Game Fisheries Research Articles

Elucidating the effects of acute and chronic exposure to 2,4-Dichlorophenoxyacetic acid on fathead minnow (Pimephales promelas) innate immunity

Aquatic herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D) formulations, are commonly used for invasive species management throughout the United States. Ecologically relevant concentrations of 2,4-D can impair essential behaviors, reduce survival, and act as an endocrine disruptor; however, there is limited knowledge of its effects on the health of non-target organisms. Here, we investigate the acute and chronic exposure impacts of 2,4-D on adult male and female fathead minnow (Pimephales promelas) innate immune function. We exposed both adult male and female fathead minnows to three different ecologically relevant concentrations of 2,4-D (0.00, 0.40, and 4.00 mg/L) and took blood samples at three acute time points (6, 24, and 96 h) and one chronic time point (30 days). We found that male fatheads had higher total white blood cell concentrations when exposed to 2,4-D at the acute time points. For the females, only proportions of specific cell types were altered when exposed to 2,4-D at the acute time points. However, we did not observe any significant impacts of chronic exposure to 2,4-D on any innate immune responses for either males or females. Overall, this study is the first step in answering an important question for game fisheries and management agencies while providing insight to future studies that investigate the impacts of herbicide exposure to freshwater fish health and immunity.

Establishment and Characterization of Eye Muscle Cell Line from Snow Trout, Schizothorax richardsonii (Gray, 1832), a Vulnerable Coldwater Fish, for In Vitro Studies

Schizothorax richardsonii, commonly called snow trout is a vulnerable coldwater fish distributed in India and adjoining countries, is an important resource as food, ornamental and game fishery. A cell line, designated as SREM-1, has been established from the eye muscle of S. richardsonii using explant method and cultured in Leibovitz’s L-15 medium. The growth studies at 20-32°C temperatures and 5-20% of fetal bovine serum (FBS) concentrations revealed that SREM-1 cells exhibited optimal growth at 28°C in L-15 medium containing 20% FBS. Cell type was confirmed primarily as epithelial in nature by immuno-phenotyping assay and was sub-cultured for >55 times since its development. The origin of the cell line was confirmed by sequencing of cytochrome oxidase c subunit I and 16S rRNA genes. SREM-1 cell line is free from mycoplasma contamination and has been cryopreserved at different passage levels with revival efficiency of 70-80% after 6 months. The SREM-1 cell line was successfully transfected and also employed for evaluating in vitro cytotoxicity against a heavy metal, mercuric chloride. The newly established cell line of this vulnerable species would be useful as a model for aquatic toxicological and transfection studies.

Diurnal water temperature dynamics in lowland rivers: A case study from Central Poland

AbstractThe paper examines spatial and seasonal variations in diurnal water temperature dynamics in lowland rivers. Temperature data was obtained from digital temperature loggers located in nine sites across the Mazovian Lowland during the hydrological year 2016. On the basis of measurement data, mean, maximum, and minimum daily ranges were calculated in the monthly timescale, as well as the timing of extreme temperatures during the day. The results indicate that water temperature dynamics of lowland rivers have a clear seasonal pattern, with the highest variations of temperature in May and June and the lowest in January. Statistically significant differences were found in the daily temperature range between groups of the investigated sites; a higher diurnal temperature range was observed in sites draining a smaller catchment area, while larger rivers were generally more thermally stable in the daily timescale. There was also found an effect of anthropopressure on diurnal temperature dynamics in urbanized catchments, mainly due to impoundments and sewage inflows. Maximum water temperature in the studied sites usually occurred in the morning, from 06:00 to 10:00 CEST, while minimum temperature occurred in the late afternoon, from 14:00 to 18:00 CEST. Spatially, the timing of the maximum and minimum water temperatures during the day was similar in all of the investigated sites, with no statistically significant differences. However, cluster analysis indicated that in the summer half of the year the timing of the extreme temperatures was more varied between investigated sites. The results provide new insight into short-term river thermal behaviour and they are valuable in the context of game fisheries due to the significance of daily temperature variations in fish activity and feeding.

