bluuebunny/crossref_metadata_2025 huggingface dataset:
Lesions observed in the testis of precociously maturing male Atlantic salmon, Salmo salar L.
Authors: Laird L. M. , Wilson A. R. , Holliday F. G. T.
Published: January 2006

Abnormalities were detected in the testes of maturing male Atlantic salmon parr from one hatchery. They consisted of a focal necrosis of germ tissue at the time of rapid cell division when normal germ cells were reaching the spermatid stage of development. Some males taken from sea water which had matured previously in fresh water, had fibrous capsules in their testes as remnants of the freshwater lesion but there were no new abnormalities developing in the gonads. The same stock of fish showed other abnormalities and the authors speculate on a possible connection between these changes and the gonad lesion.
Comparative study of the erythrocytes and haemoglobins in nototheniid fishes from Antarctica
Authors: Wells R. M. G. , Ashby M. D. , Duncan S. J. , Macdonald J. A.
Published: January 2006

The blood of seven Antarctic nototheniid species and representatives from three other families contained low haemoglobin concentrations compared with non‐polar marine teleosts. Haematocrit values were slightly lower than values from other teleosts, while haemoglobin and erythrocyte counts were substantially reduced by comparison. Interspecific variation in haemoglobin concentration seemed to be a function of activity level. Mean corpuscular haemoglobin concentration of all Antarctic species was strikingly low by comparison with species from lower latitudes and was not correlated with the habits of the species. Haemoglobin componentry was compared using celluslose‐acetate electrophoresis and, unlike many temperate species, only one major haemoprotein was isolated from each benthic species, but four components were evident in the pelagic species Trematomus borchgrevinki. The possible functional significance of these findings was discussed in relation to the ecology of each species.
The biology of the scaldfish, Arnoglossus laterna (Walbaum) on the west coast of Scotland.
Authors: Gibson R. N. , Ezzi I. A.
Published: January 2006

The biology of a Scottish population of the small bothid flatfish, Arnoglossus laterna, was studied from January 1975 until September 1976. The data were taken from monthly samples totalling over 500 fish trawled in 18–36 m on a soft mud bottom. Otoliths were used for age determination and a growth curve was constructed which showed that most growth occurs in the first 2–3 years of life. The maximum age recorded was 8+ years. The fish first mature sexually in their second year at a standard length of 6–7 cm and the short spawning season lasts from the late June to August. Fecundity is length‐dependent and the relationship could be described by the regression equation: log fecundity = 3·3472 log standard length (mm) ‐2·1064. The diet consists mainly of decapod crustaceans (particularly crangonid shrimps), polychaetes, mysids and small fish.
The ‘Gut index’, a new parameter to measure the gross nutritional state of arctic char, Salvelinus alpinus (L.) and brown trout, Salmo trutta L.
Authors: Jensen Arne Johan
Published: January 2006

The main energy reserves in brown trout, Salmo trutta and Arctic char, Salvelinus alpinus are located in the abdominal cavity and the musculature. The energy content of the rest of the intestines after removal of the gonads, swim bladder, and liver is a good parameter to assess the gross nutritional state of Arctic char and brown trout. This method is laborious, but analysing the dry matter fraction (or the water content) of the same organs instead of their energy content is a practical alternative. The dry matter fraction of these organs expressed as a percentage of its wet weight is here called the ‘Gut index’.
Seasonal changes in the common dab, Limanda limanda (L.) in Isle of Man Waters
Authors: Ortega‐Salas A. A.
Published: January 2006

Otolith accretion was greatest in summer when opaque bands were laid down and slowest in winter when hyaline rings were formed. Food intake was minimal in winter and maximal in summer. Liver weight was high in summer and winter and low in spring after spawning. Growth in length was higher in summer than winter. Gonad weight was greatest in winter for both sexes. Spawning occurred from February to April. After spawning males recovered earlier than females and testes ripened earlier than the ovaries. From winter to summer, the sea temperature increased from 7.5–13.0°C; the day length from 7–17h; and the salinity varied from 34.07−34.36%.
A comparison of five of the methods commonly used to measure protein concentrations in fish sera
Authors: Alexander J. B. , Ingram G. A.
Published: January 2006

The concentration of protein in the sera of rainbow trout, Salmo gairdneri, brown trout S. trutta and Atlantic salmon S. salar has been measured by six standard techniques viz refractometry, copper sulphate specific gravity, automated and manual biuret, optical density and Lowry et al. phenol reagent and the results compared. Good correlation was obtained in most cases and interconversion formulae are given between each method in the three salmonid species. The concentrations obtained with the refractometer and optical density methods were approximately one and a half times those obtained with the others.
The accessory reproductive structure in the simultaneous hermaphrodite Diplectrum bivittatum
Authors: Touart L. W. , Bortone S. A.
Published: January 2006

The general gonad morphology in the simultaneous hermaphrodite, Diplectrum bivittatum from the Gulf of Mexico, agrees with previously published accounts on the gonad morphology of other Diplectrum spp. In D. bivittatum there is a well developed accessory reproductive structure (ARS) which consists of a post‐ovarian sinus and numerous well developed villi which project into the sinus from the sinus wall. The ARS varies seasonally: the post‐ovarian sinus is reduced in February and enlarged during June, September and October when the species is reproductively active. The villi are better developed in September specimens. Two pillar‐like structures within the ARS are described for the first time. Their columnar and smooth muscle cell composition suggests several possible reproductive functions.
Seasonal changes in thyroid hyperplasia, serum thyroid hormone and lipid concentrations, and pituitary gland structure in Lake Ontario coho salmon, Oncorhynchus kisutch Walbaum and a comparison with coho salmon from Lakes Michigan and Erie
Authors: Leatherland J. F. , Sonstegard R. A.
Published: January 2006

