Eastern Brook Trout Joint Venture: Helping Brook Trout for over 20 years as a National Fish Habitat Partnership

Among the three species of Pacific salmon Oncorhynchus established in the Laurentian Great Lakes, juveniles of coho salmon O. kisutch are most likely to compete with brook trout Salvelinus fontinalis and brown trout Salmo trutta for food and space, because their juvenile life histories and ecologies are similar where they rear together in tributary streams. Coho salmon emerged 2–3 weeks earlier and were 6–8 mm longer than brook or brown trout at emergence during 1979 in Lake Michigan tributaries where the species were sympatric. During the first summer of life, coho salmon generally were 6–21 mm (7–54%) longer and weighed 0.3–4.1 g more than brook and brown trout. Size at emergence and first-year growth were similar among brook trout and brown trout. In laboratory stream experiments with pairs of the three species, coho salmon dominated brook or brown trout of equal size, and brook trout dominated equal-size brown trout. Competitive superiority of dominant species was based on the ability of fish to defend energetically profitable stream positions during sympatry. When released from competition, subordinate species shifted to use more profitable positions. Specific growth rates of coho salmon in the laboratory equalled rates measured in Lake Michigan tributaries. However, brook and brown trout grew more slowly in the laboratory than in the field, probably because intraspecific competition was high due to lack of cover affording visual isolation. Results suggest that the larger size and competitive superiority of coho salmon should give them an advantage over juvenile brook and brown trout in Great Lakes tributaries when resources become limiting.

Redd-substrate composition, water velocity, depth, and other environmental variables associated with redd-site selection and spawning by brook trout Salvelinus fontinalis and brown trout Salmo trutta in southwestern Ontario streams were examined. Sympatric and allopatric populations spawned in similar ranges of specific conductance (225–810 μmhos/cm), pH (7.0–8.2), dissolved oxygen (>83% saturation), and stream gradient (0.2–2.3%). Brook trout spawned exclusively in areas of groundwater seepage, typically near headwaters where streamflow did not exceed 177 litres/second. Brown trout spawned in a wider range of flows (21–600 liters/second), and utilized locations with and without groundwater seepage. Spawning by brook trout usually began by the second week of October, by brown trout a week later. Brook trout spawning periods lasted 3–5 weeks, those of brown trout, 2–4 weeks. In sympatric populations, an overlap in spawning time occurred for up to 3 weeks. Reuse of redds was mostly intraspecific, although interspecific reuse of brook trout redds by smaller brown trout did occur, particularly below barriers to upstream movement. Mean water depth over redds selected by brook (24.0 cm) and brown trout (25.5 cm) were similar (P > 0.05). However, mean stream velocities were significantly (P < 0.001) slower at brook trout (17.6 cm/second) than at brown trout redds (46.7 cm/second). Average geometric mean sediment size of brook trout redds was significantly smaller than that of brown trout redds (5.7 mm versus 6.9 mm; P < 0.02), but less well sorted. Redd-site preference by brook trout for areas of groundwater seepage and by brown trout for faster water velocities and coarser substrates minimized species interactions during spawning. Larger body size of mature brown trout (18.0–54.5 cm fork length) than of mature brook trout (8.4–29.0 cm) was probably a factor in the brown troutˈs ability to utilize faster currents where coarser gravels were found. Received December 3, 1982 Accepted August 5, 1983

Due to species introductions, brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss) occur together in many North American streams. Some have suggested that the two species do not compete because they select different habitats or are adapted to different environmental conditions. We assessed whether native brook trout and introduced rainbow trout selected different microhabitats in a small Pennsylvania stream. Underwater observations of brook and rainbow trout showed adult fish (≥ 90 mm total length) of both species were found significantly more often in deep water microhabitats than would be expected based on habitat availability. Total depth was the most important microhabitat variable in discriminating between the two species, irrespective of fish size. Adult rainbow trout were found in significantly deeper water than adult brook trout. Adult brook trout also were found significantly farther from cover and closer to the stream bottom than adult rainbow trout. Age-0 brook trout were found in significantly deeper water than age-0 rainbow trout. In small streams during low flow, water depth and distance to nearest cover are likely to be major factors in discriminating between brook and rainbow trout.

