May 15, 2009

Ca Mau rainy season

It is good to have new flow-meter before going to Ca Mau. The flow-meter looks like a rocket with 6 digits counter inside


The follows are several steps of using it that I tried to find by myself (they provided a not very good manual in deed):
1. Open the screw at back side, inject tap water in to the flow meter, and tighten the screw again.
2. Use a long string to tie one side to the flow-meter, and the other side to a tree or somewhere firmly if you don’t want it swims away.
3. Read the current number on counter, write down the number or just remember if you can.
4. When everything ready, looking your watch and start putting the flow-meter in to water.
5. Make sure the head of flow-meter facing to current direction.
6. After a time, 10 minutes for example, pull up the flow-meter out of water.
7. Read the new number in the counter.
8. Take the difference between new and the last number of the counter.
9. Calculation: The SPEED in cm/sec = Distance in meters multiple (X) 100 and divide (/) Time in seconds.
In that Distance in meters = Difference in COUNTS multiple (X) Rotor Constant and divide (/) 999,999.
And Rotor Constant = 26,873
10. Open the screw to get water out, clean, dry, and put to box for the next using.
So now you know how to get water current speed data :)).

The Spot image also arrived before the trip, so I have it for sites selection. The image was taken on 10 March 2008; resolution is 2.5m, and no cloud. It can be used first for trap sites in mangrove selection, and other purposes later.


Four selected sites at Tan An commune


Four selected sites at TGD commune

It starts rainy season, I've got wet all the time. Camera, laptop, papers…were covered with layers of plastic. Anyway, I have found out new sites for the next experiment. There are 4 sites (yellow dots) for each commune:
- close to shrimp farm and close to river,
- close to shrimp farm and in the forest,
- far from shrimp farm and close to river,
- far from shrimp farm and in forest (see map)
Catch in traps will be collected 8-10 days a month (the days water getting in the forest)
The purpose of this design is trying to answer the questions; what is different of catch between the area close to shrimp farm and far from it; and what is different of catch between the areas close to river and in deep mangrove? We would know the differences of catch between disturbance and undisturbance areas; we also would know the differences of fish/shrimp species between close to river and in deep mangrove.

This trip I involved four more river barrier fishermen for logbook recording. These four river barriers located more in land and close to shrimp farms. Lucky that all of them happy to join the program. But I am still not sure if they can record good data or not. Interesting is people said that river barriers which close to shrimp farm have better catch compare to river barriers close to forest. The reasons are: tiger shrimp escape from shrimp farms, then caught by the barriers, and more inland barriers located far from each other.

I am happy because this time I collected a good secondary data. Mr. Do Chi Sy, head of Fisheries Resource Protection Department let me copy all Ca Mau Fisheries Ms. Access Database and related documents in digital format. So now I can find the Ca Mau fisheries data back to 1989. He also gave me the 2007 province Statistical CD, so I don’t have to go to Statistical Department to buy.


You can enjoy with us some fieldwork activities:


Setup net in the rainy forest, cod-end


Setup net in the rainy forest, entrance


Fish samples storing lab at fishermen house, Mr. Huynh Van Lap


Fish samples storing lab at fishermen house, Mr. Ly Van Loc


Relax time


Going to the forest


Illegal forest cut. Mr. Hung, a border guard, he still found no way to stop this illegal activities, his duty anyway.


Illegal forest cut. The “pirates” put the cut down mangrove everywhere and waiting for suitable time to take out of the forest.


Still beautiful forest

1 comment:

  1. Excellent, very nice pictures and instructive
    Nghia

    ReplyDelete