Studies on the use of alginates in frozen fishery products

Results of preliminary studies on the use of sodium alginate as a protective coating for fishery products showed that several varieties of fishes and shell fish had better keeping qualities when coated with sodium alginate.

Chemical composition of Bombay ducks (Harpodon nehereus) and changes occurring in the nutritive value of dried Bombay ducks on storage

Fresh Bombay ducks and Bombay ducks dried (a) without any pre-treatment or (b) after brining with NaCl solutions of 15% and 7.5% concentrations for 18 hours were analyzed for moisture, ash, minerals, vitamins, fat, free fatty acids, peroxide value, thiobarbituric acid value, total protein, total amino nitrogen, soluble proteins and trimethylamine contents. All the dried samples were stored in (a) tightly closed tin containers or (b) polythene bags and analyzed for the above mentioned constituents every 1½ months. It was observed that brining did not exercise any marked influence on keeping properties. Organoleptic observations showed that fish stored in tin containers kept better and longer than those stored in polythene bags.

Population dynamics of the ribbon fish, Lepturacanthus savala (Cuvier 1829) from the north-eastern part of the Bay of Bengal

Population parameters of Lepturacanthus savala from the trawl catches in the north-eastern part of the Bay of Bengal, Bangladesh were investigated based on length frequency data, using complete ELEFAN computer program. The asymptotic length (Lα) and growth constant (K) were estimated to be 106.50 cm (total length) and 0.80/year respectively. Based on these growth parameters, the total mortality (Z) was estimated to be 1.89. The estimated values for natural mortality (M) and fishing mortality (F) were 1.08 and 0.81 respectively. The estimated value for the exploitation rate (E) using the length converted catch curve was 0.43. The recruitment pattern showed two peaks per year. The estimated sizes of L. savala at 25, 50 and 75% probabilities of capture were 57.49, 60.39 and 63.28 cm respectively. The estimated length weight relationship for combined sex was W=0.00093 TL(super)2.97

Belly depth studies for shrimp trawls - Part II

The paper details further experiments conducted for a reduction in the depth of belly of a 13.69 m (45') four seam shrimp trawl net. The investigations have given conclusive evidence that the optimum depth of belly for this particular trawl design should be 70 meshes.

Factor intensity and economic returns of alternate shrimp crop and shrimp-salt farming in the coastal areas of Bangladesh

The paper examines the factor intensity and economic returns of alternate shrimp-crop and shrimp-salt farming in the coastal areas of Bangladesh. Data were collected from 30 shrimp-crop and 30 shrimp-salt farmers, 30 shrimp farmers and 30 rice farmers from three selected coastal districts of Bangladesh. Cobb-Douglas production function model was used to determine the effect of various factors on alternate shrimp-crop farming. The chosen variables were stocking of juveniles, paddy seed, labour, fertilizers, feed and farm size of respective type of farming. The results indicated that the production function exhibited increasing remrns to scale for alternate shrimp-rice, alternate shrimp-salt and year round shrimp farming while it indicated decreasing returns for year round rice farming. Economic analysis of same system of farming indicated that higher amount of input use produced higher level of yield, gross return and net return for each type of production system.

Morphometric characteristics and meristic traits of Tilapia zillii from three major dams of a southwestern state, Nigeria

Tilapia zillii was examined in three major dams in Ekiti State, Nigeria (Ureje dam, Ado, Egbe dam and Ero dam) for their morphometric characteristics and meristic traits. The results showed that the average body weight of the fish sampled were 145.86±50.06g in Ado, 30.19±9.35g in Egbe and 40.58±52.30g in Ero dam. Average total lengths were 21.29±3.20cm, 12.32±1.74cm and 11.24±1.56cm for Ado, Egbe and Ero dam respectively. The relationship between average weight and length of T. zillii showed that Y=15.202X-179.33 (R2=0.7181), Y=4.40049±-24.075 (R2=0.6708) and Y=2.6676X10.596 (R2=0.0063) for Ado, Egbe and Ero dam respectively. The results on headlength, total length, body weight and standard length and pre-pelvic distance are significantly different at 95% among the T.zillii of the three dams. There was no significant difference in the meristic traits of the T. zillii of the three dams. The population size of T.zillii in the three dams was just too small compared to other species of fish hence the need to assess the stock of fish in these dams critically for the encouragement of proper fishing activities in these dams.

