scholarly journals Trapping for invasive crayfish: comparisons of efficacy and selectivity of baited traps versus novel artificial refuge traps

2018 ◽  
pp. 15 ◽  
Author(s):  
Nicky Green ◽  
Matt Bentley ◽  
Paul Stebbing ◽  
Demetra Andreou ◽  
Robert Britton
Keyword(s):  
Ecological Impacts ◽  
Catch Per Unit Effort ◽  
Metal Base ◽  
Baited Traps ◽  
Trapping Method ◽  
Invasive Crayfish ◽  
Trapping Methods ◽  
Body Sizes ◽  
The Mean ◽  
Native Crayfish

Non-native crayfish can dominate the invertebrate biomass of invaded freshwaters, with their high ecological impacts resulting in their populations being controlled by numerous methods, especially trapping. Although baited funnel traps (BTs) are commonly used, they tend to be selective in mainly catching large-bodied males. Here, the efficacy and selectivity of BTs were tested against an alternative trapping method based on artificial refuges (ARTs) that comprised of a metal base with several tubes (refuges) attached. The target species was signal crayfish Pacifastacus leniusculus in an upland river in southwest England. Trapping was completed in April to October over two consecutive years. In total, 5897 crayfish were captured, with 87% captured in ARTs. Comparison of the catch per unit effort (CPUE) between the trapping methods in the same 24 hour periods revealed significantly higher CPUE in ARTs than of BTs. ARTs fished for 6 consecutive days had higher catches than both methods over 24 hours. Whilst catches in BTs were significantly dominated by males (1.49M:1F), the sex ratio of catches in ARTs was 0.99M:1F. The mean carapace length of crayfish was also significantly larger in BTs (43.2 ± 0.6 mm) than in ARTs (33.6 ± 0.2 mm). Thus, ARTs had higher CPUE over 24 hour and 6 day periods versus BTs and also captured a greater proportion of smaller and female individuals. These results indicate that when trapping methods are deployed for managing invasions, the use of ARTs removes substantial numbers of crayfish of both sexes and of varying body sizes.

scholarly journals Modeling of Lake Malombe Annual Fish Landings and Catch per Unit Effort (CPUE)

Forecasting ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 39-55
Author(s):  
Rodgers Makwinja ◽  
Seyoum Mengistou ◽  
Emmanuel Kaunda ◽  
Tena Alemiew ◽  
Titus Bandulo Phiri ◽  
...  
Keyword(s):  
Time Series ◽  
Information Criterion ◽  
Coefficient Of Determination ◽  
Series Data ◽  
Efficiency Coefficient ◽  
Arima Models ◽  
Catch Per Unit Effort ◽  
Annual Fish ◽  
Unit Effort ◽  
The Mean

Forecasting, using time series data, has become the most relevant and effective tool for fisheries stock assessment. Autoregressive integrated moving average (ARIMA) modeling has been commonly used to predict the general trend for fish landings with increased reliability and precision. In this paper, ARIMA models were applied to predict Lake Malombe annual fish landings and catch per unit effort (CPUE). The annual fish landings and CPUE trends were first observed and both were non-stationary. The first-order differencing was applied to transform the non-stationary data into stationary. Autocorrelation functions (AC), partial autocorrelation function (PAC), Akaike information criterion (AIC), Bayesian information criterion (BIC), square root of the mean square error (RMSE), the mean absolute error (MAE), percentage standard error of prediction (SEP), average relative variance (ARV), Gaussian maximum likelihood estimation (GMLE) algorithm, efficiency coefficient (E2), coefficient of determination (R2), and persistent index (PI) were estimated, which led to the identification and construction of ARIMA models, suitable in explaining the time series and forecasting. According to the measures of forecasting accuracy, the best forecasting models for fish landings and CPUE were ARIMA (0,1,1) and ARIMA (0,1,0). These models had the lowest values AIC, BIC, RMSE, MAE, SEP, ARV. The models further displayed the highest values of GMLE, PI, R2, and E2. The “auto. arima ()” command in R version 3.6.3 further displayed ARIMA (0,1,1) and ARIMA (0,1,0) as the best. The selected models satisfactorily forecasted the fish landings of 2725.243 metric tons and CPUE of 0.097 kg/h by 2024.

