Beyond = Salmon=20

Everything you ever wanted to know about buying and = cooking=20 fish (and other musing on all things yummy): by Helen = Rennie

Sunday, October 8

Parasites in Fish, Part 2 -- Anisakis and = Tapeworm

Now that we know all about cod=20 worms, we are going to venture in the world of the more dangerous = parasites:=20 anisakis simplex and tapeworm. If you are cooking fish, you need not = worry.=20 According to FDA, you are 100% safe if the fish reached an internal = temperature=20 of 140F. Surviving the human intestinal track isn=E2=80=99t easy and = requires that=20 anisakis and tapeworm be at full strength. So, if you = =E2=80=9Conly=E2=80=9D raise the internal=20 temperature to 120F, a parasite might survive (if he=E2=80=99s = positioned in the middle=20 of the fish fillet), but will be so weak that it will most likely die = shortly=20 after reaching your stomach.

Anisakis simplex is most common in = fresh=20 water and anadromous fish, like wild salmon, which are born in fresh = water,=20 migrate to the ocean, then return to fresh water to reproduce. It is = also common=20 in certain small salt water fish, such as herrings and sardines. = However,=20 anisakis is rare in other salt water fish, such as tuna, swordfish and=20 farm-raised salmon. Just like cod worm, it originates in seals. Tapeworm = is=20 mostly found in pacific wild salmon and fresh water fish. It originates = in bears=20 and land mammals. They are fascinating organisms and you can read all = about the=20 anisakis life = cycle and the=20 tapeworm life = cycle=20 on wikipedia.

Becoming a host to anisakis worms by eating them = live can=20 make you very sick---this disease is known as anisakiasis. According to = wikipedia, its = symptoms include=20 violent abdominal pain, nausea, and vomiting. "Occasionally the larvae = are=20 coughed up. If the larvae pass into the bowel, a severe eosinophilic=20 granulomatous response may also occur 1 to 2 weeks following infection, = causing=20 symptoms mimicking Crohn's disease." This isn't a life threatening = disease=20 (unless you have a weakened immune system) and is quite common in Japan = where=20 consumption of raw fish (that isn't previously frozen) is more wide = spread.=20 Unlike anisakis, tapeworms don't always manifest themselves with clear = symptoms=20 and can live in humans for decades if untreated, resulting in weight = loss,=20 Vitamin B12 deficiency, and potential anemia.

What used to bother = me is=20 the possibility of eating the eggs of these worms. Wouldn't they be too = small=20 for me to see, and what would happen if I eat them? Dr. = Palm, from the=20 Institute for Zoomorphology, Cell Biology and Parasitology in = D=C3=BCsseldorf,=20 Germany, put my worries to rest by explaining the life cycle of these = worms.=20 While anisakis and tapeworm are in fish, they are = in larvae=20 form (not egg form). They can't reproduce until they find a mammal host = (in the=20 case of anisakis and cod worm, it has to be a marine = mammal like a=20 seal, so they can't reproduce in a human), and tapeworms rarely = make it=20 into humans.

Are you ready to swear of sushi yet? Not so fast. If = you are=20 a US resident, keep in mind that you live in a country that just threw = away=20 every single bag of spinach because of E.Coli threat. You don't think = FDA would=20 allow anything remotely dangerous to be served to the US public, do you? = That's=20 why FDA requires all fish with a potential hazard of parasites that is = intended=20 for raw consumption to be previously = frozen.=20 Freezing fish to -20=C2=BAC [-4=C2=BAF] or below for 7 days or = -35=C2=BAC [-31=C2=BAF] or below for=20 15 hours will kill the parasites. Since the restaurants don't want to = take any=20 risk and want to avoid supply and demand price fluctuations, most go = even=20 further and freeze all fish (not only the ones that could be infected) = before=20 serving them raw. So, all that "fresh" sushi you've been eating is = previously=20 frozen.

What's counter-intuitive to most cooks is that = farm-raised salmon=20 is much safer to eat raw than wild salmon. Farm-raised salmon is served = pellet=20 food, which is ground-up, processed fish meat. Any parasites in the fish = meat=20 are killed in the processing and grinding stages. Since salmon only = obtains=20 dangerous to humans parasites via food, farm-raised salmon simply isn't = exposed=20 to them. So, next time you use salmon for gravlax, tartar, or sashimi, = go for=20 the farm-raised stuff. When the Food and Agriculture Organization of the = United=20 Nations tested various fish for parasites in 2003, no parasites were = found in=20 any farm-raised salmon species , whereas parasites were frequently found = in wild=20 salmon (section 5.1.4 of Huss et al., 2003).

