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

scholarly journals Population Parameters of Two Commercially Important Species belonging to the Family Sciaenidae Encountered in the Coast of Ghana

2020 ◽  
pp. 21-29
Author(s):  
Samuel K. K. Amponsah ◽  
Selasi Yao Avornyo ◽  
Kofi Ferni Anyan
Keyword(s):  
Mortality Rate ◽  
Fish Species ◽  
Coastal Waters ◽  
Total Mortality ◽  
Population Parameters ◽  
Recruitment Pattern ◽  
Important Species ◽  
The Family ◽  
Exploitation Rate ◽  
Commercially Important

Population parameters for two commercially important fishes of Sciaenidae from the coastal waters of Ghana were assessed using length-frequency data obtained from August 2017 to June 2019. Samples of the assessed fish species were obtained through experimental fish trawl along the coast of Greater Accra, Ghana. Trawling was performed every quarter for an average of one hour at an average speed of 3.0 km/hr. In all, a total of 399 samples were measured and the obtained data were analyzed with FiSAT II. The assessed fish species included Pteroscion peli (165 samples) and Pseudotolithus senegalensis (234 samples). The asymptotic length (L∞) was 19.4 cm and 41.5 cm forPteroscion peli and Pseudotolithus senegalensis. Pteroscion peli and Pseudotolithus senegalensis recorded growth rate (K) of 0.48 and 0.50 per year respectively. Both assessed fish species exhibited continuous recruitment pattern with minor and major recruitment peaks. The total mortality rate (Z) was 1.86 and 1.63 per year for Pteroscion peli and Pseudotolithus senegalensis. The fishing mortality rate (F) was estimated at 0.66 and 0.63 per year for Pteroscion peli and Pseudotolithus senegalensis. The natural mortality rate (M) estimated for Pteroscion peli and Pseudotolithus senegalensis was 1.20 and 1.00 per year respectively. The exploitation rate (E) of Pseudotolithus senegalensis (0.39) and Pteroscion peli (0.36) respectively was far below the maximum exploitation rate (Emax), indicating under-exploitation of its fishery in the coastal waters of Ghana, hence the need to enhance the exploitation of these species.

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 PENDEKATAN POLA PEREMAJAAN DAN LAJU EKSPLOITASI IKAN LOUHAN UNTUK PENGENDALIAN IKAN ASING INVASIF DI DANAU MATANO, SULAWESI SELATAN

2018 ◽  
Vol 23 (4) ◽  
pp. 227
Author(s):  
Dimas Angga Hedianto ◽  
Hendra Satria
Keyword(s):  
Mortality Rate ◽  
Alien Species ◽  
Invasive Alien Species ◽  
Total Mortality ◽  
Growth Equation ◽  
Recruitment Pattern ◽  
Lake Matano ◽  
South Sulawesi ◽  
Exploitation Rate ◽  
Annual Total

