Effects of angling with a single-hook and live bait on muskellunge survival

Use of live bait for angling of muskellunge, Esox masquinongy, is popular in Wisconsin. A traditional method utilizes a large hook through the bait fish’s snout, which requires the muskellunge to swallow the bait prior to hook set. Adult muskellunge (>76 cm; 30 in) were held in lined hatchery ponds and caught while fishing with live bait on 10/0 size single hooks. The leader was cut and the muskellunge was released when hooked in the stomach. Survival was monitored for up to 1 year. No immediate ( <24 h) mortality occurred. However, 22% of hooked muskellunge died within 50 days and 83% died within 1 year. Necropsies revealed extensive trauma to the stomach and other organs from hooks, along with systemic bacterial infections. Highest mortality on both hooked and control fish occurred over winter through spring. This peak mortality may be associated with natural stressors that occur during the spring spawning period. Mortality rates observed in this study are considered unacceptable for trophy management of muskellunge. Although use of live bait for muskellunge is traditional in Wisconsin, terminal tackle such as quick-strike rigs that hook fish in the mouth or buccal cavity should enhance the chances a released muskellunge will survive.     

Displacement,and home range movements of muskellunge determined by ultrasonic tracking

Synopsis Five adult or subadult muskellunge, Esox masquinongy (Salmoniformes: Esocoidei), were tracked over periods of 6–11 days by means of ultrasonic (74 ± 1 Khz) transmitters, surgically implanted in the body cavity. One of these fish demonstrated that survival and well-being for over a year is probable. There was no apparent effect on equilibrium, swimming, or feeding. There was also no apparent abnormally high amount of movement immediately after release.Signal range was at times no greater than 10 m (in contrast to a potential of 1 km) as a result of the air in the dense aquatic vegetation.Area occupied by a single individual for a protracted period could be described as a linear distance of 300–800 m in the stream, or a circle 300 m in diamter in the lake. Displaced individuals returned to a specific locality. Following spawning they do so over a distance as great as 6.4 km in a maximum of two days. There was evidence that two individuals used the same general area simultaneously.Subsequent results with some of the same individuals indicated that radio transmitters are more practical and yield better results in the situation under study.     

The New River, Virginia, muskellunge fishery: population dynamics, harvest regulation modeling, and angler attitudes

Although muskellunge, Esox masquinongy, fisheries in northern US states and Canadian provinces are increasingly being managed by introduction of restrictive harvest regulations (e.g. 1370-mm (54′′) minimum length limits), many southern US muskellunge fisheries continue to be managed with comparatively liberal regulations (e.g. 762-mm (30′′) minimum length limits) that are implemented statewide. We studied the population dynamics of the New River, Virginia, muskellunge fishery and used predictive modeling to determine whether restrictive harvest regulations also might prove beneficial for this southern latitude fishery. A creel survey was also conducted to learn more about angler attitudes to the New River muskellunge fishery. Muskellunge grew quickly, with fish reaching harvestable lengths (762 mm, 30′′) in 2–3 years. Muskellunge fishing pressure, harvest rates, and voluntary release rates were low compared with reports for more northern areas. Most anglers, irrespective of how often they fished for muskellunge, defined “trophy” muskellunge to be approximately 1050–1100 mm (41–43′′) in length. Although angler support for restrictive harvest regulations was low, abundance of memorable-length (≥1070 mm, 42′′) muskellunge was predicted to increase under all evaluated length limits. Muskellunge yield would remain static at 914-mm (36′′) and 1016-mm (40′′) length limits, because of the rapid growth of fish, but yield would decline dramatically with a 1143-mm (45′′) length limit, because male muskellunge rarely exceeded 1100 mm (43′′). Because of rapid growth and low release rates, implementation of higher length limits (e.g. 965–1067 mm, 38–42′′) may indeed prove beneficial for augmenting “trophy” muskellunge production on the New River. Angler support for higher minimum length limits might be increased by educating anglers about the rapid growth rates of muskellunge and the expected size structure changes that will result from a length-limit increase. Size structure changes resulting from an increase in the minimum length limit may be difficult to detect because of potential increases in fishing pressure or reduced fish growth as a result of competition for food resources. Long-term monitoring of muskellunge growth and angling pressure may therefore be needed to ensure that new regulations are indeed benefitting the fishery.     

