Survival Of Brook Trout Research Articles

Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) summer thermal habitat use in streams with sympatric populations

This study addresses the need to examine the thermally mediated interactions of fish with their natural environment by investigating the shift in thermal habitat occupation for sympatric Brook and Brown Trout populations. We observed upstream Brook Trout and Brown Trout population shifts during the summer, with thermal habitats showing an increased number of Brown Trout, while some sites also displayed a decrease in the number of Brook Trout. Overall, there was an increased incidence of overlapping habitat occupation at the end of the summer. Brown Trout occupied optimal resting and feeding thermal habitat locations, which can potentially affect growth rates and Brook Trout's survival. Population shifts did not occur at elevated water temperatures as expected but seem driven by temperatures that are optimal for growth. Observed population shifts can lead to increased interactions between the two species throughout the summer. The results provide a better understanding of how future, longer-term, thermal habitat modifications may modify species interactions, which are critical for salmonid conservation efforts.

Declining Aluminum Toxicity and the Role of Exposure Duration on Brook Trout Mortality in Acidified Streams of the Adirondack Mountains, New York, USA.

Mortality of brook trout Salvelinus fontinalis and water chemistry were characterized in 6 headwater streams in the western Adirondacks of New York during spring 2015, 2016, and 2017 and compared with results from analogous tests done between 1980 and 2003 in many of the same streams, to assess temporal changes in toxicity and inorganic monomeric aluminum (Ali) concentrations, and the role of Ali exposure duration on brook trout survival. The Ali concentrations of 2 and 4 µmol L–1 corresponded to low‐to‐moderate and high mortality thresholds, but prolonged exposure to ≥1 µmol Ali L–1 also produced mortality. The variability, mean, and highest Ali concentrations in Buck Creek year round, and in several other streams during spring, have decreased significantly over the past 3 decades. Logistic models indicate that Ali surpassed highly toxic concentrations in Buck Creek for 3 to 4 mo annually during 2001 to 2003 and for 2 to 3 wk annually during 2015 to 2017. The loss of extremely high Ali episodes indicates that toxicity has declined markedly between the 1989 to 1990, 2001 to 2003, and 2015 to 2017 test periods, yet Ali concentrations can still cause moderate‐to‐high and complete (100%) mortality. The logistic models illustrate how mortality of brook trout in several Adirondack streams likely decreased in response to the 1990 Amendments to the United States' Clean Air Act (which decreased acidity, Ali concentrations, and duration of toxic episodes) and offer a means to predict how changes in US regulations that limit emissions of NOx and SOx (and N and S deposition loads) could affect fish survival and stream ecosystems in this region and across the Northeast. Environ Toxicol Chem 2020;39:623–636. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Brook trout (Salvelinus fontinalis) movement and survival after removal of two dams on the West Branch of the Wolf River, Wisconsin

AbstractDam removals allow fish to access habitats that may provide ecological benefits and risks, but the extent of fish movements through former dam sites has not been thoroughly evaluated for many species. We installed stationary PIT antennas in 2016 and 2017 to evaluate movements and survival of brook trout Salvelinus fontinalis in the West Branch of the Wolf River (WBWR) in central Wisconsin following removal of two dams and channel modifications designed to promote fish movement. These changes provided access to lacustrine habitats that might provide suitable winter habitat or act as ecological sinks. We used multistate models to estimate transition probabilities between river sections, to determine whether brook trout: (a) moved between multiple river sections and (b) entered lacustrine habitats as seasonal refuges, but eventually returned to lotic habitat. We also used a Cormack‐Jolly‐Seber model to evaluate whether apparent survival of brook trout in the WBWR was comparable to other populations. Few fish moved among river sections or used lacustrine habitat (<5% of tagged fish); most brook trout remained in sections where they were initially tagged, potentially due to quality habitat located throughout the river. Like other studies, brook trout in the WBWR appear to experience high mortality based on low number of detections, few physical recaptures and an estimated eight‐month apparent survival rate of 0.27. In scenarios where fish can already access suitable habitat, removal of dams may not result in substantial increases in fish movement and colonisation of newly accessible habitat may not occur immediately.

