Study: Trophic Interactions and Consumption of Wild Fish and Plankton by Cage Reared Salmon in BC

[Birdsnest]

I'm posting this separately with the hopes that the topic can remain the centre of the discussion but there is no doubt that some will have difficulty with that and continue to deflect from topics by dismissing participants contributions by using terms such a "PR Machine", "Industry representatives" etc.

Lets just have a discussion and not a competition.


Anyway, here it is:

http://www.dfo-mpo.gc.ca/Library/322459.pdf

From the paper:

"Our main conclusions are that the “individual” cage-reared salmon consume few number of wild fish or plankton. Given the results examined, we were unable to extrapolate the potential impact from the entire “population” of cage-reared fish on wild prey. We found that the most common wild organisms consumed were caprellids, which live on the side of net pen cages. We found few fish in the gut samples, most of those were juvenile herring. We cannot rule out the possibility that some larval stages of fishes were consumed and digested. Most larval fish are quite small (<1cm) in length and may not be recognizable in gut contents, even after short periods (< 1 hour) of digestion. None were noted in stomachs from cage-reared salmon analyzed for gut contents. However, if fish were frequently consumed, they might not have been recognizable, even after very short periods of digestion. "

 

[fogged in]

2006...say what
Was this document posted in 2006?
and it does say
"we were unable to extrapolate the potential impact from the entire “population” of cage-reared fish on wild prey"
Can you find something that is not over 10 years old?

 

[Birdsnest]

There have been no follow up studies that I know of. This suggests this study is the current information. The study repeats that further work is required to further understand these interactions. I agree for I find these topic very interesting as I do with the topic of fish swimming clockwise or counter clockwise.

One of the primary complaints of the study was the majority of the farm samples taken where harvest fish on starve. One would suspect that starving fish in pens would be hammering any available feed of any kind but the finding show differently and suggest that fish that are being fed will show even less such interactions with wild sourced items.
I too have complained about old studies being posted on these threads but I have done so about studies that have had many following studies over the years thus making them old or less relevant i.e., sea lice studies.
This study however has no such work(to my awareness(open to correction)), which suggest to me that it is relevant unless something has changed in the last ten years that would void the finding in this work.(other than a short video of one fish taking a swipe at something unidentified)
I do not feel the study is dismissible due to its age.

 

[bigdogeh]

why not set up some underwater cameras, take a few scoops of herring or what have you and throw them in a net pen and see what happens? atlantics are piscivorous by nature. I don't think that's been bred out of them. show me that example and maybe I'll change my mind on this one issue. seems like it could easily be done. I've seen the video of atlantics eating wild fish. pretty hard to refute. I've also heard the comments from employees that have mentioned that their fish often gorge themselves on wild fish at any opportunity they get.

 

[Birdsnest]

why not set up some underwater cameras, take a few scoops of herring or what have you and throw them in a net pen and see what happens? atlantics are piscivorous by nature. I don't think that's been bred out of them. show me that example and maybe I'll change my mind on this one issue. seems like it could easily be done. I've seen the video of atlantics eating wild fish. pretty hard to refute.

Throwing small herring into a net pen would not duplicate how these herring are presented in a pen. When live chuming for tuna bait tossed out is pretty much toast for a plethora of reasons. Its ultra vulnerable after being held captive under stress and then being tossed in the open individually or separate where they'er format is to school or be part of a school for protection. This is not a very scientific method you've suggested but it may give you your desired results which unfortunately would not reflect the reality of the situation. Morton does this repeatedly.
The study confirms that atlantics do this but all our boats running around do this as well(damage/kill wild bait) to some extent, are you willing to give up boating so cut an dry.

Edit: Also cameras do not confirm consumption or species.

 

[agentaqua]

I think it would be extremely naive to think that Atlantic salmon in pens would not take advantage of feed as forage fishes - if they managed to get past the netting and into the pens. Physical placement, water flows, size of netting, and time of year (seasonality) - would all play a part as to whether or not pen fish would interact with available prey.

From the fingertips of the authors - onto the keyboard: "Our review of the literature found no accessible reports concerned with cage-reared salmon feeding and diets on wild prey in Atlantic Canada, Europe and South America farm sites. We consider this to be a knowledge and research gap."

Really? duh! would be my response. Guess this discussion over this report is a wrap...

 

[Birdsnest]

yes agent. I can see you would love to wrap this up quick. I see your the first to start using terms of "Duh" and "extremely naive". Thanks for that demonstration.

Why then is the first comment in the conclusion of the study say this: "Our main conclusions are that the “individual” cage-reared salmon consume few number of wild fish or plankton." This comment is compounded by this finding "We found that the most common wild organisms consumed were caprellids, which live on the side of net pen cages."

Edit:
The point being those organisms living on the nets would not exist if the nets were not there.

 

[terrin]

I guess that when the atlantic farmed salmon escape they would just start roaming the ocean for food pellets and since they wouldn't find any just die in short order.

