Buoy Line Research Articles

Hauling Snow Crab Traps in Eastern Canada: A Study Documenting Tension in Ropes

Entanglement in commercial fishing gear is one of the main factors inhibiting the recovery of critically endangered North Atlantic right whales. Installing low-breaking-strength (LBS) components in the buoy lines and main lines of stationary fishing gear may be a viable solution for some fisheries. But is it an effective solution for deep-water trap fisheries? This study quantified in-line rope tensions observed during fishing operations for snow crab (Chionoecetes opilio) in Newfoundland and Labrador, Canada. We conducted a controlled fishing experiment in which we documented the loads experienced while hauling fleets of traps. The results showed that several factors contributed to the loads observed, including the components of the traps, the presence of crabs, and environmental conditions such as wind direction and wave height. According to the statistical models, the maximum tension from the estimated marginal means was 477.53 kgf in the buoy line and 987.99 kgf in the main line for the baited hauls, which exceeds the safe working load (154 kgf) of the proposed low-breaking-strength components. Our results suggest that LBS components are not a viable solution for this deep-water fishery.

Small innovation for sustainable use of fisheries resources

Influenced by Rio Declaration, Code of Conduct for Responsible Fisheries provided the principle toward sustainable fisheries in 1995. Reduction of wastages became a major issue. The author first accessed that the total amount of finfish discards in prawn trawling was similar to the coastal fisheries’ production in PNG and it was serious wastage. He also proved the over-estimation of global discards. A newly developed semi-demersal cuttlefish trammel-net successfully excluded bycatch of sub-legal individuals of flounder. He clarified that the process of declining of ghost fishing function after gear loss for cage trap and gillnet is represented with a survival function, on which the duration of ghost fishing and mortality were quantitatively estimated. He developed a technique for buoy line with an intermediate float to avoid entanglement of the line around seabed rocks. The author advocates research toward small innovation, through which many researchers can contribute to sustainable development.

Effect of length of buoy line on loss of webfoot octopus pot

Effect of length of buoy line on loss of webfoot octopus pot

Three-Dimensional Oscillation Dynamics of the In Situ Piston Rod Transmission Between Buoy Line and the Double Hinge-Connected Translator in an Offshore Linear Wave Energy Converter

Force and displacement measurements have been performed in situ on the piston rod mechanical lead-through transmission in the direct drive of the second experimental wave energy converter (WEC) 3 km offshore at the Lysekil research site (LRS) during a 130-day continuous full-scale experiment in 2009. The direct drive consists of a buoy line and a piston rod transmission with a double-hinged link (DHL) at the lower end connecting the point absorbing surface-floating buoy to the translator of an encapsulated permanent magnet linear generator on the seabed. The buoy line is guided by a funnel in the buoy line guiding system 3.2 m above the generator capsule. The 3 m long piston rod reciprocates through a mechanical lead-through in the capsule wall, sealing off seawater from entering the generator capsule. A setup of laser triangulation sensors measures the relative lateral displacement of the piston rod. This paper introduces a method and a system of equations for calculating piston rod relative tilt angle and piston rod azimuth direction of tilting from the relative lateral displacement measurements. Correlation with piston rod axial displacement and forces enables evaluation of the three-dimensional (3D) oscillation dynamics. Results are presented from 2 weeks after launch and from 3 months after launch in altogether four cases representing two different stages of wear in two different sea states. Piston rod tilting from accumulated wear in the buoy line guiding system is separated from tilting due to elastic displacement. Structural mechanical finite element method (FEM) simulations verify the magnitude of elastic displacement and indicate negligible stress and strain at the mounting point of the laser sensor setup. The proposed theory for piston rod 3D motion is validated by the experiment. As the experiment progressed, wear in the buoy line guiding system accelerated due to splitting of the buoy line jacketing compound, thereby increasing the piston rod tilt angles. Over 94 days into the experiment, 21.8 mm of accumulated wear in the buoy line guiding system had altered the characteristics of the piston rod oscillations and increased the maximum piston rod relative tilt angle by 0.39 deg in the predominant azimuth direction of wave propagation. Further accumulated wear in the buoy line guiding system led to buoy line rupture 130 days after launch. The results presented in this paper have been used in assessments for improving the mechanical subsystems in subsequent experimental WECs based on the Uppsala concept.

