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

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.

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

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315414001337 ◽

2014 ◽

Vol 95 (2) ◽

pp. 381-390 ◽

Cited By ~ 4

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.

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

ICES Journal of Marine Science ◽

10.1093/icesjms/fsq003 ◽

2010 ◽

Vol 67 (5) ◽

pp. 875-884 ◽

Cited By ~ 14

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).

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Yield-per-Recruit and Relative Mean Biomass Estimates, and their Management Consequences, to the Penaeus Indicus Fishery in the Gulf of Masirah

Journal of Agricultural and Marine Sciences [JAMS] ◽

10.24200/jams.vol1iss0pp51-55 ◽

1996 ◽

Vol 1 ◽

pp. 51

Author(s):

M. S. M. Siddeek ◽

R. Mohan ◽

D. W. Johnson

Keyword(s):

Growth Parameters ◽

Total Mortality ◽

High Yield ◽

Average Weight ◽

Natural Mortality ◽

Von Bertalanffy ◽

Fishing Season ◽

Penaeus Indicus ◽

Length Data ◽

Yield Per Recruit

The von Bertalanffy growth parameters estimated based on the 1990/91 carapace length data of Penaeus indicus from the Gulf of Masirah, Oman were used to calculate total mortality, yield-per-recruit ( i.e. average weight of a shrimp from a cohort under a given fishing pattern) , and relative mean biomass ( i.e. exploited cohort biomass over un-exploited cohort biomass) for the population sampled. The instantaneous total mortality coefficient value indicated under exploitation in 1990/91. When different fishing seasons scenarios were considered with the current total mortality level but with a range of natural mortality values, high yield, per recruit and relative mean biomass values were shown for October-April and November-April fishing seasons. The fishing season is currently late August to end of April. Thus, a one to two-month delay in the fishing season appears to be beneficial to this fishery.

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A Bayesian approach for overcoming inconsistencies in mortality estimates using, as an example, data for Acanthopagrus latus

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f04-074 ◽

2004 ◽

Vol 61 (7) ◽

pp. 1202-1211 ◽

Cited By ~ 12

Author(s):

Norman G Hall ◽

S Alex Hesp ◽

Ian C Potter

Keyword(s):

Life History ◽

Bayesian Approach ◽

Growth Parameters ◽

Probability Distributions ◽

Total Mortality ◽

Growth Parameter ◽

Life History Parameters ◽

Acanthopagrus Latus ◽

Marine Embayment ◽

Mortality Estimates

Reliable estimates of natural (M) and total mortality (Z) are essential for effective fisheries management. However, estimates of M, which are frequently determined from life history parameters, are imprecise and often inconsistent with the values of Z derived from life history parameters and other analyses. This is exemplified by the mortality estimates derived for Acanthopagrus latus in a large marine embayment. Thus, such estimates, calculated for M for this population from a growth parameter and from growth parameters and water temperature, were both 0.70·year1, whereas those for Z, calculated from maximum recorded age, relative abundance analysis, and a simulation based on maximum age and sample size, ranged from 0.18 to 0.30·year1. These results are clearly inconsistent. A Bayesian approach was therefore developed that combines the posterior probability distributions of the various mortality estimates and thereby produces integrated and consistent estimates for M and Z. The application of our Bayesian approach to the data for A. latus yielded lower values for M than for Z. Our approach is equally applicable to other fish species.

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Less known aspects of Penaeus kerathurus (Forskål, 1775) (Decapoda, Penaeidae) obtained from the fishermen in the Sea of Marmara: age, growth, and mortality rates

Crustaceana ◽

10.1163/15685403-bja10080 ◽

2020 ◽

Vol 93 (9-10) ◽

pp. 1185-1195

Author(s):

M. Arslan İhsanoğlu

Keyword(s):

Growth Parameters ◽

Economic Value ◽

Age Groups ◽

Length Distribution ◽

Total Mortality ◽

Mortality Rates ◽

Natural Mortality ◽

Sea Of Marmara ◽

Age Composition ◽

Important Species

Abstract Penaeus kerathurus is an important species for the fishery, thanks to its high nutritional and economic value. Therefore, this study attempts to determine the length distribution, length-weight relationship, age composition, growth parameters, and mortality rates of a population of P. kerathurus. The material was monthly collected from commercial fishermen in and around Karabiga and the Gulf of Erdek in the Sea of Marmara, between May 2018 and April 2019. The carapace length-weight relationships were calculated as W = 0.0023 × CL2.57, W = 0.0036 × CL2.46, and W = 0.0026 × CL2.56 for the females, males and both sexes combined, respectively. The population studied was distinguished into four age groups, and the tmax (= maximum theoretical age) was found to be reached at 11.9 year. The growth parameters were observed to be = 60.9 mm; K = 0.24 year−1, and t0 = −0.58 year. The rates of total mortality (Z), natural mortality (M), fisheries mortality (F), and exploitation (E) were calculated to be 1.32, 0.43, 0.89, and 0.67, respectively. The results showed that P. kerathurus suffers from a heavy fishing pressure in the sampled area.