Fall and Winter Survival of Brook Trout and Brown Trout in a North‐Central Pennsylvania Watershed

AbstractStream‐dwelling salmonids that spawn in the fall generally experience their lowest survival during the fall and winter due to behavioral changes associated with spawning and energetic deficiencies during this time of year. We used data from Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta implanted with radio transmitters in tributaries of the Hunts Run watershed of north‐central Pennsylvania to estimate survival from the fall into the winter seasons (September 2012–February 2013). We examined the effects that individual‐level covariates (trout species, size, and movement rates) and stream‐level covariates (individual stream and cumulative drainage area of a stream) have on survival. Brook Trout experienced significantly lower survival than Brown Trout, especially in the early fall during their peak spawning period. Besides a significant species effect, none of the other covariates examined influenced survival for either species. A difference in life history between these species, with Brook Trout having a shorter life expectancy than Brown Trout, is likely the primary reason for the lower survival of Brook Trout. However, Brook Trout also spawn earlier in the fall than Brown Trout and low flows during Brook Trout spawning may have resulted in a greater risk of predation for Brook Trout compared with Brown Trout, thereby also contributing to the observed differences in survival between these species. Our estimates of survival can aid parameterization of future population models for Brook Trout and Brown Trout through the spawning season and into winter.Received September 9, 2016; accepted March 6, 2017 Published online May 26, 2017

Long-term population demographics of native brook trout following manipulative reduction of an invader

Although laboratory studies have provided evidence for negative interactions between brook trout and brown trout, it is unknown how these interactions affect larger scale demographics in a natural setting. We tested the effects of invasive brown trout on brook trout demographics by removing brown trout from a sympatric population using a before–after control-impact study design. The study was conducted across a large stream network for a period of 6 years. Abundance of brook trout increased after brown trout removal primarily as a result of increased recruitment and immigration. Size structure also shifted towards larger individuals as a result of increased growth rates and a decrease in emigration of larger trout. Size at maturity and body condition did not change after brown trout removal. Adult brook trout survival increased during the post-treatment period in both the treatment and control reach. A decrease in flood intensity during the post-treatment time period may have led to increased survival. Adult survival may not be the best metric to use when assessing interactions between trout species, especially when the subordinate species has suitable areas to emigrate.

Effects of reduced summer flows on the brook trout population and temperatures of a groundwater‐influenced stream

AbstractWithdrawal of water from streams and groundwater is increasing in Midwestern North America and is a potential threat to coldwater fishes. We examined the effects of summer water withdrawals on brook trout Salvelinus fontinalis populations and water warming rates by diverting 50–90% of summer baseflow from a 602‐m treatment zone (TZ) in a groundwater‐influenced Michigan stream during 1991–1998. We compared density of brook trout in fall, and spring‐to‐fall growth and survival of brook trout, between the TZ and an adjacent reference zone (RZ) whose flows were not altered. Flow reductions had no significant effects on the density of brook trout in fall or spring‐to‐fall survival of brook trout. However, spring‐to‐fall growth of brook trout in the TZ declined significantly when 75% flow reductions occurred. Cold upstream temperatures and the relatively short study reach kept thermal habitat conditions excellent for brook trout in the TZ throughout the dewatering experiments. These findings suggest that brook trout can tolerate some seasonal loss of physical habitat if temperature conditions remain suitable. In summer 1999, we experimentally assessed the influence of flow reduction on the warming rate through the TZ by diverting from 0% to 90% of flow around the TZ in 3‐ or 4‐day trials on a randomised schedule. Average daily temperature increased exponentially as stream flows declined from normal summer levels. Our findings suggest the risk of trout habitat loss from dewatering is potentially large and proportional to the magnitude of withdrawal, especially as thermal conditions approach critical levels for trout.

Seasonal movement, growth and survival of brook trout in sympatry with brown trout in Midwestern US streams

AbstractSeasonal patterns in growth, survival and movement of brook trout Salvelinus fontinalis were monitored in two southeastern Minnesota streams divided into study reaches based on brown trout Salmo trutta abundance. We estimated survival and movement while testing for effects of stream reach and time using a multistrata Cormack–Jolly–Seber model in Program MARK. Multistrata models were analysed for three age groups (age‐0, age‐1 and age‐2+) to estimate apparent survival, capture probability and movement. Survival varied by time period, but not brown trout abundance and was lower during flood events. Age‐0 brook trout emigrated from reaches with low brown trout abundance, whereas adult brook trout emigrated from downstream brown trout‐dominated reaches. Growth was highest in spring and summer and did not differ across streams or reaches for the youngest age classes. For age‐2+ brook trout, however, growth was lower in reaches where brown trout were abundant. Interspecific interactions can be age or size dependent; our results show evidence for adult interactions, but not for age‐0. Our results suggest that brook trout can be limited by both environmental and brown trout interactions that can vary by season and life stage.

