scholarly journals Population dynamics and management of two cichlid species in the Shatt Al-Arab River, Iraq

2020 ◽  
Vol 12 (2) ◽  
pp. 261-269
Author(s):  
Abdul-Razak M. Mohamed ◽  
Abdullah N. Abood
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Reference Points ◽  
Invasive Fish ◽  
Oreochromis Aureus ◽  
Cichlid Species ◽  
Assessment Study ◽  
Biological Target ◽  
Yield Per Recruit

Cichlids are invasive fish to Iraqi waters and became well established and prevailing in different waters. Despite that, there is no stock assessment study conducted for these fish. So, growth, mortality, recruitment and yield-per-recruit of two cichlid’s species; Coptodon zillii and Oreochromis aureus from the Shatt Al-Arab River, Iraq were evaluated from November 2015 to October 2016 using the FiSAT software. A total of 1285 C. zillii (2.9-24.0 cm TL) and 1353 O. aureus (4.5-25.0 cm TL) were examined. Length-weight relationships were derived, indicating allometric growth for both species. The growth parameters (L?, K, Rn, to and ?) obtained for C. zillii were 25.5 cm, 0.320, 0.212, -0.793 and 2.318, respectively, while for O. aureus were 27.8, 0.490, 0.214, -0.271 and 2.578, respectively. The annual rate of total mortality (Z), fishing (F) and natural (M) for C. zillii was found to be 1.51, 0.84 and 0.68 respectively, and for O. aureus 2.49, 1.08 and 1.41, respectively. The present exploitation rates (Epresent) for C. zillii and O. aureus were computed to be 0.454 and 0.57, respectively. Lengths at first capture (LC) were 12.97 cm for C. zillii and 13.25 cm for O. aureus. The peaks of recruitment of C. zillii and O. aureus were from February to May and May to July, respectively. The Epresent for C. zillii and O. aureus were below the biological target reference points (F0.1  and Fmax), indicating that these species were not overexploited. For management purposes, more yields could be obtained by an increase in the fishing activities on cichlids.

scholarly journals Population Dynamics and Management of Invasive Blue Tilapia (Oreochromis aureus) in Garmat Ali River, Basrah, Iraq

2020 ◽  
pp. 44-54
Author(s):  
Abdul-Razak M. Mohamed ◽  
Ayat N. Salman
Keyword(s):  
Population Dynamics ◽  
Growth Parameters ◽  
Relative Yield ◽  
Total Mortality ◽  
Reference Points ◽  
Recruitment Pattern ◽  
Oreochromis Aureus ◽  
Biological Target ◽  
Blue Tilapia ◽  
Yield Per Recruit

The blue tilapia, Oreochromis aureus is an invasive species that has successfully established itself in most of the Iraqi waters. However, there is little information on the population dynamics of the species in these waters. Hence, the growth parameters, mortality rates, probability of capture, recruitment pattern and yield per recruit of blue tilapia in Garmat Ali River, Iraq was assessed using FiSAT II software. A total of 1664 blue tilapia fish were collected by different fishing gears from October 2019 to September 2020 for recording the relevant data. The length-weight relationship obtained was W=0.0147*L3.0748 for fish ranging from 7.5 to 26.3 cm total length suggesting that the species shows positive allometric growth. The asymptotic length (L∞), growth constant (K), theoretical age at zero-length (t0), growth performance index (Ø') and longevity (tmax) were 29.9 cm, 0.205, -1.293, 2.345 and 10.7 years, respectively. The total mortality (Z), natural (M), fishing (F) and exploitation (E) were 1.09, 0.61, 0.48 and 0.43, respectively. Length at first capture (L50) was found to be 13.92 cm. The main recruitment pulse was from March to July with a peak in April, which account for 18.4% of the total recruitment in the year. The relative yield per recruit analysis revealed that the present exploitation rate (Epresent) for blue tilapia was below than the biological target reference points (E0.1 and Emax), which denotes that this stock was not over-exploited. For management purposes, higher yields can be achieved by reducing the mesh sizes of the nets during fishing.

