Barbs and Backlashes

Calamus Carp Die-Off by whitetips
August 26, 2010, 1:06 pm
Filed under: Fishing | Tags: , , ,

I have been in the office for just a little while today and so far I can tell you by far the “topic of the day” is the ongoing die-off of common carp at Calamus Reservoir.  I have answered several e-mails and phone calls on the topic already.  So, let me tell you what we do know and what we do not know.

We have a bunch of dead carp at Calamus.  I do not know of any estimates of the actual numbers of dead carp, but as you can see from the shoreline above, it looks like “a bunch”.  Apparently it is mostly carp that are dying, and this event has been occurring for the past few days.  There are carp on shorelines that have been dead for some time as well as carp that are stressed and dying right now.  Anytime a fish die-off is comprised of mostly a single species of fish, some type of disease is a prime suspect as the cause.  There are at least a couple of diseases that are known to infect primarily carp, but at this time we do not know for sure what is causing this die-off.

It can be difficult to determine the exact cause of fish kills.  Often by the time we find out there is a problem, the fish have been dead for some time and it may be impossible to determine the cause.  When diseases are suspected it is extremely important to collect samples from fish that are distressed, dying, but still not dead.  Once the fish die, it is very difficult to detect the disease that might have caused their demise.

We have collected the samples needed from distressed carp at Calamus.  There are not a ton of fish disease experts in the country, and we cannot conduct the needed tests ourselves. So, those samples have been shipped off to a fish disease lab in the state of Washington.  We should have some results back in the next few days.

One of the diseases that has been documented to cause die-offs of carp is called koi herpes virus (koi are actually nothing more than very colorful common carp).  At this time we do not know if koi herpes virus is the cause of the Calamus carp kill.  Maybe it is, and then again maybe not.  That is why we have sent samples off for testing.

I am not a fish disease expert by any means, but I know the very mention of a “herpes” virus puts lots of ideas into people’s heads.  A herpes virus is nothing more than a widespread type of virus.  In fact herpes viruses cause cold sores and chicken pox and as you read this it is almost guaranteed that you are carrying some type of herpes virus.  Some herpes viruses can infect fish.  From what I have read, the koi herpes virus can cause massive die-offs of common carp and koi, but other species like goldfish and grass carp may carry the virus without experiencing any sickness or death.

Viruses can be present and not cause any problems or die-offs.  In fact the virus may be expressed only when the host becomes stressed.  There are a lot of diseases and parasites in our wild populations of fish that never show themselves unless the fish become stressed in some way.  In addition, the koi herpes virus apparently only causes die-offs of carp under very specific conditions.  Some fish can carry the virus and never suffer from it.

There are some external symptoms of koi herpes virus, but honestly those are symptoms similar to a lot of other diseases and conditions.  I know I sound like a broken record, but until we get the lab results back, we really will not know what is causing the carp die-off.

Some sick-looking carp in the Little York Point area at Calamus Reservoir.

I also know that a lot of folks are thinking “Eureka, there is a disease that kills carp; now all we have to do is inoculate every carp  population in the state!”  Unfortunately I do not believe it is that easy.  As I said fish diseases can be present in populations and never cause any die-offs.  If a die-off does occur it will rarely kill all fish in a population, and the survivors may then be resistant.  Also keep in mind that viruses have demonstrated an ability to mutate and spread.  Viruses that started off infecting only one host can mutate and infect another.  We know that some viruses that infect fish started out infecting only certain species, but over time those viruses mutated and began infecting other species of fish.  I said all of that to say this . . . there is a lot of research exploring a variety of techniques for controlling carp and other undesirable species of fish.  To this point I know of no “magic bullets” that selectively will eliminate carp or any other species of fish.  I have my doubts that any such “magic bullets” exist, but continued research will hopefully give us some more tools that can be useful in managing unwanted species of fish.

Stay tuned for the lab results and much more.

Thanks to Brett Brunken of our Calamus State Fish Hatchery for snapping the photos and sending them to me!


4 Comments so far
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Daryl Im planning on taking my grandkids up to Calamus in about three weeks, does this mean we can expect a bunch of dead carp on the banks ?

Comment by Dan Atchity

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