A progressive fall in serum thyroid hormone levels was found in Lake Ontario coho salmon, Oncorhynchus kisutch, between May 1978 and January 1979 concomitant with an increase in goitre frequency and thyroid hyperplasia. Despite marked differences in overt goitre frequency in sexually mature adult salmon collected from Lakes Ontario (43.7%), Erie (93.5%), or Michigan (0%), serum thyroid hormone levels and thyroid histology were similar in fish from the three lakes. Two gonadotrop‐like basophil cells (‘globular’and‘vacuolar’) were found in the pituitary, particularly in sexually maturing and mature adults and‘jacks’. Whereas in salmon from Lakes Ontario or Michigan, the globular cells were vacuolated in Lake Erie salmon they were not; this observation may be correlated with the absence of obvious secondary sexual characteristics in Lake Erie salmon. Serum free fatty acids serum, triglycerides and cholesterol concentrations in Lake Ontario salmon fell progressively from the condition in fish collected from the Lake in May 1978, to that of fish collected during their potamodrous migration in November 1978 and January 1979.
Effects of feeding on metabolic rate, and the Specific Dynamic Action in plaice, Pleuronectes platessa L.
Authors: Jobling M. , Davies P. Spencer
Published: January 2006

The rate of oxygen consumption of plaice increases after feeding and declines to a resting level after 24–72 h. The maximum increase corresponds to a level which is approximately twice the resting rate of oxygen consumption. This increase corresponds to the Specific Dynamic Action (SDA) and increases in magnitude with increase in food intake. The magnitude is greatest with high protein content diets. The duration of the SDA effect is reduced with increase in temperature and increases with the percentage of protein in the diet.
Chemical nature of feeding stimulants for the juvenile Dover sole, Solea solea (L.)
Authors: Mackie A. M. , Adron J. W. , Grant P. T.
Published: January 2006

Juvenile Dover sole, Solea solea, were weaned from a live food, Artemia salina nauplii, on to a casein‐based particulate diet flavoured with flesh of the mussel, Mytilus edulis. These fish would not accept an unflavoured casein‐based diet but readily ate the diet flavoured with either mussel flesh or a mixture of pure chemicals whose composition was based on an analysis of the low‐molecular weight fraction of mussel flesh. The rate of growth and survival over a seventy‐seven day period was essentially the same on either of the flavoured diets. The active constituent in the mixture of pure chemicals was identified as glycine betaine for fish of wet weight exceeding 50g while glycine betaine with certain L‐amino‐acids was required for fish of about 2.5 g wet weight. These results are discussed in relation to the known feeding behaviour and food preferences of the wild Dover sole.
Isolation and properties of sarcoplasmic reticulum from the fast muscles of plaice Pleuronectes platessa L.
Authors: McArdle H. J. , Johnston I. A.
Published: January 2006

This paper describes a method for the isolation of highly purified sarcoplasmic reticulum from plaice fast muscle. The interrelationships of pH, KCL, Ca2+, Mg2+, ADP and temperature have been investigated. Protein composition of plaice white muscle sarcoplasmic reticulum was found to be comparable to that described for rabbit fast muscle, with a major component of 100 000 daltons. Arrhenius plots of the Ca2+‐AT Pase are linear over the range 0–30°C. Activation enthalpy (60±1.5 kJ/mol) was found to be independent of KCl concentration. The calcium concentration required to give half maximal activation of the AT Pase (KCa) was found to decrease with increasing temperature, from a maximum of 1.7 μm at 0°C to 0.55 at 20°C.
The involvement of gonadotrophin and sex steroids in the control of reproduction in the parr and adults of Atlantic salmon, Salmo salar L.
Authors: Stuart‐Kregor P. A. C. , Sumpter J. P. , Dodd J. M.
Published: January 2006

Early sexual maturity occurred in the majority of male Atlantic salmon parr. Levels of the plasma androgens testosterone and 11‐ketotestosterone rose steadily as the male parr matured, and decreased as the testes regressed. No such progressive changes were observed in the plasma gonadotrophin (GTH) levels, although the pituitary GTH levels were much higher in mature than in immature male parr; reasons for this, incluiding the possibility that the GTH radioimmunoassay employed is inadequate, are discussed. All female parr remained immature throughout the year, although the gonadosomatic index did show an annual cycle. Adult salmon had higher GTH and sex steroid levels than parr at the same stage of sexual maturity, the levels corresponding to the degree of sexual development of the adult fish.
Some effects of temperature, feeding and body weight on nitrogenous excretion in young plaice Pleuronectes platessa L.
Authors: Jobling M.
Published: January 2006

