Skip Thompson wrote about Bacterial Coldwater Disease in his last version of Trout Aquaculture Newsletter volume 19 number 1. Here is what he has to say about it...
Bacterial Coldwater Disease (BCWD) is usually seen when water temperature is between 60-70 oF. One sign of the disease is the erosion of the tail (caudal) fin. Another sign is a discolored area above and slightly in front of the anal fin that becomes an ulcerated lesion that looks like a 'scooped-out' area.
BCWD usually affects trout less than 6" in size but chronic mortality can be seen in fish larger than 6". As the disease progresses, trout can be seen with the entire caudal fin missing with erosion of the peduncle or fleshy part just in front of the fin. Another name for the disease is peduncle disease.
Prevention & Control
BCWD can apparently enter trout eggs and is not sensitive to a standard treatment of 100 ppm iodophor (Wescodyne, Argentyne, etc). Instead eggs should be disinfected with Hydrogen Peroxide at 100 ppm (4.1 mL/gal of water at 35% active ingredient) (28.7 mL/gal of water at 5% active ingredient).
Routine flow-through treatments at 1.0-1.5 ppm Hyamine® or other quaternary ammonium compounds reportedly are effective in prevention and in the early stages of infection. However, this approach is not effective once the disease has progressed to erosion of the peduncle and caudal fin.
Stress associated with rearing density contributes to higher level of mortality. In fact, the level of mortality usually will decrease if the trout are simply split into two or more raceways, lowering the density. Mortalities and trout showing the symptoms should be removed quickly since dead trout shed almost 70 times more bacterial than live trout.
If you choose to use an antibiotic, Terramycin® (oxytetracycline) is not effective when used at the approved rate of 2.5-3.75 g/100 lbs of fish for 10 days. However, Terramycin® is reportedly effective when used at 16.5 g/100 lbs of trout for 10 days.
Aquaflor® was approved for use in March 2007 against BCWD at 0.454 g/ 100 lbs of trout for 10 days, and the withdraw period is 15 days. It is worked well in North Carolina. In most instances with BCWD, it is best to first reduce the fish density and then use the antibiotic.
Monday, June 23, 2008
Tuesday, April 8, 2008
New Bike--WooHoo!!!
Every once in awhile, we must treat ourselves. The big treat for me was a 2008 Trek Madone 5.5. It was hard handing over that credit card but again we must treat ourselves. And doesn't all this riding save me from doctors' bills. I got the bike last year around my birthday. I have been riding it ever since. Like all new bikes I have had to make a few adjustments, but lately it has been riding really well. As I say in my profile, I am a serious recreational road cyclist. But that doesn't mean I'm good. So I am learning to ride it as well.
Monday, April 7, 2008
Disease Spotlight: Ich
It is getting close to that time of year when disease problems are more prevalent! Last year for the first time I identified Ichthyophthirius multifiliis (Ich) in a carp pond. Ich has also been referred to as White Spot. Ich is highly contagious and can spread quickly.
White spots on the skin or gills of the fish is a classic sign of Ich. The white spots are like small grains of salt that have been sprinkled over the skin of the fish. Fish may also appear to be irritated and have decreased activity--don't bite.
Ich goes through a life cycle. The breeding stage is when the parasite gets on the host skin. When this stage matures it leaves the fish and produces many, many young. These young must find a fish host in order to survive. This is the free-swimming stage of Ich.
Disease Treatment
Treatment can be difficult because the breeding stage is protected. The free-swimming stage is susceptible to treatment. Since the life cycle is dependent on water temperature so is the application of treatments. A single treatment will not do the job; multiple treatments are needed. The water temperature determines the timing of the treatments. Warmer temperatures (75-79oF), treatments are performed every other day. Cooler temperatures (60oF) require treatments to be performed 4 to 5 days apart.
A common treatment is copper sulfate. Beware, copper sulfate can be toxic to fish at low alkalinities. Alkalinity must be measured before treatment. The concentration of copper sulfate is determined based on alkalinity.
Potassium permanganate is another option for those you can not use copper sulfate.
Remember, treat on sunny days. Many treatments kill the oxygen producing plankton in your pond. Have emergency aeration available. Aerators also help to mix the treatments in the pond.
Before treating, the correct diagnosis is essential. Please consult with your local extension agent about disease identification and treatment.