Jellyfish monitoring on coastlines using remote piloted aircraft

In the last 10 years the number of jellyfish shoals that reach the swimming area of the Mediterranean Sea are increasing constantly. The term "Jellyfish" refers to animals from different taxonomic groups but the Scyphomedusae are within the most significant one. Four species of Scyphomedusae are the most conspicuous ones inhabiting the studied area, the Barcelona metropolitan area. Jellyfish are usually found at the surface waters, forming big swarms. This feature makes possible to detect them remotely, using a visual camera and image processing algorithms. In this paper we present the characteristics of a remote piloted aircraft capable to perform monitoring flights during the whole summer season. The requirements of the aircraft are to be easy to operate, to be able to flight at low altitude (100 m) following the buoy line (200 m from the beach line) and to be save for other users of the seaside. The remote piloted aircraft will carry a vision system and a processing board able to obtain useful information on real-time.

Acoustic tracking of sperm whales in the Gulf of Alaska using a two-element vertical array and tags

Between 15 and 17 August 2010, a simple two-element vertical array was deployed off the continental slope of Southeast Alaska in 1200 m water depth. The array was attached to a vertical buoy line used to mark each end of a longline fishing set, at 300 m depth, close to the sound-speed minimum of the deep-water profile. The buoy line also served as a depredation decoy, attracting seven sperm whales to the area. One animal was tagged with both a LIMPET dive depth-transmitting satellite and bioacoustic "B-probe" tag. Both tag datasets were used as an independent check of various passive acoustic schemes for tracking the whale in depth and range, which exploited the elevation angles and relative arrival times of multiple ray paths recorded on the array. Analytical tracking formulas were viable up to 2 km range, but only numerical propagation models yielded accurate locations up to at least 35 km range at Beaufort sea state 3. Neither localization approach required knowledge of the local bottom bathymetry. The tracking system was successfully used to estimate the source level of an individual sperm whale's "clicks" and "creaks" and predict the maximum detection range of the signals as a function of sea state.

Analysis of hydrodynamic behavior of a submersible net cage and mooring system in waves and current

Failure of net cage and mooring system is of great concern to the marine aquaculture industry. To avoid the structure failure in storm waves and current during typhoon events, net cage can submerge below the water surface in practice. A submersible net cage and mooring system is analyzed by numerical simulation and physical model test. The numerical model is established based on the lumped mass method and principle of rigid body kinematics. A series of physical model tests are conducted to validate the numerical model of single net cage and grid mooring system in waves and current. Numerical results correspond well with data obtained from physical model test. The results indicate that when net cage is submerged below the water surface, the deformation of net cage in waves can be improved significantly, and the tension force on the anchor line, bridle line and grid line will decrease significantly. However, the tension force on the buoy line in the submergence condition is larger than that in the floating condition. Different relative submergence ratios are also considered in our numerical simulation, and a relative submergence ratio equal to 0.1 is suggested here. The tension reduction ratio (56%) for the four-cage system is larger than that for the single-cage (52%) and double-cage systems (44%).

Keeping Tabs on Quagga Mussels

This article discusses a device for early detection of quagga mussels that uses a monitoring buoy line in reservoirs. The design allows the buoy line and attached anchor to remain in the water, while only the monitoring line is pulled up to check the data. The monitoring line slides up and down the cable and allows the line to spin around the cable without becoming entangled. The design for the monitoring buoy is provided, along with construction for the buoy and monitoring lines.

DOCKING CONTROL FOR A BIOMIMETIC AUTONOMOUS UNDERWATER VEHICLE USING ACTIVE VISION

–A localization system using visual information for the guidance and navigation of a biomimetic-autonomous underwater vehicle (BAUV) is proposed. The BAUV is commanded to track a buoy line of a docking station from a distance. The purpose of the visual sensor is to assist the position estimation for the vehicle. An extended Kalman filter that combines observational information with navigational data is shown to be effective in reducing positional uncertainty of the BAUV and environmental features. Experimental results in a water tank show the validity of the proposed method.