Assessing the Ergonomic Benefits of a New Adjustable Forklift Backrest

2020 ◽  
Vol 64 (1) ◽  
pp. 976-980
Author(s):  
Pranav Madhav Kuber ◽  
Ehsan Rashedi
Keyword(s):  
Comparative Study ◽  
Motion Capture ◽  
Center Of Pressure ◽  
Body Movement ◽  
Pressure Change ◽  
Motion Capture System ◽  
Design Features ◽  
Wide Range ◽  
Body Sizes ◽  
The Mean

A new forklift backrest has been developed by incorporating adjustability concepts into the design to facilitate comfort to a wide range of users. We have conducted a comparative study between the new and original backrests to assess the effectiveness of design features. Using the phenomenon of restlessness, discomfort of the user was associated with the amount of body movement, where we have used a motion- capture system and a force platform to quantify the individuals’ movement for a wide range of body sizes. Meanwhile, subjective comfort and design feedback were collected using a questionnaire. Our results showed a reduction in the mean torso movement and the maximum center of pressure change of location by 300 and 6 mm, respectively, for the new design. Taking advantage of adjustability feature, the new backrest design exhibited enhanced comfort for longer durations and reduced magnitude of discomfort for a wide range of participants’ body sizes.

Attractant for Vinegar Fly, Drosophila busckii, and Cluster Fly, Pollenia rudis (Diptera: Drosophilidae et Calliphoridae)

2009 ◽  
Vol 64 (3-4) ◽  
pp. 267-270 ◽  
Author(s):  
Vincas Būda ◽  
Sandra Radžiutė ◽  
Erikas Lutovinovas
Keyword(s):  
Field Test ◽  
Methyl Salicylate ◽  
Sticky Traps ◽  
First Report ◽  
Baited Traps ◽  
Vinegar Fly ◽  
The Mean ◽  
Dipteran Species ◽  
Drosophila Busckii

A field test carried out in an industrial greenhouse in Lithuania revealed the attractiveness of synthetic methyl salicylate (MeSa) to two dipteran species: the vinegar fl y, Drosophila busckii (Drosophilidae), and the cluster fl y, Pollenia rudis (Calliphoridae). The attractant for the former fl y species was especially effective, as sticky traps containing 0.25 ml of MeSa captured (814 ± 55) D. busckii flies/trap on average compared to (12 ± 4) flies/trap in control traps. The mean capture of P. rudis [(42 ± 4) flies/trap] was significantly higher in MeSa-baited traps compared to the control traps [(13 ± 4) flies/trap]. The presence of MeSa in emissions of many fruits suitable for D. busckii feeding allows to attribute this attractant to kairomones. In case of P. rudis, MeSa should be attributed to synomones (compounds beneficial for both receiver and sender), because adult flies feeding on flowers act as pollinators. This is the first report on the field-active attractant for D. busckii and the second for P. rudis.

scholarly journals Scavenging behaviour by Ergalatax contractus (Gastropoda: Muricidae) and interactions with Nassarius nodifer (Gastropoda: Nassariidae) in the Cape d'Aguilar Marine Reserve, Hong Kong

2006 ◽  
Vol 86 (1) ◽  
pp. 141-152 ◽  
Author(s):  
Brian Morton
Keyword(s):  
Hong Kong ◽  
Field Experiments ◽  
Marine Reserve ◽  
Flowing Water ◽  
Large Numbers ◽  
Baited Traps ◽  
Behavioural Characteristics ◽  
Shallow Subtidal ◽  
The Mean ◽  
Mean Time

Aspects of the feeding behaviour of Ergalatax contractus (Muricidae) were studied. Field experiments demonstrated that large numbers of individuals of this species, comprising ∼90% of a suite of gastropod scavengers, were attracted to baited traps in the subtidal sands of Lobster Bay, Cape d'Aguilar Marine Reserve, Hong Kong. Laboratory experiments identified the effective chemo-detection distances of E. contractus as 60 cm in still and >80 cm in flowing water, respectively. The average times to arrival at bait in still and flowing water were 92.3 and 69.0 min, respectively, but were significantly less for individuals experiencing a longer period of starvation. The mean time taken for E. contractus to consume a meal was 70.6 min.Comparisons were made between Ergalatax contractus and Nassarius nodifer, representative of a suite of sympatric scavenging nassariids in Lobster Bay. The nassariid arrived significantly faster at bait in both still (30.2 min) and flowing water (20.8 min) than E. contractus and fed faster (25.7 min), as is typical of representatives of the Nassariidae. Although the two species partition carrion resources temporally, manipulation experiments provided evidence for inter-specific competition between them. That is, although E. contractus possesses the morphological and behavioural characteristics of a predator, its opportunistic scavenging abilities have led to its success and numerical superiority on the shallow subtidal sands of Lobster Bay. The dominance of E. contractus in Lobster Bay, and elsewhere in Hong Kong, is unusual. Here, the normally predatory E. contractus, far outnumbers all other scavengers, possibly because of an enhanced, largely allochthonous, supply of food which it is able to exploit by virtue of its previously identified opportunistic habit of scavenging the leftovers of other predators. The presence of inter-specific competition between E. contractus and a sympatric suite of nassariids enhances, not impedes, carrion exploitation.

