Iranian Journal of Fisheries Sciences 17(4) 776-789 2018 DOI: 10.22092/ijfs.2018.116992 Population assessment and yield per recruit of longtail tuna (Thunnus tonggol) in Northern of the Persian Gulf and Oman Sea (Iran, Hormozgan Province)
Darvishi M.1; Paighambari S.Y.1*; Ghorbani A.R.1; Kaymaram F.2
Received: September 2016 Accepted: November 2016
Abstract The purpose of this study was to find some important biological aspects of Thunnus tonggol in coastal waters of Hormozgan Province (Persian Gulf and Oman Sea). A total monthly data of 4383 individuals ranging from 25 to 124 cm fork length were collected from April 2015 to March 2016. The data were analyzed with FiSAT II software using the ELEFAN1 package to estimate the population parameters. The length-weight relationship was TW=0.00002 FL2.87 (R2=0.97) showing an isometric growth for T. tonggol. Growth parameters were computed as L∞=129.6 cm, K=0.39 year-1 and t0=−0.28 with the growth performance index, φ’ of 8.7. The total mortality (Z) was estimated 1.58 year-1 using catch curve method. The natural (M) and fishing mortality (Fcurr) were obtained 0.49 and 1.09 year-1, respectively. The exploitation ratio was 0.69. Length at first capture (Lc) was estimated as 60.2 cm fork length. The yield per recruit (Y/R) maximized in maximum fishing mortality rate 0.85 year-1. The biomass per recruit decreased to 17.2% of unexploited biomass (virgin biomass) at Fcurr. The current fishing mortality exceeds optimum fishing mortality (Fopt) and limit fishing mortality (Flimit) as biological reference points. The results indicated that population of T. tonggol is overexploited in the Persian Gulf and Oman Sea and there no further scope for improving the exploitation of this species.
Keywords: Thunnus tonggol, Longtail tuna, Population dynamics, Persian Gulf, Oman Sea
1-Gorgan University of Agricultural Sciences and Natural Resources. 2-Iranian Fisheries Science Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran *Corresponding author's Email: [email protected]
777 Darvishi et al., Population assessment and yield per recruit of longtail tuna (Thunnus tonggol) in…
Introduction with the highest catches ever recorded Assessing the status of the stocks of around 170,000 t, landed in 2014. Over neritic tuna species in the Indian Ocean the past decade, Thailand, Indonesia, is fairly challenging due to the lack of Malaysia and Iran mostly contributed to available data (IOTC, 2015). The the global landings. However, it is family Scombridae, mackerels and important to note that catch statistics tunas, includes 15 genera with 49 are underestimates due to a high species which some of them are the incidence of underreporting of longtail most important species in commercial catches in underdeveloped countries, fisheries (Randall, 1995). Seven species especially where the species is targeted of tuna and mackerels were recorded as in artisanal fisheries (Griffiths, 2010). commercial fisheries from the Persian Scombrids accounts for about 40% of Gulf and Oman Sea namely Auxix the total catch in Hormozgan Province thazard, Euthynnus affinis, Katsuwonus (in South of Iran) and Thunnus tonggol pelamis, Scomberomorus commerson, represent the major volume of this S. guttattus, Thunnus albacares and T. province fishery and its management tonggol. depends on the provision of described In recently years (2006–2015), information on population assessment. Scombridae represented an average It seems that the distribution of 39% of the total catch in the Persian longtail tuna in the Persian Gulf and Gulf and Oman Sea (Iranian waters). In Oman Sea is associated with the study area Scombrids are usually temperature of surface water. In Iran, caught by surface gillnets (93%) and longtail tuna are targeted by traditional purse-seine (5%) during their migration fishery, operating gillnets in small boats for feeding and reproduction. Longtail (fiberglass 6–8 m), or large dhows (less tuna (T. tonggol) is an epipelagic than 30 m wooden or fiberglass) and species inhabiting in tropical to few industrial purse-seiners. However, temperate regions of the Indo-Pacific, this species is considered as one of the found