Ammonium‐nitrogen accounted for 75–85% of the nitrogenous excretion of young plaice, Pleuronectes Platessa L., prior to feeding. Rates of excretion increased with increasing temperature and in proportion to the body weight to the power 0.67. Following feeding the rate of excretion increased to between 2and 11 times the pre‐fed rate and both the peak rate and as the duration of the effect were increased, the greater the amount of nitrogen absorbed from the food. The magnitude of the effect increased with increasing ration and the relationship was best described by an asymptotic equation. Estimates of endogenous nitrogen excretion and maintenance requirements were made from the results of the feeding experiments and were fond to be in close agreement with published data. Estimats of nitrogen requirements obtained from the experiments on fish in the post‐absorptive state yielded values intermediate between endogenous and maintenace requirements.
Feeding and reproductive biology of eleotrid fishes in a tropical estuary
Authors: Nordlie F. G.
Published: January 2006

Five species of eleotrid fishes (Gobiomorus dormitor, Dormitator maculatus, Eleotris amblyopsis, Eleotris pisonis and Leptophilypnus fluviatilis) are known from the Tortuguero estuary of Costa Rica. One, E. amblyopsis, appears tightly linked to the presence of mats of macrophytes and two others, E. pisonis and D. maculatus, are largely limited to this habitat in the lower estuary. All three of these species feed on hyacinth roots. Despite certain food and habitat specializations among the forms, there is evidence of competition and predation among four species. Individuals of breeding size have never been found in the system for D. maculatus and L. fluviatilis. Alternative means of establishing and maintaining eleotrid populations are suggested.
Histopathologic survey of ovaries of fish from petroleum production and control sites in the Gulf of Mexico
Authors: Stott G. G. , McArthur N. H. , Tarpley R. , Jacobs V. , Sis R. F.
Published: January 2006

Ovaries collected from 11 species of demersal and platform‐associated pelagic fishes were examined for petroleum induced lesions. The fish were taken from the north central Gulf of Mexico near 20 oil or gas production platforms and three control sites during two periods, spring and late summer. The status of the ovarian cycle correlated well in the majority of cases with known spawning times. Histopathological conditions most prominent in the ovary other than atresia, generally considered physiological, were acidophilic granular cells, chromatophores and leucocytic foci or infiltration, whereas degeneration, helminths and protozoa with associated tissue responses were rarely noted. Minimal morphological evidence of adverse effects by toxic petroleum elements on the ovary was found., Accepted 21 July 1980
The biology of the common carp, Cyprinus carpio L. in the Camargue, southern France
Authors: Crivelli A. J.
Published: January 2006

Carp were sampled monthly during one and a half years in the Etang du Vaccarès, Camargue, southern France using fyke nets. Densities of carp in temporary marshes and canals were determined using rotenone. Carp is the dominant species in biomass in the fresh and brackish waters (14%0) with densities from 11–58 kg/ha in temporary marshes and up to ten times greater in the canals. Scales were used to determine age and growth of 201 carp. The relative condition factor of female and male mature and unsexed fish are not statistically different throughout the year and follow the variations of gonadal development in spring. The best predictive equation of fecundity, Log F= 7.03504 + 0.83829 log ovary weight, was found using a stepwise multiple regression. The sex‐ratio in the temporary marshes (♂ : ♀; 1.66–1.76) is greater than the general sex‐ratio of the monthly samples (0.67). The diet of carp is characterized by the presence of large numbers of seeds and the absence of large benthic invertebrates. Predation by fish‐eating birds and carnivorous fish is minimal, and the annual drying of many marshes is considered the main mortality factor., Accepted 22 July 1980
The influences of feeding on the metabolic rate of fishes: a short review
Authors: Jobling M.
Published: January 2006

Following feeding, the rate of oxygen consumption of fishes increases to a peak and then slowly declines to the pre‐feeding level. Many factors have been shown to influence the magnitude and duration of post‐prandial oxygen consumption and these include quantity and/or quality of ration and environmental temperature. The effects of the various factors are described and the phenomenon of the post‐prandial increase in metabolic rate of fish is discussed in relation to work with other species of animals.
An ultrasonic biotelemetry system for the continuous monitoring of tail‐beat rate from free‐swimming fish
Authors: Ross L. G. , Watts W. , Young A. H.
Published: January 2006

A telemetry system for the continuous monitoring of tail beats, and hence swimming activity, from loch‐dwelling brown trout, Salmo trutta L., is described. Tail beats are detected by electromyography and are transmitted using a specially‐developed miniature ultrasonic transmitter. The output from the transmitter is relayed to a remote recording station using a radio‐transponder buoy. Data analysed to date show that on average fish are active for only 9% of the time. Tail beat rates rarely exceeded 2.5 tail‐beats per second (TB/s) corresponding to a velocity of 1 body length per second. The fish showed a ‘preferred’ tail‐beat rate of 1.0–2.0 TB/s and consequently they rarely swam at speeds which would incur oxygen debt.
Light and electron microscopic studies on the absorptive cells of the intestine, caeca and rectum of the adult rainbow trout, Salmo gairdneri, Rich
Authors: Ezeasor D. N. , Stokoe W. M.
Published: January 2006

The absorptive cells lining the mucosa of the intestine, caeca and rectum of farm‐reared adult rainbow trout (Salmo gairdneri Rich.) were studied by light and electron microscopy. Most of the intestinal absorptive cells showed morphological characteristics of lipid absorption. The cytoplasm of a few cells was closely packed with mitochondria. The caecal absorptive cells resembled those of the intestine but contained more apical dense bodies and more complex lamellar structures which, in conjunction with the intercellular spaces, appeared to play more active roles in lipid absorption. The rectal lumen was divided into peripheral and central parts by the complex mucosal folds. The surface of the peripheral part was mostly lined by vacuolated cells except for small patches of non–vacuolated (generative) cells between the bases of the folds. The central lumen was lined mainly by a second type of non‐vacuolated cell. The vacuolated cells showed structural indications of a function of absorption of protein macromolecules.

