Stage-Structured Tag-Return and Capture-Recapture Models

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2001-04-16

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Abstract

Ecologists and conservation biologists have had an increasing interest in landscapeecology, fragmentation and meta-population structures and dynamics for endangered or threatened species of wildlife (Nichols et al. 1992).They have realized the need for parameter estimates to use in the multi-state models;and have tried estimation of transitionprobabilities among stages using tag-return and capture-recapture models. Thesetransition probabilities are composed of survival and movement rates andcan only be estimated separately when an additional assumption is made(Brownie et al. 1993) that movement occurs at the end of theinterval between time + 1.We generalize this workto allow different movement patterns in the intervalfor multiple tag-recovery and capture-recapture experiments. With methods of separating survival and movement rates in multi-state tag-return and capture-recapture models,we develop multi-state fishery tag return models with potential forfisheries that have multiple sites or patches with movement possible between sites. We build on models developed by Brownie et al. (1985), Pollock et al. (1991, 1995), Hoenig et al. (1998 a, b), and Hearn et al. (1998) on twice-a-year tagging for single state models.These methods allow the estimation of patch-specific natural and fishingmortality rates and movement rates between patches. We then develop multi-state fishery tag-return and capture-recapture models with potential forfisheries that have multiple sites or patches withmovement possible between sites when taggingtakes place twice a year.These methods allow the estimation of patch-specific reporting, natural and fishing mortality rates, and movement rates between patcheswith movement time following a uniform distribution for two special cases: (1) a two-site tag-return fisheries model;(2) a two-site model with capture-recapture catch and releasesampling in a marine reserve closed to regular fishing and the more usual tag-return sampling in the fishery area, since marine reserves which provide a refuge from fishing are gaining in popularity as a tool of fisheries management, but their effectiveness needs to beevaluated. We present small simulation studies andcompare the Relative Bias and Relative Standard Errors (RES) of estimatesas well as the correlations between estimates.

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Degree

PhD

Discipline

Biomathematics

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