bluuebunny/crossref_metadata_2025_split huggingface dataset:
Movements of brown trout, Salmo trutta, and juvenile Atlantic salmon, Salmo salar, in a coastal stream in northern Norway
Authors: Hesthagen T. 
Published: January 2006

Movements of resident brown trout (age 2+ to 9+ years) and young Atlantic salmon (age 1+), stocked as fry, were studied in July, August and September in a coastal stream in northern Norway. Between 85 and 89% of the brown trout were recaptured in the study area (346m, 1326m2) within 45m of their release point throughout the investigation period. Most specimens had moved less than 150m. Trout movements were related to local variation in density. Trout occupying those sections of stream with the lowest fish densities (5.3–10.9 fish 100m−2) had a significantly lower movement rate than fish from sections with densities between 13.7 and 31.5 fish 100m−2. Trout that moved from their marking section were significantly larger than specimens that did not leave their original site. There was a significant correlation between permanence of station each month and the mean water level that month. The majority of the trout (47%) were caught at undercut stream banks or at sites in the proximity of these. A decrease in water level during the study period resulted in a high loss (36%) of such habitat, probably forcing some individuals to move. The recapture data indicate that the trout population consists of one small (c. 15–20%) mobile, and one large sedentary component.Young salmon displayed high station permanence in July and August (93% and 96%). However, in the autumn they exhibited a significant downstream movement, and only 73% were recaptured within their release section. This movement was significantly higher for larger specimens, and is thought to occur because of a pre‐winter change in habitat, initiated by a decline in stream temperature. In contrast to trout, salmon in sections containing the lowest densities (22.0–25.0 fish 100m−2) did not show significantly lower movement rates when compared with salmon at higher densities (32.2–46.3 and 51.8–60.6 fish 100m−2). The spatial distribution of young salmon indicated the formation of territorial mosaics over the stream bed, which are thought to reduce intraspecific competition.
Sound production by the gudgeon, Gobio gobio L., a common European freshwater fish (Cyprinidae, Teleostei)
Authors: Ladich F. 
Published: January 2006

Acoustic signals emitted by the gudgeon are described and the context of sound production is considered.In aquaria, gudgeons produce creaking sounds of differing duration, which are always built up of single bursts. Each burst is composed of a series of rapidly repeated short pulses. Vocalization is correlated with the level of activity: it increases at higher temperatures and decreases when fish are disturbed. After acclimatization to the aquarium, fish which formerly showed a diurnal pattern of activity became active at all times of the day and night. Gudgeon called as a reaction to digging by other members of the group and a variety of disturbances, the latter including being touched or hindered by a conspecific or being frightened by the sudden movement of another fish. The fact that only certain interactions in a gudgeon shoal are accompanied by sound production is discussed.
Ultrastructural and cytochemical observations on the granulocytes of the sturgeon, Acipenser brevirostrum (Chondrostei)
Authors: Hine P. M. , Wain J. M. 
Published: January 2006

Granulocytes from cranial granulopoietic tissue were studied under the electron microscope, and cytochemistry carried out oncranial and peripheral blood granulocytes of two sturgeons, Acipenser brevirostrum. Ultrastructurally, eosinophils and basophils had homogeneous electron‐dense granules similar to those of teleosts and some higher vertebrates. Neutrophils contained two granule types: small elongated fibrillar granules and large (<3.8μm long) usually homogeneous granules.Neutrophil fibrillar granules were positive for alkaline phosphatase (ALP), acid phosphatase (ACP), α‐naphthyl acetate esterase (ANAE), acetyl‐l‐tyrosine‐α‐naphthyl esterase (ATNE) and periodic acid Schiff (PAS) reaction. The large homogeneous granules were negative for all enzymes, and were only PAS positive. Eosinophils had granular, cyanide‐, azide‐ and aminotriazole‐resistant peroxidase (PO) and were ACP, ATNE, tosyl‐l‐lysine‐α‐naphthyl esterase (TLNE) and Luxol fast blue positive.Ultrastructure and cytochemistry are discussed in relation to other vertebrates, and eosinophils identified as the main phagocytic leucocyte.
Observations on the granulocyte peroxidase of teleosts: a phylogenetic perspective
Authors: Mine P. M. , Wain J. M. 
Published: January 2006

