bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of food on the growth of carcase, liver and ovary in female Gasterosteus aculeatus L.
Authors: Allen J. R. M. , Wootton R. J. 
Published: January 2006

The effect of ration size on the growth of the carcase, liver and ovary in female three‐spined sticklebacks, Gasterosteus aculeatus L., was studied experimentally at monthly intervals throughout the annual reproductive cycle. Temperature and photoperiod during each experiment corresponded to the average, natural conditions for that month.Growth of the carcase was sensitive to ration in all months. At a given ration, the growth rate of the carcase was relatively constant. The water content of the carcase was inversely correlated with ration size. Growth of the liver was also sensitive to ration, but the sensitivity varied in different phases of the reproductive cycle. High rates of weight loss occurred in the liver under starvation, but at maximum rations the liver showed high rates of weight gain particularly in the post‐spawning period. Growth of the ovary was relatively insensitive to ration but directly reflected the changes occurring naturally in the reproductive cycle.It is suggested that the liver acts as a buffer between the carcase and the ovary and this helps to insulate the ovary from the immediate effects of fluctuations in food supply.The growth rates of the carcase and liver may provide useful indices of the rate of food consumption in natural populations. Although, if the liver is used, its growth has to be interpreted in the context of the annual reproductive cycle.
Duration of gut passage and its dependence on temperature and food consumption in roach, Rutilus rutilus L: laboratory and field experiments
Authors: Hofer R. , Forstner H. , Rettenwander R. 
Published: January 2006

A laboratory method is described by means of which gut passage time as a function of temperature, diet and consumption rate is investigated in roach, an omnivorous cyprinid. Rates of food passage are accelerated by increasing temperature and food consumption. Equations for the regressions between gut passage time and consumption rate at four temperatures are given. Animal food causes a delay in gut passage time. In adult roach (30‐100 g body weight) gut passage time was found to be independent of size.A field method was also developed which allows the direct estimation of gut passage time and consumption rate in natural fish populations. The results of experiments with this field method agree with those of laboratory experiments.
Effect of dietary quality on the gastric evacuation and intestinal passage in Sarotherodon mossambicus (Peters) fry
Authors: De Silva S. S. , Owoyemi A. A. 
Published: January 2006

The gastric evacuation time (GET) and the passage of food through the intestines was investigated in Sarotherodon mossambicus (Peters) fry of two size groups, viz. 0·2–1·0g and 1·0–3·0g, in response to five diets. In the experiments voluntary feeding was adopted and markers were not used. The passage of food through the stomach was described by the exponential model.The GET increased with body weight for any particular diet, with one exception. The GET ranged from 290 min to 1104 min in fry of 1·0–3·0 g on Diet 2. There was evidence to indicate that the GET was negatively correlated to the specific gravity of the diet.The passage of food through the intestines showed a consistent trend from diet to diet; e.g. the algal diet being moved into the intestine in ‘finite’ quanta as opposed to the others. The importance of these observations and the implications of the dependence of the GET on the specific gravity of the diet in the use of markers in digestibility studies are discussed.
Spawning of the Australian freshwater fish Murray cod, Maccullochella peeli (Mitchell), in earthen ponds
Authors: Rowland S. J. 
Published: January 2006

Murray cod, Maccullochella peeli, spawned naturally in earthen ponds in four consecutive breeding seasons. Spawning was induced by a rise in water temperature up to or above 20°C during spring, however, an associated rise in water level was not required. Response to the temperature rise was more rapid later in the season and increasing daylength may have also been involved. Eggs were deposited on firm substrates at depths between 0·5 and 2·3 m, and hollow pipes, logs or similar structures were not necessary to provide suitable sites for egg deposition. At two spawning sites, mud had been removed from the pond banks by the broodfish and the eggs attached to the exposed clay. At one spawning site, a male cod was observed protecting the eggs during incubation.It is suggested that high survival of cod larvae will only occur when a significant rise in water level coincides with the breeding season and as a consequence the control of water levels for irrigation and flood mitigation purposes during spring and summer has affected Murray cod to a greater extent than golden perch, Macauaria ambigua, which spawns only after a substantial rise in water level, when conditions are more favourable for larval survival.
Food and feeding habits of the lesser spotted dogfish, Scyliorhinus canicula (L.), in Isle of Man waters
Authors: Lyle J. M. 
Published: January 2006

