Estimation of growth parameters and mortality rates of kingfish (Scomberomorus commerson) in the north of Persian Gulf (Khuzestan Province)

Length composition data from monthly catches of Scomberomorus commerson landed in Choebdeh and Hendijan fish landing places in Khuzestan Province, north Persian Gulf, were collected from 2004 to 2005. We used the data to estimate growth parameters and mortality coefficients of the fish. Response surface analysis produced by the ELEFAN program provided a complete set of Von Bertalanffy growth parameters estimation. We found L infinity =120cm (fork length), K=0.49per year and t_0=-0.11 year for the fish. The length-weight relationship was estimated as W=0.022tL ^2.7575 with r^2=0.978S. Based on the calculated b, we conclude that the fish has an isometric growth pattern. The total, natural and fishing mortality coefficients were estimated as, Z=1.58, M=0.58 and F=1.0, respectively. Exploitation ratio (E) for this species was estimated as 0.63 per year. The E-value indicates that the kingfish in this part of the Persian Gulf has been overexploited. Current fishing pattern in the Khuzestan province shows that 97.07% of the cumulative length frequency and 78.18% of the cumulative weight frequency of the landed fish are under standard size. Results of this study indicate that exploitation of kingfish does not follow an optimum trend and if this trend continues, the stock of Scomberomorus commerson in this area will be threatened

Estimating growth parameters for Otolithes ruber in waters of Bushehr, Hormozgan and Sistan and Baluchestan Province, Southern Iran

Using length frequency of the Otolithes ruber collected in waters of three southern province of Iran, we estimated the fish growth parameters and monthly measured fork length of around 1000 fish caught using gill net with a mesh size of 6.5 centimeters in waters of this study area. The length infinity (L∞) in Bushehr, Hormozgan and Sistan and Baluchistan province was estimated as 58.5, 56, 59.5 centimeters, growth coefficient per year (K) as 0.48, 043, 0.32 and age at zero length (to) as -0.006, -0.002, -0.001 respectively. The relationship between length and weight of the fish in the three provinces determined. The parameters q, b and r (correlation coefficient) were 0.173, 2.868, 0.984 for Bushehr, 0.012, 2.962, 0.932 for Hormozgan and 0.056, 2.604, 0.921 for Sistan and Baluchestan province. We also evaluated the average length for the fish caught in different months and landing places. An ANOVA test showed a significant difference (P≤0.05) between the average lengths of the fish caught in different months

Age, growth and length at first maturity of Otolithes ruber in the northwestern part of the Persian Gulf, based on age estimation using otolith

Estimates of age, growth parameters, length-weight relationship and length and age at first maturity of the otolithes ruber are required for fishery management. We used counting annuli on the section of sagittal otoliths to age O.ruber from the Northwest Persian Gulf in south of Iran. Estimated ages ranged from 0 to 6 years, and maximum frequency of fishes was observed in age-group 1. The values of growth parameters L∞, k and to were calculated by von Bertalanffy model and the results were 67.57 (cm), 0.27 (year-1) and -0.43 respectively. Parameters b and an in length-weight relationship were calculated 3.19 and 0.005 respectively. Length and age at first maturity were estimated 28 cm and 1.55 year

Estimation growth parameters of Parastromateus niger in the coastal waters of Sistan and Baluchestan, Oman Sea

Using length frequency information collected for Parastromateus niger catch in the coastal waters of Sistan and Baluchestan, Oman Sea, we estimated growth parameters of the fish. The data were collected of the fork length of around 887 fish each month during 2001. The length infinity (L∞), growth coefficient (K) and the length at age zero (t0) of the fish measured as 57.8 cm, 0.3 per year and -0.003 respectively. The relationship between the length and weight of the fish was estimated as 0.0469 for “a” , 2.829 for "b" and 0.914 for the correlation coefficient. The average length of the fish in different months of the year calculated and a Tukey test showed that this was significantly different

Growth, mortality and spawning season of the spangled emperor (Lethrinus nebulosus Forsskal, 1775) in coastal waters of Hormozgan Province in the Persian Gulf and Oman Sea

The population parameters and spawning season of the Spangled emperor (Lethrinus nebulosus) were studied in coastal waters of Hormozgan province. The monthly calculated mean values of gonadosomatic index (GSI) of females were indicate to increase from February, reach the highest in March and decline in June. The spawning season peak of L. nebulosus occurred in March. The Von Bertalanffy growth parameters, L∞, K and t0 were estimated as, 67.2cm, 0.16.year^-1 and -1.161 year, respectively. The relationship between weight and length (Fork Length) can be expressed as W=0.051 L^2.722, which indicates that Spangled Emperor has negative allometric growth. Using length converted catch curve, total mortality (Z) was estimated as 1.13 year^-1 and natural mortality was estimated using Pauly's equation, as 0.57 per year. Finally, the fishing mortality (F) was 0.56, which gives an exploitation rate (E) of 0.50

Growth parameters and mortality rates of Liza klunzingeri in the Iranian waters of the Persian Gulf and Oman Sea, using Length Frequency Data