scholarly journals Growth, Mortality and Yield-per-recruit of Nile Tilapia (Oreochromis niloticusM/em>) in Garmat Ali River, Iraq

2020 ◽  
Vol 8 (6) ◽  
Author(s):  
Ayat N. Salman ◽  
Abdul-Razak M Mohamed
Keyword(s):  
Assessment Tool ◽  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Reference Points ◽  
Fishing Mortality ◽  
Exploitation Rate ◽  
Biological Target ◽  
Mean Size ◽  
Yield Per Recruit

The study was conducted to estimate the growth, mortality, recruitment and yield-per-recruit of Oreochromis niloticus from Garmat Ali River, Basrah, Iraq from October 2019 to September 2020. The population parameters were analyzed using the FAO-ICLARM stock assessment tool (FiSAT). A total of 2696 O. niloticus ranged from 7.0 to 25.0 cm and the sizes 13.0-18.0 cm constituted 64.2% of the total catch. The length-weight relationship was W= 0.012L3.109 suggesting that the species shows positive allometric growth. The growth parameters for the species were estimated as L∞= 30.45 cm, K= 0.45, to= -0.313 and Ǿ= 2.622. The coefficients of total mortality (Z), natural mortality (M) and fishing mortality (F) were 3.26, 1.03 and 2.24, respectively. The exploitation rate for the species computed to be 0.69. Fish were recruited to the fishery at a mean size of L50= 14.92 cm. The peak of recruitment was 23.51% in June. The analysis of yield-per-recruit (Y/R’) indicates that stock is not being overfished since the present exploitation rate was below the biological target reference points (E0.1 and Emax). So, more yields could be achieved by reducing the mesh sizes of the nets for fishing the species

An Assessment of the Stocks of the Banana Prawn Penaeus merguiensis in the Gulf of Carpentaria

1979 ◽  
Vol 30 (5) ◽  
pp. 639 ◽  
Author(s):  
C Lucas ◽  
G Kirkwood ◽  
I Somers
Keyword(s):  
Carapace Length ◽  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Mortality Data ◽  
Optimal Size ◽  
Natural Mortality ◽  
Commercial Fishery ◽  
Significant Movement ◽  
Yield Per Recruit

A stock assessment of P. merguiensis in the Gulf of Carpentaria was made by means of a yield per recruit analysis based on studies of migration, growth and mortality. Data were collected both from the commercial fishery and tag recapture experiments. No significant movement of tagged prawns out of the fishing grounds occurred during the fishing season. Estimates of the von Bertalanffy growth parameters (L∞ = 38.0 mm carapace length, K = 0.08 week-1) were obtained from the change in monthly size distribution of commercial catches. The natural mortality coefficient (M) was 0.05 week-1 while the total mortality coefficient (Z) estimates for fishing seasons during 1974-1976, ranged from 0.22 week-1 to 0.35 week-1. The corresponding estimates of the optimal size at first capture ranged from 30.6 to 32.6 mm carapace length. Despite the high rates of exploitation (E = 0.78-0.86), there was no evidence to suggest that recruitment had been adversely affected.

Population dynamics and stock assessment of deep water rose shrimp Parapenaeus longirostris (Lucas, 1846) from the Mediterranean Coast of Morocco

2020 ◽  
Vol 67 (2) ◽  
Author(s):  
Hesham Awadh ◽  
Mustapha Aksissou
Keyword(s):  
Population Dynamics ◽  
Deep Water ◽  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Mediterranean Coast ◽  
Parapenaeus Longirostris ◽  
Exploitation Rate ◽  
The Mediterranean ◽  
Yield Per Recruit

The population dynamics and stock parameters of the deep water rose shrimp Parapenaeus longirostris (Lucas, 1846) was investigated from the Mediterranean coast of Morocco. Length-frequency data were collected from landings of coastal trawlers at M’diq Port on the Moroccan Mediterranean coast over a period of 13 months from April 2017 to April 2018. The estimated growth parameters were CL∞ = 52.87 mm, K = 0.39 yr-1 and to = - 0.35 .Total mortality coefficient (Z) was estimated as 3.49 yr-1 while the natural mortality estimated using two different methods was 1.89 yr-1 and 1.36 yr-1 and correspondingly the fishing mortality was calculated as 1.51 yr-1 and 2.13 yr-1. Yield per recruit and relative biomass per recruit analysis showed that the value of current exploitation rate (E) is 0.68 which is higher than the exploitation rate E 0.5=0.36, which indicates that the stock is currently overexploited. Hence it is advised to decrease the present exploitation rate by 50% of the current level to sustain the fishery.

