scholarly journals Relative yield-per-recruit and management strategies for Cynoscion acoupa (Perciformes: Sciaenidae) in Lake Maracaibo, Venezuela

2013 ◽  
Vol 61 (1) ◽  
Author(s):  
Orlando José Ferrer Montaño ◽  
Isabel Cristina Morales
Keyword(s):  
Management Strategies ◽  
Relative Yield ◽  
Lake Maracaibo ◽  
Yield Per Recruit

scholarly journals Growth, mortality, exploitation rate and recruitment pattern of Octopus cyanea (Mollusca: Cephalopoda) in the WIO region: A case study from the Mafia Archipelago, Tanzania

2021 ◽  
Vol 20 (1) ◽  
pp. 71-79
Author(s):  
Mathew O. Silas ◽  
Mary A. Kishe ◽  
Johnson G. Mshana ◽  
Masumbuko L. Semba ◽  
Said S. Mgeleka ◽  
...  
Keyword(s):  
Population Analysis ◽  
Scientific Information ◽  
Management Strategies ◽  
Relative Yield ◽  
Western Indian Ocean ◽  
Maximum Sustainable Yield ◽  
Differential Mortality ◽  
Recruitment Pattern ◽  
Exploitation Rate ◽  
Yield Per Recruit

Octopus cyanea is a commercially important cephalopod in the Western Indian Ocean (WIO) region, but scientific information to inform management strategies for the species is limited. A study was conducted in 2014, 2015, 2017 and 2018 to investigate biological parameters including growth, mortality, exploitation rates and recruitment patterns in the sea around Mafia Archipelago, Tanzania. Virtual population analysis (VPA) indicated differential mortality between two sampling sites; the lowest and highest fishing mortality of F = 1.5yr-1 and F = 2.7yr-1 were observed in Bwejuu (Dorsal mantle length, DMT = 18-20 cm) and Jibondo (DMT = 8-12 cm) fishing villages, respectively. The maximum exploitation rate (Emax), which gives the maximum relative yield per recruit, was estimated at 0.380 and 0.379 for Jibondo and Bwejuu, respectively. The exploitation rates E 0.5, which corresponded to 50% of the unexploited stock relative biomass per recruit, were estimated at 0.248 for Jibondo and 0.247 for Bwejuu. These values differ greatly from the exploitation rates of 0.53 and 0.41 for Jibondo and Bwejuu, respectively, suggesting that the stock of O. cyanea is probably being overfished both in terms of yield per recruit and biomass per recruit. The stock-recruit pattern was observed to be continuous year-round, with the peak being between May and July. Since the peak in recruitment of both areas coincides with the south-east monsoon (SE Monsoon) and the level of maximum sustainable yield has been overshot, it is recommended that management plans are implemented that will reduce effort while increasing biomass, for example, implementing temporal octopus fishery closures at a village level.

scholarly journals Growth , Mortality and Relative Yield per Recruit of Japanese Scad Decapterus Maruadsi ( Temminck and Schlegel , 1842 ) in the Gulf of Suez , Red Sea , Egypt

2015 ◽  
Vol 19 (1) ◽  
pp. 1-6
Author(s):  
Mahmoud H. M. Ahmed ◽  
Magdy T. Khalil ◽  
Sahar F. Mehanna ◽  
Sameh B. El-Kafrawy ◽  
Asaar S. H. El-Sherbeny
Keyword(s):  
Red Sea ◽  
Relative Yield ◽  
Gulf Of Suez ◽  
Yield Per Recruit ◽  
Decapterus Maruadsi

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 Evaluation of current and alternative fisheries management scenarios based on spawning-per-recruit (SPR), revenue-per-recruit (RPR), and yield-per-recruit (YPR) diagrams

2005 ◽  
Vol 62 (5) ◽  
pp. 841-846 ◽  
Author(s):  
T. Katsukawa
Keyword(s):  
Fisheries Management ◽  
Numerical Optimization ◽  
Management Strategy ◽  
Management Strategies ◽  
Management Scenarios ◽  
Trade Off ◽  
Contour Lines ◽  
Stock Assessments ◽  
Optimal Harvest ◽  
Yield Per Recruit

