Observation on the production performance of Penaeus monodon with Liza parsia under different cropping system

Study was conducted in six ponds each with an area of 0.1 ha in the pond complex of Brackishwater Station, Paikgacha, Khulna from February to October '96, to find out the variation of production rate in two culture system viz., single and double crop of P. monodon with L. parsia. In treatment T1 wild fry of P. monodon (0.006g) and L. parsia (0.20g) collected from nearby river were stocked at a rate of 40,000 and 10,000/ha, respectively, for a culture period of 120 days. In treatment T2, the rate was 20,000/ha for bagda fry in 1st and 2nd crop each and 10,000 for parsia fry/ha for an extended period of 225 days. The highest survivability and growth of P. monodon and L. parsia were 57.08% (1st crop of T2) and 75.26% (T2), and 27.08g (1st crop of T2) and 47.78g (T2), respectively with a significant variations (P>0.05) with other treatment. The net profit (Tk. 93,134) and cost benefit ratio of 1:1.76 were also found higher in T2.

Comparison of two hormone preparations on the reproductive performance of air breathing catfish Clarias batrachus (Lin.)

Two hormone preparations viz. Human Chorionic Gonadotropin (HCG) and pituitary gland (PG) suspension were compared for their comparative efficacy on the breeding performance of a air breathing catfish Clarias batrachus. It was found that HCG induced fish gave better ovulation response than PG. Both fertilization and hatching of eggs were significantly (pOn all consideration, HCG was found more suitable for induced breeding of C batrachus over PG.

Effects of different dietary levels of vitamin E on the breeding performance of Heteropneustes fossilis (Bloch)

Experiments on the study of different dietary levels of vitamin E on the growth and breeding performance of Heteropneustes fossilis brood fish were carried out in two phases. The first phase consisted of studying its ovarian development and the second phase on breeding performance. Sixty female fishes were stocked in twelve experimental chambers of a raceway. The effects of four dietary vitamin E levels viz. 0 (served as control), 50, 100 and 200 mg/kg feed, on the somatic growth, ovarian development of brood fish and on their breeding performance were studied. Each treatment had three replications. It was observed that body growth in terms of length and weight was best with 0 mg vitamin E/kg feed and 200 mg vitamin E/kg of feed gave poorest result. The gonado-somatic index and fecundity, however, was highest in the fish fed with 100 mg vitamin E/kg of feed. In case of breeding performance such as ovulation rate, fertilization rate, hatching rate and survival rate, the best result was obtained with 200 mg vitamin E/kg of feed. The overall result of this experiment indicates that 200 mg vitamin E/kg of feed is the best vitamin E dose for H fossilis brood and vitamin E content has a positive impact on ovarian development.

Effect of feeding bioencapsulated Lactobacillus sp. in live Tubifex sp. on the growth performance of gold fish Carassius auratus (Linnaeus, 1758)

An attempt was made to feed bioencapsulate Lactobacillus sp. in live fish food organism Tubifex for use in the culture of gold fish Carassius auratus. The C. auratus fries when fed with bioencapsulated Lactobacillus sp. in Tubifex showed significant improvement in total wet weight gain (p<0.007) and FCR (p<0.01) compared to control. The specific growth rale and mean survival were slightly higher, although insignificantly (p>0.05) in bioencapsulated Tubifex fed group. None of the bacteriological parameters of the fish gut between the experimental and control groups differed significantly (p>0.05). Lactobacillus sp. was recorded at a level of log 5.11/g on the 90th day of experimentation. When the experimental C. auratus fries were infected with Pseudomonas fluorescents, the bioencapsulated Tubifex fed group resisted the infection. The survival was significantly higher (p<0.05) in bioencapsulated Tubifex fed group (44%) than in control (22%). The C. auratus fed with bioencapsulated Tubifex showed less (55%) signs of tail/fin rot. Likewise, a significant improvement in total wet weight gain (p<0.009), FCR (p<0.01) and SGR (p<0.04) of C. auratus brooder fed with bioencapsulated Tubifex was seen compared to control group fed with depurated Tubifex.