The use of angler diary surveys to evaluate long-term changes in muskellunge populations on Lake of the Woods, Ontario

Reported improvements in the muskellunge angling fishery on Lake of the Woods, Ontario over the last two decades have paralleled an increase in the practice of catch and release angling, and an increase in minimum size regulations for this species. The overall status of muskellunge populations in this large, complex lake has proven difficult to monitor using standard assessment methods. A volunteer muskellunge angler diary program, established in 1988, has provided a cost effective method of gathering a large amount of information with which to track this fishery and associated populations. Results from angling diaries indicated increased angling effort, catch and success rates for muskellunge on Lake of the Woods since the early 1990s. Although the month of July accounted for the majority of angling effort and catch, angling success rates and sizes of fish reported in diaries improved monthly into the late fall. Angling success rates were consistently higher in angling diaries than from creel surveys, but both survey types showed similar long-term trends in the fishery. Angler diary data, incorporating both the numbers of fish caught and/or seen by anglers, were used to calculate catch equality indices which proved to be sensitive to changes in population abundance. Increased minimum length regulations for muskellunge during 1987–2001 have been largely responsible for a decline in harvest rates from an estimated 36% in 1986 to 0% since 1999. Although higher size limits have yet to produce more quality-sized fish in angler catches, diary survey data, supported by recent improvements in catch rates from assessment gill nets, would indicate that muskellunge recruitment has increased. This article concludes with a brief review of how muskellunge angler diary data has been used in the past, including recommendations to minimize biases associated with this survey method.     

Vegetative growth inRumex acetosella (Polygonaceae) originating from different geographic regions

Vegetative growth patterns ofRumex acetosella L. were investigated both in experimental conditions and in the field. Plants originating from geographically and ecologically contrasting areas expressed significant differentiation in height, weight, and leaf production, even at early stages. The plants belonging to subsp.angiocarpus grew thaller than other plants. The differences among populations grown in a uniform environment provide evidence for genetic differentiation in morphology. Plants in natural populations were considerably lighter than experimental plants, which intensively produced a large number of rosette leaves. These differences can be attributed to substantial phenotypic plasticity. When the correlation structure among the growth traits was analyzed, seed weight and early plant size appeared to influence future plant size.     

Comparative water relations of adult and juvenile tortoise beetles: differences among sympatric species

Relative abundance of two sympatric tortoise beetles varies between drought and 'wet' years. Differing abilities to conserve water may influence beetle survival in changing environments. Cuticular permeability (CP), percentage of total body water (%TBW), rate of water loss and percentage of body lipid content were determined for five juvenile stages and female and male adults of two sympatric species of chrysomelid beetles, the golden tortoise beetle, Charidotella bicolor (F.) and the mottled tortoise beetle, Deloyala guttata (Olivier). There were significant differences in %TBW and lipid content among juvenile stages. Second instars had the greatest difference in CP (37.98 and 11.13 microgcm(-2)h(-1)mmHg(-1) for golden and mottled tortoise beetles, respectively). Mottled tortoise beetles had lower CP and greater %TBW compared with golden tortoise beetles, suggesting that they can conserve a greater amount of water and may tolerate drier environmental conditions. This study suggests that juvenile response to environmental water stress may differentially affect the survival of early instars and thus affect the relative abundance of adult beetles in the field. This is supported by the low relative abundance of golden tortoise beetle larvae in a drought year and the higher abundance in two 'wet' years.     

An apparatus for sampling gut contents of large,living fishes

Synopsis Apparatus and methods are described and illustrated for flushing and retaining gut contents from large, living fishes with water supplied by a 12 volt portable pump.     

Distribution of isoasparagine among different characean species

Thirteen species of Characeae were analyzed for their free amino acid contents. Large amounts of isoasparagine, accounting for 10 to 50% of the total free amino acids, were found in extracts fromChara (5 species including one unidentified),Nitellopsis (1 species), andLamprothamnium (1 species). In contrast, no isoasparagine was detected inNitella (5 species) andTolypella (1 species), except forN. flexilis in which as much as 40% of the free amino acids was isoasparagine. Other major amino acids found in the tested materials were Ala, Asp, Glu and Gln.     