almost exclusively in the neritic most important economic resources in waters close to the shore, avoiding Indian Ocean, very little information is estuaries, turbid wasters and open ocean known about the dynamic population of (Froese and Pauly, 2015). It is one of T. tonggol from this area (IOTC, 2015). the smallest species of the genus Some results of studies on Thunnus, but relatively large compared population dynamics of longtail tuna with other neritic species with a in the Indian and Pacific Oceans maximum length of 145 cm (Pierre et reviewed by Kaymaram et al. (2013), al., 2014). Estimated global catches of Abdussamad et al. (2012), Griffiths et longtail tuna increased gradually from al. (2010), Froese and Pauly (2007), the mid 1950’s to the year 2000 when Itoh et al. (1999), James et al. (1993), over 90,000 t were landed. Catches then Yesaki (1989) and Prabhakar and declined until 2005 (67,600 t). Since Dudley (1989). 2005, catch has increased continually Iranian Journal of Fisheries Sciences 17(4) 2018 778
The purpose of this study is to find used to compare the parameters some important biological aspects of T. obtained from general coefficient. tonggol such as growth, age, mortality Growth parameters including L∞ and and yield per recruit based on biological K were estimated by model progression reference points in traditional fisheries analysis using the program ELEFAN1 to provide information on population (Pauly and Morgan, 1987) within the dynamic that needed for fishery FiSAT II program (Gayanilo and Pauly, managers in the Persian Gulf and Oman 1997). Growth equation in length as a Sea. function of age (Von Bertalanffy) was: Lt=L∞ [(1-exp (-K (t-t0))] Materials and methods Where: L∞=asymptotic fork length Monthly length frequency distributions (extreme length), K= growth rate and and weight were constructed to obtain t0= theoretical age of fish at zero length. growth curves and length-weight Extreme length was estimated by relationship. Samples were collected maximum length estimation in FiSAT from five commercial landings along II software with 95% confidence. With the Hormozgan Province coastal this L∞ value, Shepherd´s method was includes 1)Jask 2)Sirik 3)Bandar abbas used t0 estimate the K value (Shepherd, 4)Kong 5)Parsian from April 2015 to 1987). The theoretical age at which the
March 2016 (Fig.1). The specimens fish has mean length zero (t0) was were caught with traditional vessels estimated by Pauly’s (1979) formula:
(boat and dhow) and for each sampling, Log (-t0) = -0.392 – 0.275Log (L∞)- a random sample was taken before the 1.038 Log (K) catch was landed. The index of growth performance The captured exemplars were (Pauly and Munro, 1984) was biometrical and gravimetrical calculated using the equation: φ= measured. Fork length (FL) was Ln(K)+2Ln(L∞) measured to the nearest 1 cm and Where L∞ and K are the growth pooled into 3 cm length classes and parameters of the Von Bertalanffy total weight (TW) to the nearest 0.01 equation. The index was compared with kg. The length frequency data smoothed estimates obtained by other authors to in order to decrease sampling error. The facilitate the intra- and interspecific length-weight relationship was comparison of the growth performance calculated by applying a power (Pauly and Munro, 1984). regression as: TW=aFLb. In this Total mortality rate (Z) was equation length is independent variable. estimated by the linearized length- -1 The parameter "a" is called the converted catch curve: Ln(Ni dti ) = a condition factor, and "b" usually + Zti designated the allometry coefficient, Where: Ni is the number of fish in assumes values around 3 for isometric length class i; dti is the time needed for growth pattern. Student’s t-tests were the fish to grow through length class i; t is the relative age where midlength is 779 Darvishi et al., Population assessment and yield per recruit of longtail tuna (Thunnus tonggol) in… reached in class i (Gayanilo and Pauly, Lc U 1- 1997). L -1 The natural mortality was estimated (U=1- LC L∞ the fraction of growth to using the Pauly’s (1980) empiric be completed after entry into the formula (as T. tonggol are school exploited phase) and Lr=38.6 cm migratory species, M multiplied by 0.8 The resource status was evaluated (Pauly, 1980)): using estimates of fishing mortality rate
