Tag Archives: salmon

Salmon farming is costing billions in social and environmental damage

Salmon farming has produced negative externalities worth US$47 billion since 2013, ranging from pollution of marine ecosystems to high fish mortality, according to a new report. In other words, salmon farming is taking a huge toll on the environment, and that damage is costing everyone.

Image credit: Flickr / Malcolm Dickson

Salmon aquaculture is dominated by a small number of multinational producers operating in just four farming regions – Chile, Norway, Canada, and Scotland. It’s an industry that has grown dramatically in recent years, as the world’s appetite for fish is also growing. Not only it’s already the fastest-growing food production sector in the world, but continued global growth in demand is expected.

But the sector is not without controversy.

Hundreds of thousands of fish at a time are raised in pens suspended in the open sea. They swim inside the pens for up to two years before being “harvested” for our dinner plates. They are fed on processed feed and treated with medicines to ward off disease and infestations. The pens keep the fish enclosed but allow parasites to get in. To make matters even worse,

The report “Dead Loss” by the consultancy Just Economics highlighted the economic, environmental, and social externalities caused by salmon farming, amounting to almost $50 billion. Of this cost, 60% is supported by producers — but 40% is indirectly supported by the wider society. This questions the positive image usually promoted by the farming companies, the researchers argued.

Mortality rates on salmon farms were found to be extremely high, with parasites (and their treatments), disease (and their treatments), pollution, and escapes being the major contributing factors. The combined cost of mortalities since 2013 in Norway and Scotland, the only countries with figures on this, was estimated at $9.8 billion in the report.

Even when parasites and disease don’t result in deaths, their treatment is costly, and the presence of lice, in particular, is a barrier to sector expansion. There are also clear consumer concerns about the use of medicines and chemicals to control them. Lice and disease spread are hastened by high stocking densities which are designed to increase the productivity of farms.

“Aquaculture activities are an interconnected part of the ecosystem in which they exist, and salmon farms make use of ‘free’ coastal ecosystem services such as clean water, appropriate temperatures, nutrient levels and so on. They also contribute to their deterioration, however, due to local pollution impacts from uneaten feed and feces, which are directly discharged into the marine environment,” the report reads.

Salmon farming is also generating substantial environmental pressure in local environments, and Atlantic salmon can only be farmed under certain conditions. As seas warm and available locations become exploited, the industry is running out of viable sites for new farms.

The main social issue listed by the researchers was the impact on salmon welfare. Researchers conclude that farm profitability and salmon welfare are inextricably linked, so farmers have a long-term motivation to keep salmon healthy. In the short-term, however, there may be a financial incentive to take shortcuts with fish husbandry. Over time, however, these lead to disease, lice, stress, and ultimately higher mortality rates, which also result in financial losses.

Moreover, there are strong (and growing) consumer preferences for high fish welfare, especially in Europe. A recent study found that the average European consumer would be willing to pay 14% more for salmon with higher welfare standards, and other areas seem to be picking up the same trend.

“The demand for seafood is expected to increase in coming years and part of this will have to be met by increased aquaculture production. Fish farming has the potential therefore to be a significant source of social, economic, and environmental value but farming practices matter greatly and determine whether the industry can be considered a net loss or net benefit to society,” the report reads.

In conclusion, the researchers also listed a set of recommendations for changes to be carried out in the sector. Economic benefits of salmon farming have to be balanced against other coastal industries such as tourism, angling, and wider environmental impacts, while governments should be prepared to support alternative technologies that improve social and environmental standards.

Meanwhile, consumers should be prepared to pay more for salmon where their economic circumstances allow, and/or to consume it less frequently. As part of this, consumers could seek out alternatives to carnivorous fish such as molluscs that provide dietary and economic benefits at lower social, economic, and environmental costs.

Reacting to the report, a spokesperson of Mowi, a Norwegian salmon company, told The Guardian: “We are pleased that the report finds that, when considering the full range of benefits and impacts, the business of salmon farming demonstrates overall positive benefit. We agree that there are opportunities for continued improvements for our business.”

Coho spawning.

Greenland, Faroe Islands to stop commercial fishing of wild salmon for 12 years

Greenland and the Faroe Islands will completely stop commercial wild salmon fishing for the next 12 years. The move aims to allow the species to regenerate and return to rivers in Canada, the United States, and Europe.

