scholarly journals Estimating total mortality and asymptotic length of Crangon crangon between 1955 and 2006

2010 ◽  
Vol 67 (5) ◽  
pp. 875-884 ◽  
Author(s):  
Marc Hufnagl ◽  
Axel Temming ◽  
Volker Siegel ◽  
Ingrid Tulp ◽  
Loes Bolle
Keyword(s):  
Total Mortality ◽  
Demersal Fish ◽  
Crangon Crangon ◽  
Length Frequency ◽  
Growth Constant ◽  
Mean Values ◽  
Frequency Distributions ◽  
The 1960S ◽  
Mortality Estimates

Abstract Hufnagl, M., Temming, A., Siegel, V., Tulp, I., and Bolle, L. 2010. Estimating total mortality and asymptotic length of Crangon crangon between 1955 and 2006. – ICES Journal of Marine Science, 67: 875–884. Total mortality (Z, year−1) of southern North Sea brown shrimp (Crangon crangon) was determined as Z = θK, based on the von Bertalanffy length–growth constant (K, year−1) and θ derived from length-based methods. Mortality estimates were based on length frequency distributions obtained from four long-term dataseries (1955–2006): German Demersal Young Fish Survey, Dutch Demersal Fish Survey, and two German Bycatch series (Büsum and East Frisia). Four methods to estimate θ and L∞ were evaluated. Highest total mortality (Z = 8 year−1) was estimated for the early 1990s, and the lowest (Z = 4 year−1) for the 1960s. Accounting for these differences, a median Z rather than mean values was calculated for the whole series, and the value ranged from 5.74 (Ssentongo and Larkin method), through 5.65 (Beverton and Holt method) and 5.64 (Jones and Zalinge method), to 5.35 (length-converted catch curves). Over the whole period, an increase in θ and a decrease in the proportion of shrimps >60 mm in the catch was observed, whereas asymptotic length L∞ remained constant (at 79.3 mm total length).

Length-weight relationship, growth and mortality ofAnadara granosain Penang Island, Malaysia: an approach using length-frequency data sets

2014 ◽  
Vol 95 (2) ◽  
pp. 381-390 ◽  
Author(s):  
Mohammad Reza Mirzaei ◽  
Zulfigar Yasin ◽  
Aileen Tan Shau Hwai
Keyword(s):  
Growth Parameters ◽  
Total Mortality ◽  
Growth Function ◽  
Data Sets ◽  
Frequency Data ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Weight Relationship ◽  
Logarithmic Relationship ◽  
Length Frequency Data

Length-weight relationship, growth parameters and mortality rates ofAnadara granosain the intertidal zone of Balik Pulau, Penang Island, West Coast of Malaysia were investigated based on monthly length-frequency data (December 2011 to November 2012). A total of 548 individuals ranging from 11.25 to 33.13 mm size were subjected to analysis. Logarithmic relationship between the length and weight was LogW = 2.328LogL − 2.537 (R2 = 0.922) for combined sexes. From this equation it was clear that the exponent ‘b’ value forA. granosashowed a negative allometric growth (b < 3). A von Bertalanffy growth function with an asymptotic length (L∞) of 35.40 mm and a growth constant (K) of 1.1 year−1was established from length frequency distributions. Thet0(−0.140) was estimated by substituting theL∞andKin the Pauly's equation. The sizes attained byA. granosawere 10.13, 14.36, 17.89, 20.82, 23.56 and 25.29 mm at the end of 2, 4, 6, 8, 10 and 12 months, respectively. The estimated growth performance index (Ø) was 3.13 while the estimated lifespan of the cockles was about 2.72 years at the study area. The estimated value of total mortality based on length-converted catch curve wasZ = 3.02 year−1. The natural mortality (M) and fishing mortality (F) rates were 1.84 and 0.48 year−1, respectively. The exploitation level (E) ofA. granosawas 0.20, which indicated slight fishing pressure on the stock.

scholarly journals Properties of age compositions and mortality estimates derived from cohort slicing of length data

2014 ◽  
Vol 72 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Lisa E. Ailloud ◽  
Matthew W. Smith ◽  
Amy Y. Then ◽  
Kristen L. Omori ◽  
Gina M. Ralph ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Age Groups ◽  
Total Mortality ◽  
Frequency Distributions ◽  
Accuracy And Precision ◽  
High K ◽  
Length Data ◽  
High Age ◽  
Low K ◽  
Mortality Estimates

