Wildlife rescues may inform orca strategies
As the plight of Puget Sound’s southern resident orcas becomes increasingly desperate, with the population dropping from 98 to 75 in just 22 years, scientists are weighing the options of medical intervention. In part two of our two-part series The Orca Docs we look at how veterinarians have intervened with other animals in the wild, and how this might apply to the situation here in Puget Sound. [Part one, "When should medical experts intervene to save a killer whale?" is also available.]
Among all the endangered Great Apes in the world, only the mountain gorillas of Africa are in the midst of a population increase, and success has been largely attributed to a close connection with humans — allowing medical intervention when necessary.
Through habituation, gorillas often allow humans to get close enough to care for them. So far, however, the idea of conditioning wild orcas has been unacceptable. And, while gorillas can be immobilized in the forest with a tranquilizer dart, that method would not work for free-swimming sea creatures.
How gorillas were rescued from extinction could provide some ideas for saving the southern resident killer whales, according to Joe Gaydos, a veterinarian with the SeaDoc Society and a leader in the effort to develop medical records for the 75 endangered orcas.
One program, dubbed the Gorilla Doctors, is based at the University of California, Davis and may have some of the strongest parallels, said Gaydos, who made a trip to Africa to see the Gorilla Doctors at work. Both SeaDoc and Gorilla Doctors are affiliated with UC Davis. [Editor's note: Gaydos is also a member of the Encyclopedia of Puget Sound editorial board.]
Habituation to humans, rather than a condition to be avoided, is an important step in protecting mountain gorillas in Rwanda, Uganda and the Democratic Republic of Congo (DRC), said Kirsten Gilardi, director of the Gorilla Doctors program.
In the 1960s, American primatologist Dian Fossey was the first to study gorillas up close by mimicking their actions and vocalizations while exhibiting submissive behaviors. Eventually, the gorillas allowed other humans to get up close as well, leading to authorized tourist treks into gorilla country.
“There is not a doubt in my mind,” Gilardi said. “If gorillas had not been habituated to humans, they would be extinct right now. For one thing, tourism provides the stream of funding needed for park protection.”
The lessons of Rwanda
The 175-square-mile Virunga Massif, also called the Virunga Volcanoes Region, includes connecting national parks in the DRC, Rwanda and Uganda where about 600 mountain gorillas roam. That’s up from a population of 480 in 2010, a 25 percent increase. Another 400 gorillas live in Uganda’s Bwindi Impenetrable National Park.
All of the gorillas in Rwanda are considered habituated, along with up to 60 percent of those in the DRC and Uganda, according to Gilardi.
“Habituated animals are observed daily,” she said. “They are identified by wrinkles on their nose … and they all have names.”
Medical officials are alerted when a gorilla doesn’t look right. An animal may be limping, not eating or just not getting up from the “night nest” where it sleeps.
While it is illegal to hunt in the national parks, locals sometimes put out snares to catch young antelope or other small animals. The gorillas can get caught in the snares, which can cut off circulation to their legs or arms. They may be strong enough to tear the snare away from a tree, but the wire loop can remain tight enough for lasting injury. Many dozens of ensnared gorillas could have died without intervention over the past 30 years.
In September, the Gorilla Doctors team in the DRC received a report of a tight snare on a 6-year-old male gorilla who was in a group still undergoing habituation. The team went in, observed the situation and decided to intervene, despite the potential danger. It would be the first intervention with a semi-habituated group.
“We agreed that if we were successful in anesthetizing him we would cut the snare right away, in case the group got agitated and snatched the gorilla back,” Gilardi said.
Normally, when an animal is treated, samples of blood, feces, skin and hair are taken for a full medical assessment and DNA analysis. To maintain close bonds with the troop, gorillas are treated in the field rather than taking them to an animal hospital.
A major threat to the gorillas is disease, and they are vulnerable to many human pathogens. Tourists with any illness, even a mild cold, are not allowed to visit the gorillas. Park rules prescribe a distance of least 7 meters (23 feet) from the gorillas — a distance that is often violated when a gorilla chooses to move closer. In the DRC, tourists are required to wear surgical masks to reduce the risk of exposing gorillas to respiratory viruses.
In 1988, a group of mountain gorillas in Rwanda was observed to be coughing, and they had difficulty breathing. Too sick to eat, they stayed in their night nests all day. Six gorillas died, and blood and tissues revealed evidence of human measles in three of them.
After much consideration, a trial run involved eight gorillas who were vaccinated against measles using a dart gun. When no adverse reactions were seen, another 57 were vaccinated. None of the vaccinated animals got sick, and the outbreak came to an end. Without more tests, however, the actual effectiveness of the vaccine could not be confirmed.
One of the greatest fears today is the deadly Ebola virus. A vaccine has been developed and administered to high-risk people throughout Africa, but an infection among gorillas could be devastating to the population. Contingency plans, which could include vaccinating the gorillas, are being developed.
Gilardi sees many similarities between mountain gorillas and the southern resident killer whales: Both are highly intelligent, social animals that live in organized groups. Individuals are identified and well known to researchers. Both are loved by large numbers of people.
