Omega-3s used in supplements come from a variety of sources, including algal oils. But still the lion’s share of the world’s servings of EPA and DHA come from the Peruvian anchovy fishery, which is perennially the world’s largest in terms of overall biomass harvested.
Anchovies provide a highly attractive fatty acid profile; in fact the 18:12 EPA to DHA base specification for human grade omega-3 oils is taken from what these fish naturally provide. And the fish are low on the food chain, being a short lived forage fish species. Add to that the fact that they are filter feeders, taking their microscopic food directly from the water.
When you factor in their incredible abundance—trillions of individuals— you have an almost perfect raw material, one that can be harvested and will reliably regrow year after year.
Harvesting fish that are low on the food chain is generally thought to have fewer environmental downsides. Salmon (another popular, though much smaller, source of omega-3s oils for supplements) are by contrast a predator high on the food chain.
Concerns about bird populations
But cutting out a big chunk of the food available in a given ecosystem is not without consequences of its own. In particular the effects on the populations of the predators of those fish has been called into question in recent years. An influential report published in 2013 called Little Fish, Big Impact by an organization called the Lenfest Forage Fish Task Force raised the alarm about the low populations of seabirds along the coast of Peru. These birds were once so numerous that they gave rise to a whole industry of harvesting their guano as fertilizer.
Fisheries researcher Ray Hilborn of the University of Washington is in the midst of two projects in the Peruvian fishery, one of which is looking specifically at the bird population effects.
Hilborn said three bird species are principally involved: boobies, penguins and cormorants. On the surface, Hilborn said the population numbers could give cause for concern.
“We are trying to examine the impact of the that fishery on these three main bird species,” he said. “With the cormorants in particular there seems to have been an effect. They have declined from about 20 million to about 3 million.”
Not a simple equation
But Hilborn cautioned against drawing simple quid pro quo type conclusions, such as, you caught too many fish, so the birds starved. In other research Hilborn and his collaborators have done on bird predator/fish interactions, he noted that in some cases birds take forage fish at different stages of their life cycle (read: younger, smaller) than what fishermen target.
That doesn’t seem to be a factor in the anchovy fishery, as the fish don’t get very big and only live about a year. Nevertheless, Hilborn said the start of the cormorant decline seems to have predated the big ramp up in the fishery in recent decades, so while fewer fish at times might have exacerbated whatever is going on, it may not have actually ‘caused’ it.
And still to be determined is exactly how the abundance of fish affects the birds’ feeding success, Hilborn said.
“It could be something like that with every dive they only get two fish instead of five fish,” he said.
And Hilborn said more data needs to be gathered on how fishing affects the local availability of the fish as opposed to their overall abundance. The birds and the fishermen are both after the same thing: the densest schools of fish. Seining operations tend to break up these agglomerations, leaving the birds to presumably have to travel greater distances to hunt for more dispersed pockets of fish. The boobies in particular and to some degree the penguins seem to able to hit this kind of curveball more easily than do the cormorants, Hilborn said.
Hilborn’s other project in a management assessment effort that is aimed to help the Peruvian fishery regulatory body IMARPE improve its operations. While the organization seems to have been successful overall in managing the fishery, there have been repeated questions raised about the transparency of the process.
“The whole management process could be much more transparent. The setting of quotas still has a lot of politics in as opposed to relying on the data,” he said.
“But overall, if your primary goal is the management of the harvest, I’m not sure they could have done much better than they have done,” Hilborn said.
Ellen Schutt, executive director of the Global Organization for EPA and DHA Omega-3s (GOED), echoed Hilborn’s assessment of the overall health of the fishery.
“I always give the Peruvian anchovy fishery and the Antarctic krill fishery as examples when people ask me about the sustainability of omega-3s,” Schutt said.
Schutt said recent data supports the notion that IMARPE is taking a cautious, responsible approach to managing the fishery and does not hesitate to take bold action when it’s called for.
“At least twice in the past five or six fishing seasons (there are two per year) they’ve closed the entire season and have not allowed any harvest,” Schutt said.
Fluctuations are the norm
While that kind of drastic action might seem to argue for a fishery that’s in crisis, Hilborn said big fluctuations are the norm when looking at forage fish populations. The data on the Peruvian fishery only goes back a few decades, but Hilborn said there are records of sardine abundance off the coast of California that span hundreds of years. And that is an analogous fishery: a fast growing, small species feeding on nutrients brought up by a cold, upwelling ocean current.
“We have a thousand year record of California sardines and they come and go and there were decades where there were almost none of them. We’ve seen them go from 20 million or 30 million tons down to 3 million or 4 million tons,” he said.
The reasons for these kind of fluctuations are still not perfectly understood. In the case of Peru, El Niño events have a definite negative impact, Hilborn said. But the fish have weathered those oscillations for millions of years. While fluctuations in the abundance of fish has been noted for hundreds of years, the science of why this happens is still in its infancy, Hilborn said.
“We just passed the 150 birthday of (Norwegian fisheries scientist) Johan Hjort,” Hilborn said. “He was the one who really discovered that within a given species there were weak year classes and strong year classes. The bottom line is we really still don’t understand why that happens,” he said.
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