The Birds and Bees of Browns in the Eastern Sierra
A Peek at the Life Cycle of High Sierra Trout
When it comes right down to it, trout aren’t all that different from people—especially when it comes to the way we reproduce. They do, after all, call pictures of anglers holding trout “fish porn.”
Indeed, it turns out that the biggest distinction between the way our two species reproduce is that while trout partake in every aspect of the process in water, humans only sporadically have water involved; with things like water births, waterbeds and the occasional alcohol-induced incidents in hot tubs.
Trout Have to Listen to Their Hormones
“Just like humans, trout have to listen to their hormones and when they get the urge, they can’t fight it,” explained Dr. Tom Jenkins, a gray-bearded, semi-retired fisheries biologist who’s lived in (and studied the trout of) the Eastern Sierra for close to 40 years.
“Biology matters,” declared Dr. Tom, who earned his PhD from UCLA and was a longtime member of the Advisory Board for the former Eastern Sierra Hatchery Foundation. “Knowing when spawning takes place matters to those who manage the fisheries, and to those who fish them.”
While humans have all kinds of wacky names for the first step in the reproductive process (i.e. “Making love,” “Bumping uglies,” Pulling the goalie”), for trout the first step is simply called “spawning.” And as is sometimes the case with human copulation, for trout it’s often more about being in the right place at the right time than it is about romance.
Both brown and brook trout (Dr. Tom’s area of fishy expertise) spawn in the fall, whereas, rainbows, cutthroats and golden trout tend to spawn in the spring. For the typical brown trout—first brought to the Eastern Sierra from Central Europe more than a century ago—the process begins in late September or early October, when mature males move into the spawning grounds to anxiously await the arrival of their potential mates.
The spawning grounds are actually the most important aspect involved in trout reproduction. “The real constraint on reproduction is having enough space; good gravel for eggs to be placed and space for fingerlings to grow,” Dr. Tom explained.
Most Brown Prefer to Reproduce in Moving Waters
Even if they spend the rest of their lives in lakes, browns (like most trout) prefer to reproduce in the moving waters of creeks and rivers. Browns also are known for their fidelity—though they are only faithful to places, not partners.
When the female brown trout arrive in the spawning grounds, or rearing areas, she’s already carrying her lifetime’s compliment of eggs, in sort of the same way that women do. Once she finds a suitable locale, the female will use her tail to dig out a nest in the gravel, usually between six inches and a foot deep. It’s at this point in the process when the spawning grounds really start to resemble watering holes in the human world.
“The females come up and they choose the actual place where reproduction will occur, and then the males sort of come in and buy `em drinks,” as Dr. Tom described it.
The female usually requires some serious wooing, or at least a drink or two, before she’s ready to release her eggs. Once the female has picked and prepped her spot, a male will approach her, usually a big and brilliantly colored one, and he’ll basically start showing off. The male brown trout can often go through a significantly change in color and can develop a hook jaw to help them attract females, but unlike other salmonids—who are essentially starting to rot during spawning—trout don’t die after rearing.
Shortly after the male trout cozies up next his prospective mate, he will once again act a lot like his human counterparts and will start to vibrate against the female to help get her in the mood. As is also the case with humans, sometimes this works, sometimes it doesn’t.
Trout Don’t Have Bars, but They Basically Do What People Do
“People do just what trout do. Sure, trout don’t have bars, but they basically do what people do, just shut off their frontal lobes, show off their muscles and try to get after it,” Dr. Tom said.
Eventually, the fickle female will decide that the big moment has arrived. She will then arch her body together with her selected mate in the shape of an S and will release her eggs as the male releases his milt. The instantly fertilized eggs will then fall to the nest, which the female will bury under gravel. At least that’s the idea.
Often times, just as the big moment finally arrives, a smaller male, referred to as a “sneaker” will slip in and deposit his milt without even bothering to buy any drinks or do any wooing. Brook trout, much like wily and unscrupulous bartenders, are considered the masters of the “sneak.”
“Each trout is only out for itself,” Dr. Tom said.
The female will then move upstream and repeat the process, creating what’s called a “trout redd.” Each time she digs up a new nest, it helps bury the previous one and she’ll keep going until she’s either out of suitable gravel or out of eggs.
After copulating the spawners, naturally, are pretty hungry and tired, have lost interest in one another and may feel like having a smoke. But their part of the life cycle is complete. Some will stay in the area, others will look for more promising water.
Under the gravel, the future trout will develop in their eggs for a few months before hatching into what are called “alevins” or “sac fry.” The fry can be as small as 18 millimeters and will feed on their sac until it’s gone—and that’s when life gets really interesting for the mini-fingerlings.
Sometime in the spring, the tiny trout, or “young of year,” will begin to emerge from the gravel in search of food just slightly lower in the food chain than they are.
“It’s the most dangerous time in the trouts’ lives. Everybody wants to eat them and there’s lots of competition for food, so it’s easy for them to starve to death,” Dr. Tom explained.
Trout lucky enough to survive will then spend the next two years in the stream, even if their parents came from a lake, before these “juveniles” finally get going down stream in search of adventure, or better feeding grounds.
“Juvenile trout are a lot like juvenile people, except juvenile people can still reproduce,” Dr. Tom joked.
By their third birthday, as the leaves once again begin to fall, the brown trout are now ready to play their roles in the reproduction process. Browns, however, don’t spawn ever year, and they can also get too large for the spawning grounds—or to make it through the “bottle necks” that all moving water (and major highways) seem to have. So the biggest browns, sometimes called “God’s fish” in the Eastern Sierra, will retire their “vents,” as a trout’s reproduction organs are called.