Production model based estimates of lower confidence limits for the abundance of West Greenland minke whales
The methodology advanced by Brandão and Butterworth (2007) for simulating catch sex sampling data in the process of computing lower confidence bounds for the abundance of the West Greenland minke whale population is applied to the new modelling scenarios developed at the March 2008 IWC Workshop on G...
| Main Authors: | , |
|---|---|
| Format: | Report |
| Language: | English |
| Published: |
International Whaling Commission
2008
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/11427/17832 https://open.uct.ac.za/bitstream/11427/17832/1/Brand%c3%a3o_Production_model_based_2008.pdf |
| Summary: | The methodology advanced by Brandão and Butterworth (2007) for simulating catch sex sampling data in the process of computing lower confidence bounds for the abundance of the West Greenland minke whale population is applied to the new modelling scenarios developed at the March 2008 IWC Workshop on Greenlandic Fisheries. To date calculations have extended only to MSYR = 2%, and been implemented for Models 3, 4b and 5 for a production model of resource dynamics, and to Model 4b for the age-structured population model of Witting and Schweder (2008). For Model 5 for the SW stratum treated as an independent stock, the MLE of pre-exploitation abundance K is finite, so that standard likelihood profile estimates of lower confidence bounds for abundance are provided. For the production model, lower bounds for Model 4b (the “influx” model) are higher than for Model 3 (the “redistribution” model); however these Model 4b bounds decrease when an age-structured population model is used instead of a production model. A concern, however, is indications of non-convergence of some of the model fits required to compute the deviance distributions which are used to determine the confidence bounds; this matter is being investigated further. |
|---|