scholarly journals Growth, Mortality and Exploitation Rates of African Moonfish (Selene dorsalis, Gill 1863) Encountered in the Coast of Ghana (West Africa)

2021 ◽  
Vol 2 (2) ◽  
pp. 6-10
Author(s):  
Samuel K. K. Amponsah ◽  
Berchie Asiedu ◽  
Selasi Yao Avornyo ◽  
Seyramsarah Blossom Setufe ◽  
Pierre Failler
Keyword(s):  
Mortality Rate ◽  
West Africa ◽  
Growth Parameters ◽  
Total Mortality ◽  
Mesh Size ◽  
Optimum Level ◽  
Management Measures ◽  
Simulating Annealing ◽  
Exploitation Rate ◽  
Length Frequency Data

Growth, mortality and exploitation rate of Selene dorsalis (Gill, 1863) from the continental shelf of Ghana (West Africa) were examined between July 2018 and June 2019. The study provided results on fishery dynamics parameters needed to estimate the stock status and characteristics of S. dorsalis in the coast of Ghana. Monthly length-frequency data were collected from 629 samples and analysed using fisheries models fitted in TropFishR package in R software. The von Bertalanffy growth parameters were utilised to analyse the population dynamics of the species using ELEFAN Simulating Annealing. Based on the estimates, the asymptotic total length (L∞) was 22.2 cm, the coefficient of growth (K) was 0.76 year-1, and the calculated growth performance index (phi) was 2.58 with Rn value of 0.55. The total mortality rate (Z) was 3.32 year-1 with a natural mortality rate (M) of 1.21 year-1 and fishing mortality rate (F) of 2.11 year-1. The exploitation rate (E) estimated for the species was above the optimum level of 0.5, which indicates that S. dorsalis is overexploited in the coast of Ghana. It can be concluded that the exploitation rate of S. dorsalis has exceeded the optimum limit, hence the need for enforcement and improvement of fisheries management measures such as mesh size regulations, capping of canoes, closed fishing seasons and compliance with fisheries policies.

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 Population dynamics of Mormyrus rume (Valenciennes, 1847; Osteoglossiformes; Mormyridae) Of Ikere-Gorge, Iseyin, Oyo State, Nigeria

2020 ◽  
Vol 19 (1) ◽  
pp. 51-57
Author(s):  
Stephen O. Ajagbe ◽  
Folashade. F. Ojo-fakuade
Keyword(s):  
Growth Parameters ◽  
Management Strategies ◽  
Total Mortality ◽  
Mesh Size ◽  
Fish Population ◽  
Population Parameters ◽  
Growth Coefficient ◽  
Exploitation Rate ◽  
Length Frequency Data ◽  
Mormyrus Rume

The structure of a fish population is determined by the equilibrium between growth, recruitment and total mortality. But, there is paucity of information on the growth and mortality of Mormyrus rume in Nigeria. Therefore this study is needful to determine its population parameters, with a view of evolving management strategies for its sustainable exploitation. Estimates of population parameters of Mormyrus rume were obtained from length-frequency data of 836 individuals collected monthly for a period of 24 months from January 2017 to December 2018. The estimated growth parameters were: asymptotic length (L∞) was 100.8cm; growth coefficient (K) was 0.62/year; growth performance (Ɵ) was 3.8; length at maturity (Lm) was 52.57cm; reproductive load (Lm/L∞) was 0.52 and optimum length (Lopt) was 65.10cm. Likewise, natural, fishing and total mortalities were 0.93, 1.46 and 2.39 respectively. The values of exploitation rate (0.61) and ratio of total mortality and growth coefficient (3.85) showed that Mormyrus rume is most exploited in Ikere-gorge. Therefore, appropriate fishing regulations should be enforced to regulate fishing gears and mesh size that will fish Mormyrus rume at sustainable level. Keywords: Recruitment, mortality, growth, exploitation, length

scholarly journals PARAMETER POPULASI DAN TINGKAT PENGUSAHAAN RAJUNGAN (Portunus pelagicus) DI PERAIRAN ASAHAN, SELAT MALAKA

2017 ◽  
Vol 9 (2) ◽  
pp. 93
Author(s):  
Andina Ramadhani Putri Pane ◽  
Heri Widiyastuti ◽  
Ali Suman
Keyword(s):  
Mortality Rate ◽  
Carapace Width ◽  
Total Mortality ◽  
Optimum Level ◽  
Market Demand ◽  
Swimming Crab ◽  
Portunus Pelagicus ◽  
Monthly Data ◽  
Management Measures ◽  
Exploitation Rate

