The fish migration gets dense in areas of Westbrook’s Mill Brook Preserve, making it a popular destination. Contributed / PRLT

The Presumpscot Regional Land Trust is looking for volunteers for the upcoming fish migration season to help with an expected surge in visitors to Mill Brook Preserve in Westbrook.

Thousands of alewives swim up the Presumpscot River each spring to spawn and are particularly visible at the preserve, which attracts a big crowd. With an increase of visitors during the pandemic, the PRLT is expecting even more onlookers. It’s looking for at least 20 more fish migration ambassadors to greet visitors, share information with them and make sure they stay out of the river and pick up after themselves.

“This is a unique volunteer experience unlike anything else I’m aware of in the region,” said PRLT Executive Director Rachelle Curran Apse. “For those who love wildlife in action, you can be on site and engaging with people to help ensure things go well. It’s like being in a national park.”

Most migration viewers watch from about a mile into the preserve, where the river bottlenecks and and thousands of fish can be seen swimming through the lower falls and river.

“With the incredible numbers of people coming to view the experience, what we realized while this was happening was more of a national experience,” Apse said. “You have volunteers greeting people, giving some background about fish migration, the importance of conservation and water quality.”

The ambassadors also help keep the fish safe on their journey.

“The primary things that negatively affect the migration is when people or dogs go into the water or fish pools at the lower waterfalls,” Apse said. “If people or dogs go in that water it can cause stress on the fish and result in them not migrating. Also, people keeping dogs on leashes and (making sure they are) keeping up after their dogs, because collectively that’s a big impact.”

Apse said there is no real way to count visitors with the four trailheads as access points, but pre-pandemic she would easily count hundreds just during a quick stop. Now, with heightened interest in outdoor activities due to the pandemic, she expects even more.

The migration tends to happen mid-May through June and runs anywhere from two to four weeks. However, with weather conditions as is, Apse said people should keep their eyes out for an early migration due to a change in water temperature.

“It could be weeks early this year, could be two weeks from now,” she said.

The PRLT is looking for a number of volunteers for other opportunities as well, including five water quality testing roles, she said.

To see a list of volunteer duties and sign up, visit prlt.org/get-involved.