An apocalyptic die-off of dolphins is occurring along the coastline of northern Peru. The reasons for the die-off are as yet unknown, though several culprits have emerged.

During February of this year reports appeared in a few newspapers that as many as 260 dolphins had washed ashore along the coast of northern Peru. On March 23rd I received an email from Dr. Carlos Yaipen Llanos, Lima-based director of the marine mammal rescue organization, ORCA Peru, stating he knew of thousands of dead dolphins in the same area.

The area of the Unusual Mortality Event (UME), as scientists refer to such mass mortalities, is along a bleak, desert coast, location of one of the most abundant fisheries in the world and the mating and feeding habitat for huge numbers of dolphins, sea lions and birds. If the mortality numbers reported were even close to accurate, this would be among the greatest UMEs ever recorded. In the United States declaration of an UME triggers funding for interdisciplinary teams of experts to investigate the situation. There is currently a UME in the Gulf of Mexico, likely resulting from the Deep Water Horizon oil spill.

I decided to throw the resources of BlueVoice behind an investigation into the cause of the die-off, but in order to justify that I needed to see the situation on the ground. I flew to Peru. When I arrived in Lima Carlos met me at the airport. We grabbed an overnight bus to Chiclayo, the closest city to the epicenter of the UME. Once there Carlos and I, along with three female assistants, packed into a four-wheel drive pickup and drove through the coastal town of San Jose to the beach. We headed north at low tide on a beach that was mostly firm. Our goal was to find the one thousand beached dolphins reported. We’d been told the greatest concentration of corpses was three hours drive north.

Within a few hundred yards we began to see dead common dolphins in ones and twos. Then Carlos saw a freshly stranded Burmeister’s porpoise calf. Some of the stranded animals were highly decomposed but this one was in such good condition we stopped to do a necropsy.

I thought of the years of life that had been denied this beautiful creature and what its death said about the state of our oceans.

As we progressed along the beach Carlos and his team performed necropsies on a couple more freshly stranded dolphins. The sight of a newborn common dolphin, umbilicus still attached, tongue grotesquely swollen, was wrenching. I thought of the years of life that had been denied this beautiful creature and what its death said about the state of our oceans.

We observed two species stranded. About 95 percent were long-beaked common dolphins (Delphinus capensis), which are drawn to the area to feed on the abundant fish of the nutrient-rich Humboldt Current that runs along Peru’s coast. The remainder are Burmeister’s porpoises (Phocoena spinipinnis), a species that feeds in deep water.

As we raced along the hard sand at the edge of the surfline, we cried out when we saw a dead dolphin. At first they came every couple minutes. But then we’d hit intervals when the cries would come nearly on top of one another. “Dolphin!” “Delphin!” ”Otro!” “Dos mas!” “There’s another one up by the dune.”

We tallied over 200 dolphins in just 45 minutes. Then we hit a length of beach no more than 100 yards long in which we found ten dolphins in varying levels of decomposition, indicating they had come ashore at different times.

The numbers continued to mount. By the time the rising tide forced us off the beach the count had reached 615, over a distance of 135 kilometers. We never did find the dense concentrations of stranded dolphins, just an endless succession of bodies over a long stretch of beach.

Carlos and I are conducting a study of Peruvian fishermen who eat dolphin meat. While illegal, this is commonly done and the authorities do not have the resources or will to prevent it. But Carlos had discovered something important. The fishermen who ate dolphin meat regularly have a disproportionately elevated incidence of diabetes. There is an established link between high levels of persistent organic pollutants (POPs) such as PCBs and endocrine irregularities. These include changes in the way the body uses sugar.

As the day wore on, the tide moved up the beach pushing us closer and closer to the dunes. By 3 p.m. we were driving through breaking surf. I felt we’d accomplished our mission. We had counted 615 dead dolphins and had evidence of the tragedy as well as necropsy samples that might shed light on what had produced this catastrophe.

Back in Lima, Carlos began doing histopathology analysis. That will be followed by immunohistochemistry tests for morbillivirus followed by tests for immunoglobulin antigen reaction with samples from fresh carcasses. We will also run a test on brucella if possible.

The possible cause of the UME are, as of this writing, absolutely unknown.