Abstract Cohort slicing can be used to obtain catch-at-age data from length frequency distributions when directly measured age data are unavailable. The procedure systematically underestimates the relative abundance of the youngest age groups and overestimates abundance at older ages. Cohort-sliced catch-at-age data can be used to estimate total mortality rate (Z) using a regression estimator or the Chapman–Robson estimator for right truncated data. However, the effect of cohort slicing on accuracy and precision of resulting Z estimates remains to be determined. We used Monte Carlo simulation to estimate the per cent bias and per cent root mean square error of the unweighted regression, weighted regression, and Chapman–Robson mortality estimators applied to cohort-sliced data. Incompletely recruited age groups were truncated from the cohort-sliced catch-at-age data using previously established recommendations and a variety of plus groups was used to combine older age groups. The sensitivity of the results to a range of plausible biological combinations of Z, growth parameters, recruitment variability, and length-at-age error was tested. Our simulation shows that cohort slicing can work well in some cases and poorly in others. Overall, plus group selection was more important in high K scenarios than it was in low K scenarios. Surprisingly, defining the plus group to start at a high age worked well in some cases, although length and age are poorly correlated for old ages. No one estimator was uniformly superior; we therefore provide recommendations concerning the appropriate estimator and plus group to use, depending on the parameters characterizing the stock. We further recommend that simulations be performed to determine exactly which plus group would be most appropriate given the scenario at hand.

scholarly journals ASPEK BIOLOGI IKAN LAYUR (Lepturacanthus savala Cuvier, 1829) DI PERAIRAN PANGANDARAN, JAWA BARAT

2017 ◽  
Vol 9 (2) ◽  
pp. 133
Author(s):  
Puput Fitri Rachmawati ◽  
Sri Turni Hartati
Keyword(s):  
Mortality Rate ◽  
Average Length ◽  
Total Mortality ◽  
Demersal Fish ◽  
Parameter Analysis ◽  
Assessment Tools ◽  
Population Parameter ◽  
Fish Production ◽  
Length Frequency ◽  
Lepturacanthus Savala

Sumberdaya ikan demersal di perairan Pangandaran mendominasi hasil tangkapan sebesar 32,90 % dari total produksi ikan secara keseluruhan, pada tahun 2015 jenis ikan layur (Lepturacanthus savala) berkontribusi sebanyak 47,31 % dari total produksi ikan demersal, merupakan salah satu jenis ikan demersal yang bernilai ekonomis tinggi. Penelitian ini bertujuan untuk mengetahui aspek biologi dan parameter populasi L. savala di perairan Pangandaran. Penelitian dilakukan pada bulan Juni – Desember 2015, data yang terkumpul meliputi panjang dan berat ikan, jenis kelamin, tingkat kematangan gonad, berat gonad, serta data statistik perikanan. Analisis parameter populasi didasarkan pada data length-frequency panjang dan dilakukan dengan bantuan program FiSAT II (FAO-ICLARM Stock Assesment Tools II). Hasil menunjukkan hubungan panjang-berat bersifat alometrik negatif dengan nilai b = 2,92; nisbah kelamin jantan terhadap betina 1,0:3,2. Panjang rata-rata ikan tertangkap lebih besar dari panjang pertama kali matang gonad (L50% = 57,19 cmTL > Lm = 47,23 cmTL). Panjang asimtotik (L) sebesar 111,00 cmTL, laju pertumbuhan (K) sebesar 0,56/tahun. Selanjutnya laju kematian total (Z) sebesar 3,46/tahun, laju kematian alami (M) sebesar 0,85/tahun, dan laju kematian akibat penangkapan (F) sebesar 2,61/tahun; sehingga laju eksploitasi (E) sebesar 0,75, terindikasi kondisi fully exploited. Jika dibiarkan kondisi tersebut dapat mengarah pada recruitment overfishing. Untuk menjaga keberlangsungan kelestarian sumberdaya L. savala, pengelolaan dapat dilakukan dengan cara membatasi intensitas penangkapan, memperbesar ukuran mata jaring, dan penetapan kawasan reservat terhadap sejumlah stok induk yang memadai. The fish production in the Pangandaran waters dominated demersal fish resources by 32.90% of total landed in 2015. Savalai hairtail contributes 47,31% to total demersal fish production. This study aims to determine the biological aspects and population parameters of Lepturacanthus savala in Pangandaran waters. Data collection conducted in June - December 2015, with data collected including length and weight, sex, the maturity level of gonads, gonad weight, and fishery statistics data. Population parameter analysis based on length-frequency data was done by using FAO-ICLARM Stock Assessment Tools II (FiSAT II) program. The result shows a negative allometric growth pattern (b = 2,92) and sex ratio of male to female has a ratio of 1,0: 3,2. The average length of the fish is caught is greater than the length of the first mature gonad (L50% = 57,19 cmTL> Lm = 47,23 cmTL). Analysis of fish population parameter obtained asymptotic length (L) = 111,00cmTL, growth rate (K) = 0,56/year, total mortality rate (Z) = 3,46/year, natural mortality rate (M) = 0,85/year, catch mortality rate (F) = 2,61/year, so that the rate of exploitation (E) = 0,75, indicated fully exploited condition. If left unchecked, the condition may lead to recruitment overfishing. To maintain the sustainability of L. savala resources, management can be done by limiting the intensity of catching, maximazing the mesh size, and determining the reserved area against a sufficient number of parent stocks.

