bluuebunny/crossref_metadata_2025 huggingface dataset:
Spawning population dynamics of smelt, Osmerus mordax
Authors: Jilek R. , Cassell B. , Peace D. , Garza Y. , Riley L. , Siewart T.
Published: January 2006

A total of 1618 Osmerus mordax were collected between 27 April and 5 May 1977 from five spawning sites along Lake Superior. The fish were measured, sexed, and aged to determine spawning population dynamics. Length/weight ratios of males vs. females varied with males' growth initially concentrated towards length, while females' growth was concentrated toward weight. These growth curves reverse after the third‐year class. Male O. mordax exhibit a higher coefficient of condition.
Induction of antibody‐producing cells in rainbow trout, Salmo gairdneri Richardson; by flush exposure
Authors: Anderson D. P. , Roberson B. S. , Dixon O. W.
Published: January 2006

Splenic antibody‐producing cells were produced by rainbow trout that had been exposed to O‐antigens extracted from Yersinia ruckeri and Aeromonas salmonicida by adding the concentrated antigen preparation directly into the water of the tank holding the fish for a flush exposure. This method was compared with the proven techniques of exposure: intraperitoneal injection or a 2 minute immersion of the fish in the antigen preparation. Dosage experiments showed that the production of antibody‐producing cells was induced by the immersion of trout for 2 minutes in water with 5.0 μg/ml‐1 (or more) with the Y. ruckeri O‐antigen, or 500 μg ml‐1 (or more) of the A. salmonicida O‐antigen. Similar differences were evident when the respective antigens were added directly to the water.
Inbreeding depression in the Zebra fish Brachydanio rerio (Hamilton Buchanan)
Authors: Mrakovčič M. , Haley L. E.
Published: January 2006

Inbreeding depression was observed in Half and Full sib matings (Inbreeding Coefficient 0.125 and 0.25) of Zebra Danios (Brachydanio rerio). Inbreeding at these levels reduced fertility, survival to 30 days, and length at 30 days. There was an increase in the incidence of crippled fry. No effect of inbreeding on either number of eggs per spawn or hatchability were found.
Spontaneous and gonadotropin‐induced ovulation in the goldfish, Carassius auratus L: effects of external factors
Authors: Stagey N. E. , Cook A. F. , Peter R. E.
Published: January 2006

Spontaneous ovulation in goldfish is synchronized with photoperiod and influenced by water temperature and aquatic vegetation. As the latency to ovulation from injection of HCG is highly temperature dependent, the finding that ovulation occurs at approximately the same time of day at temperatures from 12° to 26° C suggests the time of the endogenous preovulatory gonadotropin surge may change with the temperature. The time of spontaneous ovulation adjusts to a reversed light:dark cycle within 2 weeks; some 4–6 h shifts in a single light:dark cycle modify the time of ovulation.

Few sexually mature females kept under long photoperiod (16L:8D) and transferred from cold (13 ± 1°C) to warm (21 ± 1°C) water ovulated spontaneously. Exposure to artificial aquatic vegetation for as little as one light phase significantly increases the proportion offish ovulating in warm water. Fish kept in cold water without vegetation do not ovulate; the addition of vegetation induces ovulation, although the response latency is longer than in warm water. Aquatic vegetation may be an effective stimulus for ovulation in other teleosts which spawn on this substrate.
The adaptation of digestive enzymes to temperature, season and diet in roach Rutilus rutilus L. and rudd Scardinius erythrophthalmus L. Cellulase
Authors: Niederholzer R. , Hofer R.
Published: January 2006

The cellulolytic activity of the contents of the intestinal tract of populations of roach and rudd in four Tyrolean lakes was studied. Much of the activity was taken up with the diet. In fish feeding on plants and detritus a lower cellulolytic activity was found than in fish feeding on zooplankton or on arthropods. A seasonal pattern of cellulolytic activity was demonstrated with a peak in the autumn. It is assumed that the cellulolytic activity found in the intestinal contents of cyprinids is insufficient for the digestion of fibre, but that is suffices—particularly in omnivorous species—to support the breakdown of cell walls.
Progressive changes in haematology and tissue water of sexually mature trout, Salmo gairdneri Richardson during the autumn and winter
Authors: Lane H. C.
Published: January 2006

Rainbow trout of the Kamploops variety were sampled at intervals from October to the end of March. During this period a decline was noted in red cell count, haematocrit, haemoglobin concentration and plasma osmotic concentration. Increases were seen, however, in mean cellular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and the water content of liver and dorsal muscle. Sexual differences were found in all values with the exception of mean corpuscular haemoglobin concentration and the water content of both tissues. Males always had higher values in those parameters in which sexual differences were noted. All trends, with the exception of male haemoglobin and mean cellular volume and female mean cellular volume and osmotic concentration, were significantly linear.