Native eastern brook trout Salvelinus fontinalis and naturalized brown trout Salmo trutta occur sympatrically in many streams across the brook trout’s native range in the eastern United States. Understanding within- among-species variability in movement, including correlates of movement, has implications for management and conservation. We radio tracked 55 brook trout and 45 brown trout in five streams in a north-central Pennsylvania, USA watershed to quantify the movement of brook trout and brown trout during the fall and early winter to (1) evaluate the late-summer, early winter movement patterns of brook trout and brown trout, (2) determine correlates of movement and if movement patterns varied between brook trout and brown trout, and (3) evaluate genetic diversity of brook trout within and among study streams, and relate findings to telemetry-based observations of movement. Average total movement was greater for brown trout (mean ± SD = 2,924 ± 4,187 m) than for brook trout (mean ± SD = 1,769 ± 2,194 m). Although there was a large amount of among-fish variability in the movement of both species, the majority of movement coincided with the onset of the spawning season, and a threshold effect was detected between stream flow and movement: where movement increased abruptly for both species during positive flow events. Microsatellite analysis of brook trout revealed consistent findings to those found using radio-tracking, indicating a moderate to high degree of gene flow among brook trout populations. Seasonal movement patterns and the potential for relatively large movements of brook and brown trout highlight the importance of considering stream connectivity when restoring and protecting fish populations and their habitats.

We studied survival, growth, exploitation, and production from five consecutive matched plantings of brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) (8.5-9.5 inches long) in East Fish Lake, Montmorency County, Michigan, 1958-1962. Stocked fish were given varying fin clips for later recognition. Population numbers at several intervals between introductions were determined by Petersen-type estimates. Angler exploitation was tabulated from a complete creel census. Rainbow trout survival was about 98 percent from stocking in October to the following fishing season in April, whereas brook trout survival averaged only 49 percent. About one-third of brook trout deaths occurred between 15 October and the date of ice formation (approx. 15 December). Brook trout stayed in shallow water along shore more than did rainbow trout. Anglers caught 86 percent of the stocked rainbow trout, but only 39 percent of the brook trout. For each pound of trout stocked, anglers caught 3.59 lb of rainbow trout, but only 0.76 lb of brook trout. In addition to the better return on a poundage basis, rainbow trout provided a fishery throughout the angling season, whereas nearly all brook trout were caught during the first 10 days. The brook trout grew well (average increment 0.9 lb/yr), but the rainbow trout averaged 1.3 lb increment per year. Possibly a greater poundage return on rainbow trout would accrue if the beginning of the angling season could be delayed to take advantage of the early summer growing season. Fish managers generally maintain trout in lakes by stocking hatchery fish, because trout do not reproduce in most lakes. A distinct advantage in periodic stocking is that the manager has control over fish density. We can manage trout lake-fisheries most efficiently with an understanding of mortality, growth, and production. This report deals with results from comparable plantings of brook and rainbow trout over a 5year period (1958-62) in East Fish Lake, Montmorency County, Michigan. There have been many studies of trout growth, but few studies of population numbers (and weights) throughout the life of a brood year or a given stocking. Natural mortality is difficult to measure, because the investigator usually has information only on angler exploitation, but lacks corresponding total mortality data. Seasonal differences in natural mortality of trout were observed in a general way by 1 Contribution from Dingell-Johnson Projects F-21-R, F-27-R, and F-30-R, Michigan. 682 Alexander and Shetter (1961), Latta (1963), and Eipper (1964), but we need to understand the seasonal pattern more precisely. Our objectives in this study were to determine, from October releases of rainbow and brook trout, matched for size and numbers: (1) the relative survival and growth of the species; (2) the fraction of each species later creeled; (3) the temporal distribution of the catch; and (4) the biomass of fish flesh produced by the two species. We wish to acknowledge the assistance of past and present members of the Hunt Creek Trout Research Station staff in the collection and tabulation of data. The fine cooperation of the trout fishermen in reporting their angling results is appreciated. G. P. Cooper, M. H. Patriarche, and W. E. Schaaf reviewed the manuscript and offered many helpful suggestions.