Ikan louhan tergolong jenis ikan hibrid (sehingga tidak dapat ditentukan nama ilmiahnya) dari famili Cichlidae yang terindikasi sebagai ikan asing invasif di Danau Matano. Keberadaan ikan tersebut di Danau Matano perlu dikaji dan dikendalikan untuk menjaga kelestarian keanekaragaman hayati jenis ikan endemik. Penelitian ini bertujuan untuk menganalisis pola peremajaan dan laju eksploitasi ikan louhan sebagai pendekatan dalam pengendalian ikan asing invasif di Danau Matano, Sulawesi Selatan. Analisis data dilakukan terhadap 2.931 ekor ikan louhan yang ditangkap menggunakan jaring insang percobaan berbagai ukuran mata jaring dilengkapi data enumerator secara bulanan pada bulan Februari hingga November 2016 dengan bantuan perangkat lunak FiSAT II. Hasil analisis menunjukkan bahwa pola pertumbuhan ikan louhan di Danau Matano bersifat alometrik positif. Pertumbuhan mengikuti persamaan Lt=23,67[1-e0,41(t+0,4281)]. Umur maksimum (tmax) mencapai 7,32 tahun dengan performa pertumbuhan (Ø’) sebesar 2,36. Laju mortalitas total (Z) tahunan didapatkan sebesar 1,46 tahun-1. Laju mortalitas penangkapan tahunan (F = 0,38 tahun-1) lebih rendah daripada laju mortalitas alami tahunan (M = 1,08 tahun-1). Laju eksploitasi (E) ikan louhan di Danau Matano hanya sebesar 0,26 tahun-1 dimana menunjukkan bahwa upaya pemanfaatannya masih sangat rendah. Pola peremajaan terjadi dua kali dalam setahun, yaitu pada Mei (16,19%) dan Oktober (6,05%). Upaya pengendalian ikan louhan sebagai ikan invasif di Danau Matano perlu dilakukan pada saat puncak peremajaan tertinggi secara berkesinambungan disertai peningkatan laju eksploitasi e” 48% dari upaya yang ada, terutama pada April-Mei dan September-Oktober di daerah litoral perairan danau.Flowerhorn cichlid is classified as hybrid species (so that the scientific name can’t be determined) from Cichlidae which indicated as invasive alien fish in Lake Matano. The existence of flowerhorn in Lake Matano need to be assessed and controlled to preserve the biodiversity of endemic fish species. This research aims to assess recruitment pattern and utlization status of flowerhorn cichlid for controlling of invasive alien species at Lake Matano, South Sulawesi. Data analysis was carried out on 2,931 flowerhorn Cichlid caught using experimental gillnets of various mesh sizes included enumerators data which recorded monthly from February to November 2016 using FiSAT II software. The analysis resulted the growth pattern of flowerhorn cichlid in Matano louhan Lake was positive allometric. The growth equation of flowerhorn cichlid was Lt=23.67[1-e0,4(t+0.4281)]. Longevity (tmax) attained 7.32 years with growth performance (Ø’) was 2.36. The annual total mortality rate (Z) obtained 1.46 years-1. The annual fishing mortality rate (F = 0.38 years-1) is lower than the annual natural mortality rate (M = 1.08 years-1). Exploitation rate (E) of flowerhorn cichlid in Lake Matano only 0.26 years-1, which was indicated under exploitation. Recruitment pattern occurs twice a year, in May (16.19%) and October (6.05%). The eradication efforts to control population of flowerhorn cichlid as invasive alien species in Lake Matano needs to be done at the peak of recruitment and also increased exploitation rate about e” 48% of existing efforts, especially on April-May and September-October in the littoral area of Lake Matano.

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 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, 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 Some Aspect on the Biology of Pen Shell Atrina Pectinata (Linneaus, 1767) In Coastal Waters of Maqueda Bay, Philippines

2019 ◽  
Vol 2 (2) ◽  
Keyword(s):  
Coastal Waters ◽  
Total Mortality ◽  
Condition Index ◽  
Recruitment Pattern ◽  
Spawning Period ◽  
Growth Coefficient ◽  
Measurement And Analysis ◽  
Pen Shell ◽  
Atrina Pectinata

