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Author Topic: Mortality Rates  (Read 4707 times)

Geff_t

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Mortality Rates
« on: January 06, 2009, 09:26:31 AM »

I do not know how many of you have read this already but I found it really interesting.

Just have read this in the new" BC OUTDOORS Sport Fishing"

I think think this info will bring some funny looking faces for sure so here it goes.

"Numerous studies,many carried out here in BC,have provided actual survival rates for caught and released fish from the recreational fishery.
In the ocean environment,for example,studies from BC and Washington State show that survival rates range from
85 to 99 % for legal sized salmon.All studies have shown clearly that 99% of fish mortality comes from hook injury,not from handling or any other factors.

Fish feeding aggressively tend to have a lower survival rate because they take the bait or lure deep thus increasing the chance of the hook striking a lethal point.

Bait is often claimed to be the "fish killer" in angling,but the study shows otherwise.A long term study of the Nicola River herein BC dealing with chinook salmon taken on salmon roe,shows a survival rate in excess of 97%.A similar program in the shushwap river showed a 94% survival rate,while one on the Skeena came in at 96%.A study of the migration and spawning patterns of the Chilliwack River showed a 98% survival rate again using bait.

This past august and september,the DFO and the angling community began the first of four planned test studies of the survival rate of sockaye salmon caught and released in the Fraser River.Bottom bouncing,or "FLOSSING",was was the angling method used.Up until this year,the DFO had been using a maximum 90% survival rate for these fish caught and released in the recreational fishery.This past summer,despite a very low return,volunteer anglers of all skill levels managed to catch and land 174 sockeye.They were held for 24 hours in net pens and then released after that.Any mortalities were autopsied and the cause of death ascertained.

Throughout the course of this study only two sockeye died, only one of which could be identified as having died as a result of fishery impact.The results of this first study show that sockeye caught and released in the Fraser river recreational fishery have a survival rate of 99.5%,which was much higher then many of us expected.Experience tells me that similar results can be expected over the balance of the study.The results seem to prove that anglers in this fishery pose no threat to Fraser River sockeye stocks."


Very, very interesting..........
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dennisK

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Re: Mortality Rates
« Reply #1 on: January 06, 2009, 09:36:51 AM »

Quote
All studies have shown clearly that 99% of fish mortality comes from hook injury,not from handling or any other factors.

I've always believed that - but it just does not "look" nice tossing a fish like a football back into the river lol.

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Chrome Assassin

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Re: Mortality Rates
« Reply #2 on: January 06, 2009, 11:08:57 AM »

I heard those nimbers quite a few months ago but was scare to post them cause I didn't want to have to debate them all day long. I have a few friends that guide for different companies that mainly the Fraser system and they've all heard the same numbers as well. Let the debate begin....
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chris gadsden

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Re: Mortality Rates
« Reply #3 on: January 06, 2009, 11:28:45 AM »

Let the debate begin....
The concern I would have with the sockeye study that was held on the Fraser was the sockeye after being flossed were held in a holding pen under ideal conditions for 24 hours before released. The question I ask is how well they would survive if they are released immediately back into the river and if they would be able to continue their journey to their natal streams hundreds of miles away.

I brought this up at the Upper Fraser Valley Sportsfishing Advisory Board meeting when the study results was put to the board members by the contractor that coordinated the study. I said in the future radio tags should be put in the sockeye like other studies that have been done in the past on steelhead and chinooks. They said that would was being considered in the future. I think that would maybe give a better idea on how they actually survive catch and release but then they will have to avoid hundreds of nets ahead of them and the tags are very costly.

Fish Assassin

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Re: Mortality Rates
« Reply #4 on: January 06, 2009, 11:33:14 AM »

Excellent point Chris.
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Geff_t

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Re: Mortality Rates
« Reply #5 on: January 06, 2009, 11:35:46 AM »

Chris I also believe the study would of turned out differently if the sockeye would of been dragged up the beach and booted back to the water like we see happening all the time.
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BwiBwi

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Re: Mortality Rates
« Reply #6 on: January 06, 2009, 01:01:22 PM »

Have you guys read study done for mortality rates on coho salmon?
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chris gadsden

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Re: Mortality Rates
« Reply #7 on: January 06, 2009, 01:16:43 PM »

Have you guys read study done for mortality rates on coho salmon?
Are you talking about the one they did on the Lower Fraser using bait by bar fishing  on the bottom?

BwiBwi

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Re: Mortality Rates
« Reply #8 on: January 06, 2009, 01:21:08 PM »

yes
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Fish Assassin

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Re: Mortality Rates
« Reply #9 on: January 06, 2009, 01:37:37 PM »

And the results were ???
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chris gadsden

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Re: Mortality Rates
« Reply #10 on: January 06, 2009, 01:42:56 PM »

yes
I think the mortality rate was  high and a good percentage of the coho were jacks. These fish en-haled the stationary bait. Each type of fishery has different effects on fish as does water temprature.

I know in all the years of steelhead fishing and I use bait most of the time I maybe have had one bad bleeder while float chinooks at creek mouths and chinook jacks in the Thompson the incidents of deep hooking is higher.

Of course the debate on using bait vs other methods gets lots of debate and that will continue long after I have made my last cast.

fishnjim

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Re: Mortality Rates
« Reply #11 on: January 06, 2009, 07:26:28 PM »

hook size could also play a factor in the mortality of the fish.  it is interesting to hear that the bulk of the fish mortality comes from the hooking of the fish.  it still seems tough to believe that, as it still seems more fish would die from poor handling versus deep hook sets in the mouth or ingested hooks.  anyways, i hope they continue a few more studies of this nature with different species and at different times, different angling methods etc. etc.
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BwiBwi

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Re: Mortality Rates
« Reply #12 on: January 07, 2009, 12:30:27 AM »

It's not that hard to believe. Salmon leap on to rocks swim across shallows, scraping their bellies on rocks and still makes it to spawning ground.
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buck

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Re: Mortality Rates
« Reply #13 on: January 08, 2009, 08:14:25 PM »

This past summer a number of sockeye were transported to Cultus Lake for experimental studies. These fish appeared fine for the first week and then began to show signs of severe fungus infection.
After ten days the majority of these fish were compromised and eventually died. Also a number of Cultus fish met the same fate after being handled due to warm water conditions. 
Yes,  the study showed that you can catch and release sockeye and after 24 hours they look fine, but the real test comes after 10 days. Last summers temperatures were not excessively high and mortality
rates will soar after 10 days if we were to have a hot summer.           
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BwiBwi

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Re: Mortality Rates
« Reply #14 on: January 08, 2009, 10:46:12 PM »

Unfortunately no mortality studies would last that long.  Not in the States and not in Canada.  Best way to study mortality rate would be to catch and tag (radio tags).  Follow out it's entire journey. 
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