scholarly journals Growth, Mortality and Exploitation Rate of Pagellus bellottii Harvested from the Marine Territorial Waters of Sierra Leone

2021 ◽  
Vol 8 (2) ◽  
pp. 60
Author(s):  
Komba Jossie Konoyima ◽  
Lahai Duramany Seisay
Keyword(s):  
Mortality Rate ◽  
Life Span ◽  
Sierra Leone ◽  
Growth Parameters ◽  
Optimal Level ◽  
Fishing Mortality ◽  
Exploitation Rate ◽  
Size Growth ◽  
Constant Class ◽  
First Maturity

The study investigated growth, mortality and exploitation rate of Pagellus bellottii collected off Sierra Leone, aimed to support efficient management of its stock.  A total of 8, 216 specimens of Pagellus bellottii were collected at random from January-November, 2016 on-board a demersal trawler. Data analysis employed methods implemented in the computerized FiSAT II software using pooled length-frequencies in constant class size. Growth parameters gave asymptotic length (L∞ = 33.63cm), growth rate (K = 0.63yr-1), growth performance index (ɸ = 2.85), theoretical age (to = -0.6years) and life-span (tmax = 5.50years) whereas the length (Lm50) and age (tm50) at first maturity were estimated as 22.40 cm and 2.30years respectively. Besides, the current fishing mortality rate (F = 6.58yr-1) exceeded the optimum (Fopt = 0.50yr-1), limiting (Flimit = 0.81yr-1) and natural (M = 1.22yr-1) mortality rates, and the current exploitation rate (Ecurrent) was 0.84yr-1. Results depicted low life expectancy, fast growth and late first maturity (Lm50 = 33.4%, but < L∞) in Pagellus bellottii. Also, the stock of P. bellottii was overexploited (Ecurrent > 0.5), buttressed by the alarming current fishing mortality beyond optimal and permissible limits. This was very worrisome and the current exploitation rate should be reduced to 0.5yr-1 (40.5%) and fishing mortality rate to 0.5yr-1 (92.4%) in order to achieve at least optimal level of exploitation (Ecurrent = 0.5) and fishing mortality rate (Fcurrent = Fopt) respectively, through institution of closed fishing seasons and reduction in fleets targeting the species.Keywords: Exploitation; growth;  life-span; mortality; stock 

scholarly journals Aspects of Population Dynamics of Pagrus Caeruleostictus Collected From the Continental Shelf of Sierra Leone and the Implications for Management

2020 ◽  
Vol 7 (3) ◽  
pp. 517-531
Author(s):  
Komba Jossie Konoyima ◽  
Lahai Duramany Seisay
Keyword(s):  
Population Dynamics ◽  
Mortality Rate ◽  
Life Span ◽  
Sierra Leone ◽  
Growth Parameters ◽  
Growth Exponent ◽  
High Survival ◽  
Fishing Mortality ◽  
Randomized Sampling ◽  
First Maturity

The study evaluated aspects of population dynamics of Pagruscaeruleostictus and the implications for management in Sierra Leone, needed to support efficient management plans of its fishery. 12, 729 specimens of Pagruscaeruleostictus were collected off Sierra Leone from January-November, 2016 using randomized sampling techniques on-board demersal trawler. Analysis of population dynamics employed methods fitted in FiSAT II software using pooled length-frequencies. Estimated growth parameters were asymptotic length (L∞ = 34.48cm) and weight (W∞ = 4693.6g), growth rate (K = 0.29yr-1), growth performance index (ɸ = 2.54), growth exponent (b = 3.09), theoretical age (to = -0.8years) and life-span (tmax = 9.50years). The instantaneous fishing mortality rate (F = 0.40yr-1) climaxed the optimum fishing mortality rate (Fopt = 0.30yr-1) and slightly below the limiting fishing mortality (Flimit = 0.51yr-1) whereas natural mortality rate (M) gave 0.76yr-1. Besides, the estimated current exploitation rate (Ecurrent) exceeded the estimated sustainable level of exploitation (E50 = 0.39yr-1) but below the estimated maximum allowable exploitation point (Emax = 1.10yr-1). Further, the length (Lm50 = 23.00cm) and age (tm50 = 4.60years) at first maturity climaxed the length and age at first capture (Lc50 = 21.64cm, tc50 = 3.8years,), length and age at first recruitment (Lr = 13.00cm, tr = 2.4years). Results portrayed slow and isometric growth, median life-span and high survival of a continuously recruited spawning stock of Pagruscaeruleostictus. Also, the stock suffered growth overfishing, moderate fishing pressure and overexploition, implying the need for management to recalibrate measures for rational exploitation. Res. Agric., Livest. Fish.7(3): 517-531,  December 2020

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 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, mortality and stock assessment of greenback mullet, Planiliza subviridis from northwest Arabian Gulf, Iraq

