Decrypting the life history characteristics and stock dynamics of Parapenaeopsis stylifera (Milne-Edwards, 1837) in the north-western Bay of Bengal: A confluence of approaches for better decision support

Dash, Gyanaranjan and Dash, Swatipriyanka Sen and Pradhan, Rajesh Kumar and Kumar, Rajan and Chakraborty, Rekha D and Dineshbabu, A P and Ghosh, Shubhadeep (2025) Decrypting the life history characteristics and stock dynamics of Parapenaeopsis stylifera (Milne-Edwards, 1837) in the north-western Bay of Bengal: A confluence of approaches for better decision support. Indian Journal of Fisheries, 72 (3). pp. 11-26. ISSN 0970-6011

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Abstract

The life history of Kiddi shrimp (Parapenaeopsis stylifera) was assessed using lengthbased data from the commercial trawlers operated along the Digha waters (West Bengal, India). Growth parameters were estimated as L∞= 14.26 cm, K = 1.77 yr-1, t0 = -0.001 yr-1, t max = 1.5 yr and φ = 2.56. Mortality rates were M = 3.00 yr- ¹, F = 4.11 yr- ¹, Z = 7.11 yr- ¹, with an exploitation rate (E) of 0.58. The species matures early (Lm50 ≈ 8.15 cm, 0.48 yr) and attains peak biomass (Lopt ≈ 8.0 cm, 0.47 yr). A high M/K ratio (1.7) indicates r-selected traits-fast growth, high mortality, and peak yield at high fishing mortality. Cohort biomass declines rapidly to 1% within 0.65 yr, yet the short generation time allows reproduction under current exploitation. Stock status from the Bayesian Schaefer Model using catch-based data (2007-2021) showed current biomass (B/Bmsy = 1.15) is 15% higher, whereas the effort (F/Fmsy = 0.85) is 15% lower than required level for MSY. Kobe plot also indicates a higher probability (57.9%) that the stock is in the healthy and sustainable green zone. Thompson and Bell analysis suggested fishing mortality could increase by 8%, raising yield marginally by 1.6% to 2442 t and revenue by 1.3% to ₹423 million, while maintaining safe spawning biomass (SSB/ SSB0 =30%). However, due to its short generation time and recruitment sensitivity, P. stylifera requires adaptive harvest control rules with annual or biannual assessments to ensure long-term sustainability.

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