Fishery and stock assessment of the blood clam Anadara granosa (Linnaeus) from Kakinada Bay

Landing and effort data of Anadara granosa (Linnaeus) from Kakinada Bay were collected for the years 1988 to 1991. The landings during 1988 were 802 tonnes compared to 1600 tonnes in 1991. The effort in 1988 was estimated at 32,458 man-days, which has increased by 1.7 times in 1991. However, catch rates showed a declining trend. There has been some change in the exploitation pattern. Younger size groups (<30 mm) are being exploited more, due to their higher price realization. Stock assessment attempted by Jones’ Cohort analysis and Thomson and Bell analysis showed that the current level of exploitation has already reached MSY level. There is scope to increase the yields by following 1990 pattern of exploitation. However, selective exploitation of A. granosa of > 30 mm, if continued may lead to declining yields over the years

Growth and survival of the Indian Pearl oyster (Pinctada fucata) in Kakinada Bay

Kakinada Bay which has a total spread of 146 sq.km. area has diverse moUuscan resources, especially bivalves and gastropods. Several workers have studied in detail, the molluscan resources of the Bay and their fishery characteristics. The Bay also harbuors a population of resident pearl oyster, Pinctada chemnitzii towards its eastern side near Hope Island. But Pinctada fucata is an exogenous species as far as Kakinada Bay is concerned

Prospects for developing culture of edible oyster, Crassostrea madrasensis and green mussel, Perna viridis along Kakinada coast, Andhra Pradesh

Around Kakinada in Andhra Pradesh the edible oyster, Crassostrea madrasensis beds are found at Kakinada Fisheries Harbour, Chollangi and Uppada. aquaculture is location specific, in order to test the viability of this technology under the conditions prevailing at Kakinada, experimental study on edible oyster culture was taken up at Kakinada. Ren culture method was adapted.The present work was carried out by giving good publicity at the Kakinada Fisheries Harbour and in the process, considerable awareness was generated among the fishermen resulting in good protection to the rens

Mixing in the surface waters of the western Bay of Bengal using 228Ra and 226Ra

228Ra and 226Ra have been measured in the surface waters of the western Bay of Bengal during five cruises conducted between 1988 and 1999. The ranges and mean (given in brackets) concentrations for 228Ra and 226Ra are 6.8-42.1 (17.8 ± 7.9) dpm/100 kg and 6.0-16.7 (9.2 ± 2.2) dpm/ 100 kg, respectively. (228Ra/226Ra) Activity Ratio (henceforth denoted as [228/226]) ranges from 0.8 to 3.4 with a mean of 1.9 ± 0.5. Both 228Ra and 226Ra show inverse correlation with salinity, the former much stronger. A surface 2-D diffusion-advection model is used with a new approach. A simple bivariate function, C(x,y) = C0e-Ax·e-By where C0, A and B are constants, is fitted to the whole 228Ra and 226Ra data C(x,y). Substituting C(x,y) in the two-dimensional steady-state diffusion equation of Ra, the estimated values of the constants A and B can be related to eddy diffusivities and advection velocities in the zonal (x) and meridional (y) directions. From this relationship, the horizontal eddy diffusivities in the zonal and meridional directions are inferred to be 1.3 × 107 and 2.1 × 108 cm2s-1, respectively in the absence of advection terms. Similarly, neglecting the influence of diffusion, one can estimate the advection velocities, wx and wy in the zonal and meridional directions, as 0.2 and 1.1 cm s-1, respectively. The model-fit values C(x,y) of 228Ra concentrations are in good agreement with the measured values except in regions showing exceptionally high and low values. Incorporating both the advection rates and eddy diffusivities into the equation, it is found that increasing advection velocities depending on the direction can decrease or increase the eddy diffusivities and that such changes are more effective in the meridional direction compared to zonal direction in the region of study. On the whole, 228Ra appears a good tracer to derive rates of mixing between low salinity waters in the north and their high salinity southern counterparts of the western Bay of Bengal. The eddy diffusivities, Kx and Ky (without advection) derived for the Bay of Bengal are higher by about an order of magnitude than the ones similarly obtained for the Arabian Sea. This is not unexpected due to the turbulent conditions prevailing in the Bay of Bengal for most of the year

