Norwalk River Lamprey Spawning Survey

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We're excited to have documented the first pairs of sea lamprey, an endangered native fish in Connecticut, spawning in the Norwalk for the first time in nearly 125 years! This success was made possible by the decades of work done by passionate TU volunteers and our partners. When the Flock Processing Dam in South Norwalk was removed in 2018, the Norwalk River saw a rebirth of the migratory saltwater ecosystem that thrived for centuries before widespread development and the construction of dams which pose a barrier to fish passage to and from saltwater.

Although they look a little creepy, native sea lamprey serve incredibly important ecological functions that improve the health of rivers and make it easier for wild trout to spawn successfully. First, sea lamprey aid in nutrient cycles, bringing tons of nutrients from the ocean back upriver miles inland, feeding everything from animals, insect life, to the forest trees. Second, sea lamprey filter and clean the gravels in the summer which aids in trout spawning in the fall. 

We will meet at 10 am at Merwin Meadows Park in Wilton for a quick overview and training session on properly identifying lamprey redds, then split into to groups to cover the river downstream in search of them.