Coho spawning.

Coho spawning on the Salmon River, Idaho.
Image credits Bureau of Land Management Oregon and Washington / Flickr.

It seems that one of the worst qualities an organism can have in the twenty-first century is being tasty. Case in point: wild salmon. While there are several wild species belonging to the family Salmonidae, nine of them are commercially-important — and they aren’t faring very well at all. Overfishing has left wild populations on the brink of collapse, with potentially disastrous consequences both on an environmental as well as economic and social level.

Teach a man not to fish

In an effort to allow Atlantic populations some time to recover, the Atlantic Salmon Federation and North Atlantic Salmon Fund have convinced Greenland and the Faroe Islands to stop commercial salmon fishing for the next 12 years. These two countries were selected as their coastal waters hold feeding grounds that are crucial for wild salmon, harboring many individuals from endangered populations in rivers like Saint John in New Brunswick and the Penobscot in Maine.

In exchange, the two organizations have pledged financial support for alternative economic development in Greenland, scientific research, and education projects focused on marine conservation.

For now, the exact details of this financial agreement are being kept confidential — but the Atlantic Salmon Federation is adamant that not government money will be involved. All funding will be raised by the two organizations or will come from private donations.

Greenland fishermen will also be allowed catches up to 20 metric tonnes per year for personal and family consumption only. Even so, the deal is estimated to allow over 11,000 mature salmon to return to home rivers in 2019 instead of ending up in a net.

And nothing sums up why we need to do this better than this somewhat obvious but very valid observation of Chad Pike, chairman of the North Atlantic Salmon Fund:

“The best way to save North Atlantic salmon is to stop killing them,” he told The Globe and Mail. “This deal does that in meaningful numbers.”

“Significantly reducing the harvest of wild Atlantic salmon on their ocean feeding grounds is meaningful and decisive,” adds Bill Taylor, president of the Atlantic Salmon Federation.

Wild salmon stocks have steadily dropped to alarming levels in the past few years, caught between overfishing, ecosystem shifts caused by climate change, and other run-of-the-mill human meddling. Stocks have dwindled from roughly 1.8 million individuals returning on salmon runs in North America in the 1970s and ’80s to under 418,000 individuals in 1990, and the sustained efforts of the Atlantic Salmon Federation (about which you can read more here) have managed to prop up their numbers to roughly 600,000 in recent years.

Still, the situation is far, far from improving. Salmon runs across the US are at an all-time low: in California, Oregon, Idaho, Washington, and southern British Columbia, many bring less than 10% of their historical numbers. Others have simply stopped happening altogether, according to this paper by Robert T. Lackey from the Department of Fisheries and Wildlife. This paragraph puts how dire the state of wild Atlantic salmon is today into chilling perspective:

“Every few years, there is a media celebration of ‘record’ salmon runs, but these temporary blips are due mainly to favorable ocean conditions coupled with a recalibration of what constitutes a ‘record’ run. If doubling a run from 2% to 4% of the historical level qualifies as a record run, then we are often there, however modest the increase may be,” he writes.

“More sobering, the majority of such runs are usually hatchery-bred fish. Nowadays wild salmon comprise less than a quarter of many West Coast salmon runs.”

Delegations from Greenland and the Faroe Islands will declare the zero commercial quotas at next month’s international summit in Portland, Maine, which will work retroactively to April 30.

The 12-year moratorium should cover two whole generations of wild Atlantic salmon, allowing them to reproduce in peace. Both organizations, as well as officials from the two countries, expect that this will help significantly raise population numbers in the long term.

Ancient Alaskans feasted on salmon 12,000 years ago

At least 15 cooking hearths have been unearthed in Alaska, revealing surprising facts about the lives and diets of the Sub-Arctic hunters of the Ice Age.

In 2013 and 2014, researchers expanded the dig at Upward Sun River to study the relationship between the residential structure and the hearths. (Photo by Ben Potter)

The hearths, which have been dated to at least 11,800 years old, contain numerous salmon remains. Archaeologists believe this is the earliest evidence of salmon cooking in the New World.

Finding salmon in Alaska, even during the Ice Age, might not seem surprising, but scientists believed that Alaskan hunters mostly ate what they hunted on land – namely bison, elk, and mammoths. However, in light of this recent find, fish seems to have also been valued as a great resource.

