Download or read book The Experimental Trawl Catch Analysis in the Upper Gulf of Thailand and the Rational Management with Mesh Size of Trawl Net written by Masatosi Sinoda and published by . This book was released on 1987 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Experimental Trawl Catch in the Upper Gulf of Thailand and the Rational Management with Mesh Size of Trawl Net written by Masatosi Sinoda and published by . This book was released on 1987 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Analysis of Demersal Catches Taken from the Experimental Trawling Operations in the Gulf of Thailand written by Sanan Raumragsa and published by . This book was released on 1965 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contribution Marine Fisheries Laboratory written by Marine Fisheries Laboratory (Thailand). and published by . This book was released on 1971 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Trawl Fishing in the Gulf of Thailand written by Klaus Tiews and published by . This book was released on 1962 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Trawl Fisheries in the Gulf of Thailand written by Matana Boonyubol and published by . This book was released on 1984-01-01 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Trawl Fishing in the Gulf of Thailand written by Klaus Tiews and published by . This book was released on 1962 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of demersal fish catches taken from the otterboard trawling survey in the Gulf of Thailand 1966 written by Samrān Ritraksā and published by . This book was released on 1968 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of demersal fish catches taken from the otterboard trawling survey in the Gulf of Thailand 1968 written by Samrān Ritraksā and published by . This book was released on 1970 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of demersal fish catches taken from the otterboard trawling survey in the Gulf of Thailand 1967 written by Samrān Ritraksā and published by . This book was released on 1969 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ver ffentlichung der Bundesforschungsanstalt f r Fischerei written by Bundesforschungsanstalt für Fischerei and published by . This book was released on 1962 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mortality of Fish Escaping Trawl Gears written by Petri Suuronen and published by Food & Agriculture Org.. This book was released on 2005 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress has been made in reducing bycatch and discards through improving the selectivity of fishing gear. This publication examines the key factors affecting the stress, injury and mortality of fish arising from fishing processes, particularly when fish escape from trawl equipment. It seeks to identify improved methodological approaches and practices, and to consider the design of fishing gears and operations that reduce or eliminate such deaths, and to assess the problems associated with estimating the impact of unaccounted fish mortality.
Download or read book Design and Testing of Trawls written by Aleksandr Lʹvovich Fridman and published by . This book was released on 1979 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Improving the Size Selectivity of Trawl Codends for Northern Shrimp Pandalus Borealis and Redfish Sebastes Spp Fisheries in the North Atlantic written by Zhaohai Cheng and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A bottom trawl is a towed fishing gear that is designed to catch commercially important species that live in close proximity to the seafloor. In the Northwest Atlantic, bottom trawls are widely used to harvest shrimp, redfish, and various groundfish species. Coastal fishing fleets in both Canada and Iceland have been using bottom trawls to harvest northern shrimp (Pandalus borealis) and redfish (Sebastes spp.) for several decades. The codend of these fishing gears plays an important role in reducing unintended bycatch of non-targeted species and sizes of animals. Careful design and engineering of these codends is a necessary step in the fishing gear development cycle. In this thesis, I conducted different experiments, including laboratory and field work, to improve the size selectivity of codends for northern shrimp and redfish in the North Atlantic. In my first experiment, I compared the performance of different codends on the size selectivity of shrimp in the coastal fishery of Iceland. I compared codends of same nominal mesh size (42 mm) constructed using netting in the traditional orientation (T0, two-panel) against experimental codends constructed using netting rotated 45O (T45, two-panel) and 90O (T90, four-panel). My results revealed that the T90 codend retained significantly less shrimp between 9 and 19 mm carapace length than the T0 codend, and between 15 and 19 mm than the T45 codend. Since discarding of undersized shrimp is prohibited in Iceland, using the T90 codend would enable fishers to use their quotas more efficiently. In my second experiment, I compared the performance of two different codends on the size selectivity of redfish in a commercial fishery off the south coast of Iceland. The codends varied in their design, mesh size (inside-knots measurement), and construction (i.e., knotted vs. knotless). My results showed that there was no significant difference in size selectivity between the codends at lengths greater than 29 cm for S. norvegicus and 19 cm for S. viviparous. At smaller lengths, size selectivity was undetermined due to small catches at those sizes. In my third experiment, I compared the performance of four different codends on the size selectivity of redfish in eastern Canada (Unit 1, Gulf of St. Lawrence). I evaluated a traditional diamond mesh codend with a nominal mesh size of 90 mm and three experimental T90 codends of different nominal mesh sizes (90, 100, 110 mm). My results demonstrated that the traditional codend was not size selective, catching greater than 97% of redfish over all of the length classes observed. Overall, my results reveal that T90 codends improve size selectivity in which large proportions of undersized fish are successfully released. In my final experiment, I examined the hydrodynamic performance of full-scale T0 and T90 codends with and without a cover net using the flume tank located at the Fisheries and Marine Institute. I measured flow velocity, mesh shape, mesh opening, and drag at various towing velocities. The results showed that the flow velocity inside each codend was lower than the towing velocity. T90 codends had higher flow velocity and better mesh opening than the T0 near the terminal end of the codend. The total drag of each T90 codend was significantly higher than the T0. With the cover net, the flow velocity in the area between codend and the cover did not change significantly for the T0 codend, but was significantly different for the T90 (90 mm) codend. In summary, the findings from this thesis confirm the importance of codend design on the size selectivity of bottom trawls. Changes in mesh size and mesh orientation in particular, were shown to significantly affect the size selectivity of northern shrimp (Iceland) and redfish (Iceland and Canada). These results could prove helpful in the pursuit of sustainable fisheries, whereby smaller undesirable or non-targeted animals can be released from codends during towing operations, preventing their unnecessary capture and mortality.