But there are big differences in the threats they face. Poaching, snares and habitat loss create problems for the gorillas, while lack of salmon, interference by boats and toxic chemicals lead the list of threats to orcas.
Developing detailed health records and even medical intervention may be appropriate for both gorillas and orcas, according to Gaydos of SeaDoc. Through habituation, gorillas often allow humans to get close enough to care for them. So far, however, the idea of conditioning wild orcas has been unacceptable. And, while gorillas can be immobilized in the forest with a tranquilizer dart, that method would not work for free-swimming sea creatures.
Dolphin health assessment
One example of how veterinarians might protect free-swimming marine mammals can be found with a population of dolphins in Florida.
In Sarasota Bay, Fla., scientists have been working closely with about 160 resident bottlenose dolphins that make their permanent home in the 56-mile-long waterway. What is known about the health of the Sarasota dolphins goes far beyond what is known about the southern resident orcas, although scientists see some parallels in the two situations.
Since 1988, scientists involved in the Sarasota Dolphin Research Program have been capturing and releasing dolphins to compile individual medical reports on about two-thirds of the dolphins in the bay. Knowing the health status of individual dolphins has increased the understanding of the population as a whole, according to program manager Randall Wells. Furthermore, the dolphins have served as sentinels for overall ecosystem health in the region. That mirrors some of the thinking in Puget Sound, where southern resident orcas are designated by the state as a “Vital Sign” for ecosystem recovery.
Capture efforts are generally undertaken in shallow bays within Sarasota Bay, which lies on the Gulf of Mexico along Florida’s western shoreline. Experienced handlers encircle the dolphins in a seine net and then bring them aboard a boat using a sling.
Examinations include weighing and measuring each dolphin. Ultrasound is used to check the conditions of organs, measure blubber thickness and determine if females are pregnant. Blood taken from the tail fluke and urine removed through a catheter provide information about the animal’s metabolic condition and immune function. Blood, blubber, skin and milk are tested for toxic contamination. Breath samples and swabs from the blowhole are checked for disease-causing pathogens.
In Sarasota Bay, the health assessment projects, held nearly every year, are scheduled for several days, during which time medical experts assess the full condition of roughly 10 percent of the dolphin population. Over five days this past June, more than 100 people — including 30 veterinarians and technicians — collected samples from 10 female and 10 male dolphins, including six animals sampled for the first time.
By most measures, Sarasota dolphins are doing better than Puget Sound’s resident orcas. No widespread health concerns have been identified in recent years, although at least five resident bottlenose dolphins in Sarasota Bay have died during a dangerous toxic algae bloom that began in August. So far, the toxic algae have been associated with about 130 confirmed deaths among dolphins in Southwest Florida, according to NOAA Fisheries, which declared an “unusual mortality event” at the end of August. A similar event in 2005 and 2006 killed about 190 dolphins. These numbers do not include the many dolphins that died but were not recovered — perhaps twice the numbers of those that were found.
Despite the toxic algae, identified as the dinoflagellate Karenia brevis, the population of resident dolphins has been growing, with 21 calves born in 2017. Another 11 were born in 2018.
Can dolphins get the measles?
One ever-present concern is the risk of a disease outbreak caused by dolphin morbillivirus, related to the virus that causes human measles. From 2013 to 2015, more than 1,600 bottlenose dolphins were confirmed dead along the Atlantic Coast from New York to the eastern shore of Florida. Many other dead dolphins were never recovered. All ages of dolphins washed up on the beaches, with more males than females. Many of the dead animals had lesions on their skin, mouth, joints or lungs. NOAA Fisheries declared it an unusual mortality event.
Bottlenose dolphins in Sarasota Bay appear to have gone through an outbreak of dolphin morbillivirus more than 40 years ago, based on blood evidence, according to Randall Wells, director of the Sarasota Dolphin Research Program. Since most dolphins in the bay have been born since then, they are considered highly vulnerable to the disease, having never been exposed to the virus and thus lacking a natural immunity.
When necessary, sick and injured marine mammals in and around Sarasota Bay are taken to a special hospital established in 1992 at Mote Marine Laboratory on the bay. Most of the animals treated at the Mote Dolphin and Whale Hospital have been found stranded on the beach. Some have been injured by boats or entangled in fishing gear. The hospital, with its extensive equipment, can provide a full range of diagnoses. As with other mammals, blood samples frequently provide the key to identifying and treating infections and metabolic problems.
To keep track of the entire resident dolphin population, trained observers spend about 10 days each month on the water, taking note of the dolphins they see, including any new calves that are born. As with killer whales, individual dolphins can be identified from a distance by the shape, size and markings on their dorsal fins. Such boat surveys date back to 1970, the beginning of the dolphin research program in Sarasota Bay.
The observation program is similar to that provided for southern resident killer whales in the Salish Sea by the Center for Whale Research.
The Sarasota health assessments and hospital programs are highly acclaimed by experts throughout the country, and many would like to replicate those efforts, especially for endangered species. But the challenges are quite different, depending on the species. Capturing and treating killer whales, for example, is entirely different from capturing bottlenose dolphins.
