Some updates to the method for calculation of parameters of bottom trawl system

The method for calculation of geometric parameters of trawl system proposed by F.I. Baranov is analyzed. The calculation includes evaluation of spacer force and drag for all elements of trawl system and solution of transcendental equation to find a distance between the otter boards of bottom trawl. Special attention is paid to considering and enhancement of common techniques for determining force and geometric parameters of some elements of trawl system, with identifying the most appropriate ways. The calculations and experimental data are compared for a trawl system using the Scanmar equipment for monitoring of fishing gear. The updated model simulates more adequately the forming of bottom trawl geometry, therefore it can be used for assessment of the catch area during trawl surveys conducted by bottom trawls

Some aspects of pot fishery on humpback shrimp <i>Pandalus hypsinotus</i> and its biological condition in the southern part of the subzone Primorye (Japan Sea) in autumn 2013

Data on productivity of pot fishery on humpback shrimp at the coast of Primorye are presented, actual in conditions of its trawl fishery ban in the northwestern Japan Sea. Biological parameters of the shrimp in the fishing season are considered, and dynamics of the catches is analyzed for one of the major fishing grounds. Species composition and abundance of by-catch in the shrimp pots are discussed. Dependence of the shrimp catch on options of the bite preparation is determined

Assessment of natural density of distribution for fish by the catches at light stations

Algorithm for calculation of illumination produced by shipboard lights at the sea surface and underwater is developed and implemented with Microsoft© Office Excel software. The surface illumination is calculated for the fishing vessel STR-420 with the light equipment for saury fishery. Irregularity of the lighting around the vessel is shown that depends on the lamps arrangement. Optimal scheme of the lamps arrangement is proposed for a new saury trap with the catch volume > 7000 m3. The optimal arrangement provides more regular lighting and therefore larger illuminated area for attraction of fish with positive phototaxis, as saury. Relationship between natural density of saury distribution and its catch per trap is determined for this trap

Anchor system for installation of fishing gears on soft grounds

Mushroom anchors are proposed for positioning of vessels and fishing gears on soft grounds, as sands and silts. Designs of the anchors of original shape are presented. Their holding force is determined for certain navigational conditions, and the forces acting on a floating object are calculated for the cases of anchoring perpendicular and parallel to the water flow. Weight of the mushroom anchors necessary for anchoring of a floating object is calculated and scheme of the anchorage is presented for the depth 250 m. The mushroom anchors using for rescue operations in the Okhotsk Sea and for shrimp pot fishery in the Japan Sea is discussed, in particular the episode of positioning the vessel of deadweight 2433 t in conditions of 3-points roughness and the current velocity 2 knots at the sea surface and 4 knots at the sea bottom with using two stern and one bow mushroom anchors. Using of the compact mushroom anchor for shrimp pot fishery allows to reduce the traps moving along the bottom during their hauling. Possibly, the mushroom anchors could be used for other gears installation, as well, as stationary nets, crab traps, bottom longlines, etc