Contribution of haematological factors to the distributions and estimation of Eustrongyliides africanus larvae densities in Clarias gariepinus and Clarias anguillaris from Bida floodplain of Nigeria

The contributions of hematological factors to the distribution and estimations of Eustrongylides africanus larvae densities in Clarias gariepinus and C. anguillaris of Bida floodplain of Nigeria were documented for the first time. The hematological factors making the most important contributions to the distributions of E. africanus larvae infections in clarias species are mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin (MCH), mean corpuscular volume (MCV) and neutrophils count, in descending order of magnitude; having the manifestations for the months of January, March, September, and December of the year being closely related. Five haematological factors (neutrophils, lymphocytes and eosinophils counts; MCH and MCV) having positive or negative correlation coefficient (r) between 0.50 and 0.85 contributed to the estimated of E.africanus larvae densities in the wild population of Clarias species

Eggs of British Meniscus midges (diptera;dixidae) observed by scanning electron microscopy

The egg of Dixella martinii is described for the first time. The eggs of the Dixidae are placed in three morphological groups: bulbous and meshed; streamlined and smooth; streamlined and minutely spiculated. Ten of the fourteen species known from Britain are placed in these groups. After a detailed description of the egg of D. martinii, the three morphological groups are described and scanning electron micrographs are provided.

A simple method for counting bacteria with active electron transport system in water and sediment samples [Translation from: Kiel. Meeresforsch. 31(2) 83-86, 1975]

Description of a simple method for counting bacteria with active electron transport systems in water and sediment samples. Sodium succinate, NADH and NADPH served as electron donors. It is possible to see several sites of electron transport in the larger cells. Especially impressive are the plankton-algae, protozoa, and small metazoa. This is a partial translation of the ”method” section only.

Demersal groundfish densities in trawlable and untrawlable habitats off Washington: implications for the estimation of habitat bias in trawl surveys

Demersal groundfish densities were estimated by conducting a visual strip-transect survey via manned submersible on the continental shelf off Cape Flattery, Washington. The purpose of this study was to evaluate the statistical sampling power of the submersible survey as a tool to discriminate density differences between trawlable and untrawlable habitats. A geophysical map of the study area was prepared with side-scan sonar imagery, multibeam bathymetry data, and known locations of historical NMFS trawl survey events. Submersible transects were completed at randomly selected dive sites located in each habitat type. Significant differences in density between habitats were observed for lingcod (Ophiodon elongatus), yelloweye rockfish (Sebastes ruberrimus), and tiger rockfish (S. nigrocinctus) individually, and for “all rockfish” and “all flatfish” in the aggregate. Flatfish were more than ten times as abundant in the trawlable habitat samples than in the untrawlable samples, whereas rockfish as a group were over three times as abundant in the untrawlable habitat samples. Guidelines for sample sizes and implications for the estimation of the continental shelf trawl-survey habitat-bias are considered. We demonstrate an approach that can be used to establish sample size guidelines for future work by illustrating the interplay between statistical sampling power and 1) habitat specific-density differences, 2) variance of density differences, and 3) the proportion of untrawlable area in a habitat.

Effect of analytical conditions in wavelength dispersive electron microprobe analysis on the measurement of strontium-to-calcium (Sr/Ca) ratios in otoliths of anadromous salmonids

The use of strontium-to-calcium (Sr/Ca) ratios in otoliths is becoming a standard method to describe life history type and the chronology of migrations between freshwater and seawater habitats in teleosts (e.g. Kalish, 1990; Radtke et al., 1990; Secor, 1992; Rieman et al., 1994; Radtke, 1995; Limburg, 1995; Tzeng et al. 1997; Volk et al., 2000; Zimmerman, 2000; Zimmerman and Reeves, 2000, 2002). This method provides critical information concerning the relationship and ecology of species exhibiting phenotypic variation in migratory behavior (Kalish, 1990; Secor, 1999). Methods and procedures, however, vary among laboratories because a standard method or protocol for measurement of Sr in otoliths does not exist. In this note, we examine the variations in analytical conditions in an effort to increase precision of Sr/Ca measurements. From these findings we argue that precision can be maximized with higher beam current (although there is specimen damage) than previously recommended by Gunn et al. (1992).

Estimations of maximum sustainable fish yields and stocking densities of inland reservoirs of Sri Lanka

The Maximum Sustainable Yields of all fish species for 9 man-made reservoirs in Sri Lanka were calculated by the simplified version of Schaefer Model. The relationship between the Maximum Sustainable Yield (MSY) and Morpho-edaphic Index, (MEI) for Sri Lankan reservoirs was found to be: Log sub(e) MSY = 0.9005 log sub(e) MEI + 1.9220. MSY for these reservoirs were estimated using this relationship. The number of Tilapia) juveniles needed to be recruited to the fisheries of some reservoirs in addition to the present recruitment to increase the fish production to the level estimated by MEI relationship were calculated mathematically.

Culture potentials of gulsha (Mystus cavasius) in management under different stocking densities

PLEASE ALSO CHECK THE FULL TEXT ABSTRACT. Semi-intensive grow-out trials on monoculture of gulsha (Mysrus cavasius) were conducted to assess the production potentials for the period of six months from March through August 2002. Three stocking densities such as 40,000 (T-1), 50,000 (T-2) and 60,000/ha (T-3) were tested in three replications. The production of gulsha was 1,~·74±52, 1,535±71 and 1,370±60 in treatment-I, 2 and 3, respectively and they were significantly different (p

Monoculture of climbing perch, Thai koi, Anabas testudineus (Bloch) under different stocking densities at on-farm

An on-farm trial was undertaken in nine earthen ponds (400 to 640m2) to evaluate the growth and production potentials of climbing perch, Thai koi (Anabas testudineus) for the period of four months from March through June 2006. Three stocking densities such as 75,000 (T1), 100,500 (T2) and 125,000/ha (T3) were tested with three replications. Fish were fed with commercial (SABINCO) pelleted feed (35% crude protein). Fish productions obtained in three treatments such as T1, T2 and T3 were 6,480±217, 6,384±154, 6,617±187 kg· 1ha, respectively. The results demonstrated higher mean growth in T1 than in T2 and T3. However, the net benefit was achieved Tk. 7,26,975 from T1, where the stocking density was 75,000/ha.

Polyculture of carps using over-wintered fingerlings under different stocking densities

An on-farm trial was undertaken in twelve earthen ponds (1200-1600 m') to evaluate the growth and production of over-wintered fingerlings of rohu (Labeo rohita), catla (Carla catla) and mrigal (Cirrhinus rnrigala) in polyculture at three stocking densities. The stocking densities were 2,250; 3,250 and 4,250 fish/ha in treatment-1, treatment-2 and treatment-3, respectively. Fish in all ponds were fed with rice bran and mustard oil cake at the ratio of 3:1. Fish production obtained in three treatments were 2325±74.75, 2620±49.66 and 2982±171.52 kg/ha. The results demonstrated higher mean growth in T-1 than in T-2 and T-3. However, the highest production as well as net benefit was obtained in treatment-3.