Showing posts with label Oceans. Show all posts
Showing posts with label Oceans. Show all posts

Tuesday, December 21, 2021

Long-distance movement of microplastics

Nature Communications

Microplastic pollution collected at a Key largo,
Florida beach State Park. An Ocean Blue Project photo.

Microplastics, detected in southern France, could have been transported over 4,500 km from their source, including over continents and oceans, suggests a study published in Nature Communications. The findings suggest that microplastic pollution can spread globally from its sources to remote regions.

Plastic pollution has been documented at high elevations and latitudes, and in regions with little local plastic use. The transportation of microplastics through the atmosphere has been suggested as occurring on regional scales. However, it is unclear how widespread this phenomenon is and, if like mercury and other pollutants, there is free transport of microplastics through the atmosphere that enables trans-continental movement.

Steve Allen and colleagues collected atmospheric microplastics at the high-elevation Pic du Midi Observatory in the French Pyrenees, southern France, and used atmospheric transport modelling to understand the potential sources and paths of these particles. Air masses containing microplastic' particles were found to have moved around 4,550 km on average in the week before arriving at the observatory, and were projected to mainly have arrived from the west and south, over the Atlantic Ocean and Mediterranean Sea. The authors suggest that the potential sources of the microplastics may include North America, western Europe and North Africa, indicating trans-continental and trans-oceanic transport through the free troposphere (the layer of atmosphere above the clouds).

The findings suggest that regions with little local plastic usage could be impacted by microplastic source regions located far away


Tuesday, November 9, 2021

Airguns and ship sounds dangerously disrupt the natural behaviour of the "unicorn of the sea." Study

The Royal Society - Biology Letters

A pod of narwhals in the Arctic.

Manmade noise is increasing in the Arctic, posing a threat to narwhals. To study this, narwhals were fitted with tags and exposed to ship and airgun noise. The whales showed clear reactions to sound disturbance by first reducing and then ceasing foraging. Reactions could be detected as far as 40 km from the ship, where the signals were embedded in the natural background noise. The reactions of the whales demonstrate their sensitivity and emphasize that - "if healthy narwhal populations are to be maintained," humans need to "manage" activities that make such noise.

The findings have just been published by the Royal Society.

Please also read:

RAPIDLY WARMING OCEANS HAVE LEFT MANY NORTHERN MARINE MAMMALS SWIMMING IN TROUBLED WATERS. BUT PERHAPS NONE MORE SO THAN THAT STRANGE AND MYSTERIOUS "UNICORN OF THE SEA," THE NARWHAL.


Wednesday, November 3, 2021

Baleens - beneficial gluttons of the high seas

Scientists believe the ravenous appetites of baleen whales - Earth's largest creatures - and their prodigious waste - hold clues to the very health and productivity of our oceans.

by Larry Powell

A blue whale (Balaenoptera musculus) defecates. Photo credit-Ryan Lavery (Smithsonian)

Baleens include humpbacks, fins, minkes and blue whales, the latter being the largest creatures ever to live on Earth. The carnivorous marine mammals catch and consume vast amounts of prey. And they recycle ocean nutrients by excreting undigested food in what have been described as "volcano-like" movements.

A minke whale tagged by the research team off the coast of Antarctica in 2019. Credit: Ari Friedlaender under NOAA/NMFS permit 23095.


By attaching tags to the backs of 321 whales from seven baleen species, the researchers now reckon that - before the onset of whaling in the twentieth century - and in the Southern Ocean alone - baleens were, amazingly, consuming more than twice what the world's entire marine fisheries catch today. 

A humpback whale feeds on sand lance in the Stellwagen Bank National Marine Sanctuary. Credit: Elliott Hazen


Yearly, they probably ate 430 million tonnes of Antarctic krill (small crustaceans found in all the world's oceans) before whaling ramped up in the 19 hundreds in the Atlantic, Pacific, and Southern Oceans. That's up to thirty percent of their entire body mass, on average, and, in some areas of the ocean at least, triple the volume previously thought. And, incredibly, it's twice the total biomass of this entire species of krill thought to exist today. 


