bluuebunny/crossref_metadata_2025_split huggingface dataset:
An automated method for counting and sizing fish eggs
Authors: Witthames P. R. , Walker M. Greer 
Published: January 2006

This paper describes an automated method for counting and sizing fish eggs in the diameter range 200–2500 μm. Eggs, suspended in water, are pumped at a controlled rate through an electronic sensor which produces a voltage pulse which is proportional in amplitude to particle size. The sensor is connected to a HIAC Criterion PC‐320 particle analyser which is in turn connected to a Tracor Northern pulse height analyser. This equipment separates the voltage pulses into 398 recording channels. An ACT 1 Sirius microcomputer is used to store the data, transform it to egg size and then produce a histogram of egg size distribution in 20‐μm class intervals.The method has a counting accuracy of 99.5 ± 0.5%. It has been compared with two manual methods of estimating egg numbers.
Size characteristics and diet of emergent chinook salmon in a small, stable, New Zealand stream
Authors: Field‐Dodgson M. S. 
Published: January 2006

The emergence timing, quality and diet of chinook salmon, Oncorhynchus tshawytscha, fry were studied as they emerged from ten natural redds. The impact of selected environmental factors on emergence was studied also. Samples of fry were obtained daily using redd traps.The mean period of total emergence for redds with more than 450 fry emerging was 44.8 days (range 25–57 days), but for 80% of the fry in each redd to emerge the mean time elapsed was 10.8 days (range 6–21 days). No fry sampled had a visible yolk sac. The effect of temperature and light on emergence timing was weak, but stream flow had a strong influence. Fry length was constant for each redd throughout emergence, but fry weight tended to decline; consequently condition factor declined also. There was evidence that fry fed before emergence, but they did not grow. The major prey item, Deleatidium spp. (47.4% of the contents of all stomachs sampled), was the most abundant invertebrate in stream benthos and drift. Empty stomachs were prevalent at the start of emergence, with full stomachs becoming more common as emergence progressed.The time distribution of numbers of fry emerging was usually unimodal, but occasionally bimodal. Over one third of fry emerged during the best 2 days of sampling.
Bioenergetic model of planktivorous fish feeding, growth and metabolism: theoretical optimum swimming speed of fish larvae
Authors: Darowski K. , Takashima F. , Law Y. K. 
Published: January 2006

The feeding activity of an individual fish larva is described by an equation which includes parameters for the area successfully searched, probability of food capture multiplied by the cross‐sectional perceptive visual field, larval swimming speed and the time required to consume a unit of food energy. The proportion of ingested food energy used for metabolism increases exponentially with increasing swimming speed. The model predicts that food consumption rate increases asymptotically whereas metabolic rate increases exponentially. This results in a predicted growth rate curve that reaches a maximum at a certain swimming speed and decreases at both higher and lower speeds.The model can be used to predict the influence of type of prey, prey density, water temperature etc. on larval growth. An expression describing how many hours per day fish larvae must forage in order to grow at a certain daily body weight gain allows the limits of environmental conditions for positive, zero and negative growth rate to be set.Results of simulations demonstrated that the optimum swimming speed for maximum growth of coregonid larvae increased with an increase in food density, decrease in water temperature or decrease of prey vulnerability. At optimum ‘theoretical’ swimming speed an increase in water temperature from 5 to 17° C required the food density to be increased from 20 to 80 copepods l−1 in order to maintain a daily growth increment of 2%. The minimum Artemia density required for maintenance metabolism increased from 10 to 30 items 11 over the same temperature increase from 5 to 17° C, and food densities required for 8% growth rates were 26 and 56 Artemia nauplii l−1 at 5 and 17° C, respectively.Contrary to previous findings, results of the present study suggest that metabolic rates of actively feeding fish larvae may be from 5 to 50 times the standard metabolic rate: earlier studies suggested that a factor of 2–3 may be generally applicable.
Occurrence of parasites of the freshwater mugilid fish Liza abu (Heckel) from Basrah, southern Iraq
Authors: Mhaisen F. T. , Al‐Salim N. K. , Khamees N. R. 
Published: January 2006