Population dynamics and stock assessment of Hilsa shad, Tenualosa ilisha (Hamilton, 1822) along the coast of Bangladesh

2021 ◽  
Vol 48 (2) ◽  
pp. 231-241
Author(s):  
Md Khairul Islam ◽  
Md Humayun ◽  
Manmatha Nath Sarker ◽  
Md Sharifuddin ◽  
M Niamul Naser
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Population Analysis ◽  
Total Mortality ◽  
Maximum Sustainable Yield ◽  
Fishing Mortality ◽  
Recruitment Pattern ◽  
Weight Relationship ◽  
Tenualosa Ilisha ◽  
Highly Correlated

Stock Assessment of Tenualosa ilisha (Hamilton, 1822) were estimated using FiSAT-II software with length-frequency data collected from different landing centers. The Southeast Coast of Bay Of Bengal, Cox's Bazar. The Von Bertalanffy growth parameters Land K for the species were asymptotic length (L∞) was 51.41 cm, growth rate (K) was 0.75 year-1 and t0 = -0.2 year respectively. The estimated value of total mortality (Z) based on length converted catch curve using these growth parameters was 2.35 year-1.Natural mortality (M) based on growth parameters and mean environmental temperature (T = 27° C) was 1.00 year-1 and fishing mortality (F) was 1.35 year-1. Optimum length of hilsa at first capture (Lc=L50) was 28.36 cm TL. Growth performance indices (ϕ') was 3.30. The estimated value of the exploitation rate (E) using the length-converted catch curve was 0.57. The recruitment pattern of this species was continuous and two peaks per year. The present investigation clearly showed the over fishing (E > 0.50) condition for T. ilisha in Bangladesh. The estimated length-weight relationship for the combined sex was found to be W = 0.0109 L3. Virtual population analysis (VPA) showed that the maximum fishing mortality occurring in the length between 30 to 35 cm with a maximum value in the length of 32 cm that repeatedly indicate high fishing mortality in the T. ilisha. The generalized length-weight relationship was fitted with the pooled data of all monthly samples were BW = 0.029 TL2.718 (R2= 0.833) respectively. The results revealed that all length-weight relationships were highly correlated (r > 0.993). Maximum sustainable yield (MSY) was estimated as 435,554 t. Bangladesh J. Zool. 48(2): 231-241, 2020

scholarly journals Stock dynamics of the brushtooth lizardfish Saurida undosquamis (Richardson, 1848) from a tropical multispecies fishery in the southeastern Arabian Sea

2019 ◽  
Vol 32 ◽  
pp. 9
Author(s):  
Theparambil Mohamed Najmudeen ◽  
Pallangattu Kochukandan Seetha ◽  
Payiyappanal Ulahannan Zacharia
Keyword(s):  
Arabian Sea ◽  
Growth Parameters ◽  
Total Mortality ◽  
Fishing Effort ◽  
Reference Points ◽  
Trophic Levels ◽  
Southeastern Arabian Sea ◽  
Eastern Arabian Sea ◽  
The Mean ◽  
First Maturity