The trout population in Valley Creek, Minnesota, changed over 15 years from virtually 100% brook trout Salvelinus fontinalis in 1965 to predominantly brown trout Salmo trutta, with some brook trout and rainbow trout Salmo gairdneri remaining. Trout densities were 6,618. hectare−1 in spring 1965 (all brook trout), and 3,430 . hectare−1 in spring 1980 (70% brown, 15% brook, and 15% rainbow trout). Initial standing stock in spring 1965 was 184 kg˙hectare−1(wet weight) of brook trout; in spring 1980, brown trout standing stock was 123 kg˙hectare−1(75%), brook trout 22 kg˙hectare−1˙(13%), and rainbow 19 kg˙hectare−1(12%), for a total of 164 kg˙hectare−1. Annual production in 1965 was 61 kg˙hectare−1 by brook trout (low owing to floods in 1965); annual production in 1979 (spring 1979 to spring 1980) was 132 kg˙hectare−1(70%) by brown, 25 kg˙hectare−1(13%) by brook, and 33 kg˙hectare−1(17%) by rainbow trout, for a total of 190 kg˙hectare−1. Mean annual precipitation, greater fluctuation in annual precipitation, notable single-day rainfall events, and occurrences of floods, erosion, and siltation all increased in 1965–1979 relative to the previous 10 years. These changes apparently were the cause of observed weak year classes of trout, decreases in invertebrate food production, and loss of cover for small trout. It is postulated that innate factors in the behavior of brook and brown trout, in interaction with the habitat perturbations, may have resulted in the replacement of brook by brown trout.

Simple models of temperature-mediated interference competition have generally failed to explain salmonid species replacement patterns along altitudinal gradients, a fact that emphasizes the need to link individual features and their relation to habitat characteristics to population-level dynamics. We compared life history parameters in stream-resident populations of brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) in eight boreal streams. By use of electrofishing data from 1000 sites, we analyzed and related differences in life history traits to habitat- and interaction-related patterns of growth and densities of brook and brown trout, respectively. Brown trout were competitively dominant throughout the size span of sampled sympatric sites and lowered growth rates in sympatry were mainly caused by environmental factors, revealing a link between brook trout invasions and habitat-related limitations on brown trout performance. Still, the frequency of allopatric brook trout sites increased in the smallest watersheds, indicating that localities with a high degree of brook trout dominance rarely sustain brown trout over time. Brook trout populations had higher turnover rates and proportions of mature females than brown trout populations. Our results suggest growth potential and its effect on population fecundity as a critical factor limiting competitive ability and distribution of brown trout in Swedish brook trout dominated headwaters.

Predicting the distribution of native stream fishes is fundamental to the management and conservation of many species. Modeling species distributions often consists of quantifying relationships between species occurrence and abundance data at known locations with environmental data at those locations. However, it is well documented that native stream fish distributions can be altered as a result of asymmetric interactions between dominant exotic and subordinate native species. For example, the naturalized exotic Brown Trout Salmo trutta has been identified as a threat to native Brook Trout Salvelinus fontinalis in the eastern United States. To evaluate large‐scale patterns of co‐occurrence and to quantify the potential effects of Brown Trout presence on Brook Trout occupancy, we used data from 624 stream sites to fit two‐species occupancy models. These models assumed that asymmetric interactions occurred between the two species. In addition, we examined natural and anthropogenic landscape characteristics we hypothesized would be important predictors of occurrence of both species. Estimated occupancy for Brook Trout, from a co‐occurrence model with no landscape covariates, at sites with Brown Trout present was substantially lower than sites where Brown Trout were absent. We also observed opposing patterns for Brook and Brown Trout occurrence in relation to percentage forest, impervious surface, and agriculture within the network catchment. Our results are consistent with other studies and suggest that alterations to the landscape, and specifically the transition from a forested catchment to one that contains impervious surface or agriculture, reduces the occurrence probability of wild Brook Trout. Our results, however, also suggest that the presence of Brown Trout results in lower occurrence probability of Brook Trout over a range of anthropogenic landscape characteristics, compared with streams where Brown Trout were absent.

Although considerable information exists on habitat use by stream salmonids, only a small portion has quantitatively examined diurnal and nocturnal habitat variation. We examined diel variation in habitat use by age-0 and age-1+ brook trout (Salvelinus fontinalis) during summer and autumn in a headwater stream in northern Pennsylvania. Habitat variables measured included cover, depth, substrate, and velocity. The most pronounced diel variation occurred in the use of cover during both seasons. Both age-0 brook trout and age-1+ trout were associated with less cover at night. Age-0 brook trout occupied swifter water during the day than at night during both seasons, but the difference was not significant. Increased cover, depth, and substrate size governed the habitat of age-1+ brook trout. Our findings support the need for a better understanding of diel differences in habitat use of stream salmonids when considering habitat enhancement and protection.

