scholarly journals Population Dynamics, Fishery, and Exploitation Status of Norway Lobster (Nephrops norvegicus) in Eastern Mediterranean

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 289
Author(s):  
Alexios Lolas ◽  
Dimitris Vafidis
Keyword(s):  
Population Dynamics ◽  
Sexual Maturity ◽  
Eastern Mediterranean ◽  
Total Mortality ◽  
Probit Analysis ◽  
Maturity Stage ◽  
Nephrops Norvegicus ◽  
Norway Lobster ◽  
Exploitation Rate ◽  
Exploitation Status

Norway lobster (Nephrops norvegicus) is one of the most valuable shellfish resources in the Mediterranean and the northeast Atlantic. Sustainable management of its fishery require long-term scientific monitoring of its stocks. Population dynamics, fishery, and exploitation status of the Norway lobster were studied over a long time series (between 2008 and 2014) in a semi enclosed gulf in Easter Mediterranean (Pagasitikos Gulf). Sampling was carried out using a commercial bottom trawl with a codend mesh size of 28 mm in three different regions within the Gulf. Sex was identified macroscopically and all individuals were measured and weighed. Growth and Age groups were investigated by analysis of length–frequency distributions of the Carapace length (CL) for both sexes. Fishing, Natural and Total Mortality, along with Exploitation rate of the total stock were estimated by the FiSAT software package. Females were further examined and classified based on their maturity stage and the size at onset of sexual maturity was estimated by Probit analysis. Temporal differences in mean CL were detected for both sexes, with a tendency of lower values each year, along with a respective increase in Fishing Mortality and Exploitation Rate, indicating the effects of fishing pressure over the population. Size at onset of sexual maturity was estimated at 32.6 mm, higher than the official mesh sizes for creels (28 mm) and gillnets (26 mm). According to the analyses, the local Norway lobster stock is over-exploited, which should be taken under consideration by the regional policy makers.

scholarly journals Heterozygosity fitness correlations and generation interval of the Norway lobster in the Aegean Sea, eastern Mediterranean

2019 ◽  
Vol 26 (1) ◽  
Author(s):  
Georgios A. Gkafas ◽  
Marianthi Hatziioannou ◽  
Emmanouil E. Malandrakis ◽  
Costas S. Tsigenopoulos ◽  
Ioannis T. Karapanagiotidis ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Recruitment Strategy ◽  
Breeding Period ◽  
Nephrops Norvegicus ◽  
Norway Lobster ◽  
Genetic Impact ◽  
Potential Population ◽  
High Gene ◽  
Local Residents

Abstract Background Comprehensively detailed information on population dynamics for benthic species is crucial since potential admixture of individuals could shift the genetic subdivision and age structure during a full breeding period. The apparent genetic impact of the potential recruitment strategy of Norway lobster Nephrops norvegicus is still under research. For this reason the present study was focused on genetic variation of the species over a given continuous year period in a semi-enclosed gulf of the Aegean Sea. Results Analyses revealed that the relative smaller size class in females and the apparent faster growth of males may represent a key-role differential strategy for the two sexes, whereas females tend to mature slower. Heterozygosity fitness correlations (HFCs) showed substantially significant associations suggesting that inbreeding depression for females and outbreeding depression for males are the proximate fitness mechanisms, respectively. Conclusions Nephrops norvegicus uniformal genetic composition (background of high gene flow), could be attributed to potential population recolonization, due to a hypothesized passive larval movement from deeper waters, which may suggest that some offspring of local residents and potential male non-breeders from other regions admixture randomly.