Effects of Gear Modifications on the Trawl Performance and Catching Efficiency of the West Coast Upper Continental Slope Groundfish Survey Trawl

Since 1984, annual bottom trawl surveys of the west coast (California–Washington) upper continental slope (WCUCS) have provided information on the abundance, distribution, and biological characteristics of groundfish resources. Slope species of the deep-water complex (DWC) are of particular importance and include Dover sole, Microstomus pacificus; sablefish, Anoplopoma fimbria; shortspine thornyhead, Sebastolobus alascanus; and longspine thornyhead, S. altivelis. In the fall of 1994, we conducted an experimental gear research cruise in lieu of our normal survey because of concerns about the performance of the survey trawl. The experiment was conducted on a soft mud bottom at depths of 460–490 m off the central Oregon coast. Treatments included different combinations of door-bridle rigging, groundgear weight, and scope length. The experimental design was a 2 ´ 2 ´ 2 factorial within a randomized complete-block. Analysis of variance was used to examine the effects of gear modifications on the engineering performance of the trawl (i.e. trawl dimensions, variation in trawl dimensions, and door attitude) and to determine if catch rates in terms of weight and number of DWC species and invertebrates were affected by the gear modifications. Trawl performance was highly variable for the historically used standard trawl configuration. Improvements were observed with the addition of either a 2-bridle door or lighter ground gear. Changes in scope length had relatively little effect on trawl performance. The interaction of door bridle and ground gear weight had the most effect on trawl performance. In spite of the standard trawl’s erratic performance, catch rates of all four DWC species and invertebrates were not significantly different than the 2-bridle/heavy combination, which did the best in terms of engineering performance. The most important factor affecting DWC catch rates was ground gear. Scope length and the type of door bridle had little effect on DWC catch rates. Subsequent revisions to survey gear and towing protocol and their impact on the continuity of the slope survey time series are discussed.

Effects of different levels of energy and protein sources on the growth performance, feeding, survival rate and the chemical body composition of juvenile Pacific white shrimp (Litopenaeus vannamei)

The present study was carried out in order to establish an economical effective diet for the pacific white shrimp in the southern part conditions of Iran. With the consideration of three dietary energy levels (E1=262, E2=312, E3=362 kcal 100 g-1 diet) and six ratios of fish meal (FM) to soybean meal (SBM) [(P1=100%FM+0%SBM, P2=80%FM+20%SBM, P3=60%FM+40%SBM, P4=40%FM+60%SBM, P5=20%FM+80%SBM, P6=0%FM+100%SBM)], 18 experimental diets (with 36% crude protein) were prepared. Completely randomized design was used to assign 54 polyethylene 300 litre round tanks provided by aeration and flow through water system and was stocked by 19 juvenile as 3 replicates to each treatment. Shrimps average weight was about 0.77 grams at the start. After 56 days culture period, maximum growth and nutritional performances were observed in the P6E1 treatment (containing 100% soybean meal and 262 kcal 100 g-1 diet) and P5E1 treatment (containing 80% soybean meal and 262 kcal 100 g-1 diet). Also the highest survival rate of the shrimps was observed in the P1E1, P1E2, P3E3 and P5E3 treatments. Additionally interactive effect of different protein ratios and energy levels had significant difference on body protein, fat, fiber and ash contents (P<0.05). Results of the present study suggest the possibility replacement of at least 80% of dietary fish meal by soybean meal in the diet of pacific white shrimp in the conditions of southern part of Iran.