There is morphological evidence to suggest that the pattern of absorption of lipids and proteins in the adult rainbow trout is similar to that demonstrated in stomachless teleosts and that both intraluminal and intracellular digestion of proteins co‐exist in this teleost.
Allozyme evidence for reproductively isolated sympatric populations of brown trout Salmo trutta L. in Lough Melvin, Ireland
Authors: Ferguson A. , Mason F. M.
Published: January 2006

Electrophoretic studies of five polymorphic enzyme loci (G‐3‐PDH‐2, LDH‐I, LDH‐5, PGI‐2, PGI‐3) in brown trout from Lough Melvin in northwestern Ireland have demonstrated that the morphotypes known by the vernacular names of ‘ferox’, ‘gillaroo’ and ‘sonaghen’, are not merely ecophenotypes but represent genetically distinct and reproductively isolated populations. The results suggest that the long life and higher growth potential of ferox trout of this lake, and possibly others, has a genetic basis. These separate demes of brown trout are probably the result of multiple invasions in post‐glacial times of allopatrically derived stocks. Lough Melvin's isolated position and absence of pike, Esox lucius, and large cyprinids have probably contributed to its pristine condition. As such it is one of the few remaining examples of what may once have been a widespread situation in Britain and Ireland.
Thyroid function, pituitary structure and serum lipids in Great Lakes coho salmon, Oncorhynchus kisutch Walbaum, ‘jacks’ compared with sexually immature spring salmon
Authors: Leatherland J. F. , Sonstegard R. A.
Published: January 2006

Whereas spring salmon, Oncorhynchus kisutch, from Lake Ontario had no overt thyroid goiters, comparable Lake Erie spring salmon had a 44% goitre incidence. Goitre incidence in sexually precocious ‘jacks’ from Lakes Ontario and Michigan was 43–45% and 100% in ‘jacks’ from Lake Erie.

All fish displayed thyroid hyperplasia. The degree of hyperplasia (as indicated by thyroid follicle colloid content, thyroid follicle size and shape and thyroid follicle epithelial cell size) in Lake Ontario fish tended to be greater in the ‘jacks’ than in the spring fish; the reverse was true in Lake Erie fish. Serum total L‐thyroxine (T4) concentrations in Lake Ontario spring fish were higher than in any other group. There were no differences in serum T, levels between the groups of ‘jacks’, nor were serum T, levels in ‘jacks’ and spring salmon from Lake Ontario significantly different. Serum total triiodo‐thyronine (T) concentrations in Lake Ontario spring salmon were significantly higher than in all other groups and that in Lake Erie spring salmon greater than in all groups of ‘jacks’. Serum T, levels in Lake Ontario ‘jacks’ were higher than in Lake Erie ‘jacks’. Serum free fatty acid (FFA) and cholesterol levels showed significant interlake differences with lower levels present in Lake Erie salmon. Lake Erie ‘jacks’ appeared to have fewer and less well vacuolated pituitary gonadotropic basophils than ‘jacks’ from Lakes Michigan and Ontario. Putative thyrotrop cells appeared to be more numerous and more active in the Lake Erie spring salmon compared with Lake Ontario spring salmon. Prolactin, corticotrop and melanotrop cells appeared less active in spring salmon than in the ‘jacks’.
Influence of available dietary carbohydrate content on tolerance of waterborne copper by rainbow trout, Salmo gairdneri Richardson*
Authors: Dixon D. G. , Hilton J. W.
Published: January 2006

The effect of increased available dietary carbohydrate on the tolerance of waterborne copper by rainbow trout was investigated. Trout were reared for six to eight weeks on one of four isocaloric and isonitrogenous diets which varied in available carbohydrate content due to either processing (extrusion v. steam‐pelleting) or supplementation with cerelose (0 or 21%). The incipient lethal level (ILL) of copper for trout reared on the low‐available‐carbohydrate steam‐pelleted diet was 350 μg I−1, significantly higher than the 276 μg I−1 shown for trout reared on the high‐available‐carbohydrate extruded diet. The ILL of copper for the low‐carbohydrate group (0% cerelose) was 408 μg I−1, significantly higher than the ILL of 246 μg I−1 of trout reared on the high‐carbohydrate diet (21% cerelose). Increased available dietary carbohydrate resulted in increased liver glycogen content and liver‐body weight ratios and decreased liver protein content. Significant correlations were evident between waterborne copper tolerance and liver glycogen, liver‐body weight ratios and liver protein. Relative to those on high carbohydrate diets, livers of fish on low‐carbohydrate diets contained higher concentrations of copper after seven days of exposure to 0 or 196 μg I−1 of copper. The elevated liver glycogen levels, resulting from increased dietary carbohydrate, are thought to have impaired liver function, thus reducing copper tolerance.
The fine structure of the gastric epithelium of the rainbow trout, Salmo gairdneri, Richardson
Authors: Ezeasor D. N.
Published: January 2006

