# BKD or Starving fish?



## Fishndude (Feb 22, 2003)

TheDrake said:


> I didn't know fish starved.


They do if they don't get enough to eat. Much as humans, and insects, and birds would.


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## REG (Oct 25, 2002)

Looks starving to me. Whether it is due to a birth or acquired deformity before smolting, or, a deformity/disease due to dietary insufficiency, I can't say.

I would guess if it was BKD, given the condition of the fish, one might expect to see some hematomas (bruise like spots) or some other outward lesions, but again, it's just a guess. That's what I remember when seeing BKD fish back in the late 80's, early 90's.


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## maddiedog (Nov 21, 2008)

I bet out of the MANY fish that I cleaned this summer 25% weren't stuffed with bait. I didn't go out once without marking huge pods of bait. Natural reproduction is WAY higher than people think...


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## stelmon (Sep 21, 2000)

This fish was caught out of a Lake Huron tribe. 

Judging by what REG said, I would guess this fish was starved or had some other disease. Other then the fish being skinny, the fish was perfectly fine. No legions or other marks on the fish.

...and there is a lot more natural reproduction then people think.


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## swampbuck (Dec 23, 2004)

Linda G. said:


> Please elaborate on this?
> 
> "The crash of the ales/smelt is the reason the successful spawning has increased"
> 
> ...


 
There are plenty of scientific studys regarding the negative effects of alewives and smelt on other species, But You can look them up......Heres a post by Jay Wesley to get you started........

(quote)Alewives contain thiaminase, which is an enzyme that prevents the uptake or eliminates thiamine. Thiamine in eggs can be important for survival of the egg. It affects fish differently. It might have medium to moderate impact on salmon fertility but a very high impact on lake trout fertility. 

Eggs in hatcheries are often treated with a thiamine bath to increase survival. (quote)

http://www.michigan-sportsman.com/forum/showthread.php?t=433591 Post#13


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## someone11 (Mar 15, 2009)

Was that fish tagged? Hard to tell in the picture if it was or not but if it was it would be interesting to see that data. If its a 30+ inch fish its most likely a 3-4YO fish and I would find it hard to believe it lived its whole life that size (emaciated). Could happen but rare. I did diet studies on all the fish we took from the tournaments this year on lake michigan, and i'd say a 1/4 were empty (I could go look up the % i found empty but I dont feel like it), but those fish with empty stomachs looked just as healthy as those with 30+ alewife in the stomach. And it is estimated that there is 50% natural reproduction and 50% hatchery. The CWT (Coded wire tag) program is in place to help figure out those numbers.


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## Ralph Smith (Apr 1, 2003)

stelmon said:


> Caught this fish out of the soo this weekend? Took half a minute to land it and was 36-40 inches long. Very sick looking.
> 
> 
> 
> ...


Stel, were they all from the Soo, or close to there? Looks pretty hungry to me?



swampbuck said:


> There are plenty of scientific studys regarding the negative effects of alewives and smelt on other species, But You can look them up......Heres a post by Jay Wesley to get you started........
> 
> (quote)Alewives contain thiaminase, which is an enzyme that prevents the uptake or eliminates thiamine. Thiamine in eggs can be important for survival of the egg. It affects fish differently. It might have medium to moderate impact on salmon fertility but a very high impact on lake trout fertility.
> 
> ...


Thanks for posting, makes perfect sense. I remember reading somewhere about treating of the eggs, now I know..... the rest of the story


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## REG (Oct 25, 2002)

swampbuck said:


> There are plenty of scientific studys regarding the negative effects of alewives and smelt on other species, But You can look them up......Heres a post by Jay Wesley to get you started........
> 
> (quote)Alewives contain thiaminase, which is an enzyme that prevents the uptake or eliminates thiamine. Thiamine in eggs can be important for survival of the egg. It affects fish differently. It might have medium to moderate impact on salmon fertility but a very high impact on lake trout fertility.
> 
> ...


Swampbuck, I understand where you are coming from, but significant natural reproduction had been around way before the numbers of alewife fell to levels seen currently. Also, based on the emergency rules put in place at that time (around 1994), it seemed to affect cohos more than chins.


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## swampbuck (Dec 23, 2004)

Reg, 

Theres another factor. Smelt have the same thiaminase enzyme.
The smelt populations were declining before the alewives.

While you guys are thinking about it let's look a little closer at the nasty little fish....

*What is Thiamine Deficiency Complex?​*The failure of newly hatched lake trout and other salmon species
to survive and grow has been linked in part to a lack of thiamine
(Vitamin B1) in their system. What is causing this thiamine
deficiency? Scientists have found that one of the primary prey of
these fish is the alewife, an invasive fish species that entered the
Great Lakes over 50 years ago. Alewives contain an enzyme
called thiaminase that destroys thiamine. When lake trout or
salmon eat alewife, they take in this enzyme. This is causing a
reduction of thiamine in adult lake trout and salmon and their eggs.
Symptoms of TDC in newly hatched fish include loss of equilibrium,​swimming in a spiral pattern, lethargy, and early death.
http://www.glsc.usgs.gov/_files/factsheets/2006-1 thiamine deficiency.pdf

Lake Ontario salmonines are affected by a diet-induced thiamine deficiency resulting from thiaminase that destroys thiamine. The disease is related to consumption of alewives and rainbow smelt that have high levels of thiaminase, but there is no information on the ontogeny of the disease which is necessary for evaluating impacts on affected stocks. We collected lake trout and Chinook salmon from Lake Ontario, over a broad range of sizes during 2005-2006 and analyzed stomach contents and stable isotopes (&#948;13C and &#948;15N) in their muscle tissue as measures of diet, and related changes in diet to changes in muscle thiamine concentration. We compared ontogenetic changes in Lake Ontario to changes in the same species in Lake Superior where rainbow smelt and alewives are much less abundant, and lake trout from Spray Lake, an alpine lake where alewives and rainbow smelt are absent. The transition to piscivory in Lake Ontario was associated with dramatic age- and size-related declines in muscle thiamine concentrations in both lake trout and Chinook. Based on a combination of stomach and stable isotope analysis, these declines appear to be related but are not proportionate to consumption of alewives and rainbow smelt although it was not possible to determine the relative role of each. Lake Superior lake trout also showed ontogenetic changes in muscle thiamine concentrations and limited evidence of thiamine deficiency. Low thiamine concentrations in intermediate sized lake trout in this lake were suggestive of high consumption of alewives or rainbow smelt. Increased thiamine concentrations in larger lake trout, suggested a switch to thiaminase-free prey. We conclude that salmonines in Lake Ontario that consume alewives or rainbow smelt may be at risk to adverse effects throughout the entire period of their ontogeny that they are piscivorous. As a result we recommend studies to evaluate the potential effects posed by current thiamine levels to survival throughout this period
http://www.glfc.org/research/reports/Fitzsimons_thiamine.htm


http://www.glsc.usgs.gov/_files/factsheets/2006-1 thiamine deficiency.pdf


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## REG (Oct 25, 2002)

Thanks swampbuck for the information. What we don't know is if there is a difference in the concentrations of thiaminase between alewifes and smelt. I know I can't say.


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## swampbuck (Dec 23, 2004)

Hopefully at some point science can put it all together. My primary concern is my local lake which is almost a micro copy of the great lakes in term of the changes happening. Personally I see Lake Huron as an unintended success story. The return of a stabile, balance fishery.


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