Studies on the nutritional value of cassava (Manihot utillisima) peels as energy source in the diet of Oreochromis niloticus fry fed in indoor glass aquaria

This study, though, has as its core objective cost reduction in aquaculture nutrition was equally designed to investigate the value of the peels of cassava (Manihot utillisima) as energy source in the diet of Oreochromis niloticus fry. Three levels of cassava peels diet and a control (100% yellow maize in the carbohydrate mixture) was prepared and tested on O. niloticus fry for ten (10) weeks. The fry with mean weight of 0.32g were grouped fifteen (15) in each of the glass aquaria measuring 60x30x30cm with a maximum capacity of 52 litres of water. The fry were fed twice daily at 10% biomass. Weekly, the fry were weighed to determine the weight increment or otherwise and the quality of feed adjusted accordingly. Water quality parameters like temperature, pH and dissolved oxygen (D.0) were monitored and found to be at desirable level. DT 3 (97 % cassava peels and 3% yellow maize) in the carbohydrate mixture gave the best growth performance. The fry fed, this diet gained mean weight of 1.18g for the period of the experiment. However, the poorest performance in terms of growth was from fry fed the control diet (100%yellow maize in the carbohydrate mixture) fry fed this diet gained mean weight of 0.80 for the duration of the experiment. Analysis of the various growth indices like SGR, PER, FCR and NPU shows that DT3 was the overall best diet with an SGR value of2.40 and FCR of 43.83. However, DT 1 (70% cassava peels and 30% yellow maize) gave the poorest SGR of 1.61 and FCR of 67.58. The difference in weight gain among the fry fed the three levels of cassava peels diet and the control was not statically significant (P>0.05)

Study on the reproductive biology of Pinctada fucata (Gould) (Mollusca: Pteriidae)

Annual cycle of gonad development and spawning in pearl oyster, Pinctada ficata (Gould) in Nakhiloo, Northeast Persian Gulf, was investigated over two years from August 1994 to June 1996. Gonadal condition was assessed by staging criteria to describe gametogenic development from histological preparations of randomly collected individuals of all sizes. A bimodal gametogenic pattern with summer and autumn spawning periods was evident throughout the study. Gametogensis commenced in November-December which proceeded by major gonadal maturation during February-April. Summer spawning was observed from April to July with major spawning at the latter end. During spawning peak in July, low level of gametogensis was noticed. Gametogenic activity was picked up again in August-September which proceeded by autumn spawning from September to December. Towards the end of spawning season, incidence of gonadal inactivation increased. Minimum level of gonadal activity was observed in November. Temperature regime appears to have influential role in regulation of gametogenic and spawning processes. Gonadal development and spawning trends were similar in both sexes. P. radiaata was found to be protandrous hermaphrodite which matured as a male at shell height greater than 20 mm. Biseivality was uncommon and the sex ratio was about 1:1. Ultrastructure of gametes were investigated in the Pictada fucata (Gould). "Auxiliary cells" closely accociated with developing oocytes were observed. Each oocyte seems to be associated with only one secretory cell. which is characterized by an abundant rough endoplasmic reticulum at the onset of vitellogenesis. Contact between this cell and a developing oocytes is maintained by a desmosome-like junction which can be observed when the vitelline coat is formed. these "auxiliary or nursing cells" seem to play a tropic role in vitellogenesis, and may be involved in the formation of the vitelline coat of the oocytes. Oocytic degeneration is observed in this species, it is a continuous phenomenon of varing intensity throughout the year. The ultrastructural changes resulting in lysis of the oocyte are described. Mature spermatozoa consist of a broad, cap-shaped acrosomal vesicle, subacrosomal material, a round nucleus, two triplet substructure centrioles surrounded by four spherical mitochondria, and a flagellum anchored to the distal centriole and plasma membrane. Spermatozoa of Plucata closley resemble to those of other investigated Pteriidae. Changes in proximate composition of soft tissue and gonadal cycle of Pinctada fucata was studied. Mobilization and utilization of stored reserves are apparent during gametogenesis and gonadal maturation. Protein reserves are utilized during spermatogenesis while reserved carbohydrates form the main energy donor in oogenesis. The role of lipid as am.: energy reserve is second to that of carbohydrate.

