The Vermont Management Plan for Brook, Brown and Rainbow Trout Vermont Fish and Wildlife Department January 2018
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The Vermont Management Plan for Brook, Brown and Rainbow Trout Vermont Fish and Wildlife Department January 2018 Prepared by: Rich Kirn, Fisheries Program Manager Reviewed by: Brian Chipman, Will Eldridge, Jud Kratzer, Bret Ladago, Chet MacKenzie, Adam Miller, Pete McHugh, Lee Simard, Monty Walker, Lael Will ACKNOWLEDGMENT: This project was made possible by fishing license sales and matching Dingell- Johnson/Wallop-Breaux funds available through the Federal Sportfish Restoration Act. Table of Contents I. Introduction ......................................................................................... 1 II. Life History and Ecology ................................................................... 2 III. Management History ......................................................................... 7 IV. Status of Existing Fisheries ............................................................. 13 V. Management of Trout Habitat .......................................................... 17 VI. Management of Wild Trout............................................................. 34 VII. Management of Cultured Trout ..................................................... 37 VIII. Management of Angler Harvest ................................................... 66 IX. Trout Management Plan Goals, Objectives and Strategies .............. 82 X. Summary of Laws and Regulations .................................................. 87 XI. Literature Cited ............................................................................... 92 I. Introduction The management of Vermont's fisheries resources is a multi-faceted program consisting of habitat protection, restoration and enhancement; regulation of angler harvest; and species introductions or restorations, which may include the use of artificially reared (i.e. “cultured”) fish. In addition to its many intrinsic values, fishing in Vermont is also important economically. In 2011, an estimated 131.3 million dollars were spent by anglers in Vermont (U.S. Department of Interior 2014). Brook, brown and rainbow trout are among Vermont's most sought after species, comprising three of the top five fish species preferred by Vermont resident open-water anglers (Connelly and Knuth, 2010). These anglers spent over one million days of their open-water angling effort in 2009 pursuing these three trout species in small brooks, larger streams and rivers, and in lakes and ponds throughout Vermont (Connelly and Knuth, 2010). In 1993, the first formal management plan for brook, brown and rainbow trout was adopted in Vermont. The Vermont Management Plan for Brook, Brown and Rainbow Trout provided a comprehensive approach to the management of these important species by integrating public opinion and desires with scientific studies of trout biology and management conducted both in and outside Vermont. The 1993 document served as guidance for fisheries biologists to use in managing Vermont's trout resources and as a public education resource which formally outlined the biological and social justifications of various trout management strategies. This plan serves to update and document the many advances in our understanding of the threats to and management of brook, brown and rainbow trout, as well as changes in public opinion and desires which have occurred since the development of the 1993 “Trout Plan”. The general approach to trout management is described below: It is the goal of the Vermont Fish and Wildlife Department to manage the state's trout resources to support wild trout populations and a diversity of quality recreational opportunities. To meet this goal, it is the policy of the Department to: 1) Place priority on implementing effective habitat protection, restoration, and enhancement measures and harvest regulation in conserving and managing the state's wild trout resources. 2) Utilize cultured trout where management of a recreational trout fishery is justified, but cannot be sustained solely through wild trout management. This plan should be considered a working document, subject to adjustment as warranted by changes in environmental or social pressures on Vermont's trout resources, or advances in fisheries management techniques. 