None of the findings in this study could be correlated with temperature or photoperiod. Neither could the declining plasma osmotic concentration be correlated with the rising mean cellular volume or tissue water content. However, correlations were noted between haemoglobin and haematocrit, red cell count and haematocrit and between osmotic concentration and haematocrit. A negative correlation was seen between mean corpuscular haemoglobin concentration and mean cellular volume.
Interspecific dominance amongst three species of coarse fish in Slapton Ley, Devon
Authors: Burrough R. J. , Bregazzi P. R. , Kennedy C. R.
Published: January 2006

Marked changes in the relative numbers of roach Rutilus rulilus (L.), rudd Scardinius erylhroplhalmus (L.) and perch Perca fIuviatilis L., in Slapton Ley, Devon, have been observed over the period 1967–1978. Historically, the lake had been dominated by rudd and perch; significant numbers of roach were not thought to be present until 1967. From then onwards the roach population exhibited a considerable expansion, apparently replacing the rudd, which had virtually disappeared by 1974. In 1975 extensive mortalities of roach were caused by the pseudophyllidean cestode Ligula intestinalis L. During 1976 and 1977 larger number of rudd, belonging to the 1975 and 1976 year classes, were present, suggesting that the roach mortalities might be giving the rudd a chance to recover. However, very few rudd were present during 1978, possibly because lower incidences of ligulosis during 1976–1978 had allowed the roach to recover from the main outbreak of the disease in 1975, and to replace the rudd for the second time. Evidence from trap catches indicated that the perch population had shown a consistent decline between 1970 and 1977. The major phase of this decrease occurred between 1971 and 1973, when the roach population was increasing the most rapidly. Comparisons were made with changes in fish populations in other localities. The major reason for the changes observed was thought to be a competitive relationship between the plankton feeding younger stages, with roach being the dominant species, although other factors may also have been involved.
Haematological assessment of the effects of the anaesthetic MS 222 in natural and neutralized form in three freshwater fish species: intraspecies differences
Authors: Smit G. L. , Hattingh J. , Burger A. P.
Published: January 2006

The effects of different concentrations of natural MS 222 and neutralized MS 222 were studied on the haematology of Cyprinus carpio, Sarotherodon mossambicus and Salmo gairdneri. As judged from the results, MS 222, which is acidic in nature, produced haemo‐concentration effects in all species studied, being least in the trout followed by carp and Sarotherodon mossambicus. These differences are ascribed to acid‐base regulatory functions and metabolic activities of the fish species investigated. The use of neutralized MS 222 improved the haematological profiles markedly and resulted in stabilization of acid‐base parameters and red blood cells sizes and numbers. Haemoconcentration effects, however, still persisted. Trout were found to be more susceptible to the stress of MS 222 anaesthesia than carp and Sarotherodon mossambicus.
Characterization of swimming muscle in the Atlantic mackerel, Scomber scombrus L.
Authors: Gillerman R. G.
Published: January 2006

Both red and white muscle were removed from juvenile and adult Atlantic mackerel, Scomber scombrus L., for histochemical characterization of the muscle fibre types. Staining of white muscle for myosin ATPase, SDH, NADH diaphorase, GPDH and LDH revealed that these fibres are homogeneous. Red muscle was shown to be heterogeneous, of at least two fibre types recognizable on the basis of myosin ATPase staining with preincubation at a pH of 9·8. These two red types are dispersed throughout the red muscle and are present in both juveniles and adults. Red muscle is located both deep within the myotomes and as a superficial layer of muscle fibres. A third group of muscle fibres, intermediate in nature, was distinguished at the apex of the red muscle ‘triangle,’ between the epaxial and hypaxial muscle, using NADH diaphorase and myosin ATPase stains. This paper discusses the possibility that functionally different muscle fibres occur in the red swimming muscle of the Atlantic mackerel.
Endothelial layers in fish skin
Authors: Whitear M. , Mittal A. K. , Lane E. B.
Published: January 2006

Layers of cells limiting the deep face of the dermis and lining the scale pockets can be described as endothelial, using the term in the broad sense. A dermal endothelium has been found in lampreys and in teleosts of diverse form and habits; it consists of a single layer of modified fibrocytes joined by desmosomal and other junctions and having hemidesmosomes and numerous caveolae intracellulares. A fibrous zone interpreted as elastic tissue intervenes between the dermal endothelium and the collagen of the stratum compactum. The scale pocket lining consists of cells with caveolae, desmosomes, hemidesmosomes and usually with basement membrane. The lining may be one or two cells thick and may occur on both aspects of the scale pocket or only on the deeper side, depending on the species. The fine structure of these endothelial layers is compared with that of the vascular and lymphatic endothelia, the scale‐forming cells, the perineurium and the peritoneal lining.
The use of chemical cues in the upstream migration of coho salmon, Oncorhynchus kisutch Walbaum
Authors: Johnsen P. B. , Hasler A. D.
Published: January 2006

The migratory behaviour of coho salmon was studied in the field. Coho salmon, Oncorhynchus kisutch, exposed to synthetic odours in a hatchery and released into Lake Michigan as juveniles, were recaptured as migrating adults 18 months later. The movements of 43 individuals were followed in experiments examining the role of imprinted chemical cues in the homing migration. Movements in relation to controlled distributions of the imprinting odours revealed that chemical cues are used by the salmon in their upstream migration. Acting with the rheotactic response, fish were guided upstream by imprinting odours simulating their home stream. Coho salmon, in the absence of their imprinting odour, respond negatively to the current. Differential responses to current appear to serve in segregating fish imprinted to odours of different home streams.
The biology of pike, Esox lucius L., in a southern eutrophic lake
Authors: Bregazzi P. R. , Kennedy C. R.
Published: January 2006