Capture-induced physiological stress and postrelease mortality for Southern bluefin tuna (Thunnus maccoyii) from a recreational fishery

Southern bluefin tuna (SBT; Thunnus maccoyii) are a popular component of the recreational large pelagic game fishery in Australia. The fishery is managed using individual fisher catch limits. Fifty-nine pop-up archival transmitting (PAT) tags were attached to individual SBT to estimate postrelease survival (PRS) rates. Fish caught on lures configured with J-hooks (n = 44) and those caught on circle hooks (n = 8) had similar PRS rates and were combined to increase sample size, revealing a PRS estimate of 83.0% (95% CI: 75.9%–90.7%, n = 54). The PRS estimate of fish caught on lures with treble hooks was much lower, 60% (95% CI: 20%–100%, n = 5). By sampling blood from 233 fish, including 56 of the PAT-tagged individuals, we show that angling duration is related to an elevation of lactate, cortisol, and osmolarity in blood plasma, indicative of increased physiological stress. Physical damage related to hooking location, angling duration, biochemical indicators of physiological stress, and handling duration were not identified as significant factors leading to postrelease mortality. The results quantify a previously unaccounted source of mortality for SBT.

Impacts of piscivorous birds on salmonid populations and game fisheries in Scotland: a review

AbstractThe Scottish populations of salmonids are important both ecologically and economically. Game fisheries for Atlantic salmon Salmo salar, sea trout Salmo trutta trutta and brown trout Salmo trutta fari are all highly acclaimed and generate substantial levels of income for Scotland, but many populations are in decline and efforts are being made to ensure the future sustainability of these species. These declines have led to a focus on the impact of piscivorous bird predation on fish populations. The purpose of our review was to assess the evidence for population‐level impacts on salmonid populations, and/or economic impacts on Scottish game fisheries of predation by the four primary UK freshwater piscivorous bird species: cormorant Phalacrocorax carbo, goosander Mergus merganser, red‐breasted merganser Mergus serrator and grey heron Ardea cinerea. There is evidence that these birds can, in some situations, remove large numbers of fish from stocked and natural fisheries. However, a lack of information on fish population levels, the numbers and species composition of feeding birds, and robust calculations of fish consumption has hampered the conversion of the results of the existing studies into useful quantitative measures of impact. As a consequence, few studies have demonstrated any reductions in numbers of breeding fish or fish productivity due to predation by piscivorous birds, or direct economic loss to fisheries in Scotland. We support a previous recommendation for a reiterative procedure of modelling, experimentation and remodelling to assess the impacts of piscivorous birds on fisheries. Wide‐scale studies of the movements of piscivorous birds, their feeding locations in relation to river characteristics, and the factors that make fish particularly vulnerable to predation are seen as important areas for future research.

Cormorant Phalacrocorax carbo occupancy and impact at stillwater game fisheries in England and Wales

This study provides an assessment of Cormorant occupancy and impact at stillwater game fisheries in England and Wales, during 1988/89 to 1992/93. A total of 167 waterbodies operated as ‘put-and-take’ trout fisheries was included within a questionnaire survey, and this provided the bulk of the data used in the analyses. The results show that Cormorants are widespread at inland stillwater game fisheries in England and Wales throughout the year, with higher densities present during October–March. Peak counts by fishery managers at 45 of the fisheries increased by about 20% per year, regardless of season. Site use by Cormorants is investigated and the results imply that large, low altitude sites that are close to rivers in southern England are more likely to be used by these birds. The survey revealed that Cormorants are widely perceived by fishery managers to be responsible for significant economic losses through consumption and/or injury of stock fish. While this may be justified locally, we found no overall relationship between Cormorant density and anglers' catches of Rainbow Trout, the principal stock fish.