“Our results demonstrate that salmonid and freshwater resources were more important for late Pleistocene hunter-gatherers than previously thought,” the team writes in their report on their findings, in the Proceedings of the National Academies of Science.

Modern science for ancient studies

In recent years, archaeology has greatly benefitted from technological advancements. In this particular case, they used isotopic analysis to study the charred remains found in the hearth. Judging by the presence of several isotopes, scientists can trace the origin of whatever was burned (to an extent). They can also date it. In this case, they traced it back to 11,800-year-old salmon.

“It’s quite new in the archaeology field [the technology],” said Kyungcheol Choy, the University of Alaska-Fairbanks, researcher who led the study, in a press statement. “There’s a lot in these mixtures that’s hard to detect in other ways.”

This makes it the oldest proven salmon consumption in the Western Hemisphere, but it’s not the only thing they can find through the technology. For instance, aside for the 10 hearths which contained heavy salmon residue, others contained many traces of freshwater fish and land animals, suggesting that separate pits were used for preparing different kinds of food, consistently over the course of thousands of years.

This adds greatly to our understanding of the ancient people’s lives, because in a way, modern archaeology is a lot like crime scene investigation. It’s not so much about finding new things and structures, because most of them have already been found. Instead, the focus is on understanding these people, understanding what their life was like and how they developed as population. Of course, diet plays a key role in any population’s lifestyle.

“Our findings reveal that analysis of organic residues from hearth sediments can have great utility for reconstructing dietary trends and subsistence practices among mobile hunter-gatherers, particularly in contexts where faunal remains are poorly preserved,” they write. “It’s an awesome look at how we can merge disciplines to answer a question,” Potter added in the press statement.

Journal Reference: Choy, K., Potter, B., McKinney, H., Reuther, J., Wang, S., & Wooller, M. (2016). Chemical profiling of ancient hearths reveals recurrent salmon use in Ice Age Beringia Proceedings of the National Academy of Sciences, 113 (35), 9757-9762 DOI:10.1073/pnas.1606219113

Salmon hatcheries cause substantial, rapid genetic changes

The evidence is pilling up that fish grown in hatcheries are very different from those in the wild. A new study found that after only one generation, hatchery salmon have significant genetic changes.

A hatchery on a shrimp farm in South Korea. Photo by NOAA.

A fish hatchery is a “place for artificial breeding, hatching and rearing through the early life stages of animals, finfish and shellfish in particular”. With fish stocks being overexploited or depleted in many parts of the world fish hatcheries have become a blooming business, but there are severe problems with aquaculture – including genetic problems.

The first such problem is that maintenance of a small number of broodstock can cause inbreeding and potentially create unhealthy, malformed populations. Over the course of several generations, the effects of inbreeding can be devastating. However, a new study found that even after one generation big differences emerge.

The research, published today in Nature Communications, found that between wild fish and their hatchery offspring over 700 genes exhibit different activity. Oregon State University in collaboration with the Oregon Department of Fisheries and Wildlife claim that this is strong evidence that hatchery fish simply aren’t like wild fish.

“A fish hatchery is a very artificial environment that causes strong natural selection pressures,” said Michael Blouin, a professor of integrative biology in the OSU College of Science. “A concrete box with 50,000 other fish all crowded together and fed pellet food is clearly a lot different than an open stream.”

It’s not yet clear what traits are passed on or how the change in evolutionary pressure affects the fish, but there are clues that hatchery fish are weaker and metabolize their food differently. Because they are crammed in a very small space, diseases and injuries are also more common than in the wild.

“We observed that a large number of genes were involved in pathways related to wound healing, immunity, and metabolism, and this is consistent with the idea that the earliest stages of domestication may involve adapting to highly crowded conditions,” said Mark Christie, lead author of the study.

These genetic changes are substantial and surprisingly rapid, the study finds. That evolution could cause such a big change in only one generation is a surprise.

“We expected hatcheries to have a genetic impact,” Blouin said. “However, the large amount of change we observed at the DNA level was really amazing. This was a surprising result.”