Does salting fish = like for=20 gravlax or curing it in acid like for ceviche kill the parasites? Maybe. = The=20 salt or acid used for curing prevents bacteria from growing. It may also = weaken=20 or kill parasites. However, it=E2=80=99s not a full-proof method. = Opinions in the=20 scientific literature vary as to the degree to which salt/acid harms = parasites.=20 Most sources say that salting is more effective than curing in acid. = Also,=20 according to Dr. = Gardner from=20 Harold W. Manter Laboratory of Parasitology at the University of = Nebraska, the=20 acids in your stomach and intestines are at least as strong as = lemon/lime juice.=20 So, if you are making ceviche, I would suggest taking the same = precautions as=20 you would for eating the fish raw.

To put all this in = perspective, the=20 risk you take downhill skiing is an order of magnitude greater than the = risk of=20 eating raw, not previously frozen fish. Whether that risk is worth it is = up to=20 you. I hate downhill skiing and I love raw fish, so you can guess which = risks I=20 choose to take. In fact, the risk of driving or just walking down the = street is=20 probably higher than the risk of eating raw fish. I know plenty of = people who=20 were in life-threatening car accidents, and I am yet to meat a person = who got=20 infected by anisakis simplex or tapeworm. And let me tell you, I get way = more=20 pleasure from a bowl of sashimi than my morning commute.

Do=20 parasitologists eat sushi in spite of their intimate familiarity with = parasites?=20 Both Dr. Palm and Dr. Gardner said =E2=80=9Cyes=E2=80=9D. In fact, Dr. = Palm just got back from=20 Japan where he had really yummy not-previously-frozen = sashimi.

What does=20 all this mean to the home cook who wants to make sushi and ceviche? Buy = your=20 fish from a reputable source and use it that day if serving raw. = Regardless of=20 the parasite issue, fish that was not stored properly, or for too long, = will=20 grow bacteria and make you sick. Freezing fish that is not fresh will = not help=20 with the bacteria issue, but it will kill parasites. If you are not = planning to=20 freeze fish and want to eat it raw, I would limit your purchases to:

Large Tuna (Yellowfin/Ahi, Big-eye, Bluefin)
Farm-raised Altantic salmon
Scallops
Kampachi=20 (farm-raised)

If I find out about other fish that have = extremely low=20 occurance of parasites, I'll post them on Beyond Salmon.

What if = you want=20 to freeze your fish to eliminate even the slightest chance of getting = sick from=20 parasites? What=E2=80=99s the best way to freeze fish? Is all frozen = fish equal? Can you=20 buy frozen tuna from Trader Joe's, defrost it, and voila -- $5/Lb = sashimi is=20 served? In my next post, I'll answer all these questions and=20 more.

References:

H. H. Huss, L. Ababouch, L. Gram. Assessment = and=20 Management of Seafood Safety and Quality. 2003. Food and Agriculture = Organization of the United Nations. FAO Fisheries Technical Paper 444.

posted by Helen @ 4:15=20 PM 8=20 comments

8 Comments:

At 12:19=20 PM, Joe said...=20: What about the Monterey Bay Aquarium's recommendation to avoid farmed salmon?
=20
At 1:53=20 PM, Jason=20 said...=20: Hi Joe,

I'm Helen's husband. The trouble with the web page = you cite=20 is that it's lacking in details.

"Salmon farmers may use = pesticides and=20 antibiotics to control outbreaks of disease among the = fish."

Note the=20 use of the word "may." As written, this statement is basically = vacuous. If=20 you're worried about pesticides/antibiotics, ask your fishmonger. They = should=20 be able to tell you whether such chemicals were used in the raising of = Atlantic Salmon that you buy.

"The Environmental Defense has = issued a=20 health advisory for Farmed salmon due to high levels of PCBs and=20 dioxins."

Anyone can issue a health advisory. The page that = Monterey=20 Bay links to doesn't provide any details. Where are the scientific = studies=20 showing that if you eat Atlantic Salmon regularly, something bad will = happen=20 to you? I don't see any. If you know of any, please send them along, = I'd be=20 very interested to read them.

