A very limited trial of fish dried without salt or smoke indicates that it is, when free from oil, a very superior article; it has, of course, to be moistened before using. Its preparation presents some difficulties, but in winter it is easily effected by impaling the whole fish on sticks and hanging them up, (after the manner of alewives or herring in a smokehouse) under a roof where they will be protected from rain without hindering the circulation of air; in this way we have dried many flounders and other refuse fish from the smelt fisheries, which are conducted with bag nets in the vicinity of Bucksport.
Doubtless a centrifugal drying machine might be successfully used for this purpose in summer. Pickled alewives, freshened out in water, have been found to answer fairly well, when other materials are lacking, at least to give growth to maggots otherwise started. Fish pomace has not thus far given satisfaction, but seems worthy of further trial.
It is commonly necessary to expose meat but a single day to obtain sufficient fly sp.a.w.n; the larvae are hatched and active the next day, except in cool weather, and they attain their full growth in two or three days. To separate them from the remnants of food and other debris was at first a troublesome task. It is now effected as follows: the meat bearing the fly sp.a.w.n is placed on a layer of loose hay or straw in a box which has a wire-cloth bottom, and which stands inside a slightly larger box with a tight wooden bottom. When full grown the maggots work their way down through the hay into the lower box, where they are found nearly free from dirt.
When young salmon or trout first begin to feed they are quite unable to swallow full-grown maggots. Small ones are obtained for them by putting a large quant.i.ty of fly sp.a.w.n with a small quant.i.ty of meat, the result being that the maggots soon begin to crowd each other and the surplus is worked off into the lower box before attaining great size. No attempt is, however, made to induce the young fish to swallow even the smallest maggots until they have been fed a while an chopped liver.
In the above methods maggots are produced and used in considerable numbers, sometimes as many as a bushel in a day. Through September, 1893, although the weather and some other circ.u.mstances were not very favorable, the average daily production was a little over half a bushel.
They are eagerly eaten by the fish, which appear to thrive on them better than on dead meat. Having great tenacity of life, if not snapped up immediately by the fish they remain alive for a day or two, and, as they wriggle about on the bottom, are almost certain to be finally eaten; whereas the particles of dead flesh that fall to the bottom are largely neglected by the fish and begin to putrefy in a few hours. In the fish troughs there are, therefore, certain gains in both cleanliness and economy from the use of maggots which may be set down as compensating the waste and filthiness of the fly-house.
As the growth of maggots can be controlled by regulation of the temperature, it is possible to keep them all winter in a pit or cellar, and advantage is taken of this to use them during winter as food for fish confined in deep tanks not easily cleaned.
The offensive odors of decaying flesh may be largely overcome by covering it, on putting it away in the boxes, after the visits of the flies, with pulverized earth, and it is not improbable that by this or some other method the business may be made almost wholly inoffensive, but in its present stage of development it is too malodorous to admit of practice in any place where there are human habitations or resorts within half a mile of the spot where the maggots are grown.
As remarked above, only flesh-eating maggots have yet been tried. It would be well worth while to experiment with the larvae of other species, such as the house fly, the stable fly, etc. There is also a white maggot known to grow in heaps of seaweed. Should the rate of growth of either of these species be found to be satisfactory they might be subst.i.tuted for the flesh maggots with advantage.
Occasional use has been made of fresh fish for direct feeding. When thrown into the water after chopping it breaks up into fibers to such an extent that it is not very satisfactory, and I do not suppose we shall use it in the future, unless in a coa.r.s.ely chopped form for the food of large fish. A few barrels of salted alewives have been used, and if well soaked out and chopped they are readily eaten by the larger fish and can be fed to fry, but are less satisfactory with the latter, and like fresh fish they break up to such an extent that they are only to be regarded as one of the last resorts.
Fresh-water mussels have been occasionally gathered in the lake close to the station when there has been a scarcity of food. Those employed belong almost wholly to a species of Unio which abounds over a considerable area of soft bottom, under a depth of 2 to 10 feet of water. Many were taken with a boat dredge; more were scooped up with long-handled dip nets of special construction. Finally a wide, flat dredge was made, to be drawn by a windla.s.s on the sh.o.r.e and manipulated by means of poles from a large boat.
When needed for food the mussels were opened with knives--a great task--and chopped. The meat is readily eaten by all fishes, and appears to form an excellent diet. Being more buoyant than any other article tried, it sinks slower in the water and gives the fish more time to seize it before it reaches the bottom, a consideration of considerable practical importance. The labor involved in dredging and sh.e.l.ling is a serious drawback, but were the colonies of unios sufficiently extensive or their reproduction rapid enough to warrant expenditure of time in experimentation; improved methods might be devised, which would put this food-source on a practicable basis.