Reactions to FDA approving genetically engineered salmon

A few days ago, the FDA approved the genetic engineering of modified Atlantic salmon variety. This is the first food animal that was genetically modified that the FDA approved for human consumption and farming; the gene alteration would make it grow much faster. Public reactions have been mixed, as expected. This could be a very good move, greatly reducing the stress on wild populations, but people are always reluctant when it comes to GMOs – especially animals.


Reactions have been interesting from the scientific community as well – and generally positive. Dr. Garth Fletcher, Professor Emeritus and Head of the Department of Ocean Sciences at the Memorial University of Newfoundland hailed it as a laudable achievement:

“This approval is good news for all academic researchers interested in genetic modification of animals being bred for human consumption. The pioneering efforts of AquaBounty working with FDA regulatory authorities has demonstrated that with care, good science, and patience, innovative research in this somewhat controversial field can be taken from the laboratory bench to the market place.”

Mark Abrahams, Dean of Science & Professor, Department of Biology / Ocean Sciences, Memorial University of Newfoundland has been more circumspect, but still positive:

“In my opinion, the review process undertaken by the FDA has been extremely thorough so I think it reasonable to assume that the conclusions they have drawn and the recommendations they have made are well supported by the evidence. From that perspective there is no evidence that these fish pose a risk to human health but time will tell whether they will be accepted by consumers.”

But Dr. Anne Kapuscinski, Professor of Environmental Studies at Dartmouth College was a bit more circumspect.

“This approval shows us how the FDA will apply the drug law to more applications to farm genetically engineered salmon. More applications are coming because this first approval applies to a small farm in Panama that will barely make a dent in the global market of farmed salmon. I see incremental improvement in how the FDA applied science in the environmental assessment, but I don’t see the scientific quality required to assess many larger applications.”

Indeed, this is a valid point – what kind of a difference can this make on a global (or even regional) scale for fish populations? Perhaps even more importantly, how does that compare to the risk of the fish escaping in the wild?

“This worries me because the drug law forces the FDA to keep secret a genetically engineered animal’s environmental assessment unless the applicant wants it to be public. The environmental impact of this GE salmon approval hinges on keeping it from getting out into nature. The FDA concluded it is environmentally safe because the hatchery in Canada and farming operation in Panama have multiple, complex barriers to escape, but it will be a real challenge to scale up this approach to many and larger salmon farms. This is why my comments to the FDA urged for a quantitative analysis of possible failures in the confinement measures, which are easy to do for this application. I urged the FDA to model the scientific rigor the agency will expect in future applications. The FDA seems to have read my advice but chose to interpret it very narrowly and decided to not require a quantitative failure mode analysis.”

But perhaps the more important thing about this decision is not that it allows the development of genetically modified salmon, but that it creates a precedent. Although breeders have selectively bread their animals for centuries, this is the first time a direct genetic modification has been approved. Eric Hallerman, Professor of Fish Conservation, Virginia Tech University highlights this point:

“This approval follows extensive review of food safety and environmental safety under the authority of the U.S. Food, Drug and Cosmetics Act. The action allows pilot-scale production at these specific facilities, which will be critical for quantifying the economics of production and the efficacy of confinement. Yet, the significance of the action is that it marks the first approval globally for production of genetically modified animals for purposes of food production and sale.”

But he also underlines another interesting aspect – that of labeling.

“Today’s action is significant for another reason, as FDA also announced draft guidance on the voluntary labelling of food derived from the product. Much controversy has focused on whether and how foods derived from biotechnology should be labelled. While studies have shown that salmon products derived from the AquAdvantage salmon are no different from those derived from conventional production, some consumers have argued for a ‘right to know’ how food products were produced.”



FDA approves first genetically modified animal: a salmon that grows twice as fast

After five years long of pondering, the FDA finally gave the green light for a genetically modified Atlantic salmon variety. This is the first food animal that was genetically modified that the FDA approved for human consumption and farming. The salmon has genes from another salmon species, as well as an eel-like fish, which allows it to grow to market size in half the time it would usually take. This means it saves twice as much time and resources as conventional salmon, with no nutritional or health drawbacks, the FDA says.


Image: Pixabay

The salmon was engineered by Massachusetts-based AquaBounty Technologies. Initially it was developed as a fast-growing variety by a group of Canadian public university scientists, and regulatory approval was asked for the past two decades. Five years ago, the U.S. Food and Drug Administration deemed the salmon safe. The agency wanted however to ‘get everything right’, said  FDA policy analyst Laura Epstein. It makes sense after all, since an unprecedented decision requires unprecedentedly long breath time.

