Showing papers in "Transactions of The American Fisheries Society in 1996"
TL;DR: The Structure and Function of Running Waters (SFL) as discussed by the authors is a seminal work in the field of stream ecology, focusing on stream ecology and its relationship with running water. [2]
Abstract: (1996). Stream Ecology: Structure and Function of Running Waters. Transactions of the American Fisheries Society: Vol. 125, No. 1, pp. 154-158.
1,047 citations
TL;DR: In this article, the present distribution of salmonid fishes in Wyoming streams was found to be limited to regions where mean July air temperatures did not exceed 22°C, and the authors predicted that much of the present salmonid habitat in streams is predicted to be lost if climatic warming occurs.
Abstract: The present distribution of salmonid fishes in Wyoming streams was found to be limited to regions where mean July air temperatures did not exceed 22°C. Much of the present salmonid habitat in streams is predicted to be lost if climatic warming occurs. For increases of 1, 2, 3, 4, or 5°C in mean July air temperature, the geographic area of Wyoming containing suitable salmonid habitat would be reduced by 16.2, 29.1, 38.5, 53.3, or 68.0%, respectively. This loss of geographic range would correspond to reductions of 7.5, 13.6, 21.0, 31.4, or 43.3% in the length of streams having suitable salmonid habitat. In the Rocky Mountain region, increases of 1, 2, 3, 4, or 5°C in mean July air temperature would reduce the geographic area containing suitable salmonid habitat by 16.8, 35.6, 49.8, 62.0, or 71.8%, respectively. As warming proceeds, salmonid populations would be forced into increasingly higher elevations and would become fragmented as suitable habitat for coldwater fish becomes separated from main r...
195 citations
TL;DR: In laboratory experiments, reaction distance of juvenile bluegills Lepomis macrochirus to a predator, largemouth bass Micropterus salmoides, and shifts bybluegills between nearshore and offshore habitats across a turbidity gradient are quantified.
Abstract: Studies of sunfish Lepomis spp. have demonstrated that predation regulates size-specific habitat use and competitive interactions both within and among species. However, all of these studies were conducted in clear-water systems with dense littoral vegetation, resulting in well-defined littoral and open-water habitats. In contrast, little is known about predator–prey interactions among fishes that inhabit turbid lakes and reservoirs. In these systems, turbidity reduces detection (reaction) distance for both predator and prey, and can eliminate submerged vegetation that serves as a refuge. In laboratory experiments, we quantified reaction distance of juvenile bluegills Lepomis macrochirus to a predator, largemouth bass Micropterus salmoides, and determined shifts by bluegills between nearshore and offshore habitats across a turbidity gradient. Bluegill reaction distance declined as a negative power function of turbidity from less than 2 m in clear water to 23 cm at 10 nephelometric turbidity units...
173 citations
TL;DR: A regression model for walleye recruitment in western Lake Erie considered factors such as first-year growth, size of the spawning stock, the rate at which the lake warmed during the spring, and abundance of gizzard shad Dorosoma cepedianum to support contention that mature females needed adequate lipid reserves during the winter to spawn the following spring.
Abstract: In some lakes, first-year growth of walleyes Stizostedion vitreum has been identified as an important factor governing recruitment of juveniles to the adult population. We developed a regression model for walleye recruitment in western Lake Erie by considering factors such as first-year growth, size of the spawning stock, the rate at which the lake warmed during the spring, and abundance of gizzard shad Dorosoma cepedianum. Gizzard shad abundance during the fall prior to spring walleye spawning explained over 40% of the variation in walleye recruitment. Gizzard shad are relatively high in lipids and are preferred prey for walleyes in Lake Erie. Therefore, the high degree of correlation between shad abundance and subsequent walleye recruitment supported the contention that mature females needed adequate lipid reserves during the winter to spawn the following spring. According to the regression analysis, spring warming rate and size of the parental stock also influenced walleye recruitment. Our reg...
141 citations
TL;DR: In this paper, the authors documented the spawning of lake sturgeon Acipenser fulvescens below the Prickett hydroelectric facility on the Sturgeon River, a tributary to Portage Lake, Michigan.