The biology of pike, Esox lucius L., in a southern productive lowland lake is described. Scales and opercular bones were difficult to read and interpret, and growth estimated had perforce to be based on scale readings. Growth of Slapton pike is average and intermediate between recorded extremes. Both male and female pike reached maximum condition in February, just prior to spawning. The population of pike of over 450 mm fork length in the lake was estimated at 870·6 ± 389·3 in 1975, and 950·4 ± 143.3 in 1976/77. This leads to the conclusion that the pike population has one of the highest biomasses per surface area of water ever recorded. Number of pike per unit area of surface was also high, despite the fact that a significant proportion of the population (fish under 450 mm) could not be adequately sampled. Mean instantaneous mortality rate was 0·53, and mean instantaneous survival rate was 0·59. The roach provided the main item of diet of the pike, with perch taken less readily. Immature pike ate a significant proportion of invertebrates, but roach was again a common feature of the diet of even small fish. Two spawning migrations were identified; at other times of the year, pike were non territorial. The majority of pike spawned in March. Fecundity of a sample of females was assessed. Overall sex ratio was 1:1.
The lateral‐line system of Caspiosoma caspium (Kessler, 1877) and the systematic status of Asra turcomanus Iljin, 1941
Authors: Plnchuk V. I.
Published: January 2006

The lateral‐line system of the Ponto‐Caspian gobiid Caspiosoma caspium (Kessler, 1877) is described, with new data on the arrangement of sensory papillae over the head. The systematic status of related forms, especially Asra turcomanus Iljin, 1941, is briefly discussed.
Metazoan parasites of pike, Esox lucius Linnaeus, from Southern Indian Lake, Manitoba, Canada
Authors: Watson R. A. , Dick T. A.
Published: January 2006

Metazoan parasites of pike Esox lucius from Southern Indian Lake, Manitoba were studied to reveal species composition, differences with host age, sex, and location and season of capture. Pike hosted 18 species of metazoan parasites, two of which, Tetraonchus monenteron and Proteocephalus pinguis, made up over 84% of metazoan parasite numbers. Some parasite species exhibited definite patterns of abundance with host age and season which resulted from changes in host diet and behaviour. No differences in parasite abundance existed between the host sexes. Ranking of parasite abundances was significantly different between two sampling sites only 2 km apart as a result of intermediate host distribution. Impoundment could greatly change pike parasite levels. An initial decrease in parasite numbers could be followed by a rapid increase.
Interactions between vascular actions of detergent and catecholamines in perfused gills of European eel, Anguilla anguilla L. and brown trout, Salmo trutta L.
Authors: Bolis L. , Rankin J. C.
Published: January 2006

Noradrenaline induced vasodilation in isolated perfused eel or trout gills was inhibited by propranolol, aβ‐adrenergic blocking agent. The noradrenaline effect was much reduced in gills of fish which had been kept in 1 mg/l solutions of the detergent LAS (linear alkylate sulphonate; 12C chain length). LAS produced concentration‐dependent vasodilation, which was inhibited by propranolol, in eel and trout gills. Noradrenaline produced additional vasodilation in eel and trout gills which had been dilated by 2.10−8m LAS but had no effect on trout gills perfused with 2.10−7m LAS. Gills from trout which had been kept in 0.1 mg l‐1 LAS responded to noradrenaline normally but the propranolol inhibition appeared to be potentiated.
Carboxymethylcellulase activity in the digestive tracts of fish
Authors: Lindsay G. J. H. , Harris J. E.
Published: January 2006

The digestive tracts of 138 marine, freshwater and farmed fish representing 42 species were assayed for cellulase activity using viscometry. Activity was exhibited by the majority of fish but the level of activity was variable within and between species and was not located in any particular region of the gut. The majority of omnivorous and piscivorous fish demonstrated nil or slight activity, whereas most‘invertivores’† exhibited moderate and high activity levels. This suggests that cellulase activity in fish is the direct result of the ingestion of invertebrates containing cellulase and/or a cellulolytic microflora.
The growth of charr, Salvelinus willughbii Günther, in Windermere
Authors: Frost W. E. , Kipling C.
Published: January 2006

The growth of charr (Salvelinus willughbii Günther) caught in Windermere from 1941–1952 has been studied. Scales were used for determination of age and back‐calculation of length for age. Autumn and spring spawners, males and females, and charr of normal and dwarf growth were treated separately. In fish of normal growth, the spring spawners were significantly smaller than the autumn spawners at ages 1 and 2 years, and significantly larger from age 4 years onwards. There was little difference in growth between males and females within the two spawning populations. Charr of lengths of less than 200 mm at age 4 years were considered to be dwarfs. Mean lengths at capture of male charr were: autumn spawners normal growth 272 mm, dwarf 218 mm; spring spawners normal growth 327 mm, dwarf 194 mm. The oldest recorded age was 8 years.
Recent changes in the fishery of a new tropical man‐made lake, Lake Kamburu (Kenya)
Authors: Dadzie S.
Published: January 2006

Five years after inundation, two varieties of Cyprinus carpio—the common carp and the mirror carp, have appeared in the commercial fishery in Lake Kamburu. Species of Tilapia continue to remain the most abundant fish in the lake and their numbers are on the increase. The second most numerous species is Barbus while Labeo sp. seems to be declining. The numbers of Mormyrus have declined drastically. Species of the genera Tilapia, Barbus and Cyprinus are widely distributed within the lake; Labeo prefers the confluence of the rivers entering into the lake and Mormyrus has moved upriver.
A biological analysis of eel catches, Anguilla anguilla L., from the lagoons of Lesina and Varano, Italy
Authors: Rossi Remigio , Villani Paolo
Published: January 2006

A study of eel catches from Lesina (444 specimens) and Varano lagoons (325 specimens), in southern Adriatic, Italy, was made. Male silver eels in Lesina ranged from 33.4–51.5 cm in length, with a mean of 42.6 cm; from 50–240 g in weight, with a mean of 141 g and were 1.5–6.5 years old with a mean of 2.5 years. The average length of male silver eels in Varano lagoon was 40.5 cm (range 31–48.5 cm); the average weight was 122 g (range 80–220 g)and a mean age of 2.6 years (range 1.5–7.5 years).