The aim of the present study was to investigate the population dynamics of Liza klunzingeri, in Hormouzgan province waters located in northern coasts of the Persian Gulf and Oman Sea. This study was carried out from October 2007 to September 2008. Samples were collected from commercial stake traps. The relationship between weight and fork length was found to be W= 0.0214 F.L^2.8233 suggesting that Liza klunzingeri shows isometric growth. Length-based stock assessment using the FiSAT software package showed an asymptotic length (L∞) of 20.3cm FL and growth coefficient of 0.6.yr^-1. These results gave a growth performance index (ø) of 2.39. The total mortality coefficient was estimated to be 2.31, a natural mortality of 1.09 and fishing mortality of 1.22. The estimated total mortality which, in relative terms, is considered average (2.31.yr^-1), coupled with the currently observed exploitation rate of 0.52 for L. klunzingeri, estimated from the mortality rates, suggested that the species is moderately exploited

Population dynamics of the Spanish mackerel (Scomberomorus commerson) in coastal waters of Oman Sea

Length composition data of narrow-barred Spanish mackerel, Scomberomorus commerson (Lacepede 1800), landed between April 2002 to March 2004, were monthly used to estimate the growth, mortality and exploitation parameters of the stock. Maximum fork length and weight were 170 cm and 38 kg, respectively. Nonlinear least square fitting provided a complete set of von Bertalanffy growth estimates: L¥=178 cm (FL); K=0.28 and to= -0.36 years. The estimated value of total mortality based on length converted catch curve using these growth parameters is Z=0.95 year-I. Natural mortality based on growth parameters and mean environmental temperature (T=26.5°C) is M=0.36 year-1. Furthermore, the annual instantaneous fishing mortality rate of 0.59 year-1 was by far in excess of the precautionary target (Fopt=0.18 year-1) and limit (Flimit=0.24 year-1) biological reference points, indicating that the resource is heavily over-exploited and the management of this species should be implanted rapidly if they are to remain sustainable

Catch length structure, mortality and exploitation of Otolithes Ruber during the ten-year period (2000-2010) in the northwest of Persian Gulf

In the present study, length structure, mortality and exploitation rate of Otolithes ruber during a ten-year period were studied. Sampling was carried out by using bottom trawl net in the fishing area in Northwest of Persian Gulf over 1 year study period. Length data was also collected from fisheries research institute and fishery organization. Age determination was done by reading annual rings on sectioned otolith. Growth parameters were calculated based on age and length data. These data were used to estimate natural mortality rate. Total mortality was obtained from the age curve. Logarithmic catch and natural mortality were calculated from Pauly's equation. The averages of length in the last ten years were 35 to 39 cm. The samples ranged in length from 12 to 58 cm with the maximum frequencies between 28-44 cm. Length distribution was normal in this study. The maximum catch was composed of fish in the 40 to 48 cm length range with an average age of 2 to 3 years. The average total mortality, natural mortality and fishing mortality were 0.98, 0.56, and 0.42 respectively. Mortality was higher in age group 0 and age group 1, but mortality of the other age groups dramatically decreased. Exploitation rate in the last ten years were 0.42 indicating a near complete exploitation. Based on the results a more effective exploitation strategy is suggested in this region

The reproductive biology and feeding habits of yellow fin seabream, Acanthopagrus latus (Houttuyn, 1782), in the northern Persian Gulf

Monthly samples of Acanthopagrus latus (Houttuyn, 1782) were used to determine (1) feeding habits and (2) reproduction characteristics of the species in relation to its size, spawning season and sex in the northern part of the Persian Gulf from January to December 2013. The smaller length classes of all samples were dominated by male fish. All gonads examined, were ovotestis during the spawning period from February till May. Male and female ovotestes were dimorphic in structure which represented a transitional stage in a protandrous sex change. Length at first sexual maturity of female A. latus was 24.40 cm. A. latus fed predominantly on bivalves, gastropods, cephalopods, stomatopods, fish and decapods which showed changes according to the season and body size. According to our results, it appears that A. latus feeds throughout the year; the highest value of gastrosomatic index (GaSI) for both sexes was recorded in February, which was significantly different from that in other months. The results of this study also indicate that feeding in yellowfin seabream is very intense before reproduction (during January and February). It decreases gradually after February to June during the spawning season

Status of the tiger tooth croaker, Otolithes ruber (Schneider, 1801) and jinga shrimp, Metapenaeus affinis(H. Milne Edwards, 1837) stocks in Khouzestan coastal waters

Population dynamics parameters and exploitation ratio of Jinga Shrimp, Metapenaeus affinis were studied from Sep 2011 to Dec 2011 and data collected from two landing places (Hendijan and Lifee-Bosif). During the project, more than 2200 specimens of jinga shrimp were measured. The mean value of length for the male and female were calculated as 9.8±0.86, 10.24±1.18 and mean value of weight for the male and female was as 6.730±1.64, 8.14±2.90 respectively. The length-weight relation were calculated as TW=0.024TL2.24 (n=1084,R^2=0.71) for males, TW=0.011TL2.80 (n=1081,R^2= 0.81) for females also we found significant different level length-weight relation in P<0.05. The growth parameters of von Bertalanffy equation were as, L_∞: 14.73 and K: 1.1 and t0: -0.02. The estimated valve of total mortality, natural mortality, fishing mortality and exploitation ratio is Z: 4.35, M: 1.68, F: 2.67, E: 0.61 respectively. By using method analyses knife-edge selection, relative yield per recruitment (Y'/R) :0.014, relative biomass per recruitment, (B'/R) :0.085., Exploitation ratio maximum sustainable yield, Emax : 0.38; biological reference points for Jinga Shrimp stock was calculated. MSY and fmsy value was 600T and 46100day respectively. Result in this study showed exploitation ratio Jinga Shrimp stock is over fishing and decreases exploitation ratio proposed