Abstract: Spawning of lake sturgeon Acipenser fulvescens was documented from 1987 to 1992 below the Prickett hydroelectric facility on the Sturgeon River, a tributary to Portage Lake, Michigan. Lake sturgeons were captured at the spawning site with dip nets during periods of reduced flow. A change in the spawning characteristics of the population was noted that corresponded to a change in the operation of the hydroelectric facility. In 1987 and 1988 the facility operated in a peaking mode, which resulted in large daily fluctuations in river flows. The years 1989 and 1990 were years of transition, and in 1991 and 1992 the facility released near run-of-the-river (ROR) flows. Under near-ROR flows, which were more natural, adult lake sturgeons spent 4–6 weeks less at the spawning sites, 74% more fish were observed, weights were greater due to a 68% increase in number of females, and fish had increased reproductive readiness. The change in flow regime was the result of a Federal Energy Regulatory Commission rel...
138 citations
TL;DR: Afflicted Atlantic salmon treated with thiamine by yolk-sac injection or by bath immersion recovered completely from the Cayuga syndrome, as evidenced by the quantified reversal of abnormal swimming behaviors only 2 d after treatment and by the excellent survival of the treated Atlantic salmon through 1.5 months of feeding.
Abstract: A maternally transmitted, noninfectious disease known as the Cayuga syndrome caused 100% mortality in larval offspring of wild-caught landlocked Atlantic salmon Salmo salar from several of New York's Finger Lakes. Survival of lake trout Salvelinus namaycush from Lakes Erie and Ontario was also impaired, but not until yolk absorption was nearly complete; moreover, mortality was greatly reduced relative to that of the salmon (range: 5–87%). Tissue concentrations of thiamine hydrochloride were severely reduced in these salmonid fish relative to unaffected control stocks. Afflicted Atlantic salmon treated with thiamine by yolk-sac injection or by bath immersion recovered completely from the Cayuga syndrome, as evidenced by the quantified reversal of abnormal swimming behaviors only 2 d after treatment and by the excellent survival (>95%) of the treated Atlantic salmon through 1.5 months of feeding. These data represent the first evidence of a vitamin deficiency causing the complete reproductive failu...
134 citations
TL;DR: Laterally compressed panfishes are small and have limited intraperitoneal space; thus, they may suffer adversely from surgically implanted transmitters even if the transmitter meets the generally recommended ratio of transmitter weight to fish weight of 2%.
Abstract: Laterally compressed panfishes are small and have limited intraperitoneal space; thus, they may suffer adversely from surgically implanted transmitters even if the transmitter meets the generally recommended ratio of transmitter weight to fish weight of 2%. We studied the effects of intraperitoneal transmitters (2.81 g) on survival, growth, healing, and health of bluegills Lepomis macrochirus (mean weight 133 g) held for 8 weeks at 6°C and 20°C. Radio-tagged bluegills at 20°C had a mortality rate of 10% and tag loss rate of 15%. At 6°C, bluegills had no mortality or tag loss. Radio-tagged and reference fish fed in both 20°C raceways; however, a few reference fish appeared dominant at feeding time. This dominance by a few reference fish was also indicated by a large weight gain for three reference fish in each 20°C raceway. At 6°C, neither reference fish nor radio-tagged fish fed activity. Radio-tagged fish held at 20°C exhibited pelvic fin erosion, erythema and necrosis at the antenna exit and at...
125 citations
TL;DR: In this article, a wedge-shaped pattern of variation in stream fish standing stock estimates relative to a habitat variable, in which range of standing stocks increases as a function of the variable, is consistent with the concept that the habitat variable is a limiting factor for fish populations.
Abstract: A wedge-shaped pattern of variation in stream fish standing stock estimates relative to a habitat variable, in which range of standing stocks increases as a function of the variable, is consistent with the concept that the habitat variable is a limiting factor for fish populations. This pattern of variation complicates interpretation of parameter estimates and significance of ordinary least-squares (OLS) regression models of conditional mean standing stock; slopes of these regression models may have little or no relation to slopes of models describing standing stock limits. We modeled standing stock limits by testing for homoscedastic error distributions, screening plots of coordinate pairs for evidence of a wedge-shaped pattern of data, and estimating 90th regression quantiles for simple linear models. Application of this technique to data sets supporting 35 previously published OLS regression models of stream fish standing stocks led to rejection of homoscedasticity (P < 0.10) in 13 of the 35 d...
