Hunting, Fishing Cause Dramatic Decline in Amazon River Dolphins
By Claire Asher
Populations of two species of river dolphin in the Amazon are halving every decade, according to the results of a twenty-two year survey.
The Amazon rainforest is home to the Amazon river dolphin, or Boto (Inia geoffrensis) and the Tucuxi (Sotalia fluviatilis). But the results of a long-term study published in PLoS ONE show that both of these once abundant aquatic mammals are now in rapid decline in the Brazilian Amazon, likely due to hunting and fishing.
Vera da Silva from the Instituto Nacional de Pesquisas da Amazônia, in Manaus, Brazil, and colleagues conducted monthly surveys of river dolphins in the Mamirauá Reserve in Amazonas state between 1994 and 2017. They found steep declines in both species over the last two decades, with Boto populations halving every ten years and Tucuxi every nine years—some of the most severe declines seen in cetaceans since the moratorium on commercial whaling came into effect in the 1980s.
"Data from over 22 years of monitoring … revealed a precipitous decline of [Boto] in the last two decades," said da Silva. "Before 2000, the population was quite stable."
Boto Amazon river dolphins (Inia geoffrensis). According to researchers, Boto populations are halving every ten years in the study area. Image courtesy of Associação Amigos do Peixe-Boi (AMPA)
The IUCN Red List categorizes both species as "data deficient," meaning that there is insufficient information to determine their conservation status; the murky waters of the Amazon river make them difficult to study. But the authors say that applying the IUCN Red List Criteria to their data would result in the species being listed as Critically Endangered, having suffered greater than 90 percent declines since 2000 (the Boto declined by 94 percent, and the Tucuxi by 97 percent in the study area, according to the researchers).
"In my opinion, the real importance of this paper is it shows that populations in their study site have a negative growth trend, and [the research] does it with quantitative information," said Elizabeth Campbell, a conservation scientist at ProDelphinus Peru, a conservation NGO based in Lima, Peru who was not involved in the current research. Although other studies have attempted to estimate population trends for these enigmatic creatures, "this is the only study that has had a constant presence for 20+ years, through different seasons, in [the same] area," she said.
Finding these illusive creatures requires patience and an eagle eye: "The Botos and Tucuxis come to the surface to breathe every 1-2 min," explained da Silva, which provides a brief window of opportunity to spot the creatures, before they disappear back into the muddy waters.
The scientist said that when they first began their surveys, the dolphins were plentiful. "When we started our work with these dolphin populations in 1994, we were astonished by the number of animals in the area," da Silva said. "It was impossible to go out by boat without seeing dolphins."
A Boto surfaces in the Marañón River, Peru. Difficult to detect in Amazonia's murky waters, both species are listed as "Data Deficient" by the IUCN. But researchers maintain that if region-wide surveys were conducted both species would end up being listed as Critically Endangered. Clara Ortiz-Alvarez
Over the years, the team not only counted the numbers of dolphins, it also captured and marked some, allowing the researchers to identify individuals in the field. As time passed, they started noticing huge scars from harpoon and machete injuries on the river dolphins they caught. Interviewing local fishermen confirmed the team's suspicions: "Botos were being hunted for bait, and in large numbers," said da Silva.
Around the turn of the millenium, catches of commercially important catfish known as Piracatinga or Mota (Calophysus macropterus) in Colombia were shrinking, so new fisheries began to spring up in Brazil to meet market demand.
By 2011, subsistence fishermen had shifted toward becoming commercial fishermen in the Brazilian state of Amazonas, as they hauled in 4.4 million kilograms (9.7 million pounds) of catfish each year. Part of their success could have been due to the bait they used. "They started using caiman meat," said da Silva, but soon found that Boto carcasses from entanglement with fishing gear were a more effective bait. "Dolphin meat lasted longer and [the catfish] preferred Boto carcasses," she said.
The supply of accidentally-killed Botos was soon exceeded by demand, and the fishermen started actively hunting them.
