Geospatial mapping of fisheries

Geospatial mapping of fisheries

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Ram Singh
[email protected]

P. K. Pandey
[email protected]

Archana Sinha
[email protected]

Central Institute of Fisheries Education
Versova, Mumbai, India

Abstract:
In the age of information and technological advancements, location awareness is becoming a key feature in management of natural resources. Geospatial mapping is a location-based study and is a part of intelligence GIS which is expected to be a useful tool for fisheries scientists, aquatic resource managers and policy planners in developing and planning strategies for fisheries resources in India. In this context, a study was performed on mapping of fisheries profile of West Bengal using GIS with critical geographic dimensions. For this purpose, fisheries data of West Bengal was accessed and integrated with different sources at district level. Data was tabulated using Microsoft Excel and then joined to digitise Map of West Bengal to enable mapping using Arc info 9.3 GIS software. This was further synchronised and integrated to generate four thematic maps based on different criteria. Map 1 contains the searchable criteria regarding the fishermen population as well as their classified categories according to their occupation. Map 2 contains fish production, fish seed production district/ wise and growth rate for 2004-2008. Map 3 contains district wise water resources and reservoir areas along with brackish water. With this mapped information, planners and various stakeholders will have readily accessible district level data on various components of fisheries of West Bengal, thereby facilitating better planning, management and development of the fisheries sector.

1 Introduction
In West Bengal, fishers belong to lower strata of the society. Since generations, they have been directly involved in fishing but through the initiatives of the Department of Fisheries, Govt. of West Bengal, they could ameliorate their socio-economic status. The fishers can be broadly categorised as fishers by birth and fishers by profession. The average growth rate of inland fish production in India is computed to be 4.29 percent against the growth rate of around 5 percent in the state (Anon, 2000). In West Bengal, growth rate of the marine sector is less than inland sector. The coastal length of West Bengal is 950 km and area is 88.70 square km (Environmental Statistics, 2000 Central Statistical Organization, Ministry of Statistics and Programme Implementation, Govt of India). The people of the State are basically fishmongers – 90 percent of the population wishes for fish as their staple food. They prefer freshwater and brackish water fish than marine fish. According to an estimate, demand for Indian Major Carps (Catla catla, Labeo rohita, Cirrhinus mrigala) was 0.65 million tons wherein the demand for marine fish was 0.18 million tons. Hilsa (Tenulosa ilisha) and ravas (Polydactylus sextarius) fish is very popular in the Statebut they are very scarce. The State Government has declared the fish Hilsa as the ‘State Fish’ vide G O. No. 659-fish /C-VI/4M-2/2007 dated 27.03.2007 (Anon, 2007). During the study, researchers observed aquaculture as employment oriented and economically lucrative which brought more people into this sector. Net income from per unit area of inland water-body per annum was computed to be INR 585. Nearly 50 percent of the marine fisher folks were educated. The department of fisheries had also constructed a cluster of fisherman villages with facilities of safe drinking water, sanitation, roads and community hall surrounded by tanks. A code of conduct for responsible fishery was in vogue at every stage of aquaculture being practiced in the State. Although, it needs to be reviewed further.

GIS is a system that is used to store, retrieve, manipulate and analyse geographically referenced data or geospatial data, in order to support planning and management of land use and other natural resources (Burrough, 1986). Geospatial mapping in fisheries is location based study and is a part of intelligent GIS. In developing countries, it is being increasingly used as decision support system for management of fisheries and aquaculture (FAO, 1987). The study of fishery resources in the West Bengal State was based on the secondary data of the State.

2 Materials and Methods
Secondary data had been collected from Fishery Handbook 2007, West Bengal (FAO, 1995). All the data were brought in tabular form through Microsoft Excel by allotting ID number to each district for analysis and preparation of different thematic maps of fisheries profile of the State. ArcGIS software 9.3.1 (latest version) was used for this purpose. The raster map of district level of State was scanned and saved in JPG format and registered with proper projection. After geo-referencing, the raster map was digitised at district level. After digitisation, the map of the State was integrated through different Excel sheet of fishery data with proper ID. After integrating the data and table with digitised map in ArcGIS software, the data were analysed and four thematic maps were prepared which were containing many components of fisheries (Gujrati, 2003; Singh et al, 2006).

3 Results and Discussion

This thematic map contained two layers (Fig. 1).


