Humane Treatment of Fish

[Sylvia Bernstein]

Every so often when I talk about aquaponics someone brings up issues around either the captive culture, or humane slaughter of fish.  These are important, relevant questions that we are going to need to wrestle with in aquaponics.

 

Here is a link to a short PETA editorial that just came out in our local paper about this subject.  Treehugger.com regularly brings this up.

How do you answer these questions?  Are fish humanely treated in aquaponics?  How do you humanely slaughter a fish?

[David R. Russell]

Rupert-

I am familiar with all of the above and have used all of the above at one point or another in various countries.  On transport- I have no issues with the use of clove oil (other than legality in the U.S.).  However, if it is being used at the time of slaughter (essentially at the time of processing) then there is no time for withdrawal as the fish is no longer alive to clear it (I think some of our differences on this is transport vs a tool for knocking out a fish for slaughter).  Granted if it is used for slaughter-the impact of any residues in the flesh would be negligable and of little concern from a health standpoint. Post slaughter, the fish should be well rinsed as one should anyway (especially in markets where people cook the whole fish rather than as a fillet).  The real health concern in regards to exposure is not from eating the fish- it is for the farmer or processor who gets clove oil containing water on them.  It is absorbed thru the skin and there could be health implications from repeated exposure.  (People intent on using clove oil should read a MSDS sheet for eugenol).

The active ingredient in clove oil, eugenol, comes in several forms.  One form, which is found in natural clove oil is the methyl form which is a suspected carcinogen.  Given the general concerns of food safety that most aquaponists have, I can't understand why one would use it.  There is a purified product form that contains just the good eugenol and not the suspected carcinogenic form (methyl eugenol).  If one is going to use it, may as well use the form that doesn't have any negative controversies associated with it.

RupertofOZ said:

The equivalent "approved" US product is "Finquel"....

 

And here's some "approved" methods ....

 

• Tricaine Methanesulfonate (TMS). This method is probably the most quoted by people with much experience in euthanizing fish humanely (i.e. for university experiments, etc.). TMS is also known as MS222 and commercially is known as Finquel. You can buy it from a pet supply store; Drs. Foster and Smith carry it; a bottle costs $24.99 plus shipping and handling. You can also buy this from PondRx ($14.99 plus shipping and handling for a 5 gram bottle) and Argent Labs. According to fish biologist Meyers' blog, simply by doubling the regular dose that you would use to anesthetize the fish will euthanize it. This substance is FDA approved for anesthetizing and euthanizing fish; it is the only product that is FDA approved to anesthetize fish.
• Benzocaine Hydrochloride is a drug requiring a veterinarian's prescription; you cannot buy it over the shelf for your fish. The AVMA advocates the use of Benzocaine hydrochloride but not straight Benzocaine. Benzocaine is not water soluble and must be mixed in water with acetone or ethanol, both can irritate fish tissue.
• Clove Oil/Vodka Method. Many fish keepers advocate using clove oil to anesthetize fish. You both anesthetize them first with the clover oil and dispatch the fish with another method or you give them such a strong concentration of clove oil that the clove oil alone will kill them. This article probably covers using the clove oil/vodka method is most detail: What is the Most Humane Way to Euthanize a Fish by wiseGeek.com. This process is not advocated by the AVMA in their 2000 report due to lack of research.

 

I've heard of the "vodka" method before... but it seems like a waste of perfectly good vodka to me...

[David R. Russell]

The Japanese have a device marketed for injecting high pressure air into fish brains.  It used for high end fish for sushi.  Highly effective, but the device scares me.

Carey Ma said:

We use a cone for chicken slaughter. How about fitting the fish in a cone and injection of compressed air to the brain? Or how about a water or light lazer-saw to zip their heads off (disconnect the vertebra)? Too fancy eh?

Thanks Rupert. You are always a wealth of information. I am so glad you support this site. I'd love to buy you dinner one of these days.

Cheers all.

[Carey Ma]

Smart idea that "car". 

