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

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.

An Assessment of the Stocks of the Banana Prawn Penaeus merguiensis in the Gulf of Carpentaria

1979 ◽  
Vol 30 (5) ◽  
pp. 639 ◽  
Author(s):  
C Lucas ◽  
G Kirkwood ◽  
I Somers
Keyword(s):  
Carapace Length ◽  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Mortality Data ◽  
Optimal Size ◽  
Natural Mortality ◽  
Commercial Fishery ◽  
Significant Movement ◽  
Yield Per Recruit

A stock assessment of P. merguiensis in the Gulf of Carpentaria was made by means of a yield per recruit analysis based on studies of migration, growth and mortality. Data were collected both from the commercial fishery and tag recapture experiments. No significant movement of tagged prawns out of the fishing grounds occurred during the fishing season. Estimates of the von Bertalanffy growth parameters (L∞ = 38.0 mm carapace length, K = 0.08 week-1) were obtained from the change in monthly size distribution of commercial catches. The natural mortality coefficient (M) was 0.05 week-1 while the total mortality coefficient (Z) estimates for fishing seasons during 1974-1976, ranged from 0.22 week-1 to 0.35 week-1. The corresponding estimates of the optimal size at first capture ranged from 30.6 to 32.6 mm carapace length. Despite the high rates of exploitation (E = 0.78-0.86), there was no evidence to suggest that recruitment had been adversely affected.

scholarly journals Age, growth, mortality, and exploitation rate of blueline snapper, Lutjanus coeruleolineatus (Actinopterygii: Perciformes: Lutjanidae), from Dhofar Governorate, Sultanate of Oman

2021 ◽  
Vol 51 (2) ◽  
pp. 159-166
Author(s):  
Dawood Almamari ◽  
Said Rabia ◽  
Joo Myun Park ◽  
Laith A. Jawad
Keyword(s):  
Fishery Management ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
Sultanate Of Oman ◽  
Commercial Fish ◽  
Exploitation Rate ◽  
Reported Study

The blueline snapper, Lutjanus coeruleolineatus (Rüppell, 1838), is a significant commercial fish species harvested from the traditional fishery in the Sultanate of Oman. Deficient data on this species, however, make the management strategies challenging, especially in fisheries ecology. A total of 978 specimens were obtained from Dhofar Governorate off the coast of the Arabian Sea during the period between February 2015 and March 2016. In total, 296 sectioned otoliths were analyzed and growth was estimated from non-seasonal growth by using von Bertalanffy method. The parameters of von Bertalanffy growth function, total mortality (Z), natural mortality (M), fishing mortality (F), and exploitation rate (E) were determined and compared with those for Lutjanidae fishes elsewhere. The age structure of male fishes was between 1 and 14 years for males while the age of females ranged from 1 to 18 years. Growth rate (K) was 0.21 y–1 and 0.16 y–1 for males and females, respectively. The hypothetical length of female (L∞ = 46 cm) was relatively higher than that of male (L∞ = 42 cm). The natural mortality (M) was 0.296, total mortality (Z) was 0.372, fishing mortality was 0.076, and exploitation rate (E) was estimated as 0.2. The presently reported study is conducted to examine this fish in relation to growth parameters by analyzing otolith structure. The results of the presently reported study will contribute towards planning the regional fishery management policies in Oman.

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

1994 ◽  
Vol 42 (1-2) ◽  
pp. 113-127 ◽  
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.

scholarly journals POPULATION DYNAMICS OF MALAYAN LEAF FISH (Pristolepisgrooti Blkr.) IN RANAU LAKE, SOUTH SUMATRA

2018 ◽  
Vol 24 (2) ◽  
pp. 125
Author(s):  
Sevi Sawetri ◽  
Subagdja Subagdja ◽  
Dina Muthmainnah
Keyword(s):  
Mortality Rate ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Frequency Data ◽  
Length Frequency ◽  
Lake Ecosystems ◽  
Exploitation Rate ◽  
Length Frequency Data

The Malayan leaf fish or locally named as kepor (Pristolepis grooti) is one of important biotic components in Ranau Lake ecosystems. This study aimed to estimate population dynamic and exploitation rate of kepor in Ranau Lake, South Sumatera. The population parameters are estimated based on length frequency data which were collected in March to October 2013. Growth parameters and fishing mortality rates were calculated using FiSAT software package. The results showed that kepor’s growth was negative allometric, which tended to gain length faster than weight. Kepor population was dominated (42%) by individual length of 10.0 to 11.0 cm. Predicted length infinity (L) was 17.28 cm with high value of growth rates (K) of 1.4 year-1. The natural mortality rate (M) is 2.57 year-1, the fishing mortality rate (F) is 5.36 year-1 and total mortality rate (Z) is 7.93 year-1. The exploitation rate of Malayan leaf fish in Ranau Lake (E = 0.68 year-1) has passed the optimum score.  

