Trout Fishery Research Articles

Catch-and-Release Management of a Trout Stream Contaminated with PCBs

Abstract Due to health risks associated with PCB contamination, the Connecticut Department of Environmental Protection chose to apply catch-and-release regulations to the Housatonic River, which had previously supported one of the most popular put-and-take trout fisheries in Connecticut. The management change was successful in maintaining a highly rated recreational fishery. Stocked brown trout Salmo trutta survived up to five summers and grew to maximum total lengths of about 400 mm. Through 5 years, fish stocked as adults (254–305 mm) and yearlings (152–229 mm) had average annual survivals of 39 and 42%, respectively. Survival of fingerlings (< 152 mm) averaged 22%. With holdover trout present after the first year of catch-and-release management, 50-66% of the fish caught by anglers exceeded the maximum length of 305 mm of trout stocked for put-and-take purposes in other Connecticut streams. Also, an average of 38% more trout by number and 210% more trout by weight were caught and released than were sto...

Biological detoxification of precious metal processing wastewaters

Abstract A biological treatment plant is utilized at the Homestake Mine in Lead, SD, to effect detoxification of a daily discharge of 4 million gallons of wastewater. The wastewater matrix requiring treatment contains cyanide, ammonia, toxic heavy metals, and a variable component of toxic chemicals associated with extractive metallurgy and mining operations. Rotating biological contactors (RBCs) are used to attach the biofilm. Cyanides and heavy metals concentrations are reduced by 95–98%. The treated discharge makes up as much as 60% of the total flow in a cold‐water trout fishery. This receiving stream, which remained lifeless for over 100 years as a mine drainage, has now become an established trout fishery and recently yielded a state record trout.

Pumping Alkaline Groundwater to Restore a Put-and-Take Trout Fishery in a Stream Acidified by Atmospheric Deposition

The purpose of this study was to pump alkaline groundwater into Linn Run in southwestern Pennsylvania to neutralize acidity, reduce dissolved aluminum concentrations, and protect stocked brown trout Salmo trutta and brook trout Salvelinus fontinalis during the springs of 1985 and 1986. A regression model was used to estimate the groundwater volume needed to maintain predetermined stream pH levels for a given streamflow. Equal numbers of brook and brown trout were stocked in a treatment stream section influenced by the wells and a naturally alkaline downstream reference section before and during the fishing season each year. Groundwater addition increased mean stream pH from 4.9 upstream of the wells to 6.0 in the treatment section and reduced mean dissolved aluminum from 0.36 mg/L to 0.03 mg/L above and below the wells, respectively. A large runoffepisode following the 1985 preseason stocking overwhelmed the capacity of the wells to neutralize Linn Run, causing at least 25% mortality and reducing the catch rate of brown trout in the treatment section. No mortality of caged trout occurred in the treatment section except during this large runoff event. However, mortality was rapid for caged trout upstream of the wells; median survival times were 67 and 29 h for brook and brown trout, respectively. Otherwise, angler catch rates and trout harvest were not significantly different between the treated and reference sections. Electrofishing surveys revealed greater downstream than upstream movement of stocked trout, which may indicate a response to water chemistry. Alkaline groundwater additions also caused an increase in the density of native brook trout in the treatment section via upstream migration from downstream refuges influenced by groundwater.

Conservation and management of brown trout, Salmo trutta, in Scotland: an historical review and the future

SUMMARY. 1. Intensive research into the life history of brown trout started In 1948 when the Brown Trout Laboratory was opened in Pitlochry. Over the next 15 years significant contributions were made to the brown trout literature upon which the Laboratory based advice to landowners and anglers wanting to develop their fisheries.2. Increasing pressure from the government for more work on Atlantic salmon tended to divert research funds and time away from brown trout investigations. The International Biological Programme's major study at Loch Leven from 1966 to 1972 ensured a continuing interest in trout in standing waters. Over this period little attention had been paid to trout in rivers. This changed when a number of investigations were started on the River Tweed by Edinburgh University.3. A major constraint to brown trout conservation and management has been illegal fishing and lack of records on stocking activities and catches. The granting of Protection Orders under the Freshwater and Salmon Fisheries (Scotland) Act, 1976, has been a major incentive to increased interest in the improvement of trout fisheries.4. Brown trout stocks have been reduced in certain areas due to the effects of afforestation, acidification, land drainage and farm wastes. Various remedial measures have been proposed and implemented.5. To meet the increasing demands for trout fishing, many loch and reservoir fisheries are now stocked with rainbow trout in preference to brown trout. Attention should be paid to the interaction of these two species in both standing and in running waters., where fish farm escapees and inadvisable releases go unrecorded.7. Research into the genetic effects on wild stocks from the liberation of large numbers of hatchery‐reared brown trout has been lacking and probably many ‘pure’ indigenous stocks have been lost. More work in this field is essential.8. Proposals are outlined for future brown trout research and recommendations are made for better management. Suggestions are also put forward for changes in the legislation to further protect Scottish brown trout stocks.

