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 Not easy to catch: multiple covariates influence catch rates of brown shrimp (Crangon crangon L.), potentially affecting inferences drawn from catch and landings data

2018 ◽  
Vol 75 (4) ◽  
pp. 1318-1328 ◽  
Author(s):  
Katharina Friederike Schulte ◽  
Andreas Dänhardt ◽  
Marc Hufnagl ◽  
Volker Siegel ◽  
Werner Wosniok ◽  
...  
Keyword(s):  
North Sea ◽  
Stock Assessment ◽  
Brown Shrimp ◽  
Catch Per Unit Effort ◽  
Crangon Crangon ◽  
Reproductive State ◽  
Factors Affecting ◽  
Southern North Sea ◽  
Unit Effort ◽  
Catch Rates

Abstract Brown shrimps (Crangon crangon) occur in high densities in the southern North Sea and support a large, but so far unmanaged fishery with >500 vessels. Cohort-based stock assessment is not possible, and catch per unit effort from scientific surveys and commercial landings are the only variables collected. Landings per unit effort are currently used to approximate the state of stock and to trigger catch restrictions, but, although decisive in interpreting unit catches or landings, factors affecting catch rates are rarely understood. Using data from two long-term (1997–2010) scientific surveys conducted in autumn and winter, respectively, in the southern North Sea and from a vertically resolving stow net deployed at two stations in the German Wadden Sea (2005–2007), we investigate the effects of season, reproductive state, size, tidal state, daylight, and water depth on catch rates of brown shrimp. Log-linear random intercept models revealed an influence of all factors examined on the catch rate. Depth had a clear effect on the composition of size and reproductive state, supporting the hypothesis that brown shrimp utilize selective tidal stream transport to migrate to depths preferred during certain periods within their life cycle. The vertical distribution of brown shrimp across the water column revealed that on average two thirds to three quarters of the brown shrimps were located above reach of the standard shrimp catching gear. Our findings indicate that multiple factors and interactions affect catch rates of brown shrimp and, thus, need to be accounted for when interpreting unit catches or landings for management purposes. We suggest that brown shrimps are not primarily demersal, and that stock size estimates solely relying on beam trawl data may underestimate the true density of shrimps per area.

scholarly journals Is the clouded leopard Neofelis nebulosa extinct in Taiwan, and could it be reintroduced? An assessment of prey and habitat

Oryx ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 261-269 ◽  
Author(s):  
Po-Jen Chiang ◽  
Kurtis Jai-Chyi Pei ◽  
Michael R. Vaughan ◽  
Ching-Feng Li ◽  
Mei-Ting Chen ◽  
...  
Keyword(s):  
Habitat Restoration ◽  
Prey Species ◽  
Distribution Patterns ◽  
Camera Trap ◽  
Suitable Habitat ◽  
Altitudinal Distribution ◽  
Clouded Leopard ◽  
Prey Biomass ◽  
Neofelis Nebulosa ◽  
Human Encroachment

AbstractDuring 1997–2012 we conducted a nationwide camera-trapping survey and assessed the availability of prey and habitat for the clouded leopard Neofelis nebulosa in Taiwan. We surveyed 1,249 camera-trap sites over 113,636 camera-trap days, from the seashore to an altitude of 3,796 m and covering various types of vegetation. No clouded leopards were photographed during 128,394 camera-trap days, including at 209 sites in other studies, confirming the presumed extinction of clouded leopards in Taiwan. Assessment of the prey base revealed altitudinal distribution patterns of prey species and prey biomass. Areas at lower altitudes and with less human encroachment and hunting supported a higher prey biomass and more of the typical prey species of clouded leopards. Habitat analysis revealed 8,523 km2 of suitable habitat but this was reduced to 6,734 km2 when adjacent areas of human encroachment were subtracted. In the absence of hunting and large mammalian carnivores the major prey of clouded leopards in Taiwan, such as Formosan macaques Macaca cyclopis, Reeves's muntjacs Muntiacus reevesi, Formosan serow Capricornis swinhoei and sambar Rusa unicolor, could become over-abundant. Thus, it is important to address the cascading effect of the disappearance of top-down predator control. Our assessment indicated that, with proper regulation of hunting, habitat restoration and corridor improvement, it may be possible to reintroduce the clouded leopard.

scholarly journals Catch per Unit Effort Dynamic of Yellowfin Tuna Related to Sea Surface Temperature and Chlorophyll in Southern Indonesia

