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Abstract Lutjanidae fishes are considered with high food value as well as their economic value. This study aims to gain field, scientific and practical experience and to study some aspects of biological and marine fisheries through studying the biological characteristics of two species of Lutjanid fishes, including age estimation, growth rates in length and weight as well as total length relationship with weight, in addition to the breeding and estimation of fish stocks, as well as the analysis of the statistical results of this type in the fisheries, this study could be summarized as follows: I: Knowledge of the common species of the Lutjanidae family • The common species of Lutjanidae family were found in Hurghada, Red Sea, Egypt, and eight species were recorded as following: Lutjanus ehrenbergii, L. quinquelineatus, L. bohar, L. argentimaculatus, L. gibbus, L. fulviamma, L. Lutjanus, and L. monostigmus. Identification of Fish Stocks Fish stocks of Lutjanidae fishes were identified by morphometric, numerical and protein content. Morphometric and Meristic characteristics The morphometric characteristics of two species of Lutjanidae fishes, as well as the alumetric (isometric, negative alomoteric, and positive alometric) parameters were studied. The distinction between qualitative Lutjanus quinquelineus and Lutjanus ehrenbergii was made using some morphometric parameters of 18 morphometric measurements. In addition, the study included some numerical characteristics and their relationship to growth, and it was Summary 111 proved from the study that the number of rays in the dorsal fin, Pectoral and anal fin is fixed in both types subject to study. • SDS-Polyacrylamide Gel Electrophoresis In the present study, muscle proteins were measured in the types of Lutjanus quinquelineus and Lutjanus ehernbergii using the electrophysiological system, which showed the same number of protein tapes (20 protein tapes). Also, the muscle proteins of the same types were classified into several tapes. These tapes showed a difference in quantitative parameters, where Lutjanus quinquelineus have unique bands of molecular weights as following (266.43, 215, 119.82, 30.51, and 27.18), while the Lutjanus ehernbergii type has the following molecular weight proteins (75.97, 50.81, 30.86, 30.07, 27.18 and 16.6). The present study is the first attempt to study the genetic relationships of two species using general muscle proteins. Based on the protein band pattern shows that the species analyzed are more or less closely related to each other. Future studies using biochemical-genetic markers and DNA barcoding hopefully will establish new ventures in the field of stock management and conservation of snappers. II: Fishery Statistics Data for catch were collected from 2004 to 2015 for the purpose of assessing fish stocks and determining the status of current Red Sea fisheries with a focus on Lutjanidae fisheries. The present study showed that the catch in the fishing areas around Hurghada area during the last 10 years from 2004 to 2015 included the following types of fish: Gropper, Emperor, Jack, Soldier Fishes , Spanish Mackerel, , Needle Fish, Seabream, and Porgy in addition to snapper, all these types were caught by the strings. Other fishes are also more commonly caught by gill nets and tributaries nets such as: Goat, Rabbit, Parrot, Soldier Fish and Caranx respectively, according to the statistics of the General Authority for Fisheries in Hurghada. Also, the study showed that the total catch Summary 111 of whole bone fishes and Lutjanidae fishes in particular in the landing area of Hurghada , Red Sea, Egypt during the period from 2004 to 2015 were different. III. Biological characteristics and assessment of fish stocks A( Biological characteristics: The age of two species (L. quinquelineatus and L. ehrenbergii ) was estimated using scales. The annual rings were clearly shown. The annual rings began to appear on the scales in December for L. quinquelineatus and November for L. ehrenbergii The total length - the total weight relationship of the two species was studied by linear regression analysis using the statistical methods, which can be represented by the following equations: L.quinquelineatus W = 0.0118 L= 3.098 R 2 = 0.95 TL in cm L. ehrenbergii W = 0.0194 L= 2.911 R2=0.96 TL in cm The relation between the standard length-scale radius was first determined, this relation was found to be linear. The linear regression does not pass through the origin, the equation representing this relationship was: L.quinquelineatus TL = 0.628 + 0.4778 R2 = 0.952 L. ehrenbergii TL = 0.5626 + 1.9181 R2 = 0.929 B: Stock Assessment The fishery biology, including growth, mortality and reproduction of the Lutjanidae species were used to determine ages and estimate the backcalculated lengths-at-ages, growth rates and then the von Bertallanfy growth parameters (VBGPs; K, Land to). The maximum age was found to be 4 years for hoth sexes males and females. The von Bertallanfy equation for the mathematical description of the growth in length could be written as follows: Lutjanus quinquelineatus For growth in length Lt = 35.5 [1 - e -0.35(t + 1.3)] For growth in weight Wt = 750.62 [1 - e -0.35(t + 1.3)] 3.0986. For growth in length Lt = 32.4 [1 - e -0.32(t + 1.3)] For growth in weight Wt = 545.50 [1 - e -0.32(t + 1.3)] 3.0986 The total mortality coefficient ’Z’, natural mortality coefficient ’M’, and fishing mortality coefficient ’F’ were estimated to be 2.16 ,0.78, and 1.38 year -1 , in L. quinquelineatus, 2.45 , 097 , and 1.47 year -1 in L. ehrenbergii, respectively. The current exploitation rate ’Ecur’ was 0.8 year-1 . The spawning season was found to extend from March to July, and the maximum absolute fecundity was estimated to be 088883 eggs in L. quinquelineatus. and 083333 eggs in L. ehrenbergii. The yield and biomass per recruit were estimated using the Beverton and Holt’s yield per recruit Model (1957). Results indicated that the stock of Lutjanidae in Hurghada fisheries is currently overexploited where both Emax = 0.71 year-1 and E0.1 =0.61 year -1 are lower than Ecur = 0.8 year-1 . It is recommended that the current exploitation rate be reduced to the level of E0.1, in addition to protecting the spawning stock biomass during the spawning season and reducing the natural mortality rates. Species L∞ K To Ø’ Lutjanus quinquelineatus 35.5 0.354 -1.310 2.65 Lutjanus ehrenbergii 32.4 0.474 -1.0185 2.69 In the study of the length -age distribution of the lutajanidae fish, the maximum age of both species was 4 years. The first age group is predominant in the catch of both species of lutajanid fish in the study area. yield per recruit was calculated for lutajanidae fish using the Beverton and Holt model (1957). To obtain the highest yield per recruit, the mortality rate of the fishing process should be reduced by L. quinquelineatus 58.%. and 54 % L. ehrenbergii. Summary 111 IV: Fisheries Management In the light of the above findings and with the fact that all target species in the Egyptian Red Sea fisheries are in a situation of overexploitation, L. quinquelineatus and L. ehrenbergii, snapper fishery in Hurghada fishing area can become more profitable and can achieve more economic returns if it given more attention and care. So, a detailed knowledge on behavior, biology and population dynamics of the all fish stocks in the area is a vital step and should be done to put a full concept for how to exploit and expand this promising resource that will achieve the desired sustainable development of the Lutjanidae fishery in Hurghada. |