FISHING GEAR INVOLVED IN ENTANGLEMENTS OF RIGHT AND HUMPBACK WHALES

Interactions between marine mammals and fishing gear are an issue of global concern. Entanglements in the western North Atlantic are a major source of injury and mortality for endangered large whales. In this study, entanglements of 31 right whales (Eubalaena glacialis) and 30 humpback whales (Megaptera novaeangliae) were analyzed to determine the types and parts of gear involved. When gear was identified, 89% (n= 32) of the entanglements were attributed to pot and gill net gear; however, a wide range of specific gear types were implicated. Despite gear recovery, gear type was not identified in 20% (n= 9) of the cases. Although pot gear was recovered from both species equally, gill net gear was less frequently retrieved from right whales (n= 2) than humpback whales (n= 11). When gear part was identified, 81% (n= 21) involved entanglements in buoy line and/or groundline. For right whales, the most common point of gear attachment was the mouth (77.4%); for humpback whales, the tail (53%) and the mouth (43%) were common attachment sites. Four right and three humpback whales in this sample were known to have died subsequent to entanglement. However, when identified, the gear types and parts involved in lethal cases were not substantially different from entanglements with non-lethal outcomes. Large whales can become entangled in a wide variety of fishing gear types and parts, and additional insight will depend on continued efforts to document entanglements and recover associated gear.

외줄낚시에 대한 대문어의 행동과 낚시형상 설계

The single line hook fishery for giant pacific octopus, Parotopus dofleini is one of the important in coastal Kangwon-do of Korea, where was caught an average of 4,000 ton during the period of 1996~2000. The fishing gear is consisted of a single buoy line, a buoy and a hook. In this study, the responses of giant pacific octopus to single line hook gear were examined in an experimental tank using a video camera in order to know hooking mechanism and improve hook. Giant pacific octopus tend to envelop the bait with their arms by rush or slowly swimming towards it. When they rush to the bait, they show much feeding behaviour as withdrawing after enveloping the bait using two arms. But when they approach with slowly swimming to bait, they show feeding behaviour as stopping after enveloping the bait using one arm. and then, the highly hooking rate appeared more often in the case of latter then former. The average feeding time on a sardine, giant pacific octopus and pork fat showed the range of 1 to 30 min, 10 to 50 min, and 50 min to over 1 hour, respectively. This indicates that it takes longer time for giant pacific octopus to eat the tough meat than the soft meat. The performance concerned with hooking showed that the `B` type hook with a short shank was more favorable than the `A` type hook with a long shank. However, the `A` type hook has the advantage of easy dropping out caught octopus, compared to the `B` type.

Estimación de la profundidad de trabajo de anzuelos de un palangre atunero prototipo de la flota de altura de Isla de Margarita (Venezuela)

Based on two fishing trips carried out in the Caribbean Sea in May 1997 and in June 1998, on board of deep sea tuna longline fishing boat, from Chacachacare, Margarita Island, Venezuela, the shape and tension of the longline were determined under working conditions, and the operational depth of hooks were estimated by mechanical simulation method. Lineal scale factor for simulation of a prototype section of six hooks (C L ) was 150 and force scale factor (C R ) was 370.9. Vessel speed during the operations and sections sagging rate, for trial on test panel, ranged from 4.9 knots (55.3%) to 7.1 (80.5%). The angles of incidence at the ends of the main line of prototype ranged between a mean value of 10.4o (± 0.97 SD) and 29.75o (± 1.59 SD), with a mean value of tension between 2.42 kgf (±. 0.46 SD) and 5.35 (± 1.10 SD). The hooks No1 and No6, in a range of vessel speeds, reached depths between 63.9 and 70.4 m, the No2 and No5 reached depths between 89.8 and 103.8 m, and the hooks No3 and No4 reached depths between 103.2 and 133.1 m. The estimated hook depths showed an inverse relation with the speed at which the main line is set (V L ), the sagging rate (k) and the angles of incidence at the end sections of main line (joint between the buoy line and two longline sections). The estimation of horizontal tensions shows a direct relationship with k and V L.

