ANTARCTIC BENTHOS
133
one of the Chaenichthyid fishes, Pagetopsis macropterus, at McMurdo
Sound. A specimen was captured by hand as it rested on a sponge.
Whenever disturbed it swam slowly close to the bottom, and when left
it came to rest on a sponge again. It was suggested that this may be
its usual feeding position, raised somewhat in the water column, waiting
for prey to swim past. Stomach contents of small fish and Crustacea in
Pagetopsis seems additional evidence for this.
These authors described a defence posture with dorsal fin erected,
pectoral fins opened widely at right angles to the body, and the body
bent. A wide range of oxygen consumption was recorded in this fish,
and Robilliard and Dayton noted that the respiratory rates reported
by various authors were somewhat discrepant.
6. Reproduction
Marshall (196413) discussed what was known of reproduction in
Antarctic fishes, especially in the Scotia Arc and the Antarctic Peninsula.
Some evidence pointed to some Antarctic fishes spawning during the
late spring and early summer. Eggs of Harpagifer bispinis (Schneider)
have been collected in November, and recently hatched specimens of
Artedraco and Gymnodraco acuticeps Boulenger in December and
January. However, newly hatched larvae of Pagetopsis macropterm
have been taken in May and June, and young larvae of Chionodraco
kathleenae Regan in October. In South Georgia the main spawning
period appears to be in autumn, based upon the following observations :
Paraliparis gracilis Norman (eggs in April), Champsocephalus gunnari
Lonnberg (spawn in April, May), Chaenocephalus aceratus Lonnberg
(spawn from late March to April) and Notothenia rossii Richardson
(spawn in April and May).
Marshall (196413, p. 215) believed that on all the evidence available
to him most Antarctic species lay their eggs on the sea floor. He had
previously (1953) shown that in comparison with temperate and tropical
fishes with a similar habit of producing demersal eggs, the eggs of
Antarctic fishes were larger and more yolky. Correlated with this was
the observation that the larval fishes hatching from these eggs were
larger and more advanced.
The data available to Andriashev (1965) was in general agreement
with Marshall’s conclusions. Larvae of Antarctic fishes are comparatively large, and many have a long pelagic stage. In many species, the
larvae, though pelagic, occur in midwater rather than close to the
surface. As a result of an analysis of midwater fishes in the Ross Sea,
DeWitt (1970) was able to show that even the juveniles of the dominant
A.x.B.-~O
6
133
one of the Chaenichthyid fishes, Pagetopsis macropterus, at McMurdo
Sound. A specimen was captured by hand as it rested on a sponge.
Whenever disturbed it swam slowly close to the bottom, and when left
it came to rest on a sponge again. It was suggested that this may be
its usual feeding position, raised somewhat in the water column, waiting
for prey to swim past. Stomach contents of small fish and Crustacea in
Pagetopsis seems additional evidence for this.
These authors described a defence posture with dorsal fin erected,
pectoral fins opened widely at right angles to the body, and the body
bent. A wide range of oxygen consumption was recorded in this fish,
and Robilliard and Dayton noted that the respiratory rates reported
by various authors were somewhat discrepant.
6. Reproduction
Marshall (196413) discussed what was known of reproduction in
Antarctic fishes, especially in the Scotia Arc and the Antarctic Peninsula.
Some evidence pointed to some Antarctic fishes spawning during the
late spring and early summer. Eggs of Harpagifer bispinis (Schneider)
have been collected in November, and recently hatched specimens of
Artedraco and Gymnodraco acuticeps Boulenger in December and
January. However, newly hatched larvae of Pagetopsis macropterm
have been taken in May and June, and young larvae of Chionodraco
kathleenae Regan in October. In South Georgia the main spawning
period appears to be in autumn, based upon the following observations :
Paraliparis gracilis Norman (eggs in April), Champsocephalus gunnari
Lonnberg (spawn in April, May), Chaenocephalus aceratus Lonnberg
(spawn from late March to April) and Notothenia rossii Richardson
(spawn in April and May).
Marshall (196413, p. 215) believed that on all the evidence available
to him most Antarctic species lay their eggs on the sea floor. He had
previously (1953) shown that in comparison with temperate and tropical
fishes with a similar habit of producing demersal eggs, the eggs of
Antarctic fishes were larger and more yolky. Correlated with this was
the observation that the larval fishes hatching from these eggs were
larger and more advanced.
The data available to Andriashev (1965) was in general agreement
with Marshall’s conclusions. Larvae of Antarctic fishes are comparatively large, and many have a long pelagic stage. In many species, the
larvae, though pelagic, occur in midwater rather than close to the
surface. As a result of an analysis of midwater fishes in the Ross Sea,
DeWitt (1970) was able to show that even the juveniles of the dominant
A.x.B.-~O
6