RECRUITMENT OF JUVENILE GOLDEN GREY MULLET, Liza aurata (Risso, 1810) AND FLATHEAD GREY MULLET, Mugil cephalus Linnaeus, 1758 IN THE NERETVA RIVER ESTUARY

Research of recruitment, growth and diet of golden grey mullet (Liza aurata) and flathead grey mullet (Mugil cephalus) was carried out on the sampling sites in estuary of Neretva; Mala Neretva, Kanal and port of Ploče. On sandy–muddy beaches, samples were collected using seine net and on deeper sites with rocky bottoms, samples were collected by using small »dip net«. Total length of body and total weight were measured. Stomach contents were analysed using inverted microscope. Prey frequency (%F), abundance (%N) and coefficient of empty stomach (%V) were determined. Also possible food competition between different species of mullet juveniles was studied, based on space and time overlap of their recruitment. Recruitment of golden grey mullet (length category of 15–20 mm in samples) lasted from October to January. Analysis of lenght–weight relationship in the area of estuary of Mala Neretva showed that population has a negative alometric growth. In analyzed stomach contents from October to February, dominant were harpacticoid copepods. There was a substantial increase in the percentage of insects in March, and gammarids in December. Juveniles of flathead grey mullet were found in samples from September to November, with small length categories of 10–15 mm in September and October. Analysis of length–weight relationship established that samples on all three sites had a negative alometric growth. Fast growth was recorded during all three months because the sea temperature was above 20 °C. In the stomachs of flathead grey mullet juveniles the dominant prey group was also harpacticoids on all three sites. Statistically significant level of competition (SI= 0.747) was determined between L. aurata and M. cephalus in the estuary of Mala Neretva, mainly because of high percentage of harpacticoids in prey content of both species