Photo from the Center for Whale Research. One of the Conservation Canines doing his job finding southern resident killer whale scat.
Every time I go to the Seattle Tacoma airport, I play a game that distracts me from my travel anxiety: I Spy a dog. Ten years ago I didn’t play this game— a dog at an airport was a rare sight— but nowadays a trip to SeaTac is not complete without seeing a service dog walking with its owner, a therapy dog on someone’s lap, and a security dog sniffing luggage of travelers.
Dogs have always had jobs. They were bred for jobs, and only recently did their job transition from things like “bird dog” and “herding dog” to full time companions. Some dogs have taken this career change in stride. In Seattle, it’s rare to go to a brewery and not find a chill pup laying by its owner, just happy to be there and receive pets and attention. Other dogs still have jobs, like those I see at the airport. Therapy dogs keep their owners steady in times of stress, and airport security dogs are trained to detect weapons and narcotics.
There are those dogs, however, don’t conform to a standard domestic life, and aren’t well suited for more restrictive jobs that require calm demeanors. These dogs have energy that needs an outlet most owners can’t provide on a daily basis. They want to move constantly and obsessively. A lot of the time these dogs end up in shelters, being too much for their owners to handle. But what they really need is a career change.
Due to their resilience, unbounded energy, and strong noses, dogs have made invaluable helpers in all sorts of conservation studies. They’re becoming a popular tool for researchers, with several organizations popping up around the world that train dogs for conservation research. One organization, Working Dogs for Conservation, looks specifically for “bad” or “crazy” dogs in shelters, and trains them to jobs like detecting dangerous invasive species, sniffing out illegal animal contraband to reduce poaching of endangered species, and even detecting diseases in livestock.
In Seattle, Dr. Sam Wasser (Center for Conservation Biology, University of Washington), and dog training expert Barbara Davenport (PackLeader Detection Dogs) founded Conservation Canines. They train dogs to sniff out the poop, or scat, of endangered species over large landscapes. Their ideal detection dog “is intensely focused and has an insatiable urge to play”— and they will go to great lengths to play. These dogs spend their days hiking in search for scat, and when they find a sample, they get rewarded with a play session and their favorite toy.
The scat samples they detect are then analyzed in the laboratory, where researchers can extract genetic, diet, chemical, and hormonal data from the poop to learn a lot about the species. Conservation Canines have even taken their work to the sea, training dogs to detect endangered southern resident killer whale poop. That’s right, they bring their dogs on boats, where they can sniff out orca poop over great distances in the ocean. These samples are used by all sorts of research working to conserve this iconic orca population, including my own research on parasite infections in orcas— studies that would be near impossible without the help of a specially trained dog leading the way to the samples.
The unifying feature of these organizations is that they see the potential in rescue dogs and provide them with a new life where they get to go to a fulfilling job for the payout of playtime. I have heard the phrase “there are no bad dogs, just bad owners” in the past, but maybe replacing “owners” with “jobs” would be more appropriate as these former misfits become the heroes of endangered species conservation.
There are indents on my nose, my hair smells faintly of ethanol, and I am actively working on realigning my spine after several hours hunched over a microscope. I have just wrapped up a fish dissection, but not a normal fish dissection of a fresh or even thawed fish. This fish was caught in 1985. Once captured, it was fixed in formalin and then stored in ethanol, living in a jar in the Burke Museum’s fish collection at the University of Washington for the last 35 years. This dissection is a small piece of the Wood lab’s effort to reconstruct the past of Puget Sound, and the parasites that lived in it. Each fish preserved contains a snapshot of what parasites infected it when it was caught and subsequently stored in ethanol, to live on a shelf for eternity. By dissecting the species commonly caught in Puget Sound and stored over the past century (that’s right, 100 year-old fish!) we are able to see how parasite diversity has changed in the region.
This has important implications for the fish that these parasites infect. Some of the parasite species found in fish use that fish as their definitive host; they’ll live in that fish for the rest of their lives. Other species, however, use the fish as a stepping stone--or intermediate host--to get to their ideal definitive hosts. These parasites wait until their intermediate host gets eaten, hopefully by a definitive host that they can infect for the rest of their lives. The parasites found in the fish represent the transferable parasites that were inhabiting the environment at that time, available to be eaten by a definitive host.
A group of these parasites are parasitic nematodes (worms) of the family Anisakidae, or anisakids, which I discussed in my blog post “Anisakid risk to endangered marine mammals.” These nematodes have multiple life stages, in which they depend on different hosts. Their first host, or primary host, is a copepod, which then gets eaten by a small fish or squid. In this second host, the nematode encysts in the muscle and waits to get eaten by the next biggest animal, hopefully a marine mammal (a whale, dolphin, seal, sea otter, or sea lion). Unfortuantely for the worm, from there it gets eaten by another fish. But evolution prepared them for this! Anisakids can keep getting eaten by fish and encysting them until they finally reach a marine mammal. Then, once they finally reach a warm-blooded host, they inhabit the stomach or intestine and reproduce. Those eggs are then sent out into the marine environment through the host’s feces, where they can get eaten by a copepod and the whole life cycle can begin again.
