Yield-per-recruit and egg-per-recruit analyses of the Omani abalone, Haliotis mariae

1995 ◽  
Vol 46 (3) ◽  
pp. 663 ◽  
Author(s):  
SA Shepherd ◽  
JL Baker ◽  
DW Johnson
Keyword(s):  
Mortality Rate ◽  
Sexual Maturity ◽  
Egg Production ◽  
Arabian Sea ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Northern Arabian Sea ◽  
Size At Sexual Maturity ◽  
Yield Per Recruit

The fecundity, size at sexual maturity, sex ratios and total mortality of Haliotis mariae on the Dhofar coast of the northern Arabian Sea were measured. These data, and estimates of the growth rate, were used for yield-per-recruit and egg-per-recruit analyses. Maximum yields occur at 3+ to 4+ years of age, depending on the natural mortality rate chosen. At the present age at first capture egg production levels are 2-29% of the unfished stock, depending on estimates of the fishing mortality rate and the natural mortality rate, and are considered to be far too low to maintain recruitment. At 40% egg production, of the maximum possible the age at first capture is 4 to 4.5 years, i.e. 105-115 mm shell length, depending on site.

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.  

Eggs-per-recruit model for management of the California market squid (Loligo opalescens) fishery

2005 ◽  
Vol 62 (7) ◽  
pp. 1640-1650 ◽  
Author(s):  
Michael R Maxwell ◽  
Larry D Jacobson ◽  
Ramon J Conser
Keyword(s):  
Mortality Rate ◽  
Egg Laying ◽  
Reference Points ◽  
Model Parameters ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Loligo Opalescens ◽  
Maturation Rate ◽  
Sampling Procedures ◽  
Yield Per Recruit

We develop a per-recruit model for the management of the California market squid (Loligo opalescens) fishery. Based on recent confirmation of determinate fecundity in this species, we describe how catch fecundity (i.e., eggs remaining in the reproductive tracts of harvested females) can be used to simultaneously infer fishing mortality rate along with management reference points such as yield-per-recruit, spawned eggs-per-recruit, and proportional egg escapement. Rates of mortality and egg laying have important effects on these reference points. Somewhat surprisingly, increasing the rate of natural mortality decreased spawned eggs-per-recruit while increasing proportional egg escapement. Increasing the rate of egg laying increased both spawned eggs-per-recruit and egg escapement. Other parameters, such as the maturation rate and gear vulnerability of immature females, affected the reference points. In actual practice, the influence of these parameters for immature squid may go undetected if immature squid are excluded from analysis of the catch. Application of this model to routine management is feasible but requires refinement of sampling procedures, biological assumptions, and model parameters. This model is useful because it is grounded on empirical data collected relatively inexpensively from catch samples (catch fecundity) while allowing for the simultaneous calculation of instantaneous fishing mortality rate and egg escapement.

Minimum Size Regulations and the Implications for Yield and Value in the Canadian Atlantic Halibut (Hippoglossus hippoglossus) Fishery

1989 ◽  
Vol 46 (11) ◽  
pp. 1899-1903 ◽  
Author(s):  
John D. Neilson ◽  
W. R. Bowering
Keyword(s):  
Mortality Rate ◽  
Size Composition ◽  
Minimum Size ◽  
Atlantic Halibut ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Hippoglossus Hippoglossus ◽  
Size Regulation ◽  
Size Limit ◽  
Yield Per Recruit

The effect of a minimum size regulation on yield and value per recruit in the Canadian Atlantic halibut fishery was examined. The model indicated that under most scenarios, the size limit would not result in increased yield per recruit. In general, yield per recruit was more sensitive to fishing mortality than age of first entry to the fishery. While reduced yields were usually associated with the minimum size limit, the value per recruit increased with increasing age at entry to the fishery until age 7. The changes in value per recruit reflected the size composition of landings following the imposition of the size limit and the different values associated with various size categories. Both yield and value per recruit were sensitive to the choice of the natural mortality rate.

scholarly journals BEBERAPA PARAMETER POPULASI UDANG PUTIH (Penaeus merguiensis de Mann) DI PERAIRAN TARAKAN, KALIMANTAN UTARA

2017 ◽  
Vol 9 (2) ◽  
pp. 85
Author(s):  
Umi Chodrijah ◽  
Ali Suman
Keyword(s):  
Mortality Rate ◽  
Total Mortality ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Population Parameters ◽  
Spawning Period ◽  
Exploitation Rate ◽  
First Maturity ◽  
Penaeus Merguiensis