Tingginya permintaan pasar terhadap rajungan mengakibatkan aktivitas penangkapannya berlangsung secara intensif. Selat Malaka merupakan salah satu daerah penangkapan rajungan yang penting di Indonesia. Tujuan penelitian ini adalah untuk mengestimasi parameter populasi dan tingkat eksploitasi rajungan (Portunus pelagicus) di perairan Asahan dan sekitarnya. Pengumpulan data bulanan dilakukan pada bulan Juni 2015 sampai dengan Nopember 2016. Hasil penelitian menunjukkan bahwa musim penangkapan berlangsung sepanjang tahun dengan puncak pada bulan Juli dan Oktober, puncak pemijahan terjadi pada bulan Januari dan Agustus. Ukuran lebar karapas pertama kali tertangkap dengan gillnet (Lc) dan ukuran pertama kali matang gonad (Lm) masing-masing sebesar 109,6 mm dan 104,1 mm. Laju pertumbuhan (K) sebesar 1,38/tahun dan lebar karapas asimtotik (L) sebesar 183,10 mm. Laju kematian total (Z) rajungan sebagai 4,31 per tahun, laju kematian karena penangkapan (F) dan laju kematian alami (M) masing-masing 2,96 per tahun dan 1,35 per tahun; laju eksploitasi (E) diestimasi sebesar 0,69. Tingkat pemanfaatan rajungan di perairan Asahan diduga telah melewati optimal, sehingga perlu dilakukan pengelolaan melalui pengurangan jumlah unit gillnet rajungan sebanyak 38% dari kondisi saat ini. Blue swimming crab faced intensive fishing pressure due to the high market demand. The Malacca Strait is one of important fishing area for blue swimming crab. The research aims to estimate the population parameters and exploitation rate of blue swimming crab (Portunus pelagicus) in the Asahan and adjacent waters. A monthly data were collected from June 2015 to November 2016 that caught by Gillnet. The results showed that the fishing season takes place throughout the year with peaks in July and October, meanwhile peak of spawning season in January and August. The carapace width at first capture (Lc) and first mature (Lm) were 109.6 mm and 104.1 mm, respectively. The growth rate (K) was 1.38 / year and the asymptotic length (L) was 183.10 mm. Total mortality rate (Z) was 4.31 per year, fishing mortality rate (F) and natural mortality rate (M) were 2.96 per year and 1.35 per year respectively; Exploitation rate (E) was estimated at 0.69. It means that the exploitation rate of swimming crab in the Asahan waters found exceed the optimum level, therefore the management measures needs to reduce effort (unit) of gillnet by a 38% of actual level. 

scholarly journals Growth, Mortality, and Exploitation Rate of Penaeus merguensis in the North Coast of Central Java, Indonesia

2019 ◽  
Vol 23 (4) ◽  
pp. 207
Author(s):  
Suradi Wijaya Saputra ◽  
Anhar Solichin ◽  
Wiwiet Teguh Taufani
Keyword(s):  
Mortality Rate ◽  
Population Biology ◽  
Carapace Length ◽  
Growth Parameters ◽  
Total Mortality ◽  
Survey Method ◽  
North Coast ◽  
Optimum Level ◽  
Central Java ◽  
Exploitation Rate

One of the most-caught shrimp in north coast of Central Java is Penaeus merguiensis. However, little is known on the population biology of the organisms. This study was aimed to investigate length-weight relationship, growth, length at first capture (Lc50), mortality rate, and exploitation rate of P. merguiensis in Western part of Central Java’s northern coastal waters. The study was conducted from May 2016 to July 2017 using survey method. Samples were taken for 15 times (month) from 9 coastal fishing ports. The result shows that the relationship of the carapace length and weight is negative allometry. The growth parameters of CL∞ and K were 52.5mm and 1.3 y-1 (male) and 57.25mm and 1.2 y-1 (female). Total mortality rate (Z), natural mortality rate (M), and fishing mortality rate (F) were 4.51 y-1, 1.86 y-1 and 2.65 y-1 (male), and 5.36 y-1, 1.72 y-1, and 3.64 y-1 (female), respectively. The exploitation rate (E) of male banana shrimp was 0.59, and for female shrimp was 0.68. The result shows that the exploitation level has exceeded the optimum level (E>0.5). Recruitment of P. merguiensis may occur the whole year, but it peaks were in March and August (male), April and August (female). Carapace length of first captured (CLc50) was 20.63mm (male) and 18.28mm (female). It means that the sized of captured P. merguiensis is less than the size of first mature (CLm50) or growth overfishing and as a result, disrupting the availability of adult shrimp. The condition occurs due to the size of cod-end mesh measured 0.75inc.

