Age, growth, mortality rates and corresponding yield estimates of the snubnose emperor Lethrinus borbonicus from south Sinai coast, Gulf of Suez, Egypt

Abstract

Age-based demographic analysis were conducted to assess the current status of fished stock of the snubnose emperor Lethrinus borbonicus in South Sinai coast, Gulf of Suez, Red Sea. L. borbonicus is one of the most abundant emperors in the area, representing about 10% of the total artisanal fishe ry in south Sinai coast. Seasonal samples were collected from the commercial small scale fishery during the period from June 2005 until April 2007. The otoliths were used for age determination. Validation of the ageing method was carried out by analyzing the seasonal length frequency distributions. The life span was found t o be four years. The estimated von Bertalanffy growth parameters from otolith age read ing were L �= 36.76 cm, K= 0.344 year -1 and t o= -0.321. Instantaneous rates of fishing mortality (F) were beyond the limit reference point compared with estimated insta ntaneous rates of natural mortality (M), indicating that there is currently a risk to t he sustainability of that stock. Results of the exploitation rate (E=0.583) and relative yie ld per recruit showed that the snubnose resource in the Gulf of Suez is overexploi ted and that small 16 individuals are the target of the fishery referring to recruitm ent overfishing also. Some implications for the fishery management for decreas ing fishing effort are required.