Effects of hydroelectric scheme on fluvial ecosystems within the Spanish Pyrenees

AbstractThe effects on faunal communities of a high head, low capacity hydroelectric power project are evaluated for the River Cinca, a Pyrenean tributary of the River Ebro (North East of Spain). The macrobenthic fauna of the regulated Cinca river is compared with the unregulated River Ara. Colder summer water temperatures in the River Cinca are shown to have caused a reduction in species richness of the macrobenthic community as a consequence of the elimination of thermophilous species. Reduced temperatures may also explain the lower growth rate and productivity of the trout populations. Sudden flow fluctuations caused by hydropower generation influence the downstream macrobenthic communities; their populations are less abundant (reduction in densities and biomass) and their structure is less diverse. Although trout fisheries do not seem to be directly affected by sudden flow fluctuations, the limitation of their food resources (benthos), has reduced trout production and turnover ratio.

Predicted acid mine drainage impacts to the Buckhannon River, WV, U.S.A.

This study was conducted to determine acid, Al, Cd, Cu, Fe, Mn, and Zn loads originating from coal mines in the Buckhannon River watershed in central West Virginia, U.S.A, and to predict the impacts of those loads should they enter the river as unneutralized acid mine drainage. Net alkaline loads at the river mouth would decrease from 3341 to 1014 and 7488 to 1463 kg day−1 CaCO3 during the summer and spring sampling periods, respectively, causing pH decrease below the level required for surviveal of warm water fish species in the affected study area and for a viable trout fishery in a 12 km segment of the river. Aluminum could have major impacts through much of the study area. Zinc could impact the existing cold water fishery and may cause deleterious effects to the warm water fishery. It was not possible to draw accurate conclusions about impacts of Fe because of the uncertainties of toxicity data and rates of oxidation. It appears that Cd and Cu would probably not impact the river. Manganese may cause a water treatment problem for the city of Buckhannon.

Loch fleet — a research watershed liming project

A research watershed liming project is being carried out at Loch Fleet in the Galloway District of southwest Scotland. This acid loch originally supported a brown trout fishery, but the number of fish caught by anglers declined during the 1950's and the fishery eventually disappeared about 20 yr ago. After 2 yr of pretreatment data collection, the first set of land time applications took place in the spring of 1986, and the resulting surface water chemical changes are very encouraging. Increases in pH and Ca concentration and decreases in A1 (especially the toxic labile monomeric fraction) concentrations have been observed in the streams and waters draining the treated subcatchments in the loch itself and in the loch outlet. Also, the normal trend for pH and Ca concentration to fall during periods of high flow in the main feeder stream has been reversed. In the spring of 1987, the loch was restocked with brown trout. Initial indications are that there has been very good survival of these fish, and that they managed to spawn during the 1987/88 winter. The chemical and biological changes brought about by the land treatments are described in detail.

Catchable Trout Fisheries: The Need for Assessment

Abstract State fisheries agencies were questioned regarding their catchable-size (>178 mm) salmonid stocking programs, specifically: (1) number, species, and propagation cost of catchables stocked; (2) total length of stream and area of impoundments stocked; (3) methods used to estimate angler effort and harvest of catchables; (4) extent to which these techniques have been employed in the past 10 years. In 1983, 43 states stocked in excess of 50 million catchable-size trout at a production cost of nearly $37 million. Rainbow trout (Salmo gairdneri) was the most popular species, predominating in 28 states and accounting for more than 77% of all catchable salmonids stocked. Brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) were the next most frequently stocked salmonids (11.0% and 10.1% of total, respectively). More than 54,000 km of streams and 550,000 ha of ponds, lakes, and reservoirs were planted with catchables in 1983. Most methods utilized by management agencies to assess use and har...

