THE SMELTS 
311 
contained one smelt. On June 27, 1911, a “cusk” 22% inches long contained two 
heads of large smelt, portion of the body of a large smelt, two partly digested small 
smelts, and two small fresh-water sculpins (Cottus) ; also a nymph of a stone fly. 
This fish was taken in about 70 feet of water. 
PARASITES 
Besides the previously mentioned vertebrate enemies, there are invertebrate 
animals that are regarded as more or less inimical to smelts. Concerning inverte- 
brates that are actually harmful to smelts very little is known. Parasites of fishes 
have received some study by various specialists, but very little attention has been 
given those of the fresh-water smelt. Of those known to infest the smelt none has 
yet been shown to be actually injurious under ordinary conditions. The most con- 
spicuous of fresh-water smelt parasites is a small degenerate crustacean known as a 
copepod. However, this animal is not peculiar to the smelt but has been observed 
attached to the gills, fins, or skin of other fishes. 
To the gills, of some smelts taken by hook and line from Swan Lake, Me., and 
sent in by A. D. Merrill in May, 1898, many parasitic copepods were found to be 
attached; and on various occasions the present writer collected many dead and dying 
smelts on the surface of Sebago Lake. Thirty of these fish were from 4% to 5% 
inches long and were more or less fungused. Parasitic copepods were numerous on 
all of them, principally upon the gills but occasionally elsewhere. Some of these 
copepods were submitted to Prof. Charles Branch Wilson for identification, and from 
him the following letter was received : 
I find the parasites on the gills of the smelt taken from Sebago Lake to be Ergasilus cen- 
trarchidarum Wright. They do not usually occur in sufficient numbers to injure their hosts, but 
under favorable conditions may breed rapidly enough to destroy the fish. The physical condition 
of the fish has much to do with the effect produced upon it by the parasites, hence the latter pro- 
duce pernicious effects during the fish’s breeding season, when it becomes thoroughly exhausted 
and weakened. The minnows and darters usually catch enough of the larvae of the parasites dur- 
ing their free-swimming period to keep them within due bounds, the small top minnow being espe- 
cially serviceable in this respect. This is the same form that was found at Culver [Indiana] last 
summer [1906], and it probably infests the fish in all fresh-water ponds and lakes to some extent. 
The other parasites of the smelt that have received scientific notice are "worms.” 
The first to attract attention is a small leech, which in connection with the smelts 
up to the present time has been found in Lake Champlain. Cheney (1895, p. 229), 
writing concerning the icefish of Lake Champlain, said: 
I found that the smelts caught at Port Henry had an attachment which was entirely new to 
me, in the form of a sucker. The sucker was very like a worm, a little thicker than an ordinary 
knitting needle, dark gray, somewhat mottled in color, and they seemed to be jointed in the body. 
They were from one to two inches in length, and the sucker which occupied one end of the body 
looked like the end of a tin horn reduced in size. These suckers could be seen about the holes in 
the ice after the fishermen had removed them from the smelts, wriggling about on the ice or in the 
icy water. They made no mark on the smelt, nor did they do them any apparent harm, and they 
were entirely new to me. 
Both at Port Henry and at Presberry Point on February 16, 1911, the present 
writer found some smelts infested more or less by these leeches. Sometimes a bunch 
