bluuebunny/crossref_metadata_2025_split huggingface dataset:
Osmotic stress and mortality in adult American shad during transfer from saltwater to freshwater
Authors: Leggett William C. , O'Boyule Robert N. 
Published: January 2006

Thirty‐five adult American shad (Alosa sapidissima) were moved quickly (2.5 h) from saltwater to freshwater. Changes in the levels of osmotically active blood constituents and of mortality were observed during and after the transfer. These were compared with levels of corresponding constituents and of mortality in 20 shad maintained in saltwater under similar conditions and to 44 shad sampled immediately after capture in saltwater and in freshwater (40 km from the saltwater‐freshwater interface). Sodium and chloride levels in theblood of the transferred group declined sharply during and after transfer. Calcium, glucose and lactic acid levels increased, and potassium and magnesium levels remained stable. Transferred shad experienced heavy mortality beginning 5 h after the initial reduction in salinity associated with movement into freshwater. No mortality was experienced in the group held in saltwater.It was concluded that the extensive meandering exhibited by adult shad at the upper limit of the salt‐freshwater interface during their spring migration in the Connecticut River is a behavioural response designed to slow the transition from the saltwater to the freshwater environment, thereby minimizing the physiological stress involved and/or allowing full recovery from this stress before proceeding upriver.
The basis of food selection in some estuarine fishes. Eels, Anguilla anguilla (L.), whiting, Merlangius merlangus (L.), sprat, Sprattus sprattus (L.) and stickleback, Gasterosteus aculeatus L.
Authors: Moore J. W. , Moore I. A. 
Published: January 2006

The factors influencing the selection of food by eels, Anguilla anguilla, whiting, Merlanglus merlangius, sprat, Sprattus sprattus, and stickleback, Gasterosteus aculeatus have been investigated by analysing collections made in the Severn Estuary for 1 year. Non–migratory (yellow) eels measuring from 19–5–56–5 cm in length fed mainly on either the decapod Crangon vulgaris or on the mysid Neomysis integer during the warmer months but ceased to feed in the winter. Whiting measuring between 2–5 and 15 cm fed almost exclusively on C. vulgaris, N. integer and the sand goby, Pomatoschistus minutus. Sprats fed chiefly on either the arnphipod Gammarus salinus or N. integer. Sticklebacks seldom contained any food in their stomachs despite the presence of large quantities of suitable prey and the high level of hunting efficiency. Gammarus salinus, although normally abundant in the environment, was usually ingested in disproportionately small quantities by all fishes except sprats reflecting its concealment among floating weeds and a selection against small (less than 1 cm) organisms. Because of the limitations of size and the unusually efficient escape reaction of larger animals, only young representatives of Crangon vulgaris were captured. The isopod Eurydice pulchra was rarely eaten by any of the fishes even though it was common in the environment. Burrowing polychaetes, mainly Nereis diversicolor, were never utilized possibly due to the difficulty involved in removing these organisms from the substrate. Neomysis integer was the most frequently consumed organism. Although the average length of prey ingested by the whitings increased with the size of fish, this was not the case for the other species. The proportion of non–feeding eels and the dry weight of stomach contents of this species depended on the temperature of the water but were not related to the availability of prey and tidal conditions whereas the feeding of whiting could not be related to any environmental parameter.
Studies on the ichthyo‐fauna in Plover Cove Reservoir, Hong Kong: I. Sequence of fish population changes
Authors: Man Hanson S. H. , Hodgkiss I. J. 
Published: January 2006

Gill‐net surveys were made weekly from May 1971 to April 1974 in Plover Cove Reservoir, Hong Kong and the results analysed to determine the fish species composition in the reservoir, the seasonal fluctuation of catches and the length frequency distribution of some major species.Over 20 species were represented in the fish fauna including almost all the naturally occurring species as well as the stocked species. Of the twenty species, some were collected regularly in gill‐net samples while others occurred rarely. Sarotherodon (Tilapia) mossam‐bicus (Peters) was the dominant species and contributed the main bulk of the catch. This species also showed distinct age groups in the reservoir and modal changes occurred seasonally. Thus, among the fish species studied only S. mossambicus showed a steady and progressive increase in abundance in the reservoir and the full development of this fish population with its wide range of feeding habits should be beneficial.
Approaches to the analysis of energetic costs of intraspecific competition for space by rainbow trout (Salmo gairdneri)
Authors: Li Hiram W. , Brocksen Robert W. 
Published: January 2006