The females are bigger, heavier and older than the males with, in Lesina, a mean length of 61 cm (range 50.9–74.3 cm), a mean weight of 438 g (range 240–730 g) and a mean age of 3.4 years (range 1.5–6.5). The average length of Varano female silver eels was 58 cm (range 50.8–72.5 cm), and the average weight was 383 g (range 225–840 g). They were 1.5–7.5 years old, with an average of 3.8 years. Female silver eels were only 20% of the population at Lesina and 10% at Varano.

In comparison with the silver eel populations of the North Adriatic lagoons, the North Sea or the Atlantic Ocean, the silver eels of Lesina and Varano show a greater growth rate, are younger and have a sex ratio in favour of the males.

The water temperature, higher than in other countries, could be an important factor affecting the differences in age and growth rates between Lesina and Varano silver eels and those of other waters.
Fish toxicity and surface tension of non‐ionic surfactants: investigations of antifoam agents
Authors: Müller R.
Published: January 2006

Fish toxicity of etho‐nonylphenol and of two non‐ionic antifoam agents was tested using rainbow trout, Sulmo guirdneri, in 24 h tests. The surface tension of these three compounds was found to depend on concentration and ageing time of the test solutions. The toxicity of the surfactant was about twice as high as known values, with a LC50 of 8.5 mg/1 at 15°C. The addition of antifoam agents to the surfactant solutions further lowered the surface tension but did not alter substantially the fish toxicity of the surfactant. Contrary to expectation, the fish survived in concentrated antifoam solutions at surface tensions as low as 31 dyn/cm for more than 24 h without any apparent damage. The relevance of the surface tension regarding the fish toxicity of detergents in general is critically discussed.
The influence of salinity on oxygen consumption and plasma electrolytes in grass carp, Ctenopharyngodon idella Val.
Authors: Maceina M. J. , Nordlie F. G. , Shireman J. V.
Published: January 2006

Fingerling grass carp, Ctenopharyngodon idella, 90–160 mm t.l., were acclimated to experimental salinities of < 1 (fresh water), 91, 195 and 317 mOsm/kg. Oxygen consumption rates of fish declined, as salinity increased, from 0.16 mg O2/g‐h in fresh water to 0.11 mg O2/g‐h at an ambient concentration of 317 mOsm/kg. Plasma electrolytes (Na+ and Cl−1) and total plasma ionic concentrations increased slightly following 10 days of exposure to ambient salinities greater than 195 mOsm/kg. At 317 mOsm/kg fish appeared to lose control of plasma electrolyte concentrations. As the osmotic gradient was reduced between the fish and the external medium it might have become advantageous to the maintenance of the osmotic equilibrium to reduce blood circulation to the gills, thus imposing a reduction in metabolic rate.
Laboratory observations on the burrowing of the snake blenny, Lumpenus lampretaeformis (Walbaum), in soft sediment
Authors: Nash R. D. M.
Published: January 2006

The Lumpenus lampretaeformis used in this study were caught on soft sediments in Irvine Bay and Ardmucknish Bay (West Coast of Scotland). In aquaria the fish is capable of constructing and maintaining its own burrow in soft sediments. The burrow has a‘Y’configuration which may be made complex by the construction of additional tunnels as the original system begins to decay. The cross sections of these burrows are distinctive in that they have an oval shape in the main tunnel and a rounded cross section in the subsidiary (side) tunnel. Burrowing can be relatively rapid, a burrow with three entrances being constructed within 12 h.
Seasonal patterns in South Africa's Western Cape purseseine fishery
Authors: Crawford R. J. M.
Published: January 2006

Well‐defined, seasonal trends are evident in the availability and distribution of all six contributors to South Africa's Western Cape commercial purse‐seine catch. These are related to spawning, influence the deployment of fishing effort and provide legislating authorities with the prospect of achieving long‐term management objectives through regulation of the open season or the closure of certain areas to fishing.
Sexual differences in the incidence and severity of ectoparasitic infestation of the brown trout, Salmo trutta L.
Authors: Pickering A. D. , Christie P.
Published: January 2006

Hatchery‐reared and wild brown trout, Salmo trutta L., were examined for skin ectoparasites during their spawning period in 1977 and 1978. A total of eight genera of parasites, comprising five ciliates, one flagellate, one monogenean and one parasitic fungus, were identified with as many as five different genera occurring on a single fish. Sexually mature male fish were more frequently or more severely infested by species of Ichthyophthirius, Scyphidia, Gyrodactylus and Saprolegnia than were immature fish of either sex or mature female fish. The differences in ectoparasitic loading could not be correlated with known, seasonal changes in the mucus‐producing potential of the epidermis. These findings are discussed in relation to the defence mechanisms of teleost fish and to some of the endocrinological changes that occur in salmonid fish during the spawning season.
Hyperosmotic infiltration: immunological demonstration of infiltrating bacteria in brown trout, Salmo trutta L.
Authors: Bowers A. , Alexander J. B.
Published: January 2006

Brown trout were subjected to the hyperosmotic infiltration method of bacterial immunization. The route of entry of E. coli into fish was observed by the immunoperoxidase technique on instantly frozen tissue to be through the gills. The passage of bacteria directly into the lateral line system of the fish was not observed.
The effects of splenectomy and subsequent starvation on the storage of haemosiderin by the melano‐macrophages of rainbow trout Salmo gairdneri Richardson
Authors: Agius C.
Published: January 2006