Loge (M) = −0.0152 −0.279 Loge (L∞) associated with a maximum sustainable
+ 0.6543 Loge (K) + 0.463 Loge (T) yield (Fmax) and by comparing estimates Where: T is the annual mean water of the current fishing mortality rate temperature value (the mean surface (Fcurr). A number of biological temperature of the Persian Gulf and reference points estimated: 1)Fmax Oman Sea was 27°C during the defined as the fishing mortality that sampling). The current instantaneous produces maximum yield-per-recruit; fishing mortality rate (Fcurr) was 2)Fopt=M/2; and 3)Flimit=2M/3 estimated from the difference between (Patterson, 1992). the total mortality and the natural mortality: Fcurr=Z-M, and the exploitation rate (E) was assumed to be E = F/Z (Sparre., 1998). In order to determine the mean size at first capture (LC=L50%), the probability of capture estimated by backwards extrapolation of the descending limb of the catch curve to include younger age classes that were likely to be underrepresented in the catch, within the FiSAT II program (Gayanilo and Pauly, 1997). The Beverton-Holt model used to calculate yield per recruit curves (Y/R) Figure 1: Map of the sampling area and sampling sites for longtail tuna in and biomass per recruit (B/R) following Northern of the Persian Gulf and the formulas (Beverton and Holt, 1959) Oman Sea (2015-2016). using the Knife-edge selection: Results F 1 3U 3U2 U3 Y / R A W Among the 4383 specimens of T. K Z Z 1 Z 2 Z 3 tonggol collected during the sampling, B/R=(Y/R)×(1/F) dominant was from 25 to 124 cm FL Where: with mean 71 cm (Fig. 2).The weight M K L - Lc and length pairs data of 331 longtail A L - Lr tuna were obtained and length-weight relationship was: Iranian Journal of Fisheries Sciences 17(4) 2018 780
TW=0.00002 FL 2.87(R2=0.97) (Fig. 3). and 1.09, respectively and exploitation The computed growth coefficient rate was 0.69. The probability of (b=2.87) was not statistically different capture curve (Fig. 7) showed that the from 3(t-test, p>0.05). The Von fork length of T. tonggol to be attained Bertalanffy growth parameters obtained in 60.2 cm where the probability was for this species were L∞=129.6 cm, 50%. -1 -1 K=0.39 year and t0= −0.28 (Fig. 4), The yield per recruit (Y R ) and which showed this species length biomass per recruit (B R-1) analysis attained at the end of 1, 2, 3, 4 and 5th were computed using the knife-edge year are found to be 50.9, 76.4, 93.6 procedure and maximum of fishing
105.2 and 113.1 cm, respectively (Fig. mortality rate (Fmax) was 0.85 (Fig. 8). 5). The growth performance index (φ) In fact, Y R-1 increases steadily till was 8.7. the fishing mortality rate reached to 0.85 year-1 and then decline with increasing fishing mortality. The biomass per recruit was 22.3% of unexploited biomass (virgin biomass) at
Fmax point and decreased to 17.2% in current fishing mortality rate. The biological reference points were estimated and are shown in Table 1.
Figure 2: Length frequency distribution of longtail tuna in Northern of the Persian Gulf and Oman Sea (2015-2016).
The length-converted catch curve is shown in Fig. 6. The estimated instantaneous rate of mortality (Z) for T. tonggol was 1.58 year-1 (with 95% Figure 3: Relationship between total weight (TW) and fork length (FL) of longtail tuna in confidence interval of slope -1.707 - - Northern of the Persian Gulf and Oman Sea 1.454). Natural mortality and fishing (2015-2016). mortality were estimated 0.49 year-1 781 Darvishi et al., Population assessment and yield per recruit of longtail tuna (Thunnus tonggol) in…
Figure 4. Monthly length frequency distribution output from FiSAT II with superimposed growth curve for T. tonggol from Northern of the Persian Gulf and Oman Sea (2015-2016).
Figure 5: Length at age of Thunnus tonggol Figure 7: Probability of capture curve for based on Von Bertalanffy growth parameter longtail tuna in Northern of the Persian Gulf from Northern of the Persian Gulf and and Oman Sea (2015-2016) (L = 60.2 cm Oman Sea (2015-2016). 50% fork length).