scholarly journals Embryonic exposure to conspecific chemicals suppresses cane toad growth and survival

2011 ◽  
Vol 8 (2) ◽  
pp. 226-229 ◽  
Author(s):  
Michael R. Crossland ◽  
Richard Shine
Keyword(s):  
Chemical Cues ◽  
Ecological Impacts ◽  
Cane Toad ◽  
Growth And Survival ◽  
Rhinella Marina ◽  
Embryonic Exposure ◽  
Body Sizes ◽  
Tropical Australia ◽  
Survival And Growth ◽  
Invasive Taxa

Adaptations to suppress the viability of conspecifics may provide novel ways to control invasive taxa. The spread of cane toads ( Rhinella marina ) through tropical Australia has had severe ecological impacts, stimulating a search for biocontrol. Our experiments show that cane toad tadpoles produce waterborne chemical cues that suppress the viability of conspecifics encountering those cues during embryonic development. Brief (72 h) exposure to these cues in the egg and post-hatching phases massively reduced rates of survival and growth of larvae. Body sizes at metamorphosis (about three weeks later) were almost twice as great in control larvae as in tadpole-exposed larvae. The waterborne cue responsible for these effects might provide a weapon to reduce toad recruitment within the species' invaded range.

Efficacy of antiaggregants for the pine engraver, Ipspini (Coleoptera: Scolytidae)

1994 ◽  
Vol 24 (12) ◽  
pp. 2469-2476 ◽  
Author(s):  
D.R. Devlin ◽  
J.H. Borden
Keyword(s):  
Untreated Control ◽  
Ground Surface ◽  
High Rate ◽  
High Dose ◽  
Dose Rates ◽  
Pine Engraver ◽  
Baited Traps ◽  
Initial Release ◽  
The Mean ◽  
Lodgepole Pines

The responses of pine engravers, Ipspini (Say), in British Columbia to ipsdienol-baited traps containing low, medium, and high dose rates of the antiaggregants verbenone and ipsenol, released from impregnated polyethylene and polypropylene beads, respectively, remained significantly lower than responses to ipsdienol-baited control traps throughout the spring. During the summer, the responses remained low only in traps containing medium and high dose rates of impregnated beads. Antiaggregant treatment densities of 100 and 400 bubble cap release points per hectare reduced the numbers of pine engravers caught in ipsdienol-baited, multiple-funnel traps by 66.1 and 76.8%, respectively. In 50 × 50 m thinning-simulation plots treated with a broadcast distribution of antiaggregant-impregnated beads in 1990, 32.9% of the felled lodgepole pines, Pinuscontorta Dougl., were attacked; in untreated control plots, 53.1% were attacked. The mean attack density per square metre of available bark surface in the treated plots (1.3) was significantly lower than that in the untreated plots (1.9); however, where attack occurred there was no difference (8.8 and 9.4 attacks/m2, respectively). In a 1991 experiment, verbenone- and ipsenol-impregnated beads were applied to 15 × 15 m thinning-simulation plots at initial release rates of 2.5 mg of verbenone and 0.05 mg of ipsenol per square metre of ground surface per day, and at double these rates. For three treatments, low and high rates 3 weeks prior to the first attack by I. pini and a high rate 2 weeks prior to attack, the mean attacks per square metre of available bark surface per week were reduced by 77.1, 82.9, and 97.1%, respectively, compared with attacks on felled pines in untreated control plots. The results of these experiments suggest that a timely application of broadcast antiaggregants would prevent the development of an outbreak population of I. pini.

scholarly journals Divergent temperature-specific metabolic and feeding rates of native and invasive crayfish

2021 ◽  
Author(s):  
T. J. Ruokonen ◽  
J. Karjalainen
Keyword(s):  
Native Species ◽  
Ecological Impacts ◽  
Metabolic Rates ◽  
Feeding Rates ◽  
Cold Temperatures ◽  
Signal Crayfish ◽  
Climatic Scenarios ◽  
Invasive Crayfish ◽  
Noble Crayfish ◽  
The Impact