Two approaches of estimating energy expended by rainbow trout (Salmo gairdneri) on density‐dependent activities were tested. Metabolic rates were obtained from growth experiments in laboratory systems. Increases in metabolic rates at higher population densities were attributed to three factors: (1) starvation, (2) increased levels of exercise by subdominant fish were forced to maintain stations in fast water due to saturation of territories of more dominant trout, (3) higher planes of excitation. It was observed that variance of energetic factors of routine metabolism, growth rate, consumption rate, and growth efficiency tended to increase with density. These responses seem to be a good indication of intraspecific competition. Little correlation was observed between density and average daily ration, or density and aggressive behaviour.Dominant trout, as a group grew faster, grew more efficiently, and contained greater lipid content than the rest of the population at each density. However, strictly defined, energetic advantages were not conferred on a ‘peck‐right’ basis. At higher densities, dominance conferred less benefits than was observed at lower population levels. Space limitation per se was not an influential factor affecting growth rates. Methods used to estimate density‐dependent energy costs are evaluated. Both methods give nearly identical estimates.
Effect of photoperiod on the incorporation of 3H‐thymidine into the gonads of Carassius auratus
Authors: Yadav M. , Ooi S. Diana 
Published: January 2006

Gldfish, Carassius auratus of varying sizes were conditioned in continuous light or darkness f or 10, 20 and 30 days and the incorporation of 3H‐thymidine into the gonads was investigated to attempt to develop a bioassay for fish gonadotropins.The 24‐hour gonadal 3H‐thymidine of 10‐day conditioned fish was significantly less at the dose level of 0.5 μCi 3H‐thymidine/fish compared to 1.0, 2.0 and 3.0 μCi/fish which gave gonadal activities not significantly different from each other. Thus, for all subsequent work the dose of 1.0 μCi/fish was used.Photoperiod of continuous light or darkness had little effect on fish weighing less than 11 g but in fish 11‐15 g conditioned for 20 days in darkness and fish greater than 16 g conditioned for 10 days in darkness, depression in gonadal 3H‐thymidine incorporation occurred. In fish 11‐15 g, prolonged conditioning for 30 days in darkness induced more gonadal activity than was observed at 20 days.The effect of injection of Channa striatus pituitary extract at doses of 1 mg/10 g body weight and 5 mg/10 g body weight induced a significant increase in 3H‐thymidine incorporation in the gonads over saline injected controls. The results suggest the potential of using photoperiod as a means of inducing regression of gonads of suitable fish in a bioassay of gonadotropins.
Acute Toxicity of water‐borne dimethylnitrosamine (DMN) to Fundulus heteroclitus (L.)
Authors: Ferraro Linda A. , Wolke Richard E. , Yevich Paul P. 
Published: January 2006

Acute (120h) toxicity of the water‐borne carcinogen, dimethylnitrosamine (DMN) to adult Fundulus heteroclitus (L.) at 20°C and 20.2%0 salinity in natural seawater was determined. The LC‐50 values were 8300 mg/1 at 24 h, 5500 mg/1 at 48 h, 4700 mg/1 at 72 h, 3300 mg/1 at 96 h and 2700 mg/1 at 120 h.Gross lesions consisted of peritoneal and cephalic ecchymoses. Microscopic lesions included necrosis and sloughing of the gastrointestinal mucosa, haemorrhage and necrosis of the liver, and necrosis of taste buds, with severity and incidence being a function of DMN concentration. Acute pathological effects of DMN on Fundulus heteroclitus conformed closely to those reported in other species exposed to this compound by respiratory, oral or parenteral route. DMN concentrations used in this experiment greatly exceeded those expected to be found under natural conditions, and this report is intended both to improve our understanding of DMN‐induced pathology in marine fishes and to provide further evidence of the consistency of acute lesions induced by DMN, regardless of test organism or mode of exposure.
Comparative observations on the growth rate and year class strength of roach Rutilus rutilus L. in two Cheshire lakes, England
Authors: Goldspink C. R. 
Published: January 2006

