A historical feeding ground for humpback whales in the eastern South Pacific revisited: the case of northern Patagonia, Chile

Abstract

1. Since 2000, an increasing number of humpback whale sightings have been recorded in northern Chilean Patagonia (mostly between 41.5 S and 44 S) from dedicated aerial and marine surveys and also opportunistic and land-based platforms during austral summer and autumn months.2. Based on local knowledge from the early years of coastal whaling suggesting the historic presence of humpback whales in the area, and more recent observations confirming feeding groups, mother-calf pairs, and philopatry, it is proposed that a proportion of the eastern South Pacific humpback whales consistently use the Chiloe-Corcovado region to feed and nurse their young.3. This mid-latitude area could be regarded as the northernmost feeding ground for humpback whales in South America, extending the previous known range some 1300 km north.4. These findings provide further evidence for alternative life-strategies other than traditional migration and highlight the importance of northern Patagonian fjords to resolve questions that are central for large baleen whale conservation and management such as the extent and characteristics of spatio-temporal habitat use and overlap with human activities.5. The need for future research on the migratory movements and population structure of this poorly understood population of humpback whales is emphasized, while an account is given of the threats they currently face.

Evidence of spatial structuring of eastern South Pacific humpback whale feeding grounds

“…These similarities in coloration patterns suggest that humpback whales in the ESP also form a 'structured stock', consisting of 3 geographically distinct 'feeding herds'. Despite the fact that the relatively low number of identified whales on CG could induce the lack of detection of some migratory movements to southernmost feeding areas, as well as a bias in the fluke coloration proportions of humpback whales from the CG summer aggregation, our findings provide additional information to the current knowledge on ESP humpback whales, and supporting evidence of a third mid-latitude feeding area in the Chiloense Ecoregion (Hucke-Gaete et al 2013). If the current description of population structure among these austral summer aggregations is correct, our result is also relevant in the context of population trend assessment and conservation.…”

“…Despite the small number of identified whales in northern Chilean Patagonia, these results suggest that at least part of the ESP humpback whale population also migrates to Corcovado Gulf and remains in northern Chilean Patagonia (43°S) throughout the summer and early autumn. Although blue whales are the primary re search focus in the CG (Hucke-Gaete 2004, Hucke-Gaete et al 2004, some residence time data indicate that humpback whales remain up to 32 d (Haro 2009, Hucke-Gaete et al 2013.…”

“…Photo-identification efforts from boat-based surveys resulted in 34 individual whales identified by their fluke coloration pattern in the CG region. Ten of these individuals were re-sighted within a maximum of 5 yr, resulting in a 31% return rate (Haro 2009, Hucke-Gaete et al 2013. Although the effort dedicated to humpback whales in CG has fluctuated over the years, the available evidence suggests that this humpback whale aggregation is smaller than the FA aggregation.…”

“…Likewise, an increasing number of humpback whales exhibiting feeding activities have also been observed during the austral summer/fall months in the Corcov-ado Gulf (43°53' S). Corcovado Gulf is located 1080 km north of the Magellan Strait, suggesting that this corresponds to another discrete feeding area for this population (Haro 2009, Hucke-Gaete et al 2013). An alternative interpretation would be that the Corcovado Gulf may correspond to a transitory area during the whales' migration further south to the Fueguian Archipelago or the Antarctic Peninsula.…”

Short‐term recovery of humpback whales after percutaneous satellite tagging

“…The eastern South Pacific humpback whale population or breeding Stock G (International Whaling Commission ) is distributed along neritic waters from northern Peru (∼4°S) to Costa Rica (∼12°N) with known breeding sites of concentration in northern Peru (Guidino et al ), Ecuador (Scheidat et al , Félix et al ), Colombia (Flórez‐González ), Panama (Rasmussen et al , Guzman et al ), and southeastern Costa Rica (Rasmussen et al ). The stock has ≥3 summer destinations for feeding, particularly in the Patagonia Fjords, the Magellan Strait, the Corcovado Gulf in Chile, and the Gerlache Strait (64°30′S, 62°20′W) in western Antarctic Peninsula (Gibbons et al , Stevick et al , Acevedo et al , Hucke‐Gaete et al ). The entire population uses nearly 9,000 km of coastline and is estimated at approximately 6,000–7,000 animals (Félix et al ).…”