In monthly samples of Liza abu collected November 1981–October 1982 from Mehaijeran Creek, a western branch of Shatt–Al–Arab river south of Basrah, fishes were infected with the third larval stage of the nematode Contracaecum sp., the acanthocephalan Neoechinorhynchus agilis and the gill crustacean Ergasilus mosulensis.Generally, the changes in the percentage prevalence coincided with the changes in the mean intensity of infection. There were no significant differences between the infection of male and female fishes in the cases of the monthly variations of infection with Contracaecum sp. and of infection with both Contracaecum sp. and E. mosulensis, according to fish length, but in other cases more female fishes were infected than males.Infection with Contracaecum sp. decreased gradually in the larger fishes. In the case of both N. agilis and E. mosulensis, the infection at first increased with increase in fish length but decreased in larger fishes.Infection with Contracaecum sp. occurred only during May–August and disappeared during September. The peak for N. agilis was in April, and it disappeared during summer. Infection with E. mosulensis disappeared during winter months.
Thermal enrichment of a reservoir and the effects on annulus formation and growth of largemouth bass, Micropterus salmoides
Authors: Galloway M. L. , Kilambi R. V. 
Published: January 2006

Analysis of largemouth bass scales, including those from 48 tagged and recaptured fish, revealed that many scales had more ‘annuli’ than possible for the age of Flint Creek Cooling Reservoir. The mark‐recapture data indicated the formation of one supernumerary annulus per year for most bass. Time of formation of true and supernumerary annuli and the causative factors are discussed.Growth of bass from this reservoir greatly exceeded that reported for thermally unaltered reservoirs of Northwest Arkansas, due to the existence of a nearly year‐round growing season, a result of thermal enrichment. The relationship between the ratio of electric power output to reservoir surface area and growth offish was evaluated with reference to published data on cooling reservoirs.
The relationship between nitrogen output and changes in mucous cell function in the amphibious teleost Blennius pholis L. during aerial exposure
Authors: Sayer M. D. J. , Blackstock N. 
Published: January 2006

The numbers of mucous cells in the epidermis of the head and body and in the surface of the gill arch of the amphibious blenny, Blennius pholis L., were estimated on fish immersed in sea water and after 4 h aerial exposure. During emersion there appeared to be a considerable reduction in the frequency of epithelial mucous cells in the areas studied, although counts for the head epidermis were somewhat variable. A concomitant decline in the number of cells thought to be actively secreting was also recorded in tissue samples from both the head and gills, while in the body epidermis the potential for mucus‐secretion was maintained close to the levels observed in immersed fish.Histochemical studies revealed epidermal mucous cells containing either sialylated acid mucopolysaccharides or neutral mucins, or a mixture of these, in both the head and the body, whereas in the gill arch epithelia there were, in addition, cells containing sulphated acid mucopolysaccharides. After emersion, a disproportionate loss of cells containing neutral and sialylated mucus from the gill epithelia resulted in an increase in the proportion of secreting cells staining positively for sulphated acid mucopolysaccharides.The results of this study are discussed in relation to nitrogenous excretion during aerial exposure.
Digestive efficiency and nutrient composition gradient in the gut of Oreochromis niloticus L. in Lake Awasa, Ethiopia
Authors: Getachew T. 
Published: January 2006

Assimilation efficiencies were measured by comparing the amount of nutrient in the food and faeces of fish from the natural environment. The comparison of nutrients was made in relation to reference markers: ash, hydrolysis‐resistant ash (HRA) and hydrolysis‐resistant organic matter (HROM). Assimilation efficiencies of nutrients computed using ash and HRA as reference markers were significantly (P < 0.05) lower than those measured with HROM; digestibility estimates of protein were the least influenced by the type of marker used. Generally, HROM appears to be the most suitable reference marker for a digestibility study in an herbivorous fish such as Oreochromis niloticus.Nutrient composition gradient examined by analysis of stomach, intestinal and rectal contents showed that digestion of all nutrients was completed when the food passed two‐thirds of the way through the length of the intestine. Most of the nutrients were significantly (P < 0.05) affected by the processes of digestion and assimilation in different sections of the gut, and a decline in the quantity of nutrients was obvious towards the rectum.
Feeding habits of the Lessepsian migrant Siganus luridus in the eastern Mediterranean, its new environment
Authors: Stergiou K. I. 
Published: January 2006

