Farming Fish

[Sandison]

I can't, with respect, accept the 1:1 figure because I have never seen any indpendent verification of it. Even if it were true, what is the point of using one tonne wild fish to produce one tonne of fake fish?

 

On artificial stocking of rivers, my view is that to do so is a sign of failure. Management and habitat improvement is the key to a river's health.

 

Bruce Sandison

[Ian Burrett]

These are the chemicals found in Organically Farmed Salmon

 

One should take such claims cum grano. Colourants to pink its flesh; x-rays for sterilisation; hormones to eradicate sex-drive; sprayed with medicament, insecticide and pesticide; dosed with antibiotics; imprisoned in densely packed cages; vaccinated; genetically manipulated… hardly an “organic” regimen. Neither are many of the constituents of the farmed salmon diet:

 

NUTRIENTS MINERALS/CHEMICALS

 

White fish Flesh dye (Canthaxanthin)

Blood meal Magnesium sulphate

Hydrolised feathers Iron oxide

Meat bone meal Zinc sulphate

Cane molasses Potassium iodide

Fish oils Sodium carbonate

Soya Zinc oxide

Antioxidants Di-calcium phosphate

Yeast Copper carbonate

Herring offal Cobalt sulphate

Saithe offal Cobalt carbonate

Binders (cellulose, alginate) Optional; antibiotic

[jabee]

NUTRIENTS MINERALS/CHEMICALS

 

White fish Flesh dye (Canthaxanthin)

Blood meal Magnesium sulphate

Hydrolised feathers Iron oxide

Meat bone meal Zinc sulphate

Cane molasses Potassium iodide

Fish oils Sodium carbonate

Soya Zinc oxide

Antioxidants Di-calcium phosphate

Yeast Copper carbonate

Herring offal Cobalt sulphate

Saithe offal Cobalt carbonate

Binders (cellulose, alginate) Optional; antibiotic

 

 

Mmmmm, tasty

[JB]

Jaffa

“They say it takes 5 tons of feed fish to raise 1 ton of farmed fish. If that is true, would it be a reasonable assumption to say that the same 5 tons of feed fish would also raise 1 ton of wild fish?”

 

As I understand it no; for wild fish it would be more like 10 to 12 tonnes. Farmed fish don't have to expend energy on foraging for food, avoiding predators, breeding etc.

 

That said, the diet of eg a wild cod will consist of a lot more variety than just "industrial fish".

Hi, Chris.

Thanks for putting me right on the first point. I had a feeling it was more than 5 tons but had no easy way of finding out.

 

I realize that the diet of cod is very varied. I have taken many a plastic cup and white pebble out of a cod’s stomach. And I know someone who found a cassette tape in a cod’s stomach, and it still played. (It was not Des O’Connor, though.) We have also found over the years that they are very partial to rubber, plastic and painted pieces of lead.

 

I remember reading somewhere that sandeel made up 40% of a North Sea cod’s diet. This sounds very high to me, but I do believe it is a very important part of their diet. Maybe you can help on that one.

 

We fish over a large area of the North Sea. It seems the only way to keep up good regular catches these days is to ensure that no single area gets too much hammer. Like most types of fishing, we don’t fill up every trip, but we do keep up a good average catch. Our area of operation varies between 53 and 57 degrees North and off to 4 degrees East, in places. According to my GPS we have moved over 100,000 miles in the last six summers, so I can safely say we get about a bit. I know most of the very few remaining British fishermen that work these same offshore grounds. We have all come to the similar conclusion that the cod’s diet is made up of far less industrial fish than it used to be.In years gone by we used to catch large quantities of cod full of and/or spewing up feed fish. Now only a very small percentage of our fish do this.

 

This year we have seen a very large number of tiny dover soles in the stomachs of cod, so the lack of normal food must be putting some pressure on other stocks. But if we had a sole shortage it would not be the cod’s fault - Wurzel would get the blame for catching them all!

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Loch Awe Pike,

Well i would just like to give a fish farmers point of veiw on the subject of feed. I hear all the time of quotes that it takes between 3 and five ton of fish meal to produce 1 ton of salmon. in my experiance as a fish farmer (which is 15 years)i think that it would be impossible to feed salmon 5 ton of feed and receive only one ton growth. we have a system that monitors how much feed we use, and it involves a simple calculation which is Total feed fed divided by total weight gained this gives you a feed conversion ratio. In my line of work the target of this feed coversion ratio is 1.1 to 1 now that spelled out is 1.1 ton of fish feed to produce 1 ton of salmon. now i dont think that is unreasonable do any of you?

 

Now i am also a very keen angler i also have an interest in wild fish stocks also.and the reason i belive that nothing is done about replenishing wild stocks is MONEY! who is going to pay for it? and who is supposed to pay for it?

