bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sobolev spaces and the Cayley transform
Authors: Astengo Francesca , Di Blasio Bianca 
Published: January 2006

The generalised Cayley transform

C

\mathcal {C}

from an Iwasawa

N
N

-group into the corresponding real unit sphere

S

\mathbb {S}

induces isomorphisms between suitable Sobolev spaces

H

α

(

S

)

\mathcal {H}^\alpha (\mathbb {S})

and

H

α

(
N
)

\mathcal {H}^\alpha (N)

. We study the differential of

C

\mathcal {C}

, and we obtain a criterion for a function to be in

H

α

(

S

)

\mathcal {H}^\alpha (\mathbb {S})

.
An air‐economizer apparatus for use in fish work
Authors: Abram F. S. H. 
Published: January 2006

Cylinders of compressed air are usually employed to aerate fish stock tanks located away from a source of mains electricity.The apparatus described drives a compressor by extracting some of the energy contained within the high‐pressure air from the cylinder by expanding it through an engine, and recovering the power produced. The compressor draws air from the atmosphere to supply a reservoir used to aerate the tanks, at about 0–2 atmospheres. The volume of air obtained is five to six times that available when an air cylinder is connected direct to the aeration system.
Feeding and digestion in two cottid fishes, the freshwater Cottus gobio L. and the marine Enophrys bubalis (Euphrasen)
Authors: Western J. R. H. 
Published: January 2006

A comparative study of feeding and digestion in the freshwater Cuttus gobio and the marine Enoghrys bubnlis has been made. The digestion of live prey taken voluntarily, and of aqueous starch suspensions and of olive oil administered by stomach tube, are described at the macroscopic and histological level. Particular attention has been paid to the food capacity of the gut, the mechanical treatment of the food, and the role of mucus in the alimentary tract.Digestion, which is similar in the two species, is divided into three distinct phases, corresponding to the three morphologically separate regions of the post‐pharyngeal gut. The relative roles of each of the three regions in the digestion and absorption of food are assessed.No modification of gut structure or function in either species directly attributable to environmental salinity has been detected. The evidence suggests that the faster growth rate of the marine species may be due to the greater digestive‐absorptive capacity of its digestive system.
An investigation of the advantages of autumn and spring stocking with brown trout Salmo trutta L. in a Yorkshire reservoir
Authors: Templeton R. G. 
Published: January 2006

Batches of trout have been introduced into Chelker Reservoir in Yorkshire in the autumn and spring since the 1870's for angling purposes. Six batches of tagged, hatchery‐reared brown trout Salmo trutta L. were introduced from autumn 1966 to spring 1969. During the angling season fish introduced in the spring give better catches than those stocked in the autumn. At the beginning of the season the larger fish in the spring batch are caught more often than the smaller fish from the same batch. The larger fish in the autumn batch are caught more often than the smaller fish from that batch throughout the season. The population, available to the angler from the shore was estimated to be 1491 in 1968, with 722 fish/km of shoreline. More fish survive to a second year in the reservoir than is apparent from the number of tags returned. Fish introduced in the spring usually begin growing before those introduced in the autumn, thereafter growth rates varied. The growth rate was independent of the number offish stocked up to the numbers put in.Batches of tagged trout were retained at the hatchery up to nine months to gain relevant experience of post‐tagging mortalities, tag loss rate and effect of tags on growth.
Intraspecific communication in goldfish
Authors: Timms A. M. 
Published: January 2006

Part I. Characteristics of locomotor behaviour of goldfish (Carassius auratus) were monitored automatically and the response to sensory cues provided by conspecifics was analysed. Goldfish were attracted to free‐swimming conspecifics and oriented to them klinokinetically by decreasing their mean angle size of turns and increasing both their turning frequency and mean step length between turns. These locomotor changes were stimulus bound. Although the responses were mediated visually, blinded goldfish, which were not overtly attracted, nevertheless oriented orthokinetically to non‐visual cues from the conspecific. Part II. Simulation of the conspecific by models demonstrated that oval and horizontal rectangular shapes of the same area and their size interactions, elicited significant attraction whereas square and vertical rectangular shapes of the same area did not. Increasing speeds and/or size of the model tended to bring about stronger attraction.
Haematological effects of stress on a teleost, Esox lucius L.
Authors: Soivio Antti , Oikari Aimo 
Published: January 2006