The brushtooth lizardfish Saurida undosquamis (Richardson, 1848) is a high trophic level benthic predator and is one among the most exploited demersal finfish species from eastern Arabian Sea by Indian trawlers. However, in recent years, the landings of many top predator fishes including S. undosquamis showed a declining trend resulting in a steady decline in the mean trophic levels of the fishes caught commercially in the region. We investigated the growth, mortality and stock dynamics of S. undosquamis harvested by mechanised trawls in the southeastern Arabian Sea, using length-based methods for the data collected during 2012–2016. Besides, Bayesian state-space implementation of the Schaefer model (BSM) and catch-based MSY (CMSY) estimation were also made using the data for the period 1985–2016. Total length of the fish ranged from 5.5 to 34.5 cm with average annual mean length of 22.0 cm during 2012–2016. The growth parameters L∞ and K were 37.3 cm and 0.41 year−1, respectively. The natural, fishing and total mortality coefficients were 0.92, 2.58 and 3.5, respectively and exploitation ratio was 0.82. The length at first maturity was estimated at 21.4 cm for females. The mean size in the catch is lower than the optimum length for exploitation. Fisheries reference points (MSY, Fmsy, Bmsy) as well as relative stock size (B/Bmsy) and exploitation (F/Fmsy) estimated from catch data and broad priors for resilience (r), implies an exploitation of 30% below Bmsy level. Results from the length-based Thompson and Bell prediction model indicates that reducing the present level of fishing effort by 40% would lead to a harvest of the species at a sustainable level. As “fishing down food web” is reported in recent years from eastern Arabian Sea, the exploitation of top predators need to be maintained at sustainable levels to prevent ecosystem changes along the region.

scholarly journals Population Dynamics of Reba Carp Cirrhinus Reba From Indus River, Sukkur, Sindh, Pakistan

2020 ◽  
Vol 48 (1) ◽  
pp. 81-91
Author(s):  
Khadim Hussain Memon ◽  
Rashida Bhanbhro ◽  
Qun Liu ◽  
Tahira Jabeen Ursani ◽  
Abdul Manan Shaikh ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Average Length ◽  
Minimum Weight ◽  
Total Mortality ◽  
Reference Points ◽  
Minimum Length ◽  
Average Weight ◽  
Fishing Mortality ◽  
Indus River ◽  
Strategic Plans

Present work was done from Indus River, Sukkur, Sindh, Pakistan to evaluate the present stock of Cirrhinus reba Suhni (Reba carp) for first time. Since the assessment of stocks deliver the important knowledge of stocks of commercially important fish species to the fisheries managers to make better strategic plans for sustainable exploitation. Data based on length-frequency was obtained from October 2015 to March 2016, a total of 463 pairs of length-weight were measured. Minimum length was measured to 13cm, maximum length was 29cm and the average length of 17cm was measured with minimum weight of 15g, maximum weight of224g and67g was the average weight. Obtained results of length-weight relationship were R2 = 0.817, a = 0.037 and b = 2.557. Growth parameters were computed as L∞= 29.40 cm and= 0.240 year-1using ELEFAN method in FISAT computer package. Growth performance index (∅′) was calculated as ∅′ = 2.317 year-1 Total mortality Z, natural mortality M and fishing mortality F was estimated as= 0.630 year-1, M= 0.617 year-1 and F=0.012 year-1 respectively. Using (E = F/Z) the exploitation ratio was obtained as E=0.019 year-1 Current fishing mortality rate of 0.012 was smaller than the target biological reference points (Fopt) of M (0.617). While MSY was recorded as; 8.144 tonsyear-1 which showed the higher results than 0.031 tons year-1ofcurrent catch. This study concluded that the C. reba confronting poor health though the stocks found not to be overexploited in the region. Bangladesh J. Zool. 48(1): 81-91, 2020

Estimating some population parameters and stock assessment of Dark Sleeper Odontobutis potamophila in the Gaosha River, Wuyuan County, Jiangxi Province, China

2017 ◽  
Author(s):  
Wu Bin Wang Haihua ◽  
Fu Huiyun Zhang Yanping
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Landing Site ◽  
Jiangxi Province ◽  
Recruitment Pattern ◽  
Growth Coefficient ◽  
West Part ◽  
Exploitation Rate ◽  
Odontobutis Potamophila