In clinically normal, cachectic and diseased teleost fish, haemosiderin is observed mostly in the melano‐macrophage centres of the spleen and to a much lesser extent in the centres of the kidney and liver. When rainbow trout that had been splenectomised were starved, accumulation of haemosiderin was diverted to the kidney melano‐macrophages.
Gastric emptying in Limanda limanda (L.) and the return of appetite
Authors: Gwyther D. , Grove D. J.
Published: January 2006

Limanda limanda (35–225 g) fed during daytime when trained to use demand feeders under natural photoperiods. Under continuous illumination different feeding rhythms developed which were detected by periodogram analysis. Interfeeding periods (P hours) varied with body weight (W grams) and temperature (T° C) over the range 6.5–15° C as: In P=4.4 – 0.167 (In W) – 0.05 T. Daily food intake (D grams increased with both temperature and size (In D = 0.099 T + 0.579 In W – 3.49). Relative daily intake (R as % body weight, b.w) increased with temperature but decreased with size (In R = 0.099T–0.41 In W + 1.05). These changes in daily intake are primarily caused by changes in feeding frequency; the amount eaten at a meal is relatively constant save at low temperatures (6.5° C) when appetite is suppressed. Dilution of the food with kaolin (from 4.8 to 2.2 kcal/g) did not cause a compensatory increase in meal size or frequency. Gastric emptying time (GET hours) measured by X‐radiography changed with body weight, temperature and relative meal size (M % b.w.) as In GET = 0.68 In M + 0.39 In W – 0.035T + 1.46. With the exception of the lowest temperature (6.5° C) interfeeding periods closely followed GET (P = 1.09 GET – 2.6) supporting the proposal that stomach fullness is a major factor controlling appetite in the dab.
The myoglobin content in red, intermediate and white fibres of the swimming muscle sin three species of shark–a comparative study using high‐performance liquid chromatography
Authors: Kryvi H. , Flatmark T. , Flatmark T. , Totland G. K.
Published: January 2006

A high‐performance liquid chromatographic (HPLC) procedure is described for the determination of myoglobin in extracts of small samples of tissue from the three different fibre types in the swimming muscles of three species of sharks, Etmopterus spinax, Galeus melastomus and Scyliorhinus canicula. The method, which is based on the separation of myoglobin from haemoglobin from haemoglobin based on HPLC using a gel permeation chromatography column, has a detection limit of about 3 pmol myoglobin (Mb). In addition it has the added advantage of specific identification by its Soret band absorption and quantification. In all three species, the three fibre types of the muscle are completely separated and can be isolated at a high degree of purity. In red fibres the myoglobin content varied between 565 nmol mg−1 wet weight (Scyliorhinus) and 170 nmol mg−1 wet weight (Galeus). Intermediate fibres contained from 215 to 57, and white fibres from 11 to zero nmol mg−1 wet weight. The myoglobin content is closely correlated to the vascularization as well as to the amounts of mitochondria in the different fibre types.
Parasites of arctic charr Salvelinus alpinus (Linnaeus) and their use in separating sea‐run and non‐migrating charr
Authors: Dick T. A. , Belosevic M.
Published: January 2006

Metazoan parasites of arctic charr, Salvelinus alpinus, from the Nettilling Lake–Koukdjuak River system, Baffin Island, were studied. Non‐migrating charr hosted 9 species of parasites while sea‐run charr hosted 15 species of parasites. Diphyllobothrium spp., Eubothrium salvelini, and Proteocephalus longicollis were found to be good indicators of non‐migrating charr and Brachyphallus crenatus, Bothrimonus sturionis and Prosorhynchus squamatus were good indicators of sea‐run charr. Using these parasites as biological tags, the proportion of charr caught by the commercial fishery at the outlet of the Koukdjuak River were determined to be approximately 80% sea‐run and 20% non‐migrating charr. Step‐wise discriminant statistical analysis on morphic characters of charr, designated as sea‐run and non‐migrating by their parasites, showed these charr to differ morphologically.
Plasma corticosteroid dynamics in channel catfish, Ictalurus punctatus (Rafinesque), during and after oxygen depletion
Authors: Tomasso J. R. , Davis K. B. , Parker N. C.
Published: January 2006

Plasma corticosteroid concentrations in channel catfish, Ictalurus punctatus, (normally 1.0 ± 0.3 μg/100 ml) increased significantly (to 5.9 ± 1.2μg/100 ml) in response to acute oxygen depletion and then returned to control levels within 30 min after the dissolved oxygen concentration was increased; however, a secondary increase in plasma corticosteroid levels was observed 6 h after exposure. Corticosteroid levels also increased in fish exposed to dissolved oxygen concentration of <0.2 mg/1 for three days. Methylene blue was not effective in preventing interrenal response to low dissolved oxygen. No diurnal plasma corticosteroid rhythm was observed in fish exposed to diurnal chemical rhythms of culture ponds.
A comparison of the activity patterns of the sand goby Pomatoschistus minutus (Pallas) from areas of different tidal range
Authors: Gibson R. N. , Hesthagen I. H.
Published: January 2006