A Total of 379 pen shells Atrinapectinata were collected from February 2017 to January 2018 in the coastal waters of Maqueda Bay. Measurement and analysis of length and weight were done using FiSAT software. Population parameters were assessed to evaluate the stock status which includes the asymptotic length (L∞) and growth coefficient (K) to be 34.65 cm, 0.77 year−1 respectively. Specimens of A. pectinata reached a mean length of 20.98 cm. Length-weight relationship resulted to “negative allometric” 0.0462L2.6533 R2 = 0.7823; signifying pen shells growth was faster in length than on weight. The recruitment pattern was continuous over the year with one major peak during rainy season (July). In addition, the highest catch based on collected sampling date catch was during summer, which suggest as the peak season of the species in the area. Furthermore, the average catch annually of hookah diver was 17.69208. Higher condition index was recorded from April to May, September and January, indicating the high quality of pen shell meat and is recommended as the best period to harvest pen shell whereas June to August and October to December can be concluded as the spawning period of the pen shell and the ideal period to institute close season. Further analysis revealed that the pen shell was nearly facing overexploitation with the exploitation rate (E = 0.46) mainly due to lack of a minimum limit size and also due to an increase in the harvesting effort. The estimated total mortality (Z), natural mortality (M) and fishing mortality (F); 1.36 year−1, 1.01year−1 and 0.62 year−1, respectively. Using the mentioned (Z), (M), (F) and (E), the total population resulted to 84725.7 suggesting that half of the population has been exploited due to overfishing

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 parameters of the pontic shad, Alosa immaculata Bennett, 1835 in the Fatsa coast of the south-eastern Black Sea

2019 ◽  
Vol 36 (4) ◽  
pp. 319-324
Author(s):  
İsmet Balık
Keyword(s):  
Black Sea ◽  
Maximum Yield ◽  
Total Mortality ◽  
Reference Points ◽  
Growth Equation ◽  
Fishing Mortality ◽  
Population Parameters ◽  
The South ◽  
South Eastern ◽  
Exploitation Rate

The aim of this study is to estimate population parameters of pontic shad, Alosa immaculata Bennett, 1835 in the Fatsa coast of the south-eastern Black Sea. A total of 314 pontic shad specimens were collected from study area using artisanal fishing gears from March 2013 to February 2014. In the study, parameters of the von Bertalanffy growth equation were found as L∞=43.05 cm; k=0.430 per year and t0=-0.451 year. The growth performance index (Φ') was estimated as 2.90. The total mortality (Z), natural mortality (M), fishing mortality rates (F) were calculated as 1.33 year-1, 0.75 year-1 and 0.58 year-1, respectively. The annual instantaneous fishing mortality rate was greater than both the target (Fopt=0.375 year-1) and limit (Flimit=0.50 year-1) biological reference points. Similarly, the present level of exploitation rate (E=0.43) was higher than the exploitation ratio for maximum yield per recruit (Emax=0.375) suggesting that overexploitation occurred. These results showed that this species has been over-exploited in the Fatsa coast of the south-eastern Black Sea. Measures should be taken to reduce the current exploitation rate for sustainable fishing of pontic shad in the Fatsa coast of the south-eastern Black Sea.

Which community indicators can measure the impact of fishing? A review and proposals

2003 ◽  
Vol 60 (1) ◽  
pp. 86-99 ◽  
Author(s):  
Marie-Joëlle Rochet ◽  
Verena M Trenkel
Keyword(s):  
Average Length ◽  
Total Mortality ◽  
Diversity Indices ◽  
Reference Points ◽  
Size Spectra ◽  
Expected Effect ◽  
Piscivorous Fish ◽  
Exploitation Rate ◽  
Species Abundances ◽  
The Impact

Population and community descriptors that might be used as indicators of the impact of fishing are reviewed. The criteria used for the evaluation of these indicators are meaning, expected effect of fishing, exclusiveness to fishing effects, and measurability. Population indicators such as total mortality rate, exploitation rate, or average length are the most operational indicators because their meaning is clear and the expected effect of fishing on them is well understood so that reference points can be set. On the other hand, indicators based on the composition of species assemblages such as diversity indices and ordination of species abundances are difficult to interpret, and the effect of fishing on them is not easily predicted. Robust indicators describing the community functions of interest (production and transfer of biomass to large fish), such as size spectra descriptors or the proportion of piscivorous fish in the community, are more promising but are not yet well developed. New candidate indicators are proposed: the change in fishing mortality required to reverse population growth rate, the proportion of noncommercial species in the community, and the average length and weight in the community.

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