In this study some comparative data on the growth rate and year class composition of roach in two Cheshire meres (Rostherne and Tatton) are given. The populations are characterised by year class instability and high growth rates, both of which are most extreme in Tatton Mere. The growth of roach in Tatton Mere is the highest yet recorded from Britain.The concurrence of two (1969, 1973) strong year classes in both lakes, suggests that climate is an important factor which conditions year class strength. However, although there is some correlation between year class strength and the water temperature index (>14° C) the ultimate cause of year class variability remains obscure. There is no evidence to suggest that year class failure is due to parasitic infestation by Ligula intestinalis or to predation by perch upon roach fry. Year class failure may be due to the mortality of eggs related to the time of spawning. The observed difference in growth rate between the two populations may be attributed to a difference in density caused by the disparity of year class representation in Rostherne Mere and Tatton Mere. However, despite these differences, the net biomass achieved (36–39 kg ha−1) may be similar in both lakes. Superimposed on the effects of density an influence of temperature is noted.
Seasonal changes in reproductive function of the rainbow trout (Salmo gairdneri)
Authors: Whitehead C. , Bromage N. R. , Forster J. R. M. 
Published: January 2006

The sequential changes in serum oestradiol 17β (measured by specific radioimmunoassay), vitellogenin (measured by phosphoprotein phosphorus content) and total calcium (measured by fluorimetry) in male and female rainbow trout under a simulated natural photoperiod cycle were investigated. Resting levels of 130 pg/ml serum oestradiol in both male and female fish were found in April and May. In the female, levels reached a peak of 4800 pg/ml in October, and almost returned to resting levels just prior to spawning in mid‐January. No significant change from resting levels was seen in the male fish.In both male and female fish levels of 25 μg/ml serum phosphoprotein phosphorus and 10–14 mg % total serum calcium were found from April to July. Coincident with the rise in oestradiol 17β, in the females serum levels of phospho‐protein phosphorus and total calcium increased to 400 uβg/ml and 58 mg% respectively just prior to spawning. In the males no significant change in either of these values was observed throughout the cycle. These results strongly support the hypothesis that photoperiod is the major factor in the environmental control of reproductive activity in the rainbow trout.
Metabolic effects of partial pancreatectomy in the Northern pike, Esox Indus L.
Authors: Ince B. W. 
Published: January 2006

Metabolic effects of partial pancreatectomy (70%) after 1 month were studied in the Northern pike, Esox lucius L. Plasma protein and haematocrit levels were significantly reduced in the pancreatectomised fish when compared with sham‐operated controls. By contrast, however, blood glucose, plasma amino acid nitrogen and cholesterol levels remained unaltered.The tolerance to intra‐arterial glucose and amino acid loading was compared in pancreatectomised and control fish. Pancreatectomy resulted in a significantly impaired clearance of amino acids from the plasma whereas glucose tolerance was similar in both groups. Neither glucose nor ketones could be detected in the urine of pancreatectomised pike after 1 month. These data indicate that partial pancreatectomy does not cause the development of a diabetic state in this species over a 1 month period.
Distribution and development of rodlet cells in the gills and pseudobranch of the bass, Dicentrachus labrax (L)
Authors: Mattey D. L. , Morgan M. , Wright D. E. 
Published: January 2006

Rodlet cells in various stages of development were found in large numbers in the bass gill and pseudobranch. In the gill, rodlet cells were found in the epithelium at the base of the secondary lamellae and on the filament between adjacent lamellae, whilst in the pseudobranch they were found over the whole area of the secondary lamellae as well as in the filament epithelium.During early development, rodlet cells are characterised by their amorphous cell inclusions, prominent supranuclear Golgi complex and network of granular endoplasmic reticulum. Later, with formation of a fibrous border the arrangement of the cell organelles undergoes reorganisation; the endoplasmic reticulum becomes distended, numerous vesicles appear and the mitochondria aggregate in the apical region of the cell. One of the most striking features is the development of club‐shaped sacs containing electron dense cores, which are orientated towards the open apex of the cell.Various staining properties of rodlet cells for light and electron microscopy were compared with those of mucous cells found in the same tissues. Possible functions of the cell are discussed.
Analysis of catch data from 1968 to 1976 from nine fish landings in the Kenya waters of Lake Victoria
Authors: Benda R. S. 
Published: January 2006

