| Type |
Proceedings paper |
| Date |
2000 |
| Language |
English |
| Author(s) |
Kakuma S1 |
| Affiliation(s) |
1 : Okinawa fisheries experimental station 1-3-1 Nishizaki, Itoman |
| Meeting |
Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 |
| Keyword(s) |
Attracting techniques, Catch/effort, Current data, Data buoys, Tuna fisheries, Article Geographic Terms: ISEW, Japan, Nansei Shoto, Okinawa |
| Abstract |
Yellowfin tuna (Thunnus albacares) is a main target for the fisheries at Fish Aggregating Devices (FADs) off the south of Okinawa island. Catch and weight composition of the tuna were monitored at a fisheries cooperative market from 1989 to 1998. Some distinct weight groups (considered to represent cohorts) appeared in the catch and the weight of these groups increased monthly - presumably as individual tuna grew. Although small, light weight fish were caught year-round, the 2 kg weight group that was recruited in May grew to about 15 kg by May of the next year. There was a significant seasonal cycle in the monthly catches. The catch of heavier weight groups decreased in winter indicating the tuna moved out of this FAD area. At one of huge FADs (Nirai), fifteen nautical miles southeast of Okinawa island (depth about 1.300 m), a current meter (Aanderaa RCM-7) recorded current and water temperature from June 1995 to March 1996. The current meter was attached to the FAD at 4 m depth. When typhoons attacked Okinawa, the water temperature drastically dropped. Typically, average current speed was 29 cm/s and eastward current was most frequent. Being affected by tide, the current was averaged over twenty-five hours. Current speed was correlated with the yellowfin catch in 120 daily sets at the FAD; the weaker the current speed, the greater the catch. Although not significant, the catch was greater with northeastward current than with southwestward current. |
| Full Text |
| File |
Pages |
Size |
Access |
| 12662.pdf |
10 |
362 KB |
Open access |
|