Adoption, productivity and profitability of rice-fish and fingerling culture in three selected districts of Bangladesh

The study aimed to investigate the productivity and profitability of rice-fish farming. It also determined the factors affecting rice-fish and fingerling production in Bangladesh. Among the total respondents about 55% were involved in rice-fish farming, 37% in pond fish culture and rest 9% in fish nursery. Integrated rice-fish farming contributed about 83% of the annual farm income in Comilla while it was about 20% in both Kishoregonj and Chandpur districts. Among the different farming systems integrated rice-fish culture and rearing fingerlings in the nursery pond were more profitable at the farm level. Farmers earned a net return of Tk. 49,714/ha from integrated fish culture with boro rice while the net return of boro rice-alone was only Tk. 11,179/ha. This indicated that farmer could earn 218% higher net return from integrated rice-fish farming than that of boro rice only farming. Moreover, integrated rice-fish culture also reduced pesticides cost to about 77% and weeding cost to about 51% in boro season. Fingerling nursing earned highest net returns among the three technologies.

On the comparative fishing experiments with a four-seam and a two-seam trawls on the east coast

Fishing experiments were undertaken to study the relative utility of a newly designed four seam type net on a conventional two seam net at the centre along the East Coast in both inshore and deeper zones (up to 100m.) and the results indicated that the new four seam net has given higher catch rate of 6 to 8% more with higher catch rate of fish supposed to belong to off bottom region. Further this gear found more selective in obtaining Lactarius, which is one of the good variety of fish from trawlers, in both quantity as well as in quality. In terms of horizontal spread this new net gave less on comparison with the conventional two seam net, thereby showed corresponding increase in vertical spread; but warp tension remained more or less same in both the gear. Both gear have worked equally well in majority of depth ranges experimented with optimum spread. Finally the results indicated that the new net can work well from the present trawlers along the coast.

Effects of stocking density on growth and survival of Mystus gulio in nursery ponds

A study on the effect of stocking density on growth and survival of nona tengra (Mystus gulio) was carried out in brackishwater earthen nursery ponds (2 decimal each) for a period of 42 days. Five-day old captive bred tengra post-larvae (ABL: 4.53±0.83 mm and ABW:3.33 mg) were stocked at four different densities of 200/m² (Treatment-1), 250/m² (Treatment-2), 350/m² (Treatment-3) and 450/m² (Treatment-4). Fries were fed twice a day with a mixture of fine rice bran, mustard oil cake and fishmeal at the ratio of 2:1:1. The specific growth rate (SGR) of larvae did not vary significantly (p>0.05) between T1 (5.096% mg/day) and T2 (5.08% mg/day), but it was found significantly (p<0.05) higher from T3 (4.98% mg/day) and T4 (4.91% mg/day), respectively. The final survival rates of 89.25±5.41% in T1 and 88.72±6.09% in T2 were found similar (p>0.05), but significantly higher (p<0.05) than those of, 76.20±4.77% in T3 and 70.34±5.71% in T4. The results indicate that 5-day old hatchery bred nona tengra post-larvae can be nursed in earthen pond at a stocking density of 200-250/m².

Species diversification in coastal aquaculture: production potentials of shrimp (Penaeus monodon) with mono and mixed sex tilapia