During the seasons of 1886 and 1888 some use was made of mosquito larvae. Near the station is an extensive swamp where these insects breed in great numbers. From the pools of water the larvae were daily collected by means of a set of strainers specially devised for this use. Barrels filled with water were also disposed in convenient places near the rearing troughs, and were soon swarming with larvae from the eggs deposited by the mosquitoes on the surface of the water. When near the completion of their growth, which was only some ten days after the deposit of the eggs, the larvae (or pupae) were strained out and fed to the fish. No kind of food has been used this station that has been more eagerly devoured, and so far as our observation has gone no other food has contributed more to the growth of the fish; indeed, I am inclined to put them at the head in both respects. It was found, however, that the time expended in collecting them was out of all proportion to the quant.i.ty of food secured, and pending opportunity for further experiment their use was discontinued.
I think it quite possible that an arrangement might be devised whereby the greater part of the labor might be saved. Perhaps a series of breeding tanks arranged in proximity to the fish troughs, into which the water containing the larvae might be drawn when desirable by the simple opening of faucet, would solve the problem.
Various methods of serving the food have been tried, but at present everything is given with a spoon. The attendant carries the food with the left hand--in a 2-quart dipper if chopped meat, in a larger vessel if maggots--and, dipping it out with a large spoon, strews it the whole length of the trough, being careful to put the greater portion at the head, where the fish nearly always congregate. Finely chopped food, for very young fish, is slightly thinned with water before feeding. At one time the finest food was fed through perforations in the bottom of a tin dish; the food was placed in the dish, which was dipped into the water a little and shaken till enough of the food had dropped out of the perforations; this practice was laid aside because it was thought that the food was too much diluted.
In feeding maggots it was, at first, the practice to place them on small "feeding boards" of special construction suspended over the water in the troughs and let them crawl off into the water; but whatever advantage this method may have had in furnishing the meal to the fish slowly was more than counterbalanced by the extra labor of caring for the boards and by the offensive odor, and it was abandoned. For use in feeding fish in a pond a box containing a series of shelves, down which the maggots slowly crawl, was found sufficiently useful to be retained.
It is the common practice to feed all meat raw except the lights, which chop better if boiled first, except also occasional lots of meat that are on the point of becoming tainted and are boiled to save them. All meats fed direct to the fish are first pa.s.sed through a chopping machine. The machine known as the "Enterprise" is the one now in use.
It forces the meat through perforated steel plates. The plate used for the smaller fish has perforations 2 inch in diameter, and for coa.r.s.er work there are two plates 3/16th inch and 3/8th inch, respectively. It is operated by a crank turned by hand.
Food is given to those fish just beginning to eat four times a day (in some cases even six times). As the season progresses the number of rations is gradually reduced to two daily. In winter such fish as are carried through are fed but once a day. The cleaning of the troughs has been a troublesome matter, and the subject of much study and experiment, but nothing more satisfactory has been found than the following practice: The troughs are all to be cleaned daily--not all at one time, but as time is found for it in the intervals of other work.
To facilitate cleaning, the troughs are inclined about 2 inches. The outlet is commanded, as already explained, by a hollow plug.
When this is drawn the water rushes out rapidly and carries most of the debris against the screen. The fishes are excited, and, scurrying about, they loosen nearly all dirt from the bottom; what will not otherwise yield must be started with a brush, but after the first few weeks the brush has rarely to be used except to rub the debris through the outlet screen. Owing to the inclination of the trough the water recedes from the upper end until the fishes lying there are almost wholly out of water, but, although they are left in that position sometimes for 10 or 15 minutes, no harm has ever been known to result.
It has been the common rule at the station to count all the embryos devoted to the process of rearing, either before or after hatching; to keep an accurate record of losses during the season, and to check the record by a recount in the fall. When eggs are counted they are lifted in a teaspoon.
The counting of small fish is effected in this way: The fish are first gathered in a fine, soft bag-net, commonly one made of cheese-cloth, and from this, hanging meanwhile in the water, yet so that the fish cannot escape, they are dipped out a few at a time, in a small dipper or cup, counted, and placed in a pail of water or some other receptacle.
This counting is generally preliminary to weighing, and in this case the fish, after counting, are placed in another bag-net, in which they are lowered, several hundred at a time, into a pail of water which has been previously weighed, and the increase noted. With care to avoid transferring to the weighing pail any surplus water, this is a correct method and very easy and safe for the fish.
In conclusion, I submit some estimates of cost. In September, 1893, we fed fry that were estimated at the close of the month to number 238,300. There were also a few hundred larger fish.
From the known total outlay for food, attendance, and superintendence a suitable allowance is made for the maintenance of the older fish, and the balance is charged to the fry. By this method we arrive at the following results:
Cost...................Total........Per fish.
Food $155.00 $0.00065 Attendance 99.79 .00042 Superintendence 205.96 .00086 Total 460.75 0.00193
Applied to the rearing operations of 1891, a similar calculation gives us this result: The fry that were carried through the season from June to October, inclusive, cost, for food, attendance, and superintendence, $0.0081 each; that is, about four-fifths of a cent each for the term of five months.
ARTICLE VII
NOTES ON THE CAPTURE OF ATLANTIC SALMON AT SEA AND IN THE COAST WATERS OF THE EASTERN STATES
By Hugh M. Smith, M. D., a.s.sistant in charge of Division of Statistics and Methods of the Fisheries.
