scholarly journals Catch-per-unit-effort and size spectra of lake fish assemblages reflect underlying patterns in ecological conditions and anthropogenic activities across regional and local scales

2016 ◽  
Vol 73 (4) ◽  
pp. 535-546 ◽  
Author(s):  
Cindy Chu ◽  
Nigel P. Lester ◽  
Henrique C. Giacomini ◽  
Brian J. Shuter ◽  
Donald A. Jackson
Keyword(s):  
Body Size ◽  
Fish Assemblages ◽  
Anthropogenic Activities ◽  
Ecological Indicators ◽  
Size Spectrum ◽  
Catch Per Unit Effort ◽  
Ecological Processes ◽  
Boosted Regression Tree ◽  
Unit Effort ◽  
Lake Fish

Across broad geographic scales, ecological indicators for fish assemblages should represent causal ecological processes, be sensitive enough to show patterns across the landscape, and reflect underlying biotic or abiotic conditions that influence those patterns. We assessed the responses of commonly applied ecological indicators for lake fish assemblages (mean body size, catch-per-unit-effort (CPUE), and normalized length size spectrum (NLSS) slope) to regional (climate, water chemistry, and watershed stress due to human activities) and local (lake morphometry, water quality, and angling pressure) ecological and anthropogenic variables. The indicators were estimated using fish assemblage catch data acquired via a standardized gillnetting protocol implemented within 693 lakes in Ontario, Canada. To our knowledge, our study is the first size-based or catch-based indicator evaluation to include detailed observations of angling pressure on hundreds of inland lakes. Boosted regression tree models showed that CPUE of large-bodied organisms and NLSS slope best described underlying patterns in the regional and local variables. Models developed with a mix of regional and local variables performed better than models developed with regional or local variables alone. The relative influences of the variables and responses varied among indicators, but in general, ecological variables had greater influence on the indicators than anthropogenic variables. These results emphasize the complex and multiscaled nature of factors and ecological processes affecting body size, habitat-community production, and trophic dynamics in lake fish assemblages.

scholarly journals Geographical patterns in the body-size structure of European lake fish assemblages along abiotic and biotic gradients

2014 ◽  
Vol 41 (12) ◽  
pp. 2221-2233 ◽  
Author(s):  
Matthias Emmrich ◽  
Stéphanie Pédron ◽  
Sandra Brucet ◽  
Ian J. Winfield ◽  
Erik Jeppesen ◽  
...  
Keyword(s):  
Body Size ◽  
Fish Assemblages ◽  
Size Structure ◽  
The Body ◽  
Geographical Patterns ◽  
Lake Fish

Estimating whole-lake fish catch per unit effort

2015 ◽  
Vol 172 ◽  
pp. 287-302 ◽  
Author(s):  
T.J. Alexander ◽  
P. Vonlanthen ◽  
G. Periat ◽  
F. Degiorgi ◽  
J.C. Raymond ◽  
...  
Keyword(s):  
Catch Per Unit Effort ◽  
Unit Effort ◽  
Fish Catch ◽  
Lake Fish

scholarly journals Influence of protected areas on fish assemblages and fisheries in a large tropical river

Oryx ◽  
2016 ◽  
Vol 51 (2) ◽  
pp. 268-279 ◽  
Author(s):  
Friedrich Wolfgang Keppeler ◽  
Gustavo Hallwass ◽  
Renato Azevedo Matias Silvano
Keyword(s):  
Protected Areas ◽  
Fish Assemblage ◽  
Environmental Heterogeneity ◽  
Fish Assemblages ◽  
Sustainable Use ◽  
Environmental Parameters ◽  
Freshwater Ecosystems ◽  
Catch Per Unit Effort ◽  
Unit Effort ◽  
Positive Effect

AbstractProtected areas are one of the main tools for biological conservation worldwide. Although they have contributed to an increase in fish abundance and alleviated the impacts of fishing on marine ecosystems, the impacts of fishing and of protected areas in freshwater ecosystems are less well known. We compared fishing productivity and fish assemblage descriptors of two distinct protected areas designated for sustainable use of natural resources and an unprotected area in the Tapajós River, in the Brazilian Amazon. Two hypotheses were tested: (1) fishers from protected areas have higher catch per unit effort than those from unprotected areas; and (2) fish assemblages in protected areas have higher biomass, abundance, presence of target species, species richness, fish size and mean trophic level than those in unprotected areas. A total of 2,013 fish landings were recorded and two surveys were undertaken to sample fishes. Eleven environmental parameters were quantified to distinguish between effects of environmental heterogeneity and protected areas. The catch per unit effort of fishers was higher within protected areas than in unprotected areas, suggesting that protected areas reduce the levels of fishing pressure and increase fishing productivity. However, the fish assemblage descriptors were correlated more with environmental variables than with protected areas, indicating a relatively weak effect of protected areas on fish communities in lakes. The results highlight the importance of considering the influence of environmental heterogeneity in fish conservation programmes, and the positive effect of protected areas on fishing productivity in freshwater environments.

