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Nature Notes: Brook Trout

Ed Robinson
April 11, 2022

This is one of 40 wildlife essays found in Ed Robinson’s second book, Nature Notes from Maine: Puffins, Black Bears, Raccoons & moreClick here for details.

The mid-September day was perfect for fishing; overcast, upper 50’s, light breeze, no mosquitos, swamp maples in bright red dress.  The fly was a floating elk hair caddis, one of the most productive flies in any Maine angler’s box.  The stream was small but scenic, winding through a quiet meadow 20 miles east of Greenville.  For once my cast was good, the fly landing inches away from the streambank where it was undercut by the flow.  No sooner had the fly dimpled the surface than the fish inhaled it then leaped from the water with wild abandon, trying to throw the hook that ruined all thought of an easy meal.  Alert to the strike I held the rod tip high to keep the line tight in hopes of landing the fish.

It will be a long time before I forget the sight of that fish as it finally came to the net.  Any fly-caught trout is a trophy in my book, but this was a wild brook trout in peak autumn spawning colors.  The orange belly grabbed my eye, as did the bright white stripes along the jaw and the leading edge of the lower fins.  A mature male, the brookie carried the sharp snout and hooked jaw of a fish ready to find a mate and spread his genes to the next generation.  Having removed the hook without touching the fish I let it rest in the submerged net while I admired the bright spots on the flanks that cause some folks to call the fish a speckled trout.  After a minute the trout regained its strength and flashed away to cover, no doubt wiser for the encounter.     

Photo by Devin Davenport, iStock.

Sportsmen and women journey to Maine from all over the world to experience the fine sport available in our beautiful state.  While our waterways boast an impressive collection of game species a hefty brook trout is often at the top of the bucket list for visitors.  Maine has more watersheds with wild brookies than all the other eastern US states combined.  Of roughly 32,000 miles of rivers in the state Maine’s Department of Inland Fisheries & Wildlife (IF&W) estimates that 70% support principal brook trout fisheries.  Surveys have confirmed brook trout living in more than 1,500 of our lakes and ponds.  These fish are esteemed on the plate, but they also are responsible for a sizable contribution to tourism and the associated economic benefits around Maine.  So valued is the brook trout here that in 2005 the state legislature designated it as a State Heritage Fish. 

Beauty is in the eye of the beholder but many would agree that a mature brookie is one of the most spectacular salmonids in the world.  Their color scheme begins with dark green on the back changing to light green on the sides.  Marbled light yellow to green lines known as vermiculation are found on the upper half of the fish including the dorsal, adipose and caudal (tail) fins.  The sides of the fish display distinctive reddish spots ringed with light blue.  The lower fins are mostly orange with black and white stripes on the leading edges.  The belly is light colored except for spawning males when it becomes bright orange.  Variation in appearance is influenced by genetics and primary food sources. 

Salvelinus fontinalis is not a true trout, but a member of the char family along with lake trout (called togue in Maine), Arctic char, bull trout, and Dolly Varden.  Ancestors of the brook trout were here millions of years ago and the fish is considered a native species across a large swath of the northeastern US, the Maritime provinces and the river systems of Canada’s James and Ungava Bays.  Populations were also distributed as far west as Manitoba, some of the Great Lakes states, and as far south as Georgia.  In Maine you will find brook trout in freshwater lakes and ponds, along with streams that run to the sea.  The brookie is capable of living an anadromous lifestyle, with fish known as “salters” starting life in a stream, migrating into salt water for a few months, then returning to the stream of its birth to spawn.  Because of its reputation as a game fish the brook trout has been introduced to rivers far afield in South America, Asia, Iceland, Europe and New Zealand.

Brook trout spawn from late September to November depending upon their environment.  After running upstream in their birth rivers females or “hens” will select a quiet spot on the river bed where water moves through a gravel bottom.  Brookies will also spawn in ponds or along lake shores with springs flowing through gravel, a condition that thankfully occurs in the pond by my old cabin. The hen rolls onto her side and uses her tail to create a shallow depression or “redd” in the gravel, sweeping away silt or woody debris.  Male or “cock” fish begin courting actions, swimming around the hen and attempting to chase away other males.  As the hen settles in to begin expressing between 500 and 5000 eggs one or two males crowd into the redd and begin to eject their milt (sperm), thereby fertilizing the eggs.  The eggs are slightly heavier than water and “sticky” so they settle to the bottom and adhere to the gravel.  The hen completes her part in the breeding cycle by finning gravel back in place to cover the eggs so they will not be washed away or eaten by numerous predators. 

The eggs remain on the gravel all winter, absorbing oxygen from the water.  When conditions are right in February or March the tiny fish (known as “alevins”) emerge from the eggs but remain in place until they have absorbed the nutritious yolk sac.  Once they leave the redd the small trout (now called “fry”) must quickly find cover in order to survive and feed in order to gain size and strength.  Over time they will migrate downstream until they find a suitable location for their growth phase of two to three years. 

The key success criteria for brook trout include clean, oxygenated water no warmer than 750 F, adequate food supplies throughout the year, and security cover to protect the fish from predators.  As a cold-blooded creature brookies are most active between 500 – 650 F although they will feed in winter as water temperatures fall nearly to freezing.  Brook trout are opportunistic feeders, consuming a highly varied diet throughout the year including all stages of aquatic insects, terrestrial insects that fall into the water, small fish, amphibians, crustaceans, invertebrates, and small mammals like mice when available.  There are many predators in search of small fish like brook trout, ranging from larger fish to great blue herons, ospreys and belted kingfishers, mink and river otters.  One day on the Kennebago River I had mixed feelings about being out-fished by a sleek, brown mink!  

In the heyday of Maine’s sporting camps (1880 – 1920) it was not uncommon for fishermen to land brook trout of six, eight, even ten pounds.  In an era when the legal daily bag limit was up to 25 pounds too many of those old brookies were killed for the wall or the frying pan.  While there are historic reports of fish as large as 15 pounds the certified state record brook trout is a nine pound fish caught on January 8, 2010 in Mousam Lake.  The world record is a 32 incher weighing over 14 pounds caught in 1916 in northern Ontario. 

Today most wild brookies landed by stream fishermen range between 6-14 inches long.  An angler lucky enough to catch a brook trout over five pounds has plenty of bragging rights.  In the harsh environment of northern Maine rivers most fish live no longer than three to six years but in warmer lakes with more reliable food supplies exceptional fish up to 20 years old have been recorded.  While the current bag limit is five fish per day in northern Maine, most fishermen consider the brookie too valuable to drop in a frying pan so they voluntarily catch and release the trout.  IF&W plays an active role in managing brook trout populations while supporting fishing in many waters by stocking up to 600,000 hatchery raised trout each year.     

Sadly, the hand of man has greatly reduced the range and population of brook trout in the last 200 years thanks to over-fishing, dam building and over-harvesting of timber along with industrial, municipal and agricultural pollution.  Now that acid rain is less prevalent than before the federal Clean Water Act of 1972, the major threat to brook trout is illegal introduction of competing predator fish like northern pike and smallmouth bass to trout waters.  IF&W actively discourages this practice with public education and regulation, sometimes resorting to poisoning historic trout ponds to remove all fish, then restocking wild strain brookies.  The long-term effects of ongoing human development and climate change will certainly play a major role in the future of the brook trout.  The goal must be to minimize the loss of critical habitat, to improve water quality and to protect wild brook trout populations by all possible means.  IF&W, timber companies, land trusts and conservation groups like Trout Unlimited all have a role to play with our support. 

April 2022