Identification of plant genetic resources affected by shrimp farming in the southwestern coastal region of Bangladesh

The main purpose of the study was to identify the plant genetic resources (PGRs) affected by shrimp farming and to determine their magnitude of vulnerability. Data were collected from randomly selected 100 respondents, through personal interview, using an interview schedule, at Dumuria upazila of Khulna district, during 16 November 2009 to 15 February 2010. The fruit PGRs were more affected by shrimp farming than that of timber yielding and other types of PGRs. Among the 18-fruit PGRs available, all were endangered, except indigenous velvet apple, Diospyros peregrine (Gaertn.) Gürke, which was in threatened condition. Among the fruit species, banana, Musa acuminate; guava, Psidium guajava L.; jackfruit, Artocarpus heterophyllus Lam.; sapota, Manilkara zapota L. and betel nut, Areca catechu L. were in highly endangered. Among the 17-timber yielding and other plant species, only 7-PGRs were affected by shrimp farming while majority (10-PGRs) had been available in different extents. Among the vulnerable PGRs, bamboo, Bambusa bambos (L.) Voss; flame of the forest, Delonix regia (Boj. ex Hook.) Raf.; teak, Tectona grandis L.f. and banyan, Ficus benghalensis L. were endangered, while Indian ash tree, Lannea coromandelica (Houtt.) Merr.; ipil-ipil, Leucaena leucocephala (Lam.) de Wit and cool mat, Schumannianthus dichotomus (Roxb.) Gagnep. were in threatened condition. In general, the total fruit trees decreased in numbers (-74.17%) after inception of shrimp farming. On the other hand, the total numbers of timber yielding plants increased by 15.45%. From the overall consideration (irrespective of types), the number of plant population decreased (58.10%) after inception of shrimp farming. It means that the plant species were affected by shrimp farming and became endangered.


Introduction
Bangladesh, being an agro-based country and having a vast fertile plain land, has not yet achieved a sustainable self-sufficiency in food production. Like other essential commodities, it is importing a large quantities of food grains every year to meet up its food shortage. However, a few agricultural, industrial and fisheries products are being exported; of which freezing shrimp is one of the major components (Paul, 1996). In Bangladesh, the sectorial contribution by shrimp export to the GDP was 8% in 1996-97 while the same was 6.97% in 1997-98 (Anonymous, 1998. The foreign earnings by crustaceans, which include shrimp, were 12.8% in 2015-16 increased to 13.56% in 2016-17 (Anonymous, 2019. Besides, shrimp farming is one of the fastest growing components of the global aquaculture. In 1988, the world's shrimp farmers produced 7,37,000 tons of shrimp worth of an estimated USD 6 billion (Rosenberry, 1998). The culture of shrimp has become very much popular at the coastal region of the country, considering it as a unique means of income generation. This popularity has come from its high economic return.
The shrimp culture is locally termed as 'gher' [the water-bodies of shrimp/prawn farm are known as "gher" (Akter et al., 2019)] located mostly at the southwestern part of the country (southern part of Satkhira, Khulna and Bagerhat districts). The shrimp culture/gher business has become blessings for a small segment of our population, but a curse for the vast majority. The few beneficiaries are almost property owners who can afford a lot of money, because it requires high initial investment. This includes taking land lease from the farmers, making embankment around the land, erection of a number of small cottage for night guard, recruitment of support service personnel, purchasing of post larvae (daughter shrimp) and other miscellaneous costs. The cultural procedure at first involves in making embankment around the land and then the whole area of land is filled up by the saline water from the river, which acts as cultural media for growth and development of post larvae (Paul, 1996). This artificial stagnant of saline water in a particular area of land creates enormous problems on normal life of poor village dwellers. Firstly, the land becomes uncultivable for usual crop plants. Secondly, the vast land is occupied by water, so, the cattle's do not get grassland and ultimately the cattle owners become compelled to sell their cattle, as a result, cow's milk become unavailable. Thirdly, the village dwellers generally use cow dung and paddy residues as a cheap means of fuel, but at present, due to its unavailability, they become dependent on costly firewood. Fourthly, saline water does not retain within a confined area, percolation and seepage of water takes place which create another major problems to the existence of fruit and valuable trees and also leading to the extinction of fresh-water fish, including aquatic animals and plants in the small ponds of poor village dwellers. Paul and Vogl (2011) addressed that shrimp farming environmental impacts such as mangrove degradation, salt-water intrusion, sedimentation, pollution and disease outbreaks had been found to be obstacles for the sustainable development of farming. In this way, shrimp culture creates a direct threat to the existence of poor families in the area, and makes a natural and/or ecological imbalance (Karim, 2000).
Considering these viewpoints, an attempt was made to conduct a study entitled "Identification of Plant Genetic Resources Affected by Shrimp Farming in the Southwestern Coastal Region of Bangladesh" to i) describe the socioeconomic characteristics of the respondents; ii) identify the PGRs' availability in the study area; and iii) determine the extent of vulnerability of PGRs caused by shrimp farming.