Size‐dependent survival of brook trout Salvelinus fontinalis in summer: effects of water temperature and stream flow

A 5 year individual-based data set was used to estimate size-specific survival rates in a wild brook trout Salvelinus fontinalis population in a stream network encompassing a mainstem and three tributaries (1.5-6 m wetted width), western Massachusetts, U.S.A. The relationships between survival in summer and temperature and flow metrics derived from continuous monitoring data were then tested. Increased summer temperatures significantly reduced summer survival rates for S. fontinalis in almost all size classes in all four sites throughout the network. In contrast, extreme low summer flows reduced survival of large fish, but only in small tributaries, and had no significant effects on fish in smaller size classes in any location. These results provide direct evidence of a link between season-specific survival and environmental factors likely to be affected by climate change and have important consequences for the management of both habitats and populations.

Spatial and Seasonal Dynamics of Brook Trout Populations Inhabiting a Central Appalachian Watershed

AbstractWe quantified the watershed‐scale spatial population dynamics of brook trout Salvelinus fontinalis in the Second Fork, a third‐order tributary of Shavers Fork in eastern West Virginia. We used visual surveys, electrofishing, and mark–recapture techniques to quantify brook trout spawning intensity, population density, size structure, and demographic rates (apparent survival and immigration) throughout the watershed. Our analyses produced the following results. Spawning by brook trout was concentrated in streams with small basin areas (i.e., segments draining less than 3 km2), relatively high alkalinity (>10 mg CaCO3/L), and high amounts of instream cover. The spatial distribution of juvenile and small‐adult brook trout within the watershed was relatively stable and was significantly correlated with spawning intensity. However, no such relationship was observed for large adults, which exhibited highly variable distribution patterns related to seasonally important habitat features, including instream cover, stream depth and width, and riparian canopy cover. Brook trout survival and immigration rates varied seasonally, spatially, and among size‐classes. Differential survival and immigration tended to concentrate juveniles and small adults in small, alkaline streams, whereas dispersal tended to redistribute large adults at the watershed scale. Our results suggest that spatial and temporal variations in spawning, survival, and movement interact to determine the distribution, abundance, and size structure of brook trout populations at a watershed scale. These results underscore the importance of small tributaries for the persistence of brook trout in this watershed and the need to consider watershed‐scale processes when designing management plans for Appalachian brook trout populations.

Drought effect on stream morphology and brook trout (Salvelinus fontinalis) populations in forested headwater streams

We assessed the effect of a severe drought in 1999 upon stream morphology and brook trout (Salvelinus fontinalis) populations in seven headwater streams in the Greenbrier and Potomac River watersheds, West Virginia. During the drought, stream discharge was 96% lower than in years of normal precipitation. As a result, habitat availability and quality over all study streams was significantly lower. Riffle area was greatly reduced (−54%) relative to available pool area (−2%). Fine sediment levels ( 6.0 mg l −1 , respectively) for brook trout survival in all streams during the drought. Brook trout populations were significantly reduced (adult 60%, Youngof-the-year 67%), and individual fish had significantly lower body condition during the drought relative to the post-drought period. Reductions in brook trout density and population condition during, and in the-post drought period, were related to spatially-limited food resources and/or increased fine sediment levels, but not to degraded water quality. Fisheries managers should consider the effect of periodic drought on brook trout populations and consider short-term harvest restrictions to abet recovery after such stochastic events.