Stomach contents of the lesser spotted dogfish, Scyliorhinus canicula, from Isle of Man waters were investigated. Dogfish fed opportunistically on a wide range of macrobenthic fauna with hermit crabs, cockles and whelks the dominant prey. Items of secondary importance included various crabs, callianassid shrimps, bivalve molluscs, holothurians, polychaetes and, when locally abundant, herring, Clupea harengus. Dogfish predated more heavily on molluscs than reported in previous studies, reflecting the abundance of molluscs in the associated benthic community.Composition of the diet altered gradually with dogfish size, reliance on small crustaceans declined and consumption of hermit crabs and molluscs increased with growth. Seasonal changes in the composition of the diet were observed. Feeding intensity was greatest during summer, related in part to increased prey availability, and was least during autumn.
Temporal changes in fat and protein levels in the tropical Anabantid Trichogaster pectoralis (Regan)
Authors: Hails A. J. 
Published: January 2006

Samples of a wild population of the Anabantid Trichogaster pectoralis (Regan) were taken during and after one of the two main breeding periods of the year. Carcasses of both sexes and female gonads were analysed for fat, protein and carbohydrate. Carbohydrates were present in insignificant amounts in all tissues. The fat content of the ovary proved to be high (over 30% of wet weight) and, as a result, ovarian energy in a ripe female formed a substantial proportion of the total energy content of the fish. However, it did appear possible for females to develop large ovaries without depleting the carcass fat stores.Although protein levels in the carcass were significantly higher in 1 month, relative to fat levels, protein levels remained fairly constant during the period of study. Conversely fat levels showed marked fluctuations throughout the breeding period, being high at the start of the breeding period, low towards the end, finally rising again 1 month after most fish had terminated breeding. The range of fat levels appeared to be independent of the gonadal state of the fish at capture and seemed more closely related to month of capture. Two explanations are suggested; (1) changes in food availability over the period in question and/or (2) if repeated spawnings occur this could deplete fat reserves in the carcass.In this species fat is stored largely in the muscle but some is stored around the coiled intestine. A visual scoring system was used to assess the extent of this fat deposition and it was found that the fat score was correlated with the level of fat in the carcass. Thus the level of fat around the intestine, although insignificant relative to carcass fat, could be used as a method of assessing the fatness of a fish.
Influence of body weight and temperature on growth rates of Arctic charr, Salvelinus alpinus (L.)
Authors: Jobling M. 
Published: January 2006

When reared for a period of 6 months at a temperature of 10°C Arctic charr, Salvelinus alpinus, increased in weight from 18 g to approximately 135 g. Specific growth rates decreased as the fish increased in size and the relationship between size and growth rate could be described by the equation:
image

where Gw is specific growth rate and W is fish weight in grams. Temperature effects upon growth were examined using previously published data. Below the optimum growth temperature, the growth rate of a fish of given size could be predicted using the equation:
image

where T is the rearing temperature.Rates of growth of Arctic charr were as high as those reported for other salmonid species reared under similar conditions. Preliminary results suggested that growth rates of charr may be lower in salt water than in fresh water.
Scanning electron microscopy of goldfish, Carassius auratus, intestinal mucosa
Authors: Caceci T. 
Published: January 2006

Scanning electron microscopy was used to examine the intestinal bulb and the caudal portion of the intestine proper of the goldfish, Carassius auratus. The observations made correlated well with previous light microscope studies by other investigators. The mucosal surface of the entire intestine of the goldfish is thrown up into folds, which are oriented along the long axis of the digestive tract in the intestinal bulb, but run more or less transversely in the caudal intestine. Tops of the folds were observed to be rounded or flattened, and the folds themselves formed wavy or zigzagging patterns in the mucosal surface. Numerous mucus‐secreting goblet cells were seen, which were apparently more numerous or more active in the caudal intestine than in the intestinal bulb. The goblet cells are not uniformly distributed throughout the mucosa: they are more evident on the sides of the folds, although occasionally they appear to be located in clusters on the tips.The goblet cells were observed to contain varying amounts of mucous material, and/or to be of different sizes. Although no histochemical tests were performed, the possibility that digestive enzymes known to be present in the intestine may be elaborated by the goblet cells was considered, based on their variable appearance.
Growth and mortality of zebra fish, Brachydanio rerio (Hamilton Buchanan), maintained at two temperatures and on two diets
Authors: Craig J. F. , Fletcher J. M. 
Published: January 2006

