Seattle Aquarium Community Engagement Manager Darcie Larson recently had the opportunity to assist scientists from NOAA’s Northwest Fisheries Science Center with their research on the local endangered orca population, the Southern Resident killer whales, which consist of J, K and L pods. These whales are frequent visitors to the inland waters of the Pacific Northwest and are even sometimes seen in Elliott Bay, right in the “backyard” of the Seattle Aquarium. NOAA has identified three main threats to this population of approximately 85 whales: scarcity of food (salmon); high levels of contaminants from pollution; and disturbance from vessels and sound. During the summer, the Southern Resident pods can often be found around the San Juan islands, about 100 miles northwest of Seattle. In the fall and winter, the whales follow salmon runs into central and southern Puget Sound, bringing them close to Seattle. Researchers obtain a permit to follow the whales in a boat flying a yellow flag, allowing them to come much closer than the 200-yard minimum distance that other boaters are required to maintain. From the research boat the scientists collect a variety of information about the whales to determine if recovery efforts are helping or what other efforts should be made.
Assisting the researchers allowed Darcie to get a firsthand look at all the work that goes into studying these amazing animals, and share the experience and knowledge she gained with others through her work at the Seattle Aquarium. Learn about Darcie’s experience in this 3-part blog.
Part 2: Still Waiting For Whales
While we were waiting for whales to show up, I was trained in how to record data while on the boat. I would note any sightings of cetaceans, a group that includes whales, dolphins and porpoises. Not pinnipeds—seals and sea lions we could just admire from afar but did not need to record. For any sightings, we would take “way points” on the GPS and then fill in the latitude and longitude when we got back to shore. Also the sea state would be recorded using the Beaufort Scale—from 0 for flat calm to a Beaufort 6 if it was really stormy. We were all hoping for 0 or 1 since not only would it be way more comfortable on the boat, it would also be easier to see and follow the whales.
If we did encounter Southern Resident killer whales we would attempt to attach a tag, using suction cups, to one of them. In that scenario, I would switch to a different data sheet and prepare to take data every five minutes, including the speed of the boat, orientation of whales to the boat, number of boats within 200 and 400 yards, with motor and without, the identification of the whales, and other information about what the whales were doing. If certain behaviors were observed that indicated the whales might be going after salmon, we would record any “cues”)—things like fast swimming and direction changes—and look for prey samples (scales or salmon bits). While following the whales we would also look for fecal samples (that’s right, whale poop!). Such samples can be analyzed in NOAA’s labs to determine what type of salmon the orca ate and even which river it came from. This information is very important since lack of salmon is one of the three main threats to the future survival of the Southern Resident orcas.
A major component of this research is the use of DTAGs, or digital acoustic recording tags. DTAGs are a technology developed by the Woods Hole Oceanographic Institute to study how marine mammals respond to underwater noise while they’re actually underwater. (Most research on marine mammal behavior is limited to those brief moments when researchers can see them at the surface—I once heard a whale researcher compare it to “trying to study an elephant through a keyhole.”) These devices, about the size of television remote controls, are placed with long poles on the backs of whales to collect data, and held in place by suction cups.
Tags are set so the suction cups’ seals break after a certain amount of time. When the tag pops off, it floats and emits a VHF radio signal that allows the researchers to track it down and retrieve it. Once it’s retrieved, the researchers download the data and come back the next day to try it on a different whale. If a DTAG was deployed, we would record which tag and what frequency the tag would be broadcasting on.
DTAGs contain various sensors including a hydrophone that records any vocalizations the whale makes along with whatever ambient noise is in the environment (such as boat engine noise); a time-depth recorder; and an accelerometer to record the movements of the whale in 3-D. Other tagging studies have been done on killer whales, but the opportunity to record sound and the 3-D movements of the whales as they navigate around boats and hunt for salmon is what makes this DTAG study unique.
Orcas and other toothed whales use echolocation to navigate underwater, where it can be very dark. They emit echolocation clicks, and the sound bouncing off objects in their environment allows them to detect fish, rocks and boats; they’re basically “seeing” with their ears. They also communicate with their family members in the pod using complex vocalizations which some experts believe is a killer whale language. Since sound is so important to killer whales, learning about how they might be affected by the noise of boats in their environment is important and can help us understand how to best protect these endangered animals. Imagine you are in a noisy room full of people, and trying to carry on a conversation with the person next to you. Then someone turns on a vacuum cleaner. You might have to really raise your voice for the person next to you to understand you. Scientists are looking at the effect this effort might have on the whales.
Some of the challenges of collecting data on a moving boat include making sure your data sheets don’t fly away; keeping track of what the researchers are saying so you can record anything important like an interesting whale behavior; and counting the number of boats and estimating how far away they are. The whales may change speed or direction at any moment, or they may dive for a few minutes and then you don’t know for sure where they will surface. The researchers must also keep track of which whales they’re with—identifying them by their dorsal fin and saddle patch, a light marking just behind the dorsal fin that is unique to each whale. During the summer around the San Juans there can be dozens of boats that the whales (and the researchers) must navigate around, including commercial whale watch and fishing boats, and private motorboats, sailboats and kayaks. This work may sound like a fun day out on a boat watching whales but it’s really far from it. The crew comes back exhausted!
After half an hour or so of instruction, I felt (mostly) ready to collect data–and figured I’d pick it up as we went along. I was encouraged to ask lots of questions. Then it was time to wait on those whales!
To learn more about orcas, visit our Orcas in Puget Sound webpage and stay tuned for the next blog post in this 3-part blog series.
All photographs taken under federal research permits and except where noted are courtesy of NOAA.