Fishes ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 28
Author(s):  
Budy Wiryawan ◽  
Neil Loneragan ◽  
Ulfah Mardhiah ◽  
Sonja Kleinertz ◽  
Prihatin Ika Wahyuningrum ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Yellowfin Tuna ◽  
Additive Models ◽  
Sea Surface ◽  
Catch Per Unit Effort ◽  
Unit Effort ◽  
The Government ◽  
Tuna Fisheries

Tuna fisheries are the most valuable fisheries in the world, with an estimated market value of at least US$42 billion in 2018. Indonesia plays an important role in the global tuna fisheries and has committed to improve its fisheries management; therefore, a pilot of long-term spatial-temporal data bases was developed in 2012, however none have utilized data to have better understanding for management improvement. In this study, the annual and seasonal variation of large (≥10 kg) Yellowfin Tuna (YFT) catch per unit effort (CPUE) have been investigated and the influence of sea surface temperature (SST) and chlorophyll-a on these variables examined. We used fish landing data from West Nusa Tenggara recorded every month between 2012 and 2017 and analyzed using generalized linear models and generalized additive models. We found a seasonal and annual pattern of tuna abundance affected by SST and chlorophyll-a (chl a) and related to upwelling and El Nino event. These results also suggest that a two-month closure to fishing in August and September in southern Lombok is worth considering by the Government to maximize conservation of stocks due to a high abundance of juveniles emerging during the upwelling months from June to August.

scholarly journals Interpreting catch per unit effort data to assess the status of individual stocks and communities

2006 ◽  
Vol 63 (8) ◽  
pp. 1373-1385 ◽  
Author(s):  
Mark N. Maunder ◽  
John R. Sibert ◽  
Alain Fonteneau ◽  
John Hampton ◽  
Pierre Kleiber ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Stock Assessment ◽  
Limited Information ◽  
Catch Per Unit Effort ◽  
Fish Stocks ◽  
Unit Effort ◽  
Strategy Evaluation ◽  
The Status ◽  
Catch Rates ◽  
Management Advice

AbstractDespite being one of the most common pieces of information used in assessing the status of fish stocks, relative abundance indices based on catch per unit effort (cpue) data are notoriously problematic. Raw cpue is seldom proportional to abundance over a whole exploitation history and an entire geographic range, because numerous factors affect catch rates. One of the most commonly applied fisheries analyses is standardization of cpue data to remove the effect of factors that bias cpue as an index of abundance. Even if cpue is standardized appropriately, the resulting index of relative abundance, in isolation, provides limited information for management advice or about the effect of fishing. In addition, cpue data generally cannot provide information needed to assess and manage communities or ecosystems. We discuss some of the problems associated with the use of cpue data and some methods to assess and provide management advice about fish populations that can help overcome these problems, including integrated stock assessment models, management strategy evaluation, and adaptive management. We also discuss the inappropriateness of using cpue data to evaluate the status of communities. We use tuna stocks in the Pacific Ocean as examples.

scholarly journals Population dynamics and CPUE of Alosa genus with emphasis on Alosa braschnikovi (Borodin, 1904) on the coasts of Golestan Province, Iran

2018 ◽  
Vol 19 (1) ◽  
pp. 59-66
Author(s):  
ZOBEYDE BIBAK ◽  
SEYYED YOUSEF PAIGHAMBARI ◽  
MOJTABA POULADI ◽  
RASOUL GHORBANI ◽  
SEYYED ABBAS HOSSEINI ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Sex Ratio ◽  
Relative Abundance ◽  
Fish Species ◽  
Age Groups ◽  
Abundant Species ◽  
Catch Per Unit Effort ◽  
Beach Seine ◽  
Unit Effort ◽  
Golestan Province

Bibak Z, Paighambari SY, Pouladi M, Ghorbani R, Hosseini SA, Yahyaei M. 2018. Population dynamics and CPUE of Alosa genus with emphasis on Alosa braschnikovi (Borodin, 1904) on the coasts of Golestan Province, Iran. Biodiversitas 19: 59-66. The aim of this study was to compare relative abundance and catch per unit effort of members of the Alosa genus (family: Clupeidae) in the fishing grounds of Gomishan and Miankale in Golestan coasts. Sampling operations were done by beach seine during 2011 to 2012. A total of 240 fish were collected. Identified species in Gomishan were: Alosa braschnikovi (Borodin, 1904) and A. saposchnikovi (Grimm, 1887). The most abundant species in this region were individuals of A. braschnikovi. The highest length and weight in the region were 35.6±1.85 mm and 447.8±57.43 gr for Alosa braschnikovi in Gomishan. Besides the two mentioned species, A. kessleri (Grimm, 1887) was caught in Miankale coasts. The most abundant species again was Alosa braschnikovi in this region. The highest length and weight were 33.12±3.18 cm and 362.5±99.57 gr for Alosa braschnikovi in Miankale region. The results showed that mean of CPUE in Miankale was higher than in the Gomishan region. The comparison of sex ratio for shads showed that males were dominant against females. Also, the comparison between species showed that the highest values for length, and weight of fish species compared belonged to Alosa braschnikovi. Among the Alosa braschnikovi fishes caught, individuals were in the range of 2 to 5 age groups within the two compared regions and most abundant were observed in 4 age groups.

