Floating cages are isolated, with a circumferential walkway for operation purposes, or grouped, with a walkway that forms a raft. Cage farms are anchored with cables to anchorage facilities on the sea or lake floor. Off-shore cages are submerged when there is a risk of damage by high waves in stormy seas, and refloated when the storm passes.
Production management in cages and pens is based on removal of waste matter from the culture unit by the water flow. Although this maintains high water quality in the cages, it generates an ecological nuisance. In many places in Israel and other countries, nature and ecological protection associations are attempting to eliminate this production method and replace it with production in inland ponds, where water purification regulations can be enforced. Production is usually very dense, similar to the density in intensive production ponds. Fish are routinely treated and harvested from the walkway or raft around the cages, and boats are used for transportation of feed and for harvest. Fish farming in cages in landlocked water sources is common in Indonesia and the Philippines. In Israel, there are a number of marine cage farms in the Gulf of Eilat and in the Ashdod port on the Mediterranean coast. Cage farming in the Gulf of Eilat is gradually phasing out, due to a governmental decision. Recently, an off-shore cage farm facility has been established. There is no commercial production in floating cages in deep reservoirs.
NCM is part of Israel's Oceanographic and Limnological Research (IOLR), a non-profit organization under the Ministry of Infrastructure. The research and development program began with the domestication process of the gilthead seabream, Sparus aurata. Issues like reproduction control, larval rearing, live food-chain, nutrition, diseases, grow-out technologies and genetics were addressed, applying the highest scientific standards. In the middle 1980’s, the framework of the technology was ready to be implemented in floating cages out in the Gulf of Aqaba/Eilat. The commercial realization of this technology started in the early 1990’s by ARDAG, a company belonging to five Kibbutzim situated in the Southern Arava Valley. In the mid 1990’s, another company built an additional farm close by. At present both companies produce between 2200-2500 tons per year, a value of US $ 12.5 million.
Most of the fingerlings are produced by 3 hatcheries in Israel; one belongs to and is operated by ARDAG, Eilat, and two are located on the shore plains south of the City of Haifa (Israel Salt Co., Atlit, and MADAM, kibbutz Maagan Michael). Some of the production of fingerlings is aimed at inland fish farming, such as the hybrid stripe bass, barramundi (Lates calcifer). The hatchery in Atlit is also experimenting in production of a few marine ornamental fish. Another producer is located in the Port of Ashdod (on the Mediterranean Sea), with a production of 500 tons annually. Besides these producers there are a few others, who produce smaller quantities of fish per year.
All together the annual production of marine fish in Israel is over 3,000 tons. Most of this production consists of the seabream (over 85%). Other species are the European seabass Dicentrarchus labrax, the American red drum Scienops ocellatus and some other miscellaneous species.
Efforts were made in the past and at present as well to develop technologies for farming fish (like seabream) in floating cages out in the offshore Mediterranean Sea. However, winter weather conditions as well as a very moderate slopping bottom make this a demanding challenge. The entrepreneurs have come to the conclusion that the only way to achieve the goal of culturing fish en-mass in the open sea is to develop a cage (or an assemblage of cages) that would avoid the storms’ energies by sinking to deep enough waters where the waves are hardly felt. Once the storm is passed, the system would be brought up to the surface. Trials were conducted in the 1990’s and activities were resumed in 2005 with very encouraging results.
Another culture system is being developed in Israel, which is titled Land-Based Mariculture. This is a Re-circulating Aquaculture System (RAS) in which the water is continuously treated by an array of biofilters. A pilot plant using this technology, which is driven entirely by airlifts, is being built at present (summer 2005) and should be operational in the following autumn. Before returning to sea the water can be used to raise a series of organisms such as macro-algae, bivalves, sea urchins etc. This technology, once proven economically viable, may replace the fish cage production system in the Gulf of Aqaba/Eilat, which lately the government has decided to remove from the water, due to pressure from environmentalists and controversy regarding the influence of added nutrients to the environment.
If successful, the plans are to increase production to 3,000 tons annually by 2010 and to 10,000 tons by 2020.
An additional aquaculture technology, titled Integrated Mariculture System (IMS), developed at the National Center of Mariculture is the basis for one fish farm in Israel. The main organism grown on this farm (SeaOr Marine) is an abalone, which is fed on macro-algae growing on the effluent of fish ponds at the same farm. The effluent quality is high and the clean water is returned to the sea. The national goal is to utilize the heated seawater from power stations along the coast for growing fish. One of the technologies considered for this purpose is the Mega-Flow RAS system. Warm waters will allow the fish to grow throughout the winter. A small pilot has been running using the warm effluent for a few years with very encouraging results.
At NCM, R&D is being conducted on a few other fish species such as the white grouper Epinephalus eanus, the gray mullet Mugil cephalus, sea urchin, and macro-algae. Technology wise, wet-land is being experimented with growing halophytes as the organisms which take up nutrients from the effluent of the fish ponds.
Mariculture in Israel employs some 300 workers, and the total income was estimated at around US$ 20 million in 2004.