Ecology of the Mottled grouper (Mycteroperca rubra) in the eastern Mediterranean


Andrey Aronov and Menachem Goren


Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel



Abstract: The mottled grouper, Mycteroperca rubra, is the most abundant grouper in the shallow rocky habitats <40m depth along the eastern Mediterranean. A study carried out from May 1999 to July 2002 revealed that the fish reaches a length of over 83.5 cm (total length), which is the longest reported for M. rubra. The growth equation was found to be total length(cm) = 15.192*Ln(age(years))+31.108. The size and growth rate of this fish found along the Israeli coast contradict the "Levantine nanism theory".

M. rubra is a protogenic hermaphrodite. Females become sexually mature at the age of 2+ years and the youngest male found was 3+years. The oldest female and male examined during the research were 13+ and 19+ years respectively.

The breeding season along the Israeli coast is from February-March to the end of May.  During this period monthly aggregations of up to 500 fish were observed at traditional sites. Estimated female fecundity was found to be ca. 570,000 oocytes X weight (kg).

Fish comprised 98% of the stomach content of the mottled groupers. A single prey, Siganus spp., made up ca. 68% of the food biomass. We suggest that the success of the mottled grouper in establishing a large population in the eastern Mediterranean has been mainly due to the opening of the Suez Canal that enabled the invasion of Indo Pacific Siganus spp., which is its main food source.


Key words: Mycteroperca rubra, eastern Mediterranean, fish reproduction, sex reversal, diet.



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