Fine structural characteristics of the columnar mucus cells lining the surface and pits of the gastric mucosa, oxyntic cells lining the glands and the gastric endocrine cells were studied. The surface mucus cells, in addition to their primary involvement in production of mucus, showed structural adaptations. Release of the mucus vesicles was achieved by exocytosis. Transition from pit gland cells was abrupt since no mucus neck cells were observed. The oxyntic cells possessed apical and basal microvillous processes, a well developed tubulovesicular system, zymogen granules and extensive RER associated with many large mitochondria. When stimulated by distension of the stomach, the apical cytoplasm was converted into a labyrinth of cytoplasmic processes, while annular lamellae, each of which showed a short peripheral linear density appeared in the basal cytoplasm. The endocrine cells showed apical modifications as microvilli, cilia and reduced glycocalyx covering. Three types were distinguished on the basis of their granular morphology.
The blood cells of the Antarctic icefish Chaenocephalus aceratus Lönnberg: light and electron microscopic observations
Authors: Barber D. L. , Mills Westermann J. E. , White M. G.
Published: January 2006

Peripheral blood and haemopoietic tissues of spleen and kidney of the icefish, Chaenocephalus aceratus were examined using LM and EM techniques. The peripheral blood contained cellular elements from all the recognized cell lines usually seen in other teleost groups. Erythrocytes were very rare; when found, they were mature or senile and fragile. Thrombocytes of two morphologies, several cell types considered to be part of the lymphoid series and monocytes/macrophages were present. Two distinctive types of granulocytes also were found; their morphologies and granulation were so different from teleost granulocytes hitherto described that their identification was impossible.
The establishment and subsequent history of a population of Ligula intestinalis in roach Rutilis rutilis (L.)
Authors: Kennedy C. R. , Burrough R. J.
Published: January 2006

The introduction, establishment and subsequent history of a population of Ligula intestinalis in roach, Rutilus rutilus, of a small lake was studied over a period of seven years. The introduction is believed to be a natural, chance colonization achieved by the return of Great Crested Grebes as permanent residents. Within two years the parasite had infected 33% of the roach between 60–120 mm in size. It exhibited a pronounced seasonal cycle in infection. Fish were often infected when only a few months old in autumn, and young fish and parasites over‐wintered together. Parasite growth resumed in the following summer, when some further infections occurred. The majority of infected fish died in or before their second winter, possibly as a result of selective predation, but a small proportion survived into a third year. Dispersion of the parasite was close to random for most of the time. Multiple infections and slight over‐dispersion occurred only in summer months. Infections were scarcer in large fish, due partly to selective mortality of infected fish and partly to a change in the host diet. The pattern of seasonal infection compared favourably with other localities, but prevalence and intensity of infection were consistently lower, parasite dispersion closer to random and multiple infections much scarcer than elsewhere. Infection levels and parasite growth rates varied from year to year, but these annual fluctuations were irregular and showed no consistent pattern. The Ligula population exhibited both regulatory and destabilizing features and there was no definite evidence that it was stable. It is suggested that Ligula is an opportunist species. It is endemic in some sites but in others, especially small lakes, the populations are unregulated and unstable and so persist for short periods only in a non‐equilibrium state.
A preliminary investigation into the vulnerability of young trout (Salmo trutta L.) and Atlantic salmon (S. salar L.) to downstream displacement by high water velocities
Authors: Ottaway E. M. , Clarke A.
Published: January 2006

The downstream movement of young trout and salmon in relation to water velocity was studied in simulated river channels. The results are interpreted as showing that these young salmonids pass through a short period when they are very vulnerable to downstream displacement by flow. Behavioural differences between the two species are considered with the influence on fish movement of changing rate of water velocity, light and temperature.
Effects of salinity on egg development and hatching in grey mullet Mugil cephalus L.
Authors: Lee Cheng‐Sheng , Menu Bruno
Published: January 2006

Grey mullet, Mugil cephalus, collected from ponds were induced to spawn with carp pituitary homogenate and human chorionic gonadotropin (HCG) at 30%o salinity and 26° C. The spontaneously spawned and fertilized eggs were transferred to sea water of different salinities in the range of 5–70%o, either at the 2‐blastomere or the gastrula stage. Those eggs transferred at the gastrula stage were more tolerant to the salinity change than were those transferred at the 2‐blastomere stage. The eggs did develop to the embryonic stage within the salinity range from 5 to 60%o. Hatching occurred in all salinities between 10 and 55%o. However, no larvae survived at 10 or at 55%o. The optimal salinity range for eggs incubating at 22.0–25.5° C was from 30 to 40%o salinity, with the peak at 35%o.
Rainbow trout, Salmo gairdnerii Richardson, spermatozoa: effects of cations and pH on motility
Authors: Baynes S. M. , Scott A. P. , Dawson A. P.
Published: January 2006

Earlier work on the factors influencing inhibition of activation of the spermatozoa of Salmo gairdnerii has been confirmed. Diluents containing K+ and of pH less than 7.8 do not activate the spermatozoa. The presence of Na+ in the diluent has a mildly antagonistic effect on this inhibition. It has now been demonstrated that both Ca2+ and Mg2+ markedly antagonize the inhibition due to low pH and K‐. It is suggested that inhibition due to potassium salts could account for the inhibition previously attributed to Androgamone I.
Osmotic and structural changes during early development of eggs and larvae of the cod, Gadus morhua L.
Authors: Davenport J. , Lønning S. , Kjørsvik E.
Published: January 2006

