Seabirds, marine mammals, and science at sea
By Jenny Woodman
The sun is shining, but strong winds and high seas keep conversation to a minimum on the flying bridge of the NOAA Ship Bell M. Shimada. Perched three decks above, the bow of the boat seems at times to bounce on the water below as she comes up over the crest of the whitecaps. Waves regularly explode over the bow, some freckling the glass windshield with droplets of icy cold water.
The wind roars.
Wildlife surveys such as this one are dependent on visibility, sea state, wind, and light. Yesterday afternoon’s transect from east to west pointed the observers into the sun, so glare and high seas made sightings challenging. Their goal is to sample as much wildlife as possible, but it isn’t realistic to count everything, so they collect subsamples.
It’s Sunday on day seven of a cruise monitoring seabirds and marine mammals off the coast of North-Central California National Marine Sanctuaries (Cordell Bank, Greater Farallons, and Monterey Bay). These Applied California Current Ecosystem Studies (ACCESS) cruises take place three to five times each year.
There are two methods used for surveying wildlife on this cruise: line-transect and strip-transect. Jan Roletto, chief scientist and research coordinator for the Greater Farallones National Marine Sanctuary, explains that the marine mammal observers use a line-transect method.
The location of the wildlife in the ocean is determined with relative precision using: height, which is based on eye-level from atop the flying bridge; distance, which is measured using the reticle markings on the binoculars; and, the seabird or mammal’s bearing relative to the bow of the ship.
“It’s all just basic geometry,” Roletto said.
The ship maintains a consistent speed during transect lines, and the computer logs GPS coordinates frequently. Wildlife are logged by Taylor Nairn, data manager for Greater Farallones Association (GFA) and data logger on this cruise. Then, the calculations are automated using software developed by NOAA Fisheries.
Roletto monitors the 90-degree quadrant from the bow to the port side of the vessel and Dru Devlin, research associate for GFA, observes from the bow 90 degrees to the starboard side.
While Roletto and Devlin count the mammals, Kirsten Lindquist uses a strip-transect method and counts 100 percent of the seabirds in a 200-meter strip in front of her. “We use strip-transect lines for things that are numerous and line-transects for things that are more scarce,” said Roletto.
By monitoring population densities, prey availability, and their locations, the team can help identify trends over time and look for locations where human activities might be harmful to the wildlife.
Earlier in the week, Lindquist has counted thousands of seabirds during one transect line. Several of the species observed, such as Common Murres and Sooty Shearwaters, tend to float out in the open water together in very large numbers.
Today and yesterday, the weather is keeping sighting numbers low. They’ve spotted a few Northern Fulmars and Rhinoceros Auklets alongside a small number of unidentified whales, Risso’s dolphins, Dall’s and harbor porpoises.
Black-Footed Albatross are more abundant than previous days. They are built for this weather. It is mesmerizing to watch them float and soar on winds that make it challenging for humans (at least for this human) to walk the distance from the top of the stairs to the shelter of the windshield on the upper observation deck.
Albatross are very large, with wingspans up to 85 inches. They are classified as tubenoses, because they have very large tubes above their beak; these tubes are connected to salt glands over their eyes which enables them (and all other seabirds) to drink saltwater. These seabirds have an incredible sense of smell, aiding in the detection of prey at great distances.
The albatross we are seeing here off the coast of California have traveled from their nesting colony in the atolls of Northwestern Hawaiian Islands. The almost 6000-mile roundtrip journey will take up to two weeks by the time that they fly here, gorge, and then return home to feed their chicks.
Albatross ride these powerful winds in a process called dynamic soaring, flying up to 80 miles an hour without flapping their wings, therefore conserving energy for their long journeys. Engineers have studied these birds in order to design better aircrafts.
These constantly changing waters—smooth and glassy one day, powerful and fierce the next—seem to offer something for all who come here.
Jenny Woodman, Proteus founder and executive director, is a science writer and educator living in the Pacific Northwest. Follower her on Twitter @JennyWoodman.
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