Reproduction et dynamique de population de la barbotte brune Ictalurus nebulosus (Le Sueur) dans la frayère de la rivière aux Pins, fleuve Saint-Laurent, près de Montréal (Québec)

1982 ◽  
Vol 60 (1) ◽  
pp. 31-39
Author(s):  
Gilles Harvey ◽  
Rejean Fortin
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Sexual Maturity ◽  
Total Mortality ◽  
Northern Pike ◽  
Spawning Activity ◽  
Brown Bullhead ◽  
Ictalurus Nebulosus ◽  
Dynamique De Population ◽  
St Lawrence River

Two trap nets set in Rivière aux Pins, near its confluence with the St. Lawrence River, permitted the capture and subsequent marking or tagging of adult brown bullhead for the study of their reproductive biology and population dynamics. Spawning activity is examined in relation to water temperature and water level which, in 1976 and 1977, was controlled by means of a log weir, in order to enhance northern pike reproductive success. The study of sex ratio, sexual maturity, gonadosomatic ratio, and fecundity served to characterize the Rivière aux Pins bullhead spawning population. The results of the captures, markings, taggings, and recaptures led to the evaluation of total mortality, several aspects of exploitation by sport fishing, movements, population density, biomass, production, and yield.

scholarly journals PARAMETER POPULASI DAN BIOLOGI REPRODUKSI IKAN BENTONG (Selar crumenophthalmus) DI PERAIRAN KWANDANG,GORONTALO UTARA

2015 ◽  
Vol 6 (2) ◽  
pp. 111 ◽  
Author(s):  
Ria Faizah ◽  
Lilis Sadiyah ◽  
Tuti Hariati
Keyword(s):  
Total Mortality ◽  
Maturity Stage ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Frequency Data ◽  
Population Parameters ◽  
Length Frequency ◽  
Exploitation Rate ◽  
Length Frequency Data ◽  
Pelagic Fisheries

Perairan Kwandang merupakan salah satu basis utama perikanan pelagis kecil di perairan laut Sulawesi. Salah satu jenis yang banyak dimanfaatkan adalah ikan bentong (Selar crumenophthalmus). Penelitian ini bertujuan untukmenduga parameter populasi, tingkat pemanfaatan (E), dan biologi reproduksi dari ikan bentong. Data panjang cagak dikumpulkan dari PP Kwandang dari bulan Januari hingga November 2012. Pendugaan parameter populasi dilakukan dengan menggunakan metode Bhattacharya dengan bantuan software FISAT II Hasil analisis menunjukkan bahwa laju pertumbuhan (K) sebesar 0,76 per tahun dengan L”=24,7 cm. Laju kematian total (Z) sebesar 2,63 per tahun, dengan laju kematian alamiah (M) sebesar 1,28 per tahun, laju kematian akibat penangkapan (F) sebesar 1,3 per tahun dan laju pemanfaatan 0,51. Tingkat pemanfaatan ikan bentong sudah relatif optimum. Rasio jenis kelamin ikan bentong jantan dan betina adalah 1: 1,02. TKGI paling banyak ditemukan. Musim pemijahan ikan bentong diduga terjadi pada bulan November dan Desember.The Kwandang waters is one of the main base for small pelagic fisheries in Sulawesi sea. Bigeye scad (Selar crumenophthalmus) is one of species from small pelagic is exploited. The objectives of the research was to estimate the population parameters, exploitation rate and reproductive biology of bigeye scad. Length frequency data were collected from PP Kwandang, from January November 2012. Estimation of population parameters of bigeye scad used FISAT II method. The results showed that growth rate as follows (K) = 0,76 year-1 , L”=24,7 cm. Total mortality rate (Z) = 2,63 year-1, with natural mortality (M) = 1, year-1 and fishing mortality (F) = 1,3 year-1 and exploitation rate (E)=0,51. The exploitation rate are already optimum. Sex ratio of male and female are 1:1,02. The most commonly founded is Gonado Maturity Stage of I. The spawning season of bigeye scad estimated was November and December

scholarly journals DINAMIKA POPULASI DAN STATUS PEMANFAATAN UDANG TIGER (Penaeus monodon Fabricius 1798) DI PERAIRAN TARAKAN, KALIMANTAN UTARA