118 citations
TL;DR: Using single-locus microsatellite markers, higher levels of genetic variation than previously reported for northern pike Esox lucius are resolved and this level of genetic variability is much lower than that found for many other fish species by using micros satellite markers.
Abstract: Using single-locus microsatellite markers, we have resolved higher levels of genetic variation than previously reported for northern pike Esox lucius. We isolated 14 (AC) n ·(TG) n microsatellite loci from a genomic library of northern pike. Primer pairs for the polymerase chain reaction (PCR) were developed for nine of these loci. With PCR, a DNA-amplifying technique, we were able to assess genetic variability using fish scales as our source of DNA. In four populations, we found four polymorphic loci with three or four alleles at each locus. Average heterozygosity at all loci was 0.075. Although this level of genetic variability is the highest reported for this species, it is much lower than that found for many other fish species by using microsatellite markers. Small numbers of founder fish, combined with loss of variation due to genetic drift in the small populations typical of northern pike, may explain the relatively low levels of genetic variation we found.
109 citations
TL;DR: The design of fishways and other fish facilities, 2nd edition as discussed by the authors, has been studied extensively in the field of aquaculture and aqua-science, and has been extensively studied in the literature.
Abstract: (1996). Design of Fishways and other Fish Facilities, 2nd edition. Transactions of the American Fisheries Society: Vol. 125, No. 4, pp. 631-631.
108 citations
TL;DR: In this article, the authors conducted laboratory respirometry trials using adult sockeye salmon Oncorhynchus nerka implanted with EMG radio transmitters to investigate the relationship between oxygen consumption and EMG pulse interval.
Abstract: We conducted laboratory respirometry trials using adult sockeye salmon Oncorhynchus nerka implanted with electromyogram (EMG) radio transmitters to investigate the relationship between oxygen consumption and EMG pulse interval. The strong association that was observed suggested that EMG telemetry could be used to assess activity and, thus, relative energy expenditure in freely migrating sockeye salmon. Using EMG telemetry, we then assessed the relative energy costs of upstream migration by adult sockeye salmon through specific reaches of the Fraser River, British Columbia. Greatest energy costs were incurred during migration through Hell's Gate fishways, a known point of difficult passage. Another energetically demanding area was a gravel bar that had not been previously identified as difficult for passage. Three other areas that historically had been identified as difficult for passage were energetically less expensive to migrate through during our study. Our results demonstrate that EMG telemet...
TL;DR: Test the hypothesis that angling during warmer summer months (water temperatures of 20 ± 2°C) increases the magnitude of physiological disturbances in the white muscle by observing marked increases in white muscle lactate and the postexercise metabolic proton load, which accompanied glycogen depletion.
Abstract: Atlantic salmon Salmo salar, returning to freshwater to spawn, were angled and then terminally sampled to test the hypothesis that angling during warmer summer months (water temperatures of 20 ± 2°C) increases the magnitude of physiological disturbances in the white muscle. Angling immediately reduced white muscle ATP and phosphocreatine stores, but these high-energy phosphates were replenished within 2–4 h. Intramuscular glycogen stores were nearly depleted after angling, but unlike the response by salmon angled in the fall at 6°C, there was no glycogen resynthesis during the 4-h recovery period. Marked increases in white muscle lactate and the postexercise metabolic proton load (▵H+ m ) accompanied glycogen depletion. The time course of lactate elimination and ▵H+ m correction, however, was much slower than previously observed in fall-angled salmon. Finally, considerable delayed postangling mortality (40%) was observed in a subgroup of Atlantic salmon that were angled at 22°C. We conclude that ...
TL;DR: This paper examined distribution and habitat characteristics of spawning sites of cutthroat trout Oncorhynchus clarki at various spatial scales to assess effects of sedimentation within a large basin in Montana.
Abstract: We examined distribution and habitat characteristics of spawning sites of cutthroat trout Oncorhynchus clarki at various spatial scales to assess effects of sedimentation within a large basin in Montana. Redd density varied widely across the basin; nearly all (99%) of the 362 redds observed occurred in two high-elevation headwater tributaries. Redd density at the reach scale was positively correlated (r 2 = 0.72, P = 0.001) with abundance of spawning gravels. Other habitat variables, such as gradient, width, depth, embeddedness, bank stability, and percent riffle, were not significantly correlated to redd density. Taylor Fork redds contained some of the highest proportions of fine sediments (<6.35 mm, mean = 41.6%; <0.85 mm, 17.9%) observed in egg pockets of salmonid redds in the Rocky Mountain region. Cache Creek, a highly disturbed subbasin, had significantly greater proportions of fine sediments smaller than 0.85 mm in redds than the undisturbed Wapiti Creek subbasin. High fine-sediment levels...
