Mc. Fabrizio et al., Modeling data from double-tagging experiments to estimate heterogeneous rates of tag shedding in lake trout (Salvelinus namaycush), CAN J FISH, 56(8), 1999, pp. 1409-1419
Citations number
35
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
Data from mark-recapture studies are used to estimate population rates such
as exploitation, survival, and growth. Many of these applications assume n
egligible tag loss, so tag shedding can be a significant problem. Various t
ag shedding models have been developed for use with data from double-taggin
g experiments, including models to estimate constant instantaneous rates, t
ime-dependent rates, and type I and II shedding rates. In this study, we us
ed conditional (on recaptures) multinomial models implemented using the pro
gram SURVIV (G.C. White. 1983. J. Wildl. Manage. 47: 716-728) to estimate t
ag shedding rates of lake trout (Salvelinus namaycush) and explore various
potential sources of variation in these rates. We applied the models to dat
a from several long-term double-tagging experiments with Lake Superior lake
trout and estimated shedding rates for anchor tags in hatchery-reared and
wild fish and for various tag types applied in these experiments. Estimates
of annual tag retention rates for lake trout were fairly high (80-90%), bu
t we found evidence (among wild fish only) that retention rates may be sign
ificantly lower in the first year due to type I losses. Annual retention ra
tes for some tag types varied between male and female fish, but there was n
o consistent pattern across years. Our estimates of annual tag retention ra
tes will be used in future studies of survival rates for these fish.