We developed a multi‐scale conservation planning framework for brook trout (Salvelinus fontinalis) within the Chesapeake Bay watershed that incorporates both land use and climate stressors. Our specific objectives were to (1) construct a continuous spatial model of brook trout distribution and habitat quality at the stream reach scale; (2) characterize brook trout vulnerability to climate change under a range of future climate scenarios; and (3) identify multi‐scale restoration and protection priorities for brook trout across the Chesapeake Bay watershed. Boosted regression tree analysis predicted brook trout occurrence at the stream reach scale with a high degree of accuracy (CV AUC = 0.92) as a function of both natural (e.g., water temperature and precipitation) and anthropogenic (e.g., agriculture and urban development) landscape and climatic attributes. Current land use activities result in a predicted loss of occurrence in over 11,000 stream segments (40% of suitable habitat) and account for over 15,000 km (45% of current value) of lost functional brook trout fishery value (i.e., length‐weighted occurrence probability) in the Chesapeake Bay watershed. Climate change (increased ambient temperatures and altered precipitation) is projected to result in a loss of occurrence in at least 3000 additional segments (19% of current value) and at least 3000 km of functional fishery value (9% of current value) by 2062. Model outcomes were used to identify low‐ and high‐quality stream segments within relatively intact and degraded sub‐watersheds as restoration and protection priorities, respectively, and conservation priorities were targeted in watersheds with high projected resilience to climate change. Our results suggest that traditional restoration activities, such as habitat enhancement, riparian management, and barrier removal, may be able to recover a substantial amount of brook trout habitat lost to historic landscape change. However, restoration efforts must be designed within the context of expected impacts from climate change or those efforts may not produce long‐term benefits to brook trout in this region.

Brook Trout Salvelinus fontinalis have been introduced across the western USA, where the species competes with and often replaces native salmonids. Nonnative Brook Trout are difficult to eradicate; thus, new removal strategies are needed. One novel methodology couples the partial suppression of wild Brook Trout with the replacement of MYY Brook Trout (males with two Y chromosomes). If MYY fish survive to reproduce with wild female Brook Trout, their progeny will be 100% male, which eventually shifts the sex ratio and theoretically extirpates the population. However, the effectiveness of this approach depends on survival and reproduction of MYY fish relative to the surviving wild conspecifics. From 2018 to 2020, we annually removed an estimated 45.7% of wild Brook Trout from three streams in New Mexico and stocked fingerling MYY Brook Trout (mean TL = 94 mm; range = 61–123 mm) targeting 50.0% of wild annual abundance estimates. Annual survival for MYY and wild Brook Trout was similar in Leandro Creek (MYY = 0.63 and wild = 0.63) and Rito de los Piños (MYY = 0.37 and wild = 0.46) but differed in Placer Creek (MYY = 0.28 and wild = 0.75). During spawning, we evaluated the reproductive potential of MYY Brook Trout by comparing the percentage of sexually mature male Brook Trout comprised of MYY fish to the percentage of hybrid (MYY × wild) F1 progeny. By the second spawning season (2019), MYY fish comprised 59.8, 50.4, and 34.5% of milt-producing Brook Trout, which resulted in 55.1, 33.3, and 0% hybrid progeny in Leandro Creek, Rito de los Piños, and Placer Creek, respectively. We demonstrated that MYY fish exhibit similar vital rates compared with wild conspecifics in two of three streams; however, differences among streams highlights unforeseen variables that influence MYY survival and reproduction. The study offers promising results of the MYY approach for potentially eradicating unwanted Brook Trout populations.