The scientists hope, if baleen numbers could somehow recover to what they were before that twentieth century whaling, their "nutrient recycling services" could not only help boost ocean productivity but restore ecosystem functions to their previous glory.

According to the Smithsonian Institute, heavily involved in the study, whales both eat and excrete immense amounts of iron. It is an important nutrient which spurs the growth of phytoplankton blooms. If it weren't for the whales, this valuable commodity would sink from near the surface, where the whales live (and where the iron is needed), to the bottom where it would be lost. 

These findings have just been published in the journal, Nature.


Tuesday, September 14, 2021

Australian bushfires triggered prolific phytoplankton blooms vast distances away

Nature

Bushfire East of Lake Dundas, Western Australia. Photo by Pierre Markuse

The 2019–2020 Australian wildfires released more than twice as much CO2 as previously reported on the basis of different fire inventories, reports a Nature paper. 

An independent study also published in Nature, suggests that aerosol emissions from these wildfires are likely to have fuelled vast plankton blooms thousands of kilometres away in the Southern Ocean. 

The findings highlight the complex links between wildfires, ecosystems and the climate. Climate-change-driven droughts and warming play a role in increasing the frequency and intensity of wildfires, which release CO2 into the atmosphere, potentially driving further climate change and increasing the risk of wildfires. 

In the summer season of 2019–2020, around 74,000 km2 — an area roughly equivalent to 2.5 times the area of Belgium — burned in the eucalyptus forests in the coastal regions of Victoria and New South Wales, Australia. These wildfires are known to have been extremely large in scale and intensity, and to have released large amounts of CO2 into the atmosphere, but emission estimates remain uncertain.

To gain insights into the amount of CO2 released by the Australia wildfires, Ivar Van der Velde and colleagues analysed new high-resolution satellite measurements of carbon monoxide concentration in the atmosphere, from which they infer fire-induced carbon emissions. They estimated that around 715 teragrams of CO2 were emitted between November 2019 and January 2020 — more than twice the amount previously estimated from five different fire inventories and comparable to a bottom-up bootstrap analysis of this fire episode, surpassing Australia’s normal annual fire and fossil fuel emissions by 80%. 

Gaining a stronger understanding of the atmospheric burden of CO2 caused by these fires, and what they will cause in the future, is critical for constructing future scenarios of the global carbon balance, the authors note.

In addition to carbon emissions, wildfires release aerosols that affect ecosystems; for example, transportation of nutrients such as nitrogen and iron can enhance plankton growth. Nicolas Cassar, Weiyi Tang and colleagues report the presence of extensive phytoplankton blooms from December 2019 to March 2020 in the Southern Ocean, downwind of the fires. Aerosol samples originating from the fires contained high levels of iron, which the authors suggest were transported vast distances and fertilized the blooms.

Together, these studies demonstrate that wildfires can have an important influence on atmospheric CO2 levels and ocean ecosystems.


Sunday, May 30, 2021

A serious disease of Chinook salmon, originating from fish farms in Norway, has now spread to wild salmon off the coast of BC: Study.

University of British Columbia

The Chinook salmon. Photo by Zureks.

The virus known as PRV, is associated with kidney and liver damage in Chinook salmon.  A new study in Science Advances shows -- it's continually being transmitted between open-net salmon farms and wild juvenile Chinook salmon in British Columbia waters.

The study traces its origins to Atlantic salmon farms in Norway and finds that the virus is now almost ubiquitous in salmon farms in B.C.

It also shows that wild Chinook salmon are more likely to be infected with PRV the closer they are to salmon farms, which suggests farms transfer the virus to wild salmon.

Genome sequencing of viruses from farms and wild fish further indicates that transmission occurs between farms and wild salmon.

"Both our genomic and epidemiological methods independently came to the same conclusion, that salmon farms act as a source and amplifier of PRV transmission," said Dr. Gideon Mordecai, a viral ecologist and Liber Ero fellow with UBC Science and researcher with UBC Medicine, who led the study. "Because separate lines of independent evidence all point to the same answer, we're confident in our finding."

