DISEASES O F MARINE FISHES
29
Mann, 1954) reported disruption of growth as a result of tapeworm
infestation of Baltic Sea turbot, Rhonibus nicrximus (I,.). Fish in their
second year of life v rrc most seriously parasitized and complete
recovery of normal growth rate took several years.
Adult cestodes may occur in significant numbers in the digestive
tract of fishes, although their prevalence in marine teleosts is low in
comparison with that of other helminths. Linton (1941) described
many representatives from the western North Atlantic, and Wardle
(1932, 1935) surveyed the Pacific coast fauna. The Pseudophyllidean
genus Eubothrizcm Bloch (Abothrium Luhe) is common in marine and
fresh-water fishes. Several species occur in the digestive tracts of cod,
haddock, herring and other sea fishes (Nybelin, 1922 ; Sprehn, 1934).
Many other representatives of the Pseudophyllidea occur in teleost
fishes (Wardle and McLeod, 1952), while the order Tetraphyllidea is
well represented among the elasmobranchs (Woodland, 1927; Baer,
1948; Williams, 1968).
3. Nematodes
The nematode parasites of marine fishes have received attention
primarily because certain larvae that infest the flesh and viscera
reduce the commercial value of the host. An outstanding example is
the codworm, PorrocaecunL decipiens (Krabbe). The definitive host is
the harbor seal, Phocn vitulina L., according to Scott (1953), and
larvae occur in the flesh of cod, smelt, plaice, ocean pout and other
species of inshore marine fish (Heller, 1949; Scott, 1950, 1954, 1955).
Larvae may also pass from fish t o fish if infected smaller individuals
(for example smelt) are eaten by cod. Olsen and Merriman (1946)
reported ocean pout from New Brunswick t o be heavily infested-to
the extent that the flesh of some fish had a porous appearance. A
similar parasitization of ocean pout had been described from the same
area 25 years previously (Clemens and Clemens, 1921). Scott and
Martin (1957, 1959) found high prevalence but geographic variations
in infestation of cod from the Canadian Atlantic coast ; infestation
decreased in deeper waters and increased with age of the host. A
survey of Porroeaecum adults in seals (Scott and Fisher, 1958) did not
disclosed a direct distribution relationship with larvae in cod.
Templeman et al. (1057), in an extensive survey of groundfish in
the Newfoundland fishing area, found larval Porrocaecunh in cod, smelt,
plaice, witch flounder (Glyptocephalus cynoglossus (L.) ), haddock and
redfish (Sebastes marinus L.). Examination of over 15 000 fish disclosed
that over three-fourths of all larval nematodes were Porrocaecuni ; the
remainder were other larval Anisakinae. Fishes such as halibut, pollock
29
Mann, 1954) reported disruption of growth as a result of tapeworm
infestation of Baltic Sea turbot, Rhonibus nicrximus (I,.). Fish in their
second year of life v rrc most seriously parasitized and complete
recovery of normal growth rate took several years.
Adult cestodes may occur in significant numbers in the digestive
tract of fishes, although their prevalence in marine teleosts is low in
comparison with that of other helminths. Linton (1941) described
many representatives from the western North Atlantic, and Wardle
(1932, 1935) surveyed the Pacific coast fauna. The Pseudophyllidean
genus Eubothrizcm Bloch (Abothrium Luhe) is common in marine and
fresh-water fishes. Several species occur in the digestive tracts of cod,
haddock, herring and other sea fishes (Nybelin, 1922 ; Sprehn, 1934).
Many other representatives of the Pseudophyllidea occur in teleost
fishes (Wardle and McLeod, 1952), while the order Tetraphyllidea is
well represented among the elasmobranchs (Woodland, 1927; Baer,
1948; Williams, 1968).
3. Nematodes
The nematode parasites of marine fishes have received attention
primarily because certain larvae that infest the flesh and viscera
reduce the commercial value of the host. An outstanding example is
the codworm, PorrocaecunL decipiens (Krabbe). The definitive host is
the harbor seal, Phocn vitulina L., according to Scott (1953), and
larvae occur in the flesh of cod, smelt, plaice, ocean pout and other
species of inshore marine fish (Heller, 1949; Scott, 1950, 1954, 1955).
Larvae may also pass from fish t o fish if infected smaller individuals
(for example smelt) are eaten by cod. Olsen and Merriman (1946)
reported ocean pout from New Brunswick t o be heavily infested-to
the extent that the flesh of some fish had a porous appearance. A
similar parasitization of ocean pout had been described from the same
area 25 years previously (Clemens and Clemens, 1921). Scott and
Martin (1957, 1959) found high prevalence but geographic variations
in infestation of cod from the Canadian Atlantic coast ; infestation
decreased in deeper waters and increased with age of the host. A
survey of Porroeaecum adults in seals (Scott and Fisher, 1958) did not
disclosed a direct distribution relationship with larvae in cod.
Templeman et al. (1057), in an extensive survey of groundfish in
the Newfoundland fishing area, found larval Porrocaecunh in cod, smelt,
plaice, witch flounder (Glyptocephalus cynoglossus (L.) ), haddock and
redfish (Sebastes marinus L.). Examination of over 15 000 fish disclosed
that over three-fourths of all larval nematodes were Porrocaecuni ; the
remainder were other larval Anisakinae. Fishes such as halibut, pollock