Otolith morphology analysis is one of the main tools used for fish or fish stock identification. Moreover, otolith shape can also be used in animal dietary studies (stomach content) for the identification of prey fishes and their size according to the relationship between fish and otolith sizes. In the present study, the relationship between fish length and otolith morphological dimensions was investigated for the sabre squirrelfish, Sargocentron spiniferum (Forsskål, 1775) (family: Holocentridae). Samples of 185 fish were collected from the coast of the Red Sea, Egypt. To analyze the relationship between fish and otolith, otolith morphometric measurements (length, width, area, perimeter, weight, sulcus, and ostium) and shape factors (aspect ratio, compactness, form factor, rectangularity, roundness, ellipticity, squareness) describing the outline shape were extracted using image analysis. Generalized linear models were applied for the relationship between body length and each otolith morphology feature. From the relationships between the total length of fish and fourteen morphology features, only otolith length, caudal length, and squareness were significantly correlated with fish size. Our results provide more information for the relationship between fish length and otolith morphometric features.

The age and growth of two grouper fish species, Epinephelus summana (Forsskål, 1775) and Cephalopholis argus (Schneider, 1801) from the Egyptian Red Sea off Hurghada, were studied based on the otolith readings. The maximum longevity of the two species was 10 and 6 years for E. summana and C. argus respectively. The age group II was the most dominant age group in the catch forming 46.09 % for E. summana and 22.33% for C. argus from the total collected samples. The asymptotic standard length (L∞) and the growth coefficient (K) were estimated as 63.39 cm and 0.13 year-1 for E. summana and 44.22 cm; and 0.26 year-1 and C. argus, respectively. The total mortality was computed as 0.82 and 1.31 year-1 for E. summana and C. argus, respectively. The mean values of natural mortality were 0.33 and 0.56 year-1 for E. summana and C. argus, respectively. Accordingly, the fishing mortality rates were estimated as 0.49 and 0.75 year-1 for E. summana and C. argus, respectively. The exploitation rates of E. summana (0.6) and C. argus (0.57) along with the fishing mortality rates reflect the overexploitation situation of the two serranid species in the Egyptian Red Sea.

Rabbitfishes, family Siganidae, are one of the most abundant fishes inhabiting the Red Sea and now widely distributed in the Mediterranean. Age and growth of Siganus rivulatus, the most common species, were studied from samples collected randomly between October 2017 and October 2018 from Shalatein landing site. Otoliths of 2000 specimens were used for age determination and the maximum attained age for this species was four years. The von Bertalanffy growth parameters L∞, K and to and the instantaneous annual rates of total, natural and fishing mortality were estimated and consequently the exploitation rate was determined. It is found that the current exploitation level is higher than the optimum one reflecting the intensive exploitation of S. rivulatus in the Southern Red Sea, Egypt. Yield per recruit analysis revealed that fishing effort should be decreased. This can be adopted through closed seasons/areas, increase of mesh size, increase of minimum landing size and setting of a total allowable catch (TAC).

Otolith Mass Asymmetry in Two Parrotfish Species, Chlorurus sordidus (Forsskål, 1775) and Hipposcarus harid (Forsskål, 1775) from Hurghada, Red Sea Coast of Egypt