An experiment of 120 days of culture was conducted in brackishwater earthen ponds having an area of 0.2ha each. The hatchery produced shrimp (Penaeus monodon) post larvae were stocked in the 40m² fine meshed nylon net nursery enclosures were fed with commercial pellet feed. After two weeks of nursing, juveniles were allowed to spread in cultural pond by opening the fence. Fingerlings of three different strain of tilapia were stocked as shrimp and Strain-1 all male (monosex) (T1), shrimp and Strain-2 all male (T2), shrimp and Strain-3 mixed sex population (T3) @ 20.000/ha and 10.000/ha, respectively and shrimp only (monoculture) (T4) @ 20.000/ha. The shrimp and fish were fed with farm made feed consisting of a mixture of fishmeal 29%, MOC 15%, rice bran 30%, soybean meal 16%, wheat flour 9% and vitamin premix 0.1%. The average final weight of shrimp was 24.9±1.13g, 23.41±3.26g and 26.67±1.89g that stocked with tilapia in treatments T1, T2, and T3 respectively. The final average weight of shrimp in monoculture (T4) was 27.41±0.76g, apparently higher but insignificant in treatments. The survival of shrimp was 42.17%, 32.38%, 39.45% and 61.98% in treatments T1 T2, T3 and T4 respectively. The production of shrimp in concurrent culture was 193.67, 154.26 and 210.41kg/ha in T1, T2 and T3, respectively, while in monoculture (T4) was 339.77 kg/ha. The growth and survival of tilapia among the treatments was insignificant. The growth of monosex tilapia ranged 225.29 and 291.31g and survival 62.77 and 72.20% in T1 and T2, respectively, in mixed sex was 193.0g and 83.20% (T3). The production of tilapia monosex strains was 1676.69kg/ha (Strain-2 all male) and 1668.98 kg/ha (Strain-1 all male) while that of Strain-3 mixed sex population was 1622.92 kg/ha.

Abundance and composition of benthic fauna in Penaeus monodon Fabricius culture pond on the west coast of Malaysia peninsular

This paper reports a study on the benthic faunal abundance and diversity of tiger shrimp P. monodon culture ponds in Perak, west coast of Malaysia Peninsular. Sampling was carried out at three weeks interval throughout the 116 days culture period. In addition, water temperature, dissolved oxygen, salinity, transparency, pH and organic matter of soil were also measured. Results showed that the major groups of macro-benthos comprised of gastropod, foraminifera, polychaetes, bivalve and insects; whereas the meio-benthos comprised of harpacticoid copepods, ostracods, nematodes, gastropods, foraminifera, bivalve, insects, crustacean nauplii and polychaetes. In macro-benthos, the abundance of different sizes of Gastropods increased throughout the culture duration. This consisted of 37-98.20% for <1cm length, 1.80-61.50% for 1-2cm length and 1.18—1.30% for >2cm length. Other macro and meio-benthic organisms decreased linearly with the culture period. The depletion symptom indicates that the culture species may have intensively preyed upon the consumable (<0.5cm in size) benthic fauna together with detritus and artificial diet; or could have been caused by pond bottom deterioration via uneaten feed, faces and toxic gases.

Comparison the nutritional value of cultured Penaeus vanname with marine shrimps Penaeus merguiensis and Penaeus semisulcatus

The purpose for which this study was intended wasto compare nutritive value among the farmed Vannamei, sea Green Tiger and Banana shrimps native to the PersianGulf. To provide the samples of farmed shrimps at the end of the farming season (Oct. 23rd through Nov. 22nd of 2011), we chosen one farm of the Holleh Shrimp Farming, from which 100 shrimps were randomly selected. From among these 100 shrimps, 3 to 5 ones were taken to conduct an analysis upon. Further, to obtain the Banana and Green Tiger shrimps sampling was done at the fishing season (July 23rd through Aug. 22rd of 2011) at Halileh Fishing Wharf located in Bushehr Fishing Harbor and also Bandar Abbas Wharf. The samples obtained were immediately kept in the ice powder. After some biometric tasks done upon them, they were at the shortest possible time transferred to a laboratory where they went through various experiments to determine their content of raw protein, fat, ash, moisture, various fatty acids and their types, cholesterol, vitamins A and E, and such mineral elements as iron and calcium. All the experimentswere carried out three times to establish confidence in the results to be obtained. Findings of the comparison showed the content of raw protein, fat, moisture, and ash of, respectively, 23.233%, 600%, 73.077% and 2.500% for the Vannamei samples, of 22.717%, 427%, 74.133% and 1.826% for our Banana shrimps and of 17.377%, 430%, 79.866% and 1.313% for the Green Tiger samples. A total of 24 fatty acids for the Vannamei shrimps and 27 for the Banana and Green Tiger were detected. SFA of the Banana shrimps was 368.45 mg/100g (51.76%), while those of the Vannamei and Green Tiger samples were observed, respectively, 363.54 mg/100g (37.26%) and 296.06 mg/100g (49.12%).A similar measurement for MUFA content of the three types of our samples revealed 243.85mg/100g (24.9%) for the Vannamei, 203.177 mg/100g (33.76%) for the Green Tiger and 179.033 mg/100g (25.14%) for the Banana shrimps. The content of PUFA unsaturated fatty acids in the Vannamei, 131 Green Tiger and Banana samples were, respectively, 370.660 mg/100g (37.84%), 101.573 mg/100g (16.9%) and 163.733 mg/100g (23.1%). Further, the comparison found a omega-3-fatty-acids total of 151.747 mg/100g(15.51%) for the Vannamei, 57.123 mg/100g (9.54%) for the Green Tiger and 130.460 mg/100g (18.46%) for the Banana species under study.

