मानवजन्य क्रियाकलाप और समुद्री मात्स्यिकी

मानवजन्य क्रियाकलाप और समुद्री मात्स्यिक

आरोग्याची देखरेख आणि रोगांचे व्यवस्थापन

The culture of marine finfish in cages was successfully initiated in Japan in 1950s and in South East Asia during 1970s. In the initial years of cage culture, fish seed for culture was collected from the wild. Recent developments in hatchery technology and seed production of commercially important marine finfish and shellfish have ensured the continuous supply of seed for mariculture practices. The disease control and health management are important issues for sustainable aquaculture. The disease occurrence causes major economic loss to aquaculture farmers. Production costs often increase due to disease outbreaks and treatment procedures followed to overcome death of fishes during culture. In natural aquatic environments, disease problems are unnoticed as diseased/weak/stressed fishes are easily removed by predators and very few occurrences of disease outbreaks are reported. Moreover in natural environment fish are not crowded as in captive culture conditions, which ultimately causes stress in fishes frequently

आँध्रप्रदेश की परुषकवचि (क्रस्टेशियाई) मात्स्यिकी संपदाएं

आँध्रप्रदेश की परुषकवचि (क्रस्टेशियाई) मात्स्यिकी संपदाए

चेन्नई और नीण्डकरा बन्दरगाह में अवतरित ब्राकिचूरन कर्कटों की जैवविविधता – एक झलक

कृपया पूरा लेखा पढ

Selective Breeding and Development of Disease Resistant Broodstock of Black Tiger Shrimp Penaeus monodon Fabricius, 1798

The Indian tiger shrimp Penaeus monodon is the principal species being cultured. Of late hatchery sector is being dependent on wild gravid females due to non response of broodstock to eyestalk ablation. High cost of gravid females compelling the grow-out sector to stock pathogen carrier seeds. Hence domestication of tiger shrimp is essential to produce Specific Pathogen Free (SPF) broodstock / Disease Resistant (DR) broodstock. Merits and demerits of SPF versus DR broodstock are presented. Development of SPF broodstock involves stringent management of environment to arrest the entry of pathogens and more than one economic trait can be selected. Whereas in development of DR broodstockanimals are challenged with the pathogen and a selection of other economic traits are less possible. Resistance in shrimp exists at the species level as well as individual level. Experiment on domestication of P. monodon in which programme was advanced up to F3 generation has revealed the existence of resistance for WSSV at the individual level. Selective breeding programme for development of D R broodstock involves development of disease free base population, forming them into families, production of F1 generation family wise through inbreeding, challenging each family with WSSV at 3-5 g size and rearing survived individuals up to 100 g size, production of F2 generation by random inter crossing between families, advancing the programme up to F5 generation. Development of DR broodstock is imperative to ensure sustainable shrimp productio

Health monitoring and disease management

The culture of marine finfish in cages was successfully initiated in Japan in 1950s and in South East Asia during 1970s. In the initial years of cage culture, fish seed for culture was collected from the wild. Recent developments in hatchery technology and seed production of commercially important marine finfish and shellfish have ensured the continuous supply of seed for mariculture practices. The disease control and health management are important issues for sustainable aquaculture. The disease occurrence causes major economic loss to aquaculture farmers. Production costs often increase due to disease outbreaks and treatment procedures followed to overcome death of fishes during culture. In natural aquatic environments, disease problems are unnoticed as diseased/weak/stressed fishes are easily removed by predators and very few occurrences of disease outbreaks are reported. Moreover in natural environment fish are not crowded as in captive culture conditions, which ultimately causes stress in fishes frequently

Exploitation of penaeid shrimp resources by small mechanised trawlers off Visakhapatnam, Andhra Pradesh

Small trawlers (9-11 m OAL) fit for short-term cruises (2-7 days) exploit penaeid shrimps up to a depth of 70 m in the Bay of Bengal off Visakhapatnam both in the northern and southern directions. During the period 2001 to 2010, average annual fishing effort was 5,97,412 h. Penaeid shrimp catch varied from 703 t to 4,323 t with average catch per hour (cph) being 3.54 kg. The contribution of penaeid shrimps to total fish landings ranged from 6.7 to 18.32%, both fishing effort and landings of the resource showing increasing trend. Penaeid shrimp landing was supported by 24 species, dominated by Metapenaeus monoceros followed by Metapenaeus dobsoni. Mean annual species composition and cph for each species were estimated for two spells i.e., 2001 to 2005 and 2006 to 2010. Catch per hour for five species declined whereas it increased for the rest 19 species. The cph for penaeid shrimps increased by 103% from spell 1 to spell 2. Expected catch for each year was estimated by Schaefer production model (CEDA; r2=0.72) which showed that the resource was under exploitated during 2001-2005 and overexploited during 2006-2010, which indicate the necessity for restricting fishing effort at present level

Trends in penaeid shrimp landings by sona boats at Visakhapatnam Fishing Harbour, Andhra Pradesh

Sona boats operate mostly in the northern part of the Bay of Bengal up to sand heads. The boats (13-15 m OAL) worthy to conduct voyage fishing for 10-20 days exploit resources upto a depth of 100 m. The present study analysed the trends in penaeid shrimp landings by sona boats at Visakhapatnam Fishing Harbour, for the period from 2001 to 2010. During the period, annual fishing effort ranged from 4,77,710 to 16,31,507 h with an average of 10,15, 230 h. Annual penaeid shrimp catch varied from 1,409 to 7,496 t, average being 4,892 t. Average catch per hour (CPH) was estimated at 4.81 kg. Annual penaeid shrimp contribution from the sona boats to the total fish landings was 10.2 to 22% (average 15.9). Both fishing effort and penaeid shrimp catch showed increasing trend during the period. Penaeid shrimp fishery was supported by 14 genera/species dominated by Metapenaeus monoceros followed by M. dobsoni. Mean annual species composition and CPH for each species were computed for two span, first being 2001-2005 and the second during 2006-2010. The CPH for the penaeid shrimps increased by 1.5% from span-1 to span-2. CPH for smaller shrimp species declined whereas increased for commercial species. Expected catch for each year estimated by Schaefer production model (CEDA; r2=0.72) showed underexploitation during 2001 and 2004; optimum state of exploitation for four years during 2005, 2006, 2007 and 2009 and overexploitation for four years during 2002, 2003, 2008 and 2010. In terms of total fish landings, 2001 and 2002 showed underexploitation, optimum state during six years i.e., 2003, 2006, 2007, 2008, 2009 and 2010; while overexploitation during 2004 and 2005. Considering the exploitation rate of both penaeid shrimps and total fish, by sona boats, the study suggests restriction of fishing effort at the 2009-2010 level to ensure sustainability of the resources

Effect of Testosterone Hormone on Performance of Male Broodstock of Black Tiger Shrimp Penaeus monodon Fabricius, 1798

In domestication and development of captive broodstock of tiger shrimp Penaeus monodon mating failures due to poor performance of male brood stock. To overcome this drawback the effect of the testosterone hormone on the performance of male broodstock was evaluated by injecting the hormone at the rate of 5 µg/g. body weight at

Radiating dipoles in photonic crystals

The radiation dynamics of a dipole antenna embedded in a Photonic Crystal are modeled by an initially excited harmonic oscillator coupled to a non--Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the Photonic Crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.Comment: Phys. Rev. E, accepte