bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of repeated blood sampling on some blood parameters in freshwater fish
Authors: Hoffmann R. , Lommel R.
Published: January 2006

The effects of repeated weekly blood sampling on blood parameters were studied over a period of 22 days in a salmonid, Salmo gairdneri, and cyprinid fish, Leuciscus idus. The procedure induced mild anaemia demonstrated by decrease of red blood cell counts, haemoglobin and PCV. The changes were more marked in L. idus, which showed signs of increased red cell destruction. No significant trends could be observed in the white blood picture. The results show that blood tests are possible in individual fish, especially S. gairdneri over a long period.
Melanogenesis in normal and phenylthiourea‐treated eggs and larvae of Sarotherodon aureus
Authors: Lanzing W. J. R.
Published: January 2006

The effects of phenylthiourea on the melanophores of eggs and larvae of Sarotherodon aureus were investigated macroscopically and ultrastructurally. Depending on the precise time of application of the drug, partial or total inhibition of melanogenesis of the premelano‐somes was obtained, with total inhibition producing artificial albinos. Coincidentally, phenylthiourea also appeared to suppress somatic growth and development of the fry, presumably due to an additional inhibitory effect on the thyroid gland.
Response of the gill Na+‐K+ ATPase activity, succinic dehydrogenase activity and chloride cells to saltwater adaptation in Atlantic salmon, Salmo salar L., parr and smolt
Authors: Langdon J. S. , Thorpe J. E.
Published: January 2006

Gill succinic dehydrogenase and Na+‐K+ ATPase activities were stimulated by salt water transfer in parr and smolt. Both activities were preferentially located in the chloride cells. Salt water adaptation induced proliferation and enlargement of the chloride cells. Hypertrophy of the chloride cell system occurred in parr adapted to salt water.
Occurrence of stones, sediment and fish scales in stomach contents of demersal fish of the Rockall Trough
Authors: Mauchline J. , Gordon J. D. M.
Published: January 2006

The occurrence of stones, sediment and fish scales was determined among the stomach contents of some 5000 fish. These fish comprised representatives of more than 70 different demersal species, sampled at 250 m bathymetric intervals, from the Rockall Trough, northeastern Atlantic Ocean, at depths ranging from 500 to 2900 m. Stones only occurred in stomachs of fish caught at 500–1000 m depth, their incidence in stomachs with food present being 4.6% at 500m, 1.1% at 750 m and 1.3% at 1000m depth. Sediment occurred in 9%, fish scales in 7%, of stomachs with contents. Sediment and scales co‐occurred in the stomachs of primarily benthopelagic feeding fish. The sediment, however, was associated with the less dominant epibenthic components of the diets while the scales occurred with the more common benthopelagic components. The co‐occurrence of sediment, scales and benthopelagic prey may arise through the former items having longer residence times in the stomachs than, for example, epibenthic prey. There is no evidence of increased occurrence of sediment (and its associated meiofauna) in the diets of fish on the lower slope at depths of 1500–2900 m in the Rockall Trough.
Mark‐recapture experiments on fish in Windermere, 1943–1982
Authors: Kipling C. , Le Cren E. D.
Published: January 2006

Marking experiments on perch, Perca fluviatilis L., pike, Esox lucius L., and charr, Salvelinus alpinus L., have been carried out in Windermere. Numbered tags were used for individual identification, except in some short term experiments on charr. A total of 13 182 perch and 4696 pike were tagged; 2066 charr were tagged subcutaneously and marked with a fin clip. In the short‐term experiments 2015 charr were marked with a fin clip or punched hole. Perch were recaptured up to 8 years after tagging, pike 12 years and charr 5 years. Estimates of numbers and mortality were not satisfactory, except for limited sections of the populations of pike and charr. The main reasons for the unsatisfactory results were: for perch, unknown mortality at time of tagging; for pike, selectivity of the gillnets and in some years low numbers tagged; for charr, restriction to few spawning sites and in some places low numbers recaptured. The experiments provided useful information on movements and growth, which could not have been obtained in any other way.
Relationships between squamation chronology of the bluegill, Lepomis macrochims Rafinesque, and age‐growth methods
Authors: Hudson W. F. , Bulow F. J.
Published: January 2006

Scales first developed on 13 mm juvenile bluegills along the midlateral line anterior to the caudal fin in the area of the caudal peduncle, squamation chronology continued anteriorly, and was completed in the dorsal area of the nape of 25 mm bluegills. Body‐scale relationships calculated from scales taken from three distinct body regions of adult fish were compared using both the Dahl‐Lea and the Fraser‐Lee methods. The calculated body length intercepts followed the chronology of the squamation and compared closely with the observed fish length at scalation of each area. The body length intercepts were different from one another and from the origin. There was little difference among the Dahl‐Lea and Fraser‐Lee calculated lengths beyond annulus one for the three distinct body regions. In all cases, however, results from the Dahl‐Lea method produced lower lengths than their corresponding values calculated by the Fraser‐Lee method. Selected size classes which omitted the smaller fish resulted in body length intercepts higher than those calculated from the total sample regression.
The egg and early life stages of the sandsmelt, Atherina presbyter Cuvier
Authors: Palmer C. J. , Culley M. B.
Published: January 2006