The feeding habits of the Lessepsian migrant Siganus luridus in the eastern Mediterranean (Kastellorhizo Isle, Dodecanese, Greece) are examined. The stomach contents of 209 specimens, 131–250 mm total length, collected by bottom trammel nets, April 1985 July 1986, were analysed. Feeding intensity was high, although it significantly declined during the spawning period in summer. Siganus luridus feeds on a diverse assemblage of benthonic algae including 24 genera (seven green, eight brown and nine red algae) contributing 84.4% by weight (green algae 3%, brown 70.3%, red 11 %). Posidonia oceanica, diatoms, hydrozoa and sand were also found in the stomachs examined. On an annual basis, Dictyota sp., Cysloseira sp., Sphacelaria sp., Gelidium sp., Dictyopteris membranacea, Kuckuckia spinosa and Padina pavonica predominated in the diet. Diet overlap, on a weight basis, indicated a similar food spectrum during spring and summer which was different from that in autumn.The high feeding intensity of S. luridus during the year (except for the spawning period), its nonselective euryphagous nature, its high competitive potential, and its position in the food web of the eastern Mediterranean ecosystem are important characteristics that, along with suitable oceanographic and ecological conditions for the development and survival of young stages, have enabled the successful establishment and build‐up of the population of this Lessepsian migrant in its new environment. Possible competitive implications in the eastern Mediterranean ecosystem are also discussed.
Otolith resorption induced by anaerobic stress in the goldfish, Carassius auratus
Authors: Mugiya Y. , Uchimura T. 
Published: January 2006

To examine otolith resorption induced by anaerobic stress, 45Ca‐prelabelled goldfish, Carassius auratus, were kept in oxygen‐deficient ambient water (O2 < 0.5 .1 1−1, 26° C) for 2 days and otoliths (asterisci) were analysed for 45Ca retention. In a second experiment, fish were anaerobically stressed for 2 days, and then received a single intraperitoneal injection of 45Ca. They were maintained under stress for one more day and killed to examine 45Ca deposition in otoliths. Plasma was analysed for total and radioactive calcium. Otoliths (lapilli) were examined for stress‐induced check formation by scanning electron microscopy (SEM).Stress significantly reduced plasma calcium levels and the rate of calcium retention in otoliths, which was calculated from the 45Ca specific activity of the plasma. On the other hand, the rate of calcium deposition in otoliths was the same in the stressed as in the control fish. SEM observation revealed that the applied stress resulted in a check formation in otoliths. These results indicate that a 48‐h stress of oxygen deficiency induces calcium resorption in otoliths.
Ultrastructural alterations in branchial chloride cells of Atlantic salmon, Salmo salar, during parr‐smolt transformation and early development in sea water
Authors: Lubin R. T. , Rourke A. W. , Bradley T. M. 
Published: January 2006

The ultrastructure of the gill primary lamellae of juvenile Atlantic salmon was examined during the parr‐smolt transformation and for 42 days after smolts were exposed to sea water. Scanning electron microscopy indicated that primary lamellae were characterized by rough convoluted surfaces that became rougher throughout the experimental period and that crypts did begin to form in freshwater fish. Crypt formation increased in sea water.Transmission electron microscopy indicated that parr preadapt for life in sea water in part by changes in chloride cells. Chloride cells show an elaboration of rough endoplasmic reticulum in fresh water and a decline of rough endoplasmic reticulum after 42 days of sea water exposure. The tubular membrane system becomes well developed in fresh water, and apical vesicles become abundant only after seawater exposure. Mitochondria are both spherical and elongate through the period and contain well developed cristae. No evidence of mitochondrial rupture was observed. The junctions between chloride cells and adjacent cells were characterized in fresh water by long tight junctions with desmosomes. This type of junction continued in sea water and was the norm between chloride cells and accessory cells after 42 days of seawater exposure. While leaky junctions appeared to be forming, no evidence was found of membrane interdigitation between accessory cells and chloride cells after 42 days of seawater exposure. It also appeared that seawater exposure influenced the number of chloride cells exposed to the external milieu.Pavement cells showed an elaboration in fresh water of free ribosomes and rough endoplasmic reticulum and these elements became less prominent after seawater exposure.
Histochemical characterization of myotomal muscle of five teleost species
Authors: Gill H. S. , Weatherley A. H. , Lee R. , Legere D. 
Published: January 2006

