The catch survey is conducted on nine target fishing gears in 22 provinces, which are located along the sea. The samplings cover all annually registered fishing units of nine fishing gears. One fishing unit means a fishing household with fishing gear and fishers. The sampling technique used is stratified random sampling with type of fishing gear as strata. This technique is also applied in fishing effort analysis. The proportion of samplings of each stratum is as follows:
Table 1. App. III Percentage of each stratum sampled for nine different fishing gears
Type of gear |
Boat length |
Percentage of total fishing units |
Otter board trawl | ||
boat length < 14 m |
10 | |
boat length 14-18 m |
10 | |
boat length 19-25 m |
10 | |
boat length > 25 m |
15 | |
| Pair trawl | ||
boat length < 14 m |
30 | |
boat length 14-18 m |
10 | |
boat length > 18 m |
15 | |
| Beam trawl | All |
30 |
| Purse sein | All |
10 |
Anchovy purse seine |
All |
10 |
King mackerel drifting gill net |
All |
10 |
Mackerel encircling gill net |
All |
15 |
| Push net | All |
15 |
Deep water set net |
All |
15 |
The analysis is first monthly done by group of fishing gear, species, and province, after that each result is summed up to the annual total production. The equations for analysis are as follows:
For fishing gears that are not surveyed by length of boat
Th | = |
| |
When | Th | = | total catch by type of fishing gear in month h |
N | = | number of total fishing units | |
n | = | number of samples | |
Xhi | = | catch of sample i in month h | |
h | = | month 1, 2, 3,…, 12 | |
i | = | sample 1, 2, 3,…, n | |
|
| ||
For fishing gears that are surveyed by length of boat (otter board trawl, pair trawl)
Thj | = |
| |
When | j | = | group by length of boat, 1, 2, 3, 4 for otter board trawl, and 1, 2, 3 for pair trawl |
Thj | = | total catch of fishing unit in month h of group j | |
Nj | = | number of total fishing units of group j | |
nj | = | number of samples of group j | |
Xhij | = | catch of sample i of group j in month h | |
|
| ||
|
| ||
The catch survey is conducted on target fishing gears, which are all types of fishing gears except the nine fishing gears of LSF mentioned above, in 22 coastal provinces. Then the target fishing gears are as follows:
The sampling technique used is stratified stage sampling that the first stage is to divide marine fishing communities into five fishing zones by provinces as follows:
|
Zone 1: Trad, Chanthaburi, Rayong; Zone 2: Chonburi, Chachoengsao, Samut Prakan, Samut Sakhon, Samut Songkhram, Petchaburi, Prachuap Khiri Khan; Zone 3: Chumphon, Surat Thani, Nakhon Si Thammarat; and Zone 4: Songkhla, Pattani, Narathiwat |
Each zone is divided into 2 strata, A and B. The stratum A is fishing communities having boats more than 100 units, while having boats less than 100 units for stratum B. Fishing community samplings are conducted by using proportion of each stratum. The total samples will be 400 fishing communities.
For the second stage, the small-scale fishing gear survey is conducted by census in fishing community samples of each stratum. At least five fishing households of each fishing gear are sampled for catch data. The equations used for production and value analysis are as follows:
| = |
| |
| = |
| |
When | Xhijk | = | catch of household k, fishing gear j, fishing community i of zone h |
Yhijk | = | value of household k, fishing gear j, fishing community i of zone h | |
h | = | fishing zone 1, 2,…, 5 | |
i | = | fishing community 1, 2,…, n | |
j | = | fishing gear 1, 2,…, r | |
k | = | fishing household 1, 2,…, m | |
N | = | number of total fishing communities | |
n | = | number of fishing community samples | |
M | = | number of total fishing households in fishing community sample | |
m | = | number of total fishing household samples | |
And |
| = | total catch of each fishing gear in each fishing zone |
| = | value of each fishing gear in each fishing zone | |
So |
| = |
|
| = |
| |
When |
| = | catch of all fishing gears in each zone |
| = | catch of all fishing gears in each zone | |
And |
| = |
|
| = |
| |
When |
| = | total catch of all fishing gears in all zones |
| = | total value of all fishing gears in all zones |
55 (DoF, 2006f).
56 (DoF, 2006b).
