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Brook Trout The brook trout, Salvelinus fontinalis, is the smallest of the native salmonids of Vermont, and is also called the “squaretail.” It is adapted to the widest variety of habitats of all of the trout species and lives in tiny, infertile, steep-sloping mountain streams; larger rivers with constant cool-water supplies; gently sloping bog streams; beaver ponds; and clear, cold lakes. Brown Trout The brown trout, Salmo trutta, is one of the trout species in Vermont that is not native. It was introduced to Vermont during the late 1800s and there are now spawning populations in most of the drainage basins in the state. They are commonly found in rivers and streams. Fish and Wildlife personnel carefully choose the lakes and ponds in which they stock brown trout, as the fishtend to grow quite large in these habitats and eat many smaller fish, includingother stocked t Rainbow Trout Native to the West Coast and introduced to Vermont in the late 1800s, rainbow trout (Oncorhynchus mykiss) are the most habitat-sensitive of the trout species and are stocked and bred extensively in state fisheries. Rainbow trout will live in high- to moderate-gradient streams and rivers, as well as cold lakes. They are very sensitive to water pH levels and do not do well in acidic conditions. Physical Description The most distinguishing feature of the brook trout (or wild “brookie”) is its adipose fin, or small fin on the back located directly in front of the tail. This characteristic is shared only by other salmonids and no other fish species. Brook trout have a brilliant orange belly which is particularly apparent in spawning males, and is thought by many to be our most beautiful fish. Its dark olive-green back is laced with darker worm-like markings. Red spots with bluish halos highlight the body. The lower fins are pink or reddish with their leading edges margined in white. The brown trout is a golden brown on top, shading to a lighter tone on the sides and silver or dusky yellow below. The back, sides, and dorsal fin are marked with large dark spots outlined with pale halos. Reddish-orange or yellow spots also dot the sides. The rainbow trout is silver gray to dark greenish with a pinkish or reddish streak along the sides. The tail is covered with rows of dark spots. Small spots also pepper the head, sides and belly. Food Items Brook trout eat whatever they happen to see, although they prefer drifting bugs, or aquatic macroinver-tebrates (e.g., stoneflies, mayflies, caddisflies), to bottom-dwelling bugs when available. Larger individuals may feed on smaller fish, especially in lakes. The brook trout is more of a daytime feeder than either the brown or rainbow trout. Brown trout are opportunistic feeders, but are perhaps more selective than other trout species. Aquatic and terrestrial insects make up the primary food source of brown trout that are less than ten inches in length. As they become larger, they shift more to fish and crustaceans. Mature brown trout in streams feed primarily at night, while those in lakes are more likely to feed during daylight hours. Rainbow trout consume a wide variety of foods, depending on availability. Stream populations tend to prefer drifting aquatic and terrestrial insects while lake populations may feed more on microscopic animals and bottom-dwelling organisms such as worms, crustaceans, aquatic insect larvae, mussels, clams, and crawfish. They will shift more to smaller fish as they reach about 12 inches in length. Habitat Water temperatures are the most important factor in brook trout habitat. It thrives in water temperatures of near freezing (32° Fahrenheit) to about 65° F. Temperatures between 55° F and 60° F are most ideal. Although the brook trout will tolerate brief periods of temperatures up to 72° F, they will die if exposed to temperatures of 75°F for only a few hours. Brook trout also tolerate a wider range of pH levels than brown trout or rainbow trout, from the extremely low level of 3.5 to a high of 9.8 in laboratory studies. In natural conditions, a more realistic range is between 6.5 and 8.0. Optimal brook trout habitat in streams is characterized by:
In lakes and ponds, brook trout tend to inhabit shallow, spring-fed areas less than 15 to 20 feet in depth. During periods of hot weather, they will seek shallow, cold-water pools of water that well up from the ground rather than retreat to colder depths. The brown trout typically inhabits the lower reaches of cold-water streams, characterized by deep, slow-moving pools and runs. It also thrives in larger lakes of sufficient depth to maintain cool water temperatures year round. The brown trout is more tolerant of warm water temperatures and pollution than other species of trout. As with other trout species, water temperature is a major limiting factor for brown trout. Optimum temperatures range from 53° F to 66° F, although they can tolerate temperatures near 80° F for short periods of time. Brown trout tolerate pH levels from 5.0 to 9.5 but the optimal range is between 6.8 and 7.8. Optimal brown trout habitat in streams is characterized by:
In streams, rainbow trout prefer water temperatures similar to those favored by brown trout, from 54° F to 66° F, while lake-dwellers select waters between 45° F and 64° F. The maximum tolerable water temperature is 77°F, but some populations may be able to withstand temperatures in the low eighties for short periods of time. Rainbow trout are more sensitive than other salmonids to very high or low pH levels, especially acidic conditions. A pH range of 6.5 to 8.0 is considered optimal and adults can tolerate levels from 5.5 to 9.0. Natural reproduction is not successful in waters with pH less than 6. Optimal physical stream habitat for rainbow trout consists of the following:
Abundance Providing habitat conditions are suitable and competition with other species is minimal, wild brook trout populations are found in most streams and in many ponds throughout Vermont. It is the one trout species most likely to be encountered in small headwater streams and beaver ponds. In larger waters, brook trout often coexist with brown and/or rainbow trout, or in some instances have been replaced by these non-native trout species. Even though the brook trout is typically identified with streams, wild populations do exist in some cold-water lakes and ponds. Optimal lake and pond habitat has clear, cold, deep water. In addition to spawning in feeder streams, spawning may occur in the lakes where gravel deposits associated with spring-water upwellings occur. There are not many lakes and ponds with wild brook trout populations in the state, and the few that exist are in remote places in the Green Mountains and the Northeast Kingdom. There are, however, small beaver ponds throughout the state with wild brook trout populations. Stocking allows fishing in lakes and ponds that are otherwise not capable of supporting wild trout populations. Many of Vermont’s lakes and ponds are almost ideal habitats for brook trout, except that they are unable to support natural reproduction due to inadequate spawning areas and are also are inhabited by other competitive fish, which eat smaller brook trout. If the brook trout cannot reproduce and survive on its own, it will have to be raised elsewhere and brought to the lake or pond when it is big enough. The public lakes and ponds of Vermont are stocked with fish raised in state hatcheries. More brook trout are reared in the state hatchery system to stock public waters than either brown trout or rainbow trout. Waters that have nearly ideal habitat conditions are sometimes managed for put-grow-and-take fisheries; others with less suitable habitat are stocked with catchable-size trout on a put-and-take basis. The brown trout was introduced to Vermont during the late 1800s and the species soon established a firm foothold in all the major drainage basins. It frequents many of the streams and rivers also occupied by brook trout and rainbow trout. Brown trout have a preference for the deeper, slower and more fertile downstream river areas. Natural spawning populations are common to most drainage basins in the state, nevertheless, many of these waters are also stocked with catchable-sized brown trout to supplement the wild resource and improve fishing opportunities. The establishment of wild brown trout populations in a large number of waters has often been at the expense of the native brook trout. For example, the Battenkill in the southwestern region of the state was historically a brook trout stream, but the brown trout, introduced around 1926, have largely replaced the native species. On the other hand, the establishment of brown trout populations has given anglers another type of trout to catch in Vermont. The brown trout is also well adapted to many lowland river areas, to which brook trout are not well suited. Brown trout often grow to trophy sizes in these waters. Brown trout populations in lakes and ponds are relatively limited in Vermont. Even though brown trout adapt well to certain pond and lake habitats, Vermont Fish & Wildlife has decided to only stock rivers and streams. The problem is that brown trout have a tendency to accumulate in abundance in lakes and ponds because they compete with other trout species and withstand fishing so well. They are also a problem in lakes and ponds because they tend to grow to large sizes and then feed heavily on other fish, including recently stocked smaller trout. These are not problems when lakes and ponds are managed for either brook or rainbow trout. Rainbow trout were also introduced into Vermont waters beginning in the late 1800s. Over the years they have become an important component of the state’s fisheries in both river and lake habitats. These fisheries exist today as a result of natural reproduction, stocking, or a combination of the two. However, while brown trout eventually established wild populations throughout much of the state, wild rainbow trout populations are noticeably absent from the large watersheds of southeastern Vermont. Even though rainbow trout have been, and continue to be, stocked extensively in this region, these waters characteristically have low alkalinity, a condition that does not support rainbow trout reproduction. Consequently rainbow trout fisheries in the southeast region are dependent on stocking. Notable exceptions include numerous small, lowland watersheds draining into the Connecticut River. It is believed that these small watersheds provide spawning habitat for the Connecticut River population. Typically these small spawning streams have drainage areas less than 20 square miles. Lake populations of rainbow trout in the Northeast Kingdom are the only areas in Vermont that are supported entirely or in part by natural reproduction. As noted for stream populations, alkalinity is also a factor limiting the distribution of wild populations in Vermont lakes and ponds. The inability of many of the state’s lake and pond populations to be supported to some extent by natural reproduction can also be attributed to the lack of suitable spawning habitat. Lake-residing fish must have access to streams offering suitable spawning and nursery habitat in order to maintain a wild population. In the absence of quality spawning streams, most lake populations must be maintained by stocking. Predators The main predators of Vermont trout species are birds, people, other fish, salamanders, raccoons, otters, and mink. Birds that eat fish include Merganser ducks, heron, kingfisher, loon, osprey and eagles. Aquatic salamanders prey off brook trout eggs and perhaps fry. Life Cycle In Vermont, brook trout are of ten slow growing and short lived, rarely exceeding 3-4 years of age. Many headwater mountain streams rarely produce brook trout larger than 6-7 inches. In more productive waters, especially lakes and ponds, they can live longer and achieve maximum lengths of over 20 inches and weigh more than five pounds. The age at which brook trout are able to reproduce varies among populations. Males may mature as early as their first year of life, but usually mature in their second year. Females mature in their second or third year. Brook trout generally migrate to spring-fed areas of headwater streams to spawn when water temperatures decline to 40° F to 50° F, usually in late-September through November, although the migrations are not as obvious as with other trout