The technology is available today its just no one will foot the bill to get it going. The answer is that fish reared for the wild are returned to the wild before they reach the stage that they require an artificial diet and allowed to fend for them selves. It then is just a case of numbers which is why fish lay down so many eggs in the wild. But hatchery techniques today can improve survival rates of eggs by first of all improving the fertilization at stripping then by good husbandry while they are incubating.

Once the fish hatch they should be returned to their natural environment to fend for themselves let instinct take its course. this needs to be continued until the fish stocks are healthy enough to sustaine them selves while still under commercial pressure.

I could keep going but i wont but i will say that its nice to know that people are thinking about and that every comment made shows that thought has gone into this subject.

they say that fishermen are the worst fish farmers because they expect perfection every time.

Hi Loch Awe Pike,

First of all I know absolutely nothing about fish farming, So it’s nice to have your experience and point of view. A few questions, if you don’t mind?

 

What is the rough make-up of the feed that you give to your fish? It obviously contains dried fish meal and oil. Do you know how much water is extracted from the live fish weight to make it into a part of the feed that you use? (I know that depending on the fish, fish is made up of 70 to 80% water.)

 

How do you see the future of fish farming? Again, I have read that it is a very fast- growing industry. If this is so, do you think it would put too much demand for fish meal and fish oil on our already over-pressured seas?

 

Do you know of any other sources, or proposed sources, for food for your fish product?

 

With the present North Sea sandeel ban, has this put your fish food bills up? If not, what is the origin of your fish food product?

 

I have long thought that replenishing the seas stocks was a very good idea. I am glad to hear from you that the restocking of our seas is achievable. However, over the past few years I have pondering as to whether or not it would do any good. There has been much talk on this forum about sustainable fishing. But I can’t help wondering, under present conditions, how much fish the sea can actually sustain. I am of the opinion that restocking the part of the North Sea that I fish in, say with newly-hatched cod, would just create a little more food for the already starving bigger fish.

 

 

Sorry about all the questions!

JOHN BRENNAN

Edited October 24, 2005 by John and Michele

[loch awe pike]

I can't, with respect, accept the 1:1 figure because I have never seen any indpendent verification of it. Even if it were true, what is the point of using one tonne wild fish to produce one tonne of fake fish?

 

On artificial stocking of rivers, my view is that to do so is a sign of failure. Management and habitat improvement is the key to a river's health.

 

Bruce Sandison

Well the figures i used are the ones that i was taught at college and the ones in which i try to achive personnely my piont was to say that not all salmon farmers go about their day without concideration for the environment or care for the fish we rear. I take pride in my work and do all that i can to ensure that i have healthy good quality fish and that what do has the bare minimum impact on the environment.

Also i agree that habitat improvement is the key to a rivers health but i fear that time is already running out for some stocks of wild fish and that failure is what we are faced with. Also i am not for one min suggesting that rivers be stocked with farmed fish as to get to that stage would be worse than failure as to loose the original stock in the first place would be a crime to nature. but like i said if you can improve the fertility rate and increase survival to the piont of hatch then surely that has to be one option that cant be dissmissed.

[Sandison]

Well the figures i used are the ones that i was taught at college and the ones in which i try to achive personnely my piont was to say that not all salmon farmers go about their day without concideration for the environment or care for the fish we rear. I take pride in my work and do all that i can to ensure that i have healthy good quality fish and that what do has the bare minimum impact on the environment.

Also i agree that habitat improvement is the key to a rivers health but i fear that time is already running out for some stocks of wild fish and that failure is what we are faced with. Also i am not for one min suggesting that rivers be stocked with farmed fish as to get to that stage would be worse than failure as to loose the original stock in the first place would be a crime to nature. but like i said if you can improve the fertility rate and increase survival to the piont of hatch then surely that has to be one option that cant be dissmissed.

[Ian Burrett]

Hi John

The official figure is 3.5 tons of fish to provide 1 ton of fish pellets

[Sandison]

Thanks for that response, and I am sure that you do exactly what you say you do and try to produce the best farm fish that you can.

 

My primary concern is that wild salmonid stocks in the West Higlands and Islands of Scotland are being driven to extinction by the impact of fish farm disease and pollution, particularly by sea lice from these farms.

 

To save our wild fish, and to protect our marine and freshwater environment, these farms have to be removed from our coastal and freshwater lochs.

 

If it is possible and profitable to farm barramundi in the New Forest (Aquabella Plc) and tilapia near Ely in Cambridgeshire (UK Tilapia Ltd), then there is no reason why salmon should not be reared in the same way.

 

Bruce Sandison

[loch awe pike]

Jaffa

 

Hi, Chris.

Thanks for putting me right on the first point. I had a feeling it was more than 5 tons but had no easy way of finding out.

 

I realize that the diet of cod is very varied. I have taken many a plastic cup and white pebble out of a cod’s stomach. And I know someone who found a cassette tape in a cod’s stomach, and it still played. (It was not Des O’Connor, though.) We have also found over the years that they are very partial to rubber, plastic and painted pieces of lead.