River dolphin leaping. Amazon river dolphins had been considered resilient compared to their Asian relatives. But this latest study shows that South America's river dolphins may also be headed toward oblivion unless action is taken to reduce hunting, fishing and other pressures on both species.F. da Silva VM
The dolphins were abundant at the time, and their high densities in small river inlets and bays, combined with their natural curiosity, made them easy targets, da Silva explained. The Brazilian government placed a five-year moratorium on fishing for piracatinga in 2014, but the practice still continues illegally.
Botos are found throughout both the Amazon and Orinoco river basins. In the wet season, the dolphins leave river channels and swim out into the flooded forests to search for prey among the roots and trunks of partially submerged trees.
Although legally protected in the Amazon, poor enforcement has meant that the species is still routinely entangled in fishermen's nets and gear, as well as deliberately hunted for fat and blubber. Some fishermen see the dolphins as a nuisance—competing with them for fish and damaging their equipment—and so kill them intentionally. "Fisherman do not like Botos because they damage the fish and the fishing gear," said da Silva.
In contrast to Boto, the survey showed that Tucuxi have been declining consistently since at least the mid-1990s. Unlike the Botos, Tucuxi don't enter the flooded forests to feed, but instead stick to the main river channels and tributaries. The species is smaller and faster-moving than the Boto, and is generally considered friendly and not a pest by local fishermen, making it less vulnerable to deliberate hunting. However, gear entanglement remains a serious threat, particularly because fishing nets are often set at the mouths of river channels where the Tucuxi tend to congregate.
Boto swimming in the Rio Amazonas, Brazil in 2016. A lack of political will, drastic cuts to the Brazilian environmental ministry budget, and continued illegal dolphin hunting and fishing are putting these aquatic mammals at risk.Martha de Jong-Lantink on Visualhunt.com / CC BY-NC-ND
The decline of both species is significant for aquatic ecology. River dolphins are a key part of the Amazonian ecosystem—Botos are known to feed on 43 different species of fish, most of which live near the river bottom, while Tucuxis feed on at least 28 species, mostly small schooling fish found higher in the water column. Many of these fish are commercially exploited, too, putting the dolphins in direct competition with local fishermen.
"The takeaway message for me is that fisheries interaction with river dolphins is probably the most significant threat these species face," said Campbell, adding that "populations are decreasing faster than we could expect."
Mamirauá Sustainable Development Reserve, where the study was conducted, is a 4,300 square-mile (11,000 square-kilometer) protected area—one of the largest in the Brazilian Amazon. Within the reserve, where commercial fishing is banned, mortality of dolphins is primarily the result of accidental deaths from subsistence fishing. However, some Botos travel up to hundreds of kilometers, straying outside the reserve where they may encounter other threats, including direct hunting, commercial fishing gear and pollution from agricultural run-off and mining.
One danger: toxic mercury, often used in mining to separate gold from soil and rock, accumulates in river sediments and can cause problems for top predators, like river dolphins, that consume large quantities of pollutants in the fish they prey on. The mercury bio-accumulates in increasing, eventually deadly, amounts in the dolphins' fat.
Amazon river dolphins had been considered resilient compared to their Asian relatives, the endangered Ganges river dolphin (Platanista gangetica) and the critically endangered Baiji (Lipotes vexillifer), which many conservationists believe may be extinct in the wild. Da Silva and colleagues' latest study shows that South America's river dolphins may also be headed toward oblivion.
Tucuxi swimming. Brazil's struggling economy means that fishermen are likely to try to increase their catches, even if that means illegally using dolphins for bait, or killing them either by accident or intentionally.Mike LaB on Visualhunt / CC BY-NC-ND
If Amazon basin dolphins are to survive, the Brazilian government needs to take the first step of strengthening existing protections and improving enforcement, da Silva said. "Controlling the fisheries catching catfish and preventing fishermen setting nets at the entrances of rivers, lakes and channels," would be a good start, she said.
Implementing dolphin protections and preventing illegal hunting in the flooded forests of the Amazon would be challenging, but is possible, da Silva said. But Brazil's environment ministry has seen draconian budget cuts (51 percent in 2017 alone) under the Temer administration, so it lacks the staff, equipment and fuel needed to monitor remote Amazonian regions. And as in many countries, there is currently a lack of political will to pass and enforce strong environmental legislation. Meanwhile, Brazil's struggling economy means that fishermen are likely to try to increase their catches, even if that means illegally using dolphins for bait, or killing them either by accident or intentionally.