Figure 6: Length-converted catch curve for Figure 8: Yield per recruit and biomass per Thunnus tonggol in Northern of the Persian recruit curves for longtail tuna in Northern Gulf and Oman Sea (2015-2016). Black dots of the Persian Gulf and Oman Sea (2015 - are those used in calculating the parameters 2016) using the selection give option. of the straight line, the slope of which is an estimate of Z. Yellow dots represent fish not fully selected by the gear used in the fishery and/or not used in mortality estimation. Iranian Journal of Fisheries Sciences 17(4) 2018 782
Table 1: Biological reference points for The length-weight relationship of T. longtail tuna in Northern of the Persian Gulf tonggol revealed an isometric growth and Oman Sea (2015-2016) (Lc=60.2 cm, -1 for this species in our study (a=0.00002, M=0.49 year ) 2 Reference b= 2.87, R =0.97). Fish growth is F F F F point 0.1 max opt limit generally isometric, and longtail tuna Value 0.47 0.85 0.25 0.33 showed this growth pattern. High values of the allometry coefficient Discussion imply that the species gains weight fast Fish stock assessment should be carried growing in length. The value of the out for each stock separately, since an coefficient estimated for a species can essential characteristic of a stock is that vary between stocks and even between its population parameters remain areas. In general, the coefficient b from constant throughout its area of length–weight relationship takes over distribution (Kamukuru et al., 2005), the values in range 2-4 (Weatherley, therefore in this study we assumed that 1972). James et al. (1993) estimated the T. tonggol belongs to unit stock. values of a and b as 0.000083 and 2.71 The size range of the individuals was respectively for longtail tuna in Indian between 25-124 cm for fork length. coastal waters. In Australia the length- Size frequency distribution can provide weight relationship of T. tonggol was information on population dynamics in W=0.00005L2.82 (Griffith et al., 2010). processes such as growth, mortality and Differences in a and b values may be recruitment, and population migration due to the changes in environmental (Azpeitia et al., 2013). The size of parameters, physiology of the fish, sex, longtail tuna caught by the Indian development of gonads and conditions Ocean fisheries typically ranges in respect to nutrition, as well as between 15–120 cm depending on the sampling date, region and methods type of gear used, season and location. (Pitcher, 2002). The fisheries operating in the Andaman Several methods are used to indicate Sea (coastal purse seines and troll lines) growth estimates: analysis of tag and tend to catch longtail tuna of small size recapture data, analysis of the hard (20–45cm) while the drifting gillnet parts of the fish (otoliths, vertebrae, fisheries operating in the Arabian Sea etc.), and analysis of cohort catch larger specimens (50–100 cm) progressions in length-frequency (IOTC, 2015). Although the type of distribution (modal progression) sampling gear may introduce a bias in (Gaertner et al., 2004). the size structure of the fish, in the In tropical areas, the hard parts current study the use of different gill changes are less pronounced, therefore nets allows for representation of all it is difficult to use a seasonal ring for exiting sizes of the longtail tuna. age determination (Sparre, 1998). So, Estimates of the condition factor and the analysis of length frequency data allometry coefficient can be related to has been used for growth of fish by ecological processes and life history. 783 Darvishi et al., Population assessment and yield per recruit of longtail tuna (Thunnus tonggol) in… indicating cohorts or age groups 1980). T. tonggol grows rapidly early in (Bhattacharya, 1967). life, reaching a length of at least 50 cm The growth parameters (K, L∞) of T. after 1 year (Griffiths et al., 2010) and tonggol in this study were (0.39 year-1, the present study showed that longtail 129.6 cm) from the Persian Gulf and tuna grew very fast in the first 2 years. Oman Sea. Previous studies have The age at zero length in our study reported their estimation on growth was -0.28. King (2013) suggested parameters of longtail tuna based on negative t0 indicates that juveniles grow otoliths and length frequency data more quickly than the predicted growth (Table 2). curve for adults. In present study, growth parameters Errors in the estimative of the growth differed from the estimates that fish parameters can be evaluated using reported by other authors. The growing the growth performance index (φ) constant which indicates a fish (Pauly and Munro, 1984) and species approaches fast to the asymptotic length within the same family are expected to (maximum theoretical) and it has been have similar φ values (Moreau, 1987). also demonstrated that it is bound to the The growth performance index ranges fish longevity (Beverton and Holt, between 8.3-8.9 (Table 2) and φ value 1959). Therefore, the bigger the value in the present study was similar to the of this constant is, the smaller the earlier reported values, which maybe longevity is. The differences in Von suggests a similar growth pattern Berthalanffy growth parameters may be across different stocks. due to the various estimation models, differences in the maximum size of fish in different areas, differences in genetic structure and/or density of food (Pauly,