Methodology
The research was designed to identify the PGRs as affected by shrimp farming and to investigate the extent of vulnerability of the PGRs caused by shrimp farming. The two main centers of shrimp production are located at (a) Khulna, Satkhira, Bagerhat districts in the Southwest; and (b) Chittagong and Cox's bazaar districts in the Southeast. Rahman et al. (1994) highlighted that about 80% area of Khulna, Bagerhat, and Satkhira are under shrimp culture in Bangladesh, and noticed a threefold increase in the last decade. The area under shrimp culture had increased from 52,000 ha in 1982-83 to 141,000 ha in 1999-00, and about 75% of this land is located in the Khulna, Bagerhat and Satkhira districts in the southeastern region of the country (Mazid, 2002). It now covers about 1,45,000 hectares of land sprawled over 9,000 farms, 18% of total farms. In Bangladesh, shrimp cultivation has been spreading in the coastal regions. Fourteen southern administrative districts are sharing the whole shrimp cultivation coverage. For this study, Dumuria upazila (sub-district) under Khulna district was purposively [as this was an epicenter of shrimp farming] selected as the locale of the study.
The key role-playing members of the farmer's family were selected for answering. The researchers, when went to collect data, asked the farmers whether there is any PGRs in his homestead or not. If the answer was yes (i.e., they have owned PGRs), the individual was selected as sample of the study. In this way, 100 respondents were selected by simple random sampling method. The distributions of sample farmers in the selected unions (smallest administrative unit) are shown in the Table 1.  (2017) reported that, in parallel with the significant contribution of the shrimp sector to the local and national economy, it has caused some negative impacts on local ecosystems. Ecological impacts include some deterioration of soil and water quality, depletion of mangrove forest, decrease in population of native fish and shellfish species, intrusion of saline water, water pollution and changes to local hydrology. This proves that the scenario of degradation is still worsening. The collected data were cross checked by focus group discussion (FGD).
Data were collected on some of the selected characteristics of the respondents such as age, education, family size, farm size, annual income, farming experience, agricultural knowledge, organizational participation, cosmopolitanism, training and extension media contact. Data were also collected on PGRs as affected by shrimp farming and their extent of vulnerability. The respondents were asked directly to provide information regarding the PGRs available at their homestead before and after inception of shrimp farming. The extent of vulnerability was determined by three points rating scale developed by Ahmed (2003).
Rating scale based on nature of vulnerability Percent of vulnerability Threatened ≤50 Endangered 51-99 Extinct 100 Threatened means species still abundant in its natural range but is declining in number likely to become endangered, where endangered means species having so few in number that the species could soon become extinct overall or most of its natural range while extinct means the loss of an entire species (Ahmed, 2003).
An opposite scale was also followed to observe the availability of PGRs in the study area as developed by Ahmed (2003). The scales are as follows: Rating scale based on nature of availability Percent of availability Fairly available ≤50 Moderately available 51-99 Extremely available 100 After completion of survey, all the interview schedules were compiled for processing of data. At the beginning of the data processing, all the qualitative data were converted into quantitative form by means of suitable code and score whenever necessary. Local units were converted into standard units. In several paradigms, indices and scales were constructed through the simple accumulation of scores allocated to individual or pattern of attributes. Statistical Package for Social Sciences (SPSS) was used to analyze the data. Statistical treatment such as number, percent, range, mean and standard deviation were used to describe and interpret the results.