Tingkat eksploitasi udang putih (Penaeus merguiensis) sangat intensif. Hal ini terindikasi dengan hasil tangkapan udang di WPP-NRI 716 selama 9 tahun terakhir meningkat. Tujuan penelitian ini untuk mengkaji beberapa parameter populasi dan aspek biologi udang putih di perairan Tarakan. Data panjang karapas dan tingkat kematangan gonad udang putih dikumpulkan dari tempat pendaratan udang di Selumit Pantai, Tarakan, Kalimantan Utara pada Januari sampai dengan November 2016. Pendugaan parameter populasi dengan aplikasi model analisis menggunakan program ELEFAN 1. Hasil penelitian menunjukkan rata-rata ukuran udang putih pertama kali tertangkap (Lc) pada panjang karapas 32,51 mm dan rata-rata ukuran pertama kali matang gonad 33,58 mm. Puncak musim pemijahan terjadi pada Maret dan Agustus. Laju pertumbuhan (K) sebesar 1,33 per tahun (betina) dan 1,55 per tahun (jantan). Laju kematian total (Z) sebesar 7,5 per tahun (betina) dan 8,85 per tahun (jantan), laju kematian alamiah (M) sebesar 1,82 per tahun (betina) dan 2,16 per tahun (jantan) serta laju kematian akibat penangkapan (F) sebesar 5,68 per tahun (betina) dan 6,69 per tahun (jantan). Laju pengusahaan (E) udang putih di perairan Tarakan adalah sebesar 0,76 per tahun. Hal ini menunjukkan tingkat pemanfaatan udang putih telah mengalami lebih tangkap (overfishing). Kondisi ini menggambarkan perlunya dilakukan pengurangan upaya sekitar 52 %.  The banana prawn (Penaeus merguiensis) have been exploited intensively. For instance, within nine years the number of shrimp production in FMA 716 increased dramatically. This research aims to identify the some population parameters of banana prawn in the Tarakan waters. This research was carried out from January to November 2016. Data were analyzed using the analytical model application with ELEFAN I. The result showed that the length at first capture (Lc) of banana prawn was 32,51 mmCL and the length at first maturity (Lm) was 33,58 mm CL. The peak season of spawning period was indicated on March and August. The growth rate (K) was 1,33 /year (female) and 1.55/year (male). Total mortality rate (Z) was 7.5/year (female) and 8,85/year (male), natural mortality rate (M) rate was 1.82/year (female) and 2.16/year (male) and fishing mortality rate ( F) were 5.68/ year (female) and 6.69/year (male). The exploitation rate (E) of banana prawn in the Tarakan waters was 0.76 per year. Therefore, level of existing fishing effort of the banana prawn should reduced about 52 % in the next year.

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.

In what direction should the fishing mortality target change when natural mortality increases within an assessment?

2016 ◽  
Vol 73 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Christopher M. Legault ◽  
Michael C. Palmer
Keyword(s):  
Mortality Rate ◽  
Empirical Evidence ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Stock Assessment ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Limanda Ferruginea ◽  
Trade Offs

Traditionally, the natural mortality rate (M) in a stock assessment is assumed to be constant. When M increases within an assessment, the question arises how to change the fishing mortality rate target (FTarget). Per recruit considerations lead to an increase in FTarget, while limiting total mortality leads to a decrease in FTarget. Application of either approach can result in nonsensical results. Short-term gains in yield associated with high FTarget values should be considered in light of potential losses in future yield if the high total mortality rate leads to a decrease in recruitment. Examples using yellowtail flounder (Limanda ferruginea) and Atlantic cod (Gadus morhua) are used to demonstrate that FTarget can change when M increases within an assessment and to illustrate the consequences of different FTarget values. When a change in M within an assessment is contemplated, first consider the amount and strength of empirical evidence to support the change. When the empirical evidence is not strong, we recommend using a constant M. If strong empirical evidence exists, we recommend estimating FTarget for a range of stock–recruitment relationships and evaluating the trade-offs between risk of overfishing and forgone yield.

scholarly journals Effects of spatial heterogeneity in growth and fishing effort on yield-per-recruit models: an application to the US Atlantic sea scallop fishery

