الفهرس 
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Abstract
Family Carangidae represents one of the important families in the Egyptian sector of the Red Sea. Carangid or Jack fishes are abundant, valuable and economical fish food. The present work has been suggested due to the rarity of biological, population dynamics, stock assessment and fisheries studies with respect to two Carangid species Carangoides bajad and Caranx melampygus from the southern Red Sea, at Elba National Park (Shalateen fishing port), 520 Km southern of Hurghada, Egypt during the period from November 2013 to October 2014.
The present study is a part of a project executed in Assiut University to study the biology and fisheries of the Red Sea fishes, so more advanced techniques and statistical methods were considered.
The results of the present work can be summarized in the following points:
Part I: Identification of fish stock
Identification of the stocks of Carangoides bajad and Caranx melampygus by: a- Morphometrics and meristics, b- Scale characteristics.
1. Morphometrics and meristics.
Morphometrics, meristics and the type of allometry (i.e isometry, negative allometry and positive allometry) were estimated for the two Carangid species studied.
Discrimination between sexes in each of Carangoides bajad and Caranx melampygus was possible by using certain morphometric indices. The type of allometry in each of males and females of the two aforementioned species was estimated according to the bivariate concept. No sexual dimorphism was observed in the meristics of each of Carangoides bajad and Caranx melampygus under investigation.
2. Scale characteristics
The scale characteristics of the two Carangid species considered were studied in the terms of morphometry and Scanning electron Microscopic techniques.
The valid useful scale characteristics for systematic purposes were determined in the term of morphometry and scanning electron microscopic techniques. A wide spectrum of size-free intraspecific variations between different body regions was recorded in each species in terms of scale morphometric indices. The scale characters included the overall form of the scales and their morphometrics, shape of the first circuli, form of circuli, the outer lateral and inner lateral circuli and granulations of caudal field. Moreover, the forms of the lateral line canal scales were valid in differentiation between species under study.
Part II: Fishery Statistics
There are main seven fishing landing sites along the proper Red Sea; they are from north to south: Ataka, Hurghada, Safaga, Qusier, Baranies, Shalateen and Abu-Ramad (Red Sea province). Baranies fishing harbor is considered the principal fishing port along the proper Red Sea where about 53.16% of the total landings comes from it, followed by Hurghada (21.60%), Qusier (9.93%), Shalateen (6.55%), Ataka (2.69), Safaga (3.40%) and then Abu-Ramad (2.56%).
The catch composition of the Shalateen fishing area during the fishing years 2010 to 2014 were Grouper, Emperors, Carangid fishes, Soldier fishes, Narrow-barred Spanish mackerel, Needie Fish, Red porgy, Snapper and others fishes which hook and line caught fishes. The most common species groups represented in the gill and trammel nets’ catch were red mullet, Rabbitfish, Wrasses, Breams and Mackerels fish.
Fluctuation in the total teleost and Carangid catches from the Southern Red Sea (Hurghada to Shalateen) was observed in the period from 2005 to 2014.
Part III: Biology and population dynamics
1. Biological Studies
- Age of the two species was determined and the maximum life span was 8 and 12 years old for Carangoides bajad and Caranx melampygus respectively.
- The time of annulus formation on the scales takes place in different months for the two species (December for Carangoides bajad and November for Caranx melampygus).
- The relationship between SL and scale radius (S) was found to be linear with high correlation (r = 0.90 for Carangoides bajad and r = 0.91 for Caranx melampygus). Such relationship was described by the following equations:
Carangoides bajad: SL = 113.43 + 59.67 S
Caranx melampygus: SL = 42.64 + 67.68 S
Accordingly, the equations used in back calculation were found to be as the following:
Carangoides bajad: SLn = 113.43 + Sn/S*(SL – 113.43)
Caranx melampygus: SLn = 42.67 + Sn/S*(SL – 42.67)
- The length–length relationships of Carangoides bajad and Caranx melampygus through the whole period of investigation were described as the following:
Carangoides bajad: TL = 1.17*SL + 17.79 R² = 0.99
TL = 1.08*FL + 12.08 R² = 0.99
FL = 1.08*SL + 5.45 R² = 0.99
Caranx melampygus: TL = 1.19*SL + 17.80 R² = 0.99
TL = 1.10*FL + 10.90 R² = 0.99
FL = 1.08*SL + 6.54 R² = 0.99
- The fishes attained most of this length in the first year of life then Sharpe decrease in the rate of growth in length with increase of age occurred. Carangoides bajad attainted its highest growth rate in length (41.5%) in age group I while that of Caranx melampygus was (35.7%) in age group I.
- The growth in weight of the two Carangid species was isometric and the obtained length-weight equations (W in g and SL in mm) were found to be:
Carangoides bajad: W = 0.00005*SL2.8827 R² = 0.98
Caranx melampygus: W = 0.00004*SL2.9333 R² = 0.99
- The highest value of the condition factor Kn was recorded in May for Carangoides bajad and in September for Caranx melampygus; while the lowest value was recorded in November for Carangoides bajad and in July for Caranx melampygus.
- The growth rate in weight exhibited its higher values in age group IV for Carangoides bajad and in age group VII for Caranx melampygus.
- The most dominant age groups in the catch were age group I (23.78%) and age group II (45.36%) for Carangoides bajad, while for Caranx melampygus, age group 0 and age group II were the most dominant ones contributing 21.61% and 18%, respectively of the total collected samples.
2. Population parameters
- As regards Von Bertalanffy growth model, the curvature parameter K indicates that Carangoides bajad (K = 0.24) approached its asymptotic length (L) faster than Caranx melampygus (K = 0.17).
- The parameters of the Von Bertalanffy growth model were estimated as:
Species L∞ K W∞ to
Carangoides bajad 576.88 0.24 4553.56 -0.86
Caranx melampygus 701.08 0.17 8903.28 -1.013
Part IV: Management
The yield per recruit of Carangoides bajad and Caranx melampygus was estimated by means of Gulland equation (1969). The results show that in Carangoides bajad, the present level of fishing mortality (F = 1.52), age at first capture (Tc = 1.34) and natural mortality (M = 0.34), the yield per-recruit (Y/R)’ was obtained at Emax = 0.61. In Caranx melampygus, the present level of fishing mortality (F = 1.75), age at first capture (Tc = 3.57) and natural mortality (M = 0.25), the yield per-recruit (Y/R)’ was obtained at Emax = 0.86.
Conclusion
The present results revealed that the stock of Carangid species in the Egyptian Red Sea appears to be overexploited since the current fishing mortality is higher than F0.1 and Fmax. Thus a fishing mortality reduction is necessary in order to avoid future loss in stock productivity and landings.