In the western United States, exotic brook trout Salvelinus fontinalis frequently have a deleterious effect on native salmonids, and biologists often attempt to remove brook trout from streams by means of electrofishing. Although the success of such projects typically is low, few studies have assessed the underlying mechanisms of failure, especially in terms of compensatory responses. A multiagency watershed advisory group (WAG) conducted a 3-year removal project to reduce brook trout and enhance native salmonids in 7.8 km of a southwestern Idaho stream. We evaluated the costs and success of their project in suppressing brook trout and looked for brook trout compensatory responses, such as decreased natural mortality, increased growth, increased fecundity at length, and earlier maturation. The total number of brook trout removed was 1,401 in 1998, 1,241 in 1999, and 890 in 2000; removal constituted an estimated 88% of the total number of brook trout in the stream in 1999 and 79% in 2000. Although abundance of age-1 and older brook trout declined slightly during and after the removals, abundance of age-0 brook trout increased 789% in the entire stream 2 years after the removals ceased. Total annual survival rate for age-2 and older brook trout did not decrease during the removals, and the removals failed to produce an increase in the abundance of native redband trout Oncorhynchus mykiss gairdneri. Lack of a meaningful decline and unchanged total mortality for older brook trout during the removals suggest that a compensatory response occurred in the brook trout population via reduced natural mortality, which offset the removal of large numbers of brook trout. Although we applaud WAG personnel for their goal of enhancing native salmonids by suppressing brook trout via electrofishing removal, we conclude that their efforts were unsuccessful and suggest that similar future projects elsewhere over such large stream lengths would be costly, quixotic enterprises.

The decreased range of native brook trout Salvelinus fontinalis in the Great Smoky Mountains National Park has been attributed to competition with introduced rainbow trout Oncorhynchus mykiss. To determine whether brook trout were displaced from preferred sites in the presence of rainbow trout, we made underwater observations of microhabitat use to characterize positions of individual fishes in a section of Palmer Creek, North Carolina, where both species occur. We then reduced rainbow trout numbers by about 80% by electrofishing and repeated our underwater observations on the remaining brook trout to determine whether the species underwent changes in microhabitat use. We found differences in characteristics of focal points selected by the two species. Focal points of age-0 brook trout were similar to those of rainbow trout for distance to overhead cover. After rainbow trout were reduced, age-0 brook trout shifted to positions significantly farther from overhead cover. Brook trout age 1 or older ...

A small, second-order stream in the southern Appalachians was sampled every 2 months from September 1978 to October 1979. The 1.5-km study segment was divided into 50, 30-m sections grouped into three areas: A downstream area with only rainbow trout Salmo gairdneri; a middle, mixed-trout area; an upstream area with predominantly brook trout Salvelinus fontinalis. Although a few fish of both species exhibited substantial movements, the majority of fish moved less than 30 m either upstream or downstream. Growth rates of both species were approximately equal until the spring of their second year, when rainbow trout outgrew brook trout and thereafter maintained a size-at-age advantage. Rainbow trout, particularly the 1978 cohort, dominated trout production in the stream. Even in the brook trout area, where the density of 1978 cohort brook trout was twice that of 1978 cohort rainbow trout, rainbow trout outproduced brook trout by 1.20 g/m2 to 1.14 g/m2. Declining mean biomass of older fish of both spe...

Poststocking growth, movement, and catch were compared among hatchery brook trout Salvelinus fontinalis, rainbow trout Oncorhynchus mykiss, and brown trout Salmo trutta in a fifth-order river. Associations of species, size, and stocking date with angler catch were also examined. The river is episodically acidified, and during summer it approaches lethal maximum temperatures for trout. Catchable-sized brook and rainbow trout (168–458 mm total length) were stocked in the late spring of 1996 and 1997. Brown trout were stocked only in 1997. Fish were marked with visible implant tags and were recovered through October of each year. All three species had negative daily growth rates in weight over the summer and early fall. Rainbow trout stocked in 1997 tended to move downstream after stocking, whereas the other groups showed no strong movement trend. Recovery rates significantly differed between brook and brown trouts stocked in early June and those fish stocked in late May. Large (&amp;gt;300-mm) rainbow trout were caught at higher rates than small (&amp;lt;260-mm) fish were. Anglers were estimated to have caught 72% of the stocked brook trout, 51% of the rainbow trout, and 18% of the brown trout. High summer water temperatures (&amp;gt;20°C) did not affect angler catch rates because cool refuges within the river concentrated and made the stocked fish—especially brook trout—vulnerable to angling. By stocking more than one species, we were able to create diversified angling opportunities and sustain a fishery in this thermally marginal river over the entire summer season.