 

I remember reading somewhere that sandeel made up 40% of a North Sea cod’s diet. This sounds very high to me, but I do believe it is a very important part of their diet. Maybe you can help on that one.

 

We fish over a large area of the North Sea. It seems the only way to keep up good regular catches these days is to ensure that no single area gets too much hammer. Like most types of fishing, we don’t fill up every trip, but we do keep up a good average catch. Our area of operation varies between 53 and 57 degrees North and off to 4 degrees East, in places. According to my GPS we have moved over 100,000 miles in the last six summers, so I can safely say we get about a bit. I know most of the very few remaining British fishermen that work these same offshore grounds. We have all come to the similar conclusion that the cod’s diet is made up of far less industrial fish than it used to be.In years gone by we used to catch large quantities of cod full of and/or spewing up feed fish. Now only a very small percentage of our fish do this.

 

This year we have seen a very large number of tiny dover soles in the stomachs of cod, so the lack of normal food must be putting some pressure on other stocks. But if we had a sole shortage it would not be the cod’s fault - Wurzel would get the blame for catching them all!

-----------------------------------------------------------------------------------------------

Loch Awe Pike,

 

Hi Loch Awe Pike,

First of all I know absolutely nothing about fish farming, So it’s nice to have your experience and point of view. A few questions, if you don’t mind?

 

What is the rough make-up of the feed that you give to your fish? It obviously contains dried fish meal and oil. Do you know how much water is extracted from the live fish weight to make it into a part of the feed that you use? (I know that depending on the fish, fish is made up of 70 to 80% water.)

 

How do you see the future of fish farming? Again, I have read that it is a very fast- growing industry. If this is so, do you think it would put too much demand for fish meal and fish oil on our already over-pressured seas?

 

Do you know of any other sources, or proposed sources, for food for your fish product?

 

With the present North Sea sandeel ban, has this put your fish food bills up? If not, what is the origin of your fish food product?

 

I have long thought that replenishing the seas stocks was a very good idea. I am glad to hear from you that the restocking of our seas is achievable. However, over the past few years I have pondering as to whether or not it would do any good. There has been much talk on this forum about sustainable fishing. But I can’t help wondering, under present conditions, how much fish the sea can actually sustain. I am of the opinion that restocking the part of the North Sea that I fish in, say with newly-hatched cod, would just create a little more food for the already starving bigger fish.

Sorry about all the questions!

JOHN BRENNAN

Hi John i appreciate the manner in which you address this subject as it is fair to say that it is a subject of interest to many including myself. i will if possible answer all of your questions if i cannot i will find out for you and answer at a later date if that is ok.

There is reasearch ongoing i think into the use of vegatable proteins to replace or partially replace fish proteins. however i belive that in the fresh water stages of growth that an invertebrate or similar thinking along these lines this bneing my personnel veiw.

As for what the diet is made up of it usually consists of between 45% to 60% of protein 20% to 30% between 20% to 30% ash then the rest is made up of carbohydrates fibre and phosphorus.

The fish used varies a bit details of which i am not 100% of but if you are interested i can find out. and yes feed bills are on the increase.

As for the question of how i see fish farming in say 20 or so years well i would like to think that will still be here and i hope thriving as fish are a good nutritional meal for any one, but as we hear every week that sea stocks are being over fished and that fish stocks are declining.

I dont pretend for one min that its perfect but will say that salmon farming as an industry is only 30 years old so still in its infancy, but farming fish is as old as the hills. It just needs to find the right way to see it into the future.So to answer your question about the future of fish farming? well depends which species you farm who knows?

As for the restocking of our seas well i dont know much about cod and would need some help to first of all to understand a cods natural life cycle but i feel that it is the fish lower down the food chain ie sand eels that need the attention as they are the key to most predatory fish,birds,whales and dolphin and not forgetting man. But its a sad day when even the humble mackerel is far less common than once apon a time in the not to distant past.

I hope this has helped in some way John and would gladly go on discussing these issues furthur. I dont have all the answers but do care enough to at least explore possibilities and try and come up with some answers.

[JB]

Hi John

The official figure is 3.5 tons of fish to provide 1 ton of fish pellets

Hi Ian, thanks for the info.

 

It takes 3.5 tonnes of wild feed to produce 1 tonne of dried fish food, and 1.1 tonnes of food to produce 1 tonne of salmon. Let us assume cod need the same amount of feed as salmon. If this cod farm in the Shetlands is to produce 15,000 tonnes per year by 2010, they will need 3.5 x 1.1 x 15,000 = 57,750 tonnes of wild feed fish per year to support 1 cod farm in the Shetlands. And there are other cod farms already planned.

 

Loch Awe Pike, would you agree with this calculation?