| Abstract: | In 1980 and 1981, more than 68,000 juvenile halibut were tagged in the Gulf of Alaska and Southeast Alaska in an effort to obtain estimates of movements of juvenile halibut. In this paper we develop a maximum likelihood method for estimating the movement between International Pacific Halibut Commission (IPHC) regulatory Areas 3B, 3A, 2C, 2B and 2A. In addition to the movement rates, we also estimate the sizespecific natural mortality, tagging mortality and size selectivity for commercial gear in Areas 3B and 3A. We found that all of these parameters could be estimated with low confounding, and that the predicted recovery pattern of tags conforms closely to the observed recoveries. The best fitting model estimates that there are substantial southerly movements of juvenile halibut; for example, we estimate that 17% of fish tagged in 3B would recruit as adults to 2B, and that 25% of fish tagged in 3A would recruit as adults to 2B. Further improvements in the analysis could include smaller spatial scale of analysis, and combining tagging analysis with catch-at-age data. |
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