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Growth and mortality estimates of Sardinella brasiliensis in the southeastern Brazilian Bight

Boletim do Instituto Oceanográfico ◽

10.1590/s0373-55241994000100009 ◽

1994 ◽

Vol 42 (1-2) ◽

pp. 113-127 ◽

Cited By ~ 4

Author(s):

Maria Cristina Cergole ◽

Helio Valentini

Keyword(s):

Growth Parameters ◽

Total Mortality ◽

Entire Period ◽

Brazilian Coast ◽

Growth Equation ◽

Natural Mortality ◽

Length Data ◽

The Mean ◽

The Difference ◽

Von Bertalanffy Growth Equation

Length frequency analisys were applied for sardine data collected from commercial catches throughout the southeastern Brazilian coast in 1977-1987. Age/length keys were obtained by otolith ring countings and utilized to transform length into age composition. Growth parameters were estimated by the von Bertalanffy growth equation using age and length data for each year and for all the period of investigation. The mean growth parameters for the entire period were estimated as L∞ = 271 mm and K= 0.59 year-1. Instantaneous total mortality (Z) coefficients per year were estimated using catch curves and methods based on the mean length of the fish caught. Total mortality rate for the entire period was obtained through the average of the annual values. Natural mortality (M) was estimated using the Paul/s empirical equation (1980a), and fishing mortality (F) by the difference between total and natural mortality values.The results were Z = 3.6 year-1; M = 0.96 year-1; and F= 2.6 year-1.

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Electron Probe Analysis of Vertebrate Smooth Muscle: Distribution of Ca and Ci

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091652 ◽

1976 ◽

Vol 34 ◽

pp. 334-335 ◽

Cited By ~ 1

Author(s):

Avril V. Somlyo ◽

H. Shuman ◽

A.P. Somlyo

Keyword(s):

Smooth Muscle ◽

Electron Probe ◽

Preliminary Report ◽

Cell Damage ◽

Electron Probe Analysis ◽

Perinuclear Space ◽

Probe Analysis ◽

High K ◽

Low K ◽

Initial Results

This is a preliminary report of electron probe analysis of rabbit portal-anterior mesenteric vein (PAMV) smooth muscle cryosectioned without fixation or cryoprotection. The instrumentation and method of electron probe quantitation used (1) and our initial results with cardiac (2) and skeletal (3) muscle have been presented elsewhere.In preparations depolarized with high K (K2SO4) solution, significant calcium peaks were detected over the sarcoplasmic reticulum (Fig 1 and 2) and the continuous perinuclear space. In some of the fibers there were also significant (up to 200 mM/kg dry wt) calcium peaks over the mitochondria. However, in smooth muscle that was not depolarized, high mitochondrial Ca was found in fibers that also contained elevated Na and low K (Fig 3). Therefore, the possibility that these Ca-loaded mitochondria are indicative of cell damage remains to be ruled out.

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Plasma surface interactions in nanoscale processing: Preservation of low-k integrity and high-k gate-stack etching with Si selectivity

10.31274/etd-180810-312 ◽

2012 ◽

Author(s):

Juline Shoeb

Keyword(s):

Surface Interactions ◽

Gate Stack ◽

Plasma Surface ◽

Plasma Surface Interactions ◽

High K ◽

Low K

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Some biological properties of spiny eel (Mastacembelus mastacembelus, Banks & Solander, 1794) living in the Upper Euphrates River Basin, Turkey

Scientific Reports ◽

10.1038/s41598-021-91223-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mehmet Zülfü Çoban ◽

Mücahit Eroğlu ◽

Mustafa Düşükcan

Keyword(s):

River Basin ◽

Growth Parameters ◽

Age Groups ◽

Mortality Rates ◽

Biological Properties ◽

Von Bertalanffy ◽

Growth Type ◽

Euphrates River ◽

Fish Samples ◽

Exploitation Rate

AbstractThis study was carried out to determine some bioecological characteristics of Mastacembelus mastacembelus, which is the only species of Mastacembelidae family living in Turkey. Fish samples were caught between 2014–2018 from Keban Dam Lake, one of the most important reservoirs of the upper Euphrates Basin. In totally, 348 Mastacembelus mastacembelus individuals were examined, including 178 males and 170 females. The age distributions were defined between the I–XV age groups. Total lengths ranged from 14.20 to 81.80 cm in males and from 15.60 to 77.30 cm in females. Total length–weight relationships were calculated as W = 0.0083 × TL2.6516 for males, W = 0.0043 × TL2.8310 for females and W = 0.0063 × TL2.7256 for all population, and the growth type was estimated as “negative allometric”. The von Bertalanffy growth parameters for all individuals were computed as L∞ = 90.99, k = 0.13, t0 = − 0.45. The total (Z), natural (M), fishing (F) mortality rates and exploitation rate (E) were estimated as Z = 0.313, M = 0.270, F = 0.043 and E = 0.137, respectively. The length at first capture (Lc) was found as 50.72. The optimum, maximum and economic yields were calculated as E0.5 = 0.361; Emax = 0.776; E0.1 = 0.664, respectively.

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