Sand gobies (Pomatoschistus minutus) collected from beaches with a large tidal range (Scotland) exhibit a circatidal rhythm of activity in constant conditions in the laboratory. There is no endogenous circadian component to the rhythm. The phasing of the rhythm is such that peak activity occurs at the predicted time of ebb tide. Light‐dark (LD) cycles applied in the laboratory have a marked effect on activity greatly enhancing it at night so that the original tidal rhythm becomes nocturnal. Some evidence was obtained that LD cycles can entrain a weak nocturnal circadian rhythm in fish removed from tidal conditions. Contrary to expectations, some fish from beaches with a small and unpredictable tidal range (Oslofjord, Norway) also show a weakly persistent circatidal thythm without an endogenous circadian component, but great variability was noticed between individual fish. Laboratory LD cycles did not entrain a persistent circadian rhythm in the fish from the Oslofjord.
Occurrence of Bucephaloides gracilescens metacercariae in three species of gadoid fish
Authors: Johnston B. R. , Halton D. W.
Published: January 2006

Bucephaloides gracilescens metacercaria is a common encysted trematode parasite of whiting, Merlangius merlangus (L), haddock, Melanogrammus aeglefinus (L), and hake, Merluccius merluccius (L), in the Irish Sea. The incidence of infection over an 18‐month period was uniformly high (whiting, 95%; haddock and hake, 100%). The major site of infection in all three hosts was the cranial fluid surrounding the brain. Large numbers of cysts were also found embedded in the spinal nerves posterior to the anus in haddock and hake and in the auditory capsules in whiting and haddock. Other sites of infection included the spinal canal, cranial nerves (V, VII, VIII, X), eye muscles, orbits and nasal region. Results are discussed in the light of previous records of gasterostome trematodes in the Gadidae.
Short term temperature acclimation in myofibrillar ATPase of a stenotherm Salmo gairdneri Richardson and an eurytherm Carassius auratus
Authors: Penney R. K. , Goldspink G.
Published: January 2006

Myofibrillar ATPase activity was measured in the epaxial musculature of rainbow trout acclimated to 5 and 21.°C, and goldfish acclimated to 5 and 30°C. The acclimated goldfish showed considerable differences in the specific activity and thermostability of this enzyme. However, such alterations were not apparent in the acclimated trout. The evolutionary implications of these findings are discussed.
Observations on the structure of brown trout, Salmo trutta Linnaeus, redds
Authors: Ottaway E. M. , Carling P. A. , Clarke A. , Reader N. A.
Published: January 2006

This paper describes the gravel type and structure of brown trout spawning gravels in Teesdale, the flow characteristics of the spawning sites and the size of redds. Factors influencing redd size are investigated and it is concluded that female size is a major factor. Relationships are established between various redd characteristics and the fork length of female fish. The findings are discussed in relation to the existing literature concerning salmonid spawning sites.
Experimental sea ranching of brook trout, Salvelinus fontinalis Mitchill
Authors: Whoriskey F. G. , Naiman R. J. , Montgomery W. Linn
Published: January 2006

An experiment to induce anadromy in a population of wild brook trout, Salvelinus fontinalis, was conducted near Sept‐Iles, Quebec, in 1978–1979. Brook trout were captured from the Matamek River, tagged and transported to the Matamek River estuary during late spring and early summer, and allowed free movement between an impassable waterfall 0.7 km upstream and the sea. Fish were recaptured in autumn as they returned to fresh water. Over two years, 34.0% of the released fish were recaptured. Best returns were in the 2+ and 3+ age classes with 38.0 and 62.1% recaptured, respectively. Straying of transplanted fish appeared to be <1%. All age classes included sea run brook trout (sea trout) but the largest percentages of sea trout occurred in older fish. Growth was better in sea trout than in fish which did not develop anadromy, presumably a function of an increased food supply at sea. Severe tagging effects stunted growth and probably suppressed anadromy, especially among younger fish. Sexual characteristics of recaptured fish indicated suppressed maturation of gonads in sea trout compared to fish remaining in fresh water and there was a shift to a larger percentage of females in the sea trout. Comparisons between our results and data on other anadromous Salvelinus species underscore the potential for sea‐ranching of trout and char as a moderate effort, high yield aquaculture technique.
Effect of sex and size on copper susceptibility of the common guppy, Lebistes reticulatus (Peter)
Authors: Tsai Chu‐fa , Chang Kwei‐yang
Published: January 2006

Multiple regression analyses were conducted to relate rate of toxic action, body weight and concentration for fry, male and female populations of Lebistes reticulatus exposed to copper solutions. For each of these three populations, copper susceptibility decreased as body weight increased. On the basis of the rate of toxic action adjusted with the size factor, the copper susceptibility differed significantly among the fry, male and female populations at the ratios of 2.20:1.55:1.00. When the size factor was not included in calculation, the rate of toxic action or median survival time did not show such a difference between the males and females.
Uptake and distribution of cadmium in the egg of the teleost, Oryzias latipes
Authors: Michibata Hitoshi
Published: January 2006

Eggs of Oryzius latipes in the blastula stage were exposed to M/100 artificial sea water which contained cadmium at the concentrations of 0.1, 1.0, 10.0, 20.0 or 50.0 mg 1−1. The 96 h TL50, value for cadmium was estimated to be 20 5 mg 1−1. When the eggs were incubated for 24 h in the M/100 sea water with 10.0 mg Cd 1−1 and then rinsed in glycine buffer solution (pH; 2.0), the cadmium content of the egg decreased markedly. Cadmium levels were determined in parts of the embryonic body, the chorion and the yolk sac. The most cadmium was detected in the chorion (94.6%). Prolonged cadmium exposure revealed that most of the cadmium was absorbed by the chorion and little was detected in the embryonic body and the yolk sac.
Changes in selected blood component concentrations of rainbow trout, Salmo gairdneri Richardson, exposed to hypoxia or sublethal concentrations of phenol or ammonia
Authors: Swift D. J.
Published: January 2006

