Humpbacks, warm water,  and El Niño

For the last 5 years as part of our Baja Whale Ecology Program EPI has been making voyages with students up and down the Baja coast between Loreto and Los Cabos assisting local scientists to observe some of the 33 cetaceans that inhabit the Gulf of California. During this time we have come to see patterns in the distribution of whale sightings over different latitudes. For example, when we are navigating around Loreto, it is almost guaranteed that we will see Blue Whales and Fin Whales. As we navigate to the south toward Los Cabos, Humpback Whales start to dominate our observation time.

This year we are seeing something different. During our instructor training, in under two days, we were lucky enough to observe more than 15 whales in the Bay of La Paz, just minutes by boat from our EPI Campus. What caught our attention, however, was that all of these individuals were Humpbacks. Don’t get me wrong, we enjoyed the show. The Humpbacks were putting on a spectacular demonstration of breaches, pectoral fin slaps, and fluke displays. Nevertheless, while we had witnessed this before in the area, in past years Humpbacks usually composed just a fraction of our other sightings including Fin Whales, Pilot Whales, and even a group of over 80 Sperm Whales floating lazily at the surface for several hours. We were left wondering why we had seen exclusively Humpbacks this time around.

This past week scientists finally announced that we are indeed in a El Niño year. This is a phenomena that occurs naturally when winds in the Pacific Ocean diminish for an extended period of time. Currents at the ocean surface slow down and water temperatures rise. Researchers substantiated this by taking temperature readings at depths of up to 800 meters from aboard one of the commercial ferry boats that runs between La Paz and the Mexican mainland.

My personal view is that there definitely is a correlation between whale sightings and water temperature. Our first student Whale Ecology Program voyage just returned to port on Saturday. They reported water temperatures of 22 degrees Celsius (about 2 – 4 degrees higher than average), and a significantly higher than normal abundance of Humpback sightings so far north.

It will be interesting to find out whether this is just an anomaly, or if our subsequent student groups make similar observations. It’s early in the season, so one can never tell. What do you think? Send us your thoughts!