Artificial propagation of marine species by United States. Bureau of fisheries

Author:United States. Bureau of fisheries. [from old catalog]
Language: eng
Format: epub, pdf
Tags: Fish culture
Publisher: Washington, Gov't print. off.
Published: 1904-03-25T05:00:00+00:00

218 REPORT OF COMMISSIONER OF FISH AND FISHERIES.

inclement and changeable weatber occurs, and is necessarily somewhat limited in extent by uncontrollable physical and other conditions.

During the fiscal year 1895-9G, the collections of flatfish eggs numbered 11,008,000, which yielded 8,472,000 fry; in the year 1896-97 84,591,000 eggs were taken, from which 64,095,000 fry were hatched.

The flatfish from which eggs are obtained are very plentiful during February in the Woods Hole region, being found on sandy or hard clay bottom, and taken in fyke nets set in water from 6 to 14 feet dee]}. As many as GO to 70 fish are sometimes taken at one lift of a fyke net, but as a rule not more than two or three of this number are gravid fish. These nets are usually some distance from the station, and the fish are carried to the hatchery in transportation cans, six or eight being put in one can. In some cases this trij:) is made by water in a sail or row boat, while at other times it is made overland by team. The fish are often carried 10 or 12 miles without change of water and without apparent injury. A few are caught while the water temx^erature is as low as 33° F., but they are more numerous after the tem])erature reaches 34° or 35° F. On arriving at the station the fish are \)x\t into wooden tanks supplied with constantly changing water, and here they are held until ripe. It is customary to put both males and females in the same box or tank. The fish are examined daily and the eggs are taken from all which are found to have ripened, the stripped or spent fish being released.

The eggs of the flatfish are quite small, there being 30 in a linear inch. Unlike the eggs of the cod, haddock, mackerel, and other marine fishes, they do not float, but sink to the bottom of the vessel in which they are held. They are not so heavy as those of the lobster, and a slight current causes them to rise and carries them to a i)oint where there is still water, when they again go to the bottom. When first deposited, the eggs are very adhesive and stick together-in one mass or in clusters of different sizes. This adhesiveness is overcome, in a measure, by thoroughly washing them, and, as this force gradually weakens as the eggs become older, usually nearly all the eggs are separate when they begin to hatch. The use of dry powdered starch is very eflective for this purpose; this mixes readily with the salt water and admirably overcomes the glutinosity of the eggs. Its action is purely mechanical.

In stripping, it is customary to fill a Chester jar with water and place inside the jar a bag made of cheese-cloth, into which the eggs are allowed to fall. The fish is grasped by the head with the left hand, the mouth being in the palm of the hand, and the edge on which the vent is located turned from the spawn-taker.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.