1 II. Life History and Ecology Brook Trout (Salvelinus fontinalis) Habitat The brook trout is adapted to the widest variety of habitats of the trout species (Flick 1991). It inhabits tiny infertile, high-gradient mountain streams, larger rivers with constant cool water supplies, low-gradient bog streams, beaver ponds and coldwater lakes. Warm water temperatures are the most important factor limiting brook trout distribution. While temperatures exceeding 68° F are widely considered to initiate physiological stress, temperatures exceeding 64° F can be detrimental to growth and survival of fry and juveniles (Raleigh 1982, Argent and Kimmel 2014). Optimum growth occurs between 55 and 65° F and it can tolerate brief periods of up to 72° F (Raleigh 1982). Exposure to temperatures of 75° F for only a few hours is usually lethal (Flick 1991). Dissolved oxygen requirements vary with water temperature. Optimum dissolved oxygen concentrations are near saturation levels (Raleigh 1982). Brook trout tolerate a wider range of pH levels than brown trout or rainbow trout. In laboratory studies brook trout have been shown to withstand extremes of 3.5 to 9.8 (Raleigh 1982). In natural conditions a more realistic low pH is around 4.8 (Flick 1991) with an optimum range between 6.5 and 8.0 (Raleigh 1982). Optimal brook trout habitat in streams is characterized by a 1:1 pool to riffle ratio, silt-free rocky substrate, clear, cold spring-fed water with stable flow and temperature, and well vegetated, stable banks, with abundant instream cover (Raleigh 1982). Brook trout tend to prefer areas out of the main flow with relatively low velocities (about 0.5 ft/sec) and overhead cover such as boulders, vegetation and undercut banks (Scarola 1987, Flick 1991). In lakes and ponds brook trout tend to inhabit shallow, spring-fed areas less than 15 to 20 feet in depth. During hot weather periods they are more likely to seek shallow coldwater seeps rather than retreat to colder depths (Flick 1991). Brook trout occupy various habitats during different life stages and times of the year. Brook trout are known to make movements at the local and watershed scale (Davis et al. 2015) for feeding, spawning, and rearing. Age and Growth In Vermont, brook trout are often slow growing and short lived, rarely exceeding 3 to 4 years of age. Many headwater mountain streams rarely produce brook trout larger than 6 or 7 inches. In more productive waters, especially lakes and ponds, they may live longer and achieve maximum lengths of over 20 inches and weigh several pounds. 2 Age at sexual maturity varies among populations. Males may mature as early as their first year of life but usually mature in their second year. Females mature one year later. Spawning Behavior Spawning generally occurs in late September and early October at water temperatures of between 40 and 50° F (Raleigh 1982). Brook trout generally migrate to areas of spring-fed upwellings in streams or in lake and pond substrates (Webster and Eiriksdottir 1976, Witzel and MacCrimmon 1983, Flick 1991).The female excavates a pit or redd over a ground water upwelling or the tail of a pool in gravel of 0.1 to 2 inches in diameter which is well aerated (Flick 1991). The male fertilizes the eggs as they are deposited, followed by the female covering the eggs with gravel. Eggs may be deposited by one pair over a series of small redds (Scarola 1987). In Vermont, eggs incubate in the gravel over winter. Incubation takes from about 45 days at 50° F to 165 days at 37° F (Raleigh 1982). Newly hatched fry remain in the gravel until their yolk sac is absorbed, then emerge and inhabit shallow, low velocity areas with rock of 4 to 8 inches in diameter, sufficient in size to resist shifting. At the juvenile stage, they move into swifter riffle areas (Raleigh 1982). Food Habits Brook trout appear to be opportunistic sight feeders preferring drifting aquatic macroinvertebrates over benthic (bottom dwelling) organisms when available. Larger individuals may feed on small fish at times, especially in lakes (Raleigh 1982). The brook trout tends to feed more during the day than either the brown or rainbow trout (Scarola 1987). Brown Trout (Salmo Trutta) Habitat Brown trout typically inhabit the lower reaches of cold water streams, characterized by deep, slow- moving pools and runs. They also thrive in larger lakes of sufficient depths to maintain cool water temperatures year-round. As with other trout species, water temperature is a major limiting factor for brown trout. Optimum temperatures range from 53 to 66° F and they can tolerate temperatures near 80° F for short periods. Dissolved oxygen requirements are near saturation levels; greater than 9 mg/l at water temperatures less than 50° F (Raleigh et al. 1986). Brown trout tolerate pH from 5.0 to 9.5 but have an optimal range between 6.8 and 7.8 (Raleigh et al. 1986). Physical habitat favored by brown trout is characterized by low-gradient stream reaches with slow, deep pools and relatively silt-free rocky substrates in riffles. Preferred pool to riffle ratios are high, favoring 50 to 70% pools and 30 to 50% riffle-run habitat. Well vegetated, stable banks and relatively constant stream flows are also important; overhead canopy cover is increasingly important as stream widths and depths decrease (Raleigh et al. 1986). 3 Age and