Methodology of Evaluating Selectivity Performance - Two Selective Processes of Trawl Sorting Devices: Fish Encountering and Being Sieved

The mesh selectivity of each mesh size is a basic study for size-sorting, and usually expresses the proportion retained as a function of the body length of a fish. It is however likely to depend more directly on the relationship between the girth of fish and mesh perimeter whether a fish can pass through a mesh. Selectivity curves sm(G / p) fitted to some experimental data in terms of the ratio of girth G to mesh perimeter p coincided closely for several species of different body shape. This means that geometrically similar combinations of mesh perimeter and girth have the same selectivity, and also suggests that a master curve based on girth to mesh perimeter allow estimation of the selectivity curve with girth-length relationship. The master curve analysis method is useful in particular for multi-species trawl fishery in tropical and sub-tropical areas. From the Nordmore grid fishing experiments, the grid had size-selectivity by barspacing in the similar as well as codend mesh selectivity. As far as grids have size-selectivity as a sieve process, sorting efficiency must depend not only on barspacing but also on length distributions of each species, and therefore the appropriate bar-space should be determined for sorting. The master curve analysis method can be applied to grid selectivity (proportion of fish retained by the grid). Sieving process of sorting device like grid and square mesh window panel is valid only for fishes encountering it. Another point in the sorting efficiency is the encounter probability defined as a proportion of a fish encountering the sorting device

Methodology of evaluating selectivity performance - two selective processes of trawl sorting devices: Fish encountering and being sieved

The mesh selectivity of each mesh size is a basic study for size-sorting, and usually expresses the proportion retained as a function of the body length of a fish. It is however likely to depend more directly on the relationship between the girth of fish and mesh perimeter whether a fish can pass through a mesh. Selectivity curves sm (G / p) fitted to some experimental data in terms of the ratio of girth G to mesh perimeter p coincided closely for several species of different body shape. This means that geometrically similar combinations of mesh perimeter and girth have the same selectivity, and also suggests that a master curve based on girth to mesh perimeter allow estimation of the selectivity curve with girth-length relationship. The master curve analysis method is useful in particular for multi-species trawl fishery in tropical and sub-tropical areas. From the Nordmore grid fishing experiments, the grid had size-selectivity by barspacing in the similar as well as codend mesh selectivity. As far as grids have size-selectivity as a sieve process, sorting efficiency must depend not only on barspacing but also on length distributions of each species, and therefore the appropriate bar-space should be determined for sorting. The master curve analysis method can be applied to grid selectivity (proportion of fish retained by the grid). Sieving process of sorting device like grid and square mesh window panel is valid only for fishes encountering it. Another point in the sorting efficiency is the encounter probability defined as a proportion of a fish encountering the sorting device

CATCHABILITY DIFFERENCE OF GILL NET AND COLLAPSIBLE BAITED POT FOR JAPANESE ROCK CRAB

The objective of this experiment is to know the catchabjlity of gill net and collapsible baited pot on Japanese rock crab. Result shows that gillnet caught more than twenty species other than Japanese rock crab

2000-2001年の太平洋西部海域におけるプラスチック微小片の分布

Sampling was conducted at 31 sites in the western Pacific Ocean from 2000 to 2001 with the aim of collecting plastic fragments with a neuston net (mesh size: 1.00 mm × 1.64 mm). Small plastic fragments including microplastics (small fragments in the size range of 1.1–41.8 mm) were collected at multiple survey sites. Waters with high densities of small fragments were observed between 20°N and 30°N to the south of Japan and between 20°S and 30°S to the northeast of New Zealand (maxima of 6.63 × 102 and 2.04 × 102 pieces/ha, respectively). These waters are located to the west of the Ekman convergence zones related to trade winds in the subtropical gyres of the North and South Pacific Oceans. Nearly no small plastics were observed in the tropical circulation of the western Pacific Ocean.2000年から2001年にかけて太平洋西部海域の31地点でニューストンネット（目合1.00mm×1.64mm）によるプラスチック微小片の採集を行った。マイクロプラスチック(5mm以下)を含むプラスチック微小片は，日本の南の北緯20—30度の海域とニュージーランド北東の南緯20—30度の海域で高密度に採集され（各々最高で6.63×102と2.04×102個/ha），これらの海域は北太平洋と南太平洋における亜熱帯循環内の漂流物収束帯の西端に位置する。赤道付近の熱帯循環内の採集点ではほとんど採集されなかった

Importin-β and the small guanosine triphosphatase Ran mediate chromosome loading of the human chromokinesin Kid

Nucleocytoplasmic transport factors mediate various cellular processes, including nuclear transport, spindle assembly, and nuclear envelope/pore formation. In this paper, we identify the chromokinesin human kinesin-like DNA binding protein (hKid) as an import cargo of the importin-α/β transport pathway and determine its nuclear localization signals (NLSs). Upon the loss of its functional NLSs, hKid exhibited reduced interactions with the mitotic chromosomes of living cells. In digitonin-permeabilized mitotic cells, hKid was bound only to the spindle and not to the chromosomes themselves. Surprisingly, hKid bound to importin-α/β was efficiently targeted to mitotic chromosomes. The addition of Ran–guanosine diphosphate and an energy source, which generates Ran–guanosine triphosphate (GTP) locally at mitotic chromosomes, enhanced the importin-β–mediated chromosome loading of hKid. Our results indicate that the association of importin-β and -α with hKid triggers the initial targeting of hKid to mitotic chromosomes and that local Ran-GTP–mediated cargo release promotes the accumulation of hKid on chromosomes. Thus, this study demonstrates a novel nucleocytoplasmic transport factor–mediated mechanism for targeting proteins to mitotic chromosomes

The current state of marine debris on the seafloor in offshore area around Japan

Marine debris on the seafloor has not been thoroughly investigated, and there is little information compared to other types of marine debris. We conducted bottom trawl surveys to determine the present situation of marine debris on the seafloor in offshore areas around Japan. The survey was conducted in three sea areas with different characteristics. As a result, it was found that the amount of marine debris in submarine canyons (2926.1 items/km2) was higher than on the continental shelf. It was revealed that most marine debris on the seafloor is comprised of plastic products, and that debris on the seafloor retains its condition for a long time (over 30 years) without deterioration. In addition, the type of marine debris is affected by the industries operating in each area. Continuing to investigate marine debris on the seafloor in more areas will contribute to solving the problem of marine debris