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Showing 6 results for Gillnet
M.s. Tamasoki, S. Gorgin, R. Ghorbani, A.a. Gharehaghaji, S.m. Aghilnejad,
Volume 25, Issue 4 (1-2017)
Abstract
Every year, after fishing period, the sturgeon gillnets are assessed base on physical characters by the management of sturgeon fishes in Golestan Province. Net are put aside and replaced by new one if they qualification are not net. In spite of importance of strength ropes, unfortunately, there is a little research in this regards. In addition, previous research are not applied storage conditions and physical damages. Therefore, researcher are determined to do a research in this regards. For this reason some materials from new net, storage net, damaged net, put aside net, etc. collected and tested by an Instron. Then data analyzed by factorial test in complete randomized and variance and average compared in 5% significant level by SPSS version 17. The results shows that there is not significant difference between new net (blank) and new net kept in storage for two years in strength point (p>0.05). However, there is significant difference in breaking point, damaged nets (p<0.05). Regarding the effect of reducing, the net strength during the storage, lack of significant difference between new storage net, represents a quality loss in making of new nets.
N. Haghighatjou, S. Gorgin, A. Hosseini, M. Babanejad,
Volume 27, Issue 1 (5-2018)
Abstract
Crimson snapper (Lutjanus johni Bloch, 1792) is the most important commercial species in the Persian Gulf and the Oman Sea. This species is caught by gillnets in the coastal waters of Bandar Abbas. In the present study, the gillnet with 17 cm stretched mesh size (knot to knot) is used for investigating the selectivity of gillnet used for catching the crimson snapper by length-girth relationships in the coastal waters of Bandar Abbas. Sampling was performed in May and July 2017. The total numbers of 1107 specimens were caught after 210 times of gillnetting. The weight, total standard length and girth of 4 points of body (locations of eyes, operculum, beginning of the dorsal fin and maximum girth) were measured for all specimens. Regression of length-girth, length-weight and selectivity curve were drawn based the data. Results showed that the total length was increased by increasing the body girth and weight of fish. Based on the body girth of two points including branch girth and maximum body girth, the selectivity of gillnet ranged from 62 to 76 cm in which the optimum length was 69 cm that is higher than Lm50. Therefore, it can be concluded that gillnet with 17 cm mesh size is suitable for catching crimson snapper.
S.a. Hosseini, Sh. Enayati,
Volume 27, Issue 3 (8-2018)
Abstract
Efficiency of various meshes of gillnet and trolling gear was investigated for catching kingfish (Scomberomorus commerson) in coastal waters of Sistan and Baluchestan province in 2007. In gillnets with mesh sizes between 57 to 110 mm and netting of monofilamnet and multifilament, the size distribution of kingfish ranged between 40 to 78 cm of fork length, which all specimen caught were immature. In mesh size of 146 mm and 171 mm, the length range of the species was larger, in which the frequency of immature fish for the respective mesh sizes was 19 and 11. In general, most fish was captured by wedging in the all mesh sizes. The size range of kingfish captured by the trolling was between 52 and 147 cm, of which more than 50 percent of caught fish were immature. The proportion of kingfish catches in the gillnets of 57-110 mm mesh sizes is about 13% of the total catch composition, for which the mesh sizes are considered as the dominant gillnets for capturing the species in this area. The conribution of kingfish catches in 133, 146, and 171 mm mesh sizes was 1.1, 52.3 and 18.9% respectively, with a 146-mm mesh size is considered as a dominant gillnet for this species. The implementation of the ban on the use of 57 to 110 mm mesh sizes for exploitation of kingfish is mandatory, which the mesh size of 146 mm and above seems to be appropriate for responsible fishery of the species. However, recommendation of standard mesh size needs to be re-examined in field trials.
Seyed Hesam Kazemi, Seyed Yusef Paighambari, Parviz Zare, Saeid Gorgin,
Volume 29, Issue 4 (10-2020)
Abstract
Yellowfin Tuna (Thunnus albacares) is one of the most important commercial and neritic fish species which has known because of ecological importance and wide distribution around the world. The aim of this study was to determine relative index of abundance for Yellowfin Tuna from 2007 to 2016, also we evaluated effect of some explanatory variables (year, month, vessel tonnage and net height) of catch per unit effort data in traditional gillnet fishery standardized by general linear model (GLM) in the Oman Sea. Standardized catch per unit effort is an important entrance in stock assessment as an annual abundance index. The results of this study have shown that all explanatory variables influence CPUE significantly in GLM model with lognormal error distribution; CPUE of Yellowfin Tuna increased 0.007 and0.0016 by raising one ton of vessel' tonnage and one meter of net height, respectively. Relative index of abundance of Yellowfin Tuna has the lowest quantity in 2011, remain stable till 2013 then increase to highest level in 2016, which is shown the catch rate can increase by raising catch effort. There is a seasonal trend in standard CPUE of Yellowfin Tuna with the highest catch rate in cold season. Monthly relative index of abundance has shown highest catch rate occurred in February and March.
Mohammad Saberi, Yousef Paighambari, Parviz Zare, Saeid Gorgin, Manoochehr Babanezhad,
Volume 29, Issue 6 (2-2021)
Abstract
One of the methods of standardization of gill nets is to determine the appropriate mesh size for each species. The purpose of this study was to determine. This study was aimed to determine the suitable mesh size of drift gillnets for catching skipjack (Katsuwonus pelamis).The sampling operation was carried out by the lange boat in the spring of 1397. The fishing tool consisted of drift gillnet for Skipjack tuna with a stretched mesh size of 160 mm. Fork length and body length were measured in two areas of skipjack tuna body. The total numbers of 394 specimens were measured, the fork length range was 38 to 77 cm with mean and standard deviation of 55.02 55 ± 5.90 cm. The highest frequency of Skipjack was in the range of 48-58 cm with 77%. The equations of linear relations between fork length and gill circumference: Gop = 0.577 FL + 1.866 with coefficient of determination 0.926 and linear relation for fork length and body circumference Gmax = 0.922 FL – 9.750 with a Coefficient of Determination 0.963 were gained. The elongation rate was 17% for gill circumference and 21% for the body circumference. In general, based on the present study, a drift gillnet with a mesh size of 136 mm can be used to capture Skipjack, which is slightly smaller than the minimum mesh size used by fishermen.
Shahram Ghasempour, Saeid Gorgin, Rasoul Ghorbani,
Volume 31, Issue 1 (4-2022)
Abstract
Gillnets are sometimes abandoned or lost at sea due to sea storms, tearing by a hard object, or the failure of fishermen to find the fishing area. In this study, the data related to the frequency of illegal abandoned fishing nets in Golestan province were collected through field patrols and questionnaire information from spring to winter 2016. 88,465 abandoned fishing nets were collected in the coastal waters of Golestan Province. The results showed that 78.2% of the discovered nets belonged to Caspian kutum, carp, and common roach, 10.4% of them belonged to sturgeon nets, and 11.4% belonged to beach seines and other fishing nets. Among the interviewed fishermen, 49.2% believed that 10-20% of the nets were lost at the sea, and about 6% believed that more than 40% of the nets were lost. In investigating the causes of losing fishing nets in seawater, 52% of the people believed that the nets were stolen. In other words, human factors are one of the main reasons for the loss of the nets. 25.2% of the people consider strong waves and 15.3% of the fishermen, tearing by boat fins, 6.3% of not being able to find the location of the net, and 1.2% of other factors such as rot of nets are considered to be the cause of the gill nets loss.
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