Changing Whale and Shark Sightings from Summer to Fall

By Sharon Hsu

For many people, fall in New England conjures up images of change: leaves changing from green to red and gold, and summer humidity falling away to cooler and drier weather. For our aerial observers, this theme of change is also evident in our fall surveys. As summer transitions to fall, we begin to notice changes in whale distributions in our survey area as well as in the number of shark sightings.

Fall foliage seen from above
Fall foliage as seen from the survey plane.

This summer, we observed many humpback whales bubble-feeding south of Martha’s Vineyard. In fact, we documented an aggregation of over twenty humpbacks in this area. However, as the fall months of September, October, and November approach, we usually begin to see a shift of humpback presence away from Martha’s Vineyard and toward Nantucket Shoals, an area also utilized by right whales during this time. Here, we no longer see the same humpback bubble-feeding behavior that’s common in the summer. Instead, both humpbacks and right whales are likely subsurface feeding and can be found in close proximity to one another. Occasionally we are surprised by how closely they overlap, as the two species are typically thought to feed on different prey. In fact, on a September survey, we saw a humpback surface right next to a small group of right whales!

Right whale Catalog #3832 and a humpback whale spotted in close proximity in Nantucket Shoals.

But whales aren’t the only ones to show summer-to-fall changes! Each summer, shark sightings become more frequent off Martha’s Vineyard and Nantucket. The most common summer sharks we see are blue sharks, and in more recent years, hammerhead sharks—likely brought in by warmer waters. This past summer, we sighted 77 blue sharks and 95 hammerhead sharks! However, as fall approaches and the temperatures begin to decrease, we also notice a decrease in shark sightings. In the summer, we also sighted 18 basking sharks—the second-largest shark species—however, we usually see more of these sharks in the cooler shoulder seasons along their migratory routes. Stay tuned for a more detailed basking shark observation and other fall aerial survey updates!