Gravid sandsmelt, Atherina presbyter, were captured from Langstone Harbour, Hampshire, during 1978. They were maintained under laboratory conditions where spawning took place. The egg and its embryonic development are described. From fertilization to hatching took 26–27 days at 15°C and 13–15 days at 20° C. The newly hatched postlarvae were 6.5 to 7.2 mm long. Postlarvae 10.7, 13.4, 15.4 and 19.0 mm taken from the same locality are described and compared with previous descriptions. Their occurrence confirms successful spawning in the central English Channel.
Challenge infections of Gyrodactylus bullatamdis (Monogenea) on guppies, Poecilia reticulata (Peters), following treatment
Authors: Scott M. E. , Robinson M. A.
Published: January 2006

The effects of an initial infection of Gyrodactylus bullatarudis on a challenge infection were investigated using guppies, Poecilia reticulala, by terminating the initial infection after 1 or 2 weeks and immediately reinfecting the fish. Establishment success, mean parasite population size, peak parasite burden, time to peak burden and duration of the infection were all significantly lower in the challenge infections than in the respective initial or control infections. These parameters did not differ significantly between the 1‐ and 2‐week challenge groups.
Histology of cultured channel catfish, Ictalurus punctatus (Rafinesque)
Authors: Soderberg R. W. , McGee M. V. , Boyd C. E.
Published: January 2006

Dissolved oxygen and un‐ionized ammonia concentrations were monitored in 12 0.04 ha earthen ponds stocked with 10 000 channel catfish, Ictalurus punctatus,/ha. Gill, liver and trunk kidney tissue samples were removed periodically for histological examination. Total ammonia and dissolved oxygen levels were in the ranges reported for catfish culture at this level of intensity. Average un‐ionized ammonia nitrogen concentrations ranged from 20 to 67 μgh−1 and average daily maxima ranged from 63 to 183 μgh−1. Gill lesions characteristic of un‐ionized ammonia exposure were common in fish from all ponds.
Temporal and spatial relationships in the movements of loch dwelling brown trout, Salmo trutta L., recorded by ultrasonic tracking for 24 hours
Authors: Tytler P. , Holliday F. G. T.
Published: January 2006

Ultrasonic telemetry was used to record simultaneously, over one complete April day, the movements of four adult brown trout, Salmo trutta, which were residents of a shallow Scottish loch. The daily movements were generally along linear tracks. The home ranges are described as standard and 95% confidence ellipses. The area of standard ellipses ranged from 330 to 633 m2 while 95% confidence ellipses were larger, ranging from 513 to 979 m2. The distances separating individuals, which ranged from 1 to 70 m, were greatest during peaks of activity. Although there was considerable spatial overlap of individual home ranges, the trout were not within visual range for most of the tracking period. Close encounters (proximity <2.5m) occurred most frequently and lasted longest at night. It is concluded, from this study, that brown trout in small productive lochs are solitary but may hold temporary station within widely overlapping home ranges.
Metabolic utilization of body stores during the early life of whitefish, Coregonus lavaretus L.
Authors: Dabrowski K. , Kaushik S. J. , Luquet P.
Published: January 2006

Patterns of oxygen consumption, ammonia and urea excretion were monitored during late embryogenesis, i.e. 5 days before mass hatching and 12 days during the free‐swimming stage of whitefish larvae, Coregonus lavaretus. Oxygen consumption increased from 1.31 to 2.53 mgO2 h−1× 103 eggs−1 at hatching. Fasted, free‐swimming larvae showed increasing oxygen consumption to the tenth day after hatching when it reached 5.52 mgO2h−1× 103 larvae−1. Ammonia and urea excretion increased during pre‐hatching period from 52.1 to 163.2 and 26.8 to 51.4 μgh−1× 103 eggs−1, respectively. The nitrogen excretion rate increased between the sixth and tenth day of fasting, i.e. for ammonia from 117.7 to 160.9 and for urea from 35.8 to 52.5 μg h−1× 103 larvae−1. Cumulative data on nitrogen and energy metabolism indicated that during late embryogenesis, and up to the fifth day after hatching, protein dominated in the energy expenditure. During the free swimming stage, the ratio of fat to protein in energy expenditure rose from 0.86 to 1.99. Combined data for several fish species indicated high dependance of oxygen uptake during the hatching period on egg size and temperature.
Scanning electron microscopy of goldfish, Carassius auratus, intestinal mucosa
Authors: Caceci T.
Published: January 2006

Scanning electron microscopy was used to examine the intestinal bulb and the caudal portion of the intestine proper of the goldfish, Carassius auratus. The observations made correlated well with previous light microscope studies by other investigators. The mucosal surface of the entire intestine of the goldfish is thrown up into folds, which are oriented along the long axis of the digestive tract in the intestinal bulb, but run more or less transversely in the caudal intestine. Tops of the folds were observed to be rounded or flattened, and the folds themselves formed wavy or zigzagging patterns in the mucosal surface. Numerous mucus‐secreting goblet cells were seen, which were apparently more numerous or more active in the caudal intestine than in the intestinal bulb. The goblet cells are not uniformly distributed throughout the mucosa: they are more evident on the sides of the folds, although occasionally they appear to be located in clusters on the tips.