2020 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Umi Chodrijah ◽  
Ria Faizah ◽  
Tirta Danu
Keyword(s):  
Growth Parameters ◽  
Penaeus Monodon ◽  
Total Mortality ◽  
Optimal Level ◽  
Survey Method ◽  
Von Bertalanffy ◽  
Population Parameters ◽  
Exploitation Rate ◽  
Tiger Prawn ◽  
Exploitation Status

Udang tiger (Penaeus monodon Fabricius 1798) di Tarakan merupakan salah satu komoditas ekspor dan sudah dimanfaatkan cukup lama serta memiliki permintaan dan nilai ekonomis yang tinggi. Penelitian dinamika populasi dan status pemanfaatan udang tiger di perairan Tarakan dan sekitarnya dilakukan untuk mengevaluasi status stok sumberdaya udang agar pengelolaannya dapat berkelanjutan. Penelitian ini dilakukan pada bulan Januari-November 2016 dengan metode survey. Status pemanfaatan diduga berdasarkan laju eksploitasi dan estimasi rasio pemijahan berbasis data panjang (LB-SPR). Hasil pengamatan menunjukkan udang tiger memiliki panjang karapas asimptotik (CL∞) sebesar 65,45 mm, laju pertumbuhan (K) sebesar 1,55 /tahun dan nilai t0 sebesar -0,20/tahun sehingga diperoleh persamaan pertumbuhan Von Bertalanffy CLt = 65,45(1 – e-1,55(t+-0,20)). Laju mortalitas total (Z) sebesar 6,56/ tahun, mortalitas alami (M) sebesar 1,95/tahun, mortalitas penangkapan (F) sebesar 4,62/tahun dan tingkat pemanfaatan (E) sebesar 0,70 /tahun. Tingkat pemanfaatan udang tiger di perairan Tarakan lebih besar dari tingkat pemanfaatan optimal sehingga disarankan untuk menurunkan upaya sebesar 40% dari upaya saat ini.Tiger prawn (Penaeus monodon Fabricius 1798) was one of the export commodity and had been exploited for longtime ago so it was necessary to study about its population parameters and exploitation status for its sustainable management. This research aimed to study about the population parameters and exploitation status of tiger prawn. The research were carried out from January to November 2016 using survey method and the enumeration programme. The growth parameters were based on the Modal Progression Analysis. Exploitation status was estimated based on length based spawning potential ratio (LB-SPR). The results showed that the asymptotic length (CL∞) was 65.45 mm, the growth rate (K) was 1.55 /year and = t0 was -0,20/year so Von Bertalanffy Growth Model was CLt = 65.45(1 - e -1.55(t+-0.20)). Total mortality (Z) was 6.56/years, natural mortality was 1.95/years and fishing mortality was 4.62/years and the highest recruitment of tiger prawns occured in May. The exploitation rate (E) was 0,70/years. The exploitation rate now is higher then the optimal level so it is recommended to reduce 40% of the current efforts.

scholarly journals BIOLOGY AND POPULATION DYNAMICS OF BANANA SHRIMP (Penaeus merguiensis) IN THE TARAKAN WATERS, EAST BORNEO

2013 ◽  
Vol 19 (2) ◽  
pp. 99 ◽  
Author(s):  
Duranta D. Kembaren ◽  
Ali Suman
Keyword(s):  
Population Dynamics ◽  
Mortality Rate ◽  
Total Mortality ◽  
Population Data ◽  
Fishing Effort ◽  
Growth Coefficient ◽  
Exploitation Rate ◽  
First Maturity ◽  
Dynamic Population ◽  
Penaeus Merguiensis

Study of biology and population dynamic of banana shrimp (<em>Penaeus merguiensis</em>) in Tarakan waters, East Borneo was carried out from January to November 2012. The aim of this research was to identify the biological aspects and population dynamics of banana shrimp. For estimating dynamic population, data were analysed using FiSAT II. The result showed that length at first capture (Lc) of banana shrimp by mini trawl (pukat hela) was 35 mm and the size at first maturity (Lm) was 33,86 mm in carapace length. Spawning occured all year around and reached it’s peak in March. The growth coefficient (K) of banana shrimp was 1,45/year with carapace asymptotic length (CL”) of 80 mm. Total mortality rate (Z) and natural mortality rate (M) were 4,85/year and 1,76/year. While fishing mortality rate (F) and exploitation rate (E) were 3,09/year and 0,64, respectively. The exploitation rate of banana shrimp in Tarakan waters tended to be overexploited so that it needed to be managed wisely and carefully by reducing the fishing effort and fishing season especially on spawning season. The recruitment peak of banana shrimp occured in May.

