Fishery bulletin of the Fish and Wildlife Service - NOAA

56 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE
to become partially embedded in the mesenteries, but the infection never appears to
be serious. Goezia annulata, although comparatively rare, is probably a much more
serious pest. MacCallum (1921: 261) says:
Its mode of living is calculated -to interfere very materially with the function of the stomach,
inasmuch as it burrows under the mucous membrane, in fact excavating in some cases quite a space
where several worms cohabit. . . . There are often several of these neste in the stomach, each
nest may be 30 mm. to 40 mm. across, and as they cause a good deal of swelling and irritation,
they may and do in some cases so restrict the cavity of the host's stomach that its food cannot be
taken in any quantity sufficient to keep it alive. Thus the worms are a very serious menace to
the fish.
This species is not common in striped bass, however, and according to reports is quite
cosmopolitan in its choice of host, having been recorded from many other species of
fish. Trematode infections are probably sufficiently rare in striped bass in their
natural habitat to be of small importance. Nigrelli and Breder (1934) have shown
that many of the Serranid fishes have developed a resistance to Epibdella melleni,
while Jahn and Kühn (1932) noted that ". . . the possibility of the development oi
immunity seems to be more strongly suggested in this family" (Serranidae). Copepod
parasites are also apparently of small consequence to the striped bass.
It is worth mention that a surprising number of striped bass were encountered
in the Thames and Niantic Rivers, Conn., that had cataracts of the eye. These were
found commonly only in the Thames River, where they sometimes reached above 10
percent of the catch by seine. This opacity of the lens was encountered in all degrees
from a slightly cloudy to a dead-white condition. It was almost universally bilateral,
was rare in 2-year-old bass, and more common in the larger sizes. It was equally
common in all months from April to October. A number of dissections under lowpower
magnification failed to reveal any parasites, such as larval digenetic trematodes,
which might reasonably be expected to cause such blindness. Hess (1937) has recently
shown that bilateral cataracts are common in trout in New York State, both in hatchery
and wild stock, and he has proved with rainbow trout (Salmo irideus) ". . . that
cataract in these fish is due to an unbalanced diet." He has been able to demonstrate
that contagious infection, light, and hereditary factors, are not in any way connected
with the production of such cataracts, and that the feeding of trout exclusively on pig
spleen caused a high incidence of cataract; while trout fed with beef liver and heart
never showed any trace of cataract. It seems likely, therefore, that a dietary deficiency
may perhaps account for the high percentage of blind striped bass in the Thames
River. It is interesting in this connection that the extraction of carotene by acetone from
the liver and fatty tissue of blind and normal bass has tended to show less carotene
per gram of tissue in the blind than in the normal individuals, and it is thus possible
that a lack of vitamin A is associated with the dietary deficiency causing cataracts.
It is also of interest that Schultz (1931) has recorded a case of what gave every
appearance of being completely functional hermaphroditism in the striped bass.
This fish was taken in Oregon in May, and the eggs in one half of the gonads measured
about 1 mm. in diameter, close to the size at the tune of spawning (see p. 19), while
the male half of the gonads was apparently developing normally.
DISCUSSION
It has been pointed out that there has been a striking decline in the numbers of
striped bass along the Atlantic coast over long-term periods. (See under section on
fluctuations in abundance of the striped bass, p. 8, and figs. 3 and 4.) The records
show that this decline has been fairly steady from at least as far back as the middle of
the nineteenth century, and perhaps before. They also indicate that it has been
interrupted only by the occasional appearance of dominant year-classes—groups oi
striped bass that were produced in such huge amounts in certain years that they caused
a marked increase in the numbers caught for short periods (see p. 8, et seq.). It is
apparent from the available catch records (see fig. 4), however, that these dominant
year-classes did not bolster the stock for more than a few years, and that their effects
invariably have been short lived. In other words, the surplus created by them was
soon removed, no permanent increase in abundance—and a consequent permanent
increase in catch—resulted, and the decline in numbers of striped bass, although temporarily
interrupted, soon resumed its normal trend.