Factors limiting fish populations in the Loch Fleet system, an acidic drainage system in south‐west Scotland

Loch Fleet is an oligotrophic upland lake in Galloway, south‐west Scotland. It once supported a brown trout, Salmo trutta L., sport fishery with low annual catches (&lt; 150 fish year −1) but catches declined markedly after 1950 and no fish were caught after 1975. Diatom records for the lake sediments indicate acute acidification since 1975, pH changing from c. 5–8 to 4–6.In 1984 a project was set up at Loch Fleet to investigate techniques of acidity mitigation, with a view to restoring fisheries in this and similarly affected waters. An underlying assumption of the project was that fish had been lost as a direct result of acidity and associated factors. Studies were therefore undertaken during a 2‐year baseline period (1984–1986) to validate this assumption.Fish surveys using a variety of techniques (gill‐netting, trapping, electrofishing) confirmed that trout were absent from the Loch and its afferent streams, and also from its main outlet stream, the Little Water of Fleet, for a distance of 7 km downstream. Trout were present below this point but are prevented from passing upstream by a 5‐m waterfall. Eels, Anguilla anguilla L., were present throughout the Little Water of Fleet, though not in the Loch itself. Population densities of both species were low, with less than 7 eels and 5 trout per 100 m2.Survival studies using brown trout ova and yolk‐sac fry indicated that conditions in the Loch and its afferent streams were acutely toxic to these stages as a result of the low pH (pH 4.5), low calcium (I mg l−1) and high aluminium concentrations (200 μg 1 −1 total Al, 60 μg 1 −1 inorganic monomeric Al). Trout fingerlings could survive these conditions in short‐term tests (9 days) but, in chronic exposure tests lasting up to 180 days carried out in situ in streams adjoining the loch, no fish survived this period. This toxicity was eliminated in experiments where pH was raised to 5.4 by KOH addition.It is concluded that the loss of the brown trout fishery at Loch Fleet occurred as a direct result of acidity and related factors, probably acting in the first instance on the sensitive intra‐gravel ova and yolk‐sac fry stages, leading to recruitment failure.

Policy Making within an Adaptive Management Framework, with an Application to Lake Trout (Salvelinus namaycush) Management

Using lake trout (Salvelinus namaycush) rehabilitation in the Laurentian Great Lakes as an example, we combine a policy design process known as "adaptive management" in biological circles with basic concepts found in natural resource economics. Emerging from this synthesis of biological and economic thought is a practical method for making policy choice in fisheries in the presence of biological uncertainty. We introduce this method by first reviewing key biotic uncertainties which impede the progress of lake trout rehabilitation. Drawing upon these uncertainties, a framework is proposed for developing a set of policy options. Included in these options are "actively adaptive" policies which are purposely experimental in hopes of both reviving the lake trout fishery and concurrently yielding data which may alleviate the nagging uncertainties. Using basic concepts from natural resource economics, we then outline how, in the presence of the key uncertainties, the policy which most likely maximizes socioeconomic gains can be chosen from the various options. We conclude with some brief policy implications for lake trout rehabilitation.

Relative catch ability and performance of three strains of rainbow trout, Salmo gairdneri Richardson, in a small fishery

Abstract. The performances of two strains of rainbow trout, Salmo gairdneri Richardson, and a hybrid were assessed in a put-and-take fishery against stock from the normal supplier. The three batches of experimental fish were reared to the size usually stocked in the fishery and they and two batches of the normal stock fish were given distinctive dye-marks using a Panjet inoculator. Anglers’ returns were analysed and demonstrated that there were significant differences in the catchability of the various types of fish throughout the trial period. There was no apparent difference between strains in their susceptibility to the fly-fishing methods employed, nor between their growth rates whilst in the fishery, despite the clear superiority of some genotypes under fish-farm conditions. These factors are discussed in relation to the management of put-and-take trout fisheries.