"Waste from most farms is = released=20 directly into the ocean. Parasites and diseases from farmed salmon can = spread=20 to wild fish swimming near the farms."

Any fish or mammal that = lives in=20 the ocean releases waste into the ocean. This waste can pass along = diseases=20 and parasites. A valid concern is that a Salmon farm could create an=20 unnaturally high concentration of waste. But, again, this depends on = the=20 farming company. Farmed Salmon are clearly better than wild Salmon in = one=20 respect: they don't transmit parasites that are dangerous to humans. = Table=20 5.21 from the Huss/Ababouch/Gram report shows that such parasites are = not=20 found in farmed salmon, whereas they are quite prevalent in wild = salmon.=20

Btw, all fish & mammals that live in and around the water = have the=20 potential to transmit parasites and diseases. It's misleading to say = that=20 farmed Salmon can infect wild fish, since if the Salmon had not been = farmed,=20 it would have also had the chance to infect (other) wild = fish.

"And=20 feeding farmed salmon actually uses more fish than it produces, which = puts=20 more pressure on wild populations."

This is also misleading. = The same=20 could be said about wild salmon---they eat more fish than they=20 produce.

"In the market, there is currently no way to tell = which salmon=20 are coming from more-sustainable farms..."

I doubt this is = true. I know=20 that Whole Foods is quite particular about their farm-raised Salmon. = While=20 it's probably true that many fishmongers won't be able to tell you the = details=20 of how their fish was raised, that's largely because consumers don't=20 ask.
=20
At 2:19=20 PM, Helen said...=20: Hi Joe,

Thanks for your question about farm-raised salmon. = It's an=20 issue that comes up over and over, and you've inspired me to do some = research=20 on the subject. There are two big questions: 1) does farm-raised = salmon pose=20 health risks? and 2) is it bad for the environment?

I have = some=20 information about the first issue. Here is an article from Tufts University School of Nutrition = Science and=20 Policy about PCBs in farm-raised salmon. At the moment, we have no = data that=20 PCBs in such small amounts are dangerous to your health. Here is my = previous=20 post on mercury in fish -- another hot button issue. =

As far=20 as antibiotics go -- Whole Foods label their fish clearly so that you = know=20 what you are buying, and they are starting to carry salmon without=20 antibiotics. But keep in mind that most of the meat that you eat was = treated=20 with antibiotics too. Is eating farm-raised salmon every day a good = idea? I=20 don't think eating anything in such access is a good idea. But there = is no=20 scientific evidence that eating farm-raised salmon is harmful to your=20 health.

From Monterey Bay Aquarium site: "When consumers eat = this fish,=20 the residues from the chemicals may affect their health or interfere = with=20 medicines they=E2=80=99re taking."

Some people are allergic to = seafood all=20 together. Does this mean we should consider it generally dangerous? =

I=20 haven't researched environmental issues yet. It's on my to-do list and = I'll=20 post about it as soon as I have some=20 information.

Cheers,
-Helen
=20
At 10:59=20 PM, Anonymous said...=20: Hi there,

Farmed Salmon have a VERY bad reputation = environmentally,=20 and farmed salmon may also possess significant health = risks.

Here's=20 some further information and some responses to your posts for further=20 consideration.

Jason stated:
>As written, this = statement=20 is
>basically vacuous. If you're >worried about pesticides=20 /
>antibiotics, ask your fishmonger.
>They should be able = to tell=20 you
>whether such chemicals were used
>in the raising of = Atlantic=20 Salmon
>that you buy.

Remember that the aquarium page is = not=20 providing an in-depth analysis of aquaculture. It is attempting to = provide a=20 summary of information that is widely available.

As for the = antibiotics=20 issue - there is very little chance that the average fishmonger is = going to=20 know if their fish is farmed or not. It is primarily specialty stores = that=20 spend the time to pay attention to that kind of food = issue.

Jason=20 stated:
>"The Environmental Defense has
>issued a = health=20 advisory for
>Farmed salmon due to high levels
>of PCBs = and=20 dioxins."
>Anyone can issue a health
>advisory. The page = that=20 Monterey
>Bay links to doesn't provide any
>details. Where = are the=20 scientific
>studies showing that if you eat
>Atlantic = Salmon=20 regularly,
>something bad will happen to you?
>I don't see = any. If=20 you know of
>any, please send them along, I'd
>be very = interested=20 to read them.