Table 2: Estimates of growth parameters for Thunnus tonggol in the Indian and Pacific Oceans by various analysis methods. -1 Area L∞(cm) K(yr ) t0(yr) φ Method Reference Length- India 93 0.49 -0.24 8.3 Silas et al., 1986 frequency Japan 55 1.7 -0.089 8.5 Otoliths Itoh et al., 1999 Length- Thailand 108 0.55 - 8.7 Yesaki, 1989 frequency Length- Iran 133.8 0.35 - 8.7 Kaymaram et al., 2013 frequency Length- Prabhakar and Dudley, Oman 133.6 0.228 - 8.3 frequency 1989 Australia 135.4 0.233 -0.02 8.3 Otoliths Griffiths et al., 2011 Papua New Length- 122.9 0.41 -0.032 8.7 Wilson, 1981a Guinea frequency Papua New 131.8 0.395 -0.035 8.8 Otoliths Wilson, 1981b Guinea Length- Australia 110 0.32 -0.36 8.3 Fishbase frequency Length- Supongpan and Thailand 58.2 1.44 -0.027 8.5 frequency Saikliang, 1987 Iranian Journal of Fisheries Sciences 17(4) 2018 784
Table 2 continued: Length- Abdussamad et al., India 123.5 0.51 -0.032 8.9 frequency 2012 Length- Khorshidian & Carrara, Iran 149.5 0.3 0.06 8.8 frequency 1993 Length- India 99 0.48 - 8.4 James et al., 1993 frequency Length- India 145 0.324 - 8.8 Froese and Pauly , 2007 frequency Length- Iran 140 0.27 - 8.5 Darvishi et al., 2003 frequency Iran Length- 129.6 0.39 -0.28 8.7 Present study (Hormozgan) frequency The natural mortality in this study was The mortality rates are important to 0.49 year-1. Prabhakar and Dudley calculating the optimal fishing effort in (1989) and Kaymaram et al. (2013) development fisheries. Total mortality estimated natural mortality of 0.429 and in our study was 1.58 year-1. This 0.44 year -1 for T. tonggol in Omani and mortality rate of T. tonggol is smaller Iranian coastal waters, respectively. than the total mortality of this species Natural mortality is dependent on mean reported by Abdussamad et al. (2012) water temperature during the sampling (Z=3.72 year-1) in West Indian coastal date, disease and present of predators in waters and greater than the estimate area. The fishing mortality and given by James et al. (1993) (Z=1.22 exploitation rate were 1.09 year-1 and year-1) in the Indian coastal waters. The 0.69, respectively. Gulland (1970) variations in these values might have reported that in optimally exploited been caused by size specific selectivity stock F(fishing mortality) should be by different fishery gears of longtail equal M(natural mortality)and it is in tuna or seasonal migrations. However, case E=0.5, but Patterson (1992) even small fluctuation of growth observed that optimal E=0.5 tended to parameters may influence on calculated reduce pelagic fish stock abundance mortality rates. (i.e. T. tonggol) and suggested that E The perfect measurements of the should be equal 0.4 for optimal natural mortality of the fishes are exploitation. Since our estimate of impossible and reliable estimate of M exploitation rate was greater than 0.4 can only be obtained for an unexploited and 0.5, it can be concluded that stock (Al-Hosni and Siddeek, 1999). longtail tuna stock is under overfishing Separating M and F from Z in a heavily in coastal of Northern of the Persian exploited stock was a difficult task Gulf and Oman Sea. (Shojaei et al., 2007) and to date the One major reason for why the existing methods are based on empirical fisheries scientists study fish growth, equations that have been tested for and describe it by means of the von some groups of organisms, mainly fish Bertalanffy growth function (VBGF), is (Pauly, 1980). to perform stock assessments using the yield per recruit (Y R-1) model of Beverton and Holt (1959), or one of its 785 Darvishi et al., Population assessment and yield per recruit of longtail tuna (Thunnus tonggol) in… variants (Pauly and Soriano, 1986). In against our results in this study. fisheries management when little data Unfortunately there are limited reports on catch and fishing effort are on population assessment of longtail available, yield per recruit models tuna based on yield per recruit models might be very profitable tools for in global distribution. Using relative assessment of fish population (Gabriel yield per recruit models, Abdussamad and Mace, 1999). et al. (2012) indicated that longtail tuna The yield per recruit curve showed are currently being fished at that the maximum fishing mortality rate biologically