Aquatic Connectivity and Aquatic Invasive Species: A Decision Making Framework for Fish Passage Projects in Nova Scotia

Aquatic habitat connectivity improvement projects are a very popular and widely encouraged fish habitat restoration activity in Canada. In Nova Scotia, aquatic connectivity has been embraced by community-based watershed stewardship groups as a fundamental step in the restoration process. Between 2013 and 2019, over 80 fish passage improvement projects were completed in Nova Scotia by the Adopt a Stream program and affiliate groups alone, improving access to approximately 755 kilometers of rivers and streams.

In watersheds without aquatic invasive species (AIS), improvement of aquatic connectivity at anthropogenic barrier sites (dams, culverts, etc.) is considered almost always beneficial to fish. These projects decrease the risks of isolation to resident species and increase the range of habitat for migratory species. Unfortunately, with increasing distribution of AIS in Nova Scotia, decisions to improve connectivity to expand habitat for both resident and migratory species and consequentially increase the risk of invasion by AIS have become complex.

Since 2010, the Clean Annapolis River Project (CARP) and the Nova Scotia Salmon Association’s (NSSA) Adopt a Stream Program have collaborated on several initiatives to develop tools, techniques, and training programs to assist community-based watershed stewardship groups in addressing aquatic habitat fragmentation. Coincidentally, the threat of AIS, mainly chain pickerel (Esox niger) and smallmouth bass (Micropterus dolomieu), and their distribution in Nova Scotia has grown substantially in recent years.

In an effort to address the growing threat of AIS in the context of fish passage improvement initiatives, CARP, in partnership with the NSSA through its Adopt a Stream Program, has developed this decision-making framework to guide managers in the planning and prioritization of aquatic connectivity improvement projects in the Nova Scotia context. The aim of this framework is to have a practical way of assessing the risk of isolation (i.e. maintaining, improving, or developing fish exclusion barriers) vs. invasion (i.e. providing or improving fish passage at current anthropogenic barrier sites) at current barrier sites.

For access to this decision making framework click on the link below.