The modified Atlantic salmon has a Pacific salmon gene for faster growth and a gene from the eel-like ocean pout that promotes year-round growth. For now, the fish will be grown in two designated land-based and contained hatcheries in Canada and Panama. To furthermore isolate the risk of introducing a GMO animal to the wild, the FDA requires farmers to grow only sterilized females. The FDA has also issued draft guidelines on how food manufacturers could identify whether the salmon in their products are genetically modified. The FDA doesn’t mandate producers, however, to label the salmon based product as genetically modified since it’s  virtually indistinguishable from conventional salmon.

“The FDA scientists rigorously evaluated extensive data submitted by the manufacturer, AquaBounty Technologies, and other peer-reviewed data, to assess whether AquAdvantage salmon met the criteria for approval established by law; namely, safety and effectiveness. The data demonstrated that the inserted genes remained stable over several generations of fish, that food from the GE salmon is safe to eat by humans and animals, that the genetic engineering is safe for the fish, and the salmon meets the sponsor’s claim about faster growth,” the FDA said in a statement.
“In addition, FDA assessed the environmental impacts of approving this application and found that the approval would not have a significant impact on the environment of the United States. That’s because the multiple containment measures the company will use in the land-based facilities in Panama and Canada make it extremely unlikely that the fish could escape and establish themselves in the wild”

Consumers and environmental groups are opposed to the decision, however.  Food & Water Watch is lobbying Congress members to roll back the FDA approval. It will also allegedly file a lawsuit, along with other groups, to block the GM salmon from reach the consumer market. That’s if there’s a market in the first place. Already, major retailers across the US have announced that they will not stock GM salmon, including Kroger Co, Trader Joe’s, Whole Foods and Target. In fact, in 2010 Target withdrew farm-raised salmon in favor of wild-caught salmon. At the time, Target spokeswoman Molly Snyder said this was the first step in a long-term commitment to improving the sustainability of our seafood assortment. This statement is far from being rooted in reality, though. Fishing wild salmon may be sustainable if you’re an Inuit with a boat, not a 1,000 tonne salmon harvester.

Once a luxury food reserved for special occasions like Christmas and New Year’s Eve, salmon has gradually become available year-round in supermarkets, in large quantities and at reasonable prices. Wild Atlantic salmon stocks in North America, Europe and the Baltic have been over-exploited since the 19th century and in many regions the species has disappeared completely. The salmon isn’t alone. Cod fisheries around the US, and especially in the Gulf of Maine have reached catastrophic levels – only 3% of sustainable levels. In 2010, an University of British Columbia study found fisheries have no more place to expand.

Recognizing these sort of issues that threaten our food supply,  80 scientists and biotech industry executives sent a letter to President Barack Obama urging him to support the approval of GM salmon.

Again, this is the first GM food animal approved by the FDA. It will, of course, set a precedent, but that doesn’t mean we’ll get to see GM pigs, chicken and cattle too soon. The salmon was approved because the breeding conditions are 100% contamination free.

Biologists fear salmon kill in Klamath river

It’s a tough year for salmon all around the world – now, a new health advisory issued by the U.S. Geological Survey, Bureau of Reclamation and PacifiCorp raises concerns about the future of salmon in the Klamath river in Oregon and California.

The Klamath is the second largest river in California, draining  an extensive watershed of almost 16,000 square miles (41,000 km2). The river used to contain vast freshwater marshes and a stunning biodiversity, but in recent years, it is largely agricultural. Birds and fish have been especially threatened, but until recently, salmon have adapted surprisingly well to rising temperatures and high acidity levels.

However, there’s only so much they can adapt – and the presence of blue-green algae toxins in the water bodies might be the final straw. Poor water quality has already been reported in several areas by federal, state and tribal officials monitoring fish runs in the Klamath River. Low flows and higher water temperatures have brought on an early onset of the lethal parasite Ichthyophthirius multifiliis, known as Ich (pronounced “ick”).

“The risk factors this year are piling up,” Mike Belchick, biologist for the Yurok Tribe, said Wednesday. The tribe depends on Klamath River salmon for food and ceremonies.