Observations on granulocyte peroxidase of 123 teleosts are reported and correlated with previous studies to put occurrence of fish granulocyte peroxidase in a phylogenetic perspective. Eosinophil peroxidase occurs in archaic groups such as lungfish and sturgeons, but is usually weak and infrequently observed in chondrichthyans, and in teleosts occurs in some elopomorphs, is consistently observed in stomiiforms, is rarely observed and usually weak in acanthopterygians and absent from salmoniforms, scopelomorphs and paracanthopterygians. Peroxidase is absent from lungfish and sturgeon neutrophils, is present in neutrophils of some elopomorphs and clupeimorphs. both of which are basal teleost groups, but in salmoniforms and higher teleosts is consistently observed in neutrophils. although often weak in pleuronectiforms.Loss of eosinophil peroxidase and development of neutrophil peroxidase in teleosts may be due to inefficient phagocytosis and loss of peroxidase with degranulation in eosinophils, being superseded by concentration of peroxidase in phagosomes in neutrophils.
Aspects of energetics of adult walleye pollock, Theragra chalcogramma (Pallas), from Alaska
Authors: Smith R. L. , Paul A. J. , Paul J. M. 
Published: January 2006

Body energy partitioning was examined for field‐caught, adult walleye pollock; additional laboratory studies were conducted on fish held under controlled temperature conditions at Seward, Alaska.Average consumption for pollock feeding daily was 0.5% of body weight (3100 cal) at 5°C, resulting in an average growth of 0.12% body weight day−1. These results suggest that large pollock grow at similar rates and have similar food conversion efficiencies to those of Atlantic cod held at similar temperatures.Resting metabolic rates measured on adult fish were combined with similar data from juveniles to calculate a regression of specific metabolic rate against wet weight: y= 173x−026. Maintenance rations amounted to 4.8 cal g−1 day−1 at 5°C, very close to the 0.28% value for juveniles. Estimation of metabolic rate using maintenance ration data resulted in values that were 55% higher than those obtained from oxygen consumption data for unfed fish. Weight loss during starvation was 0.18% of body weight day−1 at 5°C, corresponding roughly to a starvation metabolic rate 50% lower than the resting metabolic rate we report.We estimate that an adult pollock will lose about 37% of its prespawning body weight and about 46% of its body energy during spawning. These losses result, primarily, from changes in the weight of gonad, liver and somatic tissues as opposed to changes in specific energy content of those tissues.
Pre‐adaptive plasticity in atherinids and the estuarine seat of teleost evolution
Authors: Bamber R. N. , Henderson P. A. 
Published: January 2006

With the aid of models and selected examples, an analysis of speciation within the family Atherinidae is presented. This is a large family of pelagic fish, many members of which look strikingly similar. They are primarily a marine coastal group, favouring sheltered estuaries and lagoons, although in some regions they have invaded fresh waters.Many atherinids show a high degree of intraspecific morphological variability which can be linked to their estuarine habitat. It is argued that estuarine and lagoonal environments are physically highly variable and this has acted to select for generalist genotypes able to adjust their morphology, physiology and behaviour to a wide range of conditions. Such plasticity pre‐adapts atherinids to invade and rapidly speciate in fresh waters containing vacant niches. Examples of such invasions and speciation are presented, and the rate of evolution discussed.The selective forces acting on atherinids should be common to other fish groups, suggesting that many freshwater fish may have estuarine ancestors. The influence of estuaries in evolution may be out of all proportion to their size.
Population dynamics and community structure of fish in the mangroves of Pagbilao, Philippines
Authors: Pinto L. 
Published: January 2006

128 fish species were recorded for the mangroves of Pagbilao. Aspects of the population dynamics of the common species, Ambassis kopsi, Secutor ruconius. Leiognathus brevirostris and Prosopodasys gogorzae were investigated. Growth coefficients varied from 0.41 to 1.2. Mortality in the mangroves was high, and most species there breed once per year.Species diversity (H') of the community ranged from 1.05 to 2.9. It was influenced by evenness rather than by species richness. Species abundance gave a log normal distribution, except during the typhoon, when it fitted the niche preemption model.
A review of information relating to fish passage through turbines: implications to tidal power schemes
Authors: Davies J. K. 
Published: January 2006

