Mangrove Red Snapper (𝙇𝙪𝙩𝙟𝙖𝙣𝙪𝙨 𝙖𝙧𝙜𝙚𝙣𝙩𝙞𝙢𝙖𝙘𝙪𝙡𝙖𝙩𝙪𝙨) Culture Systems and Demand for Stocking Fish in Southern Coastal Thailand

Abstract

Background and Objectives: Mangrove red snapper (Lutjanus argentimaculatus) is a high-value marine fish with potential for coastal aquaculture, yet evidence linking actual culture systems to farmers’ requirements for stocking-fish size, quality, quantity, and delivery timing remains limited. This study examined culture systems, estimated farm-level demand for stocking fish, and analyzed the factors and constraints affecting adoption decisions across four southern coastal provinces of Thailand. National statistics do not report aquaculture production of this species separately, while marine-capture data for the broad red-snapper category do not distinguish L. argentimaculatus. Such statistics therefore cannot directly represent farm demand. The findings were intended to support stocking-fish production and distribution aligned with actual farm calendars, not to estimate aggregate provincial, regional, or national demand.

Methodology: This descriptive cross-sectional study used a convergent mixed-methods design. Data were collected from September 2024 to May 2025 from 80 purposively selected informants: 40 mangrove red snapper farmers in Ranong and Phang Nga and 40 coastal aquaculture farmers not currently culturing the species in Ranong, Phang Nga, Chumphon, and Prachuap Khiri Khan. Two structured interview schedules and a field-observation form were used. Quantitative data were analyzed using frequencies, and percentages; qualitative data were analyzed by content analysis and integrated with the quantitative findings. Sites and informants were purposively selected as information-rich cases with direct experience relevant to the research questions. The instruments covered farm and cage characteristics, fish sources and prices, transport, stocking density, grading, grow-out duration, feed, cycles, preferred sizes and quantities, decision factors, and constraints. Three experts assessed item–objective congruence, which ranged from 0.67 to 1.00. The researchers conducted face-to-face interviews, observed farms, and prepared field notes. Interview and observation evidence was compared, and interpretations were checked against original records. Requirements were calculated for a simulated 10-cage farm operating one or two annual cycles, separately for each size class and without losses or replacement fish.

Main Results: All 40 mangrove red snapper farms used floating cages near communities at canal mouths, river mouths, or coastal sites and sourced 7.50–20.00 cm stocking fish from the wild, local fishers, collectors, and fisheries agencies. Among the 80 informants, 10.01–15.00 cm fish were most preferred (n = 37, 46.25%), followed by 7.50–10.00 cm (n = 30, 37.50%) and 15.01–20.00 cm fish (n = 13, 16.25%). Under a simulated 10-cage farm scenario with one or two production cycles annually, estimated demand was 540–1,440 fish per year. Purchasing decisions emphasized vigor, size uniformity, disease tolerance, price, and availability, while major constraints were irregular supply, size mismatch, and transport. Two cage dimensions were recorded: 3 × 3 × 2.5 m and 2.5 × 2.5 × 2 m. Prices for the three successive size classes were approximately THB 15–18, 20–30, and 30–40 per fish. Transport covered no more than 100 km and took 1–2 hours in aerated tanks. Reported stocking densities were 4.0, 3.5, and 3.0 fish/m3, and grow-out periods to at least 600 g were approximately 8–9, 7–8, and 6–7 months. Fresh fish was the principal feed. Stocking was concentrated in February–March and June–July. In the one-cycle scenario, requirements for the three sizes were 720, 630, and 540 fish; in the two-cycle scenario, they were 1,440, 1,260, and 1,080 fish, calculated separately. Each respondent selected one main factor: the first two categories together accounted for 52.50%, and the first four for 81.25%. Non-adopters’ considerations formed four themes—quality, price and service, readiness for culture, and trust and networks—while anticipated constraints were uneven size, transport injury, latent disease, and price fluctuations.

Conclusions: Stocking-fish supply systems should integrate production, size grading, health screening, transport, and delivery with farm production calendars through advance ordering and post-delivery monitoring. Because demand was derived from a farm-level simulation, the findings apply only to the study sites or farms with comparable conditions and should not be interpreted as provincial, regional, or national estimates. Advance orders should specify source, size, quantity, delivery date, and destination, supported by protocols for grading, health screening, acclimation, transport, and post-delivery monitoring. Although 10.01–15.00 cm was most frequently preferred, planning should jointly consider quality, availability, price, and service. Broader application requires inventories of active farms and cages, cage-system trials of survival, cost, and return, and longitudinal monitoring of water quality, fish health, and transport outcomes.