As most readers of my posts know, I am a stickler for fact based conclusions and the felt sole controversy is filled with incorrect assumptions.
- Felt soles are the primary method of spreading dydimo from one place top another and are the cause of dydimo blooms that are now occuring where they have not before.
Factoid - The scientist who started the Dydimo controversy has admitted his initial conclusions were wrong. Dydimo blooms are not caused by the felt boots but by changes in water chemistry.
Max Bothwell, a research scientist for Environment Canada, who wrote an influential article that linked angler's felt soled boots to dydimo spread has now reversed himself and said that anglers are not responsible.
Here is his original article, On the Boots of Fishermen:
He now believes that dydimo has been in North American waters and that it is a change in water chemistry, specifically lower phosphorus levels that has caused dydimo blooms.
Why is phosphorus lower - The clean water act decreased the usage of phosphorus in fertilizers and mandated the removal of phosphorus during waste water treatment. Less phosphorus in rivers ===> Dydimo Blooms.
Read the article in American Angler, July-August, 2013, pp 8-9.
"'I no longer believe the problem is North American streams is the result of it (dydimo) being moved around.' …. Scientists are now convinced that dydimo lives in many streams, but blooms only when the water has far less than the normal amount of phosphorus…… The most damaging dydimo episode in the US seems to have been on Rapid Creek in South Dakota, where a six-mile bloom dramatically impacted a blue ribbon brown trout fishery. In 2007 and 2008, Bothwell and other scientists added phosphorus
to sections of Rapid Creek. Sure enough, the dydimo mats shrank"
- Dydimo is a relatively new “invasive.”
Fact - Dydimo has been documented in the sediments of lakes as long as 900 years ago. Dydimo was present in North America in as early as 1218 AD, in the sediment at the bottom of Naknet Lake dated by a volcanic eruption. So who brought didymo to Alaska well before any Europeans even know it existed?
'We found no statistically significant change in the numerical presence of D. geminata or D. clavaherculis, as a group, in Naknek Lake between the years 1218 and 2003."
Historical abundance and morphology of Didymosphenia species in Naknek Lake...: EBSCOhost
- Dydimo harms trout and insect populations.
Fact - Where studies of trout populations before and after dydimo blooms have been performed, there has been change due to dydimo blooms.
”…even though the research showed that there was a higher proportion of small invertebrates, the greater density all round meant that even the larger invertebrates that trout prefer were also more abundant at sites affected by didymo.
…there was no evidence yet that didymo was having an adverse effect on the abundance or size of trout. At this stage, negative effects for anglers were matters of aesthetics and inconvenience (fouled fishing lures and the need to clean equipment). Indeed, anecdotal accounts from Fish and Game New Zealand suggest that there had been excellent mayfly hatches (an important source of trout food) and good fishing in some didymo-infested rivers last summer.”
Didymo effects on river invertebrates: not as bad as feared? | MPI Biosecurity New Zealand
- When felt soles are banned, no one can use felt soles.
Fact - The states that I know of that have banned felt soles have an exclusion for federal workers and state workers. These states know that rubber soles are more dangerous than felt and forcing emergency and state workers to use felt places these workers at risk for injury and death.
So there an exception for State and Federal Employees:
Vermont has banned felt boots but if you investigate the law, it exempt state and federal employees. They can continue to wear felt.
"Sec. 1. 10 V.S.A. § 4616 is added to read: § 4616. FELT-SOLED BOOTS AND WADERS; USE PROHIBITED
It is unlawful to use external felt-soled boots or external felt-soled waders in the waters of Vermont, except that a state or federal employee or emergency personnel, including fire, law enforcement, and EMT personnel, may use external felt-soled boots or external felt-soled waders in the discharge of official duties.
The proposed Montana law does the same. I have read that the reason this died in committee was because government employees wanted the security of felt soles and lawmakers could not agree that this was fair to the public.
"NEW SECTION.**Section 2.**Use of felt-soled boots and waders prohibited.
(1) A person may not use external felt-soled boots or external felt-soled waders in the waters of the state.
(2) The possession of external felt-soled boots or external felt-soled waders on the banks or shores of a stream or lake or in a boat, raft, canoe, or other water vessel is prima facie evidence that the person or persons in whose possession the boots or waders are found were using the boots or waders in the waters of the state.
(3) The provisions of this section do not apply to a state or federal employee or emergency personnel, including fire, law enforcement, and emergency medical technicians, using external felt-soled boots or external felt-soled waders when acting within the scope of duty.
- It is easy to decontaminate boots and waders without harming them. There are non toxic chemicals that can kill all invasives.
Fact - there is not a single decontamination method that will work for all invasives. Some work for dydimo but they will not work on NZ mud snails or whirling disease. So you have to pick the invasive that you want to protect against. Who will take the time to research what to do for every invasive?