scholarly journals Population Dynamics of Five Important Commercial Fish Species in the Sundarbans Ecosystem of Bangladesh

2019 ◽  
pp. 1-13
Author(s):  
Md. Golam Mustafa ◽  
Imran Ahmed ◽  
Mohammod Ilyas
Keyword(s):  
Population Dynamics ◽  
Fish Species ◽  
Total Mortality ◽  
Assessment Tools ◽  
Natural Mortality ◽  
Lates Calcarifer ◽  
Recruitment Pattern ◽  
Exploitation Rate ◽  
Acanthopagrus Latus ◽  
The Sundarbans

Aims: To determine the population dynamics and assess the exploitation level of Mystus gulio, Acanthopagrus latus, Chelon parsia, Otolithoides pama and Lates calcarifer in the Sundarbans ecosystem of Bangladesh. Study Design: Monthly length-frequency data of five fish species were collected from the Sundarbans ecosystem. The lengths of five fish species were recorded to the nearest one cm intervals in each month. Place and Duration of Study: The study was conducted from January to December 2011 in the Sundarbans ecosystem in Bangladesh. Methodology: The FAO-ICLARM Fish Stock Assessment Tools (FiSAT II) software was used to estimate the von Bertalanffy growth parameters (L∝ and K), mortality coefficients (Z, M and F), probability of capture, recruitment pattern and Yield/Biomass-per-recruit for five commercially important fish species caught by fishers in the Sundarbans ecosystem of Bangladesh. Results: In the Sundarbans ecosystem of Bangladesh area the values of asymptotic length (L∝) for Mystus gulio, Acanthopagrus latus, Chelon parsia, Otolithoides pama and Lates calcarifer were found to be 23.0 cm, 33.6 cm, 30.0 cm, 32.5 cm and 55.0 cm respectively while the growth co-efficient (K) were 0.75, 0.85, 1.1, 0.8 and 0.5 respectively. The estimates for L∝ (23.00 – 55.0 cm) and K (0.5-1.1 year-1) obtained were consistent with those available in the literature. Relatively high K and low L∝ values, typical of short-lived tropical fishes, were obtained for Mystus gulio, Acanthopagrus latus, Chelon parsia and Otolithoides pama. The length growth performance index (ϕ’) of the Pauly and Munro’s function was in the range of 2.599 – 3.180. Natural mortality, fishing mortality and total mortality were in the range of 0.956-1.89, 0.55-1.58 and 1.52-3.3 respectively. Estimates for total mortality (Z) and natural mortality (M) imply low annual rates of survival and high turnover rates. The recruitment pattern suggested one main pulse of annual recruitment. The exploitation rate was estimated to be between 27% and 47% and the length at first capture was estimated to be approximately 19-54% of L∝. The exploitation rate obtained for five fish species are relatively lower compared to other available studies in the coastal areas of Bangladesh. The growth and exploitation rates obtained were compared with available estimates to evaluate the consistency of the results with current knowledge about the species in the region. Conclusion: The study indicated that the length-at-first-capture/L∝ seem to be a simple parameter, which could be used to make a rapid assessment of the status of the stocks. All together, the present study reveals that the population of these five studied species attains acceptable sustainability levels in the Sundarbans ecosystem and scope for a slight increase in catch efforts.

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.

