Infestation status of gnathiid isopod juveniles parasitic on Dusky grouper (Epinephelus marginatus) from the northeast Mediterranean Sea.

This is the first detailed documented record of Gnathiid isopod praniza larvae infestating dusky grouper, (Epinephelus marginatus Lowe 1834) in the northeast Mediterranean Sea (36 degrees 36'N-36 degrees 07'E, 35 degrees 52'N-36 degrees 25'E). Fish were sampled monthly from Iskenderun Bay during a 3-year period from 2000 to 2003 [N = 468, W+/-SD (range) = 503.69+/-342.35 g (177-2,832 g), TL+/-SD (range) = 32.39+/-9.22 cm (16.1-67.0 cm), W (total) = 0.213L (total) (2.19), r (total) (2) = 0.85]. Juveniles of the Gnathia sp. were only extracted from the epithelium of the buccal cavity. The monthly and seasonal patterns in infestation rates (mean prevalence, P = 27.35% and mean intensity, MI+/-SD = 21.35+/-16.19), and the relationship between length-weight and infested/non-infested fish were calculated. This study suggests that gnathiid parasite has no effect on the growth and general health condition of infested fish, although high intensities were observed in fish.