Habitat Connectivity

The primary measures of success are to restore or protect 100 habitat patches and reconnect 175 miles of riverine migratory corridors in the Connecticut and New York portions of the watershed. Of the 175 additional miles of riverine migratory corridors, 50 percent of the miles will occur in locations where communities have not typically benefited from habitat connectivity projects.

Status & Trends

The Partnership is currently working on the development of a model to identify locations, on a parcel-level, of potential restoration projects to increase habitat patches and, therefore, restore habitat connectivity.

When the Fish Passage Initiative began in 1998, a total of 1,859 miles of all the rivers and streams in Connecticut were potentially passable. This represents the total river and stream mileage known/thought to have supported anadromous fish at some point in history. In 1998, 59 percent of all rivers and streams in which fish could swim upstream were passable. As of 2024, 83 percent of potentially passable river miles were reconnected. Since 1998, we have restored 448 river miles, constituting a 24 percent increase.

Eleven new stream miles were reported opened in 2024, due to the Harrington Apartment Dam Removal and creation of the Shewville Dam Fish Ladder in Connecticut. Two additional projects, a fishway and a dam removal, were completed in Connecticut in 2021. However, these projects will not result in opening fish passage to Long Island Sound until barriers at downstream dams are removed. One of these projects, a fishway at the Upper Collinsville Dam in Canton, will open 32 stream miles once downstream barriers are removed.

Challenges

Improving habitat connectivity— the degree to which the landscape facilitates fish and wildlife movement between different habitat or resource patches—is relatively straightforward within streams compared to terrestrial habitats. When an obstruction to the passage of fish is removed, or even when the flow of water is improved, connectivity increases.

Barriers also need to be removed to improve connectivity on land between two nearby parcels with valuable natural resources, such as forests. Connecting terrestrial habitats can be challenging because the barriers may include community assets, such as roads and residential and commercial uses. Determining a baseline and measure of success for land-based connectivity has been difficult to measure up until now. Recent higher resolution imaging from satellites, now under review, will enable the Long Island Sound Partnership to more effectively assess land-based habitat connectivity.

While river connectivity efforts have been successful, further progress is needed to support the daily needs of fish and other aquatic species. Facilitating collaboration between restoration practitioners and owners of property with river/stream barriers is often a complicated process that takes time, information sharing, and engineering analyses.

Importance

Habitat connectivity is a critical component of wildlife conservation. Protecting existing coastal habitat patches (i.e., discrete habitat areas that are isolated) prevents loss of areas where connections can be restored. Restoring areas between isolated habitat areas increases the habitat connectivity (i.e., contiguous acres of coastal habitat protected or restored). Assuring fish and other wildlife have connected habitat to support their day-day needs like feeding, breeding, resting, and migrating assures that diverse ecosystem functions are maintained and that the resources we rely on as humans (i.e., fishing, forests, etc.) are available to sustain our needs.