Health advisories are usually put out by agencies = that=20 have a duty to protect the public, so I think the comment that = "anyone" can=20 put out a health advisory is a bit weird. I can put out a health = advisory, but=20 no one is going to trust it! I would call the Monterey Bay Aquarium a = fairly=20 knowledgeable and trustworthy source!

Their stance is firmly = backed up=20 by the science. Here are some studies (out of hundreds available) = about=20 dioxins in farmed=20 = salmon:
http://www.albany.edu/ihe/salmonstudy/
http://www.newscient= ist.com/article.ns?id=3Ddn4547
http://www.news.cornell.edu/Chronicle/0= 4/1.15.04/salmon_health_risks.html
http://www.shns.com/shns/g_index2.c= fm?action=3Ddetail&pk=3DTOXICSALMON-01-08-04
http://www.medicalnew= stoday.com/medicalnews.php?newsid=3D24012

To=20 summarize the story told in these studies for you, the high levels of = dioxins=20 in farmed Salmon are a result of a process similar to bioconcentration = resulting from the food that the farmed Salmon are fed. Pellets fed to = farmed=20 salmon are impregnated with fish oil made from small fish. The oil = comes from=20 the part of the small fish's body where contaminants are concentrated. = Because=20 a small amount of oil comes out of each fish, farmed salmon end up = with a far=20 greater amount of dioxin than wild salmon - and a disproportionate = amount of=20 fish are killed, taxing the environment that these fish come from. But = because=20 the small fish are not valuable for human consumption, we feed them to = farmed=20 salmon, which ARE valuable for human consumption - ignoring the = environmental=20 impacts.

Jason stated:
>"Waste from most farms=20 is
>released directly into the ocean.
>Parasites and = diseases=20 from
>farmed salmon can spread to wild
>fish swimming near = the=20 farms."
>Any fish or mammal that lives in
>the ocean = releases=20 waste into the
>ocean. This waste can pass along
>diseases = and=20 parasites. A valid
>concern is that a Salmon farm
>could = create an=20 unnaturally high
>concentration of waste. But,
>again, = this=20 depends on the
>farming company.

Anti-aquaculture groups = object=20 to Salmon farming for many of the same reasons why factory farming is=20 objectionable. In a farm situation, the animals or fish and held in = large=20 numbers within a comparatively small area. Because the fish/animals = are so=20 concentrated it is very hard to keep the space clean (so the = fish/animals may=20 be sitting in their own waste - but this is of less concern in the = water) AND=20 because they are so concentrated any parasite/disease will travel very = quickly=20 through the population.

Salmon farms put lots of food = (overfeed) so=20 that their fish get big. Extra food is also added because the pellets = SINK -=20 so there is a lot of wastage.

Remember that Salmon farms are an = unnaturally large & dense population, so you get an exponentially = higher=20 level of parasites (captive breeding) and, bioconcentration, disease, = et=20 cetera.

This concentration of harmful factors would not be a = big=20 problem if it was dissipated by an ocean current, but most salmon = farms are=20 placed near streams and river mouths where salmon come to spawn. This = means=20 that more vulnerable members of the wild stock (like the baby salmon = aka=20 Salmon fry) are subjected to an unnaturally high concentration of = parasites -=20 so wild stocks become depleted.

This is why in factory farm=20 situations, like Salmon farms, the fish/animals are often given = antibiotics AS=20 A MATTER OF COURSE. That is to say, they are given drugs even if they = are not=20 sick, as a preventative measure.

Wild salmon don't have access = to the=20 antibiotics that farmed salmon are fed, so they are far more=20 vulnerable!

Jason stated:
>Farmed Salmon are = clearly=20 better >than wild Salmon in one respect:
>they don't transmit = parasites
>that are dangerous to humans.
>Table 5.21 from = the=20 >Huss/Ababouch/Gram report shows
>that such parasites are not = found
>in farmed salmon, whereas they
>are quite prevalent = in=20 wild
>salmon.
>Btw, all fish & mammals that = live
>in=20 and around the water have the
>potential to transmit=20 parasites
>and diseases. It's misleading to
>say that = farmed=20 Salmon can infect
>wild fish, since if the Salmon
>had not = been=20 farmed, it would
>have also had the chance to
>infect = (other) wild=20 fish.