scholarly journals THE DISTRIBUTION OF ARIID CATFISH (ARIIDAE) IN THE HAU RIVER ESTUARY

2020 ◽  
Vol 1 (38) ◽  
pp. 67-74
Author(s):  
Hoang Thi My To ◽  
Dung Tri Duong ◽  
Dinh Dac Tran
Keyword(s):  
Relative Abundance ◽  
River Estuary ◽  
Mekong Delta ◽  
Primary Factor ◽  
Catch Per Unit Effort ◽  
Unit Effort

From July 2017 to June 2019 at Hau estuary in the Mekong Delta, Vietnam, Ariid catfish were surveyed from theHau River estuary (Tran De and Dinh An) to Cai Cui area. Fishing yield was calculated based on CPUE (catch per unit effort). Five species of Ariid catfish were recorded (Arius maculatus, Osteogeneiosus militaris, Ariusvenosus, Nemapteryx nenga and Cephalocassis borneensis). The relative abundance of Ariid catfish was substantial and reached the highest in Tran De (CPUEw = 934.45 g/ha) followed by Dinh An estuary (CPUE =931.68 g/ha) and Tran De estuary (CPUE = 904.71 g/ha); Fishing yield in Cai Cui was the lowest with a CPUE of 36.48 g/ha. In addition, the highest distribution found was Arius maculatus (63.35%) and was followed by Osteogeneiosus militaris (32.94%). However, the biodiversity of Arridae was not a reflection of relative abundance with the Tran De estuary having the highest result H’ = 0.83, followed by Tran De (H’ = 0.76)and lowest was in Dai Ngai (H’ = 0,10). These results indicate that salinity can be considered a primary factor influencing the distribution of Ariid catfish in Hau River estuary.

Internet-based Online Higher Education in Nepal Amidst COVID-19

2020 ◽  
Author(s):  
Ashis Acharya ◽  
Nabaraj Poudyal ◽  
Ganesh Lamichhane ◽  
Babita Aryal ◽  
Bibek Raj Bhattarai ◽  
...  
Keyword(s):  
Higher Education ◽  
Human Life ◽  
The Internet ◽  
Online Classes ◽  
Traditional Concept ◽  
Digital Platforms ◽  
Factors Affecting ◽  
Online Higher Education ◽  
Alternative Means ◽  
The Government

The COVID-19 global pandemic has affected all aspects of human life, with education, not an exception. In an attempt to stop the SARS-CoV-2 spreading like wildfire, the Government of Nepal has implemented nationwide lockdowns since March 24, 2020, that have enforced schools and universities to shut down. As a consequence, more than four hundred thousand students of various levels in higher education institutions (HEIs) are in a dilemma about restoring the situation. Several HEIs, nationwide, have leaped forward from the traditional concept of learning—limited within the boundary of the classroom—to choosing digital platforms as an alternative means of teaching because of the pandemic. For this research, the descriptive and inferential analysis was carried out to investigate the effects and challenges of learning via digital platforms during this pandemic. Data were collected from students and faculty at various levels of higher education and analyzed statistically with different factors using t-test and ANOVA, and variables were found to be approximately normally distributed. The study revealed that 70% of the respondents had access to the Internet, but 36% of the Internet accessed did not continue online classes due to unexpected disturbance in Internet and electrical connectivity. Likewise, 65% of students did not feel comfortable with online classes, and among attendees of online classes, 78% of students want to meet the instructor for a better understanding of course matters. According to the analytic hierarchy process (AHP) model, three factors, such as institutional policy, internet access, and poverty, are found to be significant factors affecting the online higher education systems in Nepal. On the brighter side, this outbreak has brought ample opportunities to reform the conventional teaching-learning paradigm in Nepal.

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
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