I've spent a lot of Thursdays on this ferry with a pair of headphones plugged into a hydrophone feed, listening for a family of orcas that the Pacific Northwest has been watching for fifty years. The water is cold, the coffee is marginal, and the whales do not care what day it is — but the ferries do, and that turns out to matter more than I expected.
What does orca whale song research in the Salish Sea actually involve?
Most people picture a research vessel, a dramatic bow spray, and a scientist in foul-weather gear leaning over the side with a microphone. The reality is quieter and wetter in a different way. A lot of it is hydrophone data — underwater microphones anchored at fixed points throughout the strait — reviewed on a laptop in a corridor that smells like salt and bilge water.
The Salish Sea spans roughly 18,000 square kilometers of interconnected inland waters along the Washington and British Columbia coasts, including Puget Sound, the Strait of Georgia, and the Strait of Juan de Fuca. It is the year-round home range of the Southern Resident killer whales: three pods — J, K, and L — comprising 74 individuals as of the 2024 census conducted by the Center for Whale Research in Friday Harbor. That number has barely moved in decades. The population peaked at 98 in 1995 and has not recovered.
The research question I care about most is simple to state and hard to answer: when the noise gets loud, do the whales go quiet, or do they shout back? The answer is both, depending on conditions, and neither option is good for an animal that hunts by sound.
How do researchers identify individual orcas by their calls?
Every matrilineal family group within a pod shares a set of discrete calls — a repertoire of patterned vocalizations that is learned and transmitted across generations, not encoded genetically. J pod has its own repertoire. K pod has another. Within each pod, family lines carry subtle variations. A calf raised by its mother hears and learns the family's specific call set. When that calf grows up and has calves of its own, those calls pass on again.
This system is part of what makes the Southern Residents so unusual among cetaceans. Their cultural transmission of vocal behavior has been documented systematically since the 1970s by researchers including John Ford at the Vancouver Aquarium, whose call classification work remains the baseline most acoustic researchers still use.
In practice, identifying a call type from a hydrophone recording means comparing a spectrogram — a visual map of frequency over time — against a reference library. You look for the shape of the call, the frequency range, the internal structure. J pod's S1 call, a rising two-note pattern, is distinctive enough that an experienced analyst can identify it in under a second. The harder work is separating overlapping calls when multiple animals are vocalizing simultaneously, or when a distant freighter is pushing its engine noise through the same frequency band your orcas are using.
Why do J-pod vocalizations seem to spike on certain days — and why Thursdays?
The Thursdays thing is a joke I made to myself two years ago and have never fully walked back. The honest version is this: call rates in the J pod acoustic record correlate with ambient noise levels, and ambient noise levels in the Strait of Juan de Fuca correlate with vessel traffic patterns. Ferry departures and commercial shipping follow schedules. Those schedules have weekly rhythms. Therefore, acoustic windows — periods when the orcas can communicate without competing against engine noise — also have weekly rhythms.
Thursday happens to align with a relative lull in a particular ferry corridor I monitor. So on Thursdays, the feed is cleaner, and I hear more. The whales are not doing anything different. I am just able to hear what they are doing. The distinction matters, but it took me longer than I'd like to admit to make it cleanly.
The broader pattern is well-documented. A landmark study of Southern Resident responses to vessel noise found that whales increase call amplitude in the presence of vessel noise — a phenomenon called the Lombard effect, observed in birds, fish, and humans as well — and alter their call timing and path. The problem is that louder calling costs energy, and energy in a calorie-stressed population is not something you spend lightly.
What do hydrophones actually pick up, and how does the OrcaSound network work?
A hydrophone is a pressure-sensitive transducer — a microphone designed for water. Deployed at depth in the Salish Sea, a good hydrophone picks up Southern Resident calls from kilometers away on a quiet day. It also picks up boat engines, rain on the surface, bubble noise from aeration, snapping shrimp, and the low-frequency groan of the earth adjusting pressure gradients under the Pacific. Separating signal from that background is most of the technical work in cetacean acoustics.