Estimating abundance and biomass of a Speleomantes strinatii (Caudata, Plethodontidae) population by temporary removal sampling

1998 ◽  
Vol 19 (2) ◽  
pp. 113-124 ◽  
Author(s):  
Sebastiano Salvidio
Keyword(s):  
Population Changes ◽  
Age Classes ◽  
Mean Values ◽  
Frequency Distributions ◽  
Rock Face ◽  
Plethodontid Salamanders ◽  
Wet Weight ◽  
Removal Sampling ◽  
Sexually Mature

AbstractA rock-face population of the European plethodontid Speleomantes strinatii (Aellen, 1958) was studied along a small Apennine stream, in northwest Italy. Three temporary removal samples were taken in October, from 1993 to 1996, to estimate population structure, abundance and biomass. Body-size polymodal frequency distributions were resolved into separate components (i.e., estimated age classes) using the log-differences method. Each year's sample was composed of two juvenile age classes plus a mixed component in which large immature individuals and sexually mature salamanders were present. The analysis of removal data showed that capture probabilities were homogeneous within each annual sampling and were similar between juveniles and adults (mean values being 0.33 and 0.26, respectively). The population density varied between 0.6 and 1.0 individuals/m2 of rock face (average 0.8) and biomass, expressed as wet weight, between 0.98 and 1.54 g/m2 (average 1.25 g/m2). Temporary removal sampling was effective in providing autoecological data on European plethodontid salamanders living in such relatively complex microhabitats as vertical rock faces. Moreover, the results suggest that temporary removal methods can be a useful tool in monitoring amphibian long-term population changes.

Comparative Study of effectiveness of mobilization with movement (MWM) and End range mobilization (ERM) techniques in frozen shoulder

2018 ◽  
Vol 4 (4) ◽  
pp. 519-522
Author(s):  
Jeyakumar S ◽  
Jagatheesan Alagesan ◽  
T.S. Muthukumar
Keyword(s):  
Range Of Motion ◽  
Frozen Shoulder ◽  
Type I ◽  
Mean Values ◽  
Functional Activities ◽  
Group A ◽  
The Mean ◽  
Group B

Background: Frozen shoulder is disorder of the connective tissue that limits the normal Range of motion of the shoulder in diabetes, frozen shoulder is thought to be caused by changes to the collagen in the shoulder joint as a result of long term Hypoglycemia. Mobilization is a therapeutic movement of the joint. The goal is to restore normal joint motion and rhythm. The use of mobilization with movement for peripheral joints was developed by mulligan. This technique combines a sustained application of manual technique “gliding” force to the joint with concurrent physiologic motion of joint, either actively or passively. This study aims to find out the effects of mobilization with movement and end range mobilization in frozen shoulder in Type I diabetics. Materials and Methods: 30 subjects both male and female, suffering with shoulder pain and clinically diagnosed with frozen shoulder was recruited for the study and divided into two groups with 15 patients each based on convenient sampling method. Group A patients received mobilization with movement and Group B patients received end range mobilization for three weeks. The outcome measurements were SPADI, Functional hand to back scale, abduction range of motion using goniometer and VAS. Results: The mean values of all parameters showed significant differences in group A as compared to group B in terms of decreased pain, increased abduction range and other outcome measures. Conclusion: Based on the results it has been concluded that treating the type 1 diabetic patient with frozen shoulder, mobilization with movement exercise shows better results than end range mobilization in reducing pain and increase functional activities and mobility in frozen shoulder.