The other problem is that decontamination with some chemicals actually shorten the life of waders and wading boots. Download this State of California DFG study on methods of decontaminating for New Zealand Mud Snails to see the damage done to waders and boots.
In January or 2007, the EPA and The Federation of Fly Fishers published a white paper on Dydymo. The white paper says:
"While decontamination will not destroy all invasive species
, cleaning procedures minimize the possibility of spread. These simple treatments effectively destroy D. geminata algal cells (Kilroy 2005):" The white paper then goes on to recommend a 2% solution of bleach. Clorox is a 6% solution so a 2% solution 2 parts water to 1 part Clorox. Try putting just a drop of that on a pair of blue jeans and see what happens.
So the both the California Dept of Fish and Game and the EPA recommend what I consider to be harsh chemicals. They also admit that there is no single magic treatment for all invasives. Clorox shortens the life of waders and boots.
- The campaign to clean wading gear can stop the spread of Dydimo into new areas so we should still get rid of felt soles.
Fact - Even in New Zealand, a much smaller ISLAND nation than the USA, with heavy fines and jail time for spreading invasives and a total ban on felt soles, dydimo continues to spread.
The inconvenient truth is that rubber soles might delay, but not prevent the spread of didymo in the more heavily used rivers of the USA.
Because of the heavier use of rivers in the USA vs New Zealand and poor enforcement, I would expect a faster spread even with rubber soles.
Even the New Zealand Biosecurity Agency says that there is no way to stop Dydimo or eradicate Dydimo:
"Can I receive a fine if I spread didymo?
Didymo has been declared to be an Unwanted Organism under the Biosecurity Act 1993. It is an offence to knowingly spread an Unwanted Organism with penalties of up to 5 years imprisonment, and/ or a fine of up to $100,000.
Will didymo continue to spread to rivers throughout New Zealand?
Yes. Didymo will likely continue to spread to unaffected areas within New Zealand.
Research on the environmental variables which control didymo's growth (water depth and flow rate, nutrients, light, invertebrate grazing, etc.) has helped identify which habitats and locations it is most likely to establish. Ongoing passive and active surveillance will help determine rate and range of spread.* Human activities are considered the most likely source of spread of didymo between rivers and catchments."
Can didymo be eradicated in New Zealand?
No. Eradicating any microscopic organism from a natural environment is virtually impossible, especially in an aquatic environment.
We know of no systematic attempts to eradicate invasive blooms of didymo. This is likely because of its widespread distribution and because in a number of countries it is considered a native species.
While we work to understand more about the physical, chemical and biological factors which control didymo, our efforts will continue to be focused on reducing the spread from known affected river systems."
FAQs related to Didymo | MAF Biosecurity New Zealand
The USA has a population of over 300 million and New Zealand has just over 4 million. We have 100 million sport fishers, NZ has 1 million.
New Zealand has the most rigid laws (The fine for spreading Dydimo is 5 years in Prison and/or a $100,000.00 fine) to prevent dydimo spread and yet it continues to spread. Dydimo has spread to other areas in every year since it was discovered in 2004 and restrictions were placed in 2005.
We have 300 times the population, small fines and no jail time; and yet there are those that believe that rubber soles will stop the spread of dydimo. Clearly that ignores the evidence.
Spread is inevitable. The question then is whether the extra cost and risk of injury is worth any delay that may result.
What we do know is that anglers are voting with their $$$ that felt is safer than rubber
( Simms Plans About-Face on Felt | Angling Trade
). We know that even high fines and jail cannot stop the spread of Dydimo. We know that studies of Dydimo and trout show that trout populations are not decreased.
So the facts are:
1. Dydimo blooms are not caused by fishermen.
2. Dydimo was in North America and spread well before the invention of felt boots.
3. Aquatic insect populations and trout populations are not harmed. Dydimo does not decrease but has been shown to increase invertebrate biomass where it has been studies in NZ.
4. State and Federal Employees refuse to use rubber soles because they are less safe. Therefore these laws place anglers at risk.
5. Decontaminantion for all invasives requires multiple different chemical that will eventually destroy your wading gear. This means that no one will properly decontaminate their gear.
5. Biosecurity of NZ admits their laws cannot stop the spread of dydimo and this fact has been demonstrated by continued spread despite high fines and jail time.
Therefore, spread in the USA is inevitable despite law requiring rubber soles.
Fact 1, 2, 4, and 6 indicate we are risking angler injury, permanent disability, and death for a modest delay in dydimo spread. Fact #4 indicates that anglers may be disabled or die for an organism that does not decrease or damage the invertebrate or fish populations. Fact 5 shows that no one will “properly” decontaminate their gear anyway.
The inconvenient truth is that the felt sole ban is “feel good” legislation that makes legislatures and fly fishers think that they are doing something, when in fact, they are doing very little.
What do I do? I use a different set of wading boots for Wisconisin and Montana. I use the same waders, but I make sure they are absolutely dry and inspected before use them in a different area.