1. Institute of Animal Science; Agricultural Research Organization; Bet Dagan 50250 Israel
2. Robert H. Smith Faculty of Agriculture, Food and Environment; Hebrew University of Jerusalem; Rehovot 76100 Israel
3. National Center for Mariculture; Israel Oceanographic and Limnological Research; Eilat 88112 Israel
4. The Carver Biotechnology Center; University of Illinois; Urbana IL 61801 USA
5. Faculty of Science; Institute of Evolution; University Haifa; Haifa 31905 Israel