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Exploring the assumptions of multi-stock assessment models for humpback whales (Megaptera novaeangliae) in the Southern Hemisphere: using Breeding Stocks D and E as an example

Citation

Leaper, R and Peel, S and Peel, D and Gales, N, Exploring the assumptions of multi-stock assessment models for humpback whales (Megaptera novaeangliae) in the Southern Hemisphere: using Breeding Stocks D and E as an example, The Journal of Cetacean Research and Management, 2011, (Special Issue 3) pp. 119-128. ISSN 1561-0713 (2011) [Refereed Article]


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Copyright Statement

Copyright 2011 The International Whaling Commission

Official URL: http://www.iwcoffice.org/JCRM.htm

Abstract

There is potential value in exploring multi-stock models to address situations where humpback stocks are mixing. However, sensitivity to the assumptions underlying these models has yet to be fully explored. Using a simple simulation approach, the assumptions of a population model that allows for mixing of humpback whale (Megaptera novaeangliae) stocks D and E on feeding areas has been explored by relaxing the assumptions of the original Johnston and Butterworth model in a number of plausible ways. First the ability of the model to estimate parameters was checked for a situation where simulated data are generated from an underlying model of exactly the same form for which the actual values of these parameters are known (Scenario 1). Then the ability of the model to estimate these parameters when alternative forms and assumptions were used for the underlying model generating the data was investigated. Specifically, stocks were allowed to mix non-uniformly across each feeding area and catch was non-uniformly distributed across each feeding area (Scenario 2). The consequences of density dependence implemented on feeding rather than breeding areas (Scenario 3) were also examined. The original mixing model was robust to alternate mixing and catch allocation scenarios in all but one of the simulations, but when density dependence acted at the level of the feeding rather than the breeding areas, the model produced estimates that were quite different from the underlying population. It is recommend that the inclusion of density dependence on feeding areas in models that allow for mixing of whales on these grounds be investigated further

Item Details

Item Type:Refereed Article
Keywords:HUMPBACK WHALE; ASSESSMENT; MIXING; CATCH ALLOCATION; DENSITY DEPENDENCE; SIMULATION;
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Coastal and Estuarine Flora, Fauna and Biodiversity
Author:Leaper, R (Dr Rebecca Leaper)
ID Code:75512
Year Published:2011
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2012-02-01
Last Modified:2012-08-20
Downloads:1 View Download Statistics

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