scholarly journals Age, growth, mortality and yield per recruit of the dourado Salminus brasiliensis, Corumbá Reservoir, Goiás State, Brazil

2009 ◽  
Vol 7 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Claudenice Dei Tos ◽  
Luiz Carlos Gomes ◽  
Angelo Antônio Agostinho ◽  
Rosana Paulo Batista
Keyword(s):  
Mortality Rate ◽  
Total Mortality ◽  
Fishing Effort ◽  
Average Weight ◽  
Migratory Species ◽  
Reservoir Impoundment ◽  
Annual Total ◽  
One Year ◽  
Yield Per Recruit ◽  
Salminus Brasiliensis

In order to evaluate the fate of the migratory species dourado Salminus brasiliensis in the first years of impoundment in Corumbá Reservoir we estimated age, growth, mortality and yield per recruit. Samplings were carried out monthly in Corumbá Reservoir and its main tributaries (Goiás State) from March 1998 to February 1999 using gillnets. After one year of impoundment, age was estimated from scales and the maximum number of rings was six for males and five for females. Rings are formed annually in May and June. The asymptotic length and growth rate for males and females were 37.1 cm and 0.77 and 56.6 cm and 0.52, respectively. A dominance of juveniles was verified in the reservoir and its tributaries. The instantaneous total mortality rate (Z) was 1.59 and the annual total mortality rate (A) was 79.6%. The highest yield per recruit (1200g) and the highest average weight (1900g) were obtained in simulations with low values of fishing (F) and natural (M) mortalities. Based on the above information we describe the Corumbá Reservoir impoundment has influenced the growth of the dourado. As regards this study, we recommend that the fishing effort not be applied during the trophic upsurge period and that the monitoring of the dourado assemblage continue. Fishery programs management for this species should be carried out with subsequent monitoring involving efficient communication, realistic practices and involvement of fisher organizations.

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.

the population biology of the thornback ray, raja clavata in caernarfon bay, north wales

2005 ◽  
Vol 85 (5) ◽  
pp. 1089-1094 ◽  
Author(s):  
j.m. whittamore ◽  
i.d. mccarthy
Keyword(s):  
Population Biology ◽  
Allee Effect ◽  
Growth Parameters ◽  
Total Mortality ◽  
Von Bertalanffy ◽  
Recruitment Failure ◽  
North Wales ◽  
Thornback Ray ◽  
Raja Clavata ◽  
The Status

amid concern about the status of skates and rays in welsh waters the present work set out to provide up-to-date information on the population biology of raja clavata in caernarfon bay. the von bertalanffy growth parameters were l∞=100.9 cm, k=0.18 y−1 and t0=−0.95 y for males; and l∞=117.6 cm, k=0.16 y−1 and t0=−0.7 y for females. male r. clavata reached 50% maturity at 58.8 cm and 3.9 y, which was smaller and younger than females (l50 and a50 were 70.5 cm and 5.3 y, respectively). although previously over-exploited, the present estimate of total mortality (z) was 0.48–0.49 y−1 which, in terms of replacement mortality (calculated as 0.7 y−1), suggests no immediate prospect of recruitment failure for r. clavata in caernarfon bay. the potential for the recovery of a depleted population is discussed in relation to the allee effect.

scholarly journals DINAMIKA POPULASI IKAN GABUS (Channa striata) DI RAWA DANAU PANGGANG, KALIMANTAN SELATAN

2018 ◽  
Vol 14 (1) ◽  
pp. 16
Author(s):  
Dini Sofarini ◽  
Mohammad Mahmudi ◽  
Asus Maizar S. Hertika ◽  
Endang Yuli Herawati
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Population Dynamic ◽  
Growth Pattern ◽  
Total Mortality ◽  
Natural Mortality ◽  
Von Bertalanffy ◽  
Fishery Resource ◽  
Exploitation Rate ◽  
Channa Striata