Sequencing of 86 PRV genomes helped researchers track the history of PRV emergence in British Columbia. They estimate that the lineage of PRV in the North East Pacific diverged from PRV in the Atlantic Ocean approximately 30 years ago. This suggests that the introduction of PRV to B.C. and infection of wild Pacific salmon is a relatively recent phenomenon, coincident with the growth of salmon aquaculture in the province -- not dating back to early attempts to introduce Atlantic salmon to the region, starting in 1874.

"There is much confusion about where PRV is originally from, whether it is transmitted between farmed and wild salmon, and how different lineages of the virus cause different severities of disease," said Dr. Mordecai. "This study's genome sequencing clearly indicates PRV is not native to B.C. waters -- it originated in the Atlantic Ocean and has been spread around the world through salmon aquaculture."

RELATED: "Toxic Tides."

The study highlights the role of aquaculture in introducing novel pathogens to new regions, where they then spread to wild fish, and integrates the expertise of the two senior authors, Dr. Kristi Miller, a DFO scientist and Professor Jeffrey Joy, a UBC evolutionary geneticist. It demonstrates the value of genomics in the surveillance of viral pathogens affecting important fisheries resources and how analytical methods derived from the epidemiology of human viruses can be adapted and applied to conserving wild salmon populations.

Further analysis of PRV genomes generated by the study suggested that there has been a growth in the number of PRV infections in B.C. over recent decades. This finding corresponds with the regional growth in salmon aquaculture and high rates of viral infection in salmon farms.

"Our finding that PRV is transmitted between farmed and wild salmon is particularly relevant given recent field and laboratory studies showing the lineage of PRV in B.C. is likely to cause disease in both Pacific and Atlantic salmon" says Dr. Mordecai. A recent Norwegian study found that a Canadian isolate of the virus causes heart lesions in Atlantic salmon. More importantly to the Pacific ecosystem, PRV has been associated with a different disease in Chinook salmon in which blood cells rupture, leading to kidney and liver damage. These are in contrast to the DFO's assessment that PRV is not a disease agent.

"Our study reaffirms that a more precautionary approach to managing salmon farming in BC is warranted," says study co-author Dr. Andrew Bateman, of the Pacific Salmon Foundation. "The PRV findings, in particular, support calls to transition from open-net salmon farming towards farming technology that doesn't allow disease transfer between farmed and wild salmon, protecting BC's wild Pacific salmon from serious risk in the process."

"The study provides foundational information necessary to assess the risk of salmon aquaculture on wild fish, as recommended by the Auditor General of Canada's 2018 Report on Salmon Farming, which criticized DFO's ability to manage aquaculture in a precautionary manner," says Professor Jeffrey Hutchings of Dalhousie University, a leading Canadian fisheries scientist who was not involved with the research. "The work by Mordecai, Miller, and colleagues on PRV provides the most compelling, scientifically objective evidence to date that wild salmon in BC are at increased risk of disease because of open net-pen Atlantic salmon aquaculture," adds Professor Hutchings.

 The collaborative study included UBC. and the Department of Fisheries and Oceans.



Tuesday, December 15, 2020

Tough Times for Animal Travellers

Committee on the Status of Endangered Wildlife in Canada. (COSEWIC)

The Blackmouth (Oncorhynchus tshawytscha) a type of Chinook. 

Image by Animal Diversity Web.

After maturing at sea, Chinook Salmon on Canada's West Coast swim back to their natal streams to spawn. Twenty-eight populations of Chinook Salmon live in Southern British Columbia, each with different habitats and survival strategies. Chinook Salmon face many threats in both fresh and saltwater, including climate change and detrimental effects from hatchery fish. At the current meeting, COSEWIC considered the 12 populations of Chinook Salmon most impacted by hatcheries: four were designated Endangered, three Threatened, and one Special Concern, while one was deemed Not at Risk. Three remote populations were determined to be Data Deficient, and will require additional research before being re-assessed. Details here.

Friday, November 27, 2020

As giant ice shelves collapse amid global warming in the Arctic, experts call for more protection for the "Last Ice Area" (LIA). The vast communities of plants and animals living there could be lost, they warn, before we even get to understand them!

    by Larry Powell 
                                The vast Milne Ice Shelf broke up this summer. Animals found 
living within its ice cavity (red box), are shown on the right. 
Photo credits: Left: Joseph Mascaro, Planet Labs Inc. 
Right: Water and Ice Laboratory, Carleton University.

