Artificial Propagation of Sturgeon
Artificial Propagation of Sturgeon – A number of attempts have been made in the United States at various times to propagate the sturgeon by the artificial manipulation of the If’s, but in every instance, they have been rendered practically null by certain unusually persistent difficulties.
An account of the efforts may be of interest and value, particularly in view of the fact, as appears from the accompanying; ])uper of Prof. N. A. Borodin, formerly connected with the Russian department of agriculture, that most of these obstacles were overcome in the course of some experimental work performed under his direction as chief specialist in fish culture in that department.
The first attempt at sturgeon propagation by a representative of the United States Government was in 1888 at Delaware City, Del., In the course of an investigation of the sturgeon fishery by Dr. John A. Ryder (Bulletin, U. S. Fish Commission, 1888), but experiments along that line had been conducted by Seth Green at Xue Hamburg, N. as early as 1875 and were described by him in his book entitled ” Fish Hatching and Fish Catching,” published at Rochester in 1879.
The eggs for the experiment at Delaware City were obtained from fish landed for the market. A number of such fish were examined, but of the various lots of eggs secured only one squall lot was successfully hatched. In this instance they were taken by opening the female fish, and after fertilization had been accomplished by the application of milt secured in the customary manner, the eggs were spread in a single layer over the cheesecloth bottom of shallow boxes and anchored in a small sluiceway where there was a constant current of water.
The same drawbacks—viz; difficulty in finding ripe eggs and milt at the same time, imperfect aeration of the eggs during the incubation period, and the unusual tendency of the eggs to develop fungus — were again encountered in the course of a second attempt to propagate sturgeon at Delaware City by Dr. Bashford Dean in 1893.
The work of that year disclosed the feasibility of using as a fertilizing medium milt secured by the removal of testes from male fish which were not sufficiently matured to void the secretion by the application of external pressure.
The milt was separated from the cut testes by straining through a coarse cloth and proved just as effective as that taken from live fish, even after being held for several minutes in the rubber-bulb container.
In an effort to overcome past troubles, the style of hatching apparatus was changed. The eggs were spread evenly under water on shallow trays in boxes whose sides and bottoms were covered with metal gauze.
The necessity for quick handling soon became apparent, as the viscid nature of the eggs causes them to cling so firmly to any surface with which they come in contact that they are invariably injured in the attempt to loosen them, and it was found that if not placed on the trays within 10 or 15 minutes after being fertilized they would form into a gluelike mass, which speedily became compact and hard.
After allowing sufficient time for the eggs to become firmly attached, the trays containing them were fitted into the boxes and anchored in various places in the riverbed.
By the end of the second day thereafter the eggs in the boxes, which had been moored in marginal waters having a sluggish current and carrying much silt, were found to be entirely enveloped in fungus and dead.
Those placed where the water current was strong and comparatively free from sediment had sustained a loss of 60 percent by the close of the fifth day from the same cause, while those which had been installed in a strong current in salt water showed practically no fungoid growth and were hatched in good condition.
In the spring of 1890 Frank N. Clark, superintendent of the Northville (Mich.) station, made preparations for the collection of sturgeon eggs at Fox Island, Mich., and under his direction 142 female and 32 male fish were examined between May 26 and June 14. Examination showed that 23 of the females had already spawned, 98 were very immature, the eggs in 6 were nearly ripe, and 5 were in spawning condition. Of the males 21 were hard, 2 almost mature, and 9 entirely so.
In all, 20^00 eggs were secured and fertilized by cutting open and squeezing the milt sacs after moistening them with water. Much difficulty was experienced from adhesion, three hours of constant stirring being required to break up and separate the bunches of eggs.
Ninety-five per cent of them were developed to the eyed stage, but shortly afterwards a growth of fungus began spreading in the floating boxes in which they were being incubated, and, as a result, very few of the eggs hatched. Had it been possible to incubate them in whitefish jars it is estimated that at least 85 per cent would have been saved.
In the course of experimental work conducted in 1901 on the Missisquoi and Lamoille Rivers, tributary to Lake Champlain, efforts were made to hold green sturgeon in artificial enclosures for ripening.
These’ efforts proved utterly futile, as in every instance the eggs caked together in a hard mass and development was arrested. Notwithstanding the great difficulty experienced in securing ripe eggs and milt together, 1,500,000 eggs were taken and fertilized, and their viscosity was effectively overcome by the method that is employed for the separation of pike-perch eggs.
They were then successfully hatched in McDonald jars, the incubation period being about six days in a water temperature of 05° F. The fish from which they were secured were taken especially for work, and their violent struggles when cingulid frequently resulted in the loss of many of their eggs.
Such losses were unavoidable, as it was possible to distinguish a ripe female only when the eggs ran from it after it was
taken from the water.
In 1911 experimental sturgeon propagation was undertaken in Minnesota in the Lake of the Woods region. In advance of the season’s run of fish an enclosure large enough to hold; iOS adult sturgeon was constructed in Rainy River, and a hatching apparatus of sufficient capacity to accommodate 3.000.000 eggs and fry was set up in a convenient building.
During the spring IG sturgeons were captured in a pound net and transferred to the pen. Though held for several months under apparently favorable conditions, they failed to mature, and in the following October they were released without having produced any eggs. Another trial was made in the following year with the same results.
From the observations made it was concluded that sturgeons do not spawn until the water has attained a temperature of 60° F. that the eggs do not ripen in fish held in confinement; and that unless? Nearly ripe males are available when the eggs are taken no results can be expected.
The spawning season at the various grounds has always been short, seldom exceeding three or four days. It is believed that jars similar to those used in the propagation of whitefish and pike perch are the most suitable form of equipment for the
development of sturgeon eggs.
Also Read Part 2. Artificial Propagation of Sturgeon in Russia.
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