TL;DR: In this article, the authors evaluated the planning, design and performance of the Riffle 1 B reconstruction on the Merced River and found that the project planning and design did not consider the site's geomorphic context nor processes of erosion and sediment transport under the current flow regime.
Abstract: From 1986 to 1995, over US$2.5 million has been spent or allocated for projects to modify channel conditions to improve spawning habitat for Chinook salmon Oncorhynchus tshawytscha in the Merced, Tuolumne, and Stanislaus rivers, tributaries to the San Joaquin River, California. We evaluated the planning, design and performance of the Riffle 1 B reconstruction on the Merced River. This is typical of the nine individual riffle reconstructions completed to date, involving excavation of the existing channel bed (here, to 0.6 m) and back-filling with smaller gravels believed to be more suitable for salmon spawning. We reviewed project documents, interviewed agency staff, and conducted field surveys to document channel conditions in 1994 for comparison with the project as constructed in 1990. The project planning and design did not consider the site's geomorphic context nor processes of erosion and sediment transport under the current flow regime. As a consequence, spawning-sized gravel placed in the c...
TL;DR: It is believed gizzard shad maximize growth by supplementing their low-protein detritus diet with more zooplankton as more becomes available, which demonstrates that this species is a facultative detritivore.
Abstract: In Ohio reservoirs, larval gizzard shad Dorosoma cepedianum less than 30 mm total length consume only zooplankton but frequently switch to detritus as they grow longer than 30 mm. However, in laboratory studies without detritus, gizzard shad longer than 30 mm consume crustacean zooplankton. To explore the composition of diets of omnivorous 30–100-mm gizzard shad, we completed 1-h laboratory feeding trials with different amounts of zooplankton and detritus and quantified the diets of gizzard shad in reservoirs. In both laboratory and field, gizzard shad ate primarily detritus but also ate zooplankton, consuming more as more became available, which demonstrates that this species is a facultative detritivore. In the field, zooplankton consumption declined as gizzard shad body size increased. We believe gizzard shad maximize growth by supplementing their low-protein detritus diet with more zooplankton as more becomes available. With this strategy, omnivorous gizzard shad may compromise the potential ...
TL;DR: A 10-page mail questionnaire was sent to a stratified random sample of 9,981 Texas fishing license holders and a response rate of 62% was obtained (exclusive of questionnaires that could not be delivered). Adjustments for nonresponse were made by means of response propensity stratification as mentioned in this paper.
Abstract: Angler surveys can yield inaccurate results because of the failure of some anglers to participate or return their questionnaires. If nonrespondents are different from respondents with respect to the variables in the survey, some segments of the angler population will be under- or overrepresented, and the inferences made from the respondents about the population of interest will be subject to nonresponse bias. Errors introduced by nonresponse can be greater than sampling error, making it impossible to assign useful confidence limits to survey results. A 10-page mail questionnaire was sent to a stratified random sample of 9,981 Texas fishing license holders. Information was collected on fishing experience, fishing participation, species preferences, attitudes, and orientation to fisheries management efforts. A response rate of 62% was obtained (exclusive of questionnaires that could not be delivered). Adjustments for nonresponse were made by means of response propensity stratification. Individual r...
TL;DR: Freshwater-acclimated subadult striped bass Morone saxatilis that had undergone cannulation of the dorsal aorta were exercised against a water current at 100 cm·sec−1 for 5 min in freshwater and placed in flow-through holding boxes in a recovery tank at 25°C.