2021 ◽  
Vol 6 (2) ◽  
pp. 142-148
Author(s):  
Abdul-Razak M. Mohamed ◽  
Ali H. Al-Hassani
Keyword(s):  
Mortality Rate ◽  
Stock Assessment ◽  
Population Analysis ◽  
Arabian Gulf ◽  
Total Mortality ◽  
Reference Points ◽  
Fishing Mortality ◽  
Fish Samples ◽  
Exploitation Rate ◽  
First Maturity

The growth, mortality and stock parameters of greenback mullet, Planiliza subviridis from Iraqi marine waters, northwest Arabian Gulf was assessed using FiSAT II software for length-frequency data collected from February 2020 to January 2021. P. subviridis is one of the species caught in large quantities as commercial by artisanal fishers. Fish samples were collected by the Shaheen steel-hulled dhow and from the artisanal fishermen. The total length and body weight relationship of fish was estimated as W= 0.034L2.670, indicating negative allometric growth. Of 3350 specimens, growth and mortality parameters were evaluated. The asymptotic length (L∞), growth rate (K) and growth performance index (Ø') were 33.8 cm, 0.30 and 2.535, respectively. The total mortality rate (Z), natural mortality rate (M), and fishing mortality rate (F) were 1.11, 0.74 and 0.38, respectively. The present exploitation rate (Epresent) of P. subviridis computed as 0.34. Length at first capture (L50) was 17.47 cm. Recruitment of P. subviridis was observed throughout the year, with a peak during July. The yield per recruit analysis indicates that the current exploitation rate was below the biological target reference points (E0.1 and Emax), which refers to the stock of P. subviridis is underexploited. Virtual population analysis results showed that mid-lengths (16-22 cm) experienced the highest fishing mortality. The length at first capture (L50) was higher than the length at first maturity (Lm) of the species. So, for management purposes, more yields could be obtained by increasing the fishing activities on this species for a substantial harvest.

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.

Movement, Growth and natural mortality rate of the Red Spot King Prawn, Penaeus longistylus Kubo, from the Great Barrier Reef Lagoon

1990 ◽  
Vol 41 (3) ◽  
pp. 399 ◽  
Author(s):  
MCL Dredge
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Great Barrier Reef ◽  
Annual Variation ◽  
Growth Parameters ◽  
Natural Mortality ◽  
Barrier Reef ◽  
Fishing Mortality ◽  
Nursery Areas ◽  
Reef Lagoon

Movement, growth and natural mortality rate of the red spot king prawn, Penaeus longistylus, occurring in waters of the Great Barrier Reef off Townsville, Queensland, were investigated in a series of tagging experiments. Adult P. longistylus did not migrate after leaving nursery areas. Their growth rate was slower than that of the conspecific species P. plebejus, and significant inter-annual variation in growth parameters was observed. The natural mortality rate, assessed by sequential tagging experiments that eliminated the possibility of confounding with the rate of fishing mortality, was estimated to be 0.072 (week-1).

scholarly journals First Assessment of the Thryssa vitrirostris (Engraulidae) Beach Seine Fishery in Northeastern Mozambique

J ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 116-132
Author(s):  
Bonifácio Manuessa ◽  
Eurico Morais ◽  
Teresa Cerveira Borges ◽  
Maria Teodósio ◽  
Francisco Leitão
Keyword(s):  
Standard Length ◽  
Growth Parameters ◽  
Mesh Size ◽  
Fishing Effort ◽  
Fishing Mortality ◽  
Beach Seine ◽  
Management Measures ◽  
Exploitation Rate ◽  
Exploitation Status ◽  
Sustainable Fishery

Monthly length-frequency data, from 2009 to 2014, was used to estimate the growth parameters, mortality, and spawning season, and to assess the exploitation status of Thryssa vitrirostris (Engraulidae) fisheries in Pebane. The von Bertalanffy asymptotic length (L∞) and growth rate (K) were 25.1 cm (standard length) and 0.41 per year (standard length), respectively. Two proxy recruitment peaks were found: the first peak of recruitment occurs from April to July, and the second recruitment peak from September to October. The total estimated mortality rates (Z), natural mortality (M), and fishing mortality (F) were Z = 1.31, M = 0.92, and F = 0.39. For the beach seine gear, the size at first catch of T. vitrirostris was Lc25 = 4.43 cm. The 50% retention size of the catch was Lc50 = 5.39 cm. The retention probability analyses revealed a large rate of juvenile fishing mortality (54.2%). The estimated exploitation rate (0.30) was below the maximum exploitation rate (0.48), and above the optimal sustainable exploitation rate (E50 = 0.28), evidencing a sustainable fishery. However, under such an exploitation regime, it is advised that a continuously monitoring-survey of T. vitrirostris is maintained. An increase in migration of fishermen has been recently recorded in Pebane, due to its rich fisheries, which can increase the fishing effort and the risk of overexploitation if management measures (such as mesh size increase) are not taken in advance.

scholarly journals Age, growth and mortality of the European Seabass, (Dicentrarchus Labrax) in Bardawil lagoon, North Sinai, Egypt

