Volume 1 - SUPPLEMENT of ABSTRACTS
Population Structure of the Areolate Grouper Epinephelus areolatus Stock in the Gulf of Suez
- Azza El-Ganainy
Fisheries Division, National Institute of Oceanography and Fisheries. Egypt.
azzaelgan@yahoo.com
- Alaa Osman
Zoology Department, Faculty of Science, Al-Azhar University, Assiut, Egypt
- Ezzat Abd-Allah
Zoology Department, Faculty of Science, Al-Azhar University, Assiut, Egypt
Keywords: Mortalities* Exploitation rate* yield per recruit* Epinephelus areolatus* Gulf of Suez.
Abstract
Groupers are widespread in the Red Sea; they are among the most commercially important
fishes in the region. The demographic structure and fishery status of the areolate
grouper Epinephelus areolatus in the northern Red Sea, Gulf of Suez, were studied using a
combination of length frequency and size at age data to derive information required for its
management. 597 fishes with total lengths ranged from 11.2 to 50.5 cm were analyzed. The
growth curve was derived from previous length at age data. The age composition results
showed that the fishery depends on young individuals < 24 cm 2 years old. Parameters of the
von Bertalanfy growth function were L∞ = 66.5 cm, K = 0.2 and to = -0.91 years. The mean
size at first capture (20.2 cm LT) was considerably smaller than both the mean size at sexual
maturity for females (25.5 cm LT) and the size at which yield per recruit would be maximized
(28.5 cm LT). The fishing mortality rate (F = 0.68 year−1
) was by far in excess of the
precautionary target (Fopt = 0.19 year−1) and limit (Flimit = 0.25+ year−1
) biological reference
points. In addition to growth overfishing, the stock was considered to be recruitment
overfished as the biomass per recruit was less than 10% of that at the theoretical unexploited
level. The results suggest that a substantial reduction in fishing effort will be required for the
resource conservation and stock rebuilding of E. areolatus in the Gulf of Suez.