Estimation of the stability of a fishing vessel during purse seining

One of the reasons for the emergency of a fishing vessel, as well as for the failure of fishing equipment, is the sudden tension of the purse rope, which occurs when the fishing equipment is pulled. As a result of the loss of stability the vessel may enter the encircled seine area and even capsize. There are a number of measures to improve stability during the operation of the vessel. However, when designing fishing equipment, it is necessary to know forces acting on the vessel from the seine side. The article presents a method for assessing the static stability of a vessel with a static application of the tension force of the purse rope. As a result of the study, an expression for determining the static heel angle using a three-dimensional representation of the vessel is given. During simulation the geometrical parameters of the purse rope in the process of purse seine were taken into account. The tension force of the purse rope is also presented as a variable.

Conditions for stability of the “vessel-purse seine” system during purse seining

In the process of tightening the rings of the lower seine line, significant forces of hydrodynamic resistance of the netting can capsize the vessel or pull it into the encircled seine area. There is a risk of damage to the propeller-rudder system of the vessel. The list and trim of a fishing vessel can occur. It affects the safety and comfort of the crew, leads to malfunctions of fishing equipment and mechanisms, and can cause accidents. During the vessel’s operation, there are a number of measures to improve stability. However, when designing fishing equipment, it is necessary to know the forces acting from the seine side on the vessel. The article discusses the relationship between the vessel and the seine during purse seining. On the basis of the developed mathematical model of the tension force of the purse rope, taking into account the geometrical parameters of the warp during purse seining, conditions for stability of the “vessel-purse seine” system were obtained.

Fishing on Porpoise

Since the late 1950s, millions of dolphins have died as bycatch in the American yellowfin tuna industry. These deaths were not caused by accidental incidents between humans and dolphins, but rather were the result of a common fishing method used to catch yellowfin tuna that fishermen called “porpoise fishing” or “fishing on porpoise.” Although fishermen had caught tuna alongside dolphins since the 1930s, mass dolphin bycatch did not begin until the late 1950s, when the fleet converted from live-bait pole-and-line fishing to purse seining. This conversion—labeled the “purse-seine revolution”—occurred in response to economic and geopolitical pressures that threatened the future of the industry and was made possible by technological advancements that made purse seining a more effective method for catching yellowfin tuna. This conversion fundamentally altered the relationship between fishermen and dolphins. This article argues that the origins of mass dolphin bycatch are rooted in the purse-seine revolution and lie in the nexus of the economic, geopolitical, and technological developments that led to this conversion.

PROSPECTS OF DEVELOPING AUTOMATED SYSTEMS OF CONTROL OVER OF PURSE SEINING AND MID-WATER TRAWLING PROCESSES

The article describes efficient operation of catching vessels, which mostly depends on their automation level. Development and improvement of technologies of mid-water trawl fishing and purse seining will be oriented to form automated systems for these very promising fishery methods. The experience of the development and operation of such systems in the fleet proves the increased productivity of the quality of work. Automated processes of mid-water trawling and purse seining will help to shorten operation costs of catching vessels due to decreasing the number of catch failures that reach 50% at present. Purse seine trawling and deep-sea trawling are characterized by a complex interaction of the crew with a technological control facility that includes a purse seine or trawl, a ship equipped with fishing gear, navigation and fish retrieval equipment. The process of purse seining and mid-water trawling consists of several stages, most of which require processing a large flow of input information, issuing commands in a short period of time, and taking into account dynamics of vessel maneuvering, as well. The resulting misalignment of these factors becomes a great number of catch failures and damages of fishing gear. Microprocessor systems with low cost and great functional flexibility can optimize the process of vessel operation control and close the gap between the amount of information and possibility to use it. The development of microprocessors has great opportunities due to creating the automated technical process management system.

Investigations on purse seine operations off central Kerala during late 1990s and recent technological changes

Purse seining is one of the important fishing methods for pelagic fishery resources. The results of investigations on mechanised purse seine operations during late 1990s off central Kerala are presented in this paper along with recent technological changes in the sector. Since its introduction in commercial fisheries, several changes and improvements have taken placein the design and operation of purse seines. The dimensions of the gear which was about 320x28 m during early 1970s, increased to 823x73 m during late 1990s and further to 1200x100 m towards 2015. Mesh sizes used in the main body of the seine which were 12-13 mm during the early days of introduction of the gear, increased to 20-46 mm in recent years. Therewas an upward shift in vessel sizes which reached up to 22 m LOA in recent years, with a significant escalation in installed engine horsepower to 285-510 hp. Mechanised purse seine vessels started using fish finding equipment, navigational and communication facilities like Echosounder, global positioning system (GPS) and very high frequency (VHF) radio, inrecent years. The role of technological skill of skipper and crew are very important in ensuring the success of purse seining operation and there is a need for technological facilitation in terms of the use of fish finding equipments like sonar, potential fishing zone (PFZ) information based on satellite based remote sensing, possible use of fish aggregating devices and adoption of gear handling equipment such as power blocks.