The goblet cells were observed to contain varying amounts of mucous material, and/or to be of different sizes. Although no histochemical tests were performed, the possibility that digestive enzymes known to be present in the intestine may be elaborated by the goblet cells was considered, based on their variable appearance.
Growth and mortality of zebra fish, Brachydanio rerio (Hamilton Buchanan), maintained at two temperatures and on two diets
Authors: Craig J. F. , Fletcher J. M.
Published: January 2006

One hundred zebra fish per tank were maintained for 112 days at 24°C or 28°C in glass aquaria and fed a diet of flaked food made without cellulose (13.45 kJ g−1, metabolizable energy, Type A) or with cellulose (8.71 kJ g−1, metabolizable energy, Type B). Each experimental condition was repeated in triplicate (12 tanks). The weight of food given daily to the fish was based on daily records of survivors (from which mortality rates were calculated) and wet wt of fish (measured every 14 days) in each tank. All fish were fed with the same weight of food per day and the quantity of energy in the food in excess of standard metabolism (as a proportion of SM) was approximately 0–5 for fish maintained at 28°C and fed food B, 1–0 for fish maintained at 24°C and fed food B, 1–5 for fish maintained at 28°C and fed food A, and 2.2 for fish maintained at 24°C and fed food A.

Non‐ionized ammonia, nitrite and nitrate nitrogen in the tanks did not reach toxic levels although there was an increase in total ammonium nitrogen in one tank and a subsequent heavy mortality. It was assumed that this was caused by the build up of pathogenic bacteria. Apart from this tank, mortality was highest in tanks at 28°C with fish fed food A and second highest in tanks at 24°C with fish fed on the same diet. Growth was measured in units of length, wet and dry weights, carbon and energy. There was a good correlation (P < 0.001) between carbon (mgC mg−1) and calorific (J mg−1) values and a conversion factor of 46.2 J (mgC)−1 was derived. Fish maintained at 24°C and fed food A had the highest rates of growth both in weight and in energy value per unit weight. Fish fed the same diet but kept at 28°C had the lowest growth rates. Both these groups of fish had the highest coefficients of variation in wet weights which increased during the experiment, indicating an increase in interaction within the tanks. There was agreement between the energy value of fish sampled for growth and a condition factor based on the length‐weight relationships of fish remaining in the tanks. A correlation (P < 0.05) was found between instantaneous mortality and growth rates for fish between tanks when those maintained at 28°C and fed on food A were ignored.
Versatility in habitat use by a top aquatic predator, Esox lucius L.
Authors: Chapman C. A. , Mackay W. C.
Published: January 2006

The habitat selected by northern pike, Esox lucius, a solitary top aquatic predator, was evaluated using radio location and ultrasonic telemetry. These predators moved extensively throughout the lake and exhibited a distinct preference for shallow vegetated areas close to shore. Selection of habitat was significantly influenced by meteorological factors. On windy days pike chose habitats which were further from shore, but not necessarily deeper, than those chosen on calm days. On sunny days pike moved into habitats that were close to shore and relatively shallow. Habitat selection of pike was not significantly influenced by rain. Northern pike exhibited a much greater versatility in the range of habitats they utilized than was previously believed. We propose that such versatility is an important feature of the behaviour of top predators.
Salinity tolerance of young catfish, Clarias lazera (Burchell)
Authors: Chervinski J.
Published: January 2006

Experiments were conducted to determine the adaptability of young catfish, Claria lazera, to various saline concentrations. Young catfish, total length 52–88 mm, were subjected to abrupt and gradual changes from fresh water (salinity = 0.14‰) to various salinities. Ninetyfour per cent survival occurred when the fish were transferred from fresh water to 25% sea water (salinity = 9.5‰ No fish survived higher salinities even through gradual change.
The influence of light environment on depth of visual feeding by larvae and fry of Coregonus pollan (Thompson) in Lough Neagh
Authors: Dabrowski K. R. , Jewson D. H.
Published: January 2006

The depth limits for visual feeding by pollan larvae and fry, Coregonus pollan, were determined in Lough Neagh, Northern Ireland, by combining laboratory estimates of the minimum light threshold for feeding activity with field measurements of spectral, diurnal and seasonal changes in light penetration. Although feeding thresholds were lowest in the blue light (400–490 nm), the rapid attenuation of this region in the lake meant that the depth limits of feeding in situ were determined by response to the green region (490–595 nm). Effects of changes in irradiance and light penetration on the depth of feeding are considered during a seasonal study. Increased sensitivity, as the juvenile stages develop, may be offset by reduced light penetration due to algal growth. Over an annual period the maximum feeding depth for pollan varied between 2.6 and 4.1 m. In the juvenile stages of two other predatory species from the lake, perch, Perca fluviatilis, and pike, Esox lucius, the corresponding ranges were 1.1–1.9 m and 2.7–4.6 m respectively.
The effect of seasonal changes on the activity of intestinal alkaline phosphatase of pike perch, Lucioperka lucioperka and of bream, Abramis brama
Authors: Gelman A. , Mokady S. , Cogan U.
Published: January 2006

