Crash of smelt inhabitants might endanger Sebago Lake’s famed landlocked salmon
Sebago Lake has lengthy been one of many premier landlocked salmon fisheries in Maine. It’s certainly one of solely 4 waters within the state to which the fish are native.
However there may be concern amongst anglers and biologists alike that Sebago Lake’s native salmon, and the rainbow smelt inhabitants that feeds them, are in hassle.
The state’s stocking of lake trout, pure fluctuations in bait fish abundance, adjustments in angler conduct and the unlawful introduction of freshwater alewives and Northern pike have conspired to create a quickly altering fishery within the state’s second largest lake.
Because of this, the variety of smelts, the first forage of salmon and lake trout, are once more approaching historic low ranges. That has left salmon and lake trout combating for survival.
Jim Pellerin, regional fisheries biologist for the Maine Division of Inland Fisheries and Wildlife, mentioned Sebago’s smelt inhabitants is just not at its lowest stage ever, however his observations of salmon situation point out it has solely been worse two or thrice within the final half-century.
Sebago constructed its popularity on producing trophy salmon through the late 1800s and early 1900s, earlier than the inhabitants was decimated by overfishing. Stocking efforts by DIF&W ultimately restored numbers, together with these of native fish.
Then, it was a man-made scenario that took an enormous toll on Sebago’s fisheries.
“We virtually misplaced the salmon and smelt again within the ’60s through the DDT period,” Pellerin mentioned of the pesticides. “So we’ve recovered some from some fairly unhealthy conditions earlier than and hopefully we are able to do it once more.”
The following risk to native salmon got here when, below public strain, the state lastly agreed to inventory lake trout, also referred to as togue, in Sebago.
The late Stu DeRoche, the regional fisheries biologist in southern Maine waters on the time, was reluctant to take action, Pellerin mentioned. The division ultimately relented in 1972, hoping {that a} pressure of deep-dwelling lake trout from New York would create a two-story fishery — one through which the salmon would stay increased within the water column, above 40 ft, whereas the lake trout would keep at decrease depths, and the 2 might co-exist.
As a substitute, the lake trout tailored shortly by imposing themselves on salmon habitat, the place they started feasting on smelts — and the salmon themselves. By the early Nineteen Nineties, the lake trout have been in all places.
“As soon as these massive lake trout over 23 inches confirmed up, the salmon grew to become prey,” Pellerin mentioned, conceding that the stocking, in hindsight, had been a mistake.
Nevertheless, Pellerin identified that lake trout fishing grew to become standard amongst anglers and has offered an financial enhance for the world through the years.
To fight the lake trout drawback, the state enacted guidelines permitting anglers to take extra fish. It labored, and the salmon once more flourished.
“In 2013 we noticed the perfect salmon fishing we’d ever seen traditionally, primarily based on the information that we had all the best way again to the late ’60s,” Pellerin mentioned. “Catch charges have been the best we’d ever seen.”
The salmon fishing peaked over the subsequent two years. Roughly 80 p.c of salmon caught within the lake in 2013 have been native fish, in comparison with 25 p.c through the late Nineteen Eighties.
On the identical time, biologists have been conscious that anglers weren’t eradicating sufficient lake trout to keep up the stability of species. In 2012, the state created a brand new slot restrict for lake trout that might defend the biggest and smallest fish.
The thought, primarily based on analysis performed in Idaho, was that the massive lake trout would cannibalize their younger and assist management the inhabitants.
“That regulation mainly overprotected the lake trout,” Pellerin mentioned.
Freshwater alewives have been illegally launched into Raymond Pond round 2007, and located their approach into Sebago. Their numbers shot up concurrently with the salmon resurgence.
Lake trout ate the alewives, that are bigger than smelts. The alewives have been largely too giant for salmon to eat, and salmon that consumed them had issue reproducing.
By 2016, biologists have been seeing salmon decline, whereas lake trout fishing remained sturdy. It was a matter of too many predators and never sufficient prey, and with a purpose to not lose the smelt inhabitants, the variety of lake trout wanted to be decreased, Pellerin mentioned.
Many anglers and fishing guides continued to make use of catch-and-release ways with lake trout and have been preserving solely a small variety of the fish. Lake trout fishing was significantly productive through the winter in years when there was enough ice on Sebago to allow anglers to entry giant areas of the lake.