_Bulletin of the United States Fish Commission_, Vol. 14, Page 95, 1894.
In carrying out its most important function--the maintenance and increase of the supply of food fishes--the U.S. Commission of Fish and Fisheries, in addition to direct efforts to increase the abundance of fishes naturally inhabiting our various rivers, lakes, and coast waters, has given considerable attention to the experimental introduction of fishes into regions or streams to which they were not native.
The wonderful success which has followed the planting of shad and striped ba.s.s fry in the waters of the Pacific coast is well known. The results attending the recent attempts of the Commission to establish a run of salmon (_Salmo salar_) in some of the large rivers of the Atlantic coast have been so noteworthy in the case of the Hudson as to afford reasonable ground for expecting the early inauguration of a regular fishery, should the present rate of increase in the abundance of the fish be maintained. Similar striking results may also be antic.i.p.ated in all the more northern streams of the east coast, including the Housatonic, Connecticut, and Merrimac, in which salmon were at one time found in abundance and are now taken in small numbers, if the ascent of the adult fish to the headwaters for the purpose of sp.a.w.ning is permitted and if sufficiently extensive fish-cultural operations are continued.
The primary purpose of this paper is to record some of the apparent results of salmon propagation in our rivers as shown by the occurrence of the fish at points on the coast or at sea more or less remote from the places where fry have been deposited.
While an interesting and instructive compilation might be made of the instances of the capture of salmon in the Hudson, Delaware, Susquehanna, Potomac, and other rivers in which the fish has been acclimated, such a work is not necessary in view of the notice which has already been accorded the matter in the public press and in the reports of several of the State fish commissions, notably the New York commission.
So much yet remains to be learned regarding the lines of migration of the salmon to and from the rivers, its winter habitat, the existence of an "instinct of nativity" which is supposed to impel the return of the fish to the place where hatched, the extent of the coastwise distribution of salmon originally belonging in a given river, and numerous other practical and scientific questions, that the presentation of any data bearing on the occurrence of the fish outside of the rivers may be regarded as acceptable and timely.
In an interesting article on "Salmon at Sea," communicated to the issue of _Forest and Stream_ for February 18, 1892, Mr. A. N. Cheney, the well-known angling expert and writer on fish-cultural matters, discusses the question of the whereabouts of salmon after they leave the rivers, and quotes the following from a previous contribution by himself on the subject:
"There is a certain mystery about the habits and movements of the sea salmon, after it has left the fresh-water rivers in which it sp.a.w.ns and gone down to the sea, that never has been satisfactorily explained. One theory is that all the salmon of the rivers along a coast may journey down to the sea, and then move ultimately in one great body southward along the coast until they find water of suitable temperature, with an abundance of food, in which to spend their time in growing fat until the sp.a.w.ning instinct warns them to return, when they proceed northward, each river school entering its own particular river as the main school arrives opposite the river month.
"Another theory is that the salmon of each river, as they arrive at its mouth after descending from its headwaters, go out to sea sufficiently far to find the conditions of temperature and food which suit them, and there they remain, separate from the salmon of other rivers, until it is time for them to return to fresh water. Considering the certainty with which the salmon of any particular river return again to the stream of their birth, the latter theory seems the more tenable of the two."
Another object of this paper is to solicit correspondence from fishermen, especially those engaged in the coast and offsh.o.r.e fisheries, concerning the circ.u.mstances of the capture of salmon in their nets, and to bring to their attention the opportunity they will thus have of increasing the knowledge of the movements of the salmon, of aiding in the determination of the results of fishcultural operations, and of ultimately if not immediately benefiting themselves by supplying information that will conduce to the most effective application of artificial methods.
To this end it is the intention to send the paper to fishermen engaged in the mackerel, menhaden, and other sea fisheries, and to operators of pound nets, traps, and other sh.o.r.e appliances, with the hope that instances of the capture of salmon may be communicated to this Commission and notes on the size, condition, movements, etc., of the fish be furnished.
To aid in the identification of the salmon when caught by fishermen who have not previously met with the fish, a figure is presented.
In this connection mention may be made of the chinook or quinnat salmon of the Pacific coast (_Oncorhynchus chouicha_), fry of which have been extensively planted in eastern waters by the U. S. Commission of Fish and Fisheries. Up to and including the year 1880, about 12,000,000 fry were deposited in rivers and other waters tributary to the Atlantic.
While a few relatively large examples have been taken, this office has no information to show that the attempts to acclimate this species on the Atlantic coast have as yet been successful. In 1891 a few thousand yearling salmon were placed in New York waters tributary to the sea.
The possibility of the survival and growth of some of these and of the large early colonies prompts this reference to the matter and suggests the publication of the accompanying figure of the species, to afford a basis for distinguishing the two kinds of salmon, which closely resemble each other. To further aid in the identification of the two species the following key has been prepared:
Rays in a.n.a.l fin, 9; scales between gill opening and base of tail, 120; branchiostegals (false gill openings), 11 ..........ATLANTIC SALMON.