Aquaculture Africa 2021

March 25 - 28, 2022

Alexandria, Egypt

PRODUCTION OF MULLET IN CAGES: EGYPTIAN CASE

 Sherif Sadek ,  Aquaculture  Consultant Office, Cairo, Egypt

aco_egypt@yahoo.com

 



 Mullets are important species in Egypt, representing 14 % of the total  fisheries and aquaculture production  and landing 2.1 million tons in 2019 . Tot  al  mullet production  in 2019 was 285,000 tons, of which 235,000 tons was produced by aquaculture.  More than 26,000 ca ges  are  found  near the  Nile estuary  of Roseta, with a  total  cage  water volume of 15.7 million m3 , resulting in  an average production of 13 kg/m3 ,  and  total production volume of  201,000 tons . The species produced in these 26,000 cages include  Nile and blue tilapia (59%), mullet (27%), silver carp (13%) and European seabass  (1%)  (GAFRD, 2021).  The  major advantages  for cage culture of mullet in the Nile River over other methods of fish culture include: the anticipated high profitability levels; the use of existing water bodies, thus reducing the pressure on land; the requirements of relatively low capital outlay; the ease of movement and relocation; the flexibility of management ( for example, broodstock management of grey mullet, Mugil cephalus).  The production of mullet (mainly Lisa ramada ) in  Nile  cage aquaculture began  in 2006 with annual production 19,200 tons , and increasing to 35,400 tons in 2012  and 54,300 tons in 2019 (GAFRD, 2021).  This presentation will describe traditional mullet cages  (10 x10 x 4 m net depth and 10 x 15 x 5  m net depth)  culture  management with 1.5  to < 3.0  tons of mullet/cage/18 months with an average weight of 3–5 fish per kg) . For the first 15 months,  Nile  river  cage  farmers feed mullets  a diet of  wheat bran, stale bread inconsumable and raw dried pasta and during the last three months, these cage farmers feed a compressed sinking/ floating pellets (25% CP). The feed conversion ratio (FCR) during the 1.5 year is estimated for 1:3.5. Producers usually stock 20,000 to 50,000 mullet fry (0.1 g) in the nursery cages (5 x 5 m and net depth 3 m) for the first year and in the second year, the fish are moved into larger cages (10 x 10 m x net depth 5 m) with a  fingerling  stocking density of 20-30 gm/m3 .   Several researcher s  have complete d experimental trials for the mullet cage culture.  Over a 10-month period, Essa et al. (2012) studied t he effect of  three different stocking density (9, 12 and 14 kg/m3) on growth performance, feed utilization, production and economic feasibility in an experimental trial where thinlip grey mullet (L . ramada) fingerlings (>80 g) were reared in floating net cages (700 m3 )  located in the brackish waters of the Rosetta branch of the Nile river. Fish were fed a commercial diet with 23% crude protein, at a rate of 2% of total biomass. The highest growth was observed at a density of 12 fish/m3, with  individual total weight gain of 243 g and average daily gain of 0.83 g fish/day. Azazi et al. (2012) e stimated c osts and r eturns for grey mullet (M. cephalus) c ommercial c age p roduction (300 and 600 m3 )  in Manzala lake northern Nile delta. Results indicated that cage volume had positive effects on the economic performance of mullet cage culture, with a production  1.5  and 4. 9 kg/m3 in small and large cages, respectively.  This investigation concluded that mullet cage culture wa s successful in brackish water environment and growth is directly related to stocking density and feeding regime. Results demonstrated  that under optimum conditions in this experimental trial, mullet production was economically feasib le, when compared to  traditional  fish farm  cage production .  Thus , it is  recommended that the approach  described in Azazi et al. (2012)  will promote greater and more effective  development of  fish cage culture in the Nile river, especially th e  culture of mullet species .  In  conclusion, the mullet used for cage farming need to be propagated in hatcheries ,  mullet feed costs  need to be reduced  by improving  the economics of feed formulation, and  that continued improvements in minimizing the environment impacts and increasing sustainability of mullet cage farming will advance commercial cage production of mullets.