Using tools which included video taken by a robot submarine, a Canadian research team recently discovered an amazing array of plants and animals, living in the heart of Milne, the very ice shelf which broke apart just this summer north of Ellesmere Island (above), losing almost half of its mass.

Dr. Derek Mueller, Professor of Geography and Environment Science at Ottawa's Carleton University, is a team member who's worked in the area for decades. In an email to PinP, he can barely disguise his excitement over what they found.

"There are really neat microbial mats (communities of micro-organisms including cyanobacteria, green algae, diatoms, heterotrophic bacteria, and viruses) that live on the surface of the ice shelves. Similar microbial mats can be found in ponds on the bottom of shallow lakes... Inside the sea ice and clinging to its underside are communities of algae and lots of kinds of phytoplankton in the ocean as well." 
Small animals from marine waters under the sea ice in Tuvaijuittuq, a Marine Protected Area in the region. Photo credit: P. Coupel and P. Tremblay, Fisheries and Oceans Canada.
So what might the world lose if these organisms disappear with the ice?

"This Last Ice Area will hopefully serve as a refuge for ice-dependent species," Dr. Mueller explains, "both on land and in the marine environment.  We know relatively little about these organisms - how they are adapted to their surroundings, how unique they are (or perhaps how similar they are to their cousins in analogous environments in the Antarctic) and many more questions!  We won't get to ask these questions if global temperatures rise unabated and this ice melts away."

The images above come from just a tiny part of the vastness Mueller refers to, called the "Last Ice Area." And, in the face of a rapidly-warming Arctic, events involving the break-up of sea ice are all too common there.
What's left of the Ward Hunt Ice Shelf in the Last Ice Area 
after breaking apart in 2011Credit: CEN, Laval University.

Here's how Dr. Mueller describes the LIA. 

"'The Last Ice Area' means the region in the Arctic Ocean where sea ice is most likely to survive in a warming world." 

It sprawls for up to 25 hundred kilometres along the coastlines of northern Canada and Greenland and well out to sea. It's there that the thickest sea-ice in the entire Arctic can be found. Because of its importance as a home for ice-dependant marine life and its cultural significance to the Inuit people living there, they and the World Wildlife Fund have long promoted it as worthy of conservation. (Local Inuit elders call it “Similijuaq - place of the big ice.”) 

Dr. Mueller and a colleague, Dr. Warwick Vincent of Laval University in Quebec City, are now sounding the latest alarm bells over why additional measures are needed to protect the area from increased human activity.

While Dr. Mueller remains optimistic for the future, he suggests, further steps need to be taken to expand those existing, protected areas. 

"The good news is, we do still have a window to make a difference. We can augment the existing conservation areas - the marine one, Tuvaijuittuq MPA and the terrestrial one - Quttinirpaaq National Park,  with more optimal coverage of the LIA - from Greenland in the east to the NWT in the west and perhaps there could be more protection by expanding across the coastal region reaching both inland and offshore." 

The Government of Canada announced the creation of Tuvaijuittuq Marine Protected Area a year ago, aimed at protecting a large part of the LIA.
 It's not just marine life that will be vulnerable to melting ice. So, too will terrestrial (land) animals 
such as the Peary caribou, known to migrate across the sea ice. 
Photo by Paul Gierszewski - Nunavut.


"This would recognize the important interconnection between the terrestrial and marine environments. With vulnerable ice-dependent ecosystems protected from human activity, this will guarantee the removal of multiple environmental stressors.  The big stressor is, of course, climate change. But, if we can make good on our Paris commitments to reduce greenhouse gas emissions globally, then the chances of the LIA remaining, increase dramatically."   

The team's findings were published recently in Science Magazine.

Tuesday, November 17, 2020

Recent research shows: More rare, endangered sharks are dying in the worldwide trade in shark fins than earlier feared.

by Larry Powell

  The "Grey Nurse" or "Sand Tiger," shark ( Carcharias taurus), a coastal species on the ICU's Red List as critically endangered. A public domain photo by Richard Ling. 



