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.
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| Map of whales spotted off of Southeast Farallon Island from July 2-8 2015 during standard surveys. Each dot represents a whale sighting, with the size of the dot corresponding to the number of individuals in a group. While the exact location represents an estimation based on reticle, this map shows the sheer number of whales concentrated in the Gulf of the Farallones. |
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 4th
were 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.
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| The left image represents humpback whale sightings and the right image represents blue whale sightings from July 2-8, 2015 from Southeast Farallon Island during standard surveys. The number of humpbacks is much larger, but there are still a large number of blue whales around. |
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
