Mc. Fabrizio et al., Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush), CAN J FISH, 58(2), 2001, pp. 262-272
Citations number
40
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
In 1976, the Wisconsin Department of Natural Resources established a refuge
for a nearly depleted population of lake trout (Salvelinus namaycush) at G
ull Island Shoal, Lake Superior. The refuge was intended to reduce fishing
mortality by protecting adult lake trout. We examined the growth dynamics o
f these lake trout during the period of recovery by comparing estimates of
individual growth before and after the refuge was established. Our estimate
s are based on an annual mark-recapture survey conducted at the spawning ar
ea since 1969. We developed a model that allowed mean growth rates to diffe
r among individuals of different sizes and that accommodated variation in g
rowth rates of individuals of the same size. Likelihood ratio tests were us
ed to determine if the mean growth increments of lake trout changed after t
he refuge was established. Our results suggest that growth of mature lake t
rout (particularly wild fish) decreased significantly in the postrefuge per
iod. This decreased growth may have been associated with a reduction in foo
d availability. We also observed reductions in growth as wild fish grew old
er and larger, which suggests that the growth of these fish may be adequate
ly approximated by a von Bertalanffy growth model if it becomes possible to
obtain accurate ages.