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 Population dynamics of Sardinella aurita (Val., 1847) within Ghana’s coastal waters

2017 ◽  
Vol 4 (3) ◽  
pp. 237-248
Author(s):  
Samuel KK Amponsah ◽  
Patrick K Ofori Danson ◽  
Francis KE Nunoo ◽  
Godfred A Ameyaw
Keyword(s):  
Mortality Rate ◽  
Coastal Waters ◽  
Total Mortality ◽  
Mesh Size ◽  
Reference Points ◽  
Recruitment Pattern ◽  
Commercial Fish ◽  
Management Interventions ◽  
Exploitation Rate ◽  
Sardinella Aurita

Following the declining stocks of Sardinella aurita within the coastal waters of Ghana, this study aimed at examining some population parameters of Sardinella aurita as a guide for managing this important stock sustainably. Length-frequency data of 717 samples were obtained from June, 2014 to January 2015 and measured for total length with the resultant data analyzed using FiSAT II. The asymptotic length (L∞) and growth rate (K) were 21.53 cm SL and 0.25yr-1 respectively. The theoretical age at birth (t0), longevity (tmax) and growth performance index (ϕ) were -0.74yr-1, 12 years and 1.849 respectively. Total mortality rate (Z), natural mortality rate (M) and fishing mortality rate (F) were 3.17, 0.76 and 2.41yr-1 respectively. The ages at first recruitment and first capture signaled future collapse of the stock, in the absence of proper management interventions. VPA outcome showed that mid- lengths of 11 cm and 12 cm SL experienced the highest harvesting rate with MSY estimated at 7733 tons. The recruitment pattern was continuous with two major recruitment pulses. Exploitation rate (Ecurr=0.76) was higher than the maximum exploitation rate (Emax=0.56), indicating unsustainable exploitation. Further, the fishing regime fell within the overfished stage based on the Quadrant Rule. For sustainable exploitation of this commercial fish species, implementation of relevant biological reference points through reduction in fishing efforts, creation of marine protected areas and mesh size regulation are urgently advocated.Res. Agric. Livest. Fish.4(3): 237-248, December 2017

Life history traits of the exploited limpet Patella candei (Mollusca: Patellogastropoda) of the north-eastern Atlantic

2011 ◽  
Vol 92 (6) ◽  
pp. 1379-1387 ◽  
Author(s):  
P. Henriques ◽  
R. Sousa ◽  
A.R. Pinto ◽  
J. Delgado ◽  
G. Faria ◽  
...  
Keyword(s):  
Life History ◽  
Mortality Rate ◽  
Sexual Maturity ◽  
Life History Traits ◽  
Growth Parameters ◽  
Total Mortality ◽  
Recruitment Pattern ◽  
Length Relationship ◽  
North Eastern ◽  
Exploitation Rate

Life history traits of Patella candei were studied for the first time, including weight versus length relationship, growth, age structure, sexual maturity, recruitment pattern, mortality rates and yield and biomass-per-recruit of an exploited population in Madeira Island, north-eastern Atlantic using monthly length–frequency data from January to December 1999. The growth pattern of P. candei showed positive allometric nature of growth (b > 3, P < 0.05). The estimated growth parameters showed an asymptotic length (L∞) and growth coefficient (K) estimated at 80.81 mm and K at 0.32 year−1 with a growth performance index (φ′) calculated as 3.32 based on the collected data. This species is moderately long-lived reaching up to 9.36 years and achieving sexual maturity at 36.7 mm of shell length. The recruitment pattern was continuous, displaying a major peak event per year, occurring in January (25.12%). The estimated total mortality rate (Z) was 1.79 year−1 while natural mortality rate (M) was 0.55 year−1 and fishing mortality rate (F) was 1.24 year−1. The probability of capture shows that the length at first capture (Lc) was 42.7 mm, the exploitation rate (E) 0.693 and the maximum allowable limit of exploitation (Emax) was 0.779 for the highest yield. The exploitation rate was less than the predicted Emax values, showing that the stock of P. candei was found to be under-exploited in the investigated area; however, its slow growth and long life make it extremely vulnerable to over-exploitation.

