| dc.description.abstract | The development of Cystidicola cristivomeri in lake
trout, Salvelinus namaycush, and C, farionis in rainbow trout,
Salmo gairdneri, is described. The population biology of
C. cristivomeri was investigated in lake trout in three lakes
in northwestern Ontario and in arctic char, S. alpinus,
Gaviafaeces Lake, Northwest Territories.
Young lake trout fed selectively on large Mysis
relicta which were more frequently infected with C. cristivomeri
(up to 5.1%) than small mysids. Pontoiporeia affinis was not
a suitable intermediate host in nature and there was no
evidence that fish paratenic hosts were important in transmitting
this nematode to lake trout.
Third-stage larvae given to lake trout migrated
directly via the pneumatic duct to the swimbladder. In
experimentally infected fishes, at 4-10°C, C. cristivomeri were
mature after 67 (males) and 210 days (females); C. farionis were
mature after 112 (males) and 235 days (females). There was no
measurable mortality of C. cristivomeri after 600 days in
experimentally infected lake trout.
Field studies indicated that most C, cristivomeri
live at least 10 years and some probably live longer. The
development of female worms to sexual maturity was retarded
and they grew more slowly when large numbers of C, cristivomeri
were present in the swimbladder. Short female worms produced eggs at a slower rate than longer females. This density
dependent regulation of C, cristivomeri at the infrapopulation
level may result in long-term stability of
the nematode suprapopulation in a lake.
The number of ulcerative lesions on the inner
surface of the swimbladder of lake trout was directly
dependent upon the number of mature C. cristivomeri
present in a fish. | |