Abstract: Freshwater-acclimated subadult striped bass Morone saxatilis that had undergone cannulation of the dorsal aorta were exercised against a water current at 100 cm·sec−1 (2–3 fork lengths·sec−1) for 5 min in freshwater and placed in flow-through holding boxes in a recovery tank at 25°C. Recovery tanks contained water with either 0 (freshwater, FW), 10 (brackish water, BW), or 30 (seawater, SW) g NaCl·L−1 or 10 mM NaHCO3 −·L−1 (buffered freshwater, BFW). A postexercise metabolic acidosis (decreased postexercise blood pH and increased blood lactate) was compensated within 2–4 h in all recovery environments except SW. Arterial O2 tension and cortisol, glucose, and hemoglobin concentrations transiently increased immediately after exercise, and arterial CO2 tension and HCO3 − generally decreased. Plasma Cl− did not change until 2–4 h postexercise, when decreases (FW and BFW), an increase (SW), or no change (BW) indicated passive fluid or Cl− exchanges with the recovery environment. Increasing plasma Cl− ...
TL;DR: This model predicted long-term hooking mortality of striped bass after catch and release in saltwater using a logistic regression model and included depth of hook penetration, gear type, and angler experience as predictor variables.
Abstract: Despite the importance of the recreational fishery for striped bass Morone saxatilis along the eastern coast of the United States, little is known about the survival rates of caught and released striped bass. We predicted long-term (58-d) hooking mortality of striped bass after catch and release in saltwater using a logistic regression model. Experimental fishing was conducted on fish (27–57 cm) in a 2-ha saltwater impoundment in Salem, Massachusetts. Depth of hook penetration in the oral cavity, anatomical site of hooking, gear type (treble or single hooks), and angler experience were significantly related to mortality (P < 0.05). The logistic regression model was developed with backwards stepwise selection to predict probability of death from hooking. The final model included depth of hook penetration, gear type, and angler experience as predictor variables. Predicted mortality ranged from 3% under the most favorable conditions to 26% for the worst set of conditions. Predicted as well as observ...
TL;DR: The theoretical and empirical models suggest that overwinter mortality of white perch is caused primarily by starvation at 4.0°C and by osmoregulatory dysfunction as well as starvation at 2.5°C.
Abstract: We evaluated the relative importance of energy depletion and osmoregulatory stress as possible mechanisms regulating overwinter mortality of age-0 white perch Morone americana. Fish used less energy, took up more water, and had much higher mortality at 2.5°C than at 4.0°C. Mortality, energy use, and water uptake were all related to body size. Relationships of empirically derived endurance time (ET, days to 50% mortality) to body mass were allometric with weight exponents of 0.29 at 2.5°C and 0.77 at 4.0°C. Theoretically derived weight exponents were 0.82 for ET models based on starvation and 0.18 for models based on osmotic mechanisms. The theoretical and empirical models suggest that overwinter mortality of white perch is caused primarily by starvation at 4.0°C and by osmoregulatory dysfunction as well as starvation at 2.5°C.
TL;DR: In this paper, the authors developed an index of biotic integrity and a biotic index based on fish species richness to assess the ecological health of streams on the Savannah River Site, a 780-km2 U.S. Department of Energy facility located in the Sand Hills ecoregion on the upper coastal plain of South Carolina.
Abstract: We developed an index of biotic integrity (IBI) and a biotic index based on fish species richness (FSBI) to assess the ecological health of streams on the Savannah River Site, a 780-km2 U.S. Department of Energy facility located in the Sand Hills ecoregion on the upper coastal plain of South Carolina. To maintain the responsiveness of the IBI to a variety of impacts yet incorporate sufficient ecoregion specificity to achieve acceptable accuracy, we included metrics from each of six metric categories proven useful in other ecoregions (species number, species composition, trophic composition, local indicator species, fish abundance, and fish condition) but selected specific metrics within each category based on their ability to discriminate between disturbed and undisturbed sites in the Sand Hills ecoregion. We also developed a procedure based on species–area curves to remove the potentially confounding effects of site-specific differences in sample unit size and sampling effort from species number...
TL;DR: Marking success and mortalities were similar for ARS and AC in comparable treatments, and alizarin red S marks were retained for at least 160 d.