Hmm, that's actually not much different from what the Chinese do except their fish aren't "cloved" before sorting which is a drawback but the fish are still manhandled which may be accepted practice but I still prefer avoiding handling at all unless absolutely necessary. 

I think they are onto something there with the close-able container (car). So if one panel can move, so can two. I'd modify that second panel to be a lift up bottom and a third panel to let the fish evacuate into the transport container via the auto sorting sluice I mentioned above.

Wah-Hee! Yahoo! Google me now! I think we just got something. Our new "car": no nets, no touch. Moved from lake/ pond to truck via displacement...I like it!

[RupertofOZ]

David R. Russell said:

Rupert-

However, if it is being used at the time of slaughter (essentially at the time of processing) then there is no time for withdrawal as the fish is no longer alive to clear it (I think some of our differences on this is transport vs a tool for knocking out a fish for slaughter).  Granted if it is used for slaughter-the impact of any residues in the flesh would be negligable and of little concern from a health standpoint. Post slaughter, the fish should be well rinsed as one should anyway (especially in markets where people cook the whole fish rather than as a fillet).  The real health concern in regards to exposure is not from eating the fish- it is for the farmer or processor who gets clove oil containing water on them.  It is absorbed thru the skin and there could be health implications from repeated exposure.  (People intent on using clove oil should read a MSDS sheet for eugenol).

The active ingredient in clove oil, eugenol, comes in several forms.  One form, which is found in natural clove oil is the methyl form which is a suspected carcinogen.  Given the general concerns of food safety that most aquaponists have, I can't understand why one would use it.  There is a purified product form that contains just the good eugenol and not the suspected carcinogenic form (methyl eugenol).  If one is going to use it, may as well use the form that doesn't have any negative controversies associated with it.

 

Agreed David... the possibility for uptake into the flesh when slaughtered is negligable... and standard washing procedures should result in nil tainting...

 

Agreed also, that standard care and procedures need to be taken by the operator when using clove oil, or any "chemical"...

 

But again... the amount generally used is miniscule.... and usually either measured... or dripped until effective...

 

Whilst it's possible... an operator would need to be pretty sloopy to get any on themselves.. and if they did should immediately wash thoroughly....

 

And yep, using the "non-harmful" (supposedly) endorsed product is to be recommended.... but the cost is significantly greater....

 

And like all chemicals that "might" be used, or have a use... in aquaponics... I wouldn't advise anyone doing so unless they knew what they're using, it's possible effects.. and how to use it...

 

But the post was more directed towards Carey's question relating to grading/harvesting/transporting of pond based, or larger quantities of fish... to minimise handling stress...

[Shas Cho]

I'd like to offer a counter argument

to those who object to raising fish for food:

 

While it is true that our fish are raised in an artificial environment,

it takes only a bit of open-minded observation to see

that with good care, these fish are not stressed or unhappy

(and is is easy to see when they are unhappy-

just watch an angel fish

whose long-term partner has died or has been removed).

They go about their business

looking for food, squabbling, interacting,

choosing mates and raising babies.

 

More importantly,

by raising fish and vegetables aquaponically

we are the people who are striving

to reduce our burden on this planet.

We reduce transportation and processing

(hence carbon and electrical production),

we reduce the amount of water used to grow our food,

we reduce offshore fishing,

and in general our actions support more humane treatment

of ALL creatures great and small.

 

Aquaponics is better for animal welfare worldwide

than flying helicopters and zooming around in hi-speed boats

making animal welfare movies.

 

Or so I see it.

I am proud to promote aquaponics.

[TCLynx]

+1 Shas I agree.

[Rob Nash]

i say thak you for your sacrafice, and whack em between the eyes 3 times real quick. then put him into the ice water.

when i throw mine into the ice water alive, they kick around for a good minute or three...didnt feel good to me.

i like to put them into the ice water to drop the temp of the fish down to 40 or so. like TC said, you may want to use a glove, the fish are cold and hard to hold onto.