Population dynamics of Atlantic seabob Xiphopenaeus kroyeri (Decapoda: Penaeidae) off the state of Sergipe, north-eastern Brazil

2017 ◽  
Vol 99 (1) ◽  
pp. 143-153 ◽  
Author(s):  
Josafá José Do Carmo Reis ◽  
Kátia Meirelles Felizola Freire ◽  
Leonardo Cruz Da Rosa ◽  
Thaíza Maria Rezende Da Rocha Barreto ◽  
Daniel Pauly
Keyword(s):  
Population Dynamics ◽  
Carapace Length ◽  
Atlantic Coast ◽  
Total Mortality ◽  
Live Weight ◽  
Sampling Bias ◽  
Growth Function ◽  
Western Atlantic ◽  
Xiphopenaeus Kroyeri ◽  
Exploitation Status

The aim of this study was to analyse the population dynamics of Xiphopenaeus kroyeri in Sergipe, Brazil. Four samples were collected monthly from shrimp trawlers based in the municipality of Pirambu from March 2015 to May 2016. Carapace length (CL), total length (TC), live weight (LW), sex and maturity stages were obtained for each specimen. A total of 13,035 individuals were analysed with an overall sex ratio of 1:1. However, this ratio favoured females in larger sizes, which reflects a reproductive strategy, as their larger size allows for larger gonads, higher fertility and production of more eggs. An inflexion point was observed in the relationship between total and carapace length, probably related to reproduction, as this occurred after first maturity. A reproduction peak was observed in August–September, which does not correspond to the closed season. The parameters estimated for a seasonally oscillating version of the von Bertalanffy growth function were CL∞ = 33 mm and K = 1.5 year−1 for females, and CL∞ = 31 mm and K = 1.7 year−1 for males (C = 0.6 and WP = 0.8 for both sexes). These estimates do not support the latitudinal rule in terms of larger sizes in higher latitudes, which may be associated to methodological differences, occurrence of more than one species along the South-western Atlantic coast, sampling bias, exploitation status and unbalanced availability of studies. The instantaneous total mortality rate was high and should be further investigated to allow for the definition of the exploitation status of seabobs in Sergipe.

scholarly journals Aspects of Population Dynamics of Tiger Tooth Croaker, Otolithes ruber (Bloch and Schneider, 1801) from Northwest Arabian Gulf, Iraq

2021 ◽  
pp. 9-21
Author(s):  
Abdul-Razak M. Mohamed ◽  
Ali H. Al-Hassani
Keyword(s):  
Population Dynamics ◽  
Population Analysis ◽  
Arabian Gulf ◽  
Relative Yield ◽  
Total Mortality ◽  
Reference Points ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
Exploitation Rate ◽  
Otolithes Ruber

The present study consists of the growth, mortality, relative yield recruit and virtual population analysis of tigertooth croaker, Otolithes ruber from Iraqi marine waters, northwest Arabian Gulf between February 2020 and January 2021. Analysis of population dynamics employed methods fitted in FiSAT II software using pooled length-frequencies. A total of 3835 individuals of O. ruber ranged from 17.0 to 60.0 cm have been collected. The exponent (b) of the length-weight relationship was found to be 2.755. The von Bertalanffy growth parameters (L∞ and K) were estimated as 68.5 cm and 0.36, respectively, while the growth performance index (Ø') was 3.228.  The total mortality (Z) was calculated as 1.10, while the natural and fishing mortality rates were 0.69 and 0.41, respectively, and the current exploitation rate (Ecurrent) was 0.38. Fish were recruited to the fishery at a mean size of L50= 20.55 cm. The recruitment pattern of O. ruber was continuous throughout the year with two major peaks. The analysis of yield-per-recruit (Y/R’) indicates that the current exploitation rate was below the biological target reference points (E0.1 = 0.40 and Emax= 0.53), refer to the stock of O. ruber is underexploited. The 27 cm length group was more vulnerable to fishing and more harvested according to virtual population analysis. sLength at first capture was higher than the length at first maturity of the species in the region. For management purposes, more yields could be obtained by increasing the mesh sizes of the nets employed in the fishing of the species. 

Sign in / Sign up

Export Citation Format

Share Document