Patterns of Spatial and Temporal Distribution of Humpback Whales at the Southern Limit of the Southeast Pacific Breeding Area

Abstract

Understanding the patterns of spatial and temporal distribution in threshold habitats of highly migratory and endangered species is important for understanding their habitat requirements and recovery trends. Herein, we present new data about the distribution of humpback whales (Megaptera novaeangliae) in neritic waters off the northern coast of Peru: an area that constitutes a transitional path from cold, upwelling waters to warm equatorial waters where the breeding habitat is located. Data was collected during four consecutive austral winter/spring seasons from 2010 to 2013, using whale-watching boats as platforms for research. A total of 1048 whales distributed between 487 groups were sighted. The spatial distribution of humpbacks resembled the characteristic segregation of whale groups according to their size/age class and social context in breeding habitats; mother and calf pairs were present in very shallow waters close to the coast, while dyads, trios or more whales were widely distributed from shallow to moderate depths over the continental shelf break. Sea surface temperatures (range: 18.2–25.9°C) in coastal waters were slightly colder than those closer to the oceanic realm, likely due to the influence of cold upwelled waters from the Humboldt Current system. Our results provide new evidence of the southward extension of the breeding region of humpback whales in the Southeast Pacific. Integrating this information with the knowledge from the rest of the breeding region and foraging grounds would enhance our current understanding of population dynamics and recovery trends of this species.

Movements and Timing of Humpback Whales (Megaptera novaeangliae) Within the Breeding Region of the Eastern South Pacific

“…This change to a coastal distribution is more evident in females with calves (Félix & Botero-Acosta, 2011;Guidino et al, 2014), a behavior that is maintained by migrating females after leaving the breeding area (Félix & Guzmán, 2014). Recently generated information on movements of whales that were satellite-tagged in Panama and Ecuador supports stratification in this population at breeding grounds (Guzmán & Félix, 2017) as well as the low number of matches in a large sample as in our study.…”

“…Eastern South Pacific humpback whales (Megaptera novaeangliae) (Breeding Stock G, according to the International Whaling Commission [IWC], 1998) migrate from feeding grounds located mainly in the surroundings of the Antarctic Peninsula (Dalla and to a lesser extent in the Magellan Strait (Gibbons et al, 2003;Acevedo et al, 2006Acevedo et al, , 2013 and Golfo de Corcovado in southern Chile (HuckeGaete et al, 2013) to their breeding region off northern Peru, Ecuador, Colombia, Panama, and Costa Rica (Flórez-González, 1991;Flórez-González et al, 1998;Félix & Haase, 2001;Rasmussen et al, 2007;Pacheco et al, 2009;Guidino et al, 2014;Guzmán et al, 2015). The connectivity between some feeding and breeding grounds has been demonstrated through photoidentification (Stone et al, 1990;Stevick et al, 2004;Acevedo et al, 2007;Rasmussen et al, 2007;Capella et al, 2008) and to a lesser extent with genetics (Caballero et al, 2001;Félix et al, 2012).…”

“…Whale abundance peaks off Panama in August and September (Guzmán et al, 2015) and off Colombia in August (Flórez-González et al, 1998); while off Ecuador, it is reported in July (Scheidat et al, 2000;Félix & Haase, 2001). In northern Peru, the peak is observed towards the end of the breeding season in September and October (Pacheco et al, 2009;Santillán, 2011;Guidino et al, 2014). This variability in abundance suggests that whales have an offshore path arriving first to Ecuador in July, then moving up north to Colombia, and finally moving further north to Panama.…”

“…Recently generated information on movements of whales that were satellite-tagged in Panama and Ecuador supports stratification in this population at breeding grounds (Guzmán & Félix, 2017) as well as the low number of matches in a large sample as in our study. We are aware that migration is a complex process with different timing and overlapping stages (Dawbin, 1966;Craig et al, 2003), and spatial segregation according to the whale's age/class (Félix & Haase, 2005;Félix & Botero-Acosta, 2011;Rasmussen et al, 2012;Guidino et al, 2014), which increases uncertainty and precludes reaching definitive conclusions from the available data. In the same line, we suggest caution with between-years matching results.…”

Presence of fin whales (Balaenoptera physalus) in Mejillones Bay, a major seaport area in northern Chile

“…Accordingly, we recorded 2 mother-calf pairs on 16 October 2006 but none stayed there (Table 1). However, fin whales are not known to regularly approach nearshore areas for calving in contrast to 2 other baleen whale species off western South America, i.e., humpback whale Megaptera novaeangliae (Guidino et al 2014) and southern right whale Eubalaena australis (Aguayo-Lobo et al 2008). The topographic characteristics of the coast provide possible further explanations (Clarke 1962).…”