DISEASES OF MARINE FISHES
19
The same condition and parasite have been reported in Thyrsites ntun
from Australia by Johnston and Cleland (1910) and Willis (1949).
Milky ” flesh deteriorates rapidly after the fish is caught, probably
due in part to a proteolytic enzyme secreted by the parasite, as postulated by Willis. In South African waters, Davies and Beyers (op. cit.)
found that three-fourths of the John Dory and stockfish were infected
with Kudoa thyrsites. A quarter of all John Dory were too heavily
infected to be suitable for filleting. The same parasite occurred in 5 %
of Australian barracouta (Roughley, 1951).
The flesh of clupeoid fishes is often parasitized by Myxosporidea
which produce opaque white cysts and necrotic areas (Fig. 5). A
Chloromyxum occurs in the pilchard, Sardinops ocellntn, from South
Africa (Rowan, 1956). Juvenile Atlantic herring, Clupen harengus,
menhaden, Brevoortia fyrannus, and blueback herring, Alosa aestivnlis
(Mitchill) from the Atlantic coast of North America are often parasitized by Kudoa (=Chloromyxum) clupeidae (Hahn, 1918 ; Meglitsch,
1947 ; Sindermann, 1961b). Several authors (Tyzzer, 1900 ; Linton,
1901 ; Sindermann, 1957) have noted that the parasite occurred only
in smaller and younger members of the host species. As many as 75%
of 1-year-old Atlantic herring from certain parts of the U.S. (Maine)
coast were parasitized, but adults were not infected. Linton speculated
that there were fewer infections among older fish because the vitality
of the diseased fish was so impaired that they fell victim to predators
in larger proportional numbers than did healthy fish. It seems equally
likely that invasion occurs early in the life of the host, that spores
mature and escape from cyst areas, and that evidence of disease is
absent by the time the host reaches maturity.
Among the anadromous fishes, the myxosporidean Henneguya
salminicola Ward invades the flesh of several species of Pacific salmon,
producing opaque white cysts described as “ tapioca disease ” (Fish,
1939). Spores of the parasite have also been seen in milky necrotic
pockets in salmon from the eastern Pacific (Patashnik and Groninger,
1964). Similar pathological conditions and high prevalences have been
described in salmon from the western Pacific by Akhmerov (1955).
It can be seen from even a brief review that muscle-inhabiting
Myxosporidea are of world-wide distribution and economic significance.
This is particularly true of members of the genus Kudoa which was
created by Meglitsch (1947) to include species removed from the genus
Chlorom y x u m that are histozoic with quadrate or stellate spores,
These species are associated with necrosis of the flesh of living fish,
and with rapid post-mortem deterioration and liquefaction.
The gall-bladder-inhabiting Myxosporidea, of which there are many
19
The same condition and parasite have been reported in Thyrsites ntun
from Australia by Johnston and Cleland (1910) and Willis (1949).
Milky ” flesh deteriorates rapidly after the fish is caught, probably
due in part to a proteolytic enzyme secreted by the parasite, as postulated by Willis. In South African waters, Davies and Beyers (op. cit.)
found that three-fourths of the John Dory and stockfish were infected
with Kudoa thyrsites. A quarter of all John Dory were too heavily
infected to be suitable for filleting. The same parasite occurred in 5 %
of Australian barracouta (Roughley, 1951).
The flesh of clupeoid fishes is often parasitized by Myxosporidea
which produce opaque white cysts and necrotic areas (Fig. 5). A
Chloromyxum occurs in the pilchard, Sardinops ocellntn, from South
Africa (Rowan, 1956). Juvenile Atlantic herring, Clupen harengus,
menhaden, Brevoortia fyrannus, and blueback herring, Alosa aestivnlis
(Mitchill) from the Atlantic coast of North America are often parasitized by Kudoa (=Chloromyxum) clupeidae (Hahn, 1918 ; Meglitsch,
1947 ; Sindermann, 1961b). Several authors (Tyzzer, 1900 ; Linton,
1901 ; Sindermann, 1957) have noted that the parasite occurred only
in smaller and younger members of the host species. As many as 75%
of 1-year-old Atlantic herring from certain parts of the U.S. (Maine)
coast were parasitized, but adults were not infected. Linton speculated
that there were fewer infections among older fish because the vitality
of the diseased fish was so impaired that they fell victim to predators
in larger proportional numbers than did healthy fish. It seems equally
likely that invasion occurs early in the life of the host, that spores
mature and escape from cyst areas, and that evidence of disease is
absent by the time the host reaches maturity.
Among the anadromous fishes, the myxosporidean Henneguya
salminicola Ward invades the flesh of several species of Pacific salmon,
producing opaque white cysts described as “ tapioca disease ” (Fish,
1939). Spores of the parasite have also been seen in milky necrotic
pockets in salmon from the eastern Pacific (Patashnik and Groninger,
1964). Similar pathological conditions and high prevalences have been
described in salmon from the western Pacific by Akhmerov (1955).
It can be seen from even a brief review that muscle-inhabiting
Myxosporidea are of world-wide distribution and economic significance.
This is particularly true of members of the genus Kudoa which was
created by Meglitsch (1947) to include species removed from the genus
Chlorom y x u m that are histozoic with quadrate or stellate spores,
These species are associated with necrosis of the flesh of living fish,
and with rapid post-mortem deterioration and liquefaction.
The gall-bladder-inhabiting Myxosporidea, of which there are many