Conservation News: Vaquita, Jaguar, and White-Tailed Eagle

Vaquita Population Drastically Declined By ~40%

The vaquita porpoise found only in Mexico’s Gulf of California is the world’s most endangered marine mammal. Smallest of the seven species of porpoises, the vaquita may become extinct by 2022 if harmful fishing practices continue.

vaquita-population-and-abundance_13-may-2016-002International Committee for the Recovery of the Vaquita (CIRVA) estimated that the population is at around 60 individuals. A sharp decline from 2014 estimated population count of 97 vaquitas and a decline of more than 92% since 1997 when there were 570. This information was released by the based on 2015 surveys by an international team of scientists supported by the Mexican government.

The main threat to the survival of this little porpoise is bycatch by gillnet fishing. Gillnets are the primary fishing method to catch shrimp and fishes like the totoaba. During the shrimping season, about 435 miles of gillnets were set within the vaquita distribution every day. And by 2014, CIRVA estimated that half of the population had been killed in gillnets, leaving 97 alive.

In March of 2015, the Mexican government imposed a two-year ban on the use of gillnets and  pledged to invest $36 million each year to support affected fishing communities. The Mexican Navy was also sent to patrol the area to clear any nets found. But, despite President Peña Nieto’s commitment, totoaba fishing increased. Though the number of people jailed for illegal fishing and seizures of totoaba nets grew, efforts to implement more vaquita-safe fishing techniques failed.

Totoaba, an endangered fish species also endemic to the Gulf, is heavily hunted in Mexico for its swim bladders. Considered to be an expensive traditional Chinese delicacy, the bladders can sell for thousands of US dollars in China. They are often smuggled over the US border and then shipped to China. Its demand is driving the vaquita to extinction.

In the past four months, the enforcement team of the Navy and Sea Shepherd’s Operation Milagro removed forty-two illegal nets. However, three dead vaquitas were found in March, dying from entanglement in gillnets.

“The lure of big money for totoaba swim bladders killed at least three more vaquitas. Individuals [that are] sorely needed to prevent the species’ slide toward extinction,” said Frances Gulland of the Marine Mammal Center, who performed necropsies on two of the carcasses.

gillnet-exclusion-area_cirva-5

CIRVA stresses that the gillnet ban must become permanent if the species is to survive and recover. Other options include examining the feasibility of live capture and create a temporary safe haven but should not be an alternative to a permanent enforced ban.

Many conservationists are also in support of the ban.

World Wildlife Fund-Mexico CEO Omar Vidal said, “The vaquita can only be saved if the Mexican government immediately bans all fishing within its habitat.” He argued that a more stringent fishing and widespread fishing ban, more support for vaquita-safe fishing gear, and cooperation among Mexico, United States, and China to crack down on totoaba poaching must occur.

Barbara Taylor, a conservation biologist at NOAA’s Southwest Fisheries Science Center, agreed that the vaquita population could recover with proper government intervention and enforcement.

Gillnets also kill hundreds of thousands of porpoises, whales, dolphins and seals worldwide every year.  “If Mexico managed to solve this problem of vaquita mortality in gillnets, it would set an example for other nations, showing that fishermen can fish sustainably and co-exist with porpoises, dolphins, and other sea mammals,” says Taylor.

The Plight of the Vaquita Porpoise

Population of world’s most endangered marine mammal drops 40 percent

Facing Unrelenting Pressure from Deadly Nets, Mexico’s Vaquita Porpoise ‘Circles the Drain’

Stronger protection needed to prevent imminent extinction of Mexican porpoise vaquita, new survey finds

Vaquita, the World’s Most Endangered Marine Mammal

World’s Smallest Porpoise Is on the Verge of Extinction

 

Columbian Jaguars Adapting to Human Developments

A new paper from Panthera, the global wild cat conservation organization, and the Durrell Institute of Conservation and Ecology, was published in the scientific open-access journal PLOS One. Titled “Jaguar Densities Across Human-Dominated Landscapes in Colombia: the Contribution of Unprotected Areas to Long Term Conservation”, it was the first to provide jaguar density estimates in Colombia outside of the Amazon. Due to its position between Central and South America, Colombia is extremely important for range-wide jaguar conservation and research.