Ask yourself this: why don=E2=80=99t the fish have = parasites? If wild=20 fish have the parasites, and the parasites occur naturally=E2=80=A6 = this must be=20 because the fish farms give their fish antibiotics. So you are trading = parasites for antibiotics in your food. Wild salmon have a lower = population=20 density, so they have less exposure to parasites... UNLESS they swim = near a=20 salmon farm.

Jason stated:
>"And feeding farmed=20 salmon
>actually uses more fish than it
>produces, which = puts=20 more
>pressure on wild populations."
>This is also = misleading. The=20 same
>could be said about wild salmon
>- they eat more = fish than=20 they
>produce.

This all goes back to the essential = problem with=20 all forms of factory farming:
- Farmed animals need to be fed=20 something
- The food that farmed animals are fed must be taken out = of the=20 environment, placing an additional stress that is not there=20 naturally

In this particular case, as previously stated, farmed = salmon=20 are fed food pellets flavoured with fish oil (they will not eat the = pellets=20 without the fish oil). The fish used to make the pellets are not = useful to=20 human, but that does not mean they don=E2=80=99t have a role to play = in the local=20 environment. Suddenly humans become a new predator, which impacts the = balance=20 of the overall ecosystem. If the food for the salmon was farmed as = well it=20 would be ISOLATED (somewhat) from the environment =E2=80=93 but they = are not, so there=20 is a direct impact.

A secondary effect of a fish-farm: highly=20 concentrated levels of decomposing matter in the local environment.=20 Decomposing matter is eaten by bacteria, which use up oxygen. Lack of = oxygen=20 kills plants in the local area (not enough air to breathe), and you = end up=20 with =E2=80=9Cdead zones=E2=80=9D downstream from fish farms. =

Jason=20 stated:
"In the market, there is currently no way to tell which = salmon=20 are coming from more-sustainable farms..."
>I doubt this is = true. I know=20 that
>Whole Foods is quite particular
>about their = farm-raised=20 Salmon.
>While it's probably true that
>many fishmongers = won't be=20 able to
>tell you the details of how their
>fish was = raised,=20 that's largely
>because consumers don't ask.

Totally = true! But=20 that's something people need to be educated about -they need to be = told that=20 they should ask. Or they can buy wild salmon and avoid the problem = (not there=20 are not problems with salmon fishing, there are environmental concerns = there=20 as well).

Helen stated:
>I have some information = about=20 the
>first issue. Here is an article
>from Tufts = University School=20 of
>Nutrition Science and Policy
>about PCBs in = farm-raised=20 salmon.
>At the moment, we have no data
>that PCBs in such = small=20 amounts
>are dangerous to your health.
>Here is my = previous post=20 on
>mercury in fish =E2=80=93 another hot >button issue. =

Again, a=20 great point! However, this must be mitigated by the fact that PCBs are = bioaccumulative. That is to say, PBCs NEVER leave your body and build = up over=20 your lifetime. Anything you can do to avoid PCBs is a good idea! The = higher=20 the concentration of contaminants in your body with free-chlorine (as = with=20 PCBs) the greater risk of cancer and many other health problems. PCBs = are an=20 issue with ALL seafood (and not an insignificant amount of other = food), but=20 are 20-30% higher in farmed salmon than in wild salmon. So if you = really like=20 to eat fish, you are better off with wild salmon.

Helen=20 stated:
>As far as antibiotics go -- Whole
>Foods = label their=20 fish clearly so
>that you know what you are
>buying, and = they are=20 starting to
>carry salmon without antibiotics.
>But keep = in mind=20 that most of the
>meat that you eat was treated
>with = antibiotics=20 too. Is eating
>farm-raised salmon every day a
>good idea? = I don't=20 think eating
>anything in such access is a good
>idea. = But there=20 is no scientific
>evidence that eating farm-raised
>salmon = is=20 harmful to your health.

There is real evidence that farm-raised = salmon=20 is harmful to your health (as has been shows above); however, it is a = matter=20 of long-term exposure and degree. The overall environmental impacts = may also=20 be a moral concern for some.

But you are right, aside from the = PCBs,=20 farmed salmon are no worse than any other farmed meat product in terms = of=20 antibiotics.