After hauling them aboard their vessels, the fishermen cut off their fins, then toss them back into the ocean. Still alive, they sink to the bottom where they're either eaten by other predators or die of suffocation. 
 
About 100 million sharks are believed to be taken by fishers each year, most of them for their fins alone. 

It's an industry estimated to be worth US$400 million a year. 
The blue shark (Prionaceglauca). Photo by Mark Conlin/NMFS.

If one were to believe official trade records over the past twenty years, most fins traded on world markets have come from more abundant "pelagic" species (ones which live in the open ocean) like the blue shark (above). 

The leopard shark (Stegostoma fasciatum). An ADV photo by Jeffrey N. Jeffords. 
Using advanced techniques in barcoding and genetic tracing, scientists are now painting a different picture. By analyzing more than five thousand fins from markets on three continents, they still found a lot had come for those "pelagic" populations. But they also found "an additional 40 'range-restricted' coastal species" which did not show up in previous records. These populations live closer to shore and do not range as widely as those in the open oceans. With local jurisdictions providing little protection for them, their populations now face "dramatic declines" and are "typically less abundant."  

However, even the more common deep-sea species have been falling victim to "chronic exploitation" by fishers who are "collapsing" their populations, too. 
New DNA tracking techniques are revealing a greater number of threatened and coastal sharks from stockpiles of intact shark and processed fins (pictured). Image credit: Paul Hilton.

So, if we want to conserve sharks and curb the "unsustainable global trade in shark fins," conclude the researchers, "stronger local controls of coastal fishing are urgently needed."

Their study was published this summer in the proceedings of The Royal Society.

But this is hardly the first cautionary tale pointing to the plight of Earth's marine life in general and sharks, in particular. Another research paper published in 2017 warns, they face "possibly the largest crisis of their 420 million year history. Many populations are overfished to the point where global catch peaked in 2003, and a quarter of species have an elevated risk of extinction."

RELATED:

Tuesday, September 8, 2020

Arctic ocean moorings shed light on winter sea ice loss

Science Daily
A table iceberg in the Norwegian Arctic. Such icebergs are rare
as they calve from shelf ice, which is also rare. They're normally
a typical form of iceberg in the Antarctic. This one is about 12m high
and about half the size of a soccer field. Photo by Andreas Weith.




















The eastern Arctic Ocean's winter ice grew less than half as much as normal during the past decade, due to the growing influence of heat from the ocean's interior, researchers have found. Story here.


Wednesday, August 19, 2020

There is at least 10 times more plastic in the Atlantic than previously thought

Science News 

"Seal trapped in plastic pollution" by tedxgp2 

Scientists measured 12-21 million tons of three of the most common types of plastic in the top 200 meters of the Atlantic. By assuming the concentration of plastic in the whole Atlantic is the same as that measured at 200 meters deep, the scientists estimated there is around 200 million tons of three of the most common types of plastic alone. Compare this to the previously estimated figure of 17 million. 

Details here.

Wednesday, August 5, 2020

Measuring ecosystem disruption caused by marine heatwaves

 Nature

Above, healthy bull kelp.
Below, bull kelp degraded by
a marine heatwave. DeWikiMan
Marine heatwaves can displace thermal habitats by tens to thousands of kilometres, reports a study in Nature this week. This displacement represents the distance that an organism would have to travel to escape potentially stressful temperatures. The findings open new avenues of research to understand the potential impacts of anomalously warm ocean temperatures on marine species.

Marine heatwaves are distinct periods of unusually warm ocean temperatures that can cause dramatic changes to ocean ecosystems, as inhabitants find themselves in waters that are warmer than they are accustomed to. Much of the research into these events focuses on the local impact to species such as corals, but does not take into account mobile organisms (fish, for example) that can travel to find their preferred conditions.

To understand how species may have to redistribute under marine heatwave conditions, Michael Jacox and colleagues analyse thermal displacements associated with marine heat waves using data from 1982 to 2019. They calculate the minimum distance that a species would have to travel away from a marine heatwave to reach a habitat at their preferred temperature. This displacement varied substantially: in the tropics, where temperature gradients are small, the thermal displacement could exceed 2,000 km; in regions with sharp gradients, such as western boundary currents, displacement might be only a few tens of kilometres.

