32
K-H. Kock and 1. Everson
Trematomus species were estimated to become 15-21 years ([1] for
review) or even 20-30 years old, such as P. antarcticum [26]. Some of the
channichthyids from lesser-Antarctic/subAntarctic waters, such as C.
gunnari or C. aceratus attain ages of 12-15 years [1]. Ages of 10 years in
samples of the high-Antarctic channichthyid Chionodraco hamatus from
the Ross Sea [27] suggest that they attain similar ages as C. gunnari and
C. aceratus.
Ages of 18-22 years have been estimated for larger-sized (50-90 cm) N
rossii, G. gibberifrons and Lepidonotothen. squamifrons in the vicinity of
South Georgia and lIes Kerguelen ([ 1] for review). Ages of more than 30
years have been determined in A. mitopteryx and D. mawsoni from highAntarctic waters and are also very likely for the subAntarctic Dissostichus
eleginoides [1].
Growth
The growth model most commonly applied to Antarctic notothenioid fish
has been the von Bertalanffy growth formula [28]. Growth performance of
Antarctic fish has been commonly compared by comparing the parameters
K and Lex) of the von Bertalanffy growth formula. The parameter K is a
measure of how fast fish attain their final size. It is usually negatively
correlated with size (Loo, Woo) and hence is not very suitable for
comparing the growth performance of fish of different siz;es. This is much
better achieved by the index of growth performance P (= log K + log Woo)
which describes the growth rate at the point of inflexion of the size (mass)
growth curve [29].
We have used P to compare growth performance among notothenioids
and with ecologically similar fish species from boreal and temperate
waters (Fig. 1). Populations of some species, such as L. squamifrons
(points 3A-D), H antarcticus (lOA-C), C. gunnari (points llA,B) or T.
bernacchii (points 23A-D) exhibit considerable differences in their growth
parameters K and Woo; however their indices of growth performance are
very similar. The differences in growth parameters may reflect different
environmental conditions in which the individual population lives.
However, subjectivity in the age estimates could have also substantially
contributed to the differences in estimates of growth parameters [1].
Despite these reservations, some trends are apparent from Fig. 1.
Growth performance of notothenioids in lesser-Antarctic/subAntarctic
waters appears to be higher than in waters in the vicinity of the Antarctic
continent. Most species exhibit P values of 2-3. Two of them, N rossii
(points lA-C) and D. eleginoides (point 4), even have P values of 3-4.
Exceptions are L. nudifrons (point 8), L. larseni (point 9) and H
antarcticus (points 10A-C) which have comparatively high K values
K-H. Kock and 1. Everson
Trematomus species were estimated to become 15-21 years ([1] for
review) or even 20-30 years old, such as P. antarcticum [26]. Some of the
channichthyids from lesser-Antarctic/subAntarctic waters, such as C.
gunnari or C. aceratus attain ages of 12-15 years [1]. Ages of 10 years in
samples of the high-Antarctic channichthyid Chionodraco hamatus from
the Ross Sea [27] suggest that they attain similar ages as C. gunnari and
C. aceratus.
Ages of 18-22 years have been estimated for larger-sized (50-90 cm) N
rossii, G. gibberifrons and Lepidonotothen. squamifrons in the vicinity of
South Georgia and lIes Kerguelen ([ 1] for review). Ages of more than 30
years have been determined in A. mitopteryx and D. mawsoni from highAntarctic waters and are also very likely for the subAntarctic Dissostichus
eleginoides [1].
Growth
The growth model most commonly applied to Antarctic notothenioid fish
has been the von Bertalanffy growth formula [28]. Growth performance of
Antarctic fish has been commonly compared by comparing the parameters
K and Lex) of the von Bertalanffy growth formula. The parameter K is a
measure of how fast fish attain their final size. It is usually negatively
correlated with size (Loo, Woo) and hence is not very suitable for
comparing the growth performance of fish of different siz;es. This is much
better achieved by the index of growth performance P (= log K + log Woo)
which describes the growth rate at the point of inflexion of the size (mass)
growth curve [29].
We have used P to compare growth performance among notothenioids
and with ecologically similar fish species from boreal and temperate
waters (Fig. 1). Populations of some species, such as L. squamifrons
(points 3A-D), H antarcticus (lOA-C), C. gunnari (points llA,B) or T.
bernacchii (points 23A-D) exhibit considerable differences in their growth
parameters K and Woo; however their indices of growth performance are
very similar. The differences in growth parameters may reflect different
environmental conditions in which the individual population lives.
However, subjectivity in the age estimates could have also substantially
contributed to the differences in estimates of growth parameters [1].
Despite these reservations, some trends are apparent from Fig. 1.
Growth performance of notothenioids in lesser-Antarctic/subAntarctic
waters appears to be higher than in waters in the vicinity of the Antarctic
continent. Most species exhibit P values of 2-3. Two of them, N rossii
(points lA-C) and D. eleginoides (point 4), even have P values of 3-4.
Exceptions are L. nudifrons (point 8), L. larseni (point 9) and H
antarcticus (points 10A-C) which have comparatively high K values