SULLIVAN — For the first time in more than half a century, tomcod have returned to Smelt Brook in Sullivan.
Last year, the Downeast Salmon Federation (DSF) removed the 50-year-old dam that kept fish out of the stream and nutrients from flowing into Smelt Cove at the head of Frenchman Bay.
“We found a few tomcod downstream of the dam and a few smelt eggs on the face of the dam last year,” DSF fisheries biologist Brett Ciccotelli said in a statement. “This year, tomcod are swimming way past where the dam used to be and are spawning in the stream again. We hope to find smelt here in the spring too.”
Atlantic tomcod, sometimes called the frostfish for its resistance to cold water temperatures, are anadromous but, unlike alewives, Atlantic salmon or river herring, they don’t travel far upstream from salt water to spawn, preferring shallow brackish or fresh water over gravel and sand bottoms.
Juveniles generally spend their first spring and summer in fresh or slightly brackish water before moving out of the streams where they were hatched into deeper salt water estuaries.
Tomcod frequently inhabit the mouths of streams and can sometimes be found in salt marshes or shallow eelgrass beds.
Around New Year’s 2018, the Downeast Salmon Federation purchased the property surrounding Smelt Brook with help from the Maine Natural Resource Conservation Program and other groups and individuals who contributed time and funds.
In the spring, classes from Sumner Memorial High School came down to survey the pond for brook trout — with fly rods and barbless hooks — and the students pulled a few of the first stones from the top of the dam.
DSF Habitat Restoration Project Manager Shri Verrill facilitated permitting, drew up a restoration plan and supervised the dam removal, fish passage and restoration of the salt marsh in September.
For half a century, sediment and nutrients were impounded behind the dam.
“There was about 2 feet of muck at the bottom of the pond,” Verrill said.
Once the excavator, bulldozers and dump trucks took out the dam and Smelt Brook ran freely into Smelt Cove, the stream — helped by rain and high tides — cut through the sediment and exposed gravel bars as far as 150 feet upstream from the old dam.
Late at night in the dark and cold of December and early January, tomcod swam under the ice and into the cove. They swam over the old dam site and for the first time in 50 years they found gravel at the head of tide where they laid their eggs.
As with many esturine fish species, the tomcod population has dropped as a result of loss of access to spawning grounds, overfishing and exposure to toxins. Because they typically live year-round in estuaries, tomcod are particularly subject to stresses from pollutants.
From what Ciccotelli has reported, local tomcod are already returning to Smelt Brook to spawn.