The authors note that the short-term displacement of thermal habitats is comparable to shifts associated with long-term warming trends, and may have the potential to drive rapid redistributions of marine species.

Tuesday, June 30, 2020

Rapidly warming oceans have left many northern marine mammals swimming in troubled waters. But perhaps none more so than that strange and mysterious "unicorn of the sea," the narwhal.

by Larry Powell


Narwhals are cetaceans, a family of marine mammals which includes whales and dolphins. Most are found in Canada's Baffin Bay and Davis Strait, in the high Arctic and Atlantic Arctic. Others live off Greenland, Norway and Russia. Many spend several months over winter, beneath the ice-pack, feeding on fish, squid and shrimp and their summers in more open water. It's believed they're capable of diving as deep as 15 hundred meters and holding their breath for an astonishing 25 minutes! 
Narwhals breach through an opening in the ice-pack.                     Photo credit - US Fish & Wildlife.
A pod "breaches" through an opening in the sea-ice. 
A US Fish & Wildlife Service photo. 
They can weigh up to two thousand kilograms and reach a length of about five meters. They're much larger than some dolphin species, but tiny compared to the mighty blue whale. Many migrate along the ice's edge some 17 hundred kilometres from Canada to Russia.

The males grow long, spiral tusks - actually overgrown teeth - that can protrude up to three metres from their head. While they’re predators, narwhals are also preyed upon. Killer whales (orcas) are believed to be taking them increasingly as warming waters lure the orcas further north.

But man likely remains their prime enemy.

Indigenous hunters of Greenland and Canadian high Arctic - the Inuit - have, for centuries, depended on them as an important food source. Canada officially recognizes the right of the Inuit to hunt them. But they must adhere to a quota system. It's based on findings from periodic, scientific aerial surveys mandated by both Canada and Greenland, designed to protect narwhal populations from over-harvesting.

Recent numbers are hard to find. But one official survey in 2010 concluded that Inuit hunters took almost a thousand narwhals off Canada and Greenland that year.

So, just how intimately are narwhals tied to their world of ice and snow? 

"Narwhals are uniquely adapted to the extreme conditions of an Arctic existence," the study states, "and their evolution and ecology intrinsically tied to the past and present sea ice dynamics of the region." Narwhals are known to have lived through extreme climatic changes for thousands of years. Yet they're also thought to be among the most vulnerable to those changes of any of the northern marine mammals.

The researchers hoped, by studying their past, they could gain an insight into their future. What they found was concerning. Before and after the onset of the last ice age (LGM), more than 26 thousand years ago, both the number of narwhals and their genetic diversity were perilously low. But they "responded positively" to both the warming and expansion of habitat which occurred after it ended some 19 thousand years ago. Their numbers increased, and so did other marine predators like belugas and bowhead whales.

However, the benefits such animals enjoyed in that post-glacial period, may be coming to an end. "Many polar marine predators are being negatively affected by global warming, which is decreasing the availability of habitat and prey," the study finds. "Although the range and effective population size of narwhals increased post-LGM, their future in a rapidly changing Arctic is uncertain. Narwhal distribution will be further affected in the near future, as the species also faces increased human encroachment, changes in prey availability, new competitors and increased predation rate by killer whales."

Areas which were once inaccessible to people, due to ice and snow cover, are now receding. This is allowing more activities such as fishing, oil exploration and drilling. And narwhals are known to be easily disturbed, and to flee from areas they like to frequent in summer, like fiords, bays and inlets.

So, are their numbers crashing? 

The researchers admit, there's a good deal of uncertainty when it comes to population trends. World population estimates have ranged from 50 thousand to 170 thousand. As those estimates have wavered, so has their status on the endangered species list of the International Union for Conservation of Nature - from "nearly threatened" to "of least concern."

A veteran biologist with Fisheries and Oceans Canada, Dr. Steven Ferguson, has extensive experience observing marine mammals in the north. While he doesn't give hard numbers, he tells PinP, "Both the Baffin Bay and Northern Hudson Bay populations appear to be relatively constant and do not appear to be depleted."