scholarly journals Linking population size structure, heat stress and bleaching responses in a subtropical endemic coral

Coral Reefs ◽  
2021 ◽  
Author(s):  
Liam Lachs ◽  
Brigitte Sommer ◽  
James Cant ◽  
Jessica M. Hodge ◽  
Hamish A. Malcolm ◽  
...  
Keyword(s):  
Heat Stress ◽  
Size Structure ◽  
Temporal Trends ◽  
Early Recovery ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Community Organisation ◽  
Size Frequency ◽  
Eastern Australia

AbstractAnthropocene coral reefs are faced with increasingly severe marine heatwaves and mass coral bleaching mortality events. The ensuing demographic changes to coral assemblages can have long-term impacts on reef community organisation. Thus, understanding the dynamics of subtropical scleractinian coral populations is essential to predict their recovery or extinction post-disturbance. Here we present a 10-yr demographic assessment of a subtropical endemic coral, Pocillopora aliciae (Schmidt-Roach et al. in Zootaxa 3626:576–582, 2013) from the Solitary Islands Marine Park, eastern Australia, paired with long-term temperature records. These coral populations are regularly affected by storms, undergo seasonal thermal variability, and are increasingly impacted by severe marine heatwaves. We examined the demographic processes governing the persistence of these populations using inference from size-frequency distributions based on log-transformed planar area measurements of 7196 coral colonies. Specifically, the size-frequency distribution mean, coefficient of variation, skewness, kurtosis, and coral density were applied to describe population dynamics. Generalised Linear Mixed Effects Models were used to determine temporal trends and test demographic responses to heat stress. Temporal variation in size-frequency distributions revealed various population processes, from recruitment pulses and cohort growth, to bleaching impacts and temperature dependencies. Sporadic recruitment pulses likely support population persistence, illustrated in 2010 by strong positively skewed size-frequency distributions and the highest density of juvenile corals measured during the study. Increasing mean colony size over the following 6 yr indicates further cohort growth of these recruits. Severe heat stress in 2016 resulted in mass bleaching mortality and a 51% decline in coral density. Moderate heat stress in the following years was associated with suppressed P. aliciae recruitment and a lack of early recovery, marked by an exponential decrease of juvenile density (i.e. recruitment) with increasing heat stress. Here, population reliance on sporadic recruitment and susceptibility to heat stress underpin the vulnerability of subtropical coral assemblages to climate change.

scholarly journals High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Atanu Bhattacharya ◽  
Tobias Bolch ◽  
Kriti Mukherjee ◽  
Owen King ◽  
Brian Menounos ◽  
...  
Keyword(s):  
Mass Loss ◽  
River Flow ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
Temperature And Precipitation ◽  
Multi Temporal ◽  
The 1960S ◽  
Northern Tien Shan

AbstractKnowledge about the long-term response of High Mountain Asian glaciers to climatic variations is paramount because of their important role in sustaining Asian river flow. Here, a satellite-based time series of glacier mass balance for seven climatically different regions across High Mountain Asia since the 1960s shows that glacier mass loss rates have persistently increased at most sites. Regional glacier mass budgets ranged from −0.40 ± 0.07 m w.e.a−1 in Central and Northern Tien Shan to −0.06 ± 0.07 m w.e.a−1 in Eastern Pamir, with considerable temporal and spatial variability. Highest rates of mass loss occurred in Central Himalaya and Northern Tien Shan after 2015 and even in regions where glaciers were previously in balance with climate, such as Eastern Pamir, mass losses prevailed in recent years. An increase in summer temperature explains the long-term trend in mass loss and now appears to drive mass loss even in regions formerly sensitive to both temperature and precipitation.

scholarly journals Modeling the Impact of Atmospheric Warming on Staple Crop Growth in China in the 1960s and 2000s