Qarun Lake fisheries; Fishing gears, Species composition and Catch per unit effort

2014 ◽  
Vol 18 (2) ◽  
pp. 39-49
Author(s):  
Sabry El-Serafy ◽  
Alaa El-Haweet ◽  
Azza El-Ganiny ◽  
Alaa El-Far
Keyword(s):  
Species Composition ◽  
Catch Per Unit Effort ◽  
Unit Effort ◽  
Fishing Gears ◽  
Lake Fisheries

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.

Environmental drivers of golden tilefish ( Lopholatilus chamaeleonticeps ) commercial landings and catch‐per‐unit‐effort

2021 ◽  
Author(s):  
Geneviève Nesslage ◽  
Vyacheslav Lyubchich ◽  
Paul Nitschke ◽  
Erik Williams ◽  
Churchill Grimes ◽  
...  
Keyword(s):  
Environmental Drivers ◽  
Catch Per Unit Effort ◽  
Unit Effort

Ecological and environmental factors affecting the foraging activity of the White-bellied Heron Ardea insignis (Hume, 1878) in Bhutan

2021 ◽  
pp. 1-18
Author(s):  
PEMA KHANDU ◽  
GEORGE A. GALE ◽  
SARA BUMRUNGSRI
Keyword(s):  
Relative Abundance ◽  
Habitat Restoration ◽  
Prey Species ◽  
Catch Per Unit Effort ◽  
Factors Affecting ◽  
Prey Biomass ◽  
Gravel Mining ◽  
Unit Effort ◽  
Prey Preferences ◽  
The Government

Summary White-bellied Heron Ardea insignis (WBH) is critically endangered, but we lack data on many aspects of its basic ecology and threats to the species are not clearly understood. The goal of this study was to analyse WBH foraging microhabitat selection, foraging behaviour, and prey preferences in two river basins (Punatsangchhu and Mangdechhu) in Bhutan which are likely home to one of the largest remaining populations of WBH. We also explored the relationship between the relative abundance of the WBH and prey biomass catch per unit effort within four foraging river microhabitats (pool, pond, riffle and run). Prey species were sampled in 13 different 100-m thalweg lengths of the rivers using cast nets and electrofishing gear. Riffles and pools were the most commonly used microhabitats; relative abundance was the highest in riffles. The relative abundance of WBH and prey biomass catch per unit effort (CPUE) also showed a weak but significant positive correlation (rs = 0.22). The highest biomass CPUE was observed in riffles while the lowest was found in the ponds. From the 97 prey items caught by the WBH, 95% of the prey were fish. The WBH mainly exploited three genera of fish (Garra, Salmo, and Schizothorax) of which Schizothorax (64%) was the most frequently consumed. This study provides evidence in support of further protection of critical riverine habitat and fish resources for this heron. Regular monitoring of sand and gravel mining, curbing illegal fishing, habitat restoration/mitigation, and developing sustainable alternatives for local people should be urgently implemented by the government and other relevant agencies. Further study is also required for understanding the seasonal variation and abundance of its prey species in their prime habitats along the Punatsangchhu and Mangdechhu basins.

scholarly journals Insights on the Impacts of Hydroclimatic Extremes and Anthropogenic Activities on Sediment Yield of a River Basin

Earth ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 32-50
Author(s):  
Rocky Talchabhadel ◽  
Jeeban Panthi ◽  
Sanjib Sharma ◽  
Ganesh R. Ghimire ◽  
Rupesh Baniya ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
River Basin ◽  
Extreme Precipitation ◽  
Suspended Sediment Concentration ◽  
Anthropogenic Activities ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Mountain River ◽  
Ecological Processes ◽  
Precipitation Indices

Streamflow and sediment flux variations in a mountain river basin directly affect the downstream biodiversity and ecological processes. Precipitation is expected to be one of the main drivers of these variations in the Himalayas. However, such relations have not been explored for the mountain river basin, Nepal. This paper explores the variation in streamflow and sediment flux from 2006 to 2019 in central Nepal’s Kali Gandaki River basin and correlates them to precipitation indices computed from 77 stations across the basin. Nine precipitation indices and four other ratio-based indices are used for comparison. Percentage contributions of maximum 1-day, consecutive 3-day, 5-day and 7-day precipitation to the annual precipitation provide information on the severity of precipitation extremeness. We found that maximum suspended sediment concentration had a significant positive correlation with the maximum consecutive 3-day precipitation. In contrast, average suspended sediment concentration had significant positive correlations with all ratio-based precipitation indices. The existing sediment erosion trend, driven by the amount, intensity, and frequency of extreme precipitation, demands urgency in sediment source management on the Nepal Himalaya’s mountain slopes. The increment in extreme sediment transports partially resulted from anthropogenic interventions, especially landslides triggered by poorly-constructed roads, and the changing nature of extreme precipitation driven by climate variability.

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