Stabilisation of Red Phosphorus to Prevent Moisture Absorptionand Suppression of Phosphine Release

Red phosphorus (RP) is an essential ingredient to generate smoke for multi-spectralobscuration and is receiving wide attention throughout the world for military applications.However, oxidation of phosphorus occurs in moist air resulting in the formation of variousphosphorus acids and subsequently the evolution of the toxic gas, phosphine (PH3), even inthe sealed systems. Entrapped moisture leads to deterioration of the stores. The commercial-RPat ambient temperature and 95 per cent  RH conditions indicates 15 per cent  moisture absorptionand 13 per cent acidity development with the generation of more than 100 ppm of phosphinegas. Efforts were made to overcome this problem by suppressing acid formation. The technologyadopted was: (i) use of stabiliser, and (ii) doping stabiliser-coated particles with polymericsubstance. The aim to use metal oxide as stabiliser was to neutralise the phosphorus acids,which are catalysing the phosphine generation. MgO due to its basic nature seems to be fasterthan amphoteric Al2O3, in removing the acid from site of reaction, thus suppressing the phosphinerelease effectively. Though MgCO3 as stabiliser suppresses moisture absorption and aciditydevelopment, phosphine release is not controlled effectively. Study of RP coated with thesematerials independently and monitoring them at different RH conditions indicated superiorityof MgO in suppressing acidity and phosphine formation

Cephalopod fishery at Kakinada along the east coast of India: Resource characteristics and stock assessment of Loligo duvauceli

At Kakinada along the east coast of India, cephalopods were exploited by trawls. Fishery occurred round the year with peak during August-October. Peak abundance and fishery of cuttlefishes coincides with this period, whereas for squids it is during March-May. Cephalopod production continued to increase initially with fishing effort, until 1995, but declined thereafter despite increased fishing effort and expansion of fishing to deeper waters. Fishery, growth, mortality, recruitment pattern and exploitation rates of Loligo duvauceli were studied

Radiometric Screening of Red Phosphorus Smoke for its Obscuration Characteristics

Red phosphorus and potassium nitrate-based compositions exhibit favorable smoke screenformation with high obscuration characteristics at low oxidiser content. The rapid vaporisationof excess red phosphorus at higher flame temperature leads to quick aerodispersion. Theobscuration characteristics are due to formation of P2O5 and subsequent reaction with moisture/humidity in the atmosphere. Obscuration increases with increasing humidity. Extinction coefficient,the shadow cast per unit mass of the composition, is higher in visible and comparatively lowerin far infrared

A note on spat settlement and growth of the pearl oyster Pinctada chemnitzii (Philippi) in Kakinada bay

Pearl oyster Pinctada chemnitzii, belonging to the family Pteriidae has been reported from Kakinada Bay. They are found in the coarse sandy-mud bottom at 0.3 to 3.0 m depth range towards eastern side of the Bay near Hope Island, attached to dead wlndowpane oyster shells. The population biomass the species in the Bay has been estimated to be 314 tonnes. Detailed study on the biology including spat settlement of the species is lacking. In the present study the spat settlement and growth of P. chemnitzii in Kakinada Bay is dealt with

<SUP>14</SUP>C in air over the Arabian Sea

Global monitoring of radiocarbon in atmospheric CO2 began during the mid fifties to determine the time scales of exchange of radiocarbon (and CO2) between the atmosphere and other terrestrial reservoirs. The distribution of natural radiocarbon in the environment was perturbed significantly during the 1960s through injection of 14C from nuclear weapon tests. This 'bomb 14C has proved to be an excellent tracer to characterize and quantify CO2 exchange between various reservoirs. We have measured radiocarbon activity of marine air over the central and eastern Arabian sea during 1993-95. The mean A 14C values are 121 ±6, 116 ±6 and 105±5%o respectively for these three years. These values, in conjunction with those reported in the literature for troposphere for the decades of 60s through 80s, show that the 14C activity in the tropospheric air has been decreasing exponentially with an e-folding time of -16 years