The researchers behind the study were Valeria Boron, an Italian PhD student from the University of Kent, and Dr. Esteban Payán, Colombia’s leading jaguar conservationist and Panthera Colombia director. Their team spent months placing camera traps across 150 square kilometers of previously uncharted territory in the savannas and cattle ranches of the Ilanos and in the Magdalena rainforests to study jaguar densities. The study estimated that there were three cats in 100 square kilometers.

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Cattle ranch in in the Municipality of Puerto Wilches, Santander, Colombia. © Valeria Boron

Valeria Boron noted, “Obtaining reliable and comparable density estimates is key to monitoring wildlife populations across space and time. For the first time in Colombia, we have the data to accurately detect jaguar population declines, estimate threats, and implement the appropriate conservation interventions before it is too late.”

The results show that jaguars can survive in presence of livestock, sustainable agriculture, and development, only if in a mixed landscape with wetlands and native lowland forests.

Dr. Payán stated, “Our results at both sites show that productive areas with extensive cattle ranching and oil palm cultivation display lower jaguar densities than natural areas such as the Belizean jungles and Brazilian Pantanal. However, they can still have resident jaguar populations.”

The jaguar (Panthera onca) is the largest felid species in the Americas with a range from Mexico to Argentina. However, it has disappeared from 54% of its historic range. The International Union for Conservation of Nature (IUCN) listed the jaguar as “near threatened” due to habitat loss and retaliatory killing following predation of livestocks, though the trade in jaguar skin declined drastically after the mid-1970s.

Jaguars’ large area requirements, low densities, and slow population growth rates leave them particularly vulnerable to habitat loss. Forests are turning into land to raise cattle or to grow crops like palm oil, soy, and sugar cane. The presence of cattle can cause the jaguars to come in conflict with the ranchers.

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Panthera

For long-term jaguar conservation, it is important to engage landowners, implement land-use plans to maintain natural habitats, and establish further oil plantations in already disturbed areas instead of destroying more habitats. Across cattle ranching regions, it is crucial to adopt optimal livestock management practices to lower the risk of human-jaguar conflict and jaguar killing.

“In large cat conservation, we want to achieve coexistence between wild cats and local people,” added Boron.

In order to successfully achieve each of these, it was important to obtain information on jaguar population and density estimates across human use/agricultural areas. The data will be used to properly “maintain a hospitable environment for jaguars in the surrounding unprotected areas and create seamless links between these private lands and protected parks across jaguar range,” says Dr. Payán.

The study highlighted the importance of engaging with local communities to improve relations. For the last eight years, the researchers have been working with the ranchers to find strategies on cow management to reduce conflict.

“Once you get the ranchers on your side they are great allies for the conservation of jaguars,” notes Payán.

Furthermore, they found that there were benefits to planting palm oil crops instead of rice or soy because they provide some cover for medium-sized carnivores that jaguars prey on.

“If you manage landscapes well, you can keep some of the biodiversity. By creating a mix of habitats you can encourage corridors to appear between protected areas, which will allow jaguars to cross from one to another.”  

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World Wildlife Fund

Preserving the jaguars, as the top predator, indicates a healthy ecosystem.

Dr. George Schaller, Vice President of Panthera and a co-author of the study, noted, “Jaguars are a species of conservation concern because they are suffering population declines and are keystone species in their ecosystems. Their presence ensures that their associated biodiversity is being conserved.”

Jaguar Densities across Human-Dominated Landscapes in Colombia: The Contribution of Unprotected Areas to Long Term Conservation

Colombian jaguars can coexist with humans according to a new study

Groundbreaking Jaguar Density Study in Colombia’s Unprotected Areas Highlights Possibilities for Long Term Conservation of the Species

 

Saving One Species May Be Hurting Another?

The white-tailed eagle, northern Europe’s largest bird of prey, is a conservation icon in Europe and was once recovering from near-extinction in the 1980s. The eagles finally bounced back after European countries banned the pesticide DDT and industrial chemicals known as PCBs. These pollutants dry out eggshells and affect embryo production, cutting the birds’ reproductive success by 80%.

Now, it has made an astonishing comeback with around an estimate of 24,500 mature individuals and is listed as ‘of least concern’ by IUCN.

However, its number and expected increasing growth rate may be posing a threat to other at-risk bird species. These apex predators require around a pound or half a kilogram of good per day, and as birds of prey, their diet includes other birds. This leads to a conundrum for conservationists.