Newly extruded cod eggs have a similar osmoconcentration (c. 400 mosmol kg‐1) to maternal blood, maternal ovarian fluid and paternal semen. After extrusion, average egg osmolarities rise rapidly to about 520 mosmol kg‐1 but this is entirely due to the cortical reaction resulting in the formation of a perivitelline space filled with fluid isosmotic with the external medium. The ovoplasm remains at around 400 mosmol throughout development; free swimming cod larvae also possess body fluids of this concentration. Over the salinity range 10.2‐37.4%0, salinity had no effect on egg dimensions and average egg osmolarities were consistent with a model assuming changes in perivitellic fluid concentration only.
The effect of the size of Atlantic salmon, Salmo salar L., eggs on embryos and alevins
Authors: Kazakov R. V.
Published: January 2006

A marked diversity in the durations of river and sea existence and the frequency in spawning is shown in the samples of Atlantic salmon females, which were collected over six years. The data are presented on the size and weight of eggs and their dependence on age, and size of females and the time spent at sea. A correlation was established between the size of eggs of embryos and alevins.
The histogenesis of the lymphoid organs in the carp Cyprinus carpio L. and the ontogenetic development of allograft reactivity
Authors: Botham Jane W. , Manning Margaret J.
Published: January 2006

A functional T cell population matures rapidly in the carp, Cyprinus carpio L. At 22 ± 1° C, the thymus first appears at two days post‐hatch and becomes actively lymphopoietic by day 5. The kidney, which contains haemopoietic tissue at day 2, shows differentiating lymphoid cells by day 6–8. The spleen first appears at day 5 but develops more slowly than the kidney.

Lymphocytes are capable of effecting allograft rejection as early as day 16 post‐hatch but the number of cells invading a skin allograft is low if the graft is applied in the first month of life. Thereafter the numbers increase rapidly, possibly correlated with the large increase in lymphocytes in the pronephric and mesonephric kidneys at this time.
Preliminary observations on the heavy metal content of four species of freshwater fish in NW England
Authors: Badsha K. S. , Goldspink C. R.
Published: January 2006

The concentrations of zinc, lead and cadmium in four species of fish from several lacustrine sites were determined. Cyprinids were found to have significantly higher levels of the three metals studied than perch, Perca fluviatilis. Whilst zinc thresholds may be species specific, levels of lead and cadmium vary both within species and sites. There is some evidence that lead and cadmium levels increase with age in roach, Rutilus rutilus. Additionally both cadmium and lead appear to accumulate in the heart, liver, kidney and brain as well as in the bone. Relatively high levels of lead and cadmium were recorded in the eyes of bream, Abrama bramis.
A study of haematological profiles of channel catfish, Ictalurus punctatus (Rafinesque)
Authors: Breazile J. E. , Zinn L. L. , Yauk J. C. , Mass H. J. , Wollscheid J.
Published: January 2006

A blood profile of Ictalurus punctatus was determined from a total of 35 fish. The values obtained included plasma protein, haemoglobin, red cell counts and differential white cell counts.
Effect of a commercial trout diet on liver ultrastructure of fed and fasted yearling coho salmon, Oncorhynchus kisutch Walbaum
Authors: Leatherland J. F.
Published: January 2006

Yearling coho salmon were fed either a commercial trout (TC) diet or a diet consisting of homogenized adult Pacific Ocean coho salmon (PS), supplemented with vitamins and minerals. The hepatosomatic index of the TC‐fed fish killed 12 h after the last feed or after 4 or 8 weeks of fasting were significantly larger (P 0.05) than comparable PS‐fed groups.

‘Light’ and‘dark’ hepatocyte cell types were evident in all groups although the dark cells were less numerous in the fasted fish. Hepatocytes of fasted fish contained markedly more endoplasmic reticulum than fed fish. Hepatocytic glycogen content of the TC‐fed fish was higher than in PS‐fed fish. Whereas in the TC‐fed group hepatic glycogen was still evident in fish fasted for 8 weeks, the hepatocytes of the fasted PS‐fed group contained little or no glycogen. The suitability of commercial fish diets for salmonids is discussed.
Evidence for protogynous hermaphroditism in some lethrinid fishes
Authors: Young P. C. , Martin R. B.
Published: January 2006

An examination of the size/sex relationships and gonadial structure and histology of eight species of the commercially important family Lethrinidae from the North West Shelf of Australia and the Gulf of Carpentaria suggests that protogynous hermaphroditism is the typical mode of sexuality in these fishes. A linear relationship between size and sex ratio, in which females predominate at smaller sizes and males at larger sizes, was demonstrated in five species for which sufficient information was available. All five of these species showed a considerable overlap in the size distribution of the sexes but there was no evidence for the occurrence of primary males in the populations sampled. The tests of all species examined showed typical ‘secondary male’ morphology and the presence of atretic ovarian material (‘brown bodies’). Individuals with intersex gonads were observed in five species. It is suggested that the effects of fishing on such protogynous fish stocks will depend on the precise mechanims, as yet unknown in lethrinids, that control the onset of sex change.
Leucine aminopeptidase activity in the digestive tract of perch, Perca fluviatilis L.
Authors: Hirji K. N. , Courtney W. A. M.
Published: January 2006