Rainbow trout were exposed to sublethal phenol or non‐ionized ammonia concentrations or to hypoxia. Blood samples were taken after various exposure periods and the packed cell volume (PCV) value, the whole blood glucose concentration and the plasma cortisol and chloride ion concentrations measured. At low pollutant concentrations there were no significant changes in the blood components compared to control fish values. At higher concentrations the general response to the stressors was significant increases in the PCV value and the glucose and cortisol concentrations during the first few hours of exposure, followed by a gradual return to normal values in the subsequent exposure time. The increases in glucose and cortisol concentrations were approximately proportional to the pollutant concentrations no such correlation was found for the PCV values. No clear pattern of plasma chloride ion changes was found in any experiment. Levels of no acute effect, in terms of toxic units (TU) based on the pollutants’ 48 h LC50 values, were estimated for phenol as 0.3 TU and for un‐ionized ammonia as 0.1 TU, using the plasma cortisol concentration measurements. The use of fish blood component measurements as general indicators of a stress response is discussed.
Effect of hunger on the daily pattern of feeding rates in juvenile pink salmon, Oncorhynchus gorbuscha Walbaum
Authors: Godin J.‐G. J.
Published: January 2006

Juvenile pink salmon, Oncorhynchus gorbuscha, in two test groups of differing hunger level fed continuously on live copepods, maintained at high densities, throughout 12 h feeding periods in the laboratory. Analysis of video films showed that mean feeding rates were initially (first 10 min) between 51.5 and 63.8 prey‐capture attempts (snaps) fish‐1 10 min‐1, but declined abruptly with increasing satiation to relatively constant levels of about 5.0 and 8.0 snaps fish‐1 10 min‐1, which were maintained during the subsequent 11 h of feeding. The data suggests that after the initial filling of their stomachs with food, juvenile pink salmon keep their stomachs full by feeding at a rate that balances the gastric evacuation rate of 18.6 mg prey h‐1 at 11° C. Less than 15% of the fish's stomach contents need be evacuated apparently for spontaneous feeding to resume or occur. Increased hunger level (by increasing a pre‐test food deprivation period from 24 to 72 h) resulted in fish increasing their average feeding rate and thus their ration consumed from 23.6 to 39.8% dry body weight per 12 h.
The occurrence of Eubothrium fragile (Cestoda: Pseudophyllidae) in twaite shad, Alosa fallax (Lacépède) in the River Severn
Authors: Kennedy C. R.
Published: January 2006

The occurrence, size and maturity changes of Eubothrium fragile have been studied in postlarvae, juveniles and adult twaìte shad, Alosa fallax, from several locations in the River Severn. Parasites were only found in adult shad and not in post‐larvae or juveniles. No juvenile or recently acquired cestodes were identified as such, but adults were present in shad throughout the whole period of their spawning migration. A large proportion of the parasites were gravid upon arrival in the river and, although eggs were subsequently released into fresh water, there was no loss of cestodes from the fish. It was concluded that E. fragile is a marine species, that the parasites found in adult shad in fresh water were the residue of a marine life cycle and that the eggs released in fresh water were part of the parasite's natural reproductive wastage. The distribution and biology of E. fragile were discussed and it is considered that it is typical of the marine species of the genus.
Penetration and distribution of carbon particles in a teleost fish, Poecilia formosa (Girard), the Amazon molly
Authors: Woodhead A. D.
Published: January 2006

The present paper gives data on the tissue distribution of carbon particles in Amazon mollies exposed for periods of 24–120 h to a 0.05% suspension. Very little carbon penetrated the body, either by way of the intestine or the gills. The little amount that entered appeared to pass almost exclusively through the posterior intestine. There was no anatomical specialization of the cells in this area equivalent to Peyer's patches in the intestine of mammals. We suggest that the uptake in the posterior intestine is related to its greater surface area and possibly to some enhanced mobility. After intraperitoneal (ip) injection, carbon that entered the body accumulated at three sites: the heart, the mesentery and, especially, in the head kidney. By 120 h large accumulations were seen in the intertubular areas of the kidney; there was no evidence of excretion of carbon particles from these areas.
Species of Anguilla as indicators of mercury in the coastal rivers and lakes of Victoria, Australia
Authors: Beumer J. P. , Bacher G. J.
Published: January 2006

Mercury concentrations in the axial muscle tissue of most (243) of the 254 Anguilla australis and most (20) of the 27 A. reinhardtii collected from 30 sites in coastal rivers and lakes in Victoria, Australia, during 1975–78 were well below the Australian statutory health limit (0.5 μg g−1 wet weight). For A. australis the mean mercury concentration was 0.17 μg g−1 (±0.16 s.d., range 0.01–1.60 μg g−1); for A. reinhardtii the values were 0.37 ± 0.23 μg g−1 (range 0.12–1.10 μg g−1). Statistical analyses showed that variation in mercury concentration due to total length accounted for only 13% of the total variation in A. australis and 2% in A. reinhardtii whereas locality accounted for 54 and 68%, respectively. Both species are thus considered suitable as indicators of mercury pollution.
Effects of ovariectomy of the dogfish Scyliorhinus canicula L. on circulating levels of androgen and oestradiol and on pituitary gonadotrophin content
Authors: Jenkins N. , Dodd J. M.
Published: January 2006

