چكيده انگليسي :
The objective of the present study was classification of beach seins based on catch and value of productions during the years 1996-2012. In the present study the catch of 130 beach seins in three provinces; Guilan, Mazandaran and Golestan, for each effort and species (Rutilus frisii kutum, Liza spp., Cyprinus carpio, Rutilus rutilus, Vimba vimba, Chalcalburnus chalcoides, Shads, Aspius aspius, Barbus sp, Abramis brama, Stizostedion lucioperca, Salmo trutta caspius, Esox lucius and Silurus glani) was used as input data. According to the results, among catch of 14 species/groups, kutum represented the highest propotion of total catch at 56.78%, followed by mullet, carp and shads with 31.81, 6.54 and 3.48% of total catch. According to catch of species/groups, three main groups can be divided easily. Also, the same results achieved based on catch values of 6 species/groups as kutum, mullet, carp, roach, shads and pike-perck. The one–way ANOSIM catch similarity test indicated that coverage rates of different years were homologous and similar, but the coverage rates of different months, regions and periods were not similar. Also, there were significant differences in community composition of fishes in catch of beach seines among three times; three durations; three regions and seasons (in all cases MRPP, p<0.001). During 1996-2000 species Rutilus rutilus, Vimba vimba, Chalcalburnus chalcoides, Aspius aspius,Barbus sp, Salmo trutta caspius and Silurus glani in the years 2000-2005 species/groups shads, Abramis brama and Esox lucius and in the years 2005-2012 species Cyprinus carpio and Stizostedion lucioperca were indicator species. Also, in the west region of the Caspian Sea species/groups Vimba vimba, Chalcalburnu schalcoides, Aspius aspius, Barbus sp, Abramis brama, Stizostedion lucioperca, Esox lucius and Silurus glani; in middle Rutilus frisii kutum, shads and Salmo trutta caspius and in east species/groups mullets, Rutilus rutilus and Cyprinus carpio were identified as indicator species.
كليدواژه :
خوشهبندي , گونههاي شاخص , ماهيان استخواني , صيد , پره , درياي خزر