"Fisheries in the Brazilian Amazon are not well controlled and quantified," da Silva said. And there is no sign that that reality will change soon.
Reposted with permission from our media associate Mongabay.
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By Michael Svoboda, Ph.D.
Despite a journey to this moment even more treacherous than expected, Americans now have a fresh opportunity to act, decisively, on climate change.
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EcoWatch Daily Newsletter
By Katy Neusteter
The Biden-Harris transition team identified COVID-19, economic recovery, racial equity and climate change as its top priorities. Rivers are the through-line linking all of them. The fact is, healthy rivers can no longer be separated into the "nice-to-have" column of environmental progress. Rivers and streams provide more than 60 percent of our drinking water — and a clear path toward public health, a strong economy, a more just society and greater resilience to the impacts of the climate crisis.
Public Health<img lazy-loadable="true" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTUyNDY3MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MDkxMTkwNn0.pyP14Bg1WvcUvF_xUGgYVu8PS7Lu49Huzc3PXGvATi4/img.jpg?width=980" id="8e577" class="rm-shortcode" data-rm-shortcode-id="1efb3445f5c445e47d5937a72343c012" data-rm-shortcode-name="rebelmouse-image" data-width="3000" data-height="2302" />
Wild and Scenic Merced River, California. Bob Wick / BLM<p>Let's begin with COVID-19. More than <a href="https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html?name=styln-coronavirus&region=TOP_BANNER&block=storyline_menu_recirc&action=click&pgtype=LegacyCollection&impression_id=2f508610-2a87-11eb-8622-4f6c038cbd1d&variant=1_Show" target="_blank">16 million Americans</a> have contracted the coronavirus and, tragically,<a href="https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html?name=styln-coronavirus&region=TOP_BANNER&block=storyline_menu_recirc&action=click&pgtype=LegacyCollection&impression_id=2f508610-2a87-11eb-8622-4f6c038cbd1d&variant=1_Show" target="_blank"> more than</a> <a href="https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html?name=styln-coronavirus&region=TOP_BANNER&block=storyline_menu_recirc&action=click&pgtype=LegacyCollection&impression_id=2f508610-2a87-11eb-8622-4f6c038cbd1d&variant=1_Show" target="_blank">300,000 have died</a> due to the pandemic. While health officials encourage hand-washing to contain the pandemic, at least <a href="https://closethewatergap.org/" target="_blank">2 million Americans</a> are currently living without running water, indoor plumbing or wastewater treatment. Meanwhile, <a href="https://www.theguardian.com/us-news/2020/jun/23/millions-of-americans-cant-afford-water-bills-rise" target="_blank">aging water infrastructure is growing increasingly costly for utilities to maintain</a>. That cost is passed along to consumers. The upshot? <a href="https://research.msu.edu/affordable-water-in-us-reaching-a-crisis/" target="_blank">More than 13 million</a> U.S. households regularly face unaffordable water bills — and, thus, the threat of water shutoffs. Without basic access to clean water, families and entire communities are at a higher risk of <a href="https://www.americanprogress.org/issues/green/news/2020/08/05/488705/bridging-water-access-gap-covid-19-relief/" target="_blank">contracting</a> and spreading COVID-19.</p><p>We have a moral duty to ensure that everyone has access to clean water to help prevent the spread of the coronavirus. Last spring, <a href="https://nymag.com/intelligencer/2020/03/coronavirus-stimulus-bill-explained-bailouts-unemployment-benefits.html" target="_blank">Congress appropriated more than $4 trillion</a> to jumpstart the economy and bring millions of unemployed Americans back to work. Additional federal assistance — desperately needed — will present a historic opportunity to improve our crumbling infrastructure, which has been <a href="https://www.theguardian.com/us-news/2020/jun/23/millions-of-americans-cant-afford-water-bills-rise" target="_blank" rel="noopener noreferrer">grossly underfunded for decades</a>.</p><p>A report by my organization, American Rivers, suggests that <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/07/09223525/ECONOMIC-ENGINES-Report-2020.pdf" target="_blank" rel="noopener noreferrer">Congress must invest at least $50 billion</a> "to address the urgent water infrastructure needs associated with COVID-19," including the rising cost of water. This initial boost would allow for the replacement and maintenance of sewers, stormwater infrastructure and water supply facilities.</p>