Yurok Senior Fisheries Biologist Michael Belchik explained that not much is known about ick.

“There was none detected for 11 years and then in 2014, it just shows back up,” he said. “It’s alarming — [the spread of the disease] goes from zero to 100 so fast, and that’s what’s causing us to worry right now.” Aquariums and hatcheries encounter ich regularly, as fish within those confines are often in warmer water and denser conditions, and treat it most commonly with salt or formaldehyde, neither of which are viable for river treatment. The only immediate, albeit temporary, solution is to increase flow, Belchik said. Without the release of cooler water allowing the fish to spread out, he continued, the situation “could get really bad … Some possibilities are catastrophic.”

The underlying problem still remains the lack of water – agriculture simply requires too much water. Water has always equaled riches in one form or another in the Golden State and the diversion of water from Klamath indicates a larger problem: the over-usage of natural resources for human purposes. The salmon, like many other animals, will likely pay the price.

Dramatic Californian Drought Forces Salmon to Take the Highway

California’s record drought has completely dried off large swaths of rivers, including the San Joaquin River, which means that juvenile salmon can’t actually reach the sea. In a desperate effort to save an entire generation of hatchlings, authorities are transporting them by truck, on the highway.

Here, the Enterprise Bridge spans the same reservoir, which has dwindled to a mere trickle in 2014 as California is forced to draw alarming amounts of water from its vanishing reservoirs.

“Bone dry. Bone dry,” said fish biologist Don Portz of the U.S. Bureau of Reclamation, describing the Sao Joaquin River. Portz is six years into an effort to restore the southernmost salmon stream in the U.S., the Central Valley’s San Joaquin River.

California is currently experiencing the worst drought in at least 1,200 years – and the effects are easy to see everywhere. Governor Brown declared a drought State of Emergency in January and directed state officials to take all necessary actions to prepare for water shortages; there are water shortages in several areas, mandatory water saving regulations have been implemented, and of course, the wildlife is greatly suffering – especially fish.

Young salmon are loaded into a barge Wednesday at Mare Island, California. They have been trucked from the Coleman National Fish Hatchery near Anderson and placed onto the barge that will float them into San Pablo Bay to be released. Source:  Rich Pedroncelli / Associated Press

Young salmon are loaded into a barge Wednesday at Mare Island, California. They have been trucked from the Coleman National Fish Hatchery near Anderson and placed onto the barge that will float them into San Pablo Bay to be released. Source: Rich Pedroncelli / Associated Press

Drought-ridden rivers mean the young salmon can’t perform their annual passage from the river to the Pacific Ocean – so as a last resort measure, humans tried to step in. State and federal wildlife agencies are coordinating the biggest “fish-lift” in the history of the state, and perhaps in the history of the world, hauling the fish in huge tankers.

“It’s huge. This is a massive effort statewide on multiple systems,” said Stafford Lehr, chief of fisheries for the California Department of Fish and Wildlife, which since February has been rolling out four to eight 35,000-gallon tanker trucks filled with baby salmon on their freeway-drive to freedom.

But this is only a one time solution – it can’t work sustainably. As part of  their lifecycle, salmon would reach the ocean, grow up, then to up the river again to lay eggs. If the river is dried up, they will again find themselves helpless.

“You give them that taxi ride down, they make it to the ocean, and come back” in a few years for trapping and a taxi ride back up to spawning grounds, Portz said.

This operation is also risky –  In January, Oregon authorities charged a trucker with drunken driving after he hit a pole and flipped 11,000 juvenile salmon out on the roadway.

Also, authorities can’t transport all the salmon, but the ones that will be left behind will be picked up and temporarily placed in fisheries, to wait out the drought. But will the drought actually end? That’s another discussion.

Isotopes inside salmon ear tell a fishy story

According to a new study, just like tree rings carry with them hints about previous dry or rainy years, bones in fish carry with them a specific signature which records the chemical composition of the waters they used to live in.