Field and laboratory studies on the passage of adult and juvenile fish through hydroelectric turbines are reviewed, with special emphasis on tidal schemes in operation. Although the types of injury which fish incur and their frequency are well documented, little appears to be known about the specific hydraulic conditions within the turbine structure which actually cause the injury, despite the fact that the four main causes of fish loss (abrupt changes in pressure, water turbulence, shearing currents and mechanical contact with turbine blades) have been identified.Factors causing fish mortality fall into two main categories: (a) hydraulic conditions of pressure change, cavitation, shearing and turbulence, producing direct, characteristic injuries; (b) conditions influencing the likelihood of actual fish collision with turbine components. These factors can be enhanced or reduced by alterations in turbine operation and, possibly, design.The significance of fish behaviour and ecology with respect to prediction of numbers of fish passing through installations, plus criteria which govern actual mortality rates have yet to be elucidated.
The effect of calcium concentration on the toxicity of copper, lead and zinc to yolk‐sac fry of brown trout, Salmo trutta L., in soft, acid water
Authors: Sayer M. D. J. , Reader J. P. , Morris R. 
Published: January 2006

Yolk‐sac fry of brown trout were exposed to three levels of single trace metals (Cu, 20,40,80 nmol 1‐1; Pb, 12·5,25,50 nmol 1‐1; Zn, 75,150,300 nmol 1‐1) typical of concentrations reported for acid soft waters, in flowing, artificial, soft water media maintained at pH 4·5 and [Ca] of 20 or 200 μmol 1‐1for 30 days.Mortalities were high in fry subjected to all levels of the three trace metals at [Ca] 20 μmol 1‐1, with 80% of the total deaths occurring between days 11 and 15 of the experiment. 25% mortality occurred at low [Ca] and pH 4·5 in the absence of trace metals, with only one death recorded at [Ca] 200 μmol1‐1’(Cu, 80 nmol 1‐1). At high [Ca] all three levels of Cu and Pb impaired net Na and K uptake; Cu was the only metal to reduce the uptake of Ca. The Zn treatments had no significant effect on mineral uptake. Calcification of centra was reduced by all three Cu treatments at [Ca] 200 μmol 1‐1. The lowest Zn concentration (75 nmol 1‐1) was the only other treatment to impair skeletal development. In the absence of trace metals, low [Ca] significantly reduced Ca, Na and K uptake, skeletal calcification and dry mass at pH 4·5.The deleterious effects of low Cu, Pb and Zn concentrations at low pH and low [Ca], and the ameliorative effect of higher ambient [Ca], are discussed in relation to fishery status in soft, acid waters.
The effects of prey relative abundance and chemical cues on prey selection in rainbow trout
Authors: Bres M. 
Published: January 2006

An optimal foraging model was used to predict prey selection based on both energy maximization and number maximization strategies. The influence of chemical cues and relative abundance on rainbow trout diet selection was examined under laboratory conditions.In most fish, diet composition was strongly influenced by chemical cues. No fish followed an energy maximization strategy, and selection of prey based on taste persisted despite large caloric penalties associated with these choices. In the absence of chemical cues, diet composition was based on relative abundance of prey (a number maximization strategy). Within the feasible constraints of the optimal foraging model lie a large number of possible diet combinations which would provide sufficient energy for growth and reproduction. This provides a wide scope for feeding flexibility. Response to prey chemical cues may be the basis for observations of individual diet variability in trout.
Analysis of the enzyme polymorphism in a plaice, Pleuronectes platessa L., population from the north‐west coast of Brittany, France
Authors: Brulé T. 
Published: January 2006

A study of enzyme polymorphism by electrophoretical techniques permitted the genetic structure and the homogeneity degree of the plaice population present in the Abers Wrac'h and Benoit along the north‐west coast of Brittany to be determined. Thirteen enzymic systems encoded by 21 loci were analysed and nine of these loci were polymorphic at the 5% level. The comparison of allelic frequencies and of observed heterozygosity hobs did not show significant differences between these two individual groups. Nei's genetic identity (I= 0.998) and distance (D= 0.002) as estimated from allelic frequencies showed that the plaice of the two estuaries are very similar.Thus, the plaice of A. Wrac'h and of A. Benoit belong to the same population in which the average level of polymorphism per locus P is 47% and the observed average heterozygosity per individual Hobs is 0.163 ± 0.094.
Light and scanning electron microscopic studies on the effect of biocidal plant sap on the gills of a hill stream fish, Garra lamta (Ham.)
Authors: Ojha J. , Rooj N. C. , Mittal A. K. , Datta Munshi J. S. 
Published: January 2006