However, the good news seems to end there.

"Populations off the eastern shores of Greenland," he goes on, "seem to be experiencing a decline. And two stocks off West Greenland, appear to be lower in abundance relative to the past."

So, will these wondrous "unicorns of the sea" continue to ply their ways through the world's northern oceans just as they have for so long in the past? Or are their numbers destined to dwindle to a dangerous few, like so many other of Earth's wild things?

Wednesday, January 22, 2020

Toxic Tides - The Tragedy of Fish Farming Everywhere

One of the biggest challenges facing the aquaculture industry everywhere, is Lepeophtheirus salmonis, the sea-louse (below).

It's a parasite which attacks both farmed and wild salmon, causing lesions and infections which stunt their growth. But the costs of de-lousing are high. And so are the losses suffered by the industry in the marketplace. Many lice can actually kill many fish.
Sea lice, Lepeophtheirus salmonis, on farmed
Atlantic salmon, New Brunswick, CA. Photo by 7Barrym0re 

To fight back, the fish-farmers dump pesticides into the waters (below). But, because they’re released directly into the environment, they not only kill the lice, but place beneficial, “non-target” organisms at risk, too. And several of these live in the open ocean, beyond the confines of the farms.
This image shows how industry applies pesticides within their operations.

The latest (but not the only) cautionary tale about the wisdom of this practise, has just emerged from Norway. 

A team of researchers there exposed (in the lab), an important food source for the fish, to varying levels of hydrogen peroxide (H202).  It's the active ingredient in several such products.
Calanus spp. Illustration by the Scripps Institution of Oceanography.

The  food source  was a zooplankten called Calanus spp. 

It's abundant in coastal waters where many salmon farms are located and is a key component in the North Atlantic food web. It's important, not only to young farmed fish, but to wild herring and cod, as well. 

The lab results were convincing.

In just one hour, at only 10% of levels the farmers would apply, 92% of the juvenile Calanus spp. and all of the adult females died. And, at much lower doses (1% or less), the ability of the organisms to take in oxygen was greatly reduced. Their “escape response” was destroyed, making the likelihood of them being eaten by predators, "extremely high." 

The researchers concluded, "Present recommended levels of application underestimate the impact of the pesticide on non-target crustaceans. 

I interviewed the lead author of the study, Rosa Escobar Lux of the Marine Austevoll Research Station, Norway.

PinP: Do you have any evidence that the abundance of Calanus spp. may be affected to the degree that the fish themselves are becoming "food-deprived?" 

Dr. Escobar Lux: "No. Our experiments were done in a laboratory which can answer some of our questions but it does not give definite answers to what is happening in the wild.  Also, there's a need for dispersion models to help us understand the real magnitude of the effects."

The findings of her team were published recently in the Canadian science journal, FACETS.

Is evidence of harm confined to the lab?

Another study from Norway published just last month, takes us beyond the lab, into open waters (or "the wild" as Dr. Escobar Lux puts it). It reveals, elevated levels of the pesticide diflubenzuron (DFB) are being found in commercially-valuable northern shrimp (Pandalus borealis) in Norwegian fjords. Salmon farms there use a medicated feed containing that product. Lab tests have shown it can be lethal to the shrimp, and actually becomes more toxic in warmer waters. This raises added concerns in a world that is heating up fast.

Many Norwegian fishers report, they're catching fewer shrimp in fjords where salmon farms are operating. Experts want further studies to find out if shrimp populations are already crashing. 

And yet another recent study reaches a similar conclusion, that 
hydrogen peroxide's toxicity may already be making itself felt in the open ocean, on northern shrimp. Conducted by mostly Norwegian researchers, they find hydrogen peroxide may be causing "gill damage and delayed mortality" to the shrimp, more than a kilometre from fish farms there.

Even older studies, some done in Canada, point to several other marine creatures being vulnerable to aquacultural pesticides, too. These not only include zooplankten like the kind already referred to, but commercially valuable catches such as lobster and shrimp!

Last year, experts "rounded up" those studies and combined them in  a single, "systematic and exhaustive" review. 