Helen stated:
"When consumers eat this = fish, the=20 residues from the chemicals may affect their health or interfere with=20 medicines they=E2=80=99re taking."
>Some people are allergic = to
>seafood=20 all together. Does this
>mean we should consider = it
>generally=20 dangerous?

No, but if something may contain nuts it has a = warning label=20 on it. Food with antibiotics which may interact with medications = should have a=20 warning label too, no? Just as products which "may contain fish" = should=20 probably have a warning label! :)

In any case, the point of all = his is=20 that there are real, significant, and important issues surrounding=20 aquaculture, and suggesting farmed fish over wild fish is a very = problematic=20 recommendation. Joe=E2=80=99s criticism is certainly legitimate, as I = have attempted=20 to show.

Maybe this subject deserves for a blog post? Give the = information to the people and let the people decide for=20 themselves!

Best of luck, your blog is = great!

-Steve
=20
At 11:12=20 PM, Helen said...=20: Hi Steve,

Ok, you've inspired me. I will research this issue = in=20 greater detail and will publish a post on farm-raised salmon. Just = give me a=20 few weeks :)

Cheers,
-Helen
=20
At 1:42=20 PM, Anonymous said...=20: I shall wait with bated breath!
=20
At 11:46=20 AM, Jason=20 said...=20: Hi Steve,

Thanks for the reply and thanks for the link to = the Hites=20 et al. study. I can see why you might be concerned---the headlines = certainly=20 make it sound like farm raised salmon is dangerous due to levels of = toxins=20 which are much higher than the levels found in wild salmon.

"As = for the=20 antibiotics issue - there is very little chance that the average = fishmonger is=20 going to know if their fish is farmed or not. It is primarily = specialty stores=20 that spend the time to pay attention to that kind of food = issue."

I=20 could be wrong, but I'm fairly certain that even mainstream grocery = stores in=20 the Boston area (where we live) specify farmed/wild. Though, I'd = certainly=20 agree with you that few fishmongers would know whether farmed fish = they sell=20 was exposed to antibiotics/pesticides/etc.

Concerning the = study: it is=20 clear from the study that farmed salmon have much higher levels of=20 PCBs/Dioxins/etc. than wild salmon. What isn't clear is whether these = levels=20 are sufficiently high to pose a danger. Also, the wild salmon on = average have=20 lower levels of omega-3's, so even if the PCB/Dioxin/etc. levels are = high=20 enough to pose a danger, the advantage of lower levels of = PCBs/Dioxins/etc.=20 might not be sufficient to offset the disadvantage of lower levels of=20 omega-3's.

Yes, researchers who published the original Jan 9, = 2004=20 Science paper have done later nutritional studies, e.g. J. A. Foran et = al.=20 "Quantitiative Analysis of the Benefits and Risks of Consuming Farmed = and Wild=20 Salmon". However, they do not provide evidence that wild salmon is = better for=20 you than farmed salmon. In particular, they do not study the change in = expected lifetime (or other measure of healthfullness) from switching = salmon=20 consumption from farmed to wild. Yes, wild salmon provides more = omega-3's "per=20 unit risk" (Figure 1). However, consumers don't eat food "per unit = risk." The=20 amount of salmon a consumer eats is unlikely to change in switching = from=20 farmed to wild. Also, the "unit risk" discussed by the authors seems = quite=20 small. They define unit cancerous risk as a 0.001% increase in the = risk of=20 death from cancer. If a consumer eats enough farmed salmon (purchased = from,=20 say, Eastern US retail locations) to achieve the recommended omega-3 = intake (1=20 g/day), he/she would face merely a 0.0125% increased risk of cancer = (due to=20 the PCBs/Dioxins/etc.) according to their calculations. This might be = more=20 than offset by the decreased risk of early death from coronary heart = disease=20 (versus eating wild salmon instead). They define unit non-cancerous = risk as=20 the U.S. EPA Reference Dose (RfD). The U.S. EPA RfD is "a scientific = estimate=20 of a daily exposure level that is not expected to cause adverse health = effects=20 in humans." I.e. it is a level many times lower than the level at = which=20 adverse health effects have ever been observed. Consumption of = sufficient=20 (Eastern US retail) farmed salmon to provide 1 g/day of omega-3's does = not=20 exceed the RfD.

