Food Feature: Fish Farming Fallacies

by: bob zimway

Mon Nov 17, 2008 at 03:27:11 AM PST

And it is fraying now.

What are the alternatives?

Declining ocean fish stocks have led to a rapid growth in fish farming. Let's see how that's working out.

The total world aquaculture production contributes to the global fish supply. Aquaculture is one of the fastest growing food sectors, with production increasing from 10 million tonnes in 1990 to 29 million tonnes in 1997 (FAO, 1999). More than 220 species of finfish and shellfish are farmed today.

However, carnivorous farmed fish are fed on high levels of fish meal and fish oil and require a fish biomass input superior to the fish biomass produced. For the ten species of fish most commonly farmed , an average of 1.9kg of wild fish is required for every kilogram of fish raised. Unfortunately, there is an increase in the production trend of carnivorous fish (such as salmon or shrimp), rather than herbivorous or filter feeder fish. Small pelagic fish mainly provide the fish meal and fish oils used for aquaculture feed. Aquaculture's growing needs increase pressures existing on wild fisheries for small pelagic fish, which already suffer from overexploitation and are strained by climate changes resulting from the El Niño warming effect.

Pelagic fish are oily fish that live in the deep sea. This group includes herring, sardines and anchovies. Perfectly good fish in their own right, less likely to contain heavy metals as do the larger predator species, and in my opinion what we should be eating instead of tuna and farmed salmon.

Fish as food and fish food; a redundant article perhaps but I feel the need to show how the message is coming in from many authoritative sources:

WASHINGTON (Reuters) - One-third of the world's ocean fish catch is ground up for animal feed, a potential problem for marine ecosystems and a waste of a resource that could directly nourish humans, scientists said on Wednesday.

The fish being used to feed pigs, chickens and farm-raised fish are often thought of as bait, including anchovies, sardines, menhaden and other small- to medium-sized species, researchers wrote in a study to be published in November in the Annual Review of Environment and Resources.

These so-called forage fish account for 37 percent, or 31.5 million tons, of all fish taken from the world's oceans each year, the study said. Ninety percent of that catch is turned into fish meal or fish oil, most of which is used as agricultural and aquacultural feed.

Ellen Pikitch, executive director of the Institute for Ocean Conservation Science and a professor at Stony Brook University in New York, called these numbers "staggering."

A recent study (pdf) on salmon mortality in the Columbia and Fraser Rivers has put the spotlight on the effects of farmed salmon lice that infest wild smolts coming out of the Fraser. A 2005 study found a correlation between  proximity of fish farms and lice infestation. The fish farm industry refutes that and says that it is closely monitoring lice in its rearing pens. They apply lice killer, how and how much, I don't know, and what effect the chemicals have on the fish and on fish-as-food I don't know. But it's troubling.

Ocean Fish in Steep Decline
Fish farming get its food from the oceans. This fact leads one to ask how the sources of the world's wild fish are doing. Bummer.

A bleak warning from the UK:

A hidden catastrophe is unfolding off the coasts of Britain which could leave our seas filled with only algae and jellyfish, a leading conservation organisation warns today. The Marine Conservation Society says severe overfishing is the biggest environmental threat facing Britain and is having a profound effect on marine ecosystems. The warning comes in Silent Seas, a report released as the government prepares its marine bill for parliament.

The report comes the day after the International Council for the Exploration of the Seas, which advises Europe's politicians on fish stocks, warned that parts of the North Sea should be closed to mackerel fishing because stocks of the species could be on the brink of collapse.

Simon Brockington, head of conservation at the MCS, said: "There's a moral imperative: we simply shouldn't be living in such a way that drives species to extinction."

An excellent Nat Geo article describes a harrowing decline in valauble food species, exemplified by the crash of the bluefin tuna

Once, giant bluefin migrated by the millions throughout the Atlantic Basin and the Mediterranean Sea, their flesh so important to the people of the ancient world that they painted the tuna's likeness on cave walls and minted its image on coins.

But, uh oh, bluefin tuna makes the best sushi.

Over the past decade, a high-tech armada, often guided by spotter planes, has pursued giant bluefin from one end of the Mediterranean to the other, annually netting tens of thousands of the fish, many of them illegally. The bluefin are fattened offshore in sea cages before being shot and butchered for the sushi and steak markets in Japan, America, and Europe. So many giant bluefin have been hauled out of the Mediterranean that the population is in danger of collapse. Meanwhile, European and North African officials have done little to stop the slaughter.

"My big fear is that it may be too late," said Sergi Tudela, a Spanish marine biologist with the World Wildlife Fund, which has led the struggle to rein in the bluefin fishery. "I have a very graphic image in my mind. It is of the migration of so many buffalo in the American West in the early 19th century. It was the same with bluefin tuna in the Mediterranean, a migration of a massive number of animals. And now we are witnessing the same phenomenon happening to giant bluefin tuna that we saw happen with America's buffalo. We are witnessing this, right now, right before our eyes."

Popular species such as cod have plummeted from the North Sea to Georges Bank off New England. In the Mediterranean, 12 species of shark are commercially extinct, and swordfish there, which should grow as thick as a telephone pole, are now caught as juveniles and eaten when no bigger than a baseball bat. With many Northern Hemisphere waters fished out, commercial fleets have steamed south, overexploiting once teeming fishing grounds.

Africa's and Asia's surrounding seas are in steep decline. It's happening eveywhere. Bringing the crisis home, here's a bit of the fraying fabric that strikes the hearts of many in the Pacific Northwest. San Juan Islands orcas starving for lack of food.  

Right now, looking at the mess we're in in every direction, I'm beginning to get overwhelmed by how bad it is on every front. Economy, energy, food, climate, species extinction, population... population? No one talks about that anymore. I wonder though, when we will....

I'll leave it here.

UPDATE:
Here's more on farmed fish problems. Farmed fish have been shown to produce sea lice that harm wild stocks, and the Canadian government has taken this and other farmed fish issues seriously. Last week a production quota scandal arose over Canadian farmed fish.

A central-coast salmon-farming operation has drawn the wrath of environmentalists for violating its licence by pumping out unsustainably high numbers of fish. Living Oceans Society said Monday it was "appalling" that government documents show Mainstream Canada salmon farm sites in the Broughton Archipelago produced as much as twice the tonnage allowed in their licences.

Production limits are supposed to minimize the impact that animal waste from fish farms will have on the local environment, reduce the risks of hyper-concentrations of sea lice, and minimize the health risks that overcrowded sea pens would pose to the fish themselves.