The effect of seasonal changes on the activity of intestinal alkaline phosphatase was evaluated in two types of fish grown in the Kurshskii bay of the Baltic sea. With the pike perch, Lucioperka lucioperka, higher enzyme activity and optimal temperature of activity were observed in the summer compared to winter, whereas with the bream, Abramis brama, essentially no difference in enzyme activity and in optimal temperature of activity was found between the two seasons. In both fish, the thermal stability of the enzyme and the activation energy of enzyme activity decreased in winter. The different biological nature of the two fish appears to be reflected in the response of the intestinal alkaline phosphatase to seasonal changes.
Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo
Authors: Watson D. J. , Balon E. K.
Published: January 2006

Average species richness for fish taxocenes in the Nida River (Poland), Grand River (Ontario) and Baram River (Sarawak, Malaysia) was 7, 16 and 24 species respectively. Discriminant analysis of 15 morphological attributes indicated Baram fishes partitioned the habitat vertically into mainly surface, pelagic, benthic and substratum niche types. Attribute comparisons among the river systems revealed a progression towards more sedentary benthic morphologies with increasing average species richness. Similarly, niche compression as a consequence of increasing average species richness was indicated by a reduction in length of life and average size, and was associated with development of complex life‐history and reproductive styles. Total niche space occupied by the fish taxocenes was comparable in the three river systems despite differences in species richness. The amount of species packing and niche space occupied by Baram fish taxocenes were also not related to the numbers of species present. Fish community structure was apparently determined by the range of available resources and the associated specializations of the coexisting species.
Weight loss and change of condition factor during fixation of Pacific herring, Clupea harengus pallasi, eggs and larvae
Authors: Hay D. E.
Published: January 2006

Dry weights of unfixed eggs and larvae of Pacific herring, Clupea harengus pallasi, taken at six different periods during development, were compared to those of larvae stored for 10 days in fixatives varying in salinity (0, 15, 28%‰) and formalin (4, 10, 20%) concentration. In most instances there was some weight loss of the fixed specimens. In general weight loss varied inversely with salinity and formalin concentration and was greater in larvae than eggs. Weight loss was greatest in recently fertilized eggs and decreased in older eggs. Weight loss in recently hatched larvae varied from 19 to 36% depending upon the salinity and formalin concentration. Weight loss varied inversely with larval size and fixation increased weight in some large larvae. Weight change during fixation could result in an artificial inflation of the estimate of condition factors, particularly in the younger smallest larvae.
Emptying rates of single and double meals of different food quality from the stomach of the dab, Limanda limanda (L.)
Authors: Fletcher D. J. , Grove D. J. , Basimi R. A. , Ghaddaf A.
Published: January 2006

In previous studies on gastric emptying time in Limanda, data were obtained which predict that food will empty from the stomach according to:

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after a temperature sensitive delay. This curve gives an excellent prediction of the emptying of both artificial and natural food items given as single meals when stomachs are sampled directly. However, when two meals are given 3 h apart, emptying rate depends on whether the two meals remain separate or are allowed to mix by omitting the binding agent. In the absence of a binder, both meals are slowed so that the overall emptying rate is as predicted by the equation. When binder is present, the first meal is not delayed and the overall gastric emptying rate is increased 35%.
Protein, lipid and caloric contents of bluntnose minnow, Pimephales notatus Rafinesque, during growth at different temperatures
Authors: Gill H. S. , Weatherley A. H.
Published: January 2006

Changes in the relative proportions of protein, lipid, water and caloric contents of bluntnose minnow growing at various temperatures (15, 25, 30° C) were investigated by application of the allometry equation, y=axb. Fish grew significantly faster at 25° C (closest to optimum), more slowly at 30° C and most slowly at 15° C. Protein, as a percentage of body wet weight, tended to increase with fish size at all temperatures (b > 1.000), whereas in juveniles (<0.7 g) it decreased (b < 1.000). However, with the exception of the 15° C group, protein as a percentage of body dry weight, decreased in all groups (b < 1.000). Temperature appeared to modify the body composition of bluntnose minnows, e.g. decreasing temperature led to significantly enhanced protein content during growth. Lipid (%) and caloric content (cal g−1) increased with increasing fish weight (b > 1). The slower growing fish (15°, 30° C) deposited significantly more lipid (and had higher caloric contents) than those growing most rapidly (at 25° C). Water content (%) decreased with increasing body weight in all groups. Despite intergroup growth rate differences, all groups showed evidence of a tendency to follow similar trends in b values for body constituents and caloric content (except for protein v. body dry weight for the 15° C group). This suggests a general conservativeness of body composition in bluntnose minnow. The correlations between body constituents, caloric content and body weight were high (r2>0.9) so that estimates of body composition can be obtained from body weight for all temperature groups.
The reproductive biology and estuarine movements of the gizzard shad, Nematalosa vlaminghi (Munro)
Authors: Chubb C. F. , Potter I. C.
Published: January 2006