Socioeconomic characteristics of the respondents
Majority (62%) of the respondents belonged to middle aged (36-50 years) group followed by old aged (˃50 years) group (24%) and only 14% of the respondents belonged to young aged (≤35 years) group. Average age of the respondents was around 45 years ( Table 2). The highest numbers of respondents (34%) were in the primary level (1-5 years of schooling) of education followed by secondary level (6-10 years, 31%), illiterate (14.6%), higher secondary (11-12 years, 6%) and graduate (˃12 years, 4%) level of education (Table  2). Majority (60%) of the respondents had medium sized family (5-7 members) followed by large sized family (˃7 members, 25%) and only 15% respondents had small sized family (≤4 members) ( Table 2). The average family size (6.28) of the respondents is higher than that of national average (5.6) (Anonymous, 2018), and the trend of family size is gradually lowering all over the country. It implies that the family planning activities in the study area were not so strong. The concerned department may take immediate step to create awareness among the people of the study area about planned family life. Most (85%) of the respondents were small landholders (0.21 to 1.0 ha). The subsequent respondents encircled medium land holding (1.01 to 3.0 ha, 12%) and only 3% respondents were marginal landholders (0.02 to 0.20 ha). None of them was landless (Table 2). Majority (52%) of the respondents belonged to medium income (50,000 to 1,00,000 BDT year -1 ) group. More than one-fourth (26%) of them belonged to low income group (˂50,000 BDT year -1 ) and only 22% fall in high income group (˃1,00,000 BDT year -1 ) ( Table 2). About half of the respondents (49%) had no organizational participation followed by (42%) low participation while only 9% of them had medium participation. None of the respondents had higher organizational participation ( Table 2). Most of the respondents considered to have more relation with NGO leaded Samities (group of people with same interest) than other selected organizations.
Majority (63%) of the respondents were in the category of medium cosmopolitanism while 31% were low cosmopolite and only 6% respondents were high cosmopolite (Table 2). Most (78%) of the respondents had medium scale extension media contact followed by low scale extension media contact (19%) and only 3% respondents maintained high scale extension media contact ( Table 2). The respondents were exposed to two types of training either related to crop production and/or fisheries. Highest proportion (16%) of the respondents was exposed to training related to agriculture followed by fisheries (11%)( Table 2). Most of the respondents possessed medium agricultural knowledge followed by low agricultural knowledge (9%). Only a few (4%) of the respondents possessed high agricultural knowledge (Table 2).

Plant genetic resources available at homestead of the study area
For sound living and friendly environment, it is suggested by the ecologist to cover 25% of the total land area by trees and/or other vegetation in a country. The true tree cover in Bangladesh is around 7%; but including homestead and other tree cover, it accounts around 17.4% (Rahman, 2020). Therefore, it is very essential to plant trees to increase tree cover area, which will ultimately help us for a better and healthy living.
To have an idea of tree cover in the homestead of the study area the respondents were asked to mention the number of trees available in their homesteads in different years (BISF-1989and AISF-i.e., 1999and 2009 Table 1). The most dominant plant species in the study area irrespective of time is coconut tree. The trend of number of some major fruit plant species are shown in Figure 2, which are adversely affected by salinity due to shrimp farming.
The coconut, Cocos nucifera L. tree ranked first from population point of view both in pre-project and post project time and it was followed by banana, Musa acuminate Colla; sapota, Manilkara zapota (L.) P. Royen and mango, Mangifera indica L. However, a prestigious number of fruit trees are available in the study area, but their production and growth are affected by salinity resulting from shrimp farming. In the study area, the coconut production was 70-80 drupes tree -1 year -1 in before inception of shrimp farming which was much higher than the national average i.e., 20 drupes tree -1 year -1 (Anonymous, 1998). Although the production has already reduced to 20-30 drupes tree -1 year -1 it is still higher than that of national average. Salinity along with water logging severely affected the production of fruits as well as the trees and other vegetation in the study area.    (2003).

Plant genetic resources affected by shrimp farming
Results presented in Table 3  Lam.; sapota, Manilkara zapota (L.) P. Royen and betel nut, Areca catechu L. were in highly endangered condition due to continuous intrusion of high saline water in the study area needed for shrimp farming (Table 3).
It is also observed from  Table 3 indicate that in general the total fruit trees decreased in numbers (-74.17%) after inception of shrimp farming. It means that it was affected by shrimp farming and became vulnerable (endangered). On the other hand, the total numbers of timber yielding plants increased by 15.45% after inception of shrimp farming. It means that, it was not affected except some exception and became fairly available. From overall consideration (irrespective of types), the number of plant population decreased (-58.10%) after inception of shrimp farming. It means that the plant species were affected by shrimp farming and became endangered.

Conclusion and Recommendation
The total number of fruit trees decreased after inception of shrimp farming. That means, it was affected by shrimp farming and became endangered. However, the total numbers of timber yielding plants increased after inception of shrimp farming. That means, it was not affected except some exception and became fairly available. Considering the overall scenario, the average number of plant population decreased (-58.10%), irrespective of types, after inception of shrimp farming. Thus, it might be concluded that the plant species were affected by shrimp farming and became endangered. Based on the findings, it is recommended that, indiscriminate saline water intrusion in the ghres for shrimp farming should be managed in such a way that it would not cause any harm to the existing PGRs.