The effect of a biocidal plant sap (Terminalia tomentosa) on the gills of a swift‐current‐adapted hill‐stream fish, Garra lamia, has been investigated using light and scanning electron microscopy. The biocidal plant sap affected the dissociation of the gill filament and lamellar epithelia to expose their microvasculature. Some findings on the microvasculature are discussed in the light of their probable functions. Fusion of lamellae and prominent chloride cells are further effects of the plant sap, and their impact on respiratory and osmoregulatory functions of the fish are discussed.Use of biocidal plant sap in mass killing of hill‐stream fish is considered in relation to conservation.
Effect of fasting on glycogen metabolism and activities of glycolytic and gluconeogenic enzymes in the mudskipper Boleophthalmus boddaerti
Authors: Lim A.L.L. , Ip Y.K. 
Published: January 2006

During starvation, muscle glycogen in Boleophthalmus boddaerti was utilized preferentially over liver glycogen. In the first 10 days of fasting, the ratio of the active‘a’form of glycogen phosphorylase to total phosphorylase present in the liver was small. During this period, the active‘I’form of glycogen synthetase increased in the same tissue. In the muscle, the phosphorylase‘a’activity declined during the first 7 days and increased thereafter while the total glycogen synthetase activity showed a drastic decline during the first 13 days of fasting.The glycogen level in the liver and muscle of mudskippers starved for 21 days increased after refeeding. After 6 and 12 h refeeding, liver glycogen level was 8·5 ± 2·3 and 6·9 ± 4·5 mg·g wet wt 1, respectively, as compared to 5·8 ± l·6mg·g wet wt 1 in unfed fish. Muscle glycogen level after 6 and 12 h refeeding was 0·96±0·76 and 0·82 ± 0·50 mg·g wet wt 1, respectively, as opposed to 0·21 ± 0·12 mg·g wet wt 1 in the 21‐days fasted fish. At the same time, activities of glycogen phosphorylase in the muscle and liver increased while the active‘I’form of glycogen synthetase showed higher activity in the liver. Since glycogen was resynthesized upon refeeding, this eliminated the possibility that glycogen depletion during starvation was due to stress or physical exhaustion after handling by the investigator.Throughout the experimental starvation period, the body weight of the mudskipper decreased, with a maximum of 12% weight loss after 21 days. Liver lipid reserves were utilized at the onset of fasting but were thereafter resynthesized. Muscle proteins were also metabolized as the fish were visibly thinner. However, no apparent change in protein content expressed as per gram wet weight was detected as the tissue hydration state was maintained constant. The increased degradation of liver and muscle reserves was coupled to an increase in the activities of key gluconeogenic enzymes in the liver (G6Pase, FDPase, PEPCK, MDH and PC). The increase in glucose synthesis was possibly necessary to counteract hypoglycemia brought about by starvation in B. boddaerti.
Gastric evacuation rates and daily ration of piscivorous coho salmon, Oncorhynchus kisutch Walbaum
Authors: Ruggerone G. T. 
Published: January 2006

Effects of temperature and meal size on gastric evacuation rates of juvenile coho salmon, Oncorhynchus kisutch, consuming sockeye salmon, O. nerka, fry were examined and used in the estimation of daily meal, daily ration and number of fry consumed by coho in Chignik Lake, Alaska. Evacuation of fry by coho was best described by a negative exponential model (average R2= 0.93). A square root model also provided a good fit (average R2= 0·93), but the y‐intercepts deviated more from the expected value than did the y‐intercepts of the exponential model. The effect of temperature (T, 5–13° C) and meal size (MS, 0·166–0·367 g) on the exponential evacuation rate (re, h‐1) could be described as
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In the lake, coho fed continuously during the 24‐h period in early June 1986 and 1987. Estimates of daily meal and ration of coho calculated by the Eggers method and the geometric mean of prey weight ranged from 0·224 to 0·435 g (2.1–4.4% body wt) depending on location and year. The Elliott & Persson method provided similar estimates of food consumption, whereas estimates based on the Pennington method and square root evacuation of prey differed from the exponential models. Sockeye fry represented 93% of the total prey weight. The average number of sockeye fry consumed per coho per 24 h, based on the arithmetic mean of prey weight, was 3·0–3·9 fry.
Some Spanish cestode fish parasites
Authors: Durán M. L. Sanmartín , Alonso P. Quinteiro , Rodriguez A. , Fernándeez J. A. 
Published: January 2006

