Studies on the Invluence of fishery wastes of Fish Behavior and the Develpment of Technology to remove the Wastes from the Seabed

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13680653
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 環境保全
• Research Institution: Nihon University
• Principal Investigator: YOSHIHARA Kiyoshi Nihon University, College of Bioresouce Sciences, Professor, 生物資源科学部, 教授 (10059800)
• Co-Investigator(Kenkyū-buntansha): KOJIMA Takato Nihon University, College of Bioresouce Sciences, Professor, 生物資源科学部, 助教授 (60205383) ; SUGITA Haruo Nihon University, College of Bioresouce Sciences, Professor, 生物資源科学部, 教授 (50139052) ; TANIUCHI Touru Nihon University, College of Bioresouce Sciences, Professor, 生物資源科学部, 教授 (00012021)
• Project Period (FY): 2001 – 2002
• Keywords: Fisheries Wastes / Development of Technology to move / Takada bank of Sagami nada / Verical long line fishery / Deep sea Underwater Camera / Annulus liked matter / Bacteria flora

Research Abstract

In 2002, we investigated on the efficiency of tools for recovering wasted fishing gears, such as fishing lines, hooks and sinkers that were used for deep-sea fishing, from the floor of the sea. We reported that the most efficient tool was the one which uses a stainless steel rod, 12 mm in diameter, to which hook-shaped metal rods are welded (Type IV).
In 2003, the Type IV was improved by lengthening the stainless steel rod to 2 m. We also shortened the length of the Type IV to 1 m for better maneuverability. The two modified models were tried separately on an actual fishing ground. Though the conditions of the tried area for the two models were different in terms of the current, wind, etc., we observed that the 2 m model was more efficient in catching the wastes than the 1 m model. Many of the collected wastes had various organisms with hard calcareous shells attached on them. The deep sea video camera set at the fishing ground showed that the wastes have become part of the ecosystem on the seabed.
The wastes were collected around the summit of a high ground of the seabed. The amount of wasted collected was larger in the area toward northeast from the summit than the area toward southwest. In the area toward northeast, the amount of wastes collected was higher near the summit than that of away from the summit. In the area toward southwest no such difference was observed in the amount of wastes collected. As a whole, the amount of wastes collected was larger near the summit of the high ground than that away from the summit.
In order to find out the effect of wastes on fishes, we kept fishes in a tank which contained the various wastes that we collected from the seabed, but the behavior of the fishes did not appear to be affected by the presence of such wastes in the tank.
We used the section of the seashells that have been attached to the wastes to determine how long ago the wastes have been discarded. We were able to observe clear growth patterns n the section of the shells.
We also found and identified 54 families of bacteria on the wastes we collected from the seabed.