Improved Arctic Charr
farming through strain selection
Comparison of Austrian strains from the wild
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, Aquaflow ref. :
TL2003-1725
Commercial aquaculture of Arctic charr, Salvelinus
alpinus, is a relatively new and growing area of finfish culture in
Austria, as well as in Europe. At present, only a handful of Austrian
farmers produce charr for the table and fish are sold locally. However, this
species is very promising, commercially (market prices and demand are
relatively high) as well as biologically (low temperatures for growth and
high stocking densities are possible). In the wild, variation in pheno-type
between populations of Arctic charr is well-known and widely reported in the
literature.
One of the principal goals of the project, was to
take the opportunity to capitalise on natural phenotypic variation, to
increase the numbers of strains available to the Austrian farming industry
and to screen these new strains for characteristics that may be valuable for
the charr aquaculture industry.
Eggs and milt of ripe wild Arctic charr, from 7
strains (Lunzer Ober-, Mitter- und Untersee; Erlaufsee; Grundlsee,
Fuschlsee; Stappniksee), were collected and fertilised successfully and
compared in respect to ova characteristics (size and relative fecundity),
embryonic development and mortality. Further comparisons during the larvae
and fry stage under similar conditions have been focused on growth and
mortality.
In general, charr strains from Austria (as well as
from other parts of the Alps) seem to be more homogenous than investigated
strains in the northern parts of Europe, also in respect to parameters of
commercial farming interests. The study contains also general information
for improved farming of Arctic charr:
Differences in spawning seasons of experimental
strains indicate the importance of temperature as a trigger of the timing in
spawning. Cold temperature
during the summer in lakes Stapniksee and Mittersee seems to be decisively
for advanced spawning. When eggs are collected from the wild, like in the
majority of Austrian hatcheries, early spawning strains may come up to a
“good” size before the slow growth period of the long and cold winter
season.
There is a high variability in egg size of Alpine
strains. In many investigations size at hatching has been reported to be
positively correlated with egg size; larger fish at hatching are very likely
to have some advantages in survival and fitness, at least during initial
feeding period.
Strains with small sized, native broodstock or low
native growth are not necessarily strains with low growth potential and
therefore low commercial interest.
In the present study, as is commonly observed in the
farming of salmonids, high mortality during the initial feeding stage has
been observed: Four strains reared under the same conditions for 504 days
exhibit more than 97% of total mortality within the first 100 days. However,
the course of mortality during initial feeding stage seemed to be more size
dependent than age dependent. The end of this “sensitive” period in all
strains was when fish reached a size of about 1g.
Therefore strategies should be adopted to accelerate the growth, to
pass the sensitive size within a very short time.
For
more information, contact:
Helmut Kummer
Department of Hydrobiology
Fisheries and Aquaculture
University of Agricultural Sciences
Vienna - Austria
Tel.: 0043 1 47654 5213
Fax: 0043 1 47654 5217
E-mail:
helmut@edv1.boku.ac.at