A histochemical study was performed on the myotomal musculature of five teleost fish from four families (longnose dace, Rhinichthyes cataractae; bluegill, Lepomis macrochirus, smallmouth bass, Micropterus dolomieul; yellow perch, Perca flavescens; lake whitefish, Coregonus clupeaformis). Three main types of fibre (red, pink, white) were distinguished in these species on the basis of relative activities of actomyosin adenosine triphosphatase (ATPase) and NADH diaphorase. White muscle formed the bulk of the myotomal musculature. The proportion of red muscle was greater in the caudal region (11·–5% of the total cross‐sectional area) than in more anterior regions of the body in all the species. Pink fibres comprised only a transitional layer (cells deep) between red and white. In bluegill, the red fibres penetrated deeper medially from the superficial lateral position than in the other four species.It appears that, among the present five species, the somewhat greater amount of red muscle in yellow perch may be related to the free‐cruising sometimes associated with that species, compared to the more desultory activity of the other four. It is noted that the amount of red muscle relative to white is appreciably greater in all five species than that revealed in two esocid species in an earlier study; the latter are‘ ambush predators’that swim very rapidly towards prey.
Size of prey ingested by whitefish, Coregonus sp., larvae. Are Coregonus larvae gape‐limited predators?
Authors: Ponton D. , Müller R. 
Published: January 2006

The feeding ecology of whitefish, Coregonus, larvae in oligotrophic Lake Sarnen and eutrophic Lake Hallwil is presented, taking into consideration the size of the prey ingested in relation to the mouth size of larvae and to the availability of zooplankton.When larvae grow from 10 to 16 mm their mouth width increases from 500 to 1000 μm while their gape height, with the mouth open at 45 and 90°, increases from 200 to 400 μm and from 400 to 700 μm, respectively, whichever lake is considered.The differences found in the mean prey width between the two lakes arise in part from the composition of diets, and in part from differences in size of the available prey organisms. Whatever the origin of the larvae and the taxon we consider, larvae seem to ingest the most abundant prey size without selecting the biggest ones available even if, from a mechanical point of view, they would be able to ingest them.Taking into account the generally low density of zooplankton in the uppermost layer of the lake, we conclude that whitefish larvae eat in the manner such as to decrease the cost of prey capture, in terms of energy and time, by choosing the more abundant prey available.
Orientation of carp, Cyprinm carpio L., to free amino acids from Tubifex extract in an olfactometer
Authors: Saglio Ph. , Fauconneau B. , Blanc J. M. 
Published: January 2006

We analysed the effects of L‐amino acid combinations, tested at the same relative concentrations as in 500 mgl1 of a filtrated Tubifex extract, on attraction and exploratory behaviour of juvenile carp, Cyprinus curpio L., in an olfactometer. Tubifex filtrate was significantly active in the range of concentrations tested (5 mgl−1, 50 mgl−1, 500 mgl−1, 5 gl−1). Maximum attraction was obtained in response to a concentration of 500 mg l−1. Soluble TCA fraction and a mixture of the 17 synthetic amino acids found in this fraction also showed significant effects on attraction and exploratory behaviour. Tests of the four chemical groups of amino acids gave the following results: acidic amino acids (aspartic and glutamic) did not produce significant activity. Basic amino acids (histidine, arginine and lysine) and polar, uncharged amino acids (glycine, serine, threonine, tyrosine, asparagine and glutamine) were ineffective as attractants but significantly increased exploration. Non‐polar amino acids (alanine, valine, leucine, isoleucine, phenylalanine, and methionine) showed significant effects on both attraction and exploration. In tests where different pairs of these amino acid groups were mixed it was shown that a combination of non‐polar amino acids and polar uncharged amino acids was the most effective in inducing both attraction and exploration. The simplest combination to have a significant effect on both attraction and exploration was alanine, valine and glycine.These results are discussed in the light of recent data on the role of free amino acids in the behaviour of fishes.
Opsonic effect of antiserum and complement on phagocytosis by macrophages from the peritoneal cavity of the Japanese eel, Anguilla japonica
Authors: Kaige N. , Miyazaki T. , Kubota S. S. 
Published: January 2006

