Perch with VHS

[SteelEd]

Has anyone else been frequently catching perch with possible VHS? The reason I ask is because I caught on on Sunday and one on Monday that both appeared to have this disease. Both were nice perch, but the one on Monday was an almost 12" female that just looked sickly and had the red spots near tail. I obviously discarded the fish, but after I cut them to determine the sex. Sorry, but I did not take pictures.

Ed

[Gone Fishing]

In my opinion, I think you are looking at wound marks that are healing caused by predators that took a nip. I've seen plenty like that but inside they look fine. I asked the question to a fishery biologist about VHS in Perch in LSC and he wasn't aware of any problem. I hope that is true.

[SteelEd]

They did not appear to be wounds to me. Both fish had actual lesions that were red in color. They also seemed underweight and quite skinny for their size. Strange:dizzy:

Ed

[fishfly]

I read on the DNR page that eating a fish with VHS is harmless.

[MSUICEMAN]

why cut them? if you think they had vhs whats the point anyways?

[SteelEd]

Also checking for internal signs. I did not want to chance eating them. Are the lesions caused by something else or are they VHS?

[Ed Michrina]

There are a bunch of parasites and diseases that fish get . If you catch a diseased fish your better off keeping it and discarding it. Better that than putting it back to swim with healthy fish. The MDNR web site has a list (with photos( of fish disease/parasites

[PerchOnly]

Take a look at this link on the DNR site, VHS looks kinda unique and it appears that you see the blood?? lines.

http://www.michigan.gov/documents/dnr/vhs-photos_190459_7.pdf

I too read that they say that it's ok to eat the fish that has it, personally I'd pass.:dizzy:

Some of the pictures are perch from LSC :SHOCKED:

[Mike Thomas]

First, let me make it clear that Lake St. Clair yellow perch have tested positive for VHS during past years. A minor, but noticeable die-off of yellow perch was observed during spring 2006, and one yellow perch collected at that time (still alive but clearly in poor condition) tested positive. That fish had no exterior sign of the virus, that is, no lesions, or marks of any kind visible.

As for the lesions on yellow perch. We've been seeing an increase in red sores or external lesions over the past 5 or 6 years in our fish surveys, and also hearing more reports from anglers. We've collected samples and had them examined by the Animal Health Lab at MSU. Lab work revealed the presence of several types of bacteria, commonly known to cause disease in fish. Pseudomonas flourecens was one of the bacteria. The Piscirickettsia bacteria (Muskie Pox) was also found in yellow perch and can cause similar lesions. Fungus (Saprolegnia) is often associated with the lesions and can result in a brownish or white-colored spongy or cottony looking surface on the sore. Similar secondary infections can also occur from wounds caused by predator attacks.

Ontario Ministry of Natural Resources collected yellow perch with sores in Lake Erie a couple years ago. Here's the results of the samples they had tested...

"They had columnaris disease caused by the bacteria Flexibacter
columnaris. This bacteria is widespread, and starts to thrive in warmer temperatures (ranges differ but 13-15 degrees Celsius and greater). The bacteria causes disease particularly when fish are stressed (ie: temperature,
crowding etc.) The bacteria infects numerous fish species and some amphibians; it is found in soil and water. Salmonids, muskies, walleye, catfish and baitfish are vulnerable under intensive culture conditions. The
bacteria can overwinter on fish and microcysts produced can last years.
It sounds like recent die offs of perch may have been associated with
this bacteria. Some of the fish we examined (but did not cut open) had
milt running. Maybe stress associated with spawning contributed to the
disease."

Cooking destroys all of the above infectious agents. I don't advise anyone to eat raw Great Lakes fish as parasites can be a problem. Deep frying is my favorite way to insure sterile perch fillets for the table!

Mike Thomas
MDNR
Lake St. Clair Fisheries Research Station
thomasmv@michigan.gov

[SteelEd]

Mike - Thanks for all the information. I really appreciate you taking the time to answer my questions.

Ed

[D and L]

As for the lesions on yellow perch. We've been seeing an increase in red sores or external lesions over the past 5 or 6 years in our fish surveys, and also hearing more reports from anglers..... Fungus (Saprolegnia) is often associated with the lesions and can result in a brownish or white-colored spongy or cottony looking surface on the sore.
Mike Thomas
MDNR
Lake St. Clair Fisheries Research Station
thomasmv@michigan.gov

Thanks Mike, Very informative! That Saprolegnia fungus describes exactly what we have been seeing on the perch lately ( posted a picture of it on an earlier thread) . There IS a fungus amoung us :dizzy:
OH, and NO perch sushi for ME.
Laura

[PerchOnly]

Yes, thanks for the info. Glad that the DNR is continuing to monitor/read threads on this site.

However, I am still not knowingly going to eat a fish with a lesion or an infection. Fried, baked, smoked or sushied:lol::lol:

[stinger63]

I suppose all these different bacteria are caused from run off sources of raw sewage entering our water ways and or coming from foreign freighters entering our waters ways.It makes the fish look disgusting.

[MSUICEMAN]

can be lots of things... sewage, fertilizer, industrial releases or runoff....

[Mike Thomas]

Given the concerns some people have about eating yellow perch with visible external sores, I thought they might find this interesting too.

During our survey on Lake Erie 2 weeks ago, we observed a major bloom of toxic algae (Microcystis) and saw anglers perch fishing amidst the bloom. I wondered if there was any health threat from eating perch coming out of that water....and just today saw the results of a recent study that indicated the toxins are not accumulated in the perch muscle tissue at high enough levels to be a health threat. The toxin is accumulated at high levels in the perch liver tissue, so I don't recommend perch liver pate from Lake Erie - at least during algae blooms. Incidentally, we don't see much Microcystis algae on our side of Lake St. Clair, but it can show up over in the plume of water from the Thames River along the South shore. Here's the details of the toxin study for anyone interested.


Authors AE Wilson, DC Gossiaux, TO Hook, JP Berry, PF Landrum, J Dyble, SJ Guildford
Title Evaluation of the human health threat associated with the hepatotoxin microcystin in the muscle and liver tissues of yellow perch (Perca flavescens)
Full source Canadian Journal of Fisheries and Aquatic Sciences, 2008, Vol 65, Iss 7, pp 1487-1497

Abstract During the summer of 2006, the western basin of Lake Erie experienced a bloom of the toxigenic cyanobacterium Microcystis aeruginosa. Across 11 sites, intracellular, particulate-bound microcystin levels in the seston increased to levels that exceeded World Health Organization guidelines for drinking water exposure (1 mu g toxin-L-1). In contrast, toxin concentrations in yellow perch (Perca flavescens) muscle tissue (n = 68) declined from June to August, were negatively related to algal toxin levels, and never exceeded a conservative chronic exposure concentration estimated using proposed United States Environmental Protection Agency (US EPA) guidelines. Microcystin concentrations in yellow perch liver exceeded US EPA chronic exposure guidelines, were on average 125 times higher than muscle toxin concentrations per unit dry weight, and varied little throughout the summer. With current guidelines, humans do not appear to be at risk when consuming the muscle tissue of Lake Erie yellow perch collected during large-scale cyanobacterial blooms. However, this study highlights the need for a better understanding of the trophic transfer of cyanobacterial toxins through aquatic food webs in diverse ecosystems with an emphasis on understanding if these compounds could accumulate sufficiently to affect human health.