One hundred zebra fish per tank were maintained for 112 days at 24°C or 28°C in glass aquaria and fed a diet of flaked food made without cellulose (13.45 kJ g−1, metabolizable energy, Type A) or with cellulose (8.71 kJ g−1, metabolizable energy, Type B). Each experimental condition was repeated in triplicate (12 tanks). The weight of food given daily to the fish was based on daily records of survivors (from which mortality rates were calculated) and wet wt of fish (measured every 14 days) in each tank. All fish were fed with the same weight of food per day and the quantity of energy in the food in excess of standard metabolism (as a proportion of SM) was approximately 0–5 for fish maintained at 28°C and fed food B, 1–0 for fish maintained at 24°C and fed food B, 1–5 for fish maintained at 28°C and fed food A, and 2.2 for fish maintained at 24°C and fed food A.Non‐ionized ammonia, nitrite and nitrate nitrogen in the tanks did not reach toxic levels although there was an increase in total ammonium nitrogen in one tank and a subsequent heavy mortality. It was assumed that this was caused by the build up of pathogenic bacteria. Apart from this tank, mortality was highest in tanks at 28°C with fish fed food A and second highest in tanks at 24°C with fish fed on the same diet. Growth was measured in units of length, wet and dry weights, carbon and energy. There was a good correlation (P < 0.001) between carbon (mgC mg−1) and calorific (J mg−1) values and a conversion factor of 46.2 J (mgC)−1 was derived. Fish maintained at 24°C and fed food A had the highest rates of growth both in weight and in energy value per unit weight. Fish fed the same diet but kept at 28°C had the lowest growth rates. Both these groups of fish had the highest coefficients of variation in wet weights which increased during the experiment, indicating an increase in interaction within the tanks. There was agreement between the energy value of fish sampled for growth and a condition factor based on the length‐weight relationships of fish remaining in the tanks. A correlation (P < 0.05) was found between instantaneous mortality and growth rates for fish between tanks when those maintained at 28°C and fed on food A were ignored.
An automated ultrasonic telemetry system for the assessment of locomotor activity in free‐ranging rainbow trout, Salmo gairdneri, Richardson
Authors: Rogers S. C. , Church D. W. , Weatherley A. H. , Pincock D. G. 
Published: January 2006

A new automated ultrasonic telemetry system for monitoring the swimming activity of adult rainbow trout, Salmo gairdneri, at liberty in the wild is described. The transmitter detects bioelectric potentials (i.e. electromyograms) associated with the contraction of the epaxial myomeres during swimming. Transmitter output is relayed to the signal processing system via submerged hydrophones. The incoming signals represent averaged electromyograms which have been shown in earlier studies to correlate well with swimming activity and concurrent oxygen consumption of rainbow trout in the laboratory.Electromyogram records obtained from rainbow trout released into a small lake and monitored for up to 4 weeks, indicate a fairly regular pattern of elevated midday activity contrasting with periods of relative quiescence during the evening and morning. This midday peak in locomotory activity is the result of an increased feeding activity which is evidently a response to a concomitant increase in the activity of the fish's prey.
Comparison of the surface properties of seven strains of a fish pathogen, Aeromonas salmonicida
Authors: Johnson C. M. , Tatner M. F. , Horne M. T. 
Published: January 2006