Stress produces a haemoconcentration, elevated blood lactate, increased glucose concentrations and alters the plasma electrolyte balance in two groups (brackish‐ and freshwater) of the northern pike, Esox leucius L., after one month's starvation. A method for dorsal aorta catheterization and a receptacle for cannulating fish is described.The blood glucose level of the freshwater pike was twice that of the brackish‐water group, and the plasma sodium and magnesium concentrations in the brackish‐water pike were significantly higher. The haematocrit, haemoglobin and blood lactic acid concentrations were higher in freshwater pike. The plasma potassium and calcium concentrations in the two groups did not differ.Haemoconcentration due to stress by handling for 1.5 min was shown by changes in haematocrit and haemoglobin values. The haemoglobin concentration returned to normal in freshwater pike after 4 h but in brackish‐water pike after 12 h.As a result of handling, the blood lactic acid level rose steeply and required 12 h to return to normal.The blood glucose concentration rose to its maximum value within 1 h of handling and required two days to return to normal.The plasma sodium level remained stable after handling, but the potassium level was erratic. In brackish‐water, the potassium concentration of the pike remained high for 12 h after stress, but in the freshwater group, after a rise, the concentration fell to below the initial level within 4 h. The changes of the potassium concentrations in relation to sampling time are discussed. The changes in the divalent ion concentrations were marked and similar in the two groups; with an increase lasting 1–4 h and then a fall below the initial level, which was regained after two days.
Sea trout in North Argyll Sea lochs, population, distribution and movements
Authors: Pemberton R. 
Published: January 2006

Sea trout were sampled by shore seining in the sea lochs of the west coast of Scotland between 1970 and 1974, This area is of special interest because of the indentation of the coastline and the varying degree of freshwater and marine influence in the sea lochs. The majority of fish caught were in their first year after smolt migration. These post‐smolts were caught mainly in May and June, after which the number of trout present was low until fish at the ‘whirling’ stage appeared in the catches at the end of August, continuing through to the following spring. An additional recruitment of mainly unsilvered young trout from the rivers to the sea lochs was found in the autumn. Age and sex composition of both spring and autumn recruits, and of mature fish, were investigated and compared.A total of 3228 sea trout were tagged, with 311 recaptures. These recaptures supported the evidence from smolt trapping and beach seine catches that, in the first post‐migration year, the smolts migrate from the rivers from late March to early May, they then migrate from the sea lochs in May and June and return in late summer and autumn.
The effects of hypophysectomy, prolactin therapy and environmental calcium on freshwater survival and salinity tolerance in the brown trout Salmo trutta L.
Authors: Oduleye S. O. 
Published: January 2006

Hypophysectomy resulted in a loss of ability of the euryhaline salmonid, Salmo trutta to survive in fresh water. The mean survival time was 4–5 days. Maintenance in a medium containing 5 mM calcium increased the mean survival time to 8 days while 10 mM decreased it. Injection of 0–21.U./gm prolactin enabled hypophysectomized fish to survive the 2‐week duration of the experiment.High environmental calcium, or pre‐adaptation to a medium of high calcium, increased salinity tolerance of the brown trout probably by promoting a quick return of plasma electrolyte concentration to normal after transfer to sea water.
Effects of anaesthesia with MS 222, neutralized MS 222 and benzocaine on the blood constituents of rainbow trout, Salmo gairdneri†
Authors: Soivio Antti , Nyholm Keijo , Huhti Marja 
Published: January 2006

