coastal rainbow trout and Columbia River redband trout populations also display reddish or pink throat markings. At maturity, different populations and subspecies of cutthroat trout can range from in length, depending on habitat and food availability. Sea-run forms of coastal cutthroat trout average . The length and weights of mature inland forms vary widely depending on their particular environment and availability of food. Stream-resident fish are much smaller, , while lacustrine populations have attained weights ranging from in ideal conditions. The largest cutthroat trout subspecies is the Lahontan cutthroat trout . These fish average in small streams and in larger rivers and lakes. In ideal environments, the Lahontan cutthroat trout attains typical weights of . The world record cutthroat trout is a Lahontan at and . Lifecycle Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms. They are native to the alluvial or freestone streams typical of tributaries of the Pacific Basin, Great Basin and Rocky Mountains. They spawn in the spring, as early as February in coastal rivers and as late as July in high mountain lakes and streams. Spawning begins when water temperatures reach . Cutthroat trout construct a redd in the stream gravel to lay eggs. The female selects the site for and excavates the redd. Females, depending on size, lay between 200 and 4,400 eggs. Eggs are fertilized with milt (sperm) by an attending male. Eggs hatch into alevins or sac fry in about a month and spend two weeks in the gravel while they absorb their yolk sack before emerging. After emergence, fry begin feeding on zooplankton. Juvenile cutthroat trout typically mature in three to five years. Lake-resident cutthroat trout are usually found in moderately deep, cool lakes with adequate shallows and vegetation for good food production. Lake populations generally require access to gravel-bottomed streams to be self-sustaining, but occasionally spawn on shallow gravel beds with good water circulation. Cutthroat trout naturally interbreed with the closely related rainbow trout, producing fertile hybrids commonly called "cutbows". This hybrid generally bears similar coloration and overall appearance to the cutthroat trout, usually retaining the characteristic orange-red slash. Cutbow hybrids often pose a taxonomic difficulty when trying to distinguish any given specimen as a rainbow or cutthroat trout. In addition, cutthroat trout may hybridize with , the Gila trout and , the Apache trout in regions where their ranges overlap.