For one thing, killer whales can be three times as long as bottlenose dolphins and weigh more than 15 times as much, according to Foster, who has captured both dolphins and orcas throughout his career, which includes health assessment work on both species.
“Killer whales are a lot harder to catch,” Foster said. “They are in deeper water, and they are very smart.”
Killer whales can identify the noise of a particular boat and avoid it entirely if they feel threatened, he said. With either species, keeping the animal calm is more successful than a battle for control.
Research using captive whales
Studies of captive orcas, though controversial, are another resource for scientists. This includes studies of breath samples, a technique that has already started to show promise in the wild.
From 2006 to 2009, a team of researchers motored alongside all three pods of southern resident killer whales and captured droplets of moisture from the exhaled breath of identified animals. The breath samples were analyzed for bacteria, fungi and viruses, revealing more than 50 pathogenic organisms in their respiratory systems.
It remains unclear how the organisms may be affecting the health of the individual whales. Some orcas may have developed immunity to some pathogens, but their immunity could become compromised by toxic chemicals in their system, combined with a lack of food and stress related to finding their next meal. Since those conditions are very real, individual whales could be susceptible to a number of diseases. They could also be exposed to dangerous new pathogens released into the Salish Sea through stormwater and sewage effluent.
Vaccines now used to reduce the risk of extinction in Hawaiian monk seals
For critically endangered animal populations, experts worry that a highly infectious disease could be the final nail in the coffin, forcing the species into extinction. That’s one reason why federal authorities approved the development and deployment of a new vaccine to ward off the deadly morbillivirus among Hawaiian monk seals.
While the research into whale breath has raised alarms about health risks to orcas, it has also proven that breath samples could be a minimally invasive way of getting a biological sample from an individual animal. Although breath samples are clearly not as good as blood samples, researchers are trying to determine if droplets from a whale’s blow can be used to identify hormones, enzymes and other metabolic chemicals that can provide clues to an animal’s health.
Medical experts working at SeaWorld hope that they can help refine and perfect the process. They have begun taking breath samples of their captive killer whales in a project that could one day determine whether an orca is healthy or sick by examining its breath alone, according to Hendrik Nollens, lead veterinarian for SeaWorld parks.
SeaWorld staffers regularly take blood samples from the orcas, who are trained to present their tail flukes and hold still during the procedure A recent study examined 20 years of blood samples — more than 2,100 samples in all — to describe the normal range of various blood parameters for orcas of various ages.
Many people question the ethics of confining killer whales in tanks at marine parks. Captures for aquariums contributed to a decrease in the southern resident population prior to 1976, after which time the population generally increased over the next 20 years. The more recent decline, starting around 1996, is blamed on lack of food, toxic chemicals and human disturbances. SeaWorld is no longer breeding or taking in new killer whales, and medical experts say important research conducted under controlled conditions would not be possible with wild orcas.
The health status of each of SeaWorld’s 20 orcas is well known, Nollens said. “The hope is that we can find molecules that are only present in a whale with pneumonia or liver parasites, for example. The easiest would be to find things that affect the lungs, but there might be some things that can pass through the blood and off-gas into the lungs.”
Even by including all 20 orcas in various SeaWorld parks, the sample size is too small to draw many conclusions about the meaning of chemicals in the breath, Nollens said. Over time, however, the number of samples will grow to include both sick and healthy whales, he noted.
Other health parameters
To increase the understanding of health risks for the southern resident killer whales, researchers and veterinarians are forming a team to pull together all sorts of information about each of the 75 surviving orcas. Information may include:
Gaydos, the veterinarian with SeaDoc Society, has been organizing the group and working on computer systems to aid in the sharing of information. One program that could be a model for data collection involves the endangered North Atlantic right whales on the East Coast.
Veterinarian Rosalind “Roz” Rolland, a researcher involved in the North Atlantic Right Whale Consortium, said sighting reports, as well as much scientific data, have been collected from more than 200 people and organizations. They include researchers, conservation groups, government agencies, shipping companies and fishermen.
Protecting the intellectual property of researchers is an important part of the effort.
“We have a data-access-sharing protocol,” she said. “If you want a set of data, such as findings in the Gulf of St Lawrence, you must write a proposal to the consortium board.”
The board reviews the proposal to see who has been doing similar research and might even recommend a collaboration with others, Rolland said. Pulling together diverse information from various sources allows for more powerful findings across a wider area of study.
“It’s an amazing example of cooperation among scientists,” Rolland said. “We all have the same goal in mind — to save the North Atlantic right whales from extinction. We are all pulling together to make that happen.”
Gaydos, who began discussing a similar collaboration three years ago for the southern residents, said he hopes that the organization will come together this year. The death of Scarlet and ongoing concerns for the other southern residents has increased the urgency of working together to save the whales.
This article was changed from its original version to clarify that gorillas are treated in the field, not in animal hospitals.
The Orca Docs: Part 1
When should medical experts intervene to save a killer whale?
How scientists are preparing to treat southern resident orcas that face starvation and risks of disease. Read Part 1.
Additional information about Puget Sound’s endangered southern resident killer whales is available on the Encyclopedia of Puget Sound’s ‘killer whales’ topic page.