Gaspereau fish population rebounds in St. Croix River
Fish count reveals 93,470 gaspereau returned to river in 2015, four times the 10-year average
More than 93,000 gaspereau returned to the St. Croix River this year, making it the highest fish count in 17 years and four times the 10-year average.
The Milltown fish count for 2015 revealed 93,470 gaspereau migrated up the St. Croix River to spawn this year and researchers believe it's a sign the population is rebounding.
"I'm reading the signs as optimistic.
"In 1998 there were 177,000 fish, but previously there were hundreds of thousands, millions of gaspereau in the St. Croix system," she said.
The St. Croix River was reopened to gaspereau in the spring of 2013.
Prior to that, the government of Maine had blocked the river to prevent the fish from migrating to their spawning grounds since 1995. State legislators claimed they were protecting the smallmouth bass, an introduced fish favoured by anglers.
The fish population dropped significantly since the state's actions.
In 2014, researchers counted 27,000 fish at the Milltown Generating Station in St. Stephen. The year before, only 16,677, said Pond.
But Pond said other factors might be behind the sudden rebound.
"We had a relatively good runoff last year in terms of the spring flow," she said.
"We didn't have long, vast high water for a long time. And we had some hot, sunny weather. That's when the gaspereau like to move."
Fish counted by hand
Pond said fishway engineers from the United States and Canada also made adjustments to the dam's fish ladder this year, which made it easier for gaspereau to jump from the river into the ladder.
"That seems to have worked," she said.
The population has bounced back so well, Pond says researchers will have to change the way they handle their annual count.
"The numbers have been so small in recent years, we've been lifting them from the net. We open the cage, get inside it, and lift every single gaspereau out and count them as we put them up the river," she said.
"So every one of those gaspereau have been hand-counted this year."
Next year researchers may extrapolate from a partial count, said Pond.
"Before 1999 when we had all these numbers in the hundreds of thousands, you'd watch the fish jumping over a white board for 10 minutes every hour," she said.
"Every time fish went upriver you'd click and then you'd multiply it out."
Gaspereau is native to the river and is an important prey for larger groundfish like cod and halibut when it returns to the ocean.