Artificial Reefs off the Mediterranean Coast of Israel

Abstract

The south-eastern region has been shown to be the most oligotrophic part of the Mediterranean Sea (see Kimor and Wood, 1975; Lakkis and Lakkis, 1980; Kimor, 1983), which is generally considered to be the most impoverished large body of water known (Ryan, 1966). Berman et al. (1984) and Azov (1986) demonstrated the oligotrophic nature of the water, recording very low chlorophyll a concentrations (0.12–0.137 mg C m−3) in the neritic zone 2 km off the northern coast of Israel. These low levels of primary production are reflected in the higher trophic levels of the food web. The marine fishery yield from the Israeli Mediterranean continental shelf is relatively low at less than 4000 tonnes per year (Grofit, 1993). Certain fish and marine invertebrates, however, are considered to be gourmet food and obtain high market prices in Israel. Many such fish are the groupers (family Serranidae) and sea breams (family Sparidae) that are associated with rocky substrata. Thus, most of the rocky seabed along the Mediterranean coast of Israel (mainly submerged sandstone or‘kurkar’ridges) provides habitat preferred by commercially important species. Israeli fishermen locate and fish these areas intensively. These fishing grounds, however, constitute less than 10% of the Israeli continental shelf (Adler, 1985). During the last two decades, fishing pressure on these sites has grown rapidly and some may have already been over-fished (S. Pisanty, personal communication). Increased spear fishing by SCUBA and skin divers and the activities of sport fishermen have additionally reduced the macro- fauna of these limited benthic habitats.