Project Title: Study of Tuna Fishing Ground Condition in the Eastern Indian Ocean

Project Duration: 3 years (from 2001 to 2003)

Project Justification:

Over fishing is seem to be the current situation for fisheries in the EEZ area of Southeast Asian region. In order to aware for the food security of the region, SEAFDEC/TD try to promote the Purse seine and long line Tuna as gears for the High Sea which is the under utilize resource area to the region. The large stock of Tuna in the high sea could be able to attract fisherman and decrease fishing activities in the EEZ area. Every year, since 1994, MV. SEAFDEC vessel has operated Tuna purse seine and longline demonstration in the Eastern Indian Ocean in order to promote High sea fishing to the region.

For High sea fishing, knowledge in the relationship between oceanographic and meteorological parameters and catch are important for fishing success in term of catch ability, time and fuel consuming for fish searching. Therefore, the study on fishing ground condition is needed to do in the parallel with every Longline and Purse seine Tuna operation.

The project was planed to collect oceanographic data, meteorological data and catch data from Tuna purse seine and Longline demonstration on MV.SEAFDEC vessel which is a part of training course in SEAFDEC training department from 2001-2004 and to request related data such as ocean color, sea surface temperature from concerning data center. The data will be a part of long term continues data collecting since 1994 for finding out some appropriate oceanographic and meteorological parameter that can be an index for fish abundance in the area.

1. Field survey

Study area: Eastern Indian Ocean

The oceanographic (temperature, salinity, dissolved oxygen, depth of thermocline, ocean color, chlorophyll maximum depth, current) and meteorological (wind) data collection can be divided into four categories

1. Data collecting during cruising

On the way cruising to the fishing ground and searching for drifting object and Fish Aggregating Devices (FADs), some oceanographic and meteorological data will be collect by:

1. Navigation logsheet

The navigation officer on duty will be requested to record wind, current and sea surface temperature data on navigation logsheet every one hour all over the cruise period.

2. Surface Water sampling

Every 6-hour interval in the study area, about 10-liter of sea surface water will be collected using pump. The water sample will be measured Chlorophyll-a concentration by standard method of seawater analysis using spectrophotometer. This data is for the validation purpose with ocean color data from remote sensing.

3. Expendable Bathythermograph probe (XBT)

XBT will be used to collect temperature and thermocline depth data at every one-degree square resolution of the study area that don?t have oceanographic station.

4. Sea surface temperature from NOAA AVHRR receiving on board MV.SEAFDEC


2. Data collecting during ship drifting

In this project the oceanographic station will not fix but depended on the fishing activity. Before the fishing operation, oceanographic exploring will be done as follow:

1. Using Integrated temperature salinity and dissolved oxygen instrument (ICTD) for collecting in situ temperature, salinity, dissolved oxygen and fluorescence data from surface to about 700 meter
2. Water sampling by Niskin bottle at about 5 to 12 standard depth from surface to 700 meter. The water sample will be determined dissolved oxygen by Winkler titration procedure and chlorophyll-a by spectrophotometer.
3. Water transparency and light intensity will be measure by Sechi disc and quantum meter respectively.

3. Data collecting from the part of fishing practice

1. Data, time and position during FADs setting and arriving will be recorded for estimation current speed and direction
2. Catch data

• CPUE
• Catch and size composition ( for purse seine, sampling from the first scoop net for transferring from net to fish hold)

1. Data will be requested or downloaded from concerning data center

1. Chlorophyll-a data from SeaWiFs
2. Sea surface temperature from NOAA AVHRR

Principle investigators:

Penjan Laongmanee

Siriporn Pradit

Natinee Sukramongkol