The microscopic development of the egg of the Perth herring, Nematalosa vlaminghi, has been related to the gross changes observed in the ovary. The patterns of change in the diameter of the oocyte, oocyte nucleus, yolk vesicles and yolk granules and the thickness of the theca, granulosa and zona radiata have been quantified. Three modes were present in frequency histograms of the diameter of oocytes in sexually‐mature females, two of which corresponded to opaque and hyaline yolked‐oocytes. The mean number of hyaline oocytes was 20430, which represented 35% of the mean number of all yolked oocytes (57610). Seasonal trends in gonadosomatic indices, together with the changes in the macroscopic and microscopic condition of the ovaries, demonstrated that spawning activity reached a peak in December‐January. The place of capture of mature animals and 0+ recruits showed that breeding occurred near the top end of the upper estuary. During the ensuing weeks, the young fish dispersed throughout the upper and middle estuary while the older fish moved out to sea.
Effects of pre‐ and post‐prandial starvation on meal size and evacuation rate of juvenile Atlantic salmon, Salmo salar L.
Authors: Talbot C. , Higgins P. J. , Shanks A. M.
Published: January 2006

After a pre‐prandial period of starvation or feeding with unlabelled food, 0+ salmon parr (0.8–11.7 g) were fed a test meal of iron particle labelled food and subsequently were again either starved or fed unlabelled food. The quantity of labelled food consumed and the evacuation rate was determined by serial radiographs. In fish of all sizes, pre‐prandial starvation causes a larger test meal (as a percentage of body weight) to be consumed when compared to pre‐prandially fed fish. In addition, pre‐prandial starvation results in relatively larger meals as a percentage of body weight being taken by smaller compared to larger fish. This result was not evident for pre‐prandially fed fish. Evacuation rate was unrelated to body size irrespective of feeding history. Post‐prandial starvation decreased evacuation rate but this effect was inversely related to the quantity of food consumed. Larger meals were not evacuated differently from smaller meals if feeding occurred post‐prandially, irrespective of pre‐prandial starvation.
The effects of increasing shoal size on handling time in goldfish, Carassius auratus L.
Authors: Street N. E. , Magurran A. E. , Pitcher T. J.
Published: January 2006

It is a general assumption that handling time is a constant, given an unvarying size relationship between predator and prey, and an unchanging hunger level. These results indicate that handling times for a pellet of food shown by individual members of a shoal of goldfish decrease by some 20% as the number of fish in the shoal increases from two to 15. Two mechanisms for this reduction are suggested, both of which could act simultaneously. First, there is greater competition for available food resources in a larger shoal and, second, the reduced need for vigilance in a larger shoal will enable individuals to devote more effort to the handling of their food.
The dynamics of a declining population of the acanthocephalan Acanthocephalus clavula in eels Anguilla anguilla in a small river
Authors: Kennedy C. R.
Published: January 2006

Changes in the size and composition of a population of the acanthocephalan Acanthocephalus clavula in eels, Anguilla anguilla, and flounders, Platichthys flesus, its definitive hosts, in a small river are described over a period of 4.5 years in the course of which the population underwent a steady and continuous decline. Parasite prevalence and abundance declined more rapidly initially and then more gradually, and during the period the frequency distribution changed from overdispersed to being close to random on most occasions. Throughout the whole period newly recruited parasites were found in eels, and adult females continued to mature and produce acanthors. Data on the distribution and occurrence of the intermediate host Asellus meridianus in the river suggested that in the latter part of the decline it was no longer possible for the parasite to complete its life cycle in some parts of the river, and the cause of the parasite population decline is believed to be the decrease in abundance of the intermediate host as a result of interspecific competition with a congeneric species. During this latter period, immigration of infected eels from another river in the catchment may have contributed to the maintenance of the parasites in the locality, but it is considered that the decline in the river was representative of what was happening in other parts of the catchment and that the whole parasite population in the catchment was declining for the same reason.
Agglutination of spermatozoa by autoantibodies in the rainbow trout, Salmo gairdneri
Authors: Secombes C. J. , Lewis A. E. , Laird L. M. , Needham E. A. , Priede I. G.
Published: January 2006

Agglutinating antibodies to self spermatozoa were induced in mature male rainbow trout, whether immunised with autologous spermatozoa or allogeneic testis. Both sperm heads and flagellae appeared to be autoantigenic. These are the first results which show that fish can produce autoantibodies against spermatozoa. This is an important step towards the control of reproduction in fish using vaccines.
An automated ultrasonic telemetry system for the assessment of locomotor activity in free‐ranging rainbow trout, Salmo gairdneri, Richardson
Authors: Rogers S. C. , Church D. W. , Weatherley A. H. , Pincock D. G.
Published: January 2006

A new automated ultrasonic telemetry system for monitoring the swimming activity of adult rainbow trout, Salmo gairdneri, at liberty in the wild is described. The transmitter detects bioelectric potentials (i.e. electromyograms) associated with the contraction of the epaxial myomeres during swimming. Transmitter output is relayed to the signal processing system via submerged hydrophones. The incoming signals represent averaged electromyograms which have been shown in earlier studies to correlate well with swimming activity and concurrent oxygen consumption of rainbow trout in the laboratory.