[Jon Parr]

I think the issue and the question has been well answered with good variety. The only question that remains is how should one humanely dispatch a PETA activist? That's a lot of ice-water, and an insufficient blow to the head may lead to countermeasures by the activist. I like the idea of purging the activist in frigid saltwater for 3-5 days, followed be electrocution. That is the most humane, and probably the way the activist would have wanted it. :)

[Kellen Weissenbach]

Ha!  You're evil Jon. :)

[RupertofOZ]

Jon Parr said:

 I like the idea of purging the activist in frigid saltwater for 3-5 days, followed be electrocution. That is the most humane, and probably the way the activist would have wanted it.

 

So rather than trying to sail in front of the Japanese whaling boats.... the Sea Shepard should just throw the PETA activists onto the whales... allow the Japanese to harpoon them, haul them aboard.... and then electrocute them....

All in the name of science... of course...

[Gina Cavaliero]

I do agree that PETA takes an extremist stance, however in order to gain publicity and recognition often that is what you do.  No one would pay much attention otherwise, so really it is more just an incredibly aggressive, in your face type of marketing campaign and likely it is very necessary when it comes to animal rights.  They cannot defend themselves and unfortunately some humans have little regard for being humane, so it does take extremists to actually be effective.  

I actually found the article horrific.  Why would a facility have that type of practice?  Surely working on a live, wriggling fish can't be easier then processing one that is not fighting back!  The reality likely is that a costly step was eliminated.  So, when humans cannot make a humane, ethical decision in lieu of profits, then activists are needed to expose that type of behavior and I agree that exposure needs to be in your face.  As TC pointed out, the general population is far removed from how their food reaches their plate and have little thought to how that animal was treated as they shove it in their mouths.  Without groups like PETA most would just keep shoveling while animals suffer.

Kellen, I have to strongly disagree with your logic.  How can you equate the horrible violent deaths that animals experience in the wild to mistreatment by humans?  That's like saying just because we have larger more complex brains and opposable thumbs that makes it all ok.   Ha!  Silly animal, you are lucky that you are not going to be eaten by a bigger fish in the wild, we are going to raise you in confinement with tons of others of you and then skin you alive.  I'm betting given a choice, they'd take their chances in the wild.  Animals in the wild are just that, wild and the way they meet their demise is natural, albeit often violently, but that is nature.  The way factory farmed animals meet theirs is not and as a supposably humane creature with the larger brain, we have a responsibility to insure that animal is treated and killed humanely.  

As TC pointed out, is any way truly humane?  The simple reality is no, there is nothing humane in ending an animal's life, unless you are relieving them of some kind of suffering.  The other simple reality is that most humans are omnivores and will eat the slower or less intelligent of earth's inhabitants, however there is a responsibility to do that in the most humane way possible.

As to how we have killed fish, we either club or do icebaths and really clubbing seems to be the quicker or more "humane" of the two.  Many of the fish suddenly exposed to the icey water, thrash around quite a bit.  I would think the initial shock is not pleasant but then the nature of the ice water is quickly numbing, so they probably don't feel anything soon, but there was that initial shock, possibly endorphins released and that is something not desirable in a fresh kill anyway.  As to a purge and allowing them to slowly demise over five days before they are finally killed, on the eating side, sorry, but eeew!  Unless you are running super high densities and water quality is compromised, I don't see the necessity for a purge anyway.  With clean, balanced system water from a healthy ecosystem, what is there to purge, unless you are just doing to clear the gut and that can be done by simply not feeding for a few days.  The whole purge theory is far more about the eating then the killing.  

[Rob Nash]

i have done a side by side purge test and cant tell any difference. after not feeding for 4 days, they taste just like the one that was eating when i pulled him out.

ive noticed that when whacking a fish in the face, its better to do it 2 or 3 times real quick. you can feel him tense up at the first one and relax by the third one. i really think it makes a difference, ...some times i notice one or two of them are stiff like they have rigor mortis, while the others are nice and loose, this is after just 15-20 mins, while filleting. so now that i try to whack him till he relaxes, none of them are stiff when i fillet them.

For me, this covers the "fastest way to kill a fish" and the "best food preparation" side of things.