Invasive goby helps steady population of Lake Erie water snake – via Herp Digest

Written by Kristina Smith, Watchdog/enterprise Reporter,  10/2/13

Fast facts on Lake Erie water snakes

• The snakes live only on the Lake Erie islands and prefer rocky, shoreline habitat.
• Females grow to an average of 3.5 feet in length. Males grow to 2.5 feet.
• Round gobies, an invasive fish, make up 98 percent of the snakes’ diet.
• Their average life span is 8 to 10 years, but they can live 15 or more.
• They were removed from the U.S. Endangered Species List in September 2011. They are considered a federal threatened species and listed as an Ohio endangered species.
• They mate in late May and early June. Females give live birth to about 30 babies in September. Babies tend to be the size of a pencil.
For information on the snakes, visit www.respectthesnake.com.

PUT-IN-BAY — Two years after the Lake Erie water snake was removed from the federal Endangered Species List, its numbers are robust and holding steady, a researcher said.

And the snake can thank an invasive fish for a large role in its comeback.

The resilient snakes have turned to the massive numbers of the round goby, brought to the Great Lakes through ocean-going cargo ships’ ballast water, as their main source of food, said Kristin Stanford, Ohio State University Stone Laboratory education and outreach coordinator, research scientist and herpetologist.

And the result has been a population boom of water snakes that grow faster, bigger and produce more young, she said.

Lake Erie water snake populations have thrived since the mid-2000s and are holding steady at 10,000 to 12,000 snakes, she said.

“That’s probably where they’ll stay,” said Stanford, who led a recovery plan to rebuild the snakes’ numbers. “We have been seeing kind of a leveling off of the population.”

The Lake Erie water snake lives only on the Lake Erie islands and is related to northern water snakes often seen along mainland shores. Lake Erie water snakes can be gray or have a banded brown and gray skin.

Their numbers dwindled to 2,000 in 1999. Development took over rocky shoreline habitat they prefer, and they were often killed by people who did not want them around.

The snakes are not venomous. If startled, they can be aggressive.

Females are bigger than males. They grow to an average of 3.5 feet in length, a foot longer than the males’ average.

Lake Erie water snakes’ average life span is eight to 10 years, but they can live 15 or more, said Stanford, who also is known as “the Island Snake Lady.”

Before the gobies invaded the Great Lakes in the 1990s, Lake Erie water snakes ate other bottom-dwelling fish such as sculpin, catfish and darters.

“We just really don’t see those food items in their diet anymore,” Stanford said.

Those fish are still found in Lake Erie’s Western Basin, but their numbers are much smaller since the goby invasion. Gobies are the dominant bottom-dwelling species in Lake Erie’s Western Basin, said Jeff Reutter, director of OSU’s Ohio Sea Grant College Program.

Stanford, citing a 2006 population estimate, said there are about 9.9 billion gobies in the Western Basin. Lake Erie water snakes eat about a million of those each year.

Predators of the adult Lake Erie water snakes are large birds, including herons, egrets and bald eagles. Smaller snakes are eaten by smaller birds, raccoons and other animals, Stanford said.

The Lake Erie water snake recovery is considered a huge success for endangered species. In 2011, the snakes were the 23rd species to be removed from the federal list, Stanford said.

“It is pretty uncommon,” she said. “That’s why we are very proud of the work we were able to accomplish in such a short period of time to recover the (snake) and also why the U.S. Fish and Wildlife Service uses it as an example of success.”

But that doesn’t mean Stanford’s work is done. She and her fellow researchers are in the third year of the five-year post-delisting monitoring plan for the snakes.

They continue to tag and monitor the snakes to make sure the population is not threatened and that returning the snakes to the Endangered Species List is not necessary. They also continue to educate people about the snake and its role in the Lake Erie ecosystem.

“After the plan is up, we will still likely continue to monitor the snakes because we have such a huge data set — one of the largest for any snake in the world — and we would like to keep that going,” Stanford said.