Electromyogram records obtained from rainbow trout released into a small lake and monitored for up to 4 weeks, indicate a fairly regular pattern of elevated midday activity contrasting with periods of relative quiescence during the evening and morning. This midday peak in locomotory activity is the result of an increased feeding activity which is evidently a response to a concomitant increase in the activity of the fish's prey.
The biology of the black goby, Gobius niger L. in an English south‐coast bay
Authors: Vesey G. , Langford T. E.
Published: January 2006

A population of Gobius niger in a south‐coast bay was sampled over a 12‐month period. The bay received the cooling water discharge from Fawley power station. Four year‐classes were recorded of which the 1+ group was found to be responsible for the bulk of egg production. The main spawning period was from April to May although some evidence of batch spawning was found. Growth was found to be faster than has been reported for populations elsewhere, possibly because of the raised water temperature. Despite higher temperatures the growing season was not extended beyond that of other comparable black goby populations, being restricted to a 4–5 months period after the main spawning period. Seasonal changes in diet were believed to be the result of the effect of water temperature on fish movement. Feeding occurred throughout the year.
Comparison of the surface properties of seven strains of a fish pathogen, Aeromonas salmonicida
Authors: Johnson C. M. , Tatner M. F. , Horne M. T.
Published: January 2006

Several physical properties related to the surface characteristics of autoaggregating and non‐autoaggregating strains of Aeromonas salmonicida have been investigated. Properties examined included resistance to the bactericidal action of trout serum, adhesion to fish leucocytes and fish cell monolayers in vitro, resistance to phagocytosis by fish leucocytes and the in vivo localization following intraperitoneal injection. For each strain the presence or absence of an extracellular protein A‐layer was investigated and the pathogenicity for brook trout determined.

Presumptive A‐layer protein, in the form of a 49 kdal subunit, could be detected only in one of the strains examined. This strain autoaggregated and was the most resistant to serum bactericidal activity. Complement activation by the alternative pathway was thought to be responsible for this heat‐labile bactericidal activity. Three strains that autoaggregated and three that did not had no detectable A‐layer. Autoaggregating strains appeared more adhesive to both fish cell types but all strains were phagocytosed by fish leucocytes to a similar degree. An autoaggregating strain was localized in the spleen. The seven strains were only moderately pathogenic for brook trout, possibly as a result of the challenge system. In view of this, no property investigated could be correlated with greatly increased virulence.
An in situ estimate of daily food consumption and alimentary canal evacuation rates of common carp, Cyprinus carpio L.
Authors: Garcia L. M. , Adelman I. R.
Published: January 2006

Daily food consumption and alimentary canal evacuation rates for common carp, Cyprinus carpio L., were estimated at 4‐week intervals from April to October 1979. Both the rate of food evacuation and its relationship to temperature were described by an exponential function. Gut evacuation rates ranged from 6.0% of gut contents per hour at 9°C to 32.7% h−1 at 26.5°C. Temperature accounted for 72–91% of the variation in gut evacuation rate among months. Daily food consumption varied from a low of 3.87 mg g−1 of fish wet wt per day in April at 14°C (0.39% of wet body wt) to a high of 40.75 mg g−1 (4.08%) in August at 26.5°C. Although a greater quantity of food appeared to be consumed during the morning in spring and early summer and a greater amount in the evening after July, there was not a statistically significant time of day for peak feeding activity. The field method described here seemed to provide reasonable estimates of food consumption compared with other field and laboratory studies.
Behavioural responses of fishes to chemical cues: results from a new bioassay
Authors: Jones K. A. , Hara T. J.
Published: January 2006

A new behavioural bioassay for determining the locomotor response by fish to chemical cues is described. The assay combines a behavioural trough, capable of delivering up to 10 discrete plumes of treated water, together with a digital method for quantifying the movements of single fish. Sample responses of two whitefish, Coregonus clupeaformis, one to an attractant (a food extract) and one to a repellant (quinine monohydrochloride), are provided. Their locomotor responses are analyzed in terms of such parameters as total distance travelled, average velocity, number of turns, average excursion distance, and the number of times specific boundaries are crossed. The assay's sensitivity is demonstrated through concentration‐response curves by Arctic char, Salvelinus alpinus, to the bile acid, taurocholic acid, and the amino acids, L‐serine and L‐alanine. Behavioural response threshold concentrations for these three substances were estimated to be 10−15, 10−n, and 10−9 m, respectively.
Histological changes in the gill, kidney and liver of Lahontan cutthroat trout, Salmo clarki henshawi, living in lakes of different salinity‐alkalinity
Authors: Galat D. L. , Post G. , Keefe T. J. , Bouck G. R.
Published: January 2006

Lahontan cutthroat trout thrive in saline‐alkaline lakes, where other trout species often cannot survive. We examined Lahontan cutthroat trout from nine lakes in which salinity and alkalinity ranged from about 90 to 12 000 mg1−1 and 60 to 3500mgl−1 as HCO3− respectively, for sublethal histological changes in gill, kidney, and liver tissues. Gill chloride cell hyperplasia, gill lamellar epithelial separation, kidney glomerular swelling, blood congestion in kidneys, and deposition of hyalin droplets in kidney glomeruli, tubules, and hemopoietic tissues were the histological alterations statistically associated with differences in lakewater chemistry.

