Eco-impact of wild seafood less than that of poultry, beef
Scientist calculates that the “edible protein energy return on investment” of 29 North Atlantic fisheries is much higher than any type of livestock.Posted Feb 10, 2011
At a recent Seafood Summit in Vancouver, B.C., Professor Ray Hilborn, Ph.D., a world-famous fisheries researcher from the University of Washington’s School of Aquatic and Fishery Sciences, described his encouraging conclusions about the relative ecological impacts of land-based food production versus acquisition of edible protein and fats from wild seafood.
His interest was piqued when a colleague in Africa asked him whether he should stop eating sushi. As he told the Summit attendees, his answer was, “I don’t know … what’s your alternative [protein]?”
His friend said that since he was not a vegetarian, the probable alternative was to eat more meat and poultry.
That prompted Hilborn to calculate whether the eco and energy impacts of eating wild fish were greater or less than those associated with raising meats and poultry. He calculated that ocean fisheries have smaller environmental impacts and use less energy in comparison with meat and poultry, per pound of protein produced.
Hilborn pointed out that conventional livestock farms and the grain and soy farms that raise animal feed use lots of water, pesticides, and antibiotics, and cause soil erosion. Over time, he said, the natural systems that land-based agriculture uses become depleted, and the soil must be treated with synthetic petrochemical fertilizers to maintain productivity.
By contrast, he said, ocean fisheries require none of these inputs. (Of course, like the farm machinery used to raise the crops fed to livestock and to transport them, fishing boats burn fossil fuels.)
Hilborn stressed that the world’s growing population – and its growing appetite for meat – will increasingly impact the environment. So it matters how much edible protein you get for the amount of energy (typically fossil fuels) invested in production.
As Dr. Hilborn said, the “edible protein energy return on investment” or EROI* of 29 North Atlantic fisheries (9.5 percent) is much higher than any type of livestock (pork comes in at 5.6 percent; chicken, 2.9 percent; and beef, 1.9 percent).
And when it comes to greenhouse gas emissions related to all aspects of production, fisheries compare favorably with livestock, and far outperform beef cattle, which emit methane from both ends.
He calculated the tons of greenhouse gas (carbon dioxide) emitted per ton of “live weight” meat and poultry, versus major wild-harvest fisheries:
- Beef operations emit 11.3 to 18.3 tons.
- Pork operations emit 2.3 to 4.0 tons.
- Chicken operations emit 1.4 tons.
The only fishery comparable to chicken production was purse-seine tuna fishing, which emits 1.6 to 2.2 tons of carbon dioxide per ton of live weight.
Other fisheries emit far less carbon dioxide, with herring and sardine fisheries responsible for just 0.07 to 0.36 tons and Atlantic cod fisheries emitting 0.9 to 3.8 tons (average 2.3).
Professor Hilborn also noted that, compared with conventional livestock operations, ocean fisheries preserve many more ecosystem components and functions, including species diversity.
Even salmon farming – which involves chemical inputs and requires three pounds of fish to produce one pound of salmon – has less impact than production of meat and poultry, Hilborn added.
Last, he noted that neither land-based agriculture nor on-shore aquaculture (e.g., tilapia and shrimp farms) can meet a key standard used by the Marine Stewardship Council to assess sustainability:
“Fishing operations should allow for the maintenance of the structure, productivity, function and diversity of the ecosystem (including habitat and associated dependent and ecologically related species) on which the fishery depends.”
An obvious objection may be raised at this point, concerning pressure on wild seafood stocks, and the overfishing of some species and regions.
While this threat remains real and growing, Dr. Hilborn and Boris Worm, Ph.D. – scientists who’ve been on both sides of this debate – joined to produce a collaborative study that produce more hope for the future of wild fisheries: see “Sunnier Seafood Forecast Issued by Former Foes”.
When it comes to choosing animal protein, it seems clear that wild seafood is a better choice than conventionally raised meat or poultry (or farmed seafood), for eco reasons as well as health-related ones.
*Professor Hilborn calculated the EROI of various animal foods using a method devised by Peter Tyedmers, Ph.D., which, as he wrote, involves “dividing the amount of useful energy provided by a given activity by the culturally mediated energy dissipated in providing it. In the case of food production systems, a common energy output used to calculate the EROI is the edible protein energy yield from the system being evaluated.” (Tyedmers P. Fisheries and Energy Use, Encyclopedia of Energy, Volume 2, 2004)