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?

[TCLynx]

I don't think the cold or salt are particularly bad for trout.  However very sudden changes in temperature are generally very detrimental to most fish so suddenly going from say 70 F water into ice with just enough water to be able to submerge the fish, will likely send most any fish into a basically unconscious (or at least inactive) state within a few minutes.  I can tell you that it doesn't kill catfish at least not quickly to submerge them in ice water the way it will kill tilapia.

[Myles Harston]

A lot of thoughtful responses.   Thank you all.. At AquaRanch we purge for 3-5 days by with holding food.  We do not drop the temp when  we purge.  I want the gut empty and if the temperature is dropped the gut slows down.  Fish can go a lot longer than a mammal without food without adverse effects.   We use a very cold ice water bath.   The temp shock from 75-80 degrees to below 30 degrees is a bigger shock than from 60 degrees to below 30 degrees,  and we have found they will transpire faster.   We have also found that the fish are easier  to fillet when they are properly chilled.   Also there is less blood in the fillet because the blood flows to the core of the fish.

[TCLynx]

Yes my mom did note that the chilled tilapia were easier to fillet than the ones simply netted and konked on the head.

[Matthew]

I very much want to get started in Aquaponics, and one road block has been I have had pet goldfish.  I could never kill anything that looked like them. Going to get bullhead catfish in hopes they will look nasty enough, and I will not be watching them through a glass aquarium and getting attached to them.  I am sure I will struggle a lot when the time comes for harvest, but I guess I will have to tough through it.  I will thank the fish as did the native Americans did their kills.  Hoping a quick ice bath and then the knife to cut their spine will be quick.  To justify it mentally, if I bought fish at the store, someone killed it...

[Myles Harston]

Matthew said:

I very much want to get started in Aquaponics, and one road block has been I have had pet goldfish.  I could never kill anything that looked like them. Going to get bullhead catfish in hopes they will look nasty enough, and I will not be watching them through a glass aquarium and getting attached to them.  I am sure I will struggle a lot when the time comes for harvest, but I guess I will have to tough through it.  I will thank the fish as did the native Americans did their kills.  Hoping a quick ice bath and then the knife to cut their spine will be quick.  To justify it mentally, if I bought fish at the store, someone killed it...

Matthew,   You don't have to eat them if you grow Koi for ornemental pond stocking.   As far as Bullhead,  an old friend of mine in Wisconsin has found a way to make them palatible.   He puts them in a smoker.  I am afraid that is the only way I could eat them.   ;o)   He even gets a premium price for the smoked fish,  about 6 bucks a pound, gutted.

[Jon Baldwin]

I was always taught that fish have an "icky" or "icky spot" - not a joke, it's essentially the place behind the eye where their tiny brain is. When you prep fish, you "stick 'em in the icky" (stab cleanly through the brain) then throw them into an ice and salt slurry to chill them quickly.

They die quickly without releasing bad-tasting chemicals into their blood stream. The fish "firms up" in the sub-freezing slurry. The cold keeps them very fresh and and makes the butchering process a bit easier and cleaner.

Any of us who eat any meat yet complain about the treatment of animals are hypocrites. We're just "executing by proxy" and enjoying the spoils.

Just a PS on the PETA comment on fatty acids and cholesterol: watch the movie "Fat Head" to learn more about the lipid myth.

[TCLynx]

give em as great a life as you can and kill as quickly and cleanly as possible.  That is about the best we can hope for.

 

And even veggies firm up if you dip them in ice water right after harvesting most of them.

[Jesse Hull]

I don't know how I missed this, Sylvia.  I believe this was one of my questions to you at the end of your presentation at Sweet Water in January, but this discussion just slipped past me (my other question regarded responsibly dealing with cumulative bio-solids once collected from clarifiers, etc, which I did create a discussion for on this forum). 