Pellerin mentioned a bunch of 5 pals as soon as caught 90 lake trout in a span of solely 5 hours.
“I saved telling folks, that’s not sustainable for this lake,” he mentioned. “It was very alarming.”
The division tried to encourage anglers to reap the smaller fish and maintain as many as they might. As a substitute, most of them have been returned to the lake, even after the lake trout inhabitants started to break down.
That hampered the state’s efforts to scale back the predators and assist restore the dwindling smelt inhabitants on which the lake’s two main species rely so closely for survival.
In 2019, the landlocked alewives, which additionally had been competing arduous with smelts for meals, all of a sudden left Sebago in droves for different waters. It’s a dynamic that happens periodically with alewives.
The end result was a big drop within the variety of smelts, which fell prey to lake trout that had misplaced alewives as a meals supply, and a corresponding decline within the landlocked salmon that depend on smelts for meals.
Now, the alewives have begun to come back again, nevertheless it isn’t clear how the lake trout and salmon will reply to that change.
The salmon inhabitants is down 57 p.c since 2013, and lake trout is down between 29 and 33 p.c within the final 5 years, Pellerin mentioned.
Anglers could legally harvest an infinite variety of lake trout, of any dimension as much as 26 inches, however just one per day could exceed that size.
“The lake trout are primarily ravenous, so that they’re not producing as many younger,” Pellerin mentioned, noting the massive variety of lengthy lake trout with large heads and thin our bodies anglers are catching.
Northern pike are one other risk to Sebago’s native salmon. The voracious predators, which may develop to greater than 20 kilos, have been illegally launched in 2002.
Whereas it’s believed the pike have remained primarily in shallow, weedy areas, which isn’t good salmon habitat, they might be focusing on salmon smolts as meals.
Pellerin mentioned pike spawn round ice-out in shallow, flooded grasses. Giant pike have been seen within the Songo River, a key tributary, and so they could stay in these waters lengthy sufficient to choose off wild salmon smolts dropping into the lake.
Anglers additionally goal pike and, as with lake trout, routinely launch them within the hope they are going to get bigger. The state is working with ice fishing derby sponsors to incorporate prizes for essentially the most pike or the heaviest mixed whole weight.
One optimistic for smelts is that fewer salmon and lake trout imply extra smelts needs to be surviving and hopefully reproducing. The state additionally places about 3 million smelt eggs in Sebago yearly. That mixture might enhance salmon and trout.
“We don’t know if we’ve hit all-time low but and when that’s going to begin to flip round,” Pellerin mentioned of the smelts. “They will flip round fairly shortly. We’ve seen it occur earlier than.”
The long-term prognosis for salmon and lake trout in Sebago Lake might be dependent not solely on what’s taking place within the ecosystem, but in addition on whether or not anglers decide to harvesting extra lake trout.
Pellerin mentioned through the Nineteen Seventies, nearly all legal-size lake trout have been harvested. In the present day, there’s a 70 p.c launch fee on these fish.
“My feeling is, both anglers are going to have to vary their attitudes or we’re going to have to take a look at new strategies to attempt to handle these wild, self-producing populations,” Pellerin mentioned.
Whereas unpopular, measures equivalent to mandating that each one lake trout caught have to be killed directly, paying a bounty for each fish caught by anglers, and even industrial netting to take away giant numbers of the fish, which happens in different states, is perhaps a number of the solely methods to tip the stability again in favor of Sebago Lake’s native salmon.
“Lake trout are very tough as a result of they stay perpetually, they don’t have lots of predators and so they eat lots of meals,” Pellerin mentioned.
Salmon, in contrast, have a a lot shorter life span, often lower than 10 years for wild fish. And so they can’t survive prolonged durations with out meals like lake trout can.
Regardless of the entire adjustments and unlawful introductions which have adversely affected the Sebago Lake fishery, Pellerin stays hopeful the state can avert the doubtless catastrophic lack of smelts and native salmon.
“If we’ve obtained that predator inhabitants down sufficient, we could begin to see a shift,” Pellerin mentioned. “The actual problem shifting ahead is discovering a strategy to harvest and maintain these wild populations in stability.”
