a single female gave birth to six broods of young during a single season. The number of young produced at one time appears to bear a direct relation to the size of the female, a large female producing many more young than a small one. The largest brood observed by the writer numbered 63, but Smith,^ working with fish from the Potomac River, found 100 in a single brood. The young are approximately one-half inch in total length when born; they are very active and are apparently much better adapted to begin, the struggle for an existence than most fish hatched from eggs. They, in fact, are ready to begin the work of destroying mosquito larvae at once, for the writer has seen them attacking and eating small and even medium-sized mos(juito larvae in aquaria before they were a day old. Gambusia gams growth rapidly and the earliest broods of the season, born in April and May, become a Hildebrand, Samuel F., Report, U. S. Commissioner of Fisheries, Appendix VI, 1917, p. 6. & Smith, H, M., Science, n. s.. Vol. XXXVI, 1912, p. 224.

Note About Images