SHEGUIANDAH – An up-close photo of a Manitoulin crayfish has found a place in the pages of ON Nature magazine and, while photographer “Dr. Crayfish” is pleased to see his favourite shot receive attention, he said scenes like this are only possible in a delicate ecosystem balance that could easily shift if anglers and other water users allow invasive species to continue to spread.

“The surprising things from my Manitoulin study were that the Island was dominated by two species, except for some invasive rusty crayfish. I was surprised that the rusty crayfish wasn’t more widespread than it was, and that’s good news that it’s limited to the northern part of the Island,” Dr. Crayfish (whose secret identity is Premek Hamr) told The Expositor.

His 2013 survey took him to Bass Lake Creek in Sheguiandah, where he took the photo of a female virile crayfish in the waters near Batman’s Mill.

“I had to lie on my belly and submerge the camera right in front of it,” said Dr. Hamr, adding that he used a waterproof camera and a macro lens to capture the critter with algae on her antennae and sediment on her eyes.

Dr. Hamr, who lives in the Kawarthas, has earned the “Dr. Crayfish” name through decades of research on these freshwater crustaceans. He first studied crayfish for an environmental science undergraduate research project at Concordia University, became captivated by them and then later got a scholarship for a master’s degree in freshwater biology at Trent University.

He then netted a commonwealth scholarship to earn a PhD in zoology while studying the little-known Tasmanian giant freshwater crayfish (the world’s largest) in Tasmania.

He first assessed crayfish populations on Manitoulin in 2007.

“I always thought Manitoulin Island was fascinating because of its geology; it’s a part of southern Ontario in Northern Ontario,” he said, adding that his brother lives near the French River and he had been to Manitoulin on fishing trips.

Existing records of crayfish distribution on the Island were all but nonexistent and his brother thought he may have seen rusty crayfish near Bridal Veil Falls in Kagawong. They surveyed as many streams as they could in three days at 51 sites both on- and off-Island.

Dr. Premek Hamr, who goes by “Dr. Crayfish,” has since retired from his teaching role at Upper Canada College and devoted himself full-time to crayfish once more.

They returned in 2012 and 2013 to measure changes. They found three native species on Manitoulin—the northern clearwater crayfish, virile crayfish and common crayfish. There are nine crayfishes in Ontario and 12 across Canada.

The pair found the invasive rusty crayfish in eight sample sites, though these tended to be on the northern edge of the Island in streams flowing into the North Channel. One appeared in Lake Kagawong and they may spread to other inland lakes.

Rusty crayfish first appeared in Ontario in the early 1960s and biologists suspect that they may have spread to Manitoulin when anglers, especially those seeking bass, used them as bait and released them into the environment. They compete against native species for food and habitat.

One place where the invaders have displaced native species is Whitefish Falls. In Dr. Hamr’s 2007 study, he found few rusty crayfish and plenty of native crayfishes there; by 2012, the native populations were much smaller and the rusty crayfish were in abundance.

Although rusty crayfish populations are growing, they have not expanded as fast as expected over the five-year study span.

Many areas where the native species faced the most threats were also areas with greater human-caused habitat changes. This threatens two native species in particular, the northern clearwater crayfish and the common crayfish.

Islanders can play a role in supporting biodiversity, said Dr. Hamr.

“It’d be good if people on Manitoulin would look out for crayfish and send records in to groups like the Ontario Federation of Anglers and Hunters. They can also take pictures on the iNaturalist app or send pictures to me and I can help identify the species of crayfish,” he said.

Identification and tracking work is a major part of Dr. Hamr’s work. He is the premier (and one of the only) crayfish researchers in Canada and frequently identifies species for the Ministry of Natural Resources and Forestry, researchers, conservation authorities, schools and iNaturalist users. He also aids law enforcement when they seize imported crayfish.

Crayfish can be very important indicators of environmental health. They’re known as a ‘keystone species,’ meaning they are key to the food chain because they eat a lot of other species and are food for others. Their presence is a sign of good water quality.

“Certain species like (the common crayfish) we found at High Falls, those are pretty sensitive so you’ll never find them in waters that are too acidic or polluted,” said Dr. Hamr.

His enthusiasm for crayfish is infectious and his family has supported his research, though after a steady diet of the work he describes their interest levels as ‘tolerant.’

“My wife used to be my field assistant when we were younger but she’s grown kind of tired of it. Both of my kids have been out with me but neither of them have become biologists even though they know crayfish well, but my daughter is a science writer. She’s very supportive of my cray-ziness,” he said with a laugh.

Until last month, Dr. Hamr balanced his fieldwork with his duties as an environmental science instructor at Upper Canada College. He retired in September and vowed to “go full-time on crayfish” once he left teaching behind.

The sensitive, interconnected ecosystems on Manitoulin Island hold interest in Dr. Hamr’s mind, especially the native populations as they respond to the threats of human activity and invading rusty crayfish. He encouraged anyone near waterways to watch out for the small creatures and report their sightings.

“Don’t move them around between water bodies but make the records of them known to OFAH and on iNaturalist. Even if you just send them to me, I’d be happy to pass them on,” said Dr. Hamr.

He’s easy to find on social media—look up Dr. Crayfish on Twitter to keep current on his crustacean content.