Figure 1 Fisher population and their occupation (2007)
3.1 Fisherman population
According to the first layer, in North 24-Paragana district (first group), there were maximum number of fish folk population (482,252) followed by 4 coastal districts (second group) population ranging between 194436 and 290374. These districts were Birbhum (200747), Murshidabad (222050), Nadia (256,000) and South 24-Pargana (254484). In third group, there were five districts with fishers’ population in the range of 984978 to 194436. These districts were Bankura (114,302), Burdwan (140,000), Midnapur (112,203), Coochbehar (136,309) and Howrah (99289). The group consisting of least number of fishers’ population (2559 to 98498) was represented by seven districts of the state. They were Darjeeling (2559), Jalpaiguai (81,030), Uttar Dinajpur (70,100), Dakshin Dinajpur (34712), Hooghly (78875), Malda (35829) and Hoogly (56157).

3.2 Level of involvement
The second layer of the map was about fisherman occupation. In this layer, more than 50,000 fishermen population had been found in the five districts of Birbhum, Howrah, North 24-Pargana, South 24-Pargana and Bankura who were fully involved in fisheries activities only. More than 50,000 fishermen had been found to be involved in fisheries activity partially in the districts of Birbhumi (68,115), Burdwan (98,000), North 24-Pargana (82678) and Bankura (57,000). As occasional fishermen, there are more than 25,000 population in Murshidabad (149069), Nadia (34,780), Birbhum (51918), North 24-Pargana (25864) and South 24-Pargana (37,317). More than 100 thousand fishermen population in inland fisheries had been found in 8 districts of West Bengal. These were Coochbehar (136309), Murshidabad (200747), Burdwan (140,000), North 24-Pargana (254484), South 24-Pargana (264585) and Bankura (114,308).

3.3 Fisherman Co-operative Society
In the east of West–Bengal, the districts such as South 24-Pargana, North 24-Paragana, Malda, Howrah, Hoogly, Midnapur and Coochbehar had maximum number of co-operative society belonging to fishermen. Due to fisherman co-operative society, these districts produce more fish, especially through aquaculture. In these regions, marketing facilities and other conditions are also quite good for fish farmers. The districts which are situated in western part of the state are not that developed with respect to marketing facilities and cold storage as compared to eastern districts of West Bengal which are adversely affecting fish production (Eta, 1996). In some parts of the state, fish farmers do not apply proper feed to fish ponds and village ponds are not well maintained. In certain parts of the state, non-availability of good quality fish seeds in the vicinity is also a problem besides the fact the state is well known for fish seed production. It has been reported that fish farmers do not stock proper size of fish seed and stocking ratio of fish seed such as surface feeder, column feeder and bottom feeder, as recommended under composite fish culture practice, is also not maintained. At present, the primary fishermen co-operative societies posses around 18841.61 hectare water bodies. These water bodies are very productive but the productions are very less i.e. around 600 to 1200 kg/ha/year. With adoption of modern fish culture technology, the fish production can be increased easily up to 6000 kg/ha/year. Some times, adverse climatic conditions are also responsible for poor fish production (Everson et al, 1993).

3.4 Fish Production
Figure 2 contains three layers namely:

  1. Variations in fish production in percentage
  2. Total inland fish production
  3. Total marine fish production

According to fish production layer, there are certain districts which showed decreasing trend. According to these layers, five districts showed decreasing trend in fish production between 2005 and 2007. The decreasing trend in fish production varied in the range of -47.59 to – 29.55 % during 2005 to 2007. In the next group, Malda district showed decline up to -22.36% followed by coastal districts – Hooghly (- 9%) and Barasat (-1%). In remaining 12 districts, fish production increased between 2005 and 2007, which includes Birbhumi (42.61%) and Howrah (41.74%).

Layer three shown through Pie diagram tells that only two districts namely Midnapur and South 24-Pargana produce marine fish.


Figure 2 West Bangal fish production
3.5 West Bengal water resources
Figure 3 contains four layers.