"Anti-aquaculture groups object to Salmon = farming for=20 many of the same reasons why factory farming is objectionable. In a = farm=20 situation, the animals or fish and held in large numbers within a=20 comparatively small area. Because the fish/animals are so concentrated = it is=20 very hard to keep the space clean (so the fish/animals may be sitting = in their=20 own waste - but this is of less concern in the water) AND because they = are so=20 concentrated any parasite/disease will travel very quickly through the = population."

It sounds like this isn't so much a concern with = the=20 general idea of farming, but rather with farms which focus on lowering = costs=20 to the detriment of the environment and animal/fish health. = Personally, I'd=20 like to see designations for more environmentally-friendly fish = farming. It=20 seems that such designations on other products (e.g. "organic") have = helped=20 gradually improve the quality of farming in the U.S. via consumer=20 choice.

"Salmon farms put lots of food (overfeed) so that their = fish=20 get big. Extra food is also added because the pellets SINK - so there = is a lot=20 of wastage."

Do you know what is the typical degree of=20 wastage?

"This is why in factory farm situations, like Salmon = farms,=20 the fish/animals are often given antibiotics AS A MATTER OF COURSE. = That is to=20 say, they are given drugs even if they are not sick, as a preventative = measure."

Are you certain that all salmon farms use=20 antibiotics?

"Ask yourself this: why don't the fish have = parasites? If=20 wild fish have the parasites, and the parasites occur naturally... = this must=20 be because the fish farms give their fish antibiotics."

I think = you=20 missed my point. The main parasites which are dangerous to humans = (Table 5.21=20 from Huss/Ababouch/Gram) are transmitted via food. The grinding = process in=20 producing pellets for farmed salmon kills any such parasites = (antibiotics have=20 nothing to do with it).

"Decomposing matter is eaten by = bacteria, which=20 use up oxygen. Lack of oxygen kills plants in the local area (not = enough air=20 to breathe), and you end up with "dead zones" downstream from fish=20 farms."

Don't plants need CO2 to "breathe", not = O2?

"That is to=20 say, PBCs NEVER leave your body and build up over your lifetime. = Anything you=20 can do to avoid PCBs is a good idea!"

There is nothing you can = do to=20 completely eliminate exposure to PCBs. They can be found in most, if = not all,=20 foods. The important question isn't "how do I eliminate PCBs from my = diet?",=20 but rather "how do I avoid exposure to unsave levels of PCBs?" As far = as I can=20 tell, neither the original R. A. Hites (Science, 2004) study, nor = follow-up=20 studies indicate that farmed salmon have unsafe levels of = PCBs.

"There=20 is real evidence that farm-raised salmon is harmful to your health (as = has=20 been shows above); however, it is a matter of long-term exposure and=20 degree."

Why do you think so?

Anyway, I hope my comments = were=20 constructive. My goal isn't to push one angle or the other, but rather = to=20 understand the real underlying = concerns.

Cheers,

Jason
=20
At 3:47=20 PM, Anonymous said...=20: One concern that I think has not come up in this discussion is the=20 ecological consequences of farm-fish escapees. In areas where Atlantic = salmon=20 are farmed and are native (e.g., east coast of Canada, Maine, Norway) = there is=20 concern that farmed fish could escape, interbreed, or out-compete wild = populations of Atl salmon. Interbreeding farmed and wild fish can kind = of=20 "dumb down" the genetic make-up of wild populations.
However, on = the west=20 coast where Atl salmon are farmed (British Columbia and Washington), = this is=20 an introduced species. Our inland waters have been devasted by = introductions=20 of non-native fish. Many, many, many examples. There are all kinds of = concerns=20 when it comes to introduced species-- including passing diseases and=20 parasites, i.e., those normally only found in Atlantic fish, to our = native=20 fish.
There was also some talk about wastage/efficiency in food = that is fed=20 to farmed fish (with respect to lbs fed to lbs grown). I'm not sure if = this=20 was brought up, but one of the problems is that we're already = over-fishing=20 wild fish stocks. Catching even more fish to grind up for food only = compounds=20 the over-fishing problem.
Oh yeah... and wild fish just taste = better.=20 :)
Thanks for this forum.

Post=20 a Comment

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Sunday, October 8

Parasites in Fish, Part 2 -- Anisakis and = Tapeworm

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