They concluded that hydrogen peroxide wasn't the only suspect product. Three others, cypermethrin, deltamethrin and azamethiphos - each used extensively in the industry - had similar effects. 

The review concludes, "Aquaculture has consequences for the environment. Salmon and trout cage culture has required the use of large quantities of pharmaceuticals. Our results show clear negative  effects at concentrations lower than those used in treatments against sea lice in all of the species studied." 

Despite all of this, in 2016, quite some time after much of this research was known, Health Canada granted "full registration for  the sale and use" of pesticides using hydrogen peroxide as their active ingredient" for the treatment of sea lice on Atlantic salmon reared in marine aquaculture sites." That was at least five years after the first warnings about the pesticides I was personally able to find…warnings that our government officials must have been aware of. 

A year later, the Department registered also azamethiphos for an identical use, giving identical reasons for doing so. 

In its documents approving registration of both products, Health Canada concludes, "Under the approved conditions of use, the products have value and do not present an unacceptable risk to human health or the environment.  <They are> relatively benign products that pose little or no risk to salmon, the marine environment, non-target species, or human health." 

It went on to recommend that the industry, facing one of its worst years for sea lice that year, be allowed one treatment more of H202 than was usually allowed. 

In addition to H202, Canada has, for at least a decade, also permitted the use of deltamethrin, at least in Atlantic Canada.  Cypermethrin, however, is prohibited. 

In the course of my investigation, I was only able to find out how much hydrogen peroxide is being used in aquaculture.
Health Canada figures (see table) show more than one million kilograms were sold in 2016. That placed the active ingredient among the top ten best-sellers that year (9th). It did not register in the top ten the following year. (The government counts products sold for aquaculture as "agricultural."



If that figure sounds high, amounts used in Norway - the world's largest producer of farmed Atlantic salmon - are "through the roof" by comparison. One source says, the industry in that country applied 132 million kilograms of H202 between 2009 and 2018. That would be at least than 13 times more per year than the Canadian usage!

So why do regulators continue to register these products?

The importance of aquaculture to human society is widely recognized. In their own studies, the researchers describe it as "One of the best prospects to help meet the growing need for protein in the human diet." 

The UN's Food and Agriculture Organization estimates, almost 19 million people worked in that sector in 2015. The world now produces about as much farmed fish as that taken in the wild. Once non-fish products (plants, shells and pearls) are added in - more than 100 million tonnes, or US$163 billion dollars worth of products, were produced by "ocean-farming" that year. It's considered the fastest-growing source of food for human consumption and is made up mostly of "finfish" such as the Atlantic salmon.

In Canada, government figures show, aquaculture employed 14 thousand people, full-time in 2009. For some reason, it's the most recent figure available. In 2013, production in the sector was valued at almost $1 billion. This country is ranked as the world's 4th-largest producer of farmed salmon. 

The website of the Canada Food Inspection Agency proudly states:
"Canada is one of the world's most trusted and respected food suppliers, trusted to provide safe and wholesome products and respected for our commitment to global food security. Canada's strong regulatory system forms the basis of this positive reputation."  (Emphasis mine.)

Are there better ways?

Researchers with Fisheries and Oceans Canada are among those looking for alternatives. They're trying to find out whether physical light traps and biological filters may be able to attract and remove the sea lice from the farms. There's no sign, yet that such methods are about to replace that heavy pesticide use, however. 

Meanwhile, research published about five years ago, seems to put an even finer point on the importance of finding alternatives - not just to pesticides - but to aquaculture itself!  Growth of the industry could actually be worsening the problem. Since sea lice numbers are proportional to fish size, "expanded salmon farming has shifted the conditions in favour of the parasites. Salmon farms are often situated near migrating routes of lice in the open ocean." 

And, as if that weren't enough, the lice are now showing resistance to three of the five compounds being used against them.

On January 11th, I e-mailed Canada's Minister of Health, Patty Hajdu (responsible for the Pesticide Management Regulatory Agency); Fisheries and Oceans Minister, Bernadette Jordan and the "Canadian Aquaculture Industry Alliance," to comment on my story. 

I did not get a substantive response.

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