A study was conducted to investigate the growth parameters, mortality and recruitment pattern of Odontobutis potamophila collected in the Gaosha river fish landing site, west part of Wuyuan County (Latitude: 29° 14' 29" N, Longitude: 117° 45' 49" E). O.potamophila were collected from November, 2013 to October, 2014. Growth parameters, asymptotic length (L) = 192mm and growth coefficient (k) = 0.22 year-1. Growth performance index(Ø’) =3.91, total mortality (Z) = 0.72 year-1, natural mortality (M) = 0.32 year-1, fishing mortality (F) = 0.40 year-1 and exploitation rate (E) = 0.55year-1.The estimated exploitation rate (E) has slightly exceeded the optimum value of E indicating this species was sustainable exploitation in the study area. The exploitation ratios were computed as Emax= 0.61, E10= 0.52, E50= 0.34. The length at first capture at 50%, (Lc) was 77 mm. The recruitment pattern of the species was found continuous all-round the year with one peak. The observation of the annual recruitment of O.potamophila found to occur from May to July. Steady biomass also increased with length class until 121-125 mm, and the total steady state biomass was found to be 2240 kg.

scholarly journals Stock Assessment of Lates niloticus in Upper Victoria Nile and its Impact on Uganda’s Economy

2021 ◽  
Vol 19 (2) ◽  
pp. 11-26
Author(s):  
Samuel Bassa ◽  
Albert Getabu ◽  
Erick Ogello ◽  
Anthony Taabu Munyaho ◽  
Dickson Oteino Owiti ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Nile Perch ◽  
Lates Niloticus ◽  
Slot Size ◽  
Catch Rates ◽  
A Minor

This study investigated the growth, mortality, recruitment, and catch estimates of Nile perch, Lates niloticus (Linnaeus, 1758), in Upper Victoria Nile, basing on total catches and length-frequency data collected between 2008 and 2018. The asymptotic length (L∞) had a value of 93.45 cm TL, growth curvature (K) was 0.446 year-1, total mortality (Z) was 1.85year-1, natural mortality (M) was 0.79 year-1, fishing mortality (F) was 1.09 year-1, exploitation rate (E) was 0.59 and growth performance index(ᴓ) of (L∞) was 3.604. There were two peaks recruitment period, a minor one in March and a major one in August. These respectively accounted for 12.8 and 26.3 percent of the total catch. The optimum sustainable yield (E0.5), maximum sustainable yield (Emax) and, economic yield (E0.1) was 0.278, 0.421 and 0.355 respectively. The findings suggest that there is a decline in the population of Lates niloticus in Upper Victoria Nile. Therefore, strict management of the fishery by adhering to the recommended slot size of 50-85 cm TL and curtailing use of illegal gears is needed. This will be possible through enforcement of regulations, monitoring, control and surveillance in order to ensure sustainability of the Nile perch fishery and ecosystem restoration in the Upper VictoriaNile.Keywords: Lates niloticus; Catch rates; Growth parameters, Upper Victoria Nile.

Estimation of Population Parameters and Stock Assessment of Mastacembelus armatus in the Taojiang River, Xinfeng County, Jiangxi Province, China

2019 ◽  
Author(s):  
Wu Bin ◽  
Wang Haihua ◽  
Ma Benhe ◽  
Xu Xiandong ◽  
Zeng Qingxiang
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Total Mortality ◽  
Landing Site ◽  
Jiangxi Province ◽  
Recruitment Pattern ◽  
Growth Coefficient ◽  
Exploitation Rate ◽  
Mastacembelus Armatus ◽  
River Fish

A study was conducted to investigate the growth parameters, mortality and recruitment pattern of Mastacembelus armatus collected in the Taojiang River fish landing site, Xinfeng County. M. armatus were collected from March, 2018 to February, 2019. Growth parameters, asymptotic length (L¥) = 58.8cm and growth coefficient (k) = 0.13 year-1. Growth performance index(Ø2 ) =2.65, total mortality (Z) = 0.75 year-1, natural mortality (M) = 0.32 year-1, fishing mortality (F) = 0.43 year-1 and exploitation rate (E) = 0.57year-1.The estimated exploitation rate (E) has slightly exceeded the optimum value of E indicating this species was over exploited mainly due to fishing in the study area. The exploitation ratios were computed as Emax= 0.59, E10= 0.45, E50= 0.31. The length at first capture at 50%, (Lc) was 19.51 cm. The Steady biomass also increased with length class until 36.0-36.9 cm and the total steady state biomass was found to be 19.12 tons.

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