Prediction of Wild Brown Trout Catch Rates from Estimated Yearling Population Density and Fishing Intensity

Abstract Catch rates for wild brown trout (Salmo trutta) in New York streams were predicted successfully by equations of the form C/f= N1/bf+ a where C/f is catch per hour of fishing, N1 is late summer or early fall population density of yearling wild brown trout, f is fishing intensity in hours of fishing per unit of stream area, and a and b are constants. Correlations between observed and predicted catch rates were higher for total catch than for creeled catch, and for mean values of N1 than for single-year values. The equations can be used in setting stocking rates aimed at target catch rates, determining need for protective regulations, and estimating the potential value of wild trout fisheries.

BENEFITS ASSOCIATED WITH MEETING WATER QUALITY STANDARDS AT LAKE TANEYCOMO, MISSOURI

ABSTRACT Lake Taneycomo, a 700-ha hydropower impoundment in southwestern Missouri, supports an excellent put-grow-and-take trout fishery with a benefit:cost ratio of 22:1. However, seasonal dissolved oxygen fluctuations resulting from the hypolimnetic discharge from upstream Table Rock Lake have been a concern since 1970. The biological and socioeconomic effects of low levels of dissolved oxygen on the fishery were recently documented. When dissolved oxygen drops below 6 mg/L, fishing success declines. This change in fishing quality affects visitation to the area and the economic benefits generated by the fishery. The net economic benefit of the fishery to the local economy is $9.9 million, and the current estimated loss of benefits is $358,000 per year because of low dissolved oxygen. The U.S. Army Corps of Engineers has proposed a structural modification of Table Rock Dam to solve the problem.

Performance of rainbow trout, Salmo gairdneri Richardson, in a put-and-take fishery, and influence of anglers’ behaviour on catchability

Abstract. Stock, catch and fishing effort statistics for a 12·5-ha lowland pul-and-lake trout fishery have been used to compute the ‘catchability’ of rainbow trout, Salmo gairdneri Richardson, during the fishing seasons 1980–1983. Seasonal trends in the fishes’ susceptibility to capture by fly-fishing are apparent but there was no indication that, in this fishery, newly stocked fish were more vulnerable than the longer-term residents. This consistency of recapture rates of rainbow trout, relative to the population available, is a function both of the fish's behaviour and that of the anglers themselves, and it is suggested that for management purposes the latter must be taken into account. In the fishery studied rainbow trout grew well at fish densities below 60 kg ha−1, but even with overall recapture levels exceeding 80% the yield of the fishery was less than the weight of fish stocked. The selection of strains of rainbow trout which satisfy the requirements of sport fisheries is discussed.

A pike management strategy for a trout fishery

The efficiency of pike removal from a chalkstream trout fishery, by an angling society using electrofishing, was estimated over five successive autumns using mark‐recapture methods. It averaged c. 50% for pike aged 1+ years or more. Numbers of 3+ and older pike decreased from 3.7 ha‐1 (1980) to 1.4 ha‐1 (1984), but there was no corresponding reduction in recruitment success. Both pike immigration and an inverse relationship between natural and fishing mortality could have reduced the effect of the pike culls. The mean weight of 0+ pike increased from 19.4 g to 48.2 g over the 5 years, but there was no change in the growth rates of older pike. Only the larger pike were able to eat the larger trout stocked, and the reduction in numbers of 3 + and older pike appears to have reduced the predation pressure on the trout population. Angling effort increased more than three‐fold over the 5 years studied and rod‐catches more than doubled, but catch‐per‐unit‐effort was extremely variable between years. The increased rod catch occurred despite the decrease in numbers of large (&gt; 33 cm) trout stocked in the spring and early summer. Compared with pre‐cull years, the angling society saved about ş850 (present day prices) by stocking fewer trout.