Abstract: We compared marking success for larval and juvenile fishes immersed in alizarin red S (ARS) to that of fish immersed in alizarin complexone (AC). Postlarval and juvenile central stonerollers Campostoma anomalum and southern redbelly dace Phoxinus erythrogaster and larval white suckers Catostomus commersoni were immersed in ARS or AC at concentrations of 50–400 mg/L for 6–24 h. Both chemicals imparted a violet-red mark, visible in the whole otoliths under a bright-field light source. Immersion in ARS at 200–300 mg/L for 12 or 24 h resulted in optimal marking success (100%) and minimal mortalities (0–3%). Marking success and mortalities were similar for ARS and AC in comparable treatments. Alizarin red S marks were retained for at least 160 d.
TL;DR: It is argued that EMG biotelemetry, combined with location tracking, may be a versatile tool for application to a wide variety of problems in fisheries biology, including the study of physiological energetics...
Abstract: Electromyogram (EMG) biotelemetry was used to assess activity patterns for adult free-swimming largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu. We first conducted laboratory respirometry trials and found a strong association between EMG signal and swimming activity which indicated that EMG biotelemetry could be used to assess activity of wild fish. A field study confirmed that both species exhibit diurnal activity patterns. When EMG activity was compared with estimates of swimming activity from location tracking, elevated EMG activity was often recorded for apparently stationary fish. These observations suggested that fish activity at spatial and temporal scales too small for detection by location tracking may account for a significant proportion of daily activity. We argue that EMG biotelemetry, combined with location tracking, may be a versatile tool for application to a wide variety of problems in fisheries biology, including the study of physiological energetics...
TL;DR: One of the few remaining fisheries for Atlantic sturgeon Acipenser oxyrinchus takes place during spring and fall in the New York Bight, but no information on the stock composition of this fishery is available.
Abstract: One of the few remaining fisheries for Atlantic sturgeon Acipenser oxyrinchus takes place during spring and fall in the New York Bight, but no information on the stock composition of this fishery is available. We used data from mitochondrial DNA (mtDNA) restriction fragment length polymorphism analysis to estimate the relative contributions of source stocks of Atlantic sturgeon to a New York Bight fishery sample (N = 112) collected in 1993 and 1994. Composite mtDNA haplotype frequencies of source populations were first characterized with five informative restriction enzymes: Bgl I, Msp I, EcoR V, Hinf I, and Hinc II. All St. Lawrence River, Quebec, and St. John River, New Brunswick, specimens had an identical haplotype (genotypic diversity = 0.0); for the purposes of mixed-stock analysis, both populations were pooled as the “Canadian stock.” Genotypic diversity ranged between 0.483 and 0.750 among samples from the Hudson River in New York, the Edisto River in South Carolina, and the Ogeechee, Alt...
TL;DR: Bootstrap simulations show that the chance location of transects in PHABSIM studies can introduce such great uncertainty into the resulting curves of WUA over discharge that the curves can be meaningless.
Abstract: The physical habitat simulation model (PHABSIM) produces curves showing the relation between flow and habitat that are often used as evidence for decisions on the management of water resources. The curves show values of “weighted usable area” (WUA) over discharge. Minimum confidence intervals for the curves can be developed with the bootstrap method if transects are randomly located within sampling units. This is illustrated with bootstrap simulations that develop minimum confidence intervals for several model rivers, defined in terms of sampling procedures and values of WUA for juvenile chinook salmon Oncorhynchus tshawytscha at 15 transects on the Feather River, California. The simulations show that the chance location of transects in PHABSIM studies can introduce such great uncertainty into the resulting curves of WUA over discharge that the curves can be meaningless. Therefore, it is crucial that confidence intervals be developed for curves of WUA over discharge before PHABSIM results are pre...
TL;DR: This work analyzed depositional patterns of trace elements in the otoliths of adult Lentipes concolor, an amphidromous goby endemic to Hawaii, to determine whether landlocked forms occurred and demonstrated a transition from a marine phase to freshwater existence.
Abstract: Tropical streams on high oceanic islands are characterized by populations of amphidromous gobioid fishes. Adult fish live and breed in freshwater and many spawn at high (>300 m) elevations. Newly hatched fry are swept down to the sea where they develop for a period of time before recruiting to a stream. In analogous habitats in other geographic areas, amphidromous populations have further evolved into landlocked forms (i.e., populations that spend their entire life cycle in freshwater). We analyzed depositional patterns of trace elements in the otoliths of adult Lentipes concolor, an amphidromous goby endemic to Hawaii, to determine whether landlocked forms occurred. Otoliths were obtained from fish collected from the Hawaiian stream habitats most likely to harbor landlocked populations—upper elevations of interrupted streams and sections of streams above high waterfalls. A transition from a marine phase to freshwater existence was demonstrated as a decrease from high to low strontium : calcium r...