A cross-section of a salmon otolith, also known as a fish ear stone or fish ear bone. Scientists measured Strontium ratios and identified the waters in which the fish lived for its entire life. The new fish-tracking method may help pinpoint critical habitats for fish threatened by climate change, industrial development and overfishing. Credit: Sean Brennan, University of Washington
Read more at: http://phys.org/news/2015-05-chemical-tags-ear-bones-track.html#jCp

Most vertebrates, especially fish, have what is called an ‘otolith’ – a specific bony structure inside the inner ear. The  otolith accretes layers of calcium carbonate and gelatinous matrix throughout the entire life. The accretion rate varies with growth of the fish – often less growth in winter and more in summer – which results in the appearance of rings that resemble tree rings; and just like with tree rings, scientists can figure out the age. Another interesting fact is that the otolith isn’t really digestible, so it often remains stuck in the digestive tract of fish-eating animals, and scientists can therefore reconstruct their eating habits.

But whenever the otolith grows and accretes more calcium carbonate, it also traps in other elements – extremely small fractions of the chemical makeup of the waters in which the fish live in. Specifically, it traps in specific isotopes, in specific quantities; by analyzing these isotopes, researchers are now able to reconstruct where the fish was born and where it traveled for its entire life.

Sean Brennan from the University of Washington and lead author explains:

“Each fish has this little recorder, and we can reveal the whole life history of the fish from the perspective of the otolith. Each growth ring is a direct reflection of the environment the fish was swimming in at the time it was formed.” Brennan completed the study as a doctoral student at the University of Alaska Fairbanks. He is now a postdoctoral researcher in the University of Washington’s School of Aquatic and Fishery Sciences.

Specifically, they looked at the trace element strontium. Strontium is a very reliable element for this type of reconstructions because it almost never alters and strontium levels vary greatly depending on the age and structure of the bedrock. In other words, by looking at how the strontium in an area looks like you can figure out (to some extent) where it comes from. But it wasn’t an easy feat. Thure Cerling, also an author, explains:

“There are literally thousands of measurements on each otolith,” Cerling says.

Geochemist Diego Fernandez further adds:

“They’re like microexplosions. You create tiny, tiny particles that are carried into the mass spectrometer.” By showing how the ratio of strontium-87 to strontium-86 changed over time, “we get the entire life history of the salmon,” he says.

Some areas more than others are better candidates for this type of analysis, but researchers wanted a challenge – so they chose Alaska.

“Alaska is a mosaic of geologic heterogeneity,” he added. “As long as you can look at a geologic map and see rocks that are really different, that’s a good potential area.”

One of the many tributaries to the Upper Nushagak River. Credit: Sean Brennan, U of Washington

About 200,000 Chinook salmons make their way to the breeding grounds in Bristol Bay every year. When the eggs hatch in the spring, the little salmons spend a whole year in the river before venturing to the Bering Sea, and ultimately, the Pacific Ocean.

This is not only an extremely exciting find, but one that can have a great effect on fish populations throughout the world. By analyzing several otoliths, scientists can now see if their migratory patterns have remained similar, or if they have changed – likely due to some stress. From a conservation standpoint, that’s a game changer.

“This is science responding to a societal issue and need,” said co-author Christian Zimmerman, U.S. Geological Survey ecologist and chief of water and interdisciplinary studies at the USGS Alaska Science Center in Anchorage. “Using this approach, we will be able to map salmon productivity and determine how freshwater habitats influence the ultimate number of salmon. With declines in Chinook salmon in Western Alaska, fishery and land-use managers need better information about freshwater habitats to guide conservation.”

But it’s not just fish – the same technique could be used for other animals. Strontium is known to accumulate in bird feathers and teeth and also survives even after being fossilized. It could help us understand moving patterns better than ever.

Journal Reference: Sean R. Brennan, Christian E. Zimmerman, Diego P. Fernandez, Thure E. Cerling, Megan V. McPhee, Matthew J. Wooller. Strontium isotopes delineate fine-scale natal origins and migration histories of Pacific salmon. DOI: 10.1126/sciadv.1400124

Obama bans drilling in Alaska’s Bristol Bay, citing risk to salmon fishery

In what is not only a laudable initiative but also an interesting precedent, president Obama has declared a large swath of southwest Alaska’s coast off-limits to oil and gas drilling. He stated that the environmental risks are the main reason why he is taking this measure – the oil exploitation could endanger fisheries which are vital for the area.