2015 ◽  
Vol 73 (4) ◽  
pp. 1062-1073 ◽  
Author(s):  
Samuel B. Truesdell ◽  
Deborah R. Hart ◽  
Yong Chen
Keyword(s):  
Spatial Heterogeneity ◽  
Spatial Data ◽  
Egg Production ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Sea Scallop ◽  
The Us ◽  
The Impact ◽  
Yield Per Recruit

Abstract Conventional yield-per-recruit (Y/R) and spawning-stock biomass-per-recruit (SSB/R) models make no allowance for spatial heterogeneity in fishing mortality, natural mortality, or growth across the stock area, although variability in these processes can affect model results. For example, areas with higher growth and/or lower natural mortality rates should be fished at a lower rate to maximize Y/R; however, these areas may be especially attractive to fishers and are often fished harder. Here, Y/R and SSB/R models are developed that simultaneously account for spatial heterogeneity in growth and fishing effort. These models are applied to the US Atlantic sea scallop (Placopecten magellanicus) fishery. The spatial variability in growth uses depth-integrated models from the literature and variability in effort is based on, alternatively, uniform, observed, and relative-optimal spatial harvesting distributions. The observed effort patterns are derived from vessel monitoring system positions, and illustrate one application for these widely collected but underutilized spatial data. In this example, the distribution of observed fishing effort reduces Y/R compared with the relative-optimal, or the uniform effort distribution implicitly assumed by conventional Y/R analysis. SSB/R was in some cases considerably higher under the relative-optimal distribution of effort than when calculated using observed or uniform effort patterns. Such more realistic spatially integrated Y/R and SSB/R models can help to evaluate the impact of effort patterns on fishery yield and stock egg production. These models demonstrate that the spatial distribution of effort can be as important as the overall average fishing mortality when managing fisheries to optimize Y/R, SSB/R, and yield.

scholarly journals Biological Parameters of False Scad (Decapterus Rhonchus) Encountered in the Coastal Waters of Elmina, Ghana

2020 ◽  
Vol 7 (3) ◽  
pp. 507-515
Author(s):  
Stella Forson ◽  
Samuel KK Amponsah
Keyword(s):  
Mortality Rate ◽  
Coastal Waters ◽  
Total Mortality ◽  
R Package ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Management Measures ◽  
Fish Samples ◽  
Exploitation Rate ◽  
Landing Beach

The study evaluated some population parameters of Decapterus rhonchus in coastal waters of Elmina, Ghana. A total of 210 samples were collected from Elmina landing beach in the Central region of Ghana from July 2019 to December 2019. The total length of individual fish samples was measured and analyzed using TropFish R package. Von Bertalanffy parameters were estimated as asymptotic length (L∞) = 40.6 cm, growth rate (K) = 0.14 per year, and growth performance index (Φ′) =2.367 per year. The length at first capture and maturity were 28.2 cm and 23.2 cm, respectively. Mortality parameters were calculated as total mortality rate (Z) = 1.09 per year, natural mortality rate (M) = 0.29 per year and fishing mortality rate (F) = 0.80 per year. The exploitation rate (E) was 0.73 which suggests that Decapterus rhonchus fishery in coast of Elmina, Ghana is highly overexploited. Reduction of fishing efforts through the removal of subsidies and the introduction of closed fishing season are some of the recommended management measures to sustain the Decapterus rhonchus fishery in Ghana. Res. Agric., Livest. Fish.7(3): 507-515,  December 2020

scholarly journals KARAKTERISTIK POPULASI UDANG JERBUNG (Penaeus merguiensis de Man, 1888) DI PERAIRAN CILACAP DAN SEKITARNYA

2017 ◽  
Vol 23 (1) ◽  
pp. 11
Author(s):  
Ali Suman ◽  
Budi Iskandar Prisantoso
Keyword(s):  
Mortality Rate ◽  
Carapace Length ◽  
Total Mortality ◽  
Survey Method ◽  
Natural Mortality ◽  
Market Demand ◽  
Fishing Mortality ◽  
Population Characteristic ◽  
Exploitation Rate ◽  
De Man