Rainbow trout (Salmo gairdneri Richardson) were subjected to 15 min anaesthesia with unbuffered MS 222, neutralized MS 222 and benzocaine with and without physical stress. Blood samples were taken through cannulae inserted into the dorsal aorta. The Hct values and Hb concentrations increased with all the anaesthetics, which also caused swelling of erythrocytes. The initial values were restored within 4–12 h of recovery. Each anaesthetic elevated the blood lactate concentration, but the initial level was regained within 12 h. The blood glucose level decreased the most during anaesthesia with unbuffered MS 222, but the initial level was rapidly restored. Benzocaine caused the least hypoglycaemia during anaesthesia, but the subsequent hyperglycaemia, as in the fish anaesthetized with neutralized MS 222, lasted 24 h. Neutralized MS 222 and benzocaine elevated the plasma K + concentration more rapidly than unbuffered MS 222. The initial levels were regained in 4 days. All anaesthetics raised the Mg ++ concentration.The Po2 in the dorsal aorta decreased during anaesthesia with unbuffered MS 222 by about 85 mmHg, while the Pco2 increased by about 1.5 mmHg. Their initial levels were regained within 20 min. During anaesthesia the pH value decreased by 0.3 units and returned to the initial value within 2–4 h of recovery. MS 222 seemed to be an asphyxiant.
Reproductive biology, length‐weight relationship and relative condition of Tilapia leucosticta (Trewavas) in Lake Naivasha, Kenya
Authors: Siddiqui Abdul Q. 
Published: January 2006

In Lake Naivasha Tilapia leucosticta (Trewavas) spawns throughout the year. Males attain maturity at 180 mm and females at 160 mm total length. Males predominate over females in the catches (sex ratio 1‐00 : 0‐51). Fecundity ranged from 320 to 1328 eggs with an average of 751. The relationship between fecundity (F) and total length (L), body weight (W) and gonad weight (GW) is:

image
The length‐weight regression coefficient is near to the cube. There is little seasonal fluctuation in relative condition of the fishes.
The population biology of two species of eyefluke, Diplostomum spathaceum and Tylodelphys clavata, in roach and rudd
Authors: Burrough R. J. 
Published: January 2006

Infections of roach (Rutilis rutilus), and rudd (Scardinius erythrophthalmus), by the eyeflukes Diplostomun spathaceum and Tylodelphys clavata were studied in a lake over a three year period. T. clavata first appeared at the beginning of the study. Roach were heavily infected by both parasites, whereas the rudd contained very few specimens of either species. A small number of roach‐rudd hybrids were also examined, and appeared to have a susceptibility intermediate between the parental types.Levels of T. clavata in roach increased throughout the study. This parasite had a life span of a year or less in the fish, and was continuously lost from the population. This loss was balanced by a minor infection period in April/May and a major one extending from August until January. The fish continued to accumulate infections until they reached a size of about 130 mm, but thereafter intensity fluctuated about the level reached. D. spathaceum infections similarly increased throughout the period of study, and there was a suggestion of a wave of infection in the spring. This parasite has a much longer life span, and levels of infection increased with fish size, only falling in the largest, and therefore oldest, hosts.The major changes in the parasite populations in the roach were reflected, to a lesser extent, in the rudd. Both species were over‐dispersed, but the data from roach was too heterogeneous to fit to any theoretical models, whereas that from the rudd was found to conform to a Negative Binomial distribution.
Observations on development and morphological effects of histamine liberator 48/80 on PAS‐positive granular leukocytes and heterophils of Catostomus commersoni
Authors: Barber D. L. , Westermann J. E. Mills 
Published: January 2006

Developmental stages of the two circulating blood granulocytes, the heterophil and the periodic acid‐Schiff‐positive granular leukocyte (PAS‐GL) are described. There are no metachromatic basophils in this fish and eosinophils, when present, are confined to extra‐vascular tissues. Fish were killed up to 24 h after injection with histamine liberator 48/80. Morphological (L/M and E/M) and histochemical studies of blood, haemopoietic tissue and gills from experimental fish were compared with those of untreated control fish.Blood cells other than PAS‐GL and heterophils were generally unaffected by 48/80. Most PAS‐GL and heterophils showed alterations in granules and other cytoplasmic features. Stretching and splitting of the PAS‐GL nucleus occurred. Very little, if any, histamine was detectable in PAS‐GL and heterophils.The authors support the postulate that during evolution PAS‐GL become basophils/ mast cells through two major stages, (1) sulphation of the granule polysaccharide to give heparin resulting in metachromasia of the granules and (2) storage of large quantities of histamine in the granules.
The use of telemetry to study light synchronization with feeding and gill ventilation rates in Salmo trutta
Authors: Oswald R. L. 
Published: January 2006