AbstractTemperature is one of the most important factors governing the activity of ectothermic species, and it plays an important but less studied role in the manifestation of invasive species impacts. In this study, we investigated temperature-specific feeding and metabolic rates of invasive and native crayfish, and evaluated how temperature regulates their ecological impacts at present and in future according to different climatic scenarios by bioenergetics modelling. We conducted a series of maximum food consumption experiments and measured the metabolic rates of cold-adapted native noble crayfish (Astacus astacus) and invasive signal crayfish (Pacifastacus leniusculus) originally from a warmer environment over a temperature gradient resembling natural temperatures in Finland. The maximum feeding rates and routine metabolic rates (RMR) of native noble crayfish were significantly higher at low temperatures (< 10 °C than the rates of invasive signal crayfish. The RMRs of the species crossed at 18 °C, and the RMRs of signal crayfish were higher at temperatures above 18 °C. These findings indicate that the invader’s thermal niche has remained stable, and the potential impacts per capita are lower at suboptimal cold temperatures than for the native species. Our bioenergetics modelling showed that the direct annual predation impact of noble and signal crayfish seem similar, although the seasonal dynamics of the predation differs considerably between species. Our results highlight that the temperature-specific metabolic and feeding rates of species need to be taken into account in the impact assessment instead of simple generalisations of the direction or magnitude of impacts.

scholarly journals Force and Boldness: Cumulative Assets of a Successful Crayfish Invader

2021 ◽  
Vol 9 ◽  
Author(s):  
Lucian Pârvulescu ◽  
Dan Ioan Stoia ◽  
Kristian Miok ◽  
Mihaela Constanţa Ion ◽  
Adela Estera Puha ◽  
...  
Keyword(s):  
Native Species ◽  
Trophic Position ◽  
Invasion Success ◽  
Muscular Tissue ◽  
Agonistic Interactions ◽  
Muscle Energetics ◽  
Reproduction Strategies ◽  
Invasive Crayfish ◽  
Natural Equilibrium ◽  
Native Crayfish

Multiple causes can determine the disturbance of natural equilibrium in a population of a species, with a common one being the presence of invasive competitors. Invasives can drive native species to the resettlement of the trophic position, changing reproduction strategies or even daily normal behaviours. Here, we investigated the hypothesis that more effective anatomical features of an intruder (Faxonius limosus) come with increased boldness behaviour, contributing to their invasion success in competition against the native species (Pontastacus leptodactylus). We tested the boldness of specimens representing the two species by video-based assessment of crayfish individuals’ attempts to leave their settlement microenvironment. The experiment was followed by a series of measurements concerning chelae biometry, force and muscle energetics. The native species was less expressive in terms of boldness even if it had larger chelae and better muscular tissue performance. In contrast, because of better biomechanical construction of the chelae, the invasive species was capable of twice superior force achievements, which expectedly explained its bolder behaviour. These findings suggest that, in interspecific agonistic interactions, the behaviour strategy of the invasive crayfish species is based on sheer physical superiority, whereas the native crayfish relies on intimidation display.

scholarly journals Can Mating Disruption Be a Possible Route to Control Plum Fruit Moth in Mediterranean Environments?

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 589
Author(s):  
Gabriella Lo Verde ◽  
Salvatore Guarino ◽  
Stefano Barone ◽  
Roberto Rizzo
Keyword(s):  
Mating Disruption ◽  
Solid Phase ◽  
Economic Damage ◽  
Infestation Level ◽  
Essential Factor ◽  
Field Exposure ◽  
Pheromone Emission ◽  
Baited Traps ◽  
The Mean ◽  
Number Of Males

Control of the plum fruit moth, Grapholita funebrana Treitschke (Lepidoptera: Tortricidae), has been mainly based on the use of chemical insecticides, which can cause undesirable side effects, leading to a growing interest towards alternative sustainable strategies. The aim of this study was to evaluate the effect of the mating disruption technique on G. funebrana infestation in plum orchards, by comparing the number of male captures in pheromone-baited traps, and evaluating the damage to fruits in plots treated with the pheromone dispersers and in control plots. The study was carried out in 2012 and 2014 in three organic plum orchards, on the cultivars Angeleno, Friar, President and Stanley. To evaluate the pheromone emission curve of the dispensers from the openings to the end of the trials, a chemical analysis was carried out by solid phase micro-extraction followed by gas chromatography, followed by mass spectrometry. In all years and orchards the mean number of males caught in traps placed in the treatment plots was always significantly lower than untreated plots. Pheromone emission from the dispensers was highest at the opening, and was still considerable at 54 days of field exposure, while it significantly decreased after 72 days of field exposure. Cultivar was confirmed to be an essential factor in determining the fruit infestation level. Pheromone treatment significantly reduced fruit infestation, but not economic damage.

Sign in / Sign up

Export Citation Format

Share Document