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 36
Author(s):  
Qing Zhang ◽  
Wen Zhang ◽  
Yongqiang Yu ◽  
Tingting Li ◽  
Lijun Yu
Keyword(s):  
Winter Wheat ◽  
Climate Warming ◽  
Northeast China ◽  
Cropping Systems ◽  
Crop Growth ◽  
East China ◽  
Frequency Distributions ◽  
Before And After ◽  
The 1960S ◽  
The Impact

Responses of crop growth to climate warming are fundamental to future food security. The response of crops to climate change may be subtly different at their growing stages. Close insights into the differentiated stage-dependent responses of crops are significantly important in making adaptive adjustments of crops’ phenological optimization and cultivar improvement in diverse cropping systems. Using the Agro-C model, we studied the influence of past climate warming on crops in typical cropping systems in China. The results showed that while the temperature had increased distinctly from the 1960s to 2000s, the temperature frequency distributions in the growth season of crops moved to the high-temperature direction. The low temperature days during the crop growth periods that suppress crop growth decreased in the winter wheat area in North and East China, rice and maize areas in Northeast China, and the optimum temperature days increased significantly. As a result, the above ground biomass (AGB) of rice and maize in Northeast China and winter wheat in North and East China increased distinctly, while that of rice in South China had no significant change. A comparison of the key growth periods before and after heading (silking) showed that the warming before heading (silking) made a great contribution to the increase in the AGB, especially for winter wheat.

scholarly journals A 16-year prospective cohort study to evaluate effects of long-term fluctuations in obesity indices of prediabetics on the incidence of future diabetes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shahla Safari ◽  
Maryam Abdoli ◽  
Masoud Amini ◽  
Ashraf Aminorroaya ◽  
Awat Feizi
Keyword(s):  
High Risk ◽  
Transition Probabilities ◽  
Clinical Settings ◽  
High Tendency ◽  
Mean Values ◽  
Latent Markov Model ◽  
Term Evaluation ◽  
Obesity Indices

AbstractThis study aimed to evaluate the patterns of changes in obesity indices over time in prediabetic subjects and to classify these subjects as either having a low, moderate, and high risk for developing diabetes in the future. This study was conducted among 1228 prediabetics. The patterns of changes in obesity indices based on three measurements including first, mean values during the follow-up period, and last visit from these indices were evaluated by using the latent Markov model (LMM). The mean (standard deviation) age of subjects was 44.0 (6.8) years and 73.6% of them were female. LMM identified three latent states of subjects in terms of change in all anthropometric indices: a low, moderate, and high tendency to progress diabetes with the state sizes (29%, 45%, and 26%), respectively. LMM showed that the probability of transitioning from a low to a moderate tendency to progress diabetes was higher than the other transition probabilities. Based on a long-term evaluation of patterns of changes in obesity indices, our results reemphasized the values of all five obesity indices in clinical settings for identifying high-risk prediabetic subjects for developing diabetes in future and the need for more effective obesity prevention strategies.

scholarly journals MATLAB Virtual Toolbox for Retrospective Rockfall Source Detection and Volume Estimation Using 3D Point Clouds: A Case Study of a Subalpine Molasse Cliff

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Dario Carrea ◽  
Antonio Abellan ◽  
Marc-Henri Derron ◽  
Neal Gauvin ◽  
Michel Jaboyedoff
Keyword(s):  
Point Cloud ◽  
Natural Hazard ◽  
Point Clouds ◽  
Volume Estimation ◽  
Natural Phenomena ◽  
Frequency Distributions ◽  
Erosion Rates ◽  
3D Point Clouds

The use of 3D point clouds to improve the understanding of natural phenomena is currently applied in natural hazard investigations, including the quantification of rockfall activity. However, 3D point cloud treatment is typically accomplished using nondedicated (and not optimal) software. To fill this gap, we present an open-source, specific rockfall package in an object-oriented toolbox developed in the MATLAB® environment. The proposed package offers a complete and semiautomatic 3D solution that spans from extraction to identification and volume estimations of rockfall sources using state-of-the-art methods and newly implemented algorithms. To illustrate the capabilities of this package, we acquired a series of high-quality point clouds in a pilot study area referred to as the La Cornalle cliff (West Switzerland), obtained robust volume estimations at different volumetric scales, and derived rockfall magnitude–frequency distributions, which assisted in the assessment of rockfall activity and long-term erosion rates. An outcome of the case study shows the influence of the volume computation on the magnitude–frequency distribution and ensuing erosion process interpretation.

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