“It is a beautiful natural wonder and it is something that is too precious to just put out to the highest bidder,” Obama said, announcing the drilling ban. He also called the 250-mile-long stretch of coastline “one of America’s greatest natural resources.”

Bristol Bay is located in South-Western Alaska. The is 400 km (250 mi) long and 290 km, (180 mi) wide at its mouth; it is home to the world’s largest sockeye salmon fishery as well as strong runs of chum salmon, silver salmon and king salmon, each occurring seasonally. Kings are usually the first to run up the river followed by reds and chums. The major industries associated with the area are sport fishing and tourism, but recently area has also experienced significant interest in oil and mineral development. The Obama ban puts a stop to oil exploration there.

The decision means that federal water will remain permanently off limits for oil and gas exploration. While the decision was expected, it was still hailed by workers in the area and environmentalists.

“This action ensures Bristol Bay will remain America’s fish basket for generations to come, unspoiled by additional industrial activity and safeguarded for the benefit of Alaskans and all Americans,” said Michael Conathan, director of ocean policy for the ­Center for American Progress, a Washington think tank.

However, mineral exploration in the area is still debatable. The EPA is considering whether to preemptively ban mineral extraction in the region, and this decision gives a strong indication of what the EPA will decide.


Sockeye migrating up the Fraser River (conserv.org)

Salmon uses magnetic field to guide itself back home

Sockeye migrating up the Fraser River (conserv.org)

Sockeye migrating up the Fraser River (conserv.org)

For years scientists have been studying the salmon migration path, which is one of the most fascinating, yet dangerous. Once it’s born in its freshwater breeding location, the salmon heads for salt water in the ocean, before it returns to its exact  freshwater stream of birth in order to restart the process – a journey that lasts for years and carries the salmon thousands of miles. How they manage to navigate so precisely is still a subject for debate, but recently scientists at Oregon State University have proven that a very important signal is Earth’s magnetic field.

“For salmon to find their way back home, they remember the magnetic field that exists where they first enter the sea as juveniles, and once they reach maturity, they seek that same coastal location, with the same magnetic field,” Oregon State University researcher Nathan Putman told BBC News. “In other words, salmon remember the magnetic field where they enter the ocean and come back to that same spot once they reach maturity.”

The idea that salmon use Earth’s magnetic field to navigate to their original freshwater streams isn’t new, by far, it has actually been regarded as acceptable by the community for years. However, this is the first time the theory has been proven.

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For their study, the researchers chose to look at the sockeye salmon, which is native to the northern Pacific Ocean and has the most grueling journey out of all salmon species. Data collected by fisheries for the past 56 years was used in order to find where the largest proportions of salmons could be found in which areas of the streams. Luckily a natural experiment had a deciding factor. Near the mouth of British Columbia’s Fraser River is 460-kilometer-long Vancouver Island, which lies right in between the sockeye salmon migration path back home.


Once the salmon reach Vancouver Island it is presented with two choices – either swim around it north or south. After studying the  federal fishery data, the researchers found the most salmon chose to swim by the route where the magnetic field strength was more similar to that of the river mouth when they’d left, two years before.

According to Putman, other marine animals in migration, like sea turtles or seals and whales, may be picking up the same magnetic cues as the salmon. “It seems unlikely that salmon are the only ones who’ve come up with this really good idea for finding your way home – it likely evolved in multiple lineages,” he said.

“In general, we know much less about how salmon complete the ocean part of their migration compared to fresh water,” said quantitative ecologist Chloe Bracis, a graduate student at the University of Washington who also studies geomagnetic salmon navigation. “The authors cleverly take advantage of spatial differences in a salmon migration route to provide the first solid evidence that salmon use geomagnetic cues to direct their oceanic migration.”

While the study clearly proves magnetic cues are used by salmon when navigating through fresh streams, it still doesn’t prove how it’s able to navigate through the endlessness of the open ocean. Other studies, including the present one at hand, also describe how the salmon uses water surface temperature, as well as chemical cues to guide themselves back to their breeding grounds. Still, these might just be a few tools in the fish’s navigation gear.

“They might use … a sun compass or other cues,” Bracis said. “Geomagnetic cues could guide them to the vicinity of the river, then they would need to switch to other local cues to navigate the rest of the way to the river mouth or through the estuary.”

Findings were reported in a paper published in the journal Current Biology.

via Wired