TL;DR: To determine if the parasite was present in natural populations of eels in North America, wild eels from five Texas rivers and Winyah Bay, South Carolina were examined and no swim bladder parasites were found, but one eel from South Carolina was infected with an immature Anguillicola crassus.
Abstract: In February 1995, the Texas Parks and Wildlife Department investigated a south Texas aquaculture facility raising eels for sale in Asian markets. There was concern that the eels were infected with Anguillicola crassus, a parasitic swim bladder nematode detrimental to fisheries for European eel Anguilla anguilla after its introduction from Asia in the early 1980s. Eight of 23 eels examined at the facility were infected with a total of 104 Anguillicola crassus. To determine if the parasite was present in natural populations of eels in North America, wild eels from five Texas rivers (N = 22) and Winyah Bay, South Carolina (N = 8) were examined. No swim bladder parasites were found in the eels from Texas, but one eel from South Carolina was infected with an immature Anguillicola crassus.
TL;DR: Walleyes that were the offspring of broodstock from the river-spawning population were captured more frequently in lotic habitat well upstream from the impoundment, whereas offspring of the lake-spawned population were found morerequently in lake habitat, consistent with the hypothesis that choice of spawning habitat has a heritable component.
Abstract: The basis of behavioral differences between populations of river- and lake-spawning walleye Stizostedion vitreum was evaluated. We used fish from one population that migrates up a river to spawn on gravel bars and from another that remains in a lake to spawn on rocky shoals as broodstock to produce genetically tagged fry of each stock. Offspring from these broodstocks were introduced into a system containing both habitats. When the stocked walleyes had reached sexual maturation 3 and 4 years later, adults in reproductive condition were collected throughout the impoundment–river system. Walleyes that were the offspring of broodstock from the river-spawning population were captured more frequently in lotic habitat well upstream from the impoundment, whereas offspring of the lake-spawning population were found more frequently in lake habitat. This result is consistent with the hypothesis that choice of spawning habitat has a heritable component: walleyes have a genetically based response to environm...
TL;DR: In this paper, the authors compared three proportional back-calculation methods for scales using data sets for pumpkinseeds Lepoinis gibbosus and golden shiners Notemigonus crysoleucas from 10 southern Quebec lakes.
Abstract: We compared three proportional back-calculation methods for scales using data sets for pumpkinseeds Lepoinis gibbosus and golden shiners Notemigonus crysoleucas from 10 southern Quebec lakes, and we validated back-calculations by comparing them with observed lengths at time of annulus formation. Ordinary least-squares regression (OR) was compared with geometric mean regression (GMR) for describing body–scale relationships. Although minor differences were detected in body–scale regressions among lakes, pooling data across lakes yielded linear body–scale relationships with very high r 2. Differences between OR and GMR body–scale relationships were negligible in both species. Likewise, all back-calculation methods produced equivalent results. Back-calculated lengths generally corresponded well with observed lengths in all pumpkinseeds age-classes and in golden shiners older than l year. Observed lengths were often greater than back-calculated lengths for age-1 golden shiners. Our results, indicating...
TL;DR: In this article, the possible existence of purely marine populations of barramundi in waters adjoining the Mary River system was examined through a chemical analysis of scales by means of inductively coupled plasma atomic emission spectroscopy.
Abstract: The barramundi Lates calcarifer is a large centropomid fish that utilizes freshwater and saltwater habitats and is generally regarded as catadromous. It is fished commercially in coastal waters in northern Australia. It is also a popular recreational species in fresh and estuarine waters, and has been the subject of a resource allocation controversy in recent years. The possible existence of purely marine populations of barramundi in waters adjoining the Mary River system was examined through a chemical analysis of scales by means of inductively coupled plasma atomic emission spectroscopy. Discriminant function analysis with control fish reared in freshwater and salt water showed that wild barramundi could be classified reliably by barium and strontium levels, which are related to environmental history. Cluster analysis indicated that there were probably marine, mixed, and freshwater groups. We conclude that most barramundi found in areas remote from freshwater parts of the Mary River system prob...