“Anglers of the Au Sable contracted GVSU to conduct this study on the Mainstream and North Branch of the Au Sable during the Summer and Fall of 2014. 17 brook trout were tracked in an effort to better understand their use of habitat in the Au Sable system and to better inform ongoing habitat improvement projects. This study would not have been possible without the generous funding that Anglers of the Au Sable received from our partners in conservation: Mason Griffith Founders Chapter TU, Headwaters Chapter TU, Challenge Chapter TU, Michigan Fly Fishing Club, International Federation of Fly Fishers, and Patagonia Incorporated. Thank you all so much for your support!”
Dr. Mark Luttenton of Grand Valley St. University and a team of experts did some field work recently in response to the recent mud snail discovery below the Grayling Hatchery. Please read Mark’s report below. The report was sent to Anglers President, Tom Baird among others from MITU, TU Mason Griffith chapter, MDNR, and MDEQ.
A group of 6 (Terry L, Steve S, Jim W, Austin (works with Steve), Justin (works with me), and myself) surveyed four additional locations for mud snails on Sunday, they included: Gates Lodge, Burton’s Landing, Grayling Park, and just upstream of North Down River Road. Sites previously surveyed are: behind the hospital, the Main Branch below the East Branch confluence, the Main Branch above the East Branch confluence, between the I-75 bridge and Wilcox Bridge Rd., immediately below the hatchery, and halfway between the hospital site and the confluence with the Main Branch.
The Main Branch sample sites survey on Sunday were selected because they are popular access points for fishing and canoeing/kayaking. We spent approximately 40 minutes at each site and sampled the majority of habitat types at each location. This gave us approximately 240 minutes of effort at each site. We did not find mud snails in any of our collections on Sunday.
Thus far, we have only found mud snails immediately below the hatchery, behind the hospital, and halfway between the hospital site and the confluence with the Main Branch. The highest densities appear to be associated with the sites that are farthest upstream.
I have also received a note back from Joe Holumzki at USGS in Menlo Park, CA. Joe worked on mudsnails in NZ. Here is his response;
“Terry Short and I looked at the snails you sent. We think they’re Potamopyrgus antipodarum, the NZ mudsnail, smooth-shelled morph. The snails you sent are nearly morphologically identical to an invasive population I’ve sampled in Pilarcito Creek on the coast here in CA.”
New Zealand Mud Snails Documented In The Au Sable River
New Zealand Mud snails have been discovered in the East Branch of the Au Sable River, just downstream of the Harrietta Hills Trout Farm – Grayling. These invasive snails can move throughout a system and damage the fishery.
On June 6, 2016 a regional EPA lab confirmed that the snails discovered were indeed New Zealand Mud Snails. Representatives from Anglers of the Au Sable and Mason-Griffith Founders Chapter of TU will assist Dr. Mark Luttenton of Grand Valley State University, who first found the snails during routine sediment sampling, in immediately conducting additional sampling to determine if mud snails are found in any other locations of the upper Au Sable River system.
What should anglers do?
The section of river downstream of the fish farm to the confluence with the mainstem Au Sable is now confirmed infected. We encourage anglers and others to avoid fishing or wading in this section of river.
All anglers fishing anywhere in the Au Sable or nearby rivers, should take great care to prevent the spread of this invasive species.
Gear should be thoroughly cleaned and disinfected between uses.
Use a stiff brush to remove visible snails from wading shoes and waders, boats, anchors, ropes, and landing nets. Ensure that all mud and debris is removed. Take care to clean around gravel guards on waders.
Several chemicals have been found effective for killing these snails. One is full strength Formula 409 cleaner. Equipment should be soaked in this solution for a minimum of 10 minutes, then thoroughly rinsed with clean water and allowed to dry.
Snails can live for many days out of water so inspect wading boots inside and out thoroughly after cleaning.
It may also be time to reconsider using felt soles. They can pick up and hold more snails and are more difficult to clean and disinfect effectively.
If we all follow these simple precautions we may be able to help stop or at least slow the progression of this invasive species.
Mud snail identification
The New Zealand Mud snails are small, up to 1/8” in length (up to 50 can fit on the face of a dime). They range from light brown to black in color; have 5-6 whorls, of gradually increasing size from one end to the other, and are right-handed snails (meaning when held with the small tip upward, the opening should face you to your right side). They reproduce prolifically and can reproduce asexually meaning a single specimen can result in thousands of offspring.
If you think you have found a New Zealand Mud Snail contact:
Seth Herbst, DNR Aquatic Invasive Species Coordinator firstname.lastname@example.org
Bill Keiper, DEQ Aquatic Invasive Species Biologist email@example.com