Abstract
Migrating humpback whales from northern and southern feeding grounds come to the tropical waters near Osa Peninsula, Pacific of Costa Rica, to reproduce and raise their calves. Planning effective marine protected areas that encompass humpback critical habitats require data about which oceanographic features influence distribution during the breeding period. This study examines the relationship between water depth and ocean floor slope with humpback whale distribution, based on sightings during two breeding seasons (2005 and 2006). Data are from the Southern and Northern subpopulations in the Eastern Tropical Pacific (ETP). Analysis followed the basic principles of the Ecological Niche Factors Analysis (ENFA), where indices of Marginality and Tolerance provide insights on the restrictiveness of habitat use. At a fine scale, physical factors such as water depth and slope define the critical breeding and nursing habitat for M. novaeangliae. Divergence in the subsamples means of depths and slope distribution, with the global mean of the study area in both eco-geographical variables, determine habitat requirements restricted by topographic features such as depths (< 100 m) and slope (< 10%), and locate the key breeding and nursing habitat of the species within the continental shelf domains. Proposed Marine Protected Areas (MPA's) network plans should consider connectivity of Cafio Island-Drake Bay and the extension of Corcovado National Park maritime borders.
Highlights
Humpback whales (Megaptera novaeangliae) aggregate in winter breeding and calving grounds along continental margins, coastal islands or archipelagos located in tropical waters
The feeding areas in the North Pacific Ocean include the coasts of Alaska and California, while breeding grounds encompass the Hawaiians islands and Mexican waters, as well as the Eastern Tropical Pacific coast of Central America
Wintering Humpback whales are found along the western coastline of the Eastern Tropical Pacific from May-November, with the greatest numbers occurring in July and August (Félix and Haase 2001)
Summary
Humpback whales (Megaptera novaeangliae) aggregate in winter breeding and calving grounds along continental margins, coastal islands or archipelagos located in tropical waters. Wintering Humpback whales are found along the western coastline of the Eastern Tropical Pacific from May-November, with the greatest numbers occurring in July and August (Félix and Haase 2001) To their northern counterpart, Southern Humpback whales that forage in the northernmost feeding area along the South American Coast migrate to the northernmost breeding grounds off Costa Rica. Both sub-populations of humpback whales, the Northern and the Southern Pacific groups, overlap in Costa Rica’s territorial waters, off the Osa Peninsula. Changes in movement and activity patterns during encounters with tourist boats have been reported in several sites including Ecuador (Corkeron 1995, Scheidat et al 2004, Félix and Haase 2005)
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