نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه شیلات، دانشکده شیلات و محیط زیست، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
2 مرکز تحقیقات ذخایر آبزیان آب های داخلی ، موسسه تحقیقات علوم شیلاتی کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، گرگان، ایران
3 گروه آمار، دانشکده علوم پایه، دانشگاه گلستان، گرگان، ایران
4 پژوهشکده اکولوژی دریای خزر، موسسه تحقیقات علوم شیلاتی کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، ساری، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The diameter of the ring connected to the balustrade Conical Lift Net was initially 1.5 m. But gradually the diameter of the attached ring increased Today it is about 4 meters. The seems to increase the diameter of the ring This increased the number of non-target fish in this method. The purpose of this study was length frequency and species composition of non-target fish caught in Conical Lift NetMay 1997 in two fishing ports of Babolsar and Amirabad by four fishing vessels during 33 torrents at a depth of 40-50 m. After identifying the species caught, the total length and weight of the specimens were measured. From a the total of 193 fish caught, the highest and lowest percentage of total relative frequency fish species Alosa caspia were (37.8%)and Gasterosteus aculeatu (4.7%). Relative frequency of other species caught in Babolsar and Amirabad ports Syngnathus abaster were 38.8% and 28%, Gasterosteus aculeatu 50% and 0%, Mugilidae 11.11 and 18.2%, Alosa caspia 0% and 41.7%, respectively. Rutilus frisii kutum was 0% and 12%. The results also show that the frequency of fish caught in Amirabad fishing port is higher than Babolsar fishing port and strongly dependent on area (p < 0.01). The results indicate the high pressure resulting from the production of Bycatch fishing on non-commercial species in Amirabad fishing port. Most frequency in Babolsar and Amirabad fishery ports were respectively in the length class of 4.5-5.5 cm Gasterosteus aculeatu and length class of 15.5-5.5 cm Syngnathus abaster in fish.
کلیدواژهها [English]