2021 ◽  
pp. 042-046
Author(s):  
El-Desoki Menna O ◽  
Younis Younis M ◽  
A Youssef El-Dakar ◽  
Ahmed Salem M ◽  
Ahmed Kassem S ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Age Groups ◽  
Dicentrarchus Labrax ◽  
Mortality Rates ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
European Seabass ◽  
Exploitation Rate ◽  
The Relationship ◽  
North Sinai

Age, growth, and mortality of European Seabass (Dicentrarchus labrax) were studied from a small-scaled fishery of Bardawil lagoon, (North Sinai, Egypt). 181 specimens (16.6 to 35 cm total Length and 39.8 to 367.2 g total weight). The relationship between length and weight was W = 0.0054L3.1428. Age was determined by otoliths and age groups I to IV years were observed. Growths in length and weight at the end of each year were calculated. The growth parameters of von Bertalanffy equation were calculated as (L∞ = 48.69 cm, K = 0.1677 yr -1 and t0 = -0.447 yr -1). Growth performance index was calculated (φ = 2.60 for length and 1.25 for weight). Mortality rates were 0.867 yr-1, 0.25 yr1and 0.617 yr-1 for total, natural and fishing mortality, respectively. The currently exploitation rate E = 0.712 yr-1 indicating that, the population of this species is being heavily exploited.

scholarly journals PARAMETER POPULASI IKAN BETOK (Anabas testudineus (BLOCH, 1792)) DI EKOSISTEM PAPARAN BANJIR SUNGAI MUSI, Lubuk Lampam

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Syarifah Nurdawati ◽  
Zulkarnaen Fahmi ◽  
Freddy Supriyadi
Keyword(s):  
Growth Parameters ◽  
Total Mortality ◽  
Fish Length ◽  
Fishing Mortality ◽  
Anabas Testudineus ◽  
Weight Growth ◽  
Exploitation Rate ◽  
Management Policies ◽  
Distribution Of Fish ◽  
Musi River

Anabas testudineus Bloch, 1792 is economically important fish species found in Lubuk Lampam floodplains of Musi River. Fishing activities that take place throughout the year can affect reproduction patterns and recruitment (new additions) of fish. This study aims to evaluate several parameters of betok fish populations that can be used as input for fish resource management policies in floodplains of Musi river. A total of 3271 samples of betok fish caught by fishermen from March to November 2011 were collected to obtain data on fish length and weight. Growth parameters (L∞, K, Z dan M) were calculated using FiSAT II based on the length frequency distribution of fish. The values of L∞ and K were obtained at 204.75 mm and 0.24 / year respectively while the maximum age of fish was estimated to be 4.36 years. The total mortality (Z) and natural mortality (M) of betok fish is 0.99 / year and 0.42 / year, Fishing mortality (0.56/year). The exploitation rate (0.57) was slightly lower than the predicted value (Emax= 0.69) indicating that Anabas  testudineus was near fully exploited in the Lubuk Lampam floodplain ecosystem.  

scholarly journals Population dynamics and the management of the Indo-Pacific king mackerel Scomberomorus guttatus from the upper Bay of Bengal off Bangladesh coast

1970 ◽  
Vol 27 (2) ◽  
pp. 82-90 ◽  
Author(s):  
H Rashid ◽  
MG Mustafa ◽  
S Dewan
Keyword(s):  
Bay Of Bengal ◽  
Sustainable Management ◽  
Growth Parameters ◽  
Fishing Mortality ◽  
Length Frequency ◽  
Growth Constant ◽  
Recruitment Pattern ◽  
Exploitation Rate ◽  
King Mackerel ◽  
Bangladesh Coast

Growth and mortality parameters, exploitation rates, annual recruitment patterns and length-weight relationships were estimated using FiSAT program from monthly length-frequency and weight samples of Indo-Pacific king mackerel, Scomberomorus guttatus, captured mainly by drift gill nets from the upper Bay of Bengal off Bangladesh coast. The aim was to estimate growth parameters, mortality rates, exploitation rate and recruitment pattern of S. guttatus for sustainable management. The von Bertalanffy growth parameters asymptotic length L∞ (cm) and growth constant K (per year) were 73.5 and 0.6, respectively. The L∞ and Z/K estimates provided by Wetherall plot were 73.3 and 2.3 cm. The annual rate of fishing mortality (F = 0.806) was low compared to the relatively high natural mortality (M = 0.994). The exploitation rate (E = 0.45) shows that the species was not over-exploited in the region. About 77.1% of S. guttatus were recruited during May-July and 23.0% during September-October. The growth performance index (φ′) was 3.5. The total length and body weight relationship was W = 0.0101 L 2.8622 suggesting that the growth rate was negative allometric (b<3). The growth parameters derived in the current study are comparable with previous estimates available for the same species. DOI: 10.3329/bvet.v27i2.7558 Bangl. vet. 2010. Vol. 27, No. 2, 82-90

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