Several physical properties related to the surface characteristics of autoaggregating and non‐autoaggregating strains of Aeromonas salmonicida have been investigated. Properties examined included resistance to the bactericidal action of trout serum, adhesion to fish leucocytes and fish cell monolayers in vitro, resistance to phagocytosis by fish leucocytes and the in vivo localization following intraperitoneal injection. For each strain the presence or absence of an extracellular protein A‐layer was investigated and the pathogenicity for brook trout determined.Presumptive A‐layer protein, in the form of a 49 kdal subunit, could be detected only in one of the strains examined. This strain autoaggregated and was the most resistant to serum bactericidal activity. Complement activation by the alternative pathway was thought to be responsible for this heat‐labile bactericidal activity. Three strains that autoaggregated and three that did not had no detectable A‐layer. Autoaggregating strains appeared more adhesive to both fish cell types but all strains were phagocytosed by fish leucocytes to a similar degree. An autoaggregating strain was localized in the spleen. The seven strains were only moderately pathogenic for brook trout, possibly as a result of the challenge system. In view of this, no property investigated could be correlated with greatly increased virulence.
Histological changes in the gill, kidney and liver of Lahontan cutthroat trout, Salmo clarki henshawi, living in lakes of different salinity‐alkalinity
Authors: Galat D. L. , Post G. , Keefe T. J. , Bouck G. R. 
Published: January 2006

Lahontan cutthroat trout thrive in saline‐alkaline lakes, where other trout species often cannot survive. We examined Lahontan cutthroat trout from nine lakes in which salinity and alkalinity ranged from about 90 to 12 000 mg1−1 and 60 to 3500mgl−1 as HCO3− respectively, for sublethal histological changes in gill, kidney, and liver tissues. Gill chloride cell hyperplasia, gill lamellar epithelial separation, kidney glomerular swelling, blood congestion in kidneys, and deposition of hyalin droplets in kidney glomeruli, tubules, and hemopoietic tissues were the histological alterations statistically associated with differences in lakewater chemistry.Deposition of hyalin in kidney tubules was the only histological change judged pathological and whose severity appeared sufficient to jeopardize normal organ function. Differences in lakewater chemistry explained nearly 90% of the variability observed in severity of tubular hyalin degeneration, and SO42− was the ion most positively correlated with increasing tubular hyalin. Our results suggest that Lahontan cutthroat trout will develop slight to moderate hyalin degeneration in kidney tubules if stocked into lakes where salinity and SO42− concentrations equal or exceed 5000 mgl−1 and 2000mgl−1, respectively.
Aspects of the mating behaviour of male mollies (Poecilia spp.)
Authors: Woodhead A. D. , Armstrong N. 
Published: January 2006

The unisexual fish Poecilia formosa (the Amazon molly) reproduces by gynogenesis, a process in which sperm from the males of the host bisexual species activates development of its eggs. Unisexuals live with one of the host species in nature and compete with bisexual females for the males. It was long thought that male discrimination and mate selection established a balance between the unisexual and bisexual populations. Thus, hierarchies of males were set up in which dominant males mated with their conspecific females and subordinates mated with the Amazon molly. Recent evidence suggested, however, that male fish do not discriminate between their own females and the Amazon molly, and that there always are more males available than sexually receptive females of both species.Our findings indicate that male behaviour may be more complex than suggested by either hypothesis. Mate discrimination and courtship behaviour appear to increase with age, so that large males show almost complete preference for their conspecific females, but smaller males will mate with the Amazon molly. In complex groups, small males often dart in and mate with their own females whilst the large males are engaged in courtship activities and defence of territory.
Age, growth and reproductive strategy of the snakehead, Ophicephalus striatus Bloch, from Sri Lanka
Authors: Kilambi R. V. 
Published: January 2006

A total of 281 snakehead‐lula, Ophicephalus striatus, collected between November 1982 and June 1983 from inundated rice fields and swamps in south‐western Sri Lanka were analysed. Age determination by length frequencies and scale annuli revealed six age groups. An asymptotic length of 520 mm was estimated by the von Bertalanffy growth model.The ova were assigned to four developmental stages and a maturity scale was developed for the females. Fast growing 2‐year‐old fish attain sexual maturity. The ovum size frequencies and occurrence of mature and spent fish indicate that this fish spawns during the south‐west monsoon season. Fecundity estimates ranged from 1688 to 7146 ova. Total length and weight are equally useful for predicting fecundity.
The role of female competition in the mating success of two clones of the Amazon molly, Poecilia formosa
Authors: Woodhead A. D. , Carlson C. 
Published: January 2006