“Ornithologists are trying to weigh conservation value of one species to another,” says Niklas Liljeback from Swedish Association for Hunting and Wildlife Management.

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White-tailed eagles battle it out in Poland. Photo: Willi Rolfes/Alamy

One of the white-tailed eagle’s choice of prey is the common eider and several experts believe that “the eagle a real threat to eider populations.” IUCN, in 2012, listed the common eider as ‘of least concern’; in 2016, it was uplisted to ‘near threatened’.

Markus Ost, an ecologist at Finland’s Abo Academy University that studies the eider, and his colleagues’ studies support a link between the white-tailed eagle boom and declining eider populations in the Baltic. According to the Baltic Marine Environment Protection Commission in Helsinki, Finland, the Baltic Sea coastline is home to well over 2,000 eagles whereas nesting eider females have declined from 7,000 to 1,000.

“We have been able to show that increased mortality of incubating female eiders is the strongest contributor to the population decline,” Markus Öst says. He adds that the rising losses due to predation are “most likely due to eagles”.

Since these nesting birds stay until it’s too late to escape in order protect their bests, they are an easy target for the white-tailed eagles.

“We have seen eagles both plunge diving from the air to catch females [or] systematically search for eider nests by hopping on the top of dense juniper [bushes] until the eiders try to get out of their nests,” he says.  

However, Bjorn Helander from Swedish Museum of Natural History disagrees. Instead of the eagle predation being a cause, it is just a symptom of the decline. Eiders feed on mollusks and changes in the food supply has forced the ducks “into the areas where more eagles are”. Helander continues with, “I’m not saying there’s not heavy predation on eiders, because there is. But it’s not the eagles that lie behind this big decline in the population. That’s simply ridiculous to me.”

eagle rangesAnother target the eagles prey on is the Baltic’s largest remaining colony of Caspian terns, listed by the country to be ‘near threatened’. On a tiny island north of Stockholm, the terns have been “plagued by eagles that pick the young ones one by one and eat them,” in the words of Ola Jennersten, a biologist at WWF Sweden.

In Sweden, the white-tailed eagles is preying on the lesser white-fronted goose, an endangered species with only a single breeding population in the Arjeplog. The government-backed Swedish Lesser White-Fronted Goose Project monitors their colony and regularly reinforces it with captive-bred birds. In 2012, the year that the white-tailed eagles appeared in the area, the goose population fell from 150 to 60 geese.

Though it is not known how many eagles prey on the geese, Liljebäck, who directs the project, notes that there is at least one individual specializes in targeting them during their summer molt.

He also says that the stress and disturbance caused by the eagle attacks have further impacts. One such effect is that the temporarily flightless geese are forced off the lakes that protect them from predators like foxes.

Scientists, including Rimgaudas Treinys, an avian ecologist of the Nature Research Center in Vilnius, Lithuania,  are also concerned that the eagle may be displacing the osprey, another protected bird of prey, in eastern Baltic countries. However, Helander argues that “When the sea eagle was exterminated from Sweden, ospreys took over all that habitat because they were fishermen, and now the eagle takes back its old grounds.” Simply, the white-tailed eagles’ historical range is being restored by nature.

Lastly, the black stork may also be on the eagle’s menu as evidenced by remote nest cameras and meal remains. Once a common species, it may be abandoning its nesting sites due to the growing presence of eagles.

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People in Norfolk, England, protested reintroductions of the white-tailed eagle with this sign. Photo: FLPA, ALAMY

Though solutions are being tested like using wooden shelters that protect nesting eiders, Öst and Treinys argue that the best solution would be to stop actively supporting the white-tailed eagle.

“Measures directly aimed at reducing eagle numbers are out of the question as being too controversial,” Öst says, and “would certainly provoke an outcry by nature-protection agencies and organizations alike.”

Jennersten believes that culling the individual eagles that target the vulnerable bird populations may be necessary.

Helander, however, says that “evidence for any drastic action against eagles is really very poor” and is opposed to any kind of eagle control.

In the words of Jennersten: “One way or another, nature will find a balance.”

IUCN: White-tailed Eagle

Small-scale spatial and temporal variation in the demographic processes underlying the large-scale decline of eiders in the Baltic Sea

Can There Be Too Many Eagles?

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