The influence of constant temperature on the embryonic growth of Asellus aquaticus L. (Crustacea) [Translation from: Vestsi Akademii Navuk Belorusskoi SSR, Seriya Biyal. 1979(1) 128-130]

It is known that an adequately large amount of work has been devoted to investigations on the influence of temperature on the growth period of aquatic invertebrates. However, the action of the given factors on the basic biological characteristics of embryonic growth in crustaceans is virtually unknown. An experimental study of the effectiveness of the transformation of matter and energy during the period of embryogenesis in the isopod Asellus aquaticus L. under different constant temperatures was carried out. Specimens were collected in the quarry lakes of the Kurasovshchin zone (city-Minsk). The authors developed a quantitative analysis of the basic energetic properties of animals during one of the physiological stages at different constant temperatures, which allows one to determine the temperature range in which the expenditure of energy, at a given instance during embryonic growth, is minimised. For A. aquaticus this range is represented by the limits 10-22°C, during which the least expenditure of energy is observed between 14.5 and 18.8°C.

Aspects of the washout of salmonid eggs. 1. Observations on the physical characteristics of real and artificial eggs, their rate of fall in a water column and their pattern of settlement in an experimental channel

When salmonid redds are disrupted by spates, the displaced eggs will drift downstream. The mean distance of travel, the types of locations in which the eggs resettle and the depth of reburial of displaced eggs are not known. Investigation of these topics under field conditions presents considerable practical problems, though the use of artificial eggs might help to overcome some of them. Attempts to assess the similarities and/or differences in performance between real and artificial eggs are essential before artificial eggs can validly be used to simulate real eggs. The present report first compares the two types of egg in terms of their measurable physical characteristics (e.g. dimensions and density). The rate at which eggs fall in still water will relate to the rate at which they are likely to resettle in flowing water in the field. As the rate of fall will be influenced by a number of additional factors (e.g. shape and surface texture) which are not easily measured directly, the rates of fall of the two types of egg have been compared directly under controlled conditions. Finally, comparisons of the pattern of settlement of the two types of egg in flowing water in an experimental channel have been made. Although the work was primarily aimed at testing the value of artificial eggs as a simulation of real eggs, several side issues more directly concerned with the properties of real eggs and the likely distance of drift in natural streams have also been explored. This is the first of three reports made on this topic by the author in 1984.

Effects of stress on the immune system of fish

The effects of stress on the immune system of various fish species including dab Limanda limanda, flounder Platichthys flesus, sea bass Dicentrarchus labrax and gobies Zosterisessor ophiocephalus, were investigated from laboratory and field experiments, using various assays to measure immunocompetence, correlated with histological and ultrastructural observations. Modulation of the immune system was demonstrated at tissue, cellular and biochemical levels following exposure to various stressors. The spleen somatic index was depressed in dab stressed in the laboratory and gobies collected from polluted sites in the Venice Lagoon. Differential blood cell counts consistently showed an increase in phagocytes and decrease in thrombocytes in fish exposed to various stressors. Phagocytic activity from spleen and kidney adherent cells was stimulated in dab stressed by transportation but depressed in fish exposed to chemical pollutants. Respiratory burst activity in phagocytic cells was also stimulated in stressed dab but depressed in sea bass exposed to cadmium. The results are discussed in relation to current concepts on stress in fish and the regulation of the immune system.

Insights into the ecological performance of agroecosystems with ECOPATH II

The article provides insights on agroecosystem modeling and analysis with ECOPATH II.

Preliminary note on the biochemical composition of meat of dai (Chirocentrus spp) and kati (Opisthopterus spp)

Studies were taken up biochemical composition of Chirocentrus dorab and Opisthopterus sp. The seasonal changes, yield of mince and energy value of the meat were also reported.

A note on the calorific values of a freshwater teleost, Labeo gonius (Hamilton)

Forty specimens of Labeo gonius (Ham) were analysed for protein, carbohydrate and fat values. The calorific value was calculated by multiplying the value of protein and carbohydrate with the energy factor 4.1 and for fat by 9.3. The average calorific values of fish for protein, carbohydrate and fat were 72.16, 9.55 and 11.90 cal/100 g respectively suggesting that the fishes are highly nutritious.