A technique is described whereby the electromyogram of the m. adductor mandibulae of brown trout is detected by implanted extracellular electrodes and used as the input signal for an ultrasonic transmitter attached externally to the fish. The periodic electrical activity of the muscle during ventilation is relayed by the transmitter using an analogue pulse system.As the ventilatory electromyogram occurs in discrete rhythmic trains, it follows that alterations to this rhythm can be used to telemeter, instantaneously, single feeding events from a free swimming fish. Laboratory tests have shown that the feeding act is unequivocally distinct electromyographically from other manoeuvres such as ‘coughing’.Four adult brown trout have been equipped with this transmitter system and released in Airthrey Loch, Stirling. Using a tracking facility, feeding activity and ventilatory rhythms have been recorded for extended periods.The results indicate the presence of three daily peaks of feeding activity, which is discussed in relation to changes in light levels. The telemetry records indicate that night feeding is a common occurrence in brown trout. In addition, ventilatory rates were found to be at or near resting levels.
Studies on the relationship between osmotic or ionic regulation and thyroid gland activity in two salmonid fishes, Salmo gairdneri Richardson and Oncorhynchus kisutch Walbaum
Authors: Milne R. S. , Leatherland J. F. 
Published: January 2006

In freshwater‐acclimated rainbow trout a single intraperitoneal injection of ovine TSH significantly elevated plasma thyroxine (T4) levels within 1 h after the injection. In seawater adapted trout the increase in T4 after TSH‐treatment was not evident until 6 h after the injection. TSH caused a transient fall in plasma Na+ and Cl‐ between 3 h and 9 h after the injection in seawater‐adapted fish and plasma Na+ was lowered in freshwater‐adapted trout 24 h after the injection. Although there were clear histological changes in the thyroid gland of freshwater‐adapted trout after TSH‐injection, no such changes were evident in seawater‐adapted fish.Plasma thyroid hormone levels and thyroid histology in freshwater‐adapted rainbow trout and coho salmon transferred to sea water, and seawater‐adapted trout transferred to fresh water showed no consistent changes compared with controls.The data are interpreted to indicate that although ambient salinity may have indirect effects on thyroid activity there is no direct involvement in ionic or osmotic regulation in the two species.
The eye lens weight and age in the common carp, Cyprinus carpio L.
Authors: Crivelli A. 
Published: January 2006

The validity of the use of the weight of dried eye lenses as an indicator of age in the common carp, Cyprinus carpio L., is tested. There is a significant difference between males and females for fish of two and three years old. Otherwise no significant difference is noted between sexes. The linear relationship between the dry weight of eye lenses and age + 1 are: In Y+ 1= 0.5202 + 16.4928X (r= 0.93) for female and ln Y+ 1=0.4276 + 16.7364X (r= 0.94) for male.The method for determining age is valuable for fish until three years old. However for older fish, in spite of a correlation coefficient between lens weight and age and even with a significant difference between annual groups, the age determination may be misleading due to the overlap in lens weights. In conclusion therefore this method may not be useful for back calculation of growth, for production estimates or studies in which accurate estimates of age are needed.
The ultrastructure of the atrial myocardial cell in three teleostean species
Authors: Leknes I. L. 
Published: January 2006