Predator-recognition training enhances survival of brook trout: evidence from laboratory and field-enclosure studies

In this study we tested whether brook trout (Salvelinus fontinalis) can learn to recognise predators through releaser-induced recognition learning and whether this learning enhances survival of trout during encounters with a predator. In our initial experiment, we exposed hatchery-reared predator-naïve brook trout to chemical stimuli from predatory chain pickerel (Esox niger) paired with alarm signals released by damaged trout, disturbance signals, or distilled water. In subsequent tests 24 h later, when only pickerel odour was presented, trout conditioned with damage-released alarm signals exhibited antipredator behaviour (i.e., decreased movement and altered foraging patterns), in contrast to the other treatments, thereby demonstrating learned recognition of the predator. In our second experiment we showed that trout retained the ability to recognise the predator for at least 10 days. In the next series of experiments we explicitly tested whether training trout to recognise predators confers a survival benefit. During staged encounters with chain pickerel (in both the laboratory and the field), trained fish were better able to evade the predator than nontrained fish. Ours is the first study to demonstrate that fish trained to recognise predators gain a survival benefit during staged encounters with a predator.

Predator-recognition training enhances survival of brook trout: evidence from laboratory and field-enclosure studies

Predator-recognition training enhances survival of brook trout: evidence from laboratory and field-enclosure studies

Fine sediment effects on brook trout eggs in laboratory streams

This study was designed to determine effects of different fine sediments (0.43–0.85 mm in diameter) on survival of brook trout ( Salvelinus fontinalis) eggs during early developmental stages under laboratory conditions. Intragravel permeability and dissolved oxygen declined with increasing fine sediment amounts. Survival at each developmental stage generally declined with increasing fine sediment amounts, although not significantly for all stages. Differences in survival to emergence were not significant due to a large amount of variation in survival estimates. Survival of eggs and alevins declined linearly through time for all fine sediment treatments. In general, fry weight declined as the amount of fine sediment increased but fry length changed little. Our results indicate that increased levels of fine sediment may reduce survival of brook trout through early development.

Does one result trump all others? A response to Magurran, Irving and Henderson

Magurran, Irving and Henderson (1997) have reported that a population of European minnows, Phoxinus phoxinus, did not show an obvious behavioural fright reaction when they were presented with conspecific skin extract in a wild situation. Fish from the same population show a strong response when tested in aquaria. From these data the authors conclude that the fright reaction may be contingent on such factors as assessed risk and hunger. From this reasonable hypothesis they progress to the assertion that the Schreckstoff of ostariophysan fishes should not be considered an alarm pheromone. Much of their paper is devoted to arguments supporting their hypothesis that Schreckstoff cannot operate as an alarm pheromone. I argue that it is appropriate and adaptive to respond to alarm signals in a contingent manner, and attempt to answer the various arguments regarding the validity of terming Schreckstoff an alarm pheromone.

First-winter survival of rainbow trout and brook trout in the Henrys Fork of the Snake River, Idaho

We used caged fish with a cobble – boulder substrate to test the effect of fish size on first-winter survival of rainbow trout, Oncorhynchus mykiss, to compare survival of rainbow trout and brook trout, Salvelinus fontinalis, and to test for a temperature effect in each experiment. At the warmer site, over 90% of the rainbow trout in the size experiment survived the winter, and there was no significant difference between >90 and <90 mm fish. At the colder site, survival was 60% and all mortality occurred in fish <90 mm. Survival of brook trout (60%) was significantly less than that of rainbow trout (87%) but did not differ between the warmer and colder sites. Brook trout that survived were significantly larger than those that did not. Results suggest that size-dependent mortality may be more likely to occur when environmental conditions are more severe (e.g., lower temperatures, less suitable habitat). Rainbow trout experienced less mortality than brook trout when using cobble – boulder substrate as cover during their first winter; this may be the result of different winter-habitat preferences between the two species.

Survival of brook trout (Salvelinus fontinalis) embryos and fry in streams of different acid sensitivity in Shenandoah National Park, USA