Levels of androgens and oestradiol in dogfish, Scyliorhinus canicula, plasma, measured by radioimmunoassay, decrease markedly after ovariectomy (OVX). The magnitude and latency of these responses varies according to length of captivity preceding the operation and the time of year at which ovariectomy is performed. Androgens are cleared more rapidly than oestradiol from plasma following OVX, and levels of both steroids are reduced after laparotomy (LAP) in November but not in March. An extract of ventral lobes of the dogfish pituitary induces a significant increase in the circulating androgen levels in LAP fish but not in OVX fish, indicating that the ovary is the major site of androgen production in response to stimulation by dogfish gonadotrophin. Intramuscular injections of oestradiol benzoate (2.5 mg per fish) into LAP fish produce a significant reduction in the gonadotrophin content of the pituitary ventral lobe, measured in the quail testicular cell bioassay, when compared to LAP and unoperated controls. However, no significant changes in the gonadotrophin content of the ventral lobe were seen five days after OVX in June.
Effect of excess vitamin D3 on calcium metabolism in rainbow trout Salmo gairdneri Richardson
Authors: Hilton J. W. , Ferguson H. W.
Published: January 2006

The effect of excess vitamin D3 on calcium metabolism in rainbow trout was investigated. Trout were reared for 24 weeks on diets containing 4000, 104 000 or 1 004 000 iu of supplemental vitamin D3 kg‐1 dry diet. No effect of excess vitamin D3 was detected in the weight gain, feed efficiency or total mortalities of trout in the different groups. None of the fish showed any signs of hypercalcaemia and no significant difference was detected in the calcium, magnesium, phosphorus and sodium content of the trout vertebrae or total carcass. However, there was a significant increase in the calcium, magnesium and phosphorus content of the skin in trout reared on the highest supplemental level of vitamin D3 (1 004 000 iu kg‐1 diet). No overt signs of renal calcinosis were detected in any of the trout. This study indicates that trout are resistant to excess vitamin D3, and that excess vitamin D3 does not appear to be related to the increased incidence of renal calcinosis in rainbow trout.
Copper uptake by two sympatric species of Killifish Fundulus heteroclitus (L.) and F. majalis (Walbaum)
Authors: Bennett R. O. , Dooley J. K.
Published: January 2006

Differential copper uptake within brain, visceral, gill, somatic and residual tissue was examined in the two sympatric species of killifishes Fundulus heteroclitus and F. majalis. Various salinities and copper concentrations were tested on both juvenile and adult stages to examine their effects on copper uptake. Salinity played a significant role in copper uptake in both species of killifishes. However, the effect of salinity was specific for each species and life history stage. Copper content of various tissues was directly related to the uptake pattern exhibited by whole adult fishes. Fundulus majalis brain tissue and F. heteroclitus muscle tissue were exceptions. Severe body lesions and subcutaneous haemorrhaging were observed after 2–3 day exposure to both 2 and 8 ppm copper.
Changes in body musculature with sexual maturation in the European eel, Anguilla anguilla (L.)
Authors: Pankhurst N. W.
Published: January 2006

The structure and distribution of red and white muscles have been investigated in female Anguilla anguilla of varying sexual maturity. Red muscle volumes increased with sexual maturation from approximately 5% of total muscle volume in sexually immature eels to a maximum of 13.3% in sexually maturing animals. Volume increase was due to increasing fibre diameter rather than recruitment of new fibres. Intracellular volume fractions of lipid and mitochondria increased markedly in maturing fish. Artificially matured cels showed the largest increases in muscle lipid. The possible functional roles of red and white muscle during migration are discussed.
The effect of stress on the stomach of the European eel, Anguilla anguilla L.
Authors: Peters G.
Published: January 2006

The gastrointestinal tract is a system that is very sensitive to stress‐like conditions in mammals. Fish display physiological reactions to stress that are fundamentally similar to those of the‘General Adaptation Syndrome’ in higher vertebrates. An investigation was therefore undertaken to determine if morphological changes equivalent to those affecting the stomachs of mammals also occur in fish under stress.

Conflict for social dominance served as the stressor. The unavoidable confrontation with a dominant fish in a tank proved to produce great stress for the subordinate eel. This was demonstrated by a number of physiological and haematological parameters.

Stressed eels have shrunken stomachs, the consistency of which is translucent and soft. The mucous membrane folds flatten or disappear. The mucous epithelium atrophies and during this process numerous residual bodies appear. The cell‐to‐cell contact loosens. The gastric glands degenerate developing large intracellular cavities, vacuolated ER and swollen mitochondria. The connective tissue proliferates replacing the necrotic glands. The submucosal vessels contract, thereby disturbing the circulation.

The consequences of the gastric atrophy (increased self‐digestion, reduction of the immunological barrier, interference with protein digestion, endocrine function, etc.) are discussed.
Infection of the spined loach, Cobitis taenia (L.), by the digenean, Allocreadium transversale (Rud.)
Authors: Robotham P. W. J. , Thomas J. S.
Published: January 2006

The digenean Allocreadium transversale (Rud.) has been recorded once previously in Great Britain. During work on the feeding of Cobitis taenia (L.) it was found to be a frequently occurring gut parasite. Great variation occurred in its seasonal level of incidence and mean worm burden, indicating a rapid turnover and replacement of the parasite in the fish. No significant relationship could be shown between the level of infection and age of the fish; but a highly significant relationship occurred between incidence of infection and fish age.