30
K.-H. Kock and 1. Everson
In what follows, we review information on age and growth, reproduction
and seasonality in feeding and then consider the results in the light of the
hypothesis that Antarctic notothenioid fish grow slowly.
Age and Growth Studies in Antarctic Fish
There are more than 120 publications which contain information on age
and growth of Antarctic notothenioid fish. The majority of these were
published after 1975 when commercial fishing provided a ready supply of
material on a variety of species. Up to that date, there were only 10 papers
published on species such as Notothenia coriiceps, N rossii or
Trematomus bernacchii [i.e. 10-13].
Age and growth estimates are limited to a number of nototheniids, a few
channichthyids, and Harpagifer antarcticus. They are still lacking for
members of the other notothenioid families Artedidraconidae and
Bathydraconidae. Most age estimates originate from lesser-Antarctic/subAntarctic species. Published information on age and growth of highAntarctic fish is limited to a few species of the nototheniid genus
Trematomus,
Aethotaxis
mitopteryx,
Dissostichus
mawsoni,
Pleuragramma antarcticum, and Chionodraco hamatus.
Age Determination
Otoliths, scales, fin rays and vertebrae and other skeletal bones have all
been shown to exhibit rhythmic patterns that can be related to changes in
daily, seasonal or annual growth [1,14,15]. The growth patterns present on
these hard structures have been used to estimate age.
Otoliths should be the most suitable structures for ageing as they contain
a complete record of growth from hatching to capture [16]. They are not
subject to resorption in times of calcium shortage. Furthermore, they can
be used to estimate age in fish species which lack scales, such as
channichthyids. Ageing using otoliths has been mostly conducted on
sectioned otoliths both on seasonal growth increments and on microstructural growth increments exhibiting daily increments ([8,15] for
review).
Scales do not contain the whole growth history of a fish. In nototheniids,
they do not form earlier than several months after hatching. Replacement
scales are common. The margins of the scales become eroded with age,
and annuli may be obscured by the compression or erosion of sc1erites in
the marginal zone in older fish. Resorption processes may lead to
additional checks which may be misinterpreted as representing annuli
(,false check'). Scale circuli analysis should thus ideally combine the
determination of the onset of scale formation and validation with data
K.-H. Kock and 1. Everson
In what follows, we review information on age and growth, reproduction
and seasonality in feeding and then consider the results in the light of the
hypothesis that Antarctic notothenioid fish grow slowly.
Age and Growth Studies in Antarctic Fish
There are more than 120 publications which contain information on age
and growth of Antarctic notothenioid fish. The majority of these were
published after 1975 when commercial fishing provided a ready supply of
material on a variety of species. Up to that date, there were only 10 papers
published on species such as Notothenia coriiceps, N rossii or
Trematomus bernacchii [i.e. 10-13].
Age and growth estimates are limited to a number of nototheniids, a few
channichthyids, and Harpagifer antarcticus. They are still lacking for
members of the other notothenioid families Artedidraconidae and
Bathydraconidae. Most age estimates originate from lesser-Antarctic/subAntarctic species. Published information on age and growth of highAntarctic fish is limited to a few species of the nototheniid genus
Trematomus,
Aethotaxis
mitopteryx,
Dissostichus
mawsoni,
Pleuragramma antarcticum, and Chionodraco hamatus.
Age Determination
Otoliths, scales, fin rays and vertebrae and other skeletal bones have all
been shown to exhibit rhythmic patterns that can be related to changes in
daily, seasonal or annual growth [1,14,15]. The growth patterns present on
these hard structures have been used to estimate age.
Otoliths should be the most suitable structures for ageing as they contain
a complete record of growth from hatching to capture [16]. They are not
subject to resorption in times of calcium shortage. Furthermore, they can
be used to estimate age in fish species which lack scales, such as
channichthyids. Ageing using otoliths has been mostly conducted on
sectioned otoliths both on seasonal growth increments and on microstructural growth increments exhibiting daily increments ([8,15] for
review).
Scales do not contain the whole growth history of a fish. In nototheniids,
they do not form earlier than several months after hatching. Replacement
scales are common. The margins of the scales become eroded with age,
and annuli may be obscured by the compression or erosion of sc1erites in
the marginal zone in older fish. Resorption processes may lead to
additional checks which may be misinterpreted as representing annuli
(,false check'). Scale circuli analysis should thus ideally combine the
determination of the onset of scale formation and validation with data