The number of alewives returning to spawn in the St. Croix River has exploded this year, dramatically surpassing counts from recent years and boding well for the restoration of the species.
As of July 20, a total of 157,750 alewives were counted crossing the Milltown dam, located near the river mouth along the Maine and New Brunswick border, according to Heather Almeda, manager of the St. Croix International Waterway Commission. By comparison, 33,106 alewives were counted in 2016, and 93,503 in 2015. The waterway commission also counted 54 American shad crossing the fishway in July, another keystone species that officials want to see return to the river, Almeda said.
The state of Maine passed a law in 1995 that ordered fishways along the US side of the St. Croix – at the Grand Falls and Woodland dams – closed due to fears that the alewives were negatively impacting the bass sport fishery. The population of alewives and shad entering the waters crashed significantly after that. Studies later confirmed those fears were unfounded. Maine eventually changed its law to open the Woodland Dam in 2008; the Grand Falls dam was the final barrier on the US side until that fishway was re-opened in 2013. Since then, Almeda said, populations have been recovering in what has historically been part of the alewives’ spawning habitat.
Furthermore, since alewives will continually revisit the same river to spawn year-after-year once they reach maturity, the numbers should continue to increase annually from here on out, according to Harvey Millar, New Brunswick area manager for Department of Fisheries and Oceans Canada (DFO).
“They come back when they’re four years old, and then years five, six, seven, they just keep repeating (the trip),” Millar said. “The numbers will keep building rapidly now.”
Millar said the Peskotomuhkati Nation (Passamaquoddy) were close collaborators in getting the river re-opened, alongside the US Fish and Wildlife Service and DFO. The fish runs involving anadromous species (which live in the sea but enter freshwater rivers to spawn) are not only important to the Peskotomuhkati people as a food source and a part of their culture, he explained. Fish that live predominantly in the sea don’t have the same degree of chemicals as those that stay entirely within the river – thus making it safer to eat them in greater amounts in certain cases.
Alewives are used commercially as lobster bait, and salted and sold as food, Almeda said. The fish coming in from the ocean also help strengthen the food web in the river, providing additional prey and nutrients to predators such as eagles, ospreys, cod, striped bass, turtles, otters and salmon living in the St. Croix area.
Millar said New Brunswick Power, which owns the Milltown dam near the river mouth, also has helped draw fish to the Milltown fishway by turning off one of its power turbines during the run so that it wouldn’t detract alewives from their path. The power company is exploring new technology to attract alewives toward the fishway, Millar said, and is trying to determine effective methods to allow additional shad to come through – as they don’t like the existing fishway. Other species that historically traveled up the St. Croix to spawn – striped bass and eel – don’t seem to use the existing fishways (though American eel have been found upriver despite that dislike of the fishway), so other pathways may be needed to provide or improve access.
Looking ahead, Almeda said the waterway commission is interested in seeing how much suitable habitat is available past the dams and how well the alewives – and American shad – can reach it. They’ll be tagging fish and following their progress along the river to see if they can reach and use the ponds and lakes further upstream.
“There are six dams past (Milltown Dam) to pass to reach the (multiple) ponds and lakes,” Almeda said. “It’s one thing to get the fish population up, but reaching additional habitat is (the next challenge).”
Millar said scientists in Canada and the United States share information to determine how many alewives should be the target for the St. Croix. The latest estimates suggest the St. Croix system can eventually support up to 50 million alewives upstream of the Milltown dam, he said, as long as spawning runs continue to grow as they have in recent years.