Fish stocking and culture-based fisheries are valid management practices compensating the shortfalls of catch in overfished systems. Improving the survival of fish to be stocked–pre-conditioning and acclimatization to prevailing conditions in the receiving water body potentially improves their survival. Determining the appropriate size of fish for release requires knowledge of their likely impacts on native fishes and the ecosystem in general, together with a cost–benefit analysis. In the present study 16000 mullet, Mugil cephalus (11.41±0.04 cm) (10.5 ±0.8 g) tagged with the magnetic wire codes were used. Two nursing treatments were carried out to determine the influence of re-stocking nursing mullet fry on the enhancement of the stock of grey mullet in Wadi El-Rayan Lake as enclosed body. In the first treatment (T1) grey mullet was tagged with coded wire-tagging in the earthen pond and nursing for 21-days then release in the Wadi El-Rayan Lake. While, in the second treatment (T2) grey mullet was release immediately to Wadi El-Rayan Lake after the tagging with coded wire-tagging. Monthly samples were collected from the Lake periodically to follow up the growth performance over 716-days. The results showed that grey mullet survival (%) recorded 81.4% and 71.88% for T1 and T2, respectively. Mullet resulted in higher growth rate, length and weight either any fish sample date verses previous sample or between initial restocking mullet fish (Table 1).
The present findings indicated that it is important for fish to be stocked at a time when they are able to adapt to the new environment quickly and thus learn how to forage for natural foods with minimal delay. Determining the appropriate size of fish for release requires knowledge of their potential impacts on local fish and the ecosystem in general, along with a cost-benefit analysis. This work is a part of the USAED project outputs, " Stock enhancement and production of the Grey Mullet fry – a sustainable choice ", funded by a grant from the Middle East regional cooperation (MERC) program, U.S. Agency for International Development, Bureau for the Middle East. (Project Number: M33-038; Award Number: SIS70017GR33038).