The distribution of the enzyme leucine aminopeptidase (LAP, EC 3.4.1.1) in the digestive tract of perch, Perca fluviatilis L., was investigated histochemically. The enzyme was present in the mucosa of the entire intestine and was absent in the oesophagus, stomach and pyloric sphincter. In the intestine, the enzyme was localized in the supranuclear cytoplasm of the columnar cells and was strongest in the brush border area. Enzyme activity was also present in the lumen of the intestine. The activity of the enzyme in the intestine decreased slightly towards the rectum. In perch, the final digestion of peptides and aminopeptides is both extracellular and intracellular and takes place along the entire length of the intestine.
The influence of diet on the digestive enzymes of the Amazon fish Matrinchã, Brycon cf. melanopterus*
Authors: Reimer G.
Published: January 2006

The adaptation of the activity of the digestive enzymes of Brycon cf. melanopterus (Characidae) to diets were studied. The activity of amylase, trypsin and lipase can be increased respectively with a diet rich in carbohydrate, protein, or fat. Pepsin did not show change in activity.
Comparative tolerance to gas supersaturated water of carp, Cyprinus carpio, and black bullhead, Ictalurus melas, from the U.S.A. and Italy
Authors: Gray R. H. , Page T. L. , Saroglia M. G. , Bronzi P.
Published: January 2006

Supersaturation of surface water with atmospheric gases may result from hydroelectric or thermoelectric power generation and adversely affect aquatic biota. Although the phenomenon has been extensively studied in the northwestern United States, its occurrence is less well documented in Europe. We evaluated the tolerance of carp, Cyprinus carpio, and black bullhead, Ictalurus melas, from Italy to gas supersaturated water and compared our results to data reported in the literature for the same species from the Columbia River, U.S.A. Carp and black bullhead from Italy were more susceptible to gas supersaturation than those from the Columbia River. This may reflect greater adaptation of Columbia River fish due to their historical exposure to supersaturated water resulting from numerous hydroelectric dams.
Oxygen consumption of active rainbow trout, Salmo gairdneri Richardson, derived from electromyograms obtained by radiotelemetry
Authors: Weatherley A. H. , Rogers S. C. , Pincock D. G. , Patch J. R.
Published: January 2006

A radiotelemetry apparatus is described for sensing and transmitting electromyograms (EMGs) from free‐swimming fish. EMGs are recorded from the epaxial muscles of adult rainbow trout during periods in spontaneous (= routine) activity, and forced‐swim, respirometers. When such EMG records are integrated, subjected to spectral analysis, and computer‐averaged, the EMG values (in μV) are highly correlated with the fish oxygen consumption during the activity periods. However, there is a marked difference between the regression slopes for oxygen v. EMG value for the data from the spontaneous, and forced‐swim, respirometers; the former slope is the steeper. The probable explanation of this phenomenon is that whereas in forced swims the epaxial myomeres are responsible for most of the activity of the fish, in spontaneous activity other muscle systems (e.g. of the lateral, dorsal and ventral fins) come to account for a greater relative proportion of body movement. The difference in slope, although great, is evidently a regular phenomenon. The shift from one regression to the other occurs at a fairly precise epaxial EMG value (c. 5 μV). This suggests that the laboratory calibration of EMG value in terms of oxygen consumption can be utilized in the wild so that EMG records from free‐swimming fish, fitted with telemetry packages can be used to deduce oxygen consumption attributable to activity. It also appears that such records can be used as a guide to the type of activity of the fish, i.e. desultory movements or free cruising.
The accumulation of copper in Platichthys flesus L. and its effects on plasma electrolyte concentrations
Authors: Stagg R. M. , Shuttleworth T. J.
Published: January 2006

Copper was shown to accumulate in the gills, liver, kidney and plasma of sea water‐adapted and freshwater‐adapted Platichthys flesus exposed to elevated ambient concentrations of the metal. Exposure to sublethal concentrations of copper also caused deviations from control values, of the plasma ions sodium and chloride, indicative of impaired ion regulatory capacity.
A study of some factors affecting rates of oxygen consumption of plaice, Pleuronectes platessa L.
Authors: Jobling M.
Published: January 2006

Oxygen uptake by plaice, Pleuronectes platessa L., was measured using both ‘closed’ and ‘flow‐through’ respirometers. Oxygen consumption was found to be influenced by oxygen concentrations below a critical level of 45–60 mmHg. Rates of oxygen uptake were also affected by fish size, temperature and nutritional status. The problems involved in using values of oxygen consumption, determined in the laboratory, for estimating energy requirements of wild fish are discussed.
A literature review of the blood chemistry of rainbow trout, Salmo gairdneri Rich.
Authors: Hille S.
Published: January 2006

The literature on the blood chemistry of rainbow trout, Salmo gairdneri Rich., is reviewed from the aspects of experimental methods, electrophoresis, normal values, environmental and endogenous factors including toxic substances and diseases.
The dominant fish fauna in the North Sea and its determination
Authors: Jiming Yang
Published: January 2006