OrcaSound is a live-streaming hydrophone network run by a consortium of researchers and volunteers, with nodes at locations including Orcas Island, Bush Point, and Port Townsend. The project streams audio publicly at orcasound.net and runs a citizen science program where non-specialists flag interesting events in the real-time feed. The data from those flags feeds into research that professional analysts do not have bandwidth to do alone.
I have spent a surprising number of hours listening to the Bush Point feed when I should have been doing something else. There is something about the quality of the sound in cold, deep water — the way a call carries and rings slightly before it drops off — that does not translate well to description. You have to hear it.
Why does the Chinook salmon decline matter to whale song research?
Because a hungry whale does not vocalize the same way a fed whale does. Body condition affects behavior, and behavior affects acoustics. The Southern Residents are dietary specialists in a way that surprises people: roughly 80% of their diet is Chinook salmon, the largest Pacific salmon species. They have evolved alongside Chinook over thousands of years. When Chinook populations crash — which they have, across most Salish Sea watersheds — the orcas follow.
Nutritional stress in Southern Residents shows up in multiple ways that researchers can track. Above-water observers photograph dorsal fins and bodies; a concave postdorsal saddle, visible fat loss behind the blowhole, indicates an animal not getting enough to eat. Below water, call rates and foraging behavior patterns shift. Animals in poor body condition spend more time in echolocation-intensive search behavior and less time in the social and affiliative calls — the longer, more musical vocalizations — that make up much of what casual listeners think of as whale song.
The population has experienced reproductive failure for years. Live calves are born and die within months. Necropsies trace the causes: malnutrition, toxicant load from legacy PCBs accumulated through the food chain, compromised immune systems. The acoustic research and the population biology are the same problem from different angles.
What does vessel noise do to communication, and how close is too close?
The current federal guideline under NOAA's SRKW recovery framework recommends vessels stay at least 400 yards from Southern Residents and not approach from directly ahead or behind. In practice, on a busy summer weekend in the San Juan Islands, compliance is inconsistent and enforcement is difficult.
What researchers have documented is that in high-traffic periods, the whales change their behavior in measurable ways: altered swim paths, reduced foraging time in productive areas, elevated stress hormone levels in fecal samples collected by detection dogs working from small boats. The acoustic signature of a whale under vessel pressure is different from one in a quiet stretch of water. Not always in ways that are immediately obvious — but in the data, consistent.
The challenge is that the same waterways the whales use are the ferry routes, the shipping lanes, the recreational corridors. There is no version of Southern Resident habitat that does not involve human traffic. The research informs what mitigation looks like, but the mitigation requires coordination across federal, state, provincial, tribal, and commercial actors that each have their own timeline.
How can someone who is not a researcher follow Southern Resident whale science?
OrcaSound is the most direct access point. The live hydrophone feeds are free, no account required, and periodically the audio quality is extraordinary. The Center for Whale Research publishes annual census data and individual whale profiles at whaleresearch.com — every known Southern Resident has a file, a photograph, a genealogy, and a life history. J35, known as Tahlequah, grieved her dead calf for 17 days in 2018 by carrying its body through the Salish Sea. Her record is there, along with the records of every member of her family.
The Whale Museum in Friday Harbor on San Juan Island runs volunteer programs, public talks, and a hydrophone installation visitors can interact with directly. If you are ever on the ferry to Anacortes on a morning when the fog is low and the water is flat, and you hear something come through the speaker in the passenger cabin that does not sound like any noise a ferry makes — that is a call from somewhere in the strait, relayed from a hydrophone, playing in real time. Pay attention to it.
If you want to talk about the Salish Sea, what the data from this year's census means for the K pod situation, or why I think the ferry schedule acoustics paper I've been drafting for two years is almost ready — I'm around most Thursdays. I'd save you a seat.