Deposition of hyalin in kidney tubules was the only histological change judged pathological and whose severity appeared sufficient to jeopardize normal organ function. Differences in lakewater chemistry explained nearly 90% of the variability observed in severity of tubular hyalin degeneration, and SO42− was the ion most positively correlated with increasing tubular hyalin. Our results suggest that Lahontan cutthroat trout will develop slight to moderate hyalin degeneration in kidney tubules if stocked into lakes where salinity and SO42− concentrations equal or exceed 5000 mgl−1 and 2000mgl−1, respectively.
Effects of steroid hormones and other substances on alarm substance cells and mucous cells in the epidermis of the European minnow, Phoxinus phoxinus (L.), and other Ostariophysi (Pisces)
Authors: Pfeiffer W. , Walz U. , Wolf R. , Mangold‐Wernado U.
Published: January 2006

The alarm substance cells and mucous cells of various species of Ostariophysi do not react uniformly to treatment with androgen and other steroid hormones. This indicates that the mechanism controlling formation of alarm substance is not uniform in the Ostariophysi and three exist at least two such mechanisms, one of which is operated by androgens and perhaps other steroid hormones of the gonads. Steroid hormones from the adrenal cortex proved ineffective. In the European minnow, anti‐androgen (androcur®, cyproteroneacetate) had an efrect opposite to that of androgen, while androgen treatment upon this species led to an increase in the size of mucous cells and a reduction in the alarm substance cells. The epidermis of androgen‐treated European minnows contained neither alarm substance cells nor alarm substance, and skin extracts of such fish proved ineffective in behaviour experiments upon fish schools. The effect of further hormone treatments are discussed and the reactions of the European minnow are compared to those of other species.
Effect of rearing density on thyroid and interrenal gland activity and plasma and hepatic metabolite levels in rainbow trout, Salmo gairdneri Richardson
Authors: Leatherland J. F. , Cho C. Y.
Published: January 2006

There were significant inverse correlations between rearing density of rainbow trout, Salmo gairdneri Richardson, and final body weight, plasma L‐thyroxine (T4), trüodo‐L‐tryronine (T3), cortisol and protein concentrations, plasma T4/T3 ratios and thyroid epithelial cell height. In addition, hepatosomatic indices and plasma free fatty acid concentrations were higher in fish reared at low (134 g 1−1) density compared with groups reared at medium (210g1−1) or high density (299g 1−1), and the post‐feeding (3.5‐4h) elevation in plasma glucose and triglyceride levels evident in trout maintained at low rearing density was not found in those fish reared at higher densities. There were no significant effects of rearing density on hematocrit, carcass composition, hepatic glycogen and lipid levels and interregnal nucleus size.
Aspects of the mating behaviour of male mollies (Poecilia spp.)
Authors: Woodhead A. D. , Armstrong N.
Published: January 2006

The unisexual fish Poecilia formosa (the Amazon molly) reproduces by gynogenesis, a process in which sperm from the males of the host bisexual species activates development of its eggs. Unisexuals live with one of the host species in nature and compete with bisexual females for the males. It was long thought that male discrimination and mate selection established a balance between the unisexual and bisexual populations. Thus, hierarchies of males were set up in which dominant males mated with their conspecific females and subordinates mated with the Amazon molly. Recent evidence suggested, however, that male fish do not discriminate between their own females and the Amazon molly, and that there always are more males available than sexually receptive females of both species.

Our findings indicate that male behaviour may be more complex than suggested by either hypothesis. Mate discrimination and courtship behaviour appear to increase with age, so that large males show almost complete preference for their conspecific females, but smaller males will mate with the Amazon molly. In complex groups, small males often dart in and mate with their own females whilst the large males are engaged in courtship activities and defence of territory.
Latent behavioural toxicity of copper to sea catfish, Arius felis, and sheepshead, Archosargus probatocephalus
Authors: Steele C. W.
Published: January 2006

To assess quantitatively the latent (delayed) toxicity of acutely sublethal exposure to copper on the locomotor and orientation behaviour of marine teleosts, the movements of individual sea catfish, Arius felis, and sheepshead porgy, Archosargus probatocephalus, were monitored electronically in a multiple‐choice rosette tank immediately after 72‐h static exposure to copper (0.0, 0.1, 0.2, or 0.4 mg Cu l−1) and 1 week later. Initial hyperactivity following copper‐exposure was exhibited by all fish of both species (except controls), as indicated by significant changes in the behavioural variables used to quantify locomotor activity. In addition, the orientation angles of successive movements in the monitor tank increased significantly for sea catfish, producing a decrease in the frequency of turning. Orientation angles of sheepshead showed a significant enhancement of the ‘normal’ tendency of this species to make small‐angle turns in the tank, and to return immediately to the compartment just vacated (indicative of an increase in the frequency of turning). One week following exposure, all copper‐exposed fish exhibited extreme hypoactivity which was significantly different from their behaviour immediately after exposure, and from the behaviour of control fish. This hypoactivity did not correspond, therefore, to ‘normal’ activity in either species. The delayed effect of copper exposure on orientation was to exacerbate significantly the species specific turning behaviour seen immediately following exposure. These results are discussed in terms of presumed accumulated physiological damage resulting from the exposure to copper and the initial hyperactivity such exposure elicits, and of general behavioural ecology.
Effects of copper on growth and starvation in perch, Percafluviatilis L.
Authors: Collvin L.
Published: January 2006