sustainable levels, with (Fmax=0.85 year-1), which gives considerable scope for increasing their maximum yield per recruit, differs from yield in west coastal water of India. the current fishing mortality rate (1.09 In Australian coastal waters under year-1) which is estimated in this study. all MLL (Minimum Legal Lengths) Theoretically, increasing length at first scenarios, the current fishing mortality capture (Lc) motivate increase in yield. rate did not exceed biological reference This will occur when the mesh size of points, however, there is potential for designed gillnet allows immature fish to recruitment overfishing if the true age- escape and provide an opportunity for at-maturity is higher than the estimate them to spawn at least once. of 2 years (Griffiths, 2011). For other Additionally, biomass per recruit Scombrids species in the same region, showed decrease in current biomass to Taghavi Motlagh et al. (2010) showed 17.2% of unexploited biomass at Fcurr. that the biomass per recruit at the The critical range of spawning stock estimated fishing mortality rate was biomass is between 20-50% of unfished particularly lower than 15% of the biomass (King, 2013), therefore T. unexploited level and recruitment tonggol have recruitment overfishing overfishing for Euthynnus affinis . pattern in Northern of the Persian Gulf In conclusion, present study was the and Oman Sea coastal waters. first population assessment using the Biological reference points can yield-per-recruit model for longtail tuna provide guidance principles to fishery in the Persian Gulf and Oman Sea and researchers to manage the commercial all results of investigation demonstrated stocks. The current fishing mortality that this species was not at biologically rate of 1.09 year-1 was considerably sustainable. The appropriate greater than ideal fishing mortality management of T. tonggol resource in -1 (Fopt=0.25 year ) and limit fishing this area needs to control fishing effort -1 mortality (Flimit=0.33 year ) biological activities and gillnets mesh size. In the reference points and indicating that last decade (2006-2015) total catch of population of T. tonggol is heavily T. tonggol in Hormozgan Province overexploited in the Persian Gulf and (data from sampling region) increased
Oman Sea. The F0.1 calculated as 0.47 from 12,465 to 32,648 t (Iranian year -1. In optimal yield, current fishing Fisheries Statistical Yearbook, 2006- mortality does not exceed F0.1, that is 2015) and this fishing pattern should be Iranian Journal of Fisheries Sciences 17(4) 2018 786 revised and it requires the participation Valdivia, E., 2013. Growth and of all fishermen and fishery managers. mortality rates of Pseudupeneus Like other Scombridae species, longtail grandisquamis and Urobatis halleri tuna stock are transboundaries and its bycatch species in the shrimp fishery management would be fishery. Hidrobiológica , 23(3), 386- conducted in collaboration countries 393. bordering the Persian Gulf, Oman Sea Beverton, R.J.H. and Holt, S.J., 1959. and Indian Ocean. The long term A review of the lifespans and monitoring programs are required by mortality rates of fish in nature, and Indian Ocean Tuna Commission their relation to growth and other (IOTC). physiological characteristics. In Ciba Foundation Symposium-The Acknowledgements Lifespan of Animals (Colloquia on The authors are grateful of the experts Ageing). Vol. 5. John Wiley & Sons, in the Department of Biology and Stock Ltd. pp. 142-180. Assessment, The Persian Gulf and Bhattacharya, C.G., 1967. A simple Oman Sea Ecological Research Institute method of resolution of a (PGOSERI, Hormozgan Province, distribution into Gaussian Iran). components. Biometrics, pp.115- 135. References Darvishi, M., Kaymaram, F., Abdussamad, E.M., Koya, K.P., Talebzadeh, S.A. and Behzadi, S., Ghosh, S., Rohit, P., Joshi, K.K., 2003. Population dynamics of five Manojkumar, B., Prakasan, D., Scombrid fish in Hormozgan Kemparaju, S., Elayathu, M.N.K., Province (Iran). The Persian Gulf Dhokia, H.K. and Sebastine, M., and Oman Sea Ecological Research 2012. Fishery, biology and Institute (In Persian).183 P. population characteristics of longtail Fisheries Statistical Yearbook, tuna, Thunnus tonggol (Bleeker, Iranian Waters., 2006-2015. 1851) caught along the Indian coast. Fisheries administration council of Indian Journal of Fisheries, 59(2), agriculture, executive. Tehran.125 P. 7-16. Froese, R., and Pauly, D., Editors. Al‐Hosni, A.H.S. and Siddeek, S.M., 2007. FishBase Accessed March 1999. Growth and mortality of the 2008. Available at: narrowbarred Spanish mackerel, http://www.fishbase.org Scomberomorus commerson Froese, R. and Pauly, D., 2015. Fish (Lacepede), in Omani waters. Base. , version 04/2015, FishBase Fisheries Management and Ecology, Consortium,
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