Using length data to derive biological reference points for kiddi shrimp Parapenaeopsis stylifera (Milne Edwards, 1837) from the south-eastern Arabian Sea, India

Parapenaeopsis stylifera, a major commercial penaeid shrimp fishery resource in the Indian Ocean, has lacked adequate information on life history parameters for nearly two decades. In this study, growth and mortality parameters of P. stylifera from the southwest coast of India were estimated using length data and used to derive biological reference points for the species. The asymptotic length for females was L∞ = 131 mm; k = 1.1 y−1 and for males L∞ = 117 mm; k = 1.25 y−1. Mortality parameter estimates were Z = 4.42, M = 1.24, F = 3.18 y−1 and exploitation rate E = 0.72 for females; Z = 5.76, M = 1.39, F = 4.37 y−1 and E = 0.76 for males. Thomson and Bell yield biomass, Beverton and Holt yield per recruit, and relative yield per recruit models were applied to predict the stock status and length cohort analysis for estimating the stock size. The Beverton and Holt analysis gave Emax = 0.69 in females and 0.75 for males, which is below the Ecurrent values obtained for the sexes. The Thomson and Bell analysis indicated that if Fcurrent at which the yield is 121 460 t in females and in males 128 064 t is further increased, rise in yield will be modest. B/B0 and SB/SB0 at Fcurrent were 24% and 18% for females and 21% and 16% for males, respectively. Target reference point F0.1 and F0.5 at different levels of age at capture tc (0.5, 0.6, 0.7 and 0.8 yrs) was estimated by Beverton and Holt yield per recruit model. The outcome from these models forms integral inputs for multispecies/multigear tropical fisheries management. Parapenaeopsis stylifera is one of the inshore penaeid shrimp identified by the Marine Stewardship Council for certification from the region and, moreover, biological reference points are a prerequisite to assessment and management of tropical multispecies fisheries for ecosystem-based fisheries management

Zooplankton phototaxis in oceanic squid fishing grounds in the Arabian Sea

1528-1532<span style="font-size:9.0pt;mso-bidi-font-size: 11.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">Effects of night-illumination on zooplankton abundance were compared with day/night variations in oceanic squid fishing grounds in central Arabian Sea. Zooplankton abundance sh<span style="font-size:9.0pt; mso-bidi-font-size:11.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:="" "times="" roman";color:black;mso-ansi-language:en-gb;mso-fareast-language:="" en-us;mso-bidi-language:ml"="" lang="EN-GB">owed significant variation in relation to three different light conditions with 52% of the total abundance happening during night and 25% during night with illumination. Siphonophores, chaetognaths, copepods and decapod larvae displayed negative phototaxis. Present results indicate that the <span style="font-size:9.0pt;mso-bidi-font-size:11.0pt; font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" ml"="" lang="EN-GB">response to light stimulus observed among the zooplankton groups were mostly due to the prey-seeking or predator avoidance behavior.</span