  1. District-wise water logged area
  2. District-wise freshwater area (canals, rivers, bheels etc.)
  3. District-wise brackishwater area
  4. District-wise derelict water bodies

3.5.1 District-wise waterlogged area
This layer in the map contains five group of water logged area. Maximum water logged area has been found in three districts namely North 24-Pargana (140,000 ha), Midnapur (96,000 ha) and Murshidabad (62,000ha). Second group ranges (48,000 to 62,000 ha) containing three districts namely Hooghly (50,000 ha), Nadia (52,900 ha) and Burdwan (48,000 ha). Third group which also contains three districts in the range of 20,000-48,000 ha, are the districts of South 24-Pargana (35,000 ha), Howrah (35,000 ha) and Malda (20,000 ha). In the last group of this layer, there are those districts which occupy less than 9000 ha waterlogged area. It contains 3 districts namely Uttar Dinajpur (4000 ha), Bankura (2000 ha) and lastly Purulia (100 ha). West Bengal state is blessed with a vast waterlogged area. Every district has got waterlogged area. These waterlogged areas are the real potential of the state for pisciculture (Ramchandran et al, 1998).


Figure 3 West Bangal Water Resources (ha)
3.5.2 District-wise freshwater area
Layer of this map shows freshwater areas available the state in the form of rivers, canals and bheels etc. These freshwater areas are very important for fish production. There is only one district namely Murshidabad which consists of more than 20,000 ha area under river. Rest of the districts has less than 20,000 ha area under river.

With respect to bheels, there are only two districts namely North 24-Pargana (8861.19 ha) and South 24-Pargana (5749.47 ha) which have more than 5000 ha of bheels under their control. More than 3000 ha bheels are contained in 7 districts. Out of these seven districts, namely Malda (4551.55 ha), Nadia (4271.61 ha) and Hooghly (3884.76 ha) have large area of bheels under their administrative control for the development of the fisheries.

3.5.3 Brackishwater area
Third layer contains brackishwater area. In the state of West Bengal, only three districts contain brackishwater area. These are North 24 Pargana (140,000 ha), South 24 Pargana (335,000 ha) and Midnapur (5630 ha).

3.5.4 Derelict water bodies
Fourth layer is the impounded freshwater area. This layer contains culturable semi-derelict and derelict water bodies. Area of more than 15000 ha brackishwater is found in five districts of the state namely Murdishabad (16162 ha), Midnapur (21887 ha), Bankura (20618.79 ha) and Birbhum (15660 ha). The district Purulia occupies maximum area under semi-derelict water bodies. Most of these waterbodies are good for aquaculture. The districts of Darjeeling and Paschim Dinajpur have negligible semi-derelict water bodies.

3.6 Shrimp production
Based on the data of Inland shrimp production from 1996-2007 (Fig. 5&6), the growth rate of shrimp production was calculated. The average growth rate of the inland shrimp production was calculated using average growth formula and was found to be (10.67%). Marine shrimp production showed better growth rate during 1996-2007 in comparison to inland shrimp production. Average growth rate was found to be 12.35%. Exports of the shrimp production increased in terms of quantity i.e. 4.23% and in terms of value as well (4.65%). Table:1 shows both inland and marine shrimp production over the years.

3.7 Fish Consumption Pattern
According to Figure (4), the demand of fish in West Bengal is more in comparison to supply indication high level of fish consumption by the people of the state. To fulfill the gap between demand and supply, the freshwater fish is imported from the states like Andhra Pradesh, Bihar and Bangladesh.


Figure 4: Demand and Supply of Fish in West Bengal

Table 1: Growth rate of Shell Fish in West Bengal during 1996-2007

Figure 5: Inland shrimp production (1996-2007)

Figure 6: Marine shrimps Production in West Bengal (1996-2007)
4.0 Conclusion
The pattern of fisheries profile of West Bengal is highly variable in fish production in east and west part of West Bengal. Even fisherman population is more in eastern districts of West Bengal in comparison to western districts of the state. The supply of fish is less in comparison to consumption. Map 3 shows there is sufficient inland water resources which can fulfill the demand of fish in West Bengal if proper resource based technology and support system from the government is extended to the fish farmers for fisheries development. Purulia and its surroundings districts where good potential for inland water resources are existing, can be exploited for more fish production, while the fact remains that inland production from Purulia district has decreased up to -47% due to lack of trained manpower, infrastructures and marketing facilities. Skilled man powers are urgently required to increase fish production from untapped aquatic resources. Based on demand –supply gap, it is needed to provide modern fish technology for fish production and financial assistance in some form to poor fisherman and co-operative society so that they can take up fish farming at large scale. With increase in fish production, the import of fishes from Andhra Pradesh, Bihar and Bangladesh will be wiped out.

Acknowledgment
The authors are grateful to the Director, Central Institute of Fisheries Education, Mumbai, India for providing necessary facilities and encouragement to carry out of this work.

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