Abstract Spawning-per-recruit (SPR) and yield-per-recruit (YPR) analyses are widely used in stock assessments of exploited fish populations. In decision-making for fisheries management, the trade-off between fisheries production (YPR) and stock reproduction (SPR) is important. The general outputs of SPR and YPR analysis, such as single variate plots with contour lines or optimal harvest strategies estimated by numerical optimization, are inappropriate in obtaining an overview of the trade-off. This paper introduces a diagram that expresses graphically the bivariate trade-off between YPR and SPR. The method was applied to chub mackerel (Scomber japonicus) data, and two management scenarios were compared using the SPR–YPR diagram. Differences between YPR and revenue-per-recruit (RPR) were also considered. The results showed that: (i) current estimated fishing mortality is suggestive of growth-overfishing, and there is room for improving SPR and YPR simultaneously; (ii) increasing the age at first capture is more effective than effort control; (iii) management strategies that maximize landing weight or revenue are significantly different. The management strategy that maximizes landing weight, when considered from the viewpoint of maximizing revenue, results in growth-overfishing.

scholarly journals Sustainable harvest of two large predatory catfish in the Cuiabá river basin, northern Pantanal, Brazil

2007 ◽  
Vol 67 (1) ◽  
pp. 81-89 ◽  
Author(s):  
JMF. Penha ◽  
LAF. Mateus
Keyword(s):  
River Basin ◽  
Economic Activity ◽  
Relative Yield ◽  
Commercial Fishing ◽  
Fishing Mortality ◽  
Stock Management ◽  
Sustainable Harvest ◽  
Mato Grosso ◽  
Stock Recruitment ◽  
Yield Per Recruit

Fishery is an important economic activity in the Pantanal. Among the region’s species, the Pimelodidae catfish stands out as an important part of the annual catch. This study assesses the structure, exploitation and stock management of Hemisorubim platyrhynchos and Sorubim cf. lima, the sixth and seventh largest Pimelodidae of the Pantanal. The analysis is based on fish caught by commercial fishing in the Cuiabá river and landed at the "Antônio Moysés Nadaf" Market in the Cuiabá city, Mato Grosso state, Brazil. The findings indicate that commercial fishing activities target several fish cohorts and that usually only individuals above mean length at first maturation are caught. Estimates of the instantaneous mortality coefficient show that the current fishing mortality is low. Simulations of relative yield-per-recruit model demonstrate that the current yield of two species could be greater if the fishery effort were increased, indicating that the stocks are underexploited. However, an increase in current fishery efforts should be viewed with caution, since the stock-recruitment relationship for the species is unknown. The results indicate that the current harvest of two species in the Cuiabá River Basin is sustainable.

Demography, fishery yield and potential management strategies of painted spiny lobster (Panulirus versicolor) at Northwest Island, Great Barrier Reef, Australia

2012 ◽  
Vol 63 (5) ◽  
pp. 387
Author(s):  
Ashley J. Frisch ◽  
Jean-Paul A. Hobbs
Keyword(s):  
Great Barrier Reef ◽  
Fishery Management ◽  
Spiny Lobster ◽  
Management Strategies ◽  
Minimum Size ◽  
Demographic Parameters ◽  
Barrier Reef ◽  
Minimal Impact ◽  
Demographic Processes ◽  
Yield Per Recruit

