30
CARL J. SINDERMANN
(Pollachius virens (L.) ) and sea raven (HPwLitriptPrus americmus
(Gmelin) ) living in the neighborhood of seal colonies were infested also.
Marketing problems with worm-infested fillets were felt to be more
serious with Porrocuecum, whose larvae are large and brown-colored,
than with other larval Anisakinae, which are small and white.
Studies of larval marine nematodes of the sub-family Anisakinae
by a number of authors (Kahl, 1938a; Baylis, 1914) lead to some confusion about identification of larval Porrocaecum, since small specimens
may lack the diagnostic intestinal caecum which separates this genus
from others. Feeding studies with seals (Scott, 1953, 1956) established
that most larval worms from cod, plaice, smelt and eelpout of the
western North Atlantic were actually P. decipiens. Other nematode
genera represented by larvae in food fishes of the North Atlantic include Eustoma and Anasakis. Templeman et al. (1957) have summarized
the problems inherent in specific identification of larval Heterocheilidae.
Porrocaecum larvae have been reported from 18 species of Pacific
fishes, including the Pacific cod, Gadus macrocephalus Tilesius, by
Yamaguti (1935). Smelt, cod, redfish and other species from the North
Sea were also found to harbor this nematode (Martin, 1921; Kahl,
1936, 1939). Grainger (1959) identified as Porrocaecum larval nematodes
from cod and other fishes from Greenland waters and the Barents Sea.
Infestation of cod livers by larval Contracaecum aduncum (Rud.),
also of the subfamily Anisakinae, has been responsible for considerable
economic losses in the Baltic Sea, according to Markowski (1937),
Shulman (1948, 1959), Petrushevskii and Shulman (1955) and Getsevichyute (1955). Numbers of worms per liver reached 100, and
parasitized fish suffered loss of total weight and liver mass (Fig. 9).
Larger, deeply penetrating worms were more harmful, and young
fish or spawning fish showed less tolerance to infestation. Liver fat
content and oil yield were seriously reduced by parasitization. Contracaecum was also found in cod from the White and Murman Seas,
but in lesser frequencies.
An interesting example of nematode parasitization that is of
serious consequence t o the host has been described by Janiszewska
(1939). Flounders of the eastern Atlantic are often heavily parasitized
by Cucullanellus minutus (Rud.). Larvae invade the intestinal wall,
causing extensive pathological changes. After overwintering, the
worms re-enter the lumen of the digestive tract and mature during
early summer.
A common larval nematode of the subfamily Acanthocheilinae is
Eustoma (Anacanthocheilus) rotundatum (Rud.), which occurs as a larva
in the mesenteries and viscera of many North Atlantic fishes, including
CARL J. SINDERMANN
(Pollachius virens (L.) ) and sea raven (HPwLitriptPrus americmus
(Gmelin) ) living in the neighborhood of seal colonies were infested also.
Marketing problems with worm-infested fillets were felt to be more
serious with Porrocuecum, whose larvae are large and brown-colored,
than with other larval Anisakinae, which are small and white.
Studies of larval marine nematodes of the sub-family Anisakinae
by a number of authors (Kahl, 1938a; Baylis, 1914) lead to some confusion about identification of larval Porrocaecum, since small specimens
may lack the diagnostic intestinal caecum which separates this genus
from others. Feeding studies with seals (Scott, 1953, 1956) established
that most larval worms from cod, plaice, smelt and eelpout of the
western North Atlantic were actually P. decipiens. Other nematode
genera represented by larvae in food fishes of the North Atlantic include Eustoma and Anasakis. Templeman et al. (1957) have summarized
the problems inherent in specific identification of larval Heterocheilidae.
Porrocaecum larvae have been reported from 18 species of Pacific
fishes, including the Pacific cod, Gadus macrocephalus Tilesius, by
Yamaguti (1935). Smelt, cod, redfish and other species from the North
Sea were also found to harbor this nematode (Martin, 1921; Kahl,
1936, 1939). Grainger (1959) identified as Porrocaecum larval nematodes
from cod and other fishes from Greenland waters and the Barents Sea.
Infestation of cod livers by larval Contracaecum aduncum (Rud.),
also of the subfamily Anisakinae, has been responsible for considerable
economic losses in the Baltic Sea, according to Markowski (1937),
Shulman (1948, 1959), Petrushevskii and Shulman (1955) and Getsevichyute (1955). Numbers of worms per liver reached 100, and
parasitized fish suffered loss of total weight and liver mass (Fig. 9).
Larger, deeply penetrating worms were more harmful, and young
fish or spawning fish showed less tolerance to infestation. Liver fat
content and oil yield were seriously reduced by parasitization. Contracaecum was also found in cod from the White and Murman Seas,
but in lesser frequencies.
An interesting example of nematode parasitization that is of
serious consequence t o the host has been described by Janiszewska
(1939). Flounders of the eastern Atlantic are often heavily parasitized
by Cucullanellus minutus (Rud.). Larvae invade the intestinal wall,
causing extensive pathological changes. After overwintering, the
worms re-enter the lumen of the digestive tract and mature during
early summer.
A common larval nematode of the subfamily Acanthocheilinae is
Eustoma (Anacanthocheilus) rotundatum (Rud.), which occurs as a larva
in the mesenteries and viscera of many North Atlantic fishes, including