Name of Fishery Babylonia Fishery (Gear –Trawl)
Target Species Babylonia sp.
Location India-South west coast (Kollam)
Fishing Area FAO 51 (Kollam)
Fishery History Around last two decades two species of whelks viz., Babylonia spirata and Babylonia zeylanica of the family Buccinidae began to be fished and exported under the trade name ‘Baigai’ to China, Singapore, Thailand and Europe (MPEDA, 2005). The annual catch of Babylonia spp. In Kollam Harbour increased from 188.9 t in 1993 (Appukuttan and Philip, 1994) to 586.5 t in 2002 (Anjana et al. 2012) and to 1508 t in 2016 (CMFRI, 2017-unpublished).During 1996, there was decline in the shrimp landings and increase in export demand for whelk resulted in targeted trawling for whelk started as a substitute for shrimp trawling from the year 1996 onwards, in Quilon (Kerala), India (Sabu et al. 2005)
Stock Biology Biological Information such as dominant size group in fishery, Lmax, growth, life span, Length at first maturity, sex ratio, spawning season, etc. are available. Other information such as growth and mortality parameters, standing and spawning stock biomass, exploitation ratio, CPUE, landings, sampling details are also available for a limited period.
Data on Target
Species population Landing data for Babylonia sp. are available from 2001 onwards. Fisheries data are collected through CMFRI designed Multi-Stage Random Sampling method. Peak fishing season for both species was April -June. Most of the B. spirata fishery (88%) was composed of 30-46 mm shell length (SL) group. B. zeylanica of 46 to 64 mm length dominated the fishery (87.2%). Smaller size group in B. spirata (< 30mm) and B. zeylanica (<40 mm) forms up to 10%. The observed Lmax of B. spirata and B. zeylanica were 58.9 and 68 mm respectively. Both the species appear to grow at fast rate and attains maximum size within 3 years. The life span of B. spirata was calculated as 2.8 years and of B. zeylanica as 2.6 years. B. spirata spawns throughout the year with two peak-spawning periods viz, September to December and February to March. Shell height at first maturity was estimated as 32 mm and 36.5 mm for male and female B. spirata respectively. The sex ratio studies showed that females dominated the population of whelk. The mean CPUE for whelk ranged from 7 – 9 kg/h during 2001-2003 (Anjana et al. 2012). The whelk trawl is efficient in obtaining an average CPUE of 400 kg per day per boat (CMFRI, 2004).
Population parameters and biomass estimated from the fishery of B. spirata and B. zeylanica during 2001 -2003 are given in Table below. The exploitation rates of B. spirata and B. zeylanica have reached the optimum level and the population is under fishing pressure. However, the fishery is able to sustain because both the whelks are having a higher growth rate compared to other gastropod species such as the sacred chank (Xancus pyrum) (Devaraj and Ravichandran, 1988; Lipton and Selvakku, 2001)
|B. spirata||B. zeylanica|
|L∞ ( mm)||68.7||76|
|Spawning stock biomass (t)||92.9||267.7|
|Standing stock biomass (t)||216.2||404.1|
|Recruitment numbers||84,565||92, 782|
Fishing Activities Babylonia sp was caught in all the months except during July when there is a regulatory ban on trawling. Whelk is obtained as bycatch from shrimp trawling in all seasons except April-June when it is targeted (Sabu et al. 2005). April –June is the peak season for whelk fishery. During the peak season, modified shrimp traw net i.e whelk trawl is operated. Though the fishery of Babylonia sp. started as a trawl bycatch (Appukuttan and Philip, 1994), it gradually developed as a resource worth fishing exclusively with suitable modifications made in the trawl gear (Sabu et al., 2005). During the peak whelk fishing season (April-June), modified trawl nets (> 40 boats) with additional weight in the foot rope and 40 mm cod-end mesh size are used. The fishing starts in the early morning for B. spirata, while B. zeylanica is fished during night hours. Hauling is done 5 to 6 times a day depending on the catch. Each haul takes about 15 to 30 min.
Probability of capture, L25, L50 and L75 in the trawl net during 2001- 2003 estimated were 33.06, 35.2 and 37.09 mm respectively for B. spirata and corresponding values 39.74, 41.7 and 43.52 mm for B. zeylanica respectively (Anjana et al. 2012). The Lopt estimated for B. spirata and B. zeylanica was 40 mm and 44 mm respectively. Typical whelk trawl is a two seam trawl with a head rope length of 24 m and longitudinal length of over 27.4 m. Whelk trawling is conducted by medium size trawlers of 13.64 to 16.67 m LOA and larger trawlers of > 16.67 to 18.27 m LOA (Sabu et al. 2005)
Ecosystem Impacts The sedentary lifestyle of Babylon sp. makes them vulnerable to overfishing and may require a novel management approach in future. Any fishing gear that is towed over the seabed will disturb the sediment and the resident community to some degree. The intensity of this disturbance is very much depended on the details of the gear and the sediment type (Hall, 2000). Physical disturbance leads to community changes in the benthos (Ball et al., 2000). The whelk trawl is a heavily rigged gear with 45-55 kg of lead in the footrope. Its operation may cause negative ecological impact on the benthic community, of both direct and indirect nature, due to ploughing effects on the sea bottom. Hence, the operation of this gear in the traditional fishing grounds may need to be restricted. There is no ETP species encountered during the fishery.
Sustainability During 2001-2003, the Z and F values were higher for B. spirata than that of B. zeylanica. The present rate of exploitation of B. spirata was the same as the optimum exploitation rate whereas for B. zeylanica the present exploitation rate was a little less than the optimum. The faster growth rate, fast population turn-over ratio, continuous breeding behaviour, short life span, three months targeted fishing and partial harvest for the rest of the year of the species explain the sustainable fishery of the whelks is under a higher exploitation rate. Moreover, the undersized whelks are not exploited, since the presence of younger ones was negligible in the commercial fishery. Hence, the present state of fishing is not leading to a stock depletion of whelk population in south-eastern Arabian Sea (Anjana, et al. 2012). Maintaining adequate spawning stock and preventing recruitment overfishing should be the chief goals of fisheries management to ensure the future productivity of the stock and therefore no further increase in effort is recommended. Babylonia spp contributed 55.5% of the total gastropod by catch in shrimp trawlers off Quilon in 1993-94 (Sabu et al. 2005). Other by catch includes gastropods, flat fishes, dead shells (Sabu et al.2005)
Agencies CMFRI and State Fisheries Department play an important role in restricting landing of undersized whelk through mesh size regulation by stage fisheries polices. Scientific advices are provided by CMFRI. Apart from these, there are no species specific management agencies to monitor this resource.
Management KMFR Act
Compliance Yes fishers comply with management regime if it is applied through their concurrence and knowledge.
Management Community is not involved in the management of the fishery.
Marketing The whelk resources have high demand in the international market (CMFRI, 2004). In India, they are utilized as food, lime shell and for ornamental purposes. Whelk meat is being exported to Southeast Asian countries, Australia, France and China in frozen condition since 1997 and export to live whelk to Thailand and Hong Kong from 2001 onwards (Sabu et al. 2005). During 2001-02, India exported 16 t of live whelks valued at Rs. 0.88 million. Operculum of whelks is exported under the trade name ‘fish nail’ for pharmaceutical purposes (Selvarani, 2001; MPEDA, 2004).
Interest in Certification Fishery interest in certification will be decided based on stake holder meeting shortly
Stake holders Key stakeholders are fishers, buyers and processors/exporters
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