At Sweet Water, we move graded fish into one of the 600gallon tiered aquaponic systems for a few days prior to harvesting.  I designed clarifiers and screen filters for these smaller systems similar to the larger ones I built for the 9,000gallon systems, although water exchanges are also employed to keep the water in these holding tanks as clean as possible.  After 2-3 days, the harvested fish are placed immediately in a 30/70 mix of ice cubes and water. Only a small number of fish are harvested  -never more than can be dealt with in a couple hours (typically about 500 fish).  After residing in the ice water for 20 minutes, fish are bagged placed in bins filled with fresh ice and sent to the processing facility.

I believe that the catching and transfer of the fish in a humane manner is just as important as euthanizing them.  Since our larger raceways can be awkward to work around, Matt Ray and I designed a "cage" that is set on the bottom of the tank (Matt did most of the work in actually creating the cage). Fish are attracted to the area by a small amount of food, and the cage is brought up from underneath them.

It needs to be built beyond the current prototype, but the intention is that the bars of the cage be spaced just far enough apart to grade the fish by allowing most of the smaller ones to pass back into the tank as it is brought up.  The larger fish are then carefully poured into a water basin on wheels, which can be rolled over to the above mentioned 600gallon tank to be measured and counted during the final transfer.  During the entire process, no fish are kept in the open air any longer than we could comfortably hold our own breath. 

We just performed this process successfully today, culling over 300 Yellow Perch and 100 Tilapia in five 15 minute sessions. 

[Johann]

Ice water should take only seconds.

Years back I had minnows sitting in a 5 gallon pail outside and the top 1/2 inch got iced up since it was so cold.

 

I got cold water from the kitchen faucet and put it in a different pail. I then broke the ice and caught all the minnows with a net from the cold water. I put the minnows in the cold "warm" water from the kitchen faucet and they all died in 2 seconds. By the time I even saw that there was a problem they where all dead.

I don't think it matters which way you go, from warm to cold or cold to hot, what matters is that there should be a lot of temperature difference so they do not suffer. 
Kobus Jooste said:

Well, as I said, I'm not sure how long the ice will take but at least it will be consistant in effect.  If you feel sorry for the fish or your aim is bad you may fluff the priest method and then you may just rue trying it (or tonk it to the promised land second time round)

Sylvia Bernstein said:

Joel Salatin is also featured prominently in Michael Pollen's "Omnivores Dilemma".

 

You all have made great points, as usual.  Kellen, I actually laughed out loud at the notion of PETA protesting lions!  

 

I've been asked a few times, probably because I live in Boulder , about the "happiness"  of the tilapia in my tank.  My response usually has to do with them being in pure, aerated water and being a schooling fish.  But what are your thoughts?

 

And is smacking a tilapia on the head the best way to kill them, or is putting them in an ice bath better?

[Munkh-Ochir Jamsran]

Fish has a small body, so I think putting them in a salted water fish purging tank and electrocute them with 220 Volts will do. Haven't tried it yet but thinking about it as I'm intending to farm fish commercially. It's instant and fish will never know what hit them. Actually they may get relieved from the scared state they were from all the netting and fishing and getting into a damn salty water. :D

 

Just my thought

 

May all the fish souls rest in peace...

[Harold Sukhbir]

Hi Munkh,

This one is good! In the wild scientist stun fish with electricity, they float to the surface and remain unconscious for several minutes, in this state they can be slaughtered without any feeling on their part.

[Alfio Contarino]

Are fish humanely treated in aquaponics?

Personally I don’t  believe so.  I come from an aquarium background, where it’s all about the water AND the environment.  In an aquarium the water conditions are monitored like in aquaponics, but the environment is always over looked.  In my system in the fish tank area I have gravel at the bottom, rocks and plastic plants arranged so there are areas for fish to hide and swim through and around.  I also have the tank covered as most fish prefer privacy and do not live near the surface where the direct sun light is.   I believe that if the environment and water conditions are right the fish will be happier and stress free..  Stress is a big killer of fish... 

 

After all fish do not live in an empty container in nature....