Quantification of demographic parameters is important for understanding how populations interact with their environment and for developing sustainable harvest strategies. Our aims were to quantify demographic parameters and yield of painted spiny lobster (Panulirus versicolor) at Northwest Island, Great Barrier Reef and review fishery management regulations in view of the findings. Using catch-curve analysis and an intensive mark–recapture program, the local lobster population was found to be sparsely distributed (~1.3 ha–1), with low rates of natural mortality (0.25–0.28 year–1) and immigration (0.05 ha–1 year–1). Under current management regulations (no minimum size limit; MSL), yield-per-recruit peaked at 0.38 kg when fishing mortality was 0.4 year–1. Implementation of a 100-mm (carapace length) MSL is recommended because it provides the best compromise between yield and stock size and has minimal impact on existing fishing practices. Revocation of the prohibition on possessing egg-bearing females is also recommended because it would reduce wastage of lobsters that are inadvertently killed by spear-fishers and because there appears to be little chance of localised recruitment overfishing. This study provides the first estimate of mortality rate for P. versicolor and highlights the importance of this parameter for understanding demographic processes and optimising management regulations.

scholarly journals GROWTH AND EXPLOITATION STATUS (Channa striata Bloch, 1793) IN LUBUK LAMPAM FLOODPLAINS, SOUTH SUMATERA

2013 ◽  
Vol 19 (1) ◽  
pp. 1
Author(s):  
Zulkarnaen Fahmi ◽  
Syarifah Nurdawati ◽  
Freddy Supriyadi
Keyword(s):  
Relative Yield ◽  
Total Mortality ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Population Parameters ◽  
Future Plan ◽  
Channa Striata ◽  
Exploitation Status ◽  
Yield Per Recruit

Due to the economic importance of C. striata in Lubuk Lampam floodplains (Indonesia), this study is aimed to estimate the biological and population parameters required for proposing a future plan to sustain and manage this valuable fish resource. The growth, mortality and explotation ratio of <em>Channa striata</em> estimated by employing FiSATProgramme are reported. The parameters of Von Bertalanffy growth model of 1,529 sample fishes were estimated as K= 0.36/ year, L” = 72.98 cm and to = -0.52 year. The coefficients of total mortality (Z), natural mortality (M) and fishing mortality (F) were 1.72, 0.73 and 0.99 year-1 respectively. Relative yield per recruit analysis shows that the presentexploitation rate (E) was 0.58. Yield per recruit can be maximized at the exploitation ratio of 0.5 and Lc/Linf values of 0.3. The Yield per recruit and biomass per recruit models indicated that, the fisheries status of <em>C. striata</em> in Lubuk Lampam floodplains exceed the limit reference point (Fmax), thus stock of this species in Lubuk Lampam floodplains is indicated being driving down.Reduction in fishing effort and increase number of selective fishing gears are suggested to sustain the fishery of <em>Channa striata</em> in Lubuk Lampam floodplains.

scholarly journals Population Dynamics of Two Cichlids, Oreochromis aureus and Tilapia zilIi, from Wadi EI-Raiyan Lakes, Egypt

2004 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
S.F. Mehanna
Keyword(s):  
Population Dynamics ◽  
Relative Yield ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
Oreochromis Aureus ◽  
Exploitation Rate ◽  
Growth Equations ◽  
Yield Per Recruit

Age, growth, mortality, relative yield-per-recruit and relative biomass-per-recruit of Oreochromis aureus and Tilapia zilli collected from Wadi EI-Raiyan lakes during the period from August 2000 until July 2001 have been estimated. Age was determined from scale readings and the results showed that the maximum life spans of O. aureus and T. zilli were three and four years, respectively. The von Bertalanffy growth equations were L1= 27.15 (l-e'0.56(t+0.32) for 0. aureus and L1= 33.5 (l-e -0.49(t+0.15) for T. zilli. The instantaneous annual rates of total, natural and fishing mortality were calculated as 1.69, 0.25 and 1.44, respectively for 0. aureus and 1.1, 0.2 and 0.9, respectively for T. zilli. Exploitation rate was estimated as 0.85 and 0.82 for 0. aureus and T. zilli, respectively. Relative yield-per- recruit and relative biomass-per-recruit analysis indicated that the stocks of O. aureus and T. zilli were overexploited and that the current exploitation rate should be reduced by about 53% for 0. aureus and 55% for T. zilli to ensure that at least 50% of the individuals could be maintained for spawning and recruitment.  

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