July 15, 2015
As an intern working for Point Blue Conservation Science, I spend the majority of my time focused on the seabirds of the Farallones, but cetaceans are also an important part of the research undertaken here. Over the past two months, I have spent many hours cataloging the numbers of whales and dolphins around the islands.
The 4th of July this year was particularly eventful with 92 humpback and 21 blue whales seen in an hour! This was the highest record of the year for the more common humpback whales and a narrow 2nd highest for the less common blue whales. To add flavor to these huge numbers were three Risso’s dolphins, 18 Pacific white-sided dolphins and the first fin whale record of the year. Dozens of spouts were visible at a time, those of the giant blue whales dwarfing those of the humpbacks. The huge open mouths of the humpbacks would break the surface in groups, baleen briefly visible before the animals disappeared underwater.
Numbers of both humpback and blue whales have climbed from single digits in mid-June to these unprecedented numbers. This increase is likely in response to available food in the area, in this case krill. Food is patchy in the ocean and animals that rely on it have to be able to travel great distances to find it. When it is abundant, feeding frenzies occur where many species converge on an area to access the resource. We commonly see small scale frenzies involving local pinniped and seabird species alongside migrating shearwaters and the odd albatross but usually not involving the great whales. Krill in great swarms represent one of the richest sources of nutrients and energy in the Gulf of the Farallones region and a virtual puree of these small crustaceans has attracted the whales to the area. The krill blooms are not static and the whales move with them. As evidence of this, Point Blue conducted an ACCESS cruise at the end of June where they sampled the water column in transects that ran right by the island. During this cruise krill was not abundant and large numbers of cetaceans were not reported. Additionally, the huge numbers first seen on July 4thwere south of the islands, whereas the next day they were to the west and on the 7th they were predominantly north-west of us and far away.
In order to document cetaceans around the island, we use hour-long standardized whale surveys, conducted from the lighthouse, highest point of the island at 90m above sea level. They are weather dependent, and as fog shrouds the island more often than not, a comprehensive survey can only take place when visibility extends to at least (7 miles?) with low wind so the animals can be seen amongst the waves. Whenever the conditions are good, a member of the research team climbs Lighthouse Hill and methodically scans the full circle of the horizon using a spotting scope. To record data, we use a tablet with Spotter Pro, an application developed and tested by Point Blue and other organizations concerned with marine conservation. We count individuals and record their species, as well as any behavior observed. The humpback whales are particularly entertaining to watch with frequent breaching (this is where the whale launches itself mostly out of the water creating a huge splash), tail slapping, diving, travelling and feeding among others. By pointing the tablet at the whales we can record the bearing and this is important because once we add a distance from the island and our GPS coordinates, the position of the animal can be accurately plotted on a map.
The data we collect show the areas used by whales traveling along the California coastline as well as where they congregate to feed. These maps can then be studied side-by-side with those of shipping routes in the Gulf of the Farallones and have in the past been instrumental in modifying these routes to lower the chance of ships striking whales. Not only is it a great experience to see such magnificent creatures, but the data is also used for conservation purposes. It was a great way to spend the 4th of July, it beats fireworks any day.
-Written by 2015 Point Blue seabird research assistant Edward Jenkins