The atrial myocardial cell in three teleostean species Gadiculus thori J. Smith, Melanogrammus aeglefinus (L.) and Onos cimbrius L. is described. The contractile material is located in the periphery of the cell, whereas the nucleus and mitochondria occupy the central part. The tubules of the sarcoplasmic reticulum are of larger diameter at the Z‐band levels than elsewhere in the sarcomere. The transverse part of the intercalated disc is composed of alternating desmosomes and intermediate junctions. In the longitudinal part of the disc desmosomes occur, situated in close proximity to Z‐bands. Short nexuses were found in the longitudinal part of the disc, usually near the transverse part. In G. thori numerous atrial specific granules were seen. A high number of mitochondrial granules and glycogen granules seems to occur in O. cimbrius. In the atrial myocardial cell of two or six day‐old larvae of M. aeglefinus. the contractile material is organized into thin myofibrils, and numerous ribosomes are located in the sarcoplasm.The results of the present work are compared to those previously described in the teleostean atrium and ventricle. The differences in the heart structure within the gadoid family are discussed from a functional and an evolutionary point of view.
Effects of bovine growth hormone on plasma FFA concentrations and liver, muscle and carcass lipid content in rainbow trout, Salmo gairdneri Richardson
Authors: Leatherland J. F. , Nuti R. N. 
Published: January 2006

Bovine growth hormone (GH) given daily to rainbow trout, Sulmo gairdneri for 4 or 7 days at either 10.00 or 14.00 hours, significantly increased plasma free fatty acid (FFA) levels but had not effect on plasma cholesterol levels. Liver lipid content of the GH‐injected trout after seven injections was significantly lower than comparable controls in groups injected at both 10.00 and 14.00 hours. There were no apparent effects of GH on carcass or muscle lipid content although in fish injected and sampled at 14.00 hours there was a significant correlation between the number of injections and carcass lipid content.Changes in hepatosomatic index (HSI), liver, muscle and carcass lipid content, plasma FFA and cholesterol concentrations and somatotrop activity during food‐deprivation for up to 60 days are described. Despite significant decreases in liver and muscle lipid content and increases in plasma FFA levels in food‐deprived fish, there was no concomitant change in apparent somatotrop activity.The data are interpreted to indicate that although exogenous GH, in the doses used here, appears to stimulate mobilization of lipid reserves, particularly from the liver, there is no evidence that enforced changes in lipid reserves elicits a response of the endogenous somatotrop cells.
Comparison of bottom trawl stock densities in the inner Kavirondo Gulf of Lake Victoria
Authors: Muller R. G. , Benda R. S. 
Published: January 2006

A comparison of mean bottom trawl stock densities (kg ha‐1) from 19 UNDP 1969/70 tows, 69 EAFFRO 1975 tows and 167 fourth quarter FFRI 1977 tows in the inner Kavirondo Gulf of Lake Victoria showed the following changes from 1969/70 to 1977.

A reduction in mean stock densities for Bagrus docmac, Clarias mossambicus, Haplochromis spp., Protopterus aethiopicus, Schilbe mystus and Synodontis spp.
An increase in mean stock densities for Lates niloticus, Tilapia nilotica and T. variabilis.
No change in mean stock density for Labeo victorianus.
No T. esculenta or Mormyrus kannume collected in 1977.
Some age related changes of adult rainbow trout, Salmo gairdneri Rich., peripheral erythrocytes separated by velocity sedimentation at unit gravity
Authors: Lane H. C. , Weaver J. W. , Benson J. A. , Nichols H. A. 
Published: January 2006

Velocity sedimentation at unit gravity separated peripheral erythrocytes of adult rainbow trout according to age and size. The cells located at the top of the gradient contained numerous polyribosomes, few mitochondria and an essentially electronlucent nucleus. The cells at the bottom of the gradient no longer contained these cytoplasmic organelles and had an essentially electron‐dense nucleus. The middle of the gradient contained cells with either very few polyribosomes or cells devoid of this organelle.The length, width and mean corpuscular volume (MCV) of the average cell increased and the width to length ratio decreased progressively from the top of the gradient to the bottom.No Statistical significance could be determined in the changes of the mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) although they appeared to follow theoretical projections.The use of haematocrit, red cell count, haemoglobin concentration, MCV, MCH and MCHC in assessing erythropoietic activity and the size and haemoglobin content of the maturing cell is discussed.