farmed fish – getting the facts straight kevin fitzsimmons, ph.d. professor of environmental...
TRANSCRIPT
Farmed Fish – Getting the Facts Straight
Kevin Fitzsimmons, Ph.D.Professor of Environmental Science
University of Arizona, Department of Soil, Water, and Environmental Science
Tucson, Az
Feb. 19, 2009
OverviewFish and other seafood are universally
touted as highly nutritious and a key part of healthy eating
Some seafoods have been identified as contaminated or variable in nutritional values
Farmed seafoods have been reported to be more and less healthy than wild caught
Review of the science and consideration of benefits and risks
IntroductionSeafoods, and fish specifically, are
high in protein, minerals and vitaminsThe fats that are present, tend to be
polyunsaturated fatty acidsThe omega 3 fatty acids are especially
important
Remember organic chem?
Found in many marine algae, canola, walnuts, soybean, and flaxseeds
Essential part of the nutritional requirement of almost all organisms
Important in neural and cardiovascular functions
Facts about fatty acids in salmon Most farmed salmon
have slightly lower PUFA’s than wild salmon
However, the farmed product is still the next highest source of PUFA’s available
Moreover, farmers are rapidly adjusting feeds to increase omega 3’s
Facts about fatty acids in other farmed fish
Fatty acids can also be elevated in non-salmonid fish depending on feed ingredients
Higher omega-3’s are expensive and will likely require higher price
Tilapia - Moderate in PUFA’s: 0.387 g/100g raw
0.600 g/100g cooked Tilapia - Moderate omega 3 FA’s:
0.141 g/100g raw0.220 g/100g cooked
Source – USDA- ARS Lab
PCB’s in Salmon and other fish One study found higher PCB’s (which may
be a carcinogen) in Scottish farmed salmon compared to wild fish
Several subsequent studies found PCB’s in wild and farmed fish, but level was dependent on PCB’s in source water, wild prey fish or in fish feed
Level of PCB’s in all cases were minute and well inside “safe” levels and comparable to many other common foods
PCB risk vs. cardiovascular risk Risk and Benefits Levels in salmon vary from 0 to 30 ppb FDA level of concern is 2000 ppb (2ppm) EPA suggests that fish with 24 ppb or
greater should not be consumed more than once per month
Above 24 ppb increased potential for cancer may be 1 in 100,000
Comparison: Increased potential for cardio-vascular problems with high LDL’s is 1 in 2
PCB risk vs. cardiovascular risk Every technical report of PCB’s in salmon
has pointed out that heart benefits of salmon greatly outweigh cancer risks.
Fish feed companies now screen feed ingredients for PCB’s. And today’s supplies of farmed fish are now lower in PCB’s than most wild fish.
In Western US, most farmed salmon comes from southern Chile, which has little industry, very clean water and undetectable levels of PCB’s in salmon
Mercury in fish Methylmercury is a by product of coal
burning. It bio-accumulates in top predator fish in
freshwater and marine systems. In freshwater – Pike, muskies are problems In marine waters – sharks, swordfish and
tilefish are of concern for pregnant and nursing women and babies
Sources: EPA and FDAhttp://www.cfsan.fda.gov/~frf/sea-mehg.html
Mercury in fish EPA frequently publishes advisories to limit
consumption of wild freshwater fish Current advisories for several lakes in
Arizona, probably due to natural background levels in lakes
EPA advises to eat up to 2 meals of low mercury fish per week.
Farmed fishes have non-detectable levels, because they are grown in clean water and do not bio-accumulate from eating wild fish
The actual EPA Advisory Brochure
Examples: Shark (wild) = 0.99 ppm Tilapia (farmed) = N.D. to 0.01 ppm
Artificial color added Salmon and trout feeds sometimes include ingredients
that impart reddish or pink color to the flesh. Astanxanthin, canthaxanthin and beta-carotene are
commonly used. These may be plant or algae extracts, or chemically
derived. May also use whole algae as ingredient (Spirulina or
Dunaliella) Yes, the same extracts and algae sold in health food
stores, (which was not included in the scare stories)
Environmental concerns - Salmon
Some cage farms have contributed to benthic pollution in the past.
This is especially bad for the fish, so farmers rapidly moved cages to locations with more current and water flow.
Most new cages are in deep water.
New Cage Designs
Cages for warm water marine fishes
Environmental concerns with conventional
shrimp culture
Loss of mangroves and other coastal vegetation.
Integrated shrimp farming
Shrimp and SeaweedsGracilaria and shrimp production
in Hawaii
Shrimp and halophytes
Bivalve rearing – environmentally benign
Concerns with eating bivalves
Bioaccumulate toxins from algae bloomsNeurotoxic Shellfish PoisoningDiuretic Shellfish PoisoningVibrio cholera
Do not eat wild bivalves in months without “r”s
Farm raised bivalves are monitored and much safer
Aquaculture and fish farmingAquaculture is making huge advances in
productionDozens of species of plants and animals are
grown profitablyAquaculture products continue to provide more
seafoodAlmost all aquaculture is more sustainable than
commercial fishing
Aquaculture and commercial fishing
2005 UN-FAO reported 50% of all fish consumed globally were farmed
Most species are newly domesticatedNo by-catch or ship pollutionMuch safer for workers, fishing is US’s most
dangerous occupationFishing is last major “hunting and gathering”
lifestyle
Improved processing of farmed products
Competition with “wild” seafood:
US fishing industry complains about farm raised imports
Current tariffs on Norwegian salmon, Chinese crayfish, Vietnamese catfish, and shrimp from Brazil, China, Vietnam, Thailand and India
Wild fish have difficulty competing on price, quality and consistency
Future of farmed seafoodsCommercial fisheries will phase out in
favor of sport fishingFarmed products will account for vast
majority of seafood.Environmental sustainability is
increasing rapidly and will be achieved well before land farming.
Price and quality will continue to improve rapidly