24
CARL. J SINDERMANN
according to Kudo (1954), and some suggestion of it was found in
Macrozoarces, since many specimens were characterized by immense
numbers of minute infections involving single muscle fibers (Olsen and
Merriman, 1946).
Body
muscles overlying the visceral cavity of the long rough dab, Drepanopsetta hippoglossoides Gill, are invaded by P. hippoglossoideos Bosanquet,
forming cysts up to 10 mm long. Kabata (1959) found the parasite to
be widely distributed in the North Sea. Cod of the Barents Sea were
found to be infected with P. gadi by Polyanski (1955). The parasite
produced large tumors (5 to 8 mm) in the body muscles.
Other species of Plistophora invade the flesh of fish also.
111. OTHER PARASITIC DISEASES
The invasive diseases, as considered in this paper, include those
caused by the larger parasites-those that are non-multiplicative in
the fish host once invasion has occurred. Of primary concern in marine
fishes are the various parasitic worms and the tissue-invading copepods.
Omitted from this discussion are leeches, most ectoparasitic copepods,
parasitic Cirripedia and Isopoda, and lampreys, which, although of
occasional concern, probably do not often exert serious effects on
marine fish populations. Since the worms and copepods are large,
conspicuous and often abundant, they have been observed and studied
extensively.
A. Helminths
The helminths-trematodes,
cestodes, nematodes and acanthocephala-are common parasites of marine fishes. Usually it is as larvae
that the worms are of greatest significance. Adults occur in the digestive
tract, but larvae are usually found in the flesh or in the viscera. The
effects of worm larvae on the host include growth retardation, tissue
disruption, metabolic disturbances, and even death in heavy infestations. Added economic effects include discarding of otherwise edible
fish products, delay in processing operations and loss in oil yields.
1. Trematodes
Adult digenetic trematodes are common in the digestive tracts of
marine fishes. Yamaguti (1958) recognized 367 genera and 1390 species
from fish, but it is as larvae-as migrating cercariae and as metacercariae-that trematodes seem to be of greatest significance to the
fish host. Marine teleosts serve as intermediate hosts for many trematodes, particularly those whose definitive hosts are shore-inhabiting or
fish-eating birds and mammals. Metacercariae of such worms encyst
CARL. J SINDERMANN
according to Kudo (1954), and some suggestion of it was found in
Macrozoarces, since many specimens were characterized by immense
numbers of minute infections involving single muscle fibers (Olsen and
Merriman, 1946).
Body
muscles overlying the visceral cavity of the long rough dab, Drepanopsetta hippoglossoides Gill, are invaded by P. hippoglossoideos Bosanquet,
forming cysts up to 10 mm long. Kabata (1959) found the parasite to
be widely distributed in the North Sea. Cod of the Barents Sea were
found to be infected with P. gadi by Polyanski (1955). The parasite
produced large tumors (5 to 8 mm) in the body muscles.
Other species of Plistophora invade the flesh of fish also.
111. OTHER PARASITIC DISEASES
The invasive diseases, as considered in this paper, include those
caused by the larger parasites-those that are non-multiplicative in
the fish host once invasion has occurred. Of primary concern in marine
fishes are the various parasitic worms and the tissue-invading copepods.
Omitted from this discussion are leeches, most ectoparasitic copepods,
parasitic Cirripedia and Isopoda, and lampreys, which, although of
occasional concern, probably do not often exert serious effects on
marine fish populations. Since the worms and copepods are large,
conspicuous and often abundant, they have been observed and studied
extensively.
A. Helminths
The helminths-trematodes,
cestodes, nematodes and acanthocephala-are common parasites of marine fishes. Usually it is as larvae
that the worms are of greatest significance. Adults occur in the digestive
tract, but larvae are usually found in the flesh or in the viscera. The
effects of worm larvae on the host include growth retardation, tissue
disruption, metabolic disturbances, and even death in heavy infestations. Added economic effects include discarding of otherwise edible
fish products, delay in processing operations and loss in oil yields.
1. Trematodes
Adult digenetic trematodes are common in the digestive tracts of
marine fishes. Yamaguti (1958) recognized 367 genera and 1390 species
from fish, but it is as larvae-as migrating cercariae and as metacercariae-that trematodes seem to be of greatest significance to the
fish host. Marine teleosts serve as intermediate hosts for many trematodes, particularly those whose definitive hosts are shore-inhabiting or
fish-eating birds and mammals. Metacercariae of such worms encyst