Shenandoah National Park receives more atmospheric sulfate loading than any other USA national park. pH has been gradually declining in low-ANC streams for more than 10 years. We have completed four 1-to-3 month-long field bioassays in three streams differing in acid neutralizing capacity (ANC), using a total of 18,000 hatchery brook trout eyed-eggs through fry. In three of the four bioassays, embryos/fry showed poorer survivorship in the low-ANC stream, compared to the high-ANC stream. Substantial mortalities occurred under different hydrological conditions, including steady rain plus significant rain events (fall 1992), low rainfall followed by a significant rain event (spring 1993), and steady light rain and snowmelt with no large rain events (spring 1994). In a fourth bioassay (fall 1993), poor survivorship occurred in all three streams due to drought conditions. Trout placed in the intermediate-ANC stream showed variable survivorship, in two bioassays as high as in the high-ANC stream, and in one bioassay as poor as in the low-ANC stream. Baseflow ANC in the intermediate-ANC stream is 40–100 ueq/L, and pH never falls below 6.0. However, during episodes, pH in this stream sometimes fluctuates rapidly in the range of 6.0 to 7.0, and this fluctuation itself may be a source of physiological stress.

Effect of polyploidization on survival of sea, brook, and rainbow trout hybrids during incubation and early feeding period

Effect of polyploidization on survival of brook trout (Salvelinus fontinalis), sea trout (Salmo trutta morpha trutta) and rainbow trout (Salmo gairdneri) hybrids, including reciprocal crosses, during incubation and larval stages period was tested. The polyploidization induced by the thermal shock (28°C for 10 min., 40 minutes after fertilization) markedly increased hatching and fry survival when compared to the one for diploid hybrids.

Sand Bed Load in a Brook Trout Stream

An experimental introduction of sand sediment into Hunt Creek in the northern Lower Peninsula of Michigan that increased the bed load 4-5 times resulted in a significant reduction of brook trout (Salvelinus fontinalis) numbers and habitat. The brook trout population declined to less than half its normal abundance. The growth rate of individual fish was not affected. Population adjustment to the poorer habitat was via a decrease in brook trout survival rates, particularly in the egg to fry and/or the fry to fall fingerling stages of their life cycle. Habitat for brook trout and their food organisms became much poorer, as judged by the drastic reductions of both. Stream morphometry changed considerably, the channel becoming wider and shallower. Furthermore, sand deposition aggraded the streambed and eliminated most pools. The channel became a continuous run rather than a series of pools and riffles. Water velocities increased, as did summer water temperatures. Relatively small sand bed-load concentrations of only 80 ppm had a profound effect on brook trout and their habitat.

Genetic variation in weight and survival of brook trout ( Salvelinus fontinalis)

Data were from brook trout ( Salvelinus fontinalis) where four males were mated to four females in a diallel mating scheme, replicated eight times. Heritabilities computed from the sire component were 0.08 for 144 day weight and 0.60 for 243 day weight while those from the dam component were 0.34 and 0.37, respectively. Maternal variance decreased from 6% of total variance at 144 days to −6% at 243 days. Non-additive genetic variance was high at both ages. Heritabilities were estimated for cumulative survival at eight developmental stages. Heritabilities based on the sire component were low at early stages and decreased with time. Heritabilities based on the dam component were higher but followed the same pattern. Maternal variance accounted for approximately 11% of total variance at all stages except fertilization. Non-additive genetic variance was of considerable importance for all stages except fertilization. Heritabilities for survival between 144 days and 243 days were moderate (0.16 to 0.51). Low positive genetic correlations of 144 day weight with survival were obtained. Negative correlations between 243 day weight and survival suggest that selection for increased 243 day weight would indirectly select against survival. However, a moderate correlation between egg weight and 243 day survival, and a low, but positive correlation between egg weight and 243 day weight suggests that selecting heavier eggs would improve both weight and survival.

Survival of Brook Trout in a Bog‐Derived Acidity Gradient

The acidity in Bear Meadows Bog water (pH 3.7 — 4.7) is not due to carbonic acid or to any other volatile acid. The approximate pK of the unknown bog water acid(s) is 6.0 — 6.5. Fish do not occur in Bear Meadows Bog or in Sinking Creek over a 4.8—km section below the bog where water pH is too low for their survival. The lowest pH in which brook trout and white suckers were caught in Sinking Creek was 4.25 at area 5 (5.25 km below the bog) after a period of unusually heavy rainfall. At a different time brook trout alone were caught at area 4, 5.2 km below the bog, when the pH was 4.75. The lowest recorded pH at this site was 4.0. Survival times of hatchery brook trout placed in boxes in Sinking Creek was directly related to pH. Individual differences in tolerance to low pH were quite marked.