Article,
Environmental drivers of persistent humpback whale Megaptera novaeangliae feeding events in a Mexican breeding area
Affiliations
- [1] La Orca de Sayulita, Sayulita, Nayarit 63728, México [NORA names: Mexico; America, Central; OECD];
- [2] Murdoch University [NORA names: Australia; Oceania; OECD];
- [3] Ecología y Conservación de Ballenas, Puerto Vallarta, Jalisco 48325, México [NORA names: Mexico; America, Central; OECD];
- [4] Happywhale, Santa Cruz, California 95060, USA [NORA names: United States; America, North; OECD];
- [5] Southern Cross University [NORA names: Australia; Oceania; OECD];
(... more)
Abstract
Humpback whales Megaptera novaeangliae typically fast for several months in low-latitude breeding areas. Here we report on persistent feeding events during 5 wintering seasons between 2013 and 2020 in a known upwelling region of Banderas Bay of the mainland Mexico breeding area. In total, there were 76 unique feeding events documented (group size = 1 to ~100 individuals), involving 201 photo-identified whales, of which 18 were documented feeding in multiple years. The most prolific years of documented feeding in 2017 and 2018 (based on number of reports/individuals photo-identified feeding) followed the strongest marine heatwave ever recorded in the North Pacific. Whales documented feeding in Banderas Bay had significantly shorter mean sighting histories (2.3 yr) than a non-feeding sample (8.7 yr) and were reported to be of small size, suggesting they were predominantly younger whales. Most high-latitude recaptures of Banderas Bay feeding whales were in more northern North Pacific feeding grounds (50.8% were resighted in Russia, Alaska, and northern British Colombia, Canada). A binomial general linear model revealed a significant relationship between the probability of whales feeding in Banderas Bay and sea surface temperature (SST). Specifically, feeding consistently occurred in years of lower than average winter SST (<25°C), associated with La Niña years of the El Niño Southern Oscillation (ENSO). We conclude that feeding of humpback whales is now a predictable occurrence in the upwelling region of Banderas Bay in years that ENSO fluctuations lead to lower regional SST. The magnitude of several years of low-latitude feeding events reported here was likely influenced by climate change induced marine heatwaves that occurred during the study period.