Impact of Brackish Water Shrimp Farming on

Agricultural Land and Surrounding

Environment in the Southwest

Coastal Zone of Bangladesh

A.F.M. Tariqul Islam1,2, Umme Kulsum Navera 2 and M. Golam Mahboob1

2 Department of Water Resources Engineering

Bangladesh University of Engineering & Technology

(BUET)

1 GIS & RS Lab, T&C Wing

Bangladesh Agricultural Research Institute (BARI)

BENJapan Webinar/Teleconference on Environment Aspects (WEA-22)

April 7, 2012

Outline of the presentation

1. Background

2. Materials and Methods

3. Results

- Impact of shrimp farming on agricultural Land

- Impact of shrimp farming on coastal environment

4. Conclusion

Coastal shrimp farming in Southwestern areas is an age old

practice

Local people used to practice traditional aquaculture

They used tidal water for aquaculture in paddy field in Jan~Jul

In 1960s govt. made polders in this coastal area which ended

traditional shrimp aquaculture for few years

After 1970, strong international market demand and high prices

encouraged farmers to resume shrimp farming in polders

Rice cultivation no longer financially viable to due to salt water-

logging

These two factors together worked as a catalyst to the process of

accelerated shrimp farming

Background

Rapid expansion of shrimp culture caused rising concern due

to its adverse effect on the coastal environment

It is damaging the traditional agricultural systems and

unbalancing the socio-economic scenarios of the affected

areas

Fig. Map of coastal zone showing main shrimp farming upazila

To find out the trend of agricultural land encroached

due to increasing shrimp farming

To find out the impacts of increasing Shrimp Farming

on surrounding environments

Objectives

• Kaligonj upazila, Satkhira district, Bangladesh

• between 22º 21' to 22º 33' N and 88º 58' to 89º 10' E

• brackish water area of south-western part of Bangladesh

Study Area

Study Area

Types of data Year Source

Landsat MSS 09 Feb, 1977

SPARRSOLandsat TM 14 Nov, 1990

Landsat TM 4 Nov, 2004

Fresh water area 11-20 November, 2008 GPS survey

Environmental data 11-20 November, 2008 Questionnaire

survey

Data used

Trend analysis

Find out types of Environmental

Impact

Report

Conduct Questionnaire

Survey

Extract Area statistics

Processed and Classified images Landsat MSS 1977 andTM 1990, 2004

Methodology

RS and GIS data used for monitoring developmentshrimp farming during 1977 to 2004

A survey was carried out using GPS to locatefreshwater fisheries area.

The land use status for actual brackish water shrimpfarms, crop land, water bodies and settlement areaalong with its changing trend from the year 1977 to2004 were calculated

A total of 99 respondents were interviewed from thisupazila with a preset open ended questionnaireinterview schedule

Then the local peoples’ perception was observed tofind out the types of environmental degradation dueto shrimp farming

Procedure

Results & Discussion

A. Impact of shrimp farming on agricultural land

Fig: Satellite and Classified Images of Kaligonj upazila, 2004

Comparison changes of major land use classes

0

5000

10000

15000

20000

25000

Are

a (

ha)

Shrimp

Cro

p Lan

d

Water

Settl

emen

t

Land use change pattern between year of 1977 and 2004

Upazila: Kaligonj1977 1990 2004

Results & Discussion

Changes in Agricultural Land and Shrimp Farming

-15000

-10000

-5000

0

5000

10000

15000

1977-1990 1990-2004

Are

a (

ha)

Agricultural Land Shrimp Farm

RS data indicated that the agricultural land decreased gradually only

due to increase of rapid expansion of brackish water shrimp farming

as other land uses remaining almost the same

Results & Discussion

The survey results showed that the people’s

perception about environmental degradation due to

increasing saline water shrimp farming were:

increasing salinity both in soil and water

decrease land fertility

health hazards

loss of biodiversity

water scarcity etc.

B. Impact of shrimp farming on environment

Major causes of increasing salinity due to Shrimp

Farming (SF)

% of

responses

Unplanned expansion of bagda gher caused salinity 24.86

Ghers contaminate adjacent land through seepage. 23.16

Shrimp farm caused salinity increase in ground water 17.51

Shrimp farming caused water logging problem 15.25

Saline water in the rivers and canals caused land salinity 14.12

Adding extra salt into the water to ensure better growth

of shrimp

5.29

Total 100.00

(i) Effects of shrimp farming on salinity

Map showing max. soil salinity in 1973 and 2000 in coastal zone

Source: SRDI 2000Source: SRDI 1973

ii. Effects of shrimp farming on land fertility

Major causes of decreasing land fertility

due to SF

% of total

responses

Salinity due to shrimp farming reduce yield

capacity30.92

Shrimp farming decreased fruits and

vegetables production27.63

Excess use of chemicals in shrimp farming

reduced yield of crops23.68

Shrimp farming reduce the organic matter 17.76

Total 100.00

iii. Effects of shrimp farming on health hazards

Major causes of health hazard due to SF % of

responses

Shrimp farming increased epidermis diseases 20.56

Increased risk of malnutrition to common

people

18.22

Shrimp waste disposal directly to environment

without treatment

17.76

Health hazards due to unhygienic shrimp

processing

15.89

Increased mosquitoes which consequent

disease

14.48

Shrimp farming caused gastro-intestinal

diseases

13.08

Total 100.00

iv. Effects of shrimp farming on Biodiversity

Major causes of loss of biodiversity due to SF % of

Responses

Shrimp farmers destroyed habitats for wild

animals, birds , etc.

28.25

Decreased livestock due to shrimp farming 27.68

During collecting shrimp fry, fish and all other

species are destroyed

23.16

Expansion of shrimp farming caused decrease

the native fishes like Rui, Katla

19.21

Shrimp farmers killed some local animals: frogs,

crabs etc

18.64

Total 100.00

v. Effects of shrimp farming on Water scarcity

Major causes of water due to SF Responses

(%)

Fresh water pond decreased due to gher

expansion

25.00

Water pollution due to excess use of

chemical used in shrimp farm

20.92

Scarcity of irrigation water due to shrimp

farming

19.89

Hand tube wells are out off order or

produce saline water

18.37

Ground water contaminated due to shrimp

farming

15.82

Total 100.00

Source: UNEP, 1999

women and school going

children are to walk a

long distance look for

available filtered water or

non saline tube–wells or

ponds.

The major findings of this study are stated as follows:

(1) During 1977 there was no shrimp farm whereas in 2004

shrimp farming area encroached 36.44 percent of

Kaligonj upazila

(2) The satellite images data provided the information that

the shrimp farming areas have encroached the

agricultural land mainly

(3) The peoples’ perception showed that the study area

experienced serious environmental degradation due to

unplanned expansion of brackish water shrimp farming

(4) Proper planning, regulation and motivation are needed

to develop an environment friendly shrimp farming to

avoid ecological disasters in the coastal zone

Conclusion