62 MARCH 2023 • WORLD AQUACULTURE • WWW.WAS.ORG carp nursery growers obtain spawn from government or private eco-carp hatcheries and rear them in nursery ponds. Based on the available literature, the spawn count of 6- to 8-mm IMC varies from 500/mL (Jhingran 1986) to 600-650/mL (Thomas et al. 2003). With proper management, the survival of carp spawn to fry is 30-40 percent in nursery ponds and 50-60 percent in concrete nursery tanks (Ayyapan 2011). The average survival of carp spawn to fry in nursery ponds does not normally exceed 30 percent (Basavaraja 1994). Reasons for low survival of spawn during nursery rearing include a lack of scientific knowledge for pre- and poststocking nursery pond management and predation by birds and predatory fishes, among others. Another reason for the very low survival of carp spawn in nursery ponds is the inaccurate carp spawn measurement system used in India. West Bengal is the main state for fish seed production in India, followed by Jharkhand, Assam and Uttar Pradesh. The Naihati fish seed market in West Bengal supplies fish seed across the county, moving out by road, rail and air routes. Spawns are sold in the Kolkata fish seed markets in terms of bati or kunka (4 bati = 1 kunka). The size of a bati is not fixed, varying from market to market but typically ranges from 135-170 mL, thus causing variation in the Carps are the mainstay of freshwater aquaculture in India. Total inland fish production of the country during 2019-20 stands at 10.43 million t (Handbook on Fisheries Statistics 2020) with about 57 percent contributed by Indian major carps (IMCs). The sector has witnessed a steady growth in the total Gross Value Added, accounting for about 7.28 percent of agriculture GDP and achieving a growth rate of more than 10 percent annually on a sustainable basis over five years. Despite the fast-rising demand for fish seed, a lack of knowledge regarding quality fish seed characteristics has persisted in many regions. The production of fish seed has increased appreciably, from an estimated production of 5.6 billion fry in 19841985 (Jhingran 1986) to 52.2 billion fry in 2019-2020 (Handbook on Fisheries Statistics 2020). This was possible due to the popularization of scientific breeding and hatching techniques (i.e., induced spawning) and the large-scale adoption of composite fish culture technology by fish farmers in different states. Inadequate availability of quality seeds of major cultivable species in desired quantities at right time is considered one of the major bottlenecks for enhancing farm productivity and national production. At present, 2198 eco-carp hatcheries and 417 FRP carp hatcheries are fully operational in India (Swain et al. 2021). Most The Carp Spawn Measuring System in India: Is It on the Right Track? Avinash Rasal, Jitendra Kumar Sundaray, Khuntia Murmu, Ajit Chaudhary, Mukesh Kumar Bairwa and Kanta Das Mahapatra FIGURE 1. Carp spawn measuring units/devices used across India.
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