Age and growth, mortality and exploitation ratio of Epinephelus summana (Forsskål, 1775) and Cephalopholis argus (Schneider, 1801) from the Egyptian Red Sea coast, Hurghada fishing area

Abstract

The age and growth of two grouper fish species, Epinephelus summana (Forsskål, 1775) and Cephalopholis argus (Schneider, 1801) from 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.

Population Parameters and Exploitation Ratio of Blue Swimming Crab, Portunus pelagicus (Linnaeus, 1758) from the Bawasalo Waters Pangkep Regency, South Sulawesi

“…The total mortality, natural mortality and capture mortality rates of P. pelagicus found in Egypt's Red Sea waters were 2,929/ year, 1,285/ year and 1,644/ year, respectively (El-Kasheif, 2021). Fish species are more susceptible to activities of fishing The ratio of exploitation is very important to estimate the state of the stock is optimal, under exploitation or over exploitation (Mehanna et al, 2019). The ratio of exploitation of P. pelagicus found in this study in Bawasalo waters, Pangkep Regency, is 0.55, indicating that exploitation ratio exceeds the optimal limit (MSY).…”

Age and Growth of Japanese Anchovy (Engraulis japonicus, Temminck & Schlegel, 1846) in Coastal Waters around Shandong Peninsula, China

“…The LWR analysis reveals that anchovies in the Shandong Peninsula display a positive allometric growth pattern (Figure 7a-d), indicating that the anchovy experiences a proportionally more significant increase in weight compared to length, reflecting favorable prey and growth conditions [70]. Positive allometric growth (b > 3 in LWR) has also been observed in anchovy populations across various sea areas [26,27,39,71,72]. The mean relative condition factor (K n ) is a factor that can assess the overall health and physiological state of fish populations [73,74].…”

An evaluation for the exploitation level of Egyptian Marine Fisheries

“…The overfishing situation was observed (Table 4) and agreed with all previous studies dealing with tstock assessment of Red Sea fisheries (eg. Mehanna and El-Gammal, 2007;Mehanna, 2005Mehanna, to 2020Tesfamichael and Mehanna, 2012;Osman, 2015;Mohamed, 2016;El-Mahdy, 2017;Mehanna et al, 2016Mehanna et al, , 2017Mehanna et al, , 2018Mehanna et al, , 2019Mohamed et al, 2020). In spite of the large area of marine fisheries in Egypt, these fisheries are not exploited rationally due to the decrease of relative abundance of its fish stocks as a result of different reasons such as pollution (domestic and industrial sewages), over fishing and illegal fishing, habitat degradation, human activities on coastal areas, in addition to climate changes.…”