Macrophage exudates in the Japanese eel, Anguillu japonica, were induced by intraperitoneal injection with a mixture of Edwnrdsiella bacterin, proteose peptone and liquid paraffin, and the opsonic effect of antiserum and complement on the phagocytic activity of the macrophages was studied.The macrophages contained a round nucleus with a nucleolus, and an agranular cytoplasm with projecting processes. These cells showed phagocytosis of sheep red blood cells (SRBC). An opsonic effect of antiserum was recognized in terms of a significant increase of macrophage phagocytic activity against SRBC treated with antiserum relative to that against SRBC treated with inactivated normal serum. Complement, however, did not enhance the phagocytic activity of macrophages.
Embryonic and larval development of brown trout, Salmo trutta L.: exposure to trace metal mixtures in soft water
Authors: Sayer M. D. J. , Reader J. P. , Morris R. 
Published: January 2006

Freshly fertilized ova of brown trout, Salmo trutta L., were exposed to all possible mixtures of Al (6000 nmol 11), Cu (80 nmol 1−1), Pb (50 nmol 1−1) and Zn (300 nmol 1 1). In a separate experiment, newly hatched brown trout yolk‐sac fry were exposed to Mn (1500 nmol 1−1), Fe (2500 nmol 1 1), Ni (200 nmol 1−1) or Cd (4 nmol 1 1), separately, and in mixtures with either Al or Cu. Both experiments were conducted in flowing, artificial softwater media nominally at pH 5.6 [Ca] 20 μmol 1 1 and 10° C.Mortalities were high in fry subjected to treatments which contained both Al and Cu (31–72%), and to the Cu + Fe treatment (78%) compared with those from the other trace metal mixtures (0–22%). In all the treatments tested, fry exposed to trace metal mixtures containing Al and/or Cu had reduced whole body Ca, Na and K content, and seriously impaired skeletal calcification. Whole body Mg content was variable. In trace metal mixtures which contained Cu but not Al, the effects on fry survival and whole body mineral content were in general more deleterious than the corresponding mixtures but with Al present rather than Cu. The presence of Pb and/or Zn in mixtures with Al and/or Cu had a slight ameliorative effect in terms both of fry survival and whole body mineral content.
Effects of development, temperature and salinity on metabolism in eggs and yolk‐sac larvae of milkfish, Chanos chanos (Forsskål)
Authors: Walsh W. A. , Swanson C. , Lee C.‐S. 
Published: January 2006

Oxygen uptake rates and yolk‐inclusive dry weiGhts were measured during the egg and yolk‐sac larval stages of milkfish, Chanos chanos (Forsskal). Oxygen uptake by eggs and yolk‐sac larvae was measured to assess the effects of four salinities (20,25,30,35 ppt) at 28°C. The effects of three temperatures (23,28,33°C) on oxygen uptake by yolk‐sac larvae were determined at a salinity of 35 ppt. Dry weights were measured throughout embryonic development at 28°C and the yolk‐sac stage at 23.28 and 33°C.Oxygen uptake rates of eggs increased more than fivefold during embryogenesis (0.07±0.03 to 0.40 ± 03 μl O2 egg −1 h −1;blastula to prehatch stage). Larval oxygen uptake did not change with age but was affected by rearing temperature (0.33 ± 0.08, 0.44 ± 0.07 and 0.63 ± 0.13 μl O2 larva −1 h−1 at 23, 28 and 33°C, respectively; Q10= 1.93). Acute temperature changes from 28 to 33°C caused significant increases in oxygen uptake by embryos (Q 10= 1.69–3.58) and yolk‐sac larvae (Q 10=2.55). Salinity did not affect metabolic rates.Dry weight of eggs incubated at 28°C decreased 13% from fertilization to hatching. Incubation temperatures from 23–33°C did not affect dry weights at hatching. Rearing temperatures significantly affected the rate of larval yolk absorption (Q 10= 2.25).