Free‐floating drifter for photochemical studies in the water column

A free‐floating drifter was designed to directly determine in situ photochemical production rates, photolysis rates, and light fluxes in seawater. This drifter consisted of six trays that were suspended in series from a single buoy line. The trays were constructed so that the attached quartz vessels, containing filtered seawater, were exposed to both downwelling and upwelling irradiation. The quartz vessels were sealed at both ends with ribbed TFE Teflon stoppers that permitted multiple subsampling without introduction of a headspace. The free‐floating drifter was used to study photochemical processes in antarctic waters. It performed well during 12–15‐h deployments, even in rough seas with sustained winds between 15 and 26 m s−1. Although not tested here, the drifter should perform equally well in the study of photochemical processes in freshwater environments.

Summer incidence of humpback whales on the west coast of South Africa

A total of 14 sightings of 25 humpback whales was recorded from temperate waters of the west coast of South Africa in summer (December–February). In addition, a 6,45 m individual (estimated age 6½ months) stranded at St Helena Bay in February 1982, and a 6,15 m individual (estimated age 4½ months) was found ensnared in the buoy line of a lobster trap off Saldanha Bay in December 1990. These records suggest that certain individuals, particularly juveniles, may not undertake the summer feeding migration. Although the 6,45 m individual was emaciated when stranded, the 6,15 m individual had been feeding on stomatopods, indicating that some individuals feed opportunistically during the summer off the west coast of South Africa.

Bougainvillia aberrans (Cnidaria, Hydrozoa), a new species of hydroid and medusa from the upper bathyal zone off Bermuda

Bougainvillia aberrans n.sp. is described from Bermuda in the western North Atlantic Ocean. Specimens were collected at a depth of 150 fathoms (274 m) from the polypropylene buoy line of a crab trap. The hydroid colony of B. aberrans is erect, with a polysiphonic hydrocaulus, a smooth to somewhat wrinkled perisarc, hydranths having a maximum of about 16 tentacles, and medusa buds arising only from hydranth pedicels. Medusae liberated in the laboratory from these hydroids differ from all other known species of the genus in having a long, spindle-shaped manubrium, lacking oral tentacles, having marginal tentacles reduced to mere stubs, and being very short-lived (surviving for a few hours at most). Gonads develop in medusa buds while they are still attached to the hydroids, and gametes are shed either prior to liberation of the medusae or shortly thereafter. The eggs are surrounded by an envelope bearing nematocysts (heterotrichous microbasic euryteles). The cnidome of both hydroid and medusa stages consists of desmonemes and heterotrichous microbasic euryteles. The diagnosis of the genus Bougainvillia is modified to accommodate this new deep-water species.

鮪はえなわの漂移から得た掃海区域について(日本航海学会第32回講演会)

Long lining is the best method for catching tuna at a depth of 80 to 180m. Construction of the fishing gear is shown in fig.1. 2. The principal items are main lines (cotton or nylon yarn), branch lines (cotton or nylon yarn) and hooks. Auxiliary tools are buoy lines, buoys (glass balls), bamboo rods. A set of unit line is 200 to 400m. long, with branch lines about 10 to 20m. long. The depth of hooks is adjusted by the buoy line to meet the swimming shoals. About 4a.m. we start the work. The unit lines are joined, hooks are baited with frozen sauries, and sets are cast into the sea from her stern with the speed about 8 kts. The work is continued till about 8a.m. After the work was finished, the boat drift there about 4 hours. About 11a.m., we commenced to haul the lines toward the end, and continue this work 12 hours. About 11p.m. all finished the work. During the work long lines drift off by current. When the fishing gear drift freely without foul, we can consider that the depth of the sea is more deeper than the depth of the fishing gear.

Lampris regius (Bonnaterre), the Opah or Moonfish from the North Pacific

THE capture of a moonfish, Lampris regius (Bonnaterre) off the coast of Alaska is believed to greatly extend the known range of this species in the northeastern Pacific. This fish was taken on long-line halibut gear of the halibut vessel Bernice, Captain Louis Sunde of Seattle, on September 21, 1935, 30 miles S. X E. /2 E. off Icy Bay, Alaska, approximately 590 24' N. Lat., 1410 42' W. Long. The depth of water was about 125 fathoms. This specimen was caught at or above a depth of about 50 fathoms due to snarling of that portion of the gear by the glass floats of the buoy line.