species. Some individuals may spend their entire lives in a small area of a stream if suitable habitat exists. Lake- and pond-dwelling populations migrate into tributaries or can also successfully spawn on lake-bottom areas of spring-fed pools. Spawning occurs at water temperatures of between 40° F and 50° F. The female excavates a shallow hole, also called a redd, over a groundwater upwelling or the tail of a pool, in gravel. The male fertilizes the eggs as they are deposited, and the female follows and covers the eggs with gravel. Eggs may be deposited by one pair of trout over a series of small redds. In Vermont, eggs spend the winter in the gravel. Incubation takes from about 45 days at 50° F to 165 days at 37° F. Newly hatched fry remain in the gravel until their yolk sac is absorbed. Then they come out of the gravel and live in a shallow area of the stream, with low water speeds and with rocks big enough to resist shifting. When they grow into the juvenile stage, they will move into swifter riffle areas. Brown trout usually live for 5-6 years, although ages of eight and nine years are not uncommon in waters that aren’t frequently fished. They generally grow at faster rates and achieve larger sizes than brook trout or rainbow trout. In Vermont streams, brown trout tend to reach 5-9 inches after two years, 8-11 inches by their third year, and 9-14 inches by their fourth year. Growth rates in lakes are typically faster, with three-year-old brown trout reaching 11-18 inches and four-year-olds averaging 13-21 inches in length. Relatively few brown trout older than four years have been collected in fishery surveys, but every year anglers catch some very large fish. In Vermont streams, the male brown trout matures at two to three years of age and the female matures one year later. Some lake-dwelling strains may not mature until the fourth or fifth year. Spawning typically occurs from late October through December, when water temperatures reach an optimum range of 44° F to 48° F. Lake populations must have access to suitable tributary streams to reproduce. They sometimes migrate considerable distances to reach tributaries or headwaters with well-oxygenated gravel at the tail of pools. Although brook trout will exclusively select groundwater upwellings for spawning sites, these areas may or may not be used by brown trout. The female digs a well-defined redd or shallow hole, which takes several days. When she is finished, one or more males will join her to complete the fertilization of her eggs. Optimal incubation temperatures range between 36° F to 55° F, but tolerable levels range from 32° F to 59° F. Like brook trout, brown trout eggs overwinter in the gravel. Incubation times vary from 148 days at 35° F (typical of Vermont streams) to 30 days at 57° F. Young fish, called fry, emerge from the gravel after absorbing their yolk sacs. They disperse quickly, immediately establishing territories in shallow, low-velocity pools with rocky surfaces. This habitat is also preferred by larger juvenile brown trout, which may force the fry to the edges of pools and riffles on smoother surfaces. Life expectancy of rainbow trout is highly variable over its range but is generally three to five years, sometimes longer in lake populations. Growth rates in Vermont streams are similar to those of brook trout, but they tend to grow larger due to their greater life span. They generally reach 4-6 inches after two years, 6-9 inches by their third year, and 8-12 inches by their fourth year. As with the other species of trout, rainbow trout populations in lakes grow faster—four-year-old fish attain lengths of 13-17 inches or more. Rainbow trout in streams generally become mature during their second or third year, whereas lake fish tend to mature later. They spawn almost exclusively in streams. Unlike brook trout and brown trout, most rainbow trout spawn in the spring (usually March through May in Vermont) triggered by rising spring flows and warmer water temperatures. Selective breeding in hatcheries has produced strains that spawn in the fall months or other times of the year. When the female is ready to reproduce, she digs a small hole, usually in the fine gravel at the tail of a pool. Water temperatures for incubation range from 45° F to 54° F. The eggs will hatch in 28 to 49 days. Fry emerge from the gravel about two weeks after hatching and congregate in schools in the calm areas near the edges of the stream channel. After several weeks, the fry grow more territorial and the schools disperse. By the end of their first year, juvenile rainbow trout move into the more swiftly flowing riffle areas. History The brook trout is native to Vermont lakes, streams, rivers, and ponds, along with the lake trout and Atlantic salmon. Brook trout were impacted by the introduction of brown trout and rainbow trout and yet still thrive throughout the state. Native to Europe, the first recorded introduction of the brown trout was in 1892 in Bennington, Vermont. Following their introduction, the species soon established a firm foothold in all major drainage basins in Vermont. There are many wild, naturalized populations, as well as stocked, throughout the state. Native to the West Coast of the United States, the first recorded introduction of the rainbow trout was in 1886 in Lunenburg, Vermont. Naturalized populations now exist in most drainages in Vermont, with the exception of the southeast region of the state. Here the streams generally have low alkalinity or acidic conditions, to which rainbow trout are particularly sensitive. Rainbow trout populations are maintained by stocking for this region of the state and in several lakes and ponds where spawning habitat is lacking. Management Efforts In Vermont, over 180 lakes and ponds and 3,800 miles of streams and rivers are managed by the Vermont Department of Fish & Wildlife for one or more trout species. The Department must decide whether or not to stock an area, where to set length and creel limits and gear restrictions, and when and where to allow or not allow fishing by anglers. The general areas the state considers in management are:
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Additional Information: Vermonts Wild Brook Trout | |