Cestode fish parasites were studied in 569 fish of 13 species, comprising 72 specimens of Hyperoplus lanceolatus caught between April and July 1987 and 497 other fish caught between December 1986 and March 1987 at 42° 45′ N, 9° 26′ W (Table I). Bothriocephalus was found for the first time in H. lanceolatus, though its prevalence was very low. The presence of these larvae in a species that forms part of the turbot's Scophthalmus maximus food chain suggests that they may infect the turbot via H. lanceolatus as well as via copepods. Dupond & Gabrion (1986) and Robert et al. (1988)
Seasonal and regional infestation characteristics of three ectoparasites of whiting, Merlangim merlangus L., in the North Sea
Authors: Pilcher M. W. , Whitfield P. J. , Riley J. D. 
Published: January 2006

Whiting collected from 36 stations in the North Sea in August 1985 and February 1986 were examined with reference to the prevalence, intensity and microhabitat utilization of three ectoparasites, namely Lernaeocera branchialis (Copepoda: Pennellidae), Clavella adunca (Copepoda: Lernaeopodidae) and Diclidophora merlangi (Monogenea: Polyopisthocotylea). Maximum prevalences and mean intensities, at any one station, for the three parasites were 74,45.48,60% and 1.07,0.56 and 1.30, respectively.At the stations sampled, infestation levels with L. branchialis and C. adunca were significantly higher in the winter than in the summer, with winter mean parasitic intensities being between five and eight times higher than those in summer. A converse situation applied with D. merlangi, with summer mean intensities being over four times larger than those in winter.Pooled winter and summer parasitic infestation data, from the 36 stations, enabled large‐scale zoogeographical parasitization patterns to be recognized. Both L. branchialis and C. adunca are rarely seen on whiting in the North Sea north of latitude 56° N. South of this latitude, prevalences and intensities of L. branchialis are higher on the eastern than on the western side of the sampling zone, while those of C. adunca are similar on both sides of the North Sea. D. merlangi's infestation exhibits a striking latitudinal cline in the study area, with prevalences and intensities increasing steadily from south to north.All three ectoparasites were non‐randomly distributed within the whiting gill and/or buccal cavities and showed marked microhabitat preferences. Possible explanations for the seasonal and geographical variations in the parasitic infestations are discussed.
A comparative study of the epidermis of the common carp and the three Indian major carp
Authors: Singh S. K. , Mittal A. K. 
Published: January 2006

A comparative study has been made of the mucogenic epidermis of the common carp, Cyprinus carpio var. communis, and the three Indian major carps, Catla catla, Labeo rohita and Cirrhina mrigala: on the basis of epidermis structural organization, these species are easily differentiated.The epithelial cells in the superficial layer, as in most fishes, show secretory activity, evidenced by positive histochemical reactions, which is high in C. carpio var. communis, moderate in C. catla and low in L. rohita and C. mrigala. The epithelial cells in the underlying two or three layers also give positive reactions, though their intensity is relatively weak.The mucous cells in C. carpio var. communis are distributed in large numbers arranged in several superimposed layers in the outer regions of the epidermis, whereas in C. catla they are fewer in number and are widely separated in the surface layers as well as in the deeper layers of the epidermis; in both species the mucous cells appear rounded, large, and open on the surface by wide pores. In contrast, in L. rohita and C. mrigala the mucous cells are smaller, restricted mainly to the superficial layer, close together in a single row, and open on the surface by narrow pores. The overall density of mucous cells in L. rohita and C. mrigala, as in C. catla, is much lower than in C. carpio var. communis.In the epidermis of C. carpio var. communis there are a large number of mucous cells, and the few club cells are restricted to the deeper layers. In contrast, in the epidermis of the three Indian major carp the overall density of the mucous cells is much lower and the club cells are very numerous. It is suggested that the high density of club cells compensates an overall low density of mucous cells as an adaptation for an effective defence mechanism.Increased mucus production in the epidermis of C. carpio var. communis, as evidenced by a large number of mucous cells in outer regions and high secretory activity of superficial layer epithelial cells, is associated with increased precipitation of mud held in suspension, needed as an adaptation to the species’peculiar bottom‐scooping habits.The varied density of the taste buds in the epidermis of the four carp is associated with their feeding habits.