Ecology of the Mottled grouper (Mycteroperca rubra) in the
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
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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