Stocking and Hooking Mortality of Planted Rainbow Trout in Jocassee Reservoir, South Carolina

Abstract Attempts to establish a put-grow-and-take fishery for rainbow trout (Salmo gairdneri) in Jocassee Reservoir, South Carolina failed despite plantings of 200,000 fish in 1972-1979 because few of the stocked fish survived to legal size. At the same time, a fishery for brown trout (Salmo trutta) was established successfully by planting far fewer fish. Experiments were conducted to determine if stress at stocking and injuries and stress associated with catch and release of fish by shoreline anglers were responsible for the poor survival of rainbow trout. Only 1 of the 606 rainbow trout stocked in floating wire cages anchored in the reservoir died during the first 3 days, and fewer rainbow trout than brown trout died as a result of catch-and-release fishing during the first 11 days after stocking. Thus, these factors were not responsible for the lack of success in establishing a rainbow trout fishery in this reservior.

Rainbow Trout Returns from Fingerling Plantings in Dillon Reservoir, Colorado, 1975-1979

Fingerling rainbow trout (Salmo gairdneri) were stocked in Dillon Reservoir, Colorado, in 1974-1978 and evaluated in terms of harvest, percent return to creel, and cost per fish harvested. The average annual harvest of stocked rainbow trout was 18,300 (14/hectare). The average return to the creel was 4.8% and the average cost per trout harvested was $6.78. Two factors are suspected to be responsible for these low returns and resultant high costs - predation by resident brown trout (Salmo trutta) and competition with kokanee (Oncorhynchus nerka) for a limited zooplankton forage base. Thus, Dillon Reservoir is not considered to be a good site for a put-grow-and-take rainbow trout fishery. Based on our findings, fishery managers should be hesitant to stock fingerling rainbow trout in impoundments with substantial populations of predatory fish and/or potential competitors.

The Loch Dee Project: a Study of the Ecological Effects of Acid Precipitation and Forest Management on an Upland Catchments in Southwest Scotland. 1. Preliminary Investigations

A description is given of the preliminary stages of an ecological study of the effects of acid precipitation and coniferous afforestation in the Loch Dee Catchments in the Galloway area of south-west Scotland. Information on the current chemical, hydrologieal and biological status of the loch and its three major tributaries is presented. Acid precipitation episodes of pH < 4.5 occurred for 20% of rainfall in 1981 and were generally coincident with the movements of air masses from areas of high sulphur emissions to the south, east and north. In 1981 the mean pH of the loch was 5.2 and in recent years artificial slocking of the loch has been employed to maintain a viable trout fishery. The densities of fish populations in two of the major inflowing streams were sometimes < 10 fish per 100 m2. During high stream flow, the concentrations of free acidity (H+) and aluminium were in the range where a significant reduction in the survival of hatching trout would be expected. The impact of various forms of calcium carbonate, spread on the catchments or added directly to one inflowing stream, is being monitored to assess long-term changes in stream and loch ecology.

Biological Treatment of Cyanidation Waste Waters

An attached growth aerobic biological treatment process has been developed at Homestake Mining Co.’s Lead operation which not only oxidizes free and complexed cyanides, including the stable iron complexed cyanides, but also thiocyanate, and the oxidation byproduct ammonia. Through the employment of a mutant strain of bacteria which has been gradually and specifically acclimated to the waste, these potential pollutants are mineralized to relatively harmless sulfates, carbonates, and nitrates. The resultant effluent, through toxicological testing, has been shown compatible with the receiving stream, which serves as a cold water marginal trout fishery.

Effects of Dissolved-Oxygen Depletion on the Rainbow Trout Fishery in Lake Taneycomo, Missouri

Abstract Lake Taneycomo, a 700-hectare hydroelectric impoundment in Taney County, southwestern Missouri, is fed by cool hypolimnetic waters from an upstream reservoir. A popular put-grow-and-take fishery for rainbow trout Salmo gairdneri has become established in Lake Taneycomo, but fishing success and effort decline each fall when oxygen-depleted waters enter the lake. The fishery was examined in detail from June 1978 through May 1980. During this period, catch rates of rainbow trout averaged 0.55 fish/hour, and were influenced by dissolved-oxygen concentration, number of fish available to be caught, discharge rates from the upstream reservoir, angler experience, and water temperature. A decrease of 1 mg/liter dissolved oxygen, between 6.0 and 2.4 mg/liter, reduced catch rates by 0.1 fish/hour. During the fall, a change in catch rate of 0.1 fish/hour can result in a change of 20,000 hours of fishing at Lake Taneycomo. The expected annual economic loss to the Taney County economy due to low concentrations...