Clones of the unisexual fish Poecilia formosa, the Amazon molly, live in the wild in association with their progenitor bisexual species, and compete with them for resources. These resources include food, space and also mates, since the Amazon molly reproduces gynogenetically, a process in which sperm transferred from a male host species activates their eggs. Earlier studies of the adaptive mechanisms that facilitate the coexistence of the bisexual and unisexual forms have focused upon male behaviour, but recent work with another unisexual species, Poeciliopsis, demonstrated that female aggressive behaviour may play an important part in determining the ecological standing of a clone.We have extended our observations to female mating behaviour in two clones in the Amazon molly; clone 1 that does not thrive well under laboratory culture; and clone 2 that is hardy and survives very well. There was no aggression between the clones, nor did the clones show aggression towards females of the bisexual species. However, clone 1 consistently was more successful in the number of mating encounters made with the male; it approached the male more often than clone 2 and fled from the male less often. Males also showed some preference for mating with clone 1 females. If there are physiological differences in the wild clones similar to those seen in the laboratory, the mating advantage of the less robust clone 1 may ensure its continued survival in competition with a more vigorous clone.
Post‐embryonic development of water‐ and airbreathing organs of Anabas testudineus (Bloch)
Authors: Hughes G. M. , Munshi J. S. DATTA , Ojha J. 
Published: January 2006

The development of respiratory surfaces in post‐embryonic stages of Anabas testudineus was studied using morphometric methods on serial sections through the pharyngeal region of specimens obtained by induced breeding of known parentage. The larvae and fry were fixed in glutaraldehyde and osmium tetroxide. In the young stages aquatic respiration was found to be obligatory. The hatchlings come out of the egg membranes about 10 h after fertilization. During the yolk‐sac stages gaseous exchange takes place through the well vascularized skin. The gills start differentiating at about 24 h and become functional at about 39 h. The labyrinthine organs begin to develop after 51 h but the hatchlings do not take an air breath until they reach 13–14 days. The appearance of scales at 11–14 days probably hinders cutaneous respiration and is correlated with the onset of aerial respiration.Morphometric analysis using stereological methods shows high surface: volume ratios for the gills and labyrinthine organs as adaptations to gas exchange function. A marked decrease in surface: volume ratio for the suprabranchial cavities between 7 and 11 days indicates an increase in volume to accommodate the expanding labyrinthine plates which retain a fairly constant surface: volume ratio.
Observations on granulocyte peroxidase in New Zealand freshwater eels, Anguilla species
Authors: Hine P. M. , Wain J. M. , Dunlop D. M. 
Published: January 2006

Peroxidase activity in the granulocytes of eels was investigated using o‐tolidine, paraphenylene‐diamine‐pyrocatechol, and 4‐chloro‐l‐naphthol as substrates, and cyanide, azide and aminotriazole as inhibitors. Most circulating neutrophils of Anguilla australis Richardson, 1848 and A. dieffenbachii Gray. 1842 showed no peroxidase activity at pH 7.6 and pH 9.0, but a few neutrophils, thought to be mature, were positive. Another granulocyte in the anterior kidney, spleen, parasitized gill tissue and, rarely, the blood contained a cyanide‐resistant, azide‐inhibited, peroxidase and was tentatively identified as the eosinophil. Neutrophils of A. anguilla (L.) showed granular peroxidase activity which was inhibited by cyanide. The eosinophil was not observed.Absence of peroxidase from most circulating neutrophils in A. anguilla and A. dieffenbachii, and its pattern in the neutrophil precursors and mature neutrophils of A. anguilla, may be due to two morphologically indistinguishable granule types. Primary peroxidase‐negative granules occur in precursors and immature neutrophils and secondary peroxidase‐positive granules in mature neutrophils of all three eels. Circulating neutrophils in New Zealand eels seldom mature and are theretore peroxidase‐negative, whereas A. anguilla neutrophils are mature and are usually peroxidase‐positive.Impairment of microbicidal activity in neutrophils lacking peroxidase is discussed.