The province of South Kalimantan has the largest peat swamp that is named Danau Panggang Swamp with an area of 5,390.7 Ha. This swamp has ecological, economic and potential functions of a large fishery resource. The purposes of this study are to evaluate the exploitation rate of Snake Head Fish (Channa striata) in Danau Panggang Swamp, by population dynamic analysis using FISAT program of Von Bertalanffy method.  The results showed that the growth pattern of Snake Head Fish (Channa striata) has the tendency to grow negative allometric with 63.4 cm of long infifer (L¥), growth rate (k) 0.15 per year, theoretical age at the time of the fish is equal to 0 (t0) is -1.48257 years. While the natural mortality rate (M) was 0.43, the mortality rate due to catch (F) of 0.69/year and the total mortality rate  (Z) of 1.12/year, and the rate of exploitation value E = 0.62.  These results indicated that the exploitation rate of Head Snake Fish (Channa striata) in Danau Panggang swamp has a tendency to overfishing.

scholarly journals Population Dynamics and Management of Invasive Blue Tilapia (Oreochromis aureus) in Garmat Ali River, Basrah, Iraq

2020 ◽  
pp. 44-54
Author(s):  
Abdul-Razak M. Mohamed ◽  
Ayat N. Salman
Keyword(s):  
Population Dynamics ◽  
Growth Parameters ◽  
Relative Yield ◽  
Total Mortality ◽  
Reference Points ◽  
Recruitment Pattern ◽  
Oreochromis Aureus ◽  
Biological Target ◽  
Blue Tilapia ◽  
Yield Per Recruit

The blue tilapia, Oreochromis aureus is an invasive species that has successfully established itself in most of the Iraqi waters. However, there is little information on the population dynamics of the species in these waters. Hence, the growth parameters, mortality rates, probability of capture, recruitment pattern and yield per recruit of blue tilapia in Garmat Ali River, Iraq was assessed using FiSAT II software. A total of 1664 blue tilapia fish were collected by different fishing gears from October 2019 to September 2020 for recording the relevant data. The length-weight relationship obtained was W=0.0147*L3.0748 for fish ranging from 7.5 to 26.3 cm total length suggesting that the species shows positive allometric growth. The asymptotic length (L∞), growth constant (K), theoretical age at zero-length (t0), growth performance index (Ø') and longevity (tmax) were 29.9 cm, 0.205, -1.293, 2.345 and 10.7 years, respectively. The total mortality (Z), natural (M), fishing (F) and exploitation (E) were 1.09, 0.61, 0.48 and 0.43, respectively. Length at first capture (L50) was found to be 13.92 cm. The main recruitment pulse was from March to July with a peak in April, which account for 18.4% of the total recruitment in the year. The relative yield per recruit analysis revealed that the present exploitation rate (Epresent) for blue tilapia was below than the biological target reference points (E0.1 and Emax), which denotes that this stock was not over-exploited. For management purposes, higher yields can be achieved by reducing the mesh sizes of the nets during fishing.

scholarly journals Evaluación de la pesquería de Lutjanus peru (Pisces: Lutjanidae) de . Guerrero, México

1969 ◽  
pp. 571-580
Author(s):  
Apolinar Santamaría ◽  
Ernesto A Chávez
Keyword(s):  
Growth Model ◽  
Population Analysis ◽  
Small Fish ◽  
Natural Mortality ◽  
Von Bertalanffy ◽  
Cohort Size ◽  
Virtual Population ◽  
Von Bertalanffy Growth Model ◽  
Parameter Values ◽  
Yield Per Recruit

Red snapper (Lutjanus peru) fishery was analyzed from landings and catch records. Stock age structure was reconstructed after the parameter values of the von Bertalanffy growth model, the length-weight relationship, ages and the natural mortality coefficient through each of nine years of cateh records. The Pisat software package was applied to assess population parameters, whose estimates are, for the von Bertalanffy growth model, K = 0. 1 442 to 0.38; lo = -0.2; L = 87 cm; W = 9.4 Kg, and the natural mortality coefficient (M) afier several methods (0. 14 to 0.38). Cohort size was assessed by the virtual population analysis (VPA), estlmating population size in 5.2* 1 06 fish with a biomass of 8 454 tonnes. Current fishing mortality P, ranges from 0.06 to 1 . 1 3, depending upon the chosen M value; according to this, when the M value used is low, the results suggest that the stock is nnderexploited, and vice versa. The yield per recruit model applied suggests improvements to the management strategy. The model indicates recruit overfishing because very small fish are the main target (te

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