Assessing the status of British wild brown trout, Salmo trutta, stocks: a pilot study utilizing data from game fisheries

SUMMARY. 1. This paper describes an analysis of results from a questionnaire (Giles, 1987) which requested information on the status of game fish stocks (especially wild brown trout Salmo trutta L.) from those Game Conservancy members who own or manage fisheries. Also included are data arising from fishery log book records which are used to indicate trends in brown trout catch per unit effort (CPUE) over past decades.2. The key finding from questionnaire returns was the widespread reporting of apparent declines of wild brown trout stocks in a total of twenty‐seven sites throughout Britain. The affected waters are geographically widespread from the south‐west of England through southern and south‐east England, south Wales, northern England and Scotland including the Western Isles. Suspected stock declines of migratory (sea) trout, salmon Salmo salar L. and grayling Thymallus thymallus L. were also reported. Where brown trout occur alone, a significantly higher proportion of questionnaire returns recorded a stock decline compared with fisheries containing both brown and rainbow trout Salmo gairdneri Richardson.3. Trout catch records from a small selection of differing fishery types are presented and the value of such data in fish stock assessment is discussed.

The interpretation of anglers’records (trout and sea trout, Salmo trutta L., and salmon, Salmo salar L.)

Abstract. This paper collates the results of five surveys which were made to determine the average catch of anglers not making a return at game fisheries. This pilot study shows that the average catch per licence/permit () may be estimated from the average and the proportion of unprompted returns, (mu) and (pu) respectively, by the empirical equation , for trout and sea trout, Salmo trutta L. Salmon, Salmo salar L., catcrl’rates may be best estimated from . Typical values for United Kingdom waters are tabulated for recent seasons. Rod catches of stillwater and migratory fish closely follow the Negative Binomial distribution. Their means and variances are shown to be related empirically by Taylor's power law: for daily records of stillwater trout and migratory fish, and for annual records of salmon, and of sea trout. A method of estimating the expected frequency distribution of catches at any water is shown. The distribution is truncated where the nil catches are not recorded and is censored where the bag is limited; here a microcomputer was programmed to compute the estimates of the mean and variance of the catches and to print the full distribution.

Accumulation of angling litter at game and coarse fisheries in South Wales, UK

Attempts were made to quantify the amounts and rates of deposition of angling litter at (a) a fly-only game fishery and (b) a coarse fishery. Considerable quantities of nylon monofilament line were recovered from the banks of the game fishery; anglers were found to drop on average 2–3 m of line per fishing trip. At the coarse fishery less nylon line was recovered; however, there were high densities of lead shot in the mud— 125 shot m −2 surface area in front of the fishing pegs. It was estimated that in excess of 15 000 lead shot (total weight about 5 kg) are deposited at the fishery, area 1 ha, each year; this represents 2–3 shot dropped per fishing trip to the site. The threat posed to wildlife arising from the presence of such angling litter is discussed.

Zooplankton Changes in a Kansas Lake 1963–1981

ABSTRACT The limnetic microcrustacean fauna of Lake Reading, located near Emporia, Kansas, now consists of 11 species of copepods and 18 species of cladocerans, with the Copepoda usually constituting at least 70 % of the adult and immature individuals observed in samples. The average annual standing crops from April 1979 to August 1981 ranged from 11.1 to 18.6 individuals per liter for the copepods compared to 5.4 to 7.7 cladocerans per liter. Leptodora kindti and Daphnia galeata mendotae have become established in the lake since 1975, and the abundance of Bosmina longirostris has declined markedly since the appearance of L. kindti. Trial stocking of the threadfin shad by Kansas Fish and Game fisheries biologists during the last two years of this study was accompanied by severe reductions in zoo-plankton abundance by late summer.

Size and Feeding of Different Types of Fishes

THE pelagic, predatory, marine fishes are a remarkable group, containing many species of great importance for both commercial and game fisheries. Some examples are the mackerel (Scomber scomber), the Thunnidae, the spearfishes (Makaira sp.) and Tarpon atlanticus.