38
CARL J. SINDERMANN
of fishes and Dawson (1964) has compiled a bibliography of fish
anomalies which contains over a thousand references. Structural
abnormalities in several skate species have been described recently by
Templeman (1965). Included were such conditions as : separation of
pectoral fins from the head, which has been observed repeatedly in
the past in other parts of the North Atlantic ; curvature of the vertebral
column, a condition found in many teleosts also ; and " blunt snout ",
caused by skeletal defects. Letaconnoux (19491, who reported on
teratological studies of marine fishes landed in Prance, also noted
malformations of the pectoral fins in skates, and described an interesting
condition of pigmentation of the normally unpigmented blind side of
plaice, often associated with incomplete eye migration. Letaconnoux
also observed a common abnormality of " short tail "-a
definite
abbreviation of the caudal region seen in many species of fishes, due
to twisting, compression or fusion of vertebrae. A similar shortening,
torsion and diminution of the caudal region has been observed frequently in immature Atlantic herring from the Gulf of Maine, especially
in samples taken by bottom trawls rather than conventional surface
gear (Sindermann, unpublished). Individuals of other species, such as
haddock, have also been found with spinal abnormalities in the western
North Atlantic. Although this condition may be due to a bone disease,
it seems more likely that these and other structural abnormalities can
be attributed to defective embryonic development.
" Eugheadedness " (Mopskopfe), a shortening of the snout, was
noted by Letaconnoux (op. cit.) in several teleosts, particularly the
gadoids. This condition has been reported by a number of other
authors. Gudger (1930) and Raiiey (1952) described it in striped bass
(Fig. 1 l ) , and Maim (1954) reported on the occurrence of " pugheads "
among Baltic Sea pike, thought to be genetic, but possibly influenced
by environmental factors such as lack of oxygen or salinity variations
during embryonic life. No difference in weight was seen in such fish
as compared with normal fish, but they are so often rejected by the
European shopper that they are usually culled in advance. A pugheaded herring was described by Ford (1930), who also cited earlier
evidence for the hereditary origin of the abnormality in fishes.
Abnormal conditions in larval fishes, some undoubtedly genetic
and some due to environmental variations, are most often seen in
hatcheries, but structural defects are sometimes seen in larvae and
post-larvae taken in plankton collections. Experimental variation of
such single factors as temperature at time of hatching can drastically
modify or inhibit formation of the jaws of larvae and can cause an
increase in occurrence of other gross abnormalities. Volodin (1960),
CARL J. SINDERMANN
of fishes and Dawson (1964) has compiled a bibliography of fish
anomalies which contains over a thousand references. Structural
abnormalities in several skate species have been described recently by
Templeman (1965). Included were such conditions as : separation of
pectoral fins from the head, which has been observed repeatedly in
the past in other parts of the North Atlantic ; curvature of the vertebral
column, a condition found in many teleosts also ; and " blunt snout ",
caused by skeletal defects. Letaconnoux (19491, who reported on
teratological studies of marine fishes landed in Prance, also noted
malformations of the pectoral fins in skates, and described an interesting
condition of pigmentation of the normally unpigmented blind side of
plaice, often associated with incomplete eye migration. Letaconnoux
also observed a common abnormality of " short tail "-a
definite
abbreviation of the caudal region seen in many species of fishes, due
to twisting, compression or fusion of vertebrae. A similar shortening,
torsion and diminution of the caudal region has been observed frequently in immature Atlantic herring from the Gulf of Maine, especially
in samples taken by bottom trawls rather than conventional surface
gear (Sindermann, unpublished). Individuals of other species, such as
haddock, have also been found with spinal abnormalities in the western
North Atlantic. Although this condition may be due to a bone disease,
it seems more likely that these and other structural abnormalities can
be attributed to defective embryonic development.
" Eugheadedness " (Mopskopfe), a shortening of the snout, was
noted by Letaconnoux (op. cit.) in several teleosts, particularly the
gadoids. This condition has been reported by a number of other
authors. Gudger (1930) and Raiiey (1952) described it in striped bass
(Fig. 1 l ) , and Maim (1954) reported on the occurrence of " pugheads "
among Baltic Sea pike, thought to be genetic, but possibly influenced
by environmental factors such as lack of oxygen or salinity variations
during embryonic life. No difference in weight was seen in such fish
as compared with normal fish, but they are so often rejected by the
European shopper that they are usually culled in advance. A pugheaded herring was described by Ford (1930), who also cited earlier
evidence for the hereditary origin of the abnormality in fishes.
Abnormal conditions in larval fishes, some undoubtedly genetic
and some due to environmental variations, are most often seen in
hatcheries, but structural defects are sometimes seen in larvae and
post-larvae taken in plankton collections. Experimental variation of
such single factors as temperature at time of hatching can drastically
modify or inhibit formation of the jaws of larvae and can cause an
increase in occurrence of other gross abnormalities. Volodin (1960),