Genetic diversity among sublines originating from a single somatic hybrid cell of Duboisia hopwoodii + Nicotiana tabacum

Summary The genetic instability of an intertribal hybrid cell line, Duboisia hopwoodii + Nicotiana tabacum, obtained by mechanical isolation of a single hybrid cell was studied. Ten subclones of calli derived from this hybrid cell line were cultured for 3 years, and their genetic makeup clarified as to nuclear DNA content, chromosome constitution, and peroxidase isozymes. Nuclear DNA content differed in each subclone. In most subclones, mean DNA content was lower than the mean DNA content in the original hybrid cell line determined 1 year after fusion. This decrease in DNA content is partly attributable to the elimination of tobacco chromosomes that occurred in all subclones. The extent to which tobacco chromosomes were eliminated varied among the subclones — evidence that chromosome elimination occurred slowly. Peroxidase isozyme analysis indicated the loss of a tobacco-specific isozyme, thus confirming results obtained by chromosome analysis. Shoots regenerated from two hybrid subclones after 2 years were also heterogeneous in morphology and nuclear DNA content.     

Differences in surface behaviour of galactolipoids originating from different kind of wheat tissue cultivated in vitro

The aim of presented researches was to investigate the physicochemical properties of Langmuir monolayer of galactolipids extracted from two different kinds of plastids: immature embryos and inflorescences. Differences between the physicochemical properties of the plastid membranes may help to explain different physiological processes, such as plant regeneration. Surface pressure (pi) vs. molecular area (A) isotherms of the monogalactosyldiacylglycerol (MGDG)/digalactosyldiacylglycerol (DGDG) monolayers of various molar ratios were measured at 15 degrees C. Galactolipids were extracted from two different types of tissue: inflorescences and embryos. Based on the analysis of the pi-A isotherms, the properties of monolayers, such as collapse pressure (pi(coll)), limiting area (A(lim)), compressibility modulus (C(s)(-1)), excess free energy of mixing (DeltaG(EXC)) and free energy of mixing (DeltaG(MIX)), were calculated. The results show that pure MGDG and DGDG and their mixtures form liquid-expanded monolayers, independently on the kind of tissue. Galactolipids originating from inflorescences produce more compressible films at the air/water interface, with larger limiting area per molecule and lower stability against the collapse process. MGDG and DGDG are miscible and form non-ideal mixed monolayers at the air/water interface. Negative values of DeltaG(EXC) were calculated for the mixture of galactolipids originating from inflorescences, with the content of MGDG, x(MGDG)>0.6. In the case of embryos, the negative values of DeltaG(EXC) were found for x(MGDG) approximately 0.5. Therefore, the attractive interactions between MGDG and DGDG exist in the mixtures of these compositions. As it is shown by negative values of DeltaG(MIX), mixed monolayers are more stable compared with unmixed ones.     

Localized temperature adaptation of cottonwoods from elevational ecoregions in the Rocky Mountains

To investigate temperature adaptation of cool-climate trees, we studied 14 cottonwood genotypes from riparian (streamside) zones in three ecoregions differing in elevation in the Rocky Mountains of Alberta, Canada. Black cottonwoods (Populus trichocarpa) were collected from the higher, cooler montane and intermediate (aspen) parkland, and narrowleaf cottonwoods (P. angustifolia) were collected from the lower, warmer fescue prairie. The genotypes were grown in growth chambers under three temperature regimes reflecting the ecoregion variation. Sapling growth (dry weight) varied significantly across temperatures and for the genotypes from within and particularly across the ecoregions. Significant temperature × genotype interactions further indicated differentiation of the temperature response. Growth of the montane clones increased by 209% between 15/10 and 20/15°C and was 37% lower at 25/20°C. In contrast, genotypes from the lower ecoregions grew more slowly at the cool and intermediate temperatures (59 and 58% of montane) and then demonstrated constant (−3% parkland) or slightly increased (+16% prairie) growth at 25/20°C. This suggests the existence of P. trichocarpa ecotypes, localized populations with different temperature responses. This differentiation may explain our previous observation of comparable growth across these ecoregions despite substantial temperature variation, and the existence of ecotypes would produce a range of responses to climate warming that should produce an upward shift of the mountain ecoregions.     