Non‐fed perch and perch fed a reduced ration were exposed to copper (0.15 of the 96‐h LC50) for 40 days. Starvation and growth rates were determined at 5‐day intervals to estimate the copper's effects on metabolism and food consumption. In general, copper increased starvation rates, reduced growth rates but did not affect food consumption. Weight reductions occurred in the first, but not in the second, 5‐day interval. There then followed an accelerated and linear weight reduction for 10–15 days, after which the rate of weight reduction was constant and at its highest level. Thus, perch did not acclimatize but a steady state of high metabolic cost was indicated over the last 20 days. The establishment and maintenance of this steady state was attributed to a detoxification mechanism. The increase in metabolic rate was, at steady state, estimated to increase the standard metabolic rate by at least 1.8 times. There was no apparent increase in specific dynamic action but increased activity due to an increase in competition for food was estimated to further increase the metabolic rate by 1.2 times.
Studies on feeding, growth and production of a recruited inshore population of Pleuronectes platessa (L.) at East Anglesey, North Wales
Authors: Basimi R. A. , Grove D. J.
Published: January 2006

Trawl surveys in an area of 237 km2 to the east of Anglesey (Irish Sea) indicated a population of recruited plaice (c. 480000 fish) between 2 and 15 years old. Seasonal growth began in early April and annual growth in the dominant cohorts was analysed for males and females separately. Net annual production was estimated to be 0.17 g m‐2 from a standing crop of 0.3 g m‐2; c. 50% of the production is removed by fishing. The annual consumption (2.5 g m‐2) of Abra and Pectinaria was converted with 6.8% efficiency by weight (8.0% in energy units).
Fundamental research problems in the management of Atlantic salmon, Salmo salar L., in Atlantic Canada
Authors: Chadwick E. M. P.
Published: January 2006

There are two fundamental types of research problems facing the management of Atlantic salmon in Atlantic Canada. First, there are problems associated with assessment of individual and mixed stocks: these can be divided into estimating optimal spawning requirements, estimating current spawning escapements, and forecasting available harvests at least one year in advance. Second, there are problems related to the large number of Atlantic salmon stocks, at least 350, and the small number of biological staff. One solution to many of these problems is to focus research efforts on small index rivers where upstream and downstream fish migrations are counted and randomly sampled. These rivers can be used to estimate optimal yield and to forecast harvest in distinct geographical areas. They also provide base‐line data to examine phenomena such as fluctuations in ocean survival, density‐dependent growth and mortality, or even large‐scale environmental perturbations.
The factors limiting growth and survival of brown trout, Salmo trutta m.fario L. introduced to different types of streams
Authors: Zalewski M. , Frankiewicz P. , Brewinska B.
Published: January 2006

Fingerlings of brown trout (Salmo trulta m. fario L.) were introduced to sections of different types of streams situated in natural catchments and those modified by Man's activity. At stations where environmental conditions were modified by such forms of impact as pollution, flow variability and impoundment, trout did not survive 5 months. In the natural river sections mortality rates increased downstream along the river continuum and were associated with increased predation. Growth rates in the upper reaches were primarily restricted by abiotic factors—temperature and trophic status: however, they were to a large extent modified by density‐dependent regulation and intraspecific competition. The influence of the abiotic/biotic regulatory process, expressed as fish metabolic performance, is discussed as a framework for the determination of the carrying capacity of the riverine ecosystem.
The environmental impact of salmonid cage culture on inland fisheries: present status and future trends
Authors: Phillips M. J. , Beveridge M. C. M. , Ross L. G.
Published: January 2006

This paper briefly reviews the environmental impact of the cage culture of salmonids in fresh waters, and evaluates the effects of this fish farming practice on the growth, behaviour and diseases of inland fish populations, concentrating on relationships between rainbow trout cage culture and indigenous brown trout populations. Possible future developments in salmonid cage culture are also discussed and the implications of this development for inland fisheries evaluated. The paper argues that the development of models should enable improved prediction of eutrophication from cage culture, to the benefit of the fish farmer, inland fisheries and other freshwater users, but also identifies a clear need for research in other areas of possible conflict.
Environmentally‐induced fluctuations in year‐class strength and their implications for management
Authors: Mills C. A. , Mann R. H. K.
Published: January 2006

Data for river populations of common freshwater species including dace, chub, roach, gudgeon and pike are examined to assess the magnitude of natural density‐independent fluctuations in the strength of year‐classes. Both in the cyprinid populations and in those of some salmonids, only occasional years give rise to large cohorts of adult fish. Correlations with temperature indicate that for the cyprinid populations these are often years when temperatures are high. In the River Frome, Dorset there is a significant relationship between the growth of O‐group dace and subsequent year‐class strength. Faster‐growing larvae may be better able to avoid predation. Both the habitat and feeding requirements of these young fish are different from those of the adults. A practical approach to improving recruitment in a population of a given species would be to first characterize, and then increase, the availability of suitable habitats and food organisms for the larval stages.
An approach to the prediction of temperate freshwater fish communities
Authors: Henderson P. A.
Published: January 2006

The organization and structure of temperate fish communities is discussed. A measure of organization based on the Shannon measure of entropy is applied. It is concluded that the way organization changes with species number reflects the underlying structure of the community. The prediction of fish assemblages by the analysis of individual species requirements is also investigated using fish data sets from regions considered to be undergoing acidification. The species set within a habitat is generated by a set of rules termed the operational niche. It was concluded that an analysis based on physico‐chemical conditions within the habitats gave reasonable correspondence between observed and predicted.