University of Guilan Caspian Journal of Environmental Sciences 1735-3033 1 1 2003 01 01 The qualitative index assessment of selective sturgeon gillnet fishing for sustainable exploration of the Caspian Searesources 67 71 3840 10.22124/cjes.2003.3840 EN Ali Asghar Khanipour Mirza Koochak Khan Higher Vocational & Technical Fisheries Training Center, Rasht, Guilan Province, Iran Babak Aminian Mirza Koochak Khan Higher Vocational & Technical Fisheries Training Center, Rast, Guilan Province, Iran Journal Article 2020 01 12   In order to study the quality of the gillnets used for sturgeon fisheries in the estuaries leading to Caspian Sea, the fisheries cc of Iran (SHILAT) launched a sampling program on the types of nets currently utilized by fisherman in Anzali, Babolsar andTurkman ports, in Guilan, Mazandran andGoIestan provices respectively.Three types of nets were investigated as the following: 210 Dl18l100Imm (used to catch sevruga fish) 210 DI24l150z'mm catch Sturgeons) (used to  210 Di'60I25D!mm (used to catch Beluga) Three types of nets were used to catch sevruga sevrga, Acetra and Beluga respectively. There has been a noticeable decline in the quality of the nets, which was proportionate tothe duration of their use in actual fishing operation. The nets were classified in terms of quality decline of new nets as (100%), nets used in one fishing season as (75%), nets used in two fishing seasons as (50%) and nets used for three fishing seasons as (25%).  After having 1. Cut mashes of transverse, normal and 1DT x 10N, attempts were made to experiment the samples using dynamometer and twistmeter. The experiment entailed qualitative indexes such as the breaking power of iines, elacitlcity, Z score of twist, S twist. primary mesh bar and secondary mesh bar.  The results obtained, indicated that the average length of primary mesh bar for sevruga shows a meaningful difference at  95% of probability rate while the average '  secondary mash bar for huso huso indicates difference at 99% of probability on the normal probability curve.  Key words:  Net, Gillnet, polyamide, Net quality, Caspian Sea.   <strong>References</strong>  Sarfaraz. Ali Akbar and Bozorgnia. Aboulghassem 1991 “Agricultural test design and Analysis“ .Jehad  -e-  Daneshgahi Ferdowsi university — Mashhad Samad, Aohreh & Esfandiary. Mahtash 1990,‘ “Statistical principles in experiment designs".University of Tehran publication centre.  Howell David C, (I989). Fundamental Statistics for the Behavioral Science, PVS. KENT Publishing Company. Alekssev AP. (1971) Fish behaviour and Fishing techniques. Baranov, F.l. (1994) The Capture of fish by gill nets, Matrer. Poznaniyu Russ. Ryobolo.3 (6). Ben Tuvia, A. and Dickson, W. (WD). (1997) Proceeding of FAO Conference, on fish behaviour in relation to fishing techniques and tactics, FAO FISH. Rep. Brandt. A.V. (1984) FISH Catching methods of the world, Fishing news (Books) ltd,London. Hamley. JM. (1975) Review of gill net '«_ selectivity. J.Fish. Res. Board. Melienkov. V. N. (1991) Construction of Fishing Gears & the techniques in applying them Agroprahidat p.387 Nisniresky .V. (199?) "Technological basis of Ind ustrial fishing".    https://cjes.guilan.ac.ir/article_3840_340e9ba6aee9627d3e1c36571a27e2d1.pdf