Download or read book Ver ffentlichungen des Instituts f r K sten und Binnenfischerei Hamburg written by Institut für Küsten- und Binnenfischerei and published by . This book was released on 1962 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fish Behavior and Its Application in Species Selective Trawl Nets in the Southern New England Large Mesh Groundfish Fishery written by Natalie Frances Jones and published by . This book was released on 2015 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trawl nets have been a fixture in commercial fishing since the late 1800s. With the improvement of technologies at sea, fishing has become so advanced that many fisheries worldwide are facing diminished stock statuses. Incorporating selective designs to trawl nets separate species by mechanical or behavioral mechanisms to reduce bycatch and discards at sea. By exploiting behavioral differences between round fish and flatfish, species can be selected to be retained and caught or given escape opportunities. Modifications to a trawl net to increase species selectivity at the groundgear can allow fish to escape at depth, therefore decreasing the rate of mortality associated with the catch process and contact with the gear itself. The knowledge of how flatfish and roundfish behave around a trawl net led to the creation of an experimental groundgear. The gear was a modified rubber Riser Sweep that incorporated escape windows below the fishing line on the groundgear. The experimental net was tested against a common commercially fished net in southern New England in a comparative pairwise fashion. Two riggings of the experimental groundgear were tested in 2013 and 2014. Catch results indicate that the gear was successful in reducing winter flounder (Pseudopleuronectes americanus) bycatch while targeting Atlantic cod (Gadus morhua). Other bycatch species such as yellow tail (Limanda ferruginea) and windowpane flounder (Scopthalmus aquosus), winter (Leucoraja ocellata) and little skate (Leucoraja erinacea), longhorn sculpin (Myoxocephalus octodecemspinosus), and sea raven (Hemitripterus americanus) were also dramatically reduced in the experimental net. Though the reduction in bycatch species was accomplished as a primary goal, Atlantic cod catches decreased in the experimental net in 49 out of 66 pairs over both years of sea trials. While the experimental gear showed promise in reducing bycatch, further modifications are needed to reduce loss of target species.
Download or read book Observing Fish Behavior and Evaluating Gear Design to Reduce Bycatch of Small Mesh Trawl Fisheries in New England written by Shannon Michael Bayse and published by . This book was released on 2015 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bycatch reduction devices (BRDs) are employed in trawls to reduce the capture of unwanted species. Evaluation of these devices is critical to determine how well bycatch is reduced, and to assure that target species catch is retained at a commercial level. This dissertation evaluated new BRD design for the silver hake (Merluccius bilinearis) and longfin inshore squid (Doryteuthis pealeii) fisheries. Due to the small size of the target species, both of these fisheries require small mesh condends, 76 mm or less. Bycatch concerns are inherently greater for small mesh fisheries due to the potential of retaining most fish that enter the trawl. Evaluation of BRDs was conducted by both video analysis and catch comparison techniques to determine the effectiveness of the new trawl design. At the time of this work, BRDs mandated in the Maine silver hake fishery had proved ineffective, warranting a new BRD design. An experimental trawl with a large mesh belly window and Nordmøre-style grid caught a commercial quantity of silver hake and reduced the catch of regulated groundfish species (p
