File:Cyprinodon variegatus - Annual report of the Commissioner of Fisheries to the Secretary of Commerce (18742276293).jpg

Title: Annual report of the Commissioner of Fisheries to the Secretary of Commerce for the fiscal year ended ..
Identifier: annualreportofco1917unit (find matches)
Year: 1919 (1910s)
Authors: United States. Bureau of Fisheries
Subjects: Fisheries
Publisher: Washington : G. P. O.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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14 MINNOWS GAMBUSIA AFFINIS AND CYPRINODON VARIEGATUS. some of them before they reached the wire screen. Several dissec- tions made on April 17 showed that the ovary of a large female con- tained about 140 well-developed eggs, fiiUy half of which seemed to be of one size and generally nearly mature. To acquire more data on this pomt, artificial spawning was tried with a number of females. The process of stripping, however, involves more handling than the species endures, and none of the females lived to produce more than two sets of eggs. Females of this species may be found in spawning condition as early as the middle of March and as late as October 1. "VMiether the early spawners continue to spawn as late as October or if these late spawners are those that began spawning later in the season is not known. Our aquarium specimen, which was an early spawner, had, under abnormal conditions, spawned out by August 16.
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Tig. i.— Cyprinodon variegatus. Variegated minnow. Young. The feggs of this species are somewhat heavier than salt water. They are spherical in form and about 1 mm. in diameter. Incubation at laboratory temperature occupies five to six days. The newly hatched young are 4 mm. in length (Kmitz, 1916, p. 414). They grow rapidly and by the beginning of August some of the largest are as much as 32 mm. in length. Up to this age the sexes are colored alike and resemble the adult female, but at about this time the young male assumes the adult markings and hereafter it can with difficulty be distinguished from an adult male. My observations show that this is a very prolific species, and its fecundity may be held to explain in a measure its great abundance. It is said to be of some value as an eradicator of mosquito larvae, but its greatest economic importance probably lies in the food it furnishes for larger fishes. In this connection it may be mentioned that observations in the field and dissections made at various times during two seasons strongly

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