Aniskaids might play a bigger role in marine mammal health than previously thought. Once in the intestinal tract of a marine mammal, anisakids absorb nutrients from the host, taking up energy that would otherwise be used by the host alone. At larger burdens, large amounts of energy can be taken from the host, effectively acting as an energy sink. The whale or seal needs to eat more to account for this energy lost to its parasitic stowaways. But for at-risk or endangered species like the southern resident killer whale, which is already nutritionally stressed, parasitism by these nematodes may represent an additional stressor inhibiting the recovery of the species by acting in concert with other stressors.
In the lab today I was dissecting herring. Herring are an important forage fish in the Pacific Northwest. They form large schools and can be found in open ocean as well as bays. Herring are eaten by humans, fish, and birds, and they also make up a large part of the diet of some marine mammals, including whales, seals, sea lions, and porpoises. They form a foundation of the food web, so that the parasites that they harbor can continue on to a marine mammal, even if they are not consumed by one directly. By assessing how the abundance of anisakid nematodes has changed in herring and other fish, both small and large, that are common prey to marine mammals, I am uncovering how the risk to anisakid infection has changed locally over the past century.
While we are still in the dissection stages and not the analysis quite yet, I think we may see an increase in anisakid abundance. Marine mammals are key to the spread of anisakids in the marine environment, and surprisingly enough some marine mammals in this area have been increasing in number since protections were put in place in the 1970s (think of the skyrocketing populations of sea lions and harbor seals in the area). With more definitive hosts shedding eggs into the environment, the likelihood of infection of fish and subsequently of other mammals increases. I expect that this will be evident through the historical record we’re currently examining.
It is important to determine what parasite abundance in the ecosystem was like in the past because it provides context for what we see today. A component of my research is assessing how parasitized marine mammals in the area are now, and if parasites are likely impacting the health of marine mammals more than they were in the past. If we don’t know what the past was like, we can’t tell if marine mammals today are any worse off now than they were before, especially the at-risk ones like the endangered southern resident killer whale. If at-risk species are facing a more significant threat from parasites today than they were in the past, then those threats could be incorporated into their management. Parasitism may play a role in the recovery of at-risk marine mammals, but without digging in and figuring out if this is a new problem or status quo, we won’t know.
Until last year, my research revolved around whale foraging behavior. I studied the foraging behavior of humpback whales for my masters and spent several summers in the San Juan Islands studying southern resident killer whale behavior in response to shipping noise with Oceans Initiative. When I met Chelsea Wood, a parasite ecologist at the University of Washington, while scoping out PhD advisors it dawned on me that there was a whole other scale of foraging ecology to consider in whales— that of the parasites living within them.
I had worked with sick marine mammals before and assisted on a handful of necropsies at that point. Parasites were relatively commonplace, but generally not the cause of rehabilitation for the sick animals or death for those we necropsied. I had grown accustomed to ignoring parasites and assuming their effects were negligible. But after meeting Chelsea, it was clear that parasites may play a bigger role in animal health and survival than I had given them credit for. I had been studying southern resident killer whales with Oceans Initiative for several years, working on assessing the impacts of a suite of threats to the population. I thought more about the role parasites might play in an endangered species like the southern resident killer whales, whose recovery is inhibited by multiple stressors. For marine mammals that are already facing a multitude of threats, parasites could be an additional burden that might make the difference between a healthy and a sick animal.
Marine mammal parasites are nearly as widespread as their hosts. Parasitic nematodes of the family Anisakidae, or anisakids, are transmitted to marine mammals through the fish that they eat. Anisakids travel up the food web from copepods to fish or squid until they reach a marine mammal, their definitive host. They inhabit their host’s intestinal tract, reproducing and sending their eggs back into the ocean via their host’s feces to continue the cycle. These parasites can infect a wide range of fish species, leaving many marine mammals vulnerable to infection if their prey harbor anisakids.
There is evidence that anisakids are on the rise around the world. This led me to wonder, are these parasites increasing in the prey that marine mammals eat? And could the most vulnerable marine mammals be at risk to increases in parasitism? This seemed like an important question to address from a recovery and management standpoint. There are vulnerable marine mammals around the world. If these species are also facing an increase in parasitism, that may be an added stress impacting their rate of recovery.
The first chapter of my PhD has focused on answering these questions in some of the most at-risk species— those listed as threatened or endangered in the Endangered Species Act and the IUCN Red List. My lab-mate Evan Fiorenza recently completed a major meta-analysis of the publications on anisakid prevalence over the last 60 years. I compared the ranges and diet species of all IUCN listed species and ESA listed populations, resulting in 14 populations that overlapped with this meta-analysis dataset, ranging 30 years. I also subset the data to look at the species with the most data to see if there was a trend in any of the most well-represented diet species, grouped by the mammal that eats them.
As I am still actively analyzing the data, it is too soon to say whether there has been a change in anisakid abundance in the prey that endangered marine mammals are eating. That being said, I am excited to be presenting my preliminary data and analyses at the World Marine Mammal Conference in Barcelona this week. With any luck, I will be able to talk to some of the experts on these endangered marine mammals to gather more information about their diets to improve the resolution of my study. When I return, I plan to work on increasing the scope of my study to include species listed under Canada’s Species At Risk Act (SARA), and working with the experts at Oceans Initiative to improve range estimates of these species. But for now, I am excited to soak in new information more from the world’s marine mammalogists over the next week.