On a less serious note, in a local retail store in the Health & Beauty section, the aisle is labeled "Ich Relief". I chuckle to myself each time I pass it. (It is meant to be "Itch Relief").
White spots on the skin or gills of the fish is a classic sign of Ich. The white spots are like small grains of salt that have been sprinkled over the skin of the fish. Fish may also appear to be irritated and have decreased activity--don't bite.
Ich goes through a life cycle. The breeding stage is when the parasite gets on the host skin. When this stage matures it leaves the fish and produces many, many young. These young must find a fish host in order to survive. This is the free-swimming stage of Ich.
Disease Treatment
Treatment can be difficult because the breeding stage is protected. The free-swimming stage is susceptible to treatment. Since the life cycle is dependent on water temperature so is the application of treatments. A single treatment will not do the job; multiple treatments are needed. The water temperature determines the timing of the treatments. Warmer temperatures (75-79oF), treatments are performed every other day. Cooler temperatures (60oF) require treatments to be performed 4 to 5 days apart.
A common treatment is copper sulfate. Beware, copper sulfate can be toxic to fish at low alkalinities. Alkalinity must be measured before treatment. The concentration of copper sulfate is determined based on alkalinity.
Potassium permanganate is another option for those you can not use copper sulfate.
Remember, treat on sunny days. Many treatments kill the oxygen producing plankton in your pond. Have emergency aeration available. Aerators also help to mix the treatments in the pond.
Before treating, the correct diagnosis is essential. Please consult with your local extension agent about disease identification and treatment.
On a less serious note, in a local retail store in the Health & Beauty section, the aisle is labeled "Ich Relief". I chuckle to myself each time I pass it. (It is meant to be "Itch Relief").
Friday, March 7, 2008
Congratulations Sunburst Trout Company!
Kudos to Sunburst Trout Company for being awarded the Seafood Champion Award at the recent Boston Seafood Show. This is a highly prestigious award given to seafood industry leaders in sustainable, eco-friendly seafood. There were only six from around the world to win the honor. More information can be found at:
Asheville Citizen Times
Sunburst Trout Company
Seafood Champion Awards
Asheville Citizen Times
Sunburst Trout Company
Seafood Champion Awards
Grant ($$$) Possibility for NC Farmers
The Rural Advancement Foundation International-USA (RAFI-USA) Tobacco Communities Reinvestment Fund will make cost-share demonstration grants to farmers, farm organizations, and community groups in Alexander, Beaufort, Burke, Caldwell, Caswell, Craven, Cumberland, Davidson, Forsyth, Greene, Guilford, Harnett, Iredell, Johnston, Jones, Lenoir, McDowell, Nash, Person, Pitt, Randolph, Wayne, Wilkes, and Wilson counties.
Cost-share support of up to $10,000 will be awarded to individual producers and support of up to $20,000 will be awarded to collaborative farmer efforts.
Demonstration grants will be awarded through a competitive selection process. Grants will be awarded to innovative projects which show farmers a new direction or opportunity.
Priority will be given to projects that benefit farmers under 40 years of age with at least three years of farming experience and to farmers who had income from tobacco.
Deadline for applications is October 1, 2008. Funds will be available to farmers in December 2008.
For complete eligibility requirements and guidelines, visit RAFI-USA’s website at: http://www.rafiusa.org/programs/tobacco/2008cfp.pdf.
For more information or to discuss potential project ideas contact:
Jason Roehrig
919-621-0534
jason@rafiusa.org
RAFI-USA is a private, non-profit organization based in Pittsboro, North Carolina. RAFI cultivates markets, policies and communities that support thriving, socially just and environmentally sound family farms.
Cost-share support of up to $10,000 will be awarded to individual producers and support of up to $20,000 will be awarded to collaborative farmer efforts.
Demonstration grants will be awarded through a competitive selection process. Grants will be awarded to innovative projects which show farmers a new direction or opportunity.
Priority will be given to projects that benefit farmers under 40 years of age with at least three years of farming experience and to farmers who had income from tobacco.
Deadline for applications is October 1, 2008. Funds will be available to farmers in December 2008.
For complete eligibility requirements and guidelines, visit RAFI-USA’s website at: http://www.rafiusa.org/programs/tobacco/2008cfp.pdf.