The possible cause of the UME are, as of this writing, absolutely unknown. Some have suggested seismic testing by oil companies, but many experts disagree. Carlos has performed tests for damage to the periotic bones (inner ear) of the dolphins he has necropsied and found some evidence of damage. But it is extremely difficult to perform such tests in the field. Often damage occurs to the fragile bones in the necropsy process. Further there is no indication of damage to the skin of the dolphins, something that would occur with sufficient blast to cause damage to the periotic bones.

Since there was no visible damage to the stranded dolphins, fisheries interactions, which have caused the deaths of millions of dolphins in the eastern tropical Pacific tuna fishery, can probably be ruled out.

Another candidate for the UME would be morbilla or other virus. Dolphins all over the world are suffering from compromised immune systems due to accumulation of POPs. These chemicals bioaccumulate up the ocean food web and are especially concentrated in apex predators such as dolphins. Some of the best-known POPs are PCBs, DDT, and dioxins.

Dolphins with compromised immune systems are susceptible to diseases such as leptospirosis, brucellosis and distemper, according to Dr. Peter Ross of Canada’s Institute of Ocean Sciences and a world recognized expert on the impact of toxic chemicals on marine mammals.

Peru’s response has been slow and scattered. Deputy Environment Minister Gabriel Quijandria told The Associated Press that studies are incomplete but officials hope to complete their research on the likely causes soon. I should point out that no definitive finding was ever made on the UME along the east coast of the United States during the late 1980s.

Quijandria said that the carcasses of 877 dolphins and porpoises had been found between February and mid-April on the beaches of northern Peru. “The most probable hypothesis is the possibility of an infection with a virus,” he said. “There are scientific articles about the incidence of morbillivirus, a type of distemper, in cetaceans in Peru, and that can be ruled out or proven next week.”

He said officials don’t believe the dolphins’ deaths are related to seismic oil exploration work that has been carried out off northern Peru by an American energy company.

Another official in the ministry of production, which includes fisheries, said that Peru really doesn’t care about dolphins. It cares about fish. And dolphins eat a lot of fish.

Another official in the ministry of production, which includes fisheries, said that Peru really doesn’t care about dolphins. It cares about fish. And dolphins eat a lot of fish. But he’s missing the point. The death of so many dolphins is telling us something dreadful about the oceans and possibly abouut the fish that the dolphins prey upon.

While the UME in Peru appears to be one of the worst ever for dolphins, it is not unique. In my book, The Voice of the Dolphins, I describe the die-off of hundreds of bottlenose dolphins along the East Coast of the United States in the late 1980s. No definitive conclusion was reached on what caused that tragic event but the multidisciplinary study group was brought together to issue findings concluded, “The results for the beach-cast specimens (dead dolphins) obviously reflect the levels of contaminants in the nearshore environment where the dolphins accumulate these substances.”

Another major UME involving morbillivirus killed several thousand striped dolphins along the Spanish Mediterranean coast from 1990 to 1992, followed by another in 2007. And significant die-offs of bottlenose dolphins have occurred along the coasts of Texas and Florida in the Gulf of Mexico, though nothing of the magnitude of the 1987-1988 UME along the East Coast. Another catastrophic event occurred in the North Sea during the late 1980s. Some twenty thousand seals, perhaps half of all Europe’s population of these animals, died from Phocine distemper.

Given the paltry resources available to investigate the die-off of dolphins along the Peruvian coast there is a strong possibility that the cause of the event may never be known. What is known is that catastrophic die-offs of dolphins and other marine mammals are occurring with greater frequency and virulence around the world. They are an indication that the oceans are in deep, deep trouble; perhaps greater trouble than we have imagined.

The Peruvian dolphin UME must be investigated thoroughly by independent international experts.

 

Hardy Jones is executive director of BlueVoice.org, author of The Voice of the Dolphins and producer of more than 70 films on the oceans, including Ocean Acrobats: The Spinner Dolphins. BlueVoice.org is an ocean conservation organization founded in 2000 by Hardy Jones and Ted Danson. Its mission is to protect dolphins, save the whales, and other marine mammals and to raise popular awareness about toxic chemicals in the oceans. BlueVoice has fought to end the slaughter of dolphins in Japan and to expose the harmful levels of toxins in the marine environment, including mercury, PCBs, and persistent organic pollutants, and their impact on both marine mammals and humans.