The growth of juvenile snails in water conditioned by snails of a different species

Summary Two species of freshwater snails, Physa acuta and Lymnaea sp. aff. columella, were collected from Asabata marsh, Shizuoka Japan. Individuals of both species inhabit the same plants. Individuals of P. acuta are more abundant than those of L. sp. aff. columella. Experiments were conducted to examine the effect of water conditioned by snails on the growth of 10-day-old juvenile P. acuta snails. Juvenile snails in water conditioned by L. sp. aff. columella grew faster than those in water conditioned by P. acuta or only lettuce. The effects of water conditioned by P. acuta differed among the litters. The results suggest that juvenile P. acuta snails experience accelated growth in the presence of L. sp. aff. columella. The freshwater snails interacted through resource competition as well as through substances disolved in the water.     

Differences in cold tolerance,desiccation resistance,and cryoprotectant production between three populations of <Emphasis Type="Italic">Eurosta solidaginis</Emphasis> collected from different latitudes

Possible links between cold-tolerance and desiccation resistance were examined between larvae of the goldenrod gall fly collected from Michigan, southern Ohio, and Alabama locations as their host plant senesced. After acclimation to 5°C, Michigan-collected larvae were more cold-tolerant (25% survival after a 96 h exposure to −40°C) than larvae from Ohio (10% survival) and Alabama (0% survival). Increased cold-tolerance was partially linked to higher concentrations of the cryoprotectant glycerol (Michigan: 500 ± 30 mmol; Ohio: 270 ± 20; Alabama: 220 ± 20). Moreover, cryoprotectants may have functioned to reduce rates of overall and cuticular water loss for Michigan larvae, 0.10 ± 0.01 and 0.037 ± 0.003 μg mm⁻² h⁻¹, respectively, values that were 40-44% lower than those for Ohio and Alabama larvae and may represent a link between desiccation resistance and cold-tolerance. After acclimation to 20°C, Alabama-collected larvae had metabolic rates that were 40% lower than those from Ohio and Michigan that averaged 0.100 ± 0.006 μl of CO₂ produced g⁻¹ h⁻¹. The lower metabolic rate of Alabama-collected larvae at 20°C likely resulted in reduced respiratory transpiration that may represent a mechanism to maintain water balance at the higher overwintering temperatures they typically experience.     

Respiration of different stages and energy budgets of juvenile brachionus calyciflorus

Respiration data for different stages of Brachionus calyciflorus, fed with three concentrations of Kirchneriella lunaris at 20°C, are presented. Increasing oxygen consumption from 4.1 to 4.6 .10^–3 µl/h × ind. with food decreasing from 5.10⁶ to 10⁶ and 4.10⁵ cells/ml has been fourid for adult females with one egg, but other age groups showed divergent results. Based on the respiration data for age groups o to 12 and 12 to 24 h old and some other results and calculations-e.g. dry weight and caloric content of eggs and females, ingestion rates/h for the different concentrations of food-energy budgets for juvenile, growing B. calyciflorus are presented.     

Transposable elements ofXanthomonas campestris pv.citri originating from indigenous plasmids

Summary After introduction of the broad host range plasmid RP4 inXanthomonas campestris pv.citri strain XAS4501 twoXanthomonas transposable elements, ISXC4 and ISXC5, were isolated. These elements were found to be capable of transposition inEscherichia coli. Restriction analysis, DNA hybridization and heteroduplex experiments revealed that ISXC4 and ISXC5 are about 5.55 and 6.95 kb in size, respectively, possess inverted repeats about 50±18 bp in length and share DNA homology in their left (5.0 kb) and right (0.6 kb) ends. ISXC4 and ISXC5 were found to originate from plasmids pXW45N and pXW45J, which are indigenous replicons inX. campestris pv.citri strain XW45.     

