Glass Eel and Elver

Elver Abundance Study – East River, Chester

Project Summary

Coastal Action is currently conducting an elver abundance study on the East River in Chester. The project is a continuation of research originally carried out by Fisheries and Oceans Canada (DFO) which began in the late 1990s. Coastal Action took over the project in 2008 and continues it annually. 

The purpose of the study is to determine elver recruitment on the East River and to use these numbers to estimate how many elvers are arriving at Nova Scotia’s rivers. Also, there is a commercial elver fishery on the East River, therefore data from the commercial harvest, past DFO research, and Coastal Action’s current study can be compiled and compared to assess the health of elver populations in Nova Scotia and to determine if elvers are being harvested in a sustainable manner. 

The East River is located in East Chester, Nova Scotia. The East River was chosen as a site to monitor elver recruitment due to the commercial fishery on the river, as well as the waterfalls at the mouth of the river that act as a natural barrier to migration. Thus, traps set up below the falls will catch the majority of the elvers travelling upriver with little escapement. 

The traps designed to capture the elvers use water flow to lure the eels, as they swim against the current to travel upriver and are attracted to the lower current on the ramps to the traps. The small ramps with slow flowing water enable the elvers to climb up the ramps and be flushed into an adjoining holding box. 

Elvers primarily run at night and are influenced heavily by the tides; therefore, traps are typically checked and emptied early every morning. Researchers remove and measure the total mass of elvers in each trap and conduct biological sampling on a sub-sample of individuals. Once measured, the elvers are released further upstream from the falls. 

The study starts annually in early spring between April and May. Timing of the runs varies on conditions, but generally the elvers begin entering the rivers once water temperatures have reached about 10°C. Typically, the run ends by mid-July and traps are removed. 

In recent years, Coastal Action has found that elver recruitment in East River is increasing. During the 2014 field season, 1.7 million elvers were captured and released. This is the largest yearly total to date.

If you have any questions, please contact Danielle Pernette at (902) 634-9977 or danielle@coastalaction.org