Analyses of the non-target catch from the Egyptian Mediterranean trawlers, off Port Said

摘要

The present study aimed to analyze the non-target catch in the Egyptian Mediterranean waters, off Port Said, during the period from spring 2017 to winter 2018. The analysis revealed that from 75 non-target species, fish constituted about 69.4% of the total catch weight, whereas invertebrates reached about 30.6%. For non-target fish, 51 fishes were identified (50 bony fishes and one elasmobranch), of which 17 lessepsian species were found. The high percentage of fish (82.67%) was with an average length between 4.0 and?<9.0?cm. The highly represented fish species by numbers were:Engraulis encrasicolus(25.608%),Herklotsichthys punctatus(23.711%),Terapon puta(9.572%),Equulites klunzingeri(9.342%),Gobius niger(7.177%),Argyrosomus regius(6.280%),Alepes djedaba(4.155%),Gobius paganellus(3.397%),Sardinella aurita(2.525%),Ariosoma balearicum(1.093%) andDiplodus annularis(0.803%). Total analysis, seasonal analysis and an index of diversity (H′) for the non-target catch species were provided. On the other hand, length-weight relationship, condition factor and age composition were described for the most dominant species. For non-target invertebrates, 24 species were identified among which 13 lessepsian species were found. Shrimps and mantis shrimpErugosquilla massavensiswere the main constituents during the period of study. The authors propose to change the cod end mesh size from 2.5?cm to 4.0?cm to minimize the high percentage of non-target catch and preserve recruits of valuable species from over fishing along the Egyptian coast of the Mediterranean Sea while doing experiments to ensure the best results. Further, continuous monitoring and managements of trawlers must be put into consideration.