Most outdoor folks are aware that the breeding season for white-tailed deer, commonly referred to as the "rut," is fast approaching. Rubs and scrapes are the first signs of this annual ritual, as bucks stake out their territory and the mating rights within it.
The peak of the breeding activity usually takes place around early to mid-November. Hordes of bowhunters eagerly anticipate this period because of the increased deer movement during the daylight hours it produces. Spurred by a strong mating instinct, bucks will tend to abandon much of their natural caution in pursuit of does, so during the rut, even the wiliest, most elusive old buck can sometimes act dumber than a box of rocks.
Deer, however, aren't the only creatures that are engaged in the procreation of their species during the fall. Trout also spawn this time of year. In Pennsylvania, hundreds of streams are stocked with trout to provide fishing opportunities, but many streams throughout the state also support sufficient natural reproduction of trout to produce a self-sustaining fishery. Waters capable of producing ample populations of wild trout are special and highly valuable resources.
For me, one of the pleasures of fishing in the fall is having the chance to watch trout engaged in their spawning activities. Both brook and brown trout are fall spawners. Brook trout, of course, are the only species of trout actually native to Pennsylvania. Brown trout were imported from Europe, and rainbows were transplanted here from their native range along the Pacific coast of North America. Rainbows are spring spawners, and rarely reproduce successfully in the wild on this side of the continent. In this area, I have observed rainbows involved in spawning behavior during both spring and fall on Spring Creek in Centre County and Spruce Creek in Huntingdon County.
Wild brook trout now exist mainly in smaller headwater streams, and these fish spawn in September and October. Brown trout typically spawn a little later, usually during October and November, although I've seen browns spawning into January on some limestone streams. Brown trout are highly adaptable, so any unpolluted waterway that stays cold enough to support trout year-round will probably harbor some wild brown trout.
The female trout selects the actual spawning site, which must meet some specific requirements. Most spawning take place in relatively shallow water, typically a foot or less, with some amount of current flow. A bottom composition with plenty of smooth gravel in the right size is most important - pea-sized for smaller fish up to the size of a golf ball for bigger trout.
After the female finds a suitable spawning site, she will begin to excavate a shallow nest known as a "redd." To do this, the fish rolls on its side and quickly beats its tail up and down to dislodge the gravel and create a shallow depression in which to deposit its eggs. Between the time the female arrives at the spawning site and when she begins to excavate the redd, one or more males will show up to court her. In the case of multiple suitors, each will attempt to chase off the other until one of the males has asserted its dominance.
When the redd is finished, the female positions herself over the egg pocket that was created with the male close beside her. In synchronization, she releases eggs while the male sprays them with sperm, and the fertilized eggs settle into the nest. Any eggs that miss the mark will be swept away by the current and quickly eaten by trout or other fish.
The number of eggs a female produces is related to the size of the individual fish. Wild brook trout are likely to be somewhere between 6 to 14 inches and will produce 100 to more than a 1,000 eggs. A small brown trout can produce about 600 eggs, while a large fish weighing several pounds or more could yield 3,000 or more eggs.
After depositing its eggs, the female again uses its tail to cover them with a thin layer of gravel for protection. That is the final bit of care either parent provides for their progeny. The male departs soon after the spawning act and will mate with other receptive females if possible. The female will stay at the nest site for a day or so, mostly for rest and recovery from the stress of spawning, before returning to its home pool.
The incubation period for trout eggs is directly related to water temperature and therefore varies widely in the wild. At optimal temperatures of 50 degrees, trout eggs can hatch in as soon as three week; in the average temperatures found in our Pennsylvania streams during late fall and early winter, most trout typically hatch in January and February.
In spite of the large numbers of eggs a single female trout might produce, only a small percentage of each new generation of trout will survive to see an angler's offering. And fewer still will make it to trophy size. That's why most dedicated fishermen practice catch and release when it comes to wild trout. They are truly special fish.