Economic Recovery<p>Investing in water infrastructure and healthy rivers also creates jobs. Consider, for example, that <a href="https://tinyurl.com/y9p6sgnk" target="_blank">every $1 million spent on water infrastructure in the United States generates more than 15 jobs</a> throughout the economy, according to a report by the Value of Water Campaign. Similarly, <a href="https://tinyurl.com/yyvd2ksp" target="_blank">every "$1 million invested in forest and watershed restoration contracting will generate between 15.7 and 23.8 jobs,</a> depending on the work type," states a working paper released by the Ecosystem Workforce Program, University of Oregon. Healthy rivers also spur tourism and recreation, which many communities rely on for their livelihoods. According to the findings by the Outdoor Industry Association, which have been shared in our report, "Americans participating in watersports and fishing spend over <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/06/30222425/Exec-summary-ECONOMIC-ENGINES-Report-June-30-2020.pdf" target="_blank">$174 billion</a> on gear and trip related expenses. And, the outdoor watersports and fishing economy supports over <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/06/30222425/Exec-summary-ECONOMIC-ENGINES-Report-June-30-2020.pdf" target="_blank">1.5 million jobs nationwide</a>."</p><p>After the 2008 financial crisis, Congress invested in infrastructure to put Americans back to work. The American Recovery and Reinvestment Act <a href="https://thehill.com/blogs/congress-blog/economy-a-budget/25941-clean-water-green-infrastructure-get-major-boost" target="_blank">of 2009 (ARRA) allocated $6 billion</a> for clean water and drinking water infrastructure to decrease unemployment and boost the economy. More specifically, <a href="https://www.conservationnw.org/news-updates/us-reps-push-for-millions-of-restoration-and-resilience-jobs/" target="_blank" rel="noopener noreferrer">an analysis of ARRA</a> "showed conservation investments generated 15 to 33 jobs per million dollars," and more than doubled the rate of return, according to a letter written in May 2020 by 79 members of Congress, seeking greater funding for restoration and resilience jobs.</p><p>Today, when considering how to create work for the <a href="https://www.bls.gov/news.release/pdf/empsit.pdf" target="_blank" rel="noopener noreferrer">10.7 million</a> people who are currently unemployed, Congress should review previous stimulus investments and build on their successes by embracing major investments in water infrastructure and watershed restoration.</p>
Racial Justice<p>American Rivers also recommends that Congress dedicate <a href="https://s3.amazonaws.com/american-rivers-website/wp-content/uploads/2020/07/09223525/ECONOMIC-ENGINES-Report-2020.pdf" target="_blank" rel="noopener noreferrer">$500 billion for rivers and clean water over the next 10 years</a> — not just for the benefit of our environment and economy, but also to begin to address the United States' history of deeply entrenched racial injustice.</p><p>The <a href="https://www.epa.gov/npdes/sanitary-sewer-overflows-ssos" target="_blank" rel="noopener noreferrer">23,000-75,000 sewer overflows</a> that occur each year release up to <a href="https://www.americanrivers.org/2020/05/fighting-for-rivers-means-fighting-for-justice/#:~:text=There%20are%20also%2023%2C000%20to%2075%2C000%20sanitary%20sewer,to%20do%20with%20the%20mission%20of%20American%20Rivers." target="_blank" rel="noopener noreferrer">10 billion gallons of toxic sewage</a> <em>every day</em> into rivers and streams. This disproportionately impacts communities of color, because, for generations, Black, Indigenous, Latinx and other people of color have been <a href="https://www.scientificamerican.com/article/flooding-disproportionately-harms-black-neighborhoods/" target="_blank" rel="noopener noreferrer">relegated</a> to live in flood-prone areas and in neighborhoods that have been intentionally burdened with a lack of development that degrades people's health and quality of life. In some communities of color, incessant flooding due to stormwater surges or <a href="https://www.ajc.com/opinion/opinion-partnering-to-better-manage-our-water/7WQ6SEAQP5E4LGQCEYY5DO334Y/" target="_blank" rel="noopener noreferrer">combined sewer overflows</a> has gone unmitigated for decades.