Applying a multi-state open robust design model for estimating residence patterns of humpback whales in a breeding ground in the eastern pacific region.
Supervisors: Guido J. Parra, Lilián Flórez González (Flinders Univ)
The Southeast Pacific humpback whale population (Stock G) migrates annually from feeding grounds in Antarctica and the Patagonian Channels to breeding grounds in the North of Peru, Ecuador, Colombia, Panama and Costa Rica. Gorgona island National Park (GNP) located in the southwest of the Colombian Pacific, represents a key breeding ground for the southeast pacific humpback whale population. In this study I investigate the residence patterns of humpback whales that breed in the GNP by analysing photo-identification data collected over 13 breeding seasons (1986-1994, 1997-1999, 2003-2004). A sub-set of the data (nine breeding seasons from 1986-1994) was used to model residence patterns applying a multistate open robust design mark recapture model (MSORD). It was used MSORD to evaluate the effect of reproductive status and gender on residence patterns of three demographic groups of humpback whales: calving females, adult males, and unknown sex adults. Across the whole study period analyzed, the recapture rate within a breeding season was estimated in average of 17.95% for all groups. The best model suggested similar patterns across seasons but differences between demographic groups. It was observed staggered arrival and departure patterns and differences in residence patterns in all groups. Adult males spend more time than calving females followed by unknown sex adults. The results of this work indicate that GNP is important area for nursing, resting and mating.

MSORD model is a useful method to better understand movement patterns by reducing bias of sampling measurements. This work will provide a baseline to evaluate one aspect of the population dynamics of humpback whales in GNP, before and after an anthropic intervention and propose management measures to reduce its impact.

Key words: multi-state open robust design, mark-recapture, breeding ground, residence, Southern Pacific, humpback whale, Megaptera novaeangliae.