scholarly journals Population dynamics of Chrysichthys nigrodigitatus (Lacépède, 1803) in Ikere-gorge, Oyo State, Nigeria

2021 ◽  
Vol 56 (1) ◽  
pp. 79-86
Author(s):  
S.O. Ajagbe ◽  
D.O. Odulate ◽  
R.O. Ajagbe ◽  
O.S. Ariwoola ◽  
F.I. Abdulazeez ◽  
...  
Keyword(s):  
Assessment Tool ◽  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Fishing Mortality ◽  
Length Frequency ◽  
Optimum Length ◽  
Growth Coefficient ◽  
Exploitation Rate ◽  
Length Frequency Data

The growth and mortality parameters of Chrysichthys nigrodigitatus were estimated to assess the sustainability of its exploitation in Ikere-gorge, Oyo State, Nigeria. A total of 1210 of Chrys­ichthys nigrodigitatus were sampled from fishermen catches between January, 2017 and Decem­ber, 2018. C. nigrodigitatus were exploited with gillnet, cast net and traps (Malian trap net and bamboo). Total lengths were measured with fish measuring board. The FAO-ICLARM Stock Assessment Tool (FiSAT II) software was used to analyze length-frequency data of the fish. The estimated growth parameters are: asymptotic length is 60.9 cm, growth coefficient is 0.96, optimum length is 38.51 cm; length at maturity is 33.44 cm while length-at-first-capture is 12.62 cm. The estimated mortality parameters are: total mortality is 3.29 per year, natural mortality is 1.43 per year and fishing mortality is 1.86. It was observed that C. nigrodigitatus of Ikere-gorge were more vulnerable to exploitation at sizes less than their length at maturity. Likewise, the ex­ploitation rate (E = 0.57 yr-1) is greater than sustainable exploitation rate (Emax = 0.46 yr-1). This shows that exploitation of C. nigrodigitatus in Ikere-gorge is not sustainable. Therefore, there is need to reduce fishing pressure on C. nigrodigitatus to ensure its sustainability in Ikere-gorge.

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

Growth, mortality, ovarian maturity, and exploitation of the Guinea shrimp, Holthuispenaeopsis atlantica (Balss, 1914) (Decapoda: Dendrobranchiata: Penaeidae) in inshore waters of Ghana, West Africa

2020 ◽  
Vol 40 (3) ◽  
pp. 247-255
Author(s):  
Paulina Okpei ◽  
Joseph Aggrey-Fynn ◽  
Isaac Okyere
Keyword(s):  
West Africa ◽  
Growth Parameters ◽  
Total Mortality ◽  
Growth Function ◽  
Frequency Data ◽  
Length Frequency ◽  
Inshore Waters ◽  
The Mean ◽  
Ovarian Maturity ◽  
Length Frequency Data

Abstract The Guinea shrimp, Holthuispenaeopsis (= Parapenaeopsis) atlantica (Balss, 1914) is exploited by traditional and commercial fisheries in the Gulf of Guinea, West Africa. We assessed growth, mortality, ovarian maturity, and exploitation of the population of the species in inshore waters of Ghana as a contribution of filling the knowledge gap on the species. Samples were obtained from fish landing sites from three different coastal towns in Ghana from October, 2017 to May, 2018. Length-frequency data were used to estimate growth, mortality and exploitation ratio. The modal class for males was 6.0–6.9 cm total length (TL) and 9.0–9.9 cm TL in females. The length and weight relationship established that growth in both sexes was negatively allometric. The estimated growth parameters from the length frequency data fitted with the von Bertalanffy growth function were asymptotic length (L∞) of 10.08 cm for males and 15.4 cm for females. The growth constant (K) was calculated as 0.99 yr–1 for males and 0.89 yr–1 for females. The mean length-at-first capture (Lc) was found to be lower than the mean length at sexual maturity (Lm). The sex ratio showed a preponderance of females over males throughout the period, with 76.21% females. The total mortality rate (Z) for males was more than for females. The estimated natural mortality was 2.32 yr−1 for males and 1.93 yr−1 for females (M) whiles fishing mortality (F) rate was 1.22 yr−1 for males and 1.46 yr−1 for females. The exploitation ratio showed the stocks were not over-exploited. The estimated population parameters of the species obtained should be significant for the sustainable management of this resource.

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