The 224 species of fish reported from the North Sea are regarded as being composed of elements of three faunas—Boreal, Lusitanian and Atlantic, and they can be grouped accordingly on both a number of species and a biomass basis. The estimation of biomass of more than 10 important species is based on stock estimates obtained from population data. For 65 non‐standard species the estimate is based on a comparison of catch rates for 'standard’and non‐standard species from groundfish survey data. This involves assumption about the relative catchability of different sets of species. For the other species the biomass are computed in different ways. An analysis of the dominant fish fauna in the North Sea is attempted. The fish fauna in the area is analysed in two ways: by the conventional total number of species from each zoogeographic area, and by the biomass of the representatives of each fauna. It is concluded that for establishing the dominant faunal element of fish, biomass is a better index than is the number of species. The dominant faunal element of fish in the North Sea is Boreal.
Factors affecting the survival of dace, Leuciscus leuciscus (L.), in the early post‐hatching period
Authors: Mills C. A.
Published: January 2006

Young dace fry were stocked into nylon mesh cages at densities ranging from 0·044 to 7·230 1‐1, and the cages anchored in a backwater area where the fry gathered naturally. The fry began feeding on small organisms drifting into the cages 2‐4 days after hatching. The growth rate of the fry was inversely proportional, and the death rate directly proportional, to initial density. Soon after the exhaustion of endogenous food reserves (as determined from unfed fry), there was a period of massive mortality at the highest initial densities, probably due to starvation. After 20 weeks, the cages stocked at the two highest initial densities contained the lowest biomass of fry. Transfer of fry to cages with a larger mesh size produced increased growth and 46% survival over 20 weeks at the lowest initial density. These fry reached an overwintering length of 35·5 mm compared with 48·0 mm for naturally occurring fry.
Histochemical characterization of myotomal muscle in the bluntnose minnow, Pimephales notatus Rafinesque
Authors: Gill H.S. , Weatherley A. H. , Bhesania T.
Published: January 2006

A histochemical study of the axial muscles in the bluntnose minnow, Pimephales notatus Rafinesque, revealed three main types of fibres‐red, white and pink. These were distin‐ guished on the basis of glycogen or lipid contents, or of NADH diaphorase and actomyosin ATPase activities. White muscle formed the largest fraction of the total, whereas red ranged from slightly > 1% of the total cross‐sectional area in the immediately post‐pectoral fin region to slightly <4% in the post‐anal region. Pink muscle formed only a few layers of fibres between red and white. Results are discussed in relation to possible division of labour among the different types of fibres. However, it is emphasized that fibre types may be more functionally versatile in fish muscles than has frequently been supposed.
Aetiology of skeletal deformities in the Zebra Danio fish (Bruchydanio rerio, Hamilton‐Buchanan)
Authors: Newsome C.S. , Piron R. D.
Published: January 2006

Laboratory bred Zebra Danio (Brachydanio rerio, Hamilton‐Buchanan) tropical fish are prone to skeletal deformities resembling scoliosis and lordosis. This condition appears related to diet and has been studied by breeding from different broods of fish for three generations. Two broods bred using two commercially available tropical flaked foods developed severe spinal curvature three to six weeks post‐hatching. A third brood of fish fed exclusively on live food did not develop any deformity. The results demonstrate that a dietary factor is responsible for the deformities and that the Zebra Danio is especially susceptible to this factor as other species breed normally when fed the same commercial diet. Analysis of the diets showed no deficiency in either ascorbic acid (Vitamin C) or tryptophan, deficiency of either being associated with scoliosis and lordosis in fish. The analysis did show, however, a relationship between the lead content of the diet and the incidence of deformities. Lead has previously been implicated in skeletal deformities in second and third generation Brook trout, Salvelinus fontinalis.
Movements and migrations of yellowfin bream, Acanthopagrus australis (Günther), in Moreton Bay, Queensland as determined by tag recoveries
Authors: Pollock B. R.
Published: January 2006

Yellowfin bream were tagged and released in three non‐spawning areas and two spawning areas in Moreton Bay, a large estuarine system on the east coast of Australia. A total of 194 fish were recaptured. Juvenile fish made only small‐scale movements (less than 6 km) from the release site. Small‐scale movements were also recorded for adult fish, although large‐scale movements from 10 to 90 km were also recorded. The large‐scale movements appear to be associated with the migration of adult fish to or from surf bar spawning areas. Some adult fish remained in feeding areas during the spawning season (May‐August). There was no indication from tag recoveries of any movements of yellowfin bream outside Moreton Bay and the results indicate that adult yellowfin bream in Moreton Bay may be regarded as a unit stock for the purpose of fisheries management.
Erythrocyte nuclear measurements of diploid and triploid channel catfish, Ictalurus punctatus (Rafinesque)
Authors: Wolters W. R. , Chrisman C. L. , Libey G. S.
Published: January 2006

Minor axis, major axis, and volume measurements of erythrocyte nuclei were compared by discriminant analysis to determine which variable best predicted ploidy levels. Predicted correct classification percentages for minor axis, volume, major axis, and all variables combined were 81·33, 86·21, 92·36 and 92·65%, respectively. Minor axis and volume measurements were not as accurate in predicting ploidy levels because nuclear shape changed as the ploidy level changed from the diploid to triploid state. Mean major axis measurements alone classified 92·36% of the fish correctly with a discriminant level of 4·726 μm.