Purse seining in India - a review

Purse seining is one of the most efficient and advanced commercial fishing methods of recent times, used for harvesting shoaling fishes. Purse seines are surrounding nets in which the bottom of the net is closed after encircling the fish school, by a pursing line which prevents fish from escaping downwards by diving. In India, purse seining was introduced in the south-west coast in the late 1950s to harvest shoaling fishes like anchovies, sardines and mackerels. With the success of purse seining in the country, there were rapid technological changes in the purse seine fishing method and substantial increase in the number and size of both fishing craft and gear. This present review provides an insight into the developmental changes in purse seine fishing in India and highlights future strategies.

Automated hydraulic systems for transport of fish from fishing gears with vacuum fishpump

New techniques of fish tranport from fishing gears aboard is proposed for a case of mixed aggregations of chub mackerel and japanese sardine. These species resume their mass migration to the Russian waters since 2014. Submersible impeller pumps with hydraulic power drive are used usually for catch transport aboard in the world practice of purse seining of mackerel. However, this technique is unsuitable for mixed aggregations of mackerel and sardine because the impeller pump could damage the sardine. Applicability of the vacuum and waterjet pumps for this case is considered. The vacuum fish pump TransVac was designed in 1982, initially for transfer of damage-sensitive fish from fishing vessel to shore fish processing plant, and the waterjet fish pump SilkStream was designed in 1988 for transfer of alive fish and later was adapted for fish transport aboard from trawl and seine nets. Both types of fish pumps are recommended for the medium- and large-capacity fishing vessels working with the mixed aggregations of sardine and mackerel. Using of these pumps together with freezing equipment allows to avoid losses in quality of catch.

The Capture Fishery Based Small Pelagic Business Development Opportunities Analysis with Purse Seine Fishing Gear in Maluku (Case Study on Financial Aspect in West Seram Regency)

<p class="zhengwen"><span lang="EN-GB">The study aims to find out and analyze the influence of running cost, shore cost, fishing duration and seasonal climate on profitability of purse seining small pelagic fishery business group in West Seram Regency in purpose to find out capture fishery development prospect by using such equipment in West Seram Regency. The data used in this study is primary data, i.e. a data collected from respondents through interview. Respondents are selected purposively from population of purse seining capture fishery business group. Multiple linear regression analysis method is applied to estimate the influence of running cost, shore cost, fishing duration and seasonal climate on the profitability variables (ROA). The findings reveal that running cost affects positively profitability, shore cost affects negatively and significantly profitability, fishing duration affects negatively and significantly profitability. On the contrary, seasonal climate does not affect profitability of purse seining capture fishery. Further, it is said that there is still a chance to develop purse seining small pelagic fishery business group under the condition that the activity has to be accompanied with control over running cost, shore cost, and fishing duration. <s></s></span></p>

Quantification of interactions between the Portuguese sardine purse-seine fishery and cetaceans

Interactions between cetaceans and the purse-seine fishery operating along the whole Portuguese continental coast were studied based on on-board observations from 2010 to 2011. Cetacean presence and mortality were estimated and characteristics under which interactions were most likely to occur were identified. Observations were made on 163 fishing trips (0.7% of the average annual number of fishing trips) and 302 fishing operations/hauls. Cetaceans were present during 16.9% of fishing events; common dolphins (Delphinus delphis) accounted for 96% of occurrences, mostly overnight in summer and early autumn. Regression models showed that cetacean presence during a fishing set was significantly (p &lt; 0.05) associated with sardine catches, effort, and latitude/longitude. Encirclement and mortality occurred in 2.3 and 1.0% of fishing events, respectively. Encircled species were the common dolphin, bottlenose dolphin (Tursiops truncatus), and harbour porpoise (Phocoena phocoena), but only common dolphin showed mortality (three individuals); raised to fleet level, estimated total mortality rates of common dolphins were 69 (95% CI 37–110) in the north and 91 (95% CI 55–165) in the south for 2010 and 78 (95% CI 47–140) in the south only for 2011. The estimated annual mortality rate due to purse seining is 113 (95% CI 3–264) common dolphins, which is ∼0.63% of the current most optimistic estimate of population size for the Portuguese fishing area (SCANS II). The wide confidence limits, as well as variation between years, reflect low observer coverage, emphasizing the need for increased monitoring to cover gaps in the spatial and seasonal distribution of observer effort and provide reliable estimates of bycatch.