Survey of marine turtles ecobiology in north of Persian Gulf

Sea turtles are counted as rare and extincting species. During the last century the population of sea turtles are drastically reducd and the remaining ones are considerd either threatend or endangerd because of some factors as sea pollution, economic benefits, intense fishing effort, beach man-made structures and so on. So, in recent years, more attention to conserving and surviving them is assumed. After a preliminary studies on some of the biological specifications in northern beach of Persian Gulf, three islands ; Hormoz, Hengam and Larak for the biometry of the turtles, a total number of 179, from 1999 to 2002 (4 years) are chosen. Some of the biological attributes as weight, length and their egg-laying are recorded, these items are then analyzed using SPSS software. The observed results are as follows . The lowest weight of the turtles was 35 kg, the highest 59 kg, and the average 45.24 kg. The lowest carapace length was 64 cm. the highest 86 cm and the average 76.79. the lowest number of laying eggs was 73, the highest 126, and the average 86.79. The results are discussed in three following sections: 1-A contrastive analysis of the biometric characteristics during 1999 in the three mentiond islands. 2-A contrastive analysis of the biometric characteristics in Hormoz island from 1999 to 2002. 3-A contrastive analysis of all the biometric characteristics in the three islands and other parts of the world. The results obtained from the turtles biometry in 1999 shows that the average of the turtles weight in Larak is lower than the other mentioned ones, and the heighest average is observed in Hormoz island. The turtles of Hengm have laid more eggs than the others. The results of Hengani turtles biometry during 1999-2002 indicates that the average of their weight in 2002 is more than the other three years in the same place. The least number of eggs laid during these years are 53 and the most are 126. The most number of eggs are laid in Hormoz in 2002, but the average number does not show any significant change.

Growth rates of Tilapia esculenta (Graham) and Tilapia zillii (Gervais) under cultivation in ponds at Nyegezi, Tanzania

Aquaculture in Tanzania is still on a subsistence level and most of the ponds are maintained as part time job. The ponds are too small, shallow and over crowded with stunted Tilapia spp. In the present paper the results of experiments conducted in ponds at Nyegezi with T. esculenta and T. zillii are presented. This was part of an overall project of developing techniques of fish cultures with Tilapia under the limited existing conditions at Nyegezi. In a mono - species culture experiement with Tilapia zillii in nine month's time an average size of 172.8 mm/115.0 g was attained. In another experiment with T. zillii and T. esculenta in thirteen month's time, T. zillii attained an average size of 180.2mm/106.6 g and T. esculenta 193.6 mm/118.8 g. In another experiment with intensive feeding schedule an average size of 179.3 mm/126.6 g was attained by T. zillii and 191.0 mm/125.0 g by T. esculenta in four month's time. A locally prepared supplimentary feed with local Brewery Waste and Fish Meal (10:1) was readily accepted by both species of Tilapia. T. zillii voraciously fed on Cabbage leaves, Cauliflower leaves, Chinese cabbage leaves, Cassava leaves and on the common weed Comalina sp. Though all the items mentioned above were readily accepted by T. zillii feeding with Comaltna sp. was the easiest and most convenient because of its availability. In an intensive feeding experiment with vegetable leaves/Comalina sp. and the locally prepared supplimentary feed the fishes attained table size in four months time. Cement cistens of 5 X 3 X 1½ m size could be conveniently used for breeding both species of Tilapia. T. zillii had semi adhesive eggs and they were deposited on the sides of the cement wall. The number of young ones in a brood ranged from 160 to 314 in T. esculenta and 687 to 4,356 in T. zillii.