For more information or to discuss potential project ideas contact:
Jason Roehrig
919-621-0534
jason@rafiusa.org
RAFI-USA is a private, non-profit organization based in Pittsboro, North Carolina. RAFI cultivates markets, policies and communities that support thriving, socially just and environmentally sound family farms.
Tuesday, January 29, 2008
Spread of the Exotic Zebra Mussel
Why is she blogging about zebra mussels? Zebra mussels are an invasive species. They were first detected in the Great Lakes in 1988, in Lake St. Clair, located between Detroit, Michigan and Windsor, Ontario. It is believed they were accidentally introduced into the lakes in the ballast water of ocean-going ships traversing the St. Lawrence Seaway.
Now to the point. Viral Hemorrhagic Septicemia (VHS) was first identified in the Great Lakes. VHS is a virus that has caused significant die-offs of different species of fish. I have heard it said that the spread of VHS might mimic that of the zebra mussel. I found this web site that follows the spread of the zebra mussel through the years. Take a look. Interesting.
United States Geological Survey Florida Integrated Science Center
Now to the point. Viral Hemorrhagic Septicemia (VHS) was first identified in the Great Lakes. VHS is a virus that has caused significant die-offs of different species of fish. I have heard it said that the spread of VHS might mimic that of the zebra mussel. I found this web site that follows the spread of the zebra mussel through the years. Take a look. Interesting.
United States Geological Survey Florida Integrated Science Center
Sunday, January 27, 2008
Genetic Research by USGS on Great Lakes VHS Strain
Winton and co-authors Gael Kurath and William Batts recently authored a new USGS fact sheet that describes important genetic information about isolates of VHSV from Great Lakes region (see http://wfrc.usgs.gov/pubs/factsheetpdf/vhsfs2011108.pdf).Other strains of the VHS virus are found in continental Europe, North Pacific Ocean, North Atlantic Ocean, Baltic Sea and North Sea.
"This Great Lakes strain appears to have an exceptionally broad host range," said Winton. "Significant die-offs have occurred in muskellunge, freshwater drum, yellow perch, round goby, emerald shiners and gizzard shad."
Genetic research at the WFRC and by colleagues from Canada showed that this strain of the virus was probably introduced into the Great Lakes in the last 5 to 10 years, and that the fish die-offs occurring among different species and in different lakes should be considered as one large ongoing epidemic. The USGS genetic research also indicated that the Great Lakes' strain of the virus was not from Europe, where three other strains of the virus occur, but more likely had its origin among marine or estuarine fish of the Atlantic seaboard of North America. The strain is genetically most like samples of VHSV recovered during 2000-2004 from diseased fish in areas of New Brunswick and Nova Scotia, Canada.
The Great Lakes' strain has now been isolated from more than 25 species of fish in Lake Michigan, Lake Huron, Lake St. Clair, Lake Erie, Lake Ontario, Saint Lawrence River and from inland lakes in New York, Michigan and Wisconsin. Experts fear the disease could potentially spread from the Great Lakes into new populations of native fish in the 31 states of the Mississippi River basin. Also, if VHS virus is introduced into the aquaculture industry, it could lead to trade restrictions as well as direct losses from the disease.
"This Great Lakes strain appears to have an exceptionally broad host range," said Winton. "Significant die-offs have occurred in muskellunge, freshwater drum, yellow perch, round goby, emerald shiners and gizzard shad."
Genetic research at the WFRC and by colleagues from Canada showed that this strain of the virus was probably introduced into the Great Lakes in the last 5 to 10 years, and that the fish die-offs occurring among different species and in different lakes should be considered as one large ongoing epidemic. The USGS genetic research also indicated that the Great Lakes' strain of the virus was not from Europe, where three other strains of the virus occur, but more likely had its origin among marine or estuarine fish of the Atlantic seaboard of North America. The strain is genetically most like samples of VHSV recovered during 2000-2004 from diseased fish in areas of New Brunswick and Nova Scotia, Canada.
The Great Lakes' strain has now been isolated from more than 25 species of fish in Lake Michigan, Lake Huron, Lake St. Clair, Lake Erie, Lake Ontario, Saint Lawrence River and from inland lakes in New York, Michigan and Wisconsin. Experts fear the disease could potentially spread from the Great Lakes into new populations of native fish in the 31 states of the Mississippi River basin. Also, if VHS virus is introduced into the aquaculture industry, it could lead to trade restrictions as well as direct losses from the disease.
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