Speed of nodulation and competitive ability among strains of Rhizobium leguminosarum bv phaseoli

This study examines the speed of nodulation of 20 strains of Rhizobium leguminosarum bv phaseoli, and relates this trait to the competitive performance of these strains with Phaseolus vulgaris L. At 25/20°C day/night temperature, and with 10⁷ cells applied per growth pouch, there was a strong positive correlation between the speed of nodulation and the competitiveness of strains with the nod⁺ fix^– reference strain UMR 1116. Strains UMR 1084, 1125, 1165, 1173 and 1384 combined good competitive performance with extensive nodulation in the uppermost root regions. When inoculant levels in the RTM studies were reduced to 10³ cells per pouch no correlation between the apparent competitiveness of strains and their speed in nodulation was evident, presumably because cells had to undergo multiplication before infection. Nodulation was also delayed when growth temperatures were raised to 31/26°C, but a correlation was still evident between competitive performance and nodulation in the region 0.1 to 5.0 mm below the RTM at the time of inoculation. From these results speed of nodulation can be used to estimate the competitive potential of Rhizobium strains, but only under carefully regulated conditions. The effects of inoculation level and temperature on the relationship between speed of nodulation and strain competitiveness could explain the inconsistent results obtained in earlier studies on this topic.Journal paper No. 16962, Agricultural Experiment Station, University of Minnesota, St. Paul, MN 55108, USA     

Food web manipulation in a small,eutrophic Lake Wirbel,Poland: effect of stocking with juvenile pike on planktivorous fish

In a four year experiment (1988–1991) carried out in a shallow, eutrophic lake, an increase in young-of-the-year pike (Esox lucius) density was used to control planktivorous fish assemblages consisting mainly of small-sized cyprinids: roach (Rutilus rutilus), Leucaspius delineatus, and white bream (Blicca bjoerkna). Stocking with pike fry of ca 30 mm in three successive springs resulted in large-scale mortality among prey of vulnerable sizes. Rotenone treatment at the end of the fourth year showed that roach and white bream populations contained few 0+ to 2+ fish, but very high numbers of 3+ to 6+ fish. By this time, short-lived, slow-growing L. delineatus, with no size refuge from predators, had been driven almost to extinction.     

Subunit exchange between lectins from different cereal species

Lectins from Triticum monococcum, Secale cereale (rye), and Hordeum vulgare (barley) can exchange their subunits in vitro and thereby form (intergeneric) heteromeric lectins. An analysis of the isolectin pattern of a Triticale variety revealed that intergeneric heterodimers of wheat and rye lectin subunits are normal constituents of the embryo cells. It appears, therefore, that these different cereal lectins are structurally so closely related that their subunits can not distinguish between identical and nonidentical partners when they associate into dimers.Abbreviations CL cereal lectin - SP Sephadex sulfopropyl Sephadex - WGA wheat germ agglutinin     

Fine structure of flight muscles in different Notch mutants of Drosophila melanogaster reared at different temperatures

Summary The fine structure of the indirect flight muscles was studied by electron microscopy in the following Notch locus mutants of Drosophila melanogaster reared at 18° C or 29° C for 6 days after eclosion: Ax ¹⁶¹⁷²/Ax¹⁶¹⁷², Ax²⁸/ Ax²⁸, l(1)N^ts1/l(1)N^ts1,l(1)N^ts1/Y and in wild-type controls. The flies were raised up to eclosion at 25° C or 18° C. It was observed that the l(1)N^ts1 flies gradually became flightless within a few days if reared at 29° C as adults, and gross changes in the fine structure of the flight muscles were also observed in flies of this genotype. Peripheral myofilaments of myofibrils were disarranged and the mitochondria diminutive. At 18° C the flight muscles remained normal. In all of the Abruptex (Ax) combinations the flight muscles remained similar to the wild-type controls at both 18° C and 29° C, i.e. they were normal. The results suggest that the Notch gene is active in adult flies in addition to its activity during embryonic, larval and pupal stages, and is directly or indirectly involved in the adult development of the muscle tissue.     

Serological differences in two Blastomyces dermatitidis isolates from different geographical regions of North America

Yeast phase lysate antigens were prepared from two isolates (T-58 and ERC-2) from different geographic locations, Tennessee and Wisconsin. These lysate were evaluated with respect to their ability to detect antibody in dogs infected with blastomycosis and rabbits immunized with the lysates by an enzyme linked immunosorbent assay (ELISA). Both the dog sera and rabbit sera assays demonstrated that there were serological differences in these two isolates, which implied that there was antigenic variance in geographical populations of B. dermatitidis. These results correlated with a previous molecular study that indicated that there are genetic differences in different geographical populations of the organism. This revised version was published online in June 2006 with corrections to the Cover Date.