674 U. S. BUREAU OF FISHERIES 
expense? Perhaps by planting 10,000 fry, or 5,000 fingerlings, or so on—who 
knows? It is a problem that has direct economic bearing on the conduct of 
the hatchery. It is an expensive proposition to rear trout to the larger sizes. 
The mortality is heavy. Food costs are large. The expense of planting these 
fish is heavy. The tendency in the East is to plant larger and larger fish, 
because they believe (and I think there is some ground for that belief) that 
the larger the fish, the better the results that you get. Whether this is sound 
from a purely economic standpoint, I do not know. In some places they are 
planting trout 8 and i2 inches long, and the angler comes along the next day 
and catches them. 
I shall now pass to pond culture, which is quite a different problem, in many 
phases, from that of trout, because the methods used are necessarily very 
different. Pondfishes are such fishes as the bluegill sunfish, the bass, and the 
crappie. We must produce spawning grounds and allow them to live under 
normal conditions. Natural conditions are desirable if we are to get as many 
fry and fingerlings as possible. Experimental pond work has been taken up 
only very recently. Last year the Fairport station had 21 ponds, the facilities 
of which were devoted to experimental purposes. Mr. Lord, who has been 
conducting these experiments, will give more details. I want to state, very 
briefly, the general program on which we are working. One of the first prob- 
jems, and one that I consider of major importance, is the production of food for 
these fish. So far, we have not attempted to use artificial food. I think we will 
modify this when we have gone a little further into our operations. What we 
are trying to do is to produce the maximum amount of fish flesh per acre. We 
must use much the same methods that the agriculturist uses in producing crops 
on land. As you are probably aware, it has been found that we can produce 
as much flesh food, per acre of water, as we can on land, and possibly can do 
even better than that. Our pond experiments in the production of food revolve 
around fertility. Of course, this brings up the problem of the best fertilizer, the 
time when it should be applied, and so on. There are a multitude of problems, 
all of which we know comparatively little about. In connection with this 
problem is the study of forage fishes. By forage fishes we mean small fishes, 
such as minnows, on which the game fish feed. This is an immensely important 
problem and one on which very little has been done. During the past year we 
have been working with a number of species of fish at the Fairport laboratory 
and we have obtained some very encouraging results. I think there are great 
possibilities in the development of the use of forage fishes in pond culture. 
Then, of course, just as in the case of the trout, we are undertaking investiga- 
tions of parasites and diseases of these fish. These problems are not so serious 
as in the case of the trout, because the fish are not so crowded, but they will 
probably become more so in the near future. Already we have gotten quite a bit 
of publicity with regard to the parasites that occur in bass. One important 
parasite is a tapeworm, known as Proteocephalus ambloplites, which occurs in 
the bass. The adult stage does not do much harm, but the invasion of the 
parasite in the larval stage produces serious results, for it migrates into the 
connective tissues. It seems to have a special liking for the gonads, both in the 
male and the female. The result is that the fish are virtually sterile. They may 
appear to be all right in every respect, but they do not produce young. This 
parasite was first found in hatchery fish at the Neosho (Mo.) station, and since 
then has been found to be quite widespread. It probably was introduced into 
our hatcheries in fish shipped from Lake Erie. This illustrates one of the 
handicaps under which the fish-culturist is laboring because it is necessary, in 
order to get a supply of fish for the hatcheries, to ship them very long distances. 
Lake Erie was a common source of supply for the smallmouth bass, particularly, 
and as a result this parasite has been introduced widely throughout the country. 
This parasite probably is the most serious enemy with which we have to deal, in 
connection with bass, at the present time. Here, again, we are planning to start 
some selective breeding experiments. This work will involve difficulties that are 
not present in the case of the trout because the pondfishes are not so closely 
under our control. I believe, however, that it is going to be possible to produce 
superior strains of fish, which will be better adapted to hatchery conditions. 
Furthermore, more attention should be paid to the strains of wild fish that we 
are introducing into our hatcheries. If possible, we should use only superior 
strains of wild fish in building up a brood stock. 
Another problem that we are intending to undertake this year is to look 
into the advisability of using fish in pond-cultural work which have not yet 
been utilized for this purpose. There is an urgent demand for a fish that 
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