Stewardship Tip Mar 10th, 2009 – Didymo
Didymosphenia geminata (didymo) is a diatom; a single-celled algae with unique, silica, cell walls. The cells secrete a mucopolysaccharide stalk. When the cell divides, the stalk divides and forms a mass of branching stalks. The nuisance build-up is not the cell itself; it is the massive production of extracellular stalks. The stalks are made primarily of polysaccharides and protein; they are resistant to degradation.
Didymo is made up of cells that cannot be seen by the naked eye until large colonies form. It can be easily transported from one waterway to the next in fishing gear. Here are four tips to help prevent the spread of didymo.
Report: Learn to identify it. Didymo attaches itself to the streambed by stalks. These stalks form a thick, brown mat that can smother rocks and submerged plants. Established mats form flowing streamers that are tipped in white. Although it appears slimey, the algae actually feels like wet cotton. If you spot a suspected didymo colony, report it to your state conservation commission. The USDA provides additional resources to help you identify didymo.
Many infected waterways are posted. After fishing these areas, check, clean, and dry your gear before using it in another waterway. However, if you are fishing in an unposted stream or lake and you suspect that you have been exposed to didymo, take action.
Check: Before you leave a river or lake, check your gear, remove any debris, and leave it at the site. If you find any later, treat it with disinfectant and put it in the trash.
Clean: There are several disinfectant solutions that will kill didymo. Clean non-absorbent gear by soaking it for at least one minute in a solution of 5% dishwashing detergent or salt. Alternatively, soak your gear for at least one minute in a 2% solution of household bleach.
Hot water is effective and can be used in place of a disinfectant. Soak your gear for at least one minute in hot water kept above 140° F. Alternatively, soak gear for 20 minutes in water kept above 113° F.
Absorbent gear should be soaked until it is thoroughly saturated. Gear that cannot be soaked should be thoroughly cleaned with a disinfectant solution.
Dry: If a cleaning solution is not available, drying will kill didymo. Ensure that your gear is completely dry to the touch, inside and out. After the item is completely dry, wait an additional 48 hours before contact or use in any other waterway. Didymo can survive for months with just the slightest bit of moisture.
The Biosecurity New Zealand website provides additional, detailed instructions on how to check, clean, and dry your gear.
Why it is important to the fish: Large didymo colonies have been confirmed in numerous states and provinces. The thick mat that it forms can choke the organisms at the lower end of the food chain and can ultimately affect organisms at the higher end.
As anglers, we can help to stop the spread of didymo by checking, cleaning, and drying our gear.
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Their partnership makes this week’s “Stewardship Tip” possible.
Rising demand for our weekly Stewardship Tip and a new partnership with Fly Cast America now makes the Stewardship Tip available in Spanish. Ahora, reciba el Stewardship Tip en español. Gentileza de Fly Cast America.
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