Tingginya permintaan pasar terhadap udang jerbung mengakibatkan aktivitas penangkapannya berlangsung secara terus-menerus sepanjang tahun sehingga mengancam kelestariannya. Penelitian karakteristik populasi merupakan salah satu dasar utama dalam merumuskan pengelolaan menuju pemanfaatannya secara lestari. Tujuan penelitian ini adalah untuk mengetahui karakteristik populasi udang jerbung di perairan Cilacap dan sekitarnya. Penelitian dilakukan dari bulan Januari sampai dengan Nopember 2013 dengan metode survey. Hasil penelitian menunjukkan bahwa rata-rata ukuran panjang pertama kali matang kelamin (Lm) udang jerbung di perairan Cilacap dan sekitarnya adalah pada panjang karapas 38,3 mm dan musim pemijahan berlangsung sepanjang tahun dengan puncaknya pada bulan Januari. Laju pertumbuhan udang jerbung jantan adalah 1,00 per tahun dan panjang karapas maksimum (L ) adalah 40,7 mm serta untuk udang betina didapatkan nilai K adalah 1,10 per tahun dan nilai Loo adalah 54,2 mm. Laju kematian total (Z) udang jerbung jantan adalah 2,46 per tahun, laju kematian karena penangkapan (F) dan laju kematian alami (M) masing-masing 1,37 per tahun dan 1,09 per tahun. Untuk udang betina didapatkan nilai Z adalah 1,69 per tahun, nilai F dan nilai M masing-masing 0,61 dan 1,08 per tahun. Laju pengusahaan (E) udang jerbung jantan adalah 0,56 per tahun dan nilai E udang betina adalah 0,36 per tahun. Pola penambahan baru udang jerbung di perairan Cilacap berlansung sepanjang tahun dengan puncaknya pada bulan Maret dan April. Tingkat pemanfaatan udang jerbung jantan sudah berada dalam tahapan overfishing dan perlu dilakukan pengurangan jumlah upaya.High market demand of banana prawn have consequence in fishingactivities which is carried out continuously throughout the year, so that could be threaten of resources sustainability. Scientific advices on the population characteristic are required as an input to support fisheries management. The purpose of the study was to identify population characteristic of the banana prawn with survey method. Study on the population characteristic of banana prawn (P. merguiensis de Man) was conducted in Cilacap and the surrounding waters based on data collected during, January 2013 to November 2013. Result showed that the size at first maturity (Lm) of banana prawn was 38.3 mm in carapace length. The spawning season of banana prawn in Cilacap and the surrounding waters occures throughout the year with the peak in January. The growth parameters of male (K) was 1.0/year with maximum carapace length (L ) of 40.7 mm and K for female was 1.10/year with maximum carapace length of 54,2 mm. Instantaneous total mortality rate (Z) and natural mortality rate (M) of male were 2.46/year and 1.09/year, respectively. While fishing mortality (F) and exploitation rate (E) respectively were 1.37/year and 0.56/year. The total mortality (Z) and natural mortality (M) of female  respectively were 1.69/year and 1.08/year. Fishing mortality (F) and exploitation rate (E) were 0.61/ year and 0.36/year. The recruitment pattern of banana prawn in Cilacap and surrounding waters occures throughout the year with two peaks in March and April. The exploitation rate of male of banana prawn fisheries in Cilacap waters was high. It was, therefore, recommended that fishing effort of the banana prawn in that waters should be reduced in the next year.

scholarly journals Growth Pattern, Mortality and Exploitation Rate of the Giant African Threadfin, Polydactylus quadrifilis (Cuvier, 1829) from Ebrié Lagoon (Potou Sector, Côte d’Ivoire)

2020 ◽  
pp. 33-42
Author(s):  
Théophile Aké Bédia ◽  
Bakari Coulibaly ◽  
Yao Aristide Konan ◽  
Essetchi Paul Kouamelan ◽  
Valentin N’douba
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Growth Pattern ◽  
Total Mortality ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Population Parameters ◽  
Exploitation Rate ◽  
First Maturity

The study evaluated some population parameters of Polydactylus quadrifilis within Ebrié lagoon (Potou sector). Samples were obtained using artisanal gillnet fishery from April 2004 to March 2006. A total of 741 individuals of P. quadrifilis ranged from 11 to 70 cm were examined. Population parameters were estimated where asymptotic length (L∞) was found 60 cm, growth rate (K) 0.33 per year, the longevity (T max) 9.09 years, and growth performance index (Φ′) 3.06. The length at first capture (Lc50 = 10.60 cm) was lower than the length at first maturity (Lm50 = 40 cm). Total mortality rate (Z) was calculated as 1.10 per year including natural mortality and fishing mortality. The exploitation rate (E=0.36) was found to be less than the maximum exploitation rate (E max = 0.44) and indicated that P. quadrifilis is not overexploited. The current exploitation rate should be maintained by sustainable fisheries measures including monitoring of fishing effort.

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