 

[agentaqua]

Edit: The point being those organisms [caprellids] living on the nets would not exist if the nets were not there.

Right-on BN. yes - fish farms are in fact disguised caprellid factories. I like them so much better now. Thanks.

 

[Birdsnest]

I guess that when the atlantic farmed salmon escape they would just start roaming the ocean for food pellets and since they wouldn't find any just die in short order.

You are guessing. Perhaps you missed it or you did not read the paper. Its states that escaped atlantics adjusted/adapted reasonably well to wild feed when escaped. Luckily due to regulation and technology escapes in bc have be reduced to a minimum.

 

[bigdogeh]

https://www.voyageforsalmon.ca/salmon-farm-audit-continues/

can you explain the dfo memo? B) HERRING 1.

 

[Birdsnest]

https://www.voyageforsalmon.ca/salmon-farm-audit-continues/

can you explain the dfo memo? B) HERRING 1.

That is hearsay not science.

 

[bigdogeh]

the concerned DFO biologist and the marine harvest employees were spreading hearsay?
you sound like a lawyer, hehe. hard to dispute what one sees with there own eyes. or sees what is written on a memo. I guess the pictures and videos of atlantics eating fish could be doctored also. or maybe the fish were trained to eat wild fish and then planted into the pens... a lot of court cases are won through video evidence and documents, etc... I think a jury would convict given the evidence shown here... just imo of course.

 

[terrin]

You are guessing. Perhaps you missed it or you did not read the paper. Its states that escaped atlantics adjusted/adapted reasonably well to wild feed when escaped. Luckily due to regulation and technology escapes in bc have be reduced to a minimum.

So you want us to believe that an escaped atlantic farm fish will adjust to munch on herring but while in the net pen will look the other way at a herring and just eat pellets?

 

[Birdsnest]

So you want us to believe that an escaped atlantic farm fish will adjust to munch on herring but while in the net pen will look the other way at a herring and just eat pellets?

The study clearly shows the the fish mainly eat pellets. It also shows that fish even when on starve eat minimal amounts of wild fish. Remember what I posted above in post#3:

"One of the primary complaints of the study was the majority of the farm samples taken where harvest fish on starve. One would suspect that starving fish in pens would be hammering any available feed of any kind but the finding show differently and suggest that fish that are being fed will show even less such interactions with wild sourced items."

The question in the study isn't IF farm fish eat other items in the ocean. The question in the study is how much and what?

I get this feeling that some here feel the bc industry categorically Denys their fish don't eat other items. Please show me where this is, I want to see it?

 

[Whole in the Water]

You are guessing. Perhaps you missed it or you did not read the paper. Its states that escaped atlantics adjusted/adapted reasonably well to wild feed when escaped. Luckily due to regulation and technology escapes in bc have be reduced to a minimum.

Don't forget to mention the lack of transparency in reporting escapes and other embarrassing problems fish farms encounter. I worked inside of govt. and experienced the "cozy" relationship fish farms had with the govt. agencies that fish farms have to report to and be inspected by.

 

[agentaqua]

Don't forget to mention the lack of transparency in reporting escapes and other embarrassing problems fish farms encounter. I worked inside of govt. and experienced the "cozy" relationship fish farms had with the govt. agencies that fish farms have to report to and be inspected by.

x2 WitW! Reporting is voluntary. So - lets remove the cops from the highways - then lets ask everyone on this forum if they want to phone up the RCMP and tell them you were speeding last week - and how much over the limit?

 

[salmonkiller01]

Lets look at it differently, If each fish in the net pens eats one wild fish( or 1/10000 or 1/1000 whatever number) each during its life on the farm. How many wild fish have been eaten.Also since the paper is 11 years old how many farms are there now compared to 1986? Numbers of fish per farm ??

 

[bigdogeh]

Lets look at it differently, If each fish in the net pens eats one wild fish( or 1/10000 or 1/1000 whatever number) each during its life on the farm. How many wild fish have been eaten.Also since the paper is 11 years old how many farms are there now compared to 1986? Numbers of fish per farm ??

this is what's pretty scary...
there are millions of these fish in these net pens. an unnatural amount. they are farming more farmed fish in these areas then there are wild...
and as the wild runs dwindle, they ramp up the production of the farmed.

 

[Birdsnest]

Lets look at it differently, If each fish in the net pens eats one wild fish( or 1/10000 or 1/1000 whatever number) each during its life on the farm. How many wild fish have been eaten.

Great! Finally someone who is willing to do some quantification here. To clarify the result of atlantic salmon wild fish feed consumption in the study was less than 00.01 for atlantic salmon.(top of page 6)

Also since the paper is 11 years old how many farms are there now compared to 1986? Numbers of fish per farm ??

You can do the math and to you and me it will seem like a lot but when compared to the entire area i suspect it would be minimal.