</p><p>We have historically treated people as separate from rivers and water. We can't do that anymore. Every voice — particularly those of people most directly impacted — must have a loudspeaker and be included in decision-making at the highest levels.</p><p>Accordingly, the new administration must diligently invest in projects at the community level that will improve lives in our country's most marginalized communities. We also must go further to ensure that local leaders have a seat at the decision-making table. To this end, the Biden-Harris administration should restore <a href="https://www.epa.gov/cwa-401#:~:text=Section%20401%20Certification%20The%20Clean%20Water%20Act%20%28CWA%29,the%20United%20States.%20Learn%20more%20about%20401%20certification." target="_blank">Section 401 of the Clean Water Act</a>, which was undermined by the <a href="https://earthjustice.org/news/press/2020/tribes-and-environmental-groups-sue-trump-administration-to-preserve-clean-water-protections#:~:text=Under%20Section%20401%20of%20the%20Clean%20Water%20Act%2C,seeks%20to%20undermine%20that%20authority%20in%20several%20ways%3A" target="_blank">Trump administration's 2020 regulatory changes</a>. This provision gives states and tribes the authority to decide whether major development projects, such as hydropower and oil and gas projects, move forward.</p>
Climate Resilience<p>Of course, the menacing shadow looming over it all? Climate change. <a href="https://media.ifrc.org/ifrc/wp-content/uploads/2020/11/IFRC_wdr2020/IFRC_WDR_ExecutiveSummary_EN_Web.pdf" target="_blank">More than 100 climate-related catastrophes</a> have pummeled the Earth since the pandemic was declared last spring, including the blitzkrieg of megafires, superstorms and heat waves witnessed during the summer of 2020, directly impacting the lives of more than <a href="https://media.ifrc.org/ifrc/wp-content/uploads/2020/11/IFRC_wdr2020/IFRC_WDR_ExecutiveSummary_EN_Web.pdf" target="_blank">50 million people globally</a>.</p><p>Water and climate scientist Brad Udall often says, "<a href="https://www.youtube.com/watch?v=xQhpj5G0dME" target="_blank">Climate change is water change</a>." In other words, the most obvious and dire impacts of climate change are evidenced in profound changes to our rivers and water resources. You've likely seen it where you live: Floods are more damaging and frequent. Droughts are deeper and longer. Uncertainty is destabilizing industry and lives.</p><p>By galvanizing action for healthy rivers and managing our water resources more effectively, we can insure future generations against the consequences of climate change. First, we must safeguard rivers that are still healthy and free-flowing. Second, we must protect land and property against the ravages of flooding. And finally, we must promote policies and practical solutions that take the science of climate disruption into account when planning for increased flooding, water shortage and habitat disruption.</p><p>Imagine all that rivers do for us. Most of our towns and cities have a river running through them or flowing nearby. Rivers provide clean drinking water, irrigate crops that provide our food, power our homes and businesses, provide wildlife habitat, and are the lifeblood of the places where we enjoy and explore nature, and where we play and nourish our spirits. Healthy watersheds help <a href="https://news.un.org/en/story/2020/03/1059952" target="_blank" rel="noopener noreferrer">mitigate</a> climate change, absorbing and reducing the amount of carbon in the atmosphere. Healthy rivers and floodplains help communities adapt and build resilience in the face of climate change by improving flood protection and providing water supply and quality benefits. Rivers are the cornerstones of healthy, strong communities.</p><p>The more than <a href="https://archive.epa.gov/water/archive/web/html/index-17.html" target="_blank" rel="noopener noreferrer">3 million miles</a> of rivers and streams running across our country are a source of great strength and opportunity. When we invest in healthy rivers and clean water, we can improve our lives. When we invest in rivers, we create jobs and strengthen our economy. When we invest in rivers, we invest in our shared future.</p>
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