Fish landing data collected by the Kenya regional fisheries officers from Homa Bay, Kaloka, Karungu, Marenga, Wichlum, Kendu Bay, Usenge, Dunga and Ngegu from 1968 to 1976 were statistically analysed to determine trends in the traditional fisherman's catch in the Kenya waters of Lake Victoria. Over the nine years a significant decline occurred for total catch and catches of Haplochromis spp., Tilapia spp. and Protopterus aethiopicus. Engraulcypris spp. catch increased significantly; while catches of Bagrus docmac and Clarias mossambicus fluctuated and no clearly defined trend emerged, although B. docmac catch seemed to be declining.Overall indications were that as the catch of traditionally preferred fish declined, Engraulicypris spp., B. docmac, C. mossambicus and recently introduced Lates niloticus were becoming more important to the total catch.
Agonistic behaviour of age 0, age 1 and non‐breeding adult Arctic grayling Thymallus arcticus (Pallas)
Authors: Kratt L. F. , Smith R. J. F. 
Published: January 2006

Age 0 Arctic grayling begin to show agonistic behaviour 3 weeks after emergence and are territorial by their fourth week. Age 1 fish are territorial throughout the summer feeding period. In adults, territoriality is restricted to larger males during the early spring breeding season while after the breeding season both smaller adult males and adult females also hold territories.In sub‐adults, larger fish and resident fish tend to win most fights. In adults, males usually win against females. In fights between adults of the same sex, larger and resident fish usually win.The lateral display becomes more important in the agonistic repertoire of Arctic grayling as they mature and the characteristic large dorsal fin develops. Arctic grayling appear to lack an appeasement display.
Restoration of glycogen from lactic acid in the anaerobic swimming muscle of plaice, Pleuronectes platessa L.
Authors: Batty R. S. , Wardle C. S. 
Published: January 2006

The conclusion from two in vivo experiments is that a significant proportion of the lactic acid, normally formed by glycolysis from glycogen and held in the muscle cells following exhausting exercise of the anaerobic swimming muscle of the teleost fish Pleuronectes platessa L, is converted by gluconeogenesis to form glycogen in the recovering muscle.In the first experiment a technique for measurement of [3H]glucose turnover in the plaice was developed and applied to measure turnover in resting and exhausted fish. It is concluded that insufficient glucose was moved through the circulation to account for the rate of glycogen formation observed in the recovering exhausted muscle.In the second experiment, an intramuscular injection of [14C]lactate to exhausted fish revealed a direct uptake of [14C]lactate by the recovering muscle cells, and the incorporation of substantial proportions of lactate into the restored glycogen. Simultaneous use of [3H]‐mannitol allowed measurement of the isotope distribution between extra‐ and intracellular spaces.
The haematological assessment of bacterial infection in rainbow trout, Salmo gairdneri Richardson
Authors: Barham W. T. , Smit G. L. , Schoonbee H. J. 
Published: January 2006

The pH, pCO2 and pO2 values for diseased fish did not differ significantly from those values for healthy fish, but fish treated with terramycin showed a highly significant rise in pCO2 with a corresponding fall in pO2. Haematocrit values, as well as haemoglobin and total plasma protein concentrations were significantly lower in diseased fish while treated fish showed a significant rise in total plasma protein. Glucose concentrations fell very significantly in diseased fish and showed a significant increase in treated fish.The plasma electrolytes, sodium, potassium and chloride, were significantly reduced in diseased fish and potassium levels also fell in treated fish. Diseased fish showed very significantly reduced erythrocyte counts. Of the three parameters MCV, MCH and MCHC, only the values for MCH in diseased fish differed significantly from those for healthy fish.
Survival and reproductive performance of the desert pupfish, Cyprinodon n. nevadensis (Eigenmann and Eigenmann), in acid waters
Authors: Lee R. M. , Gerking S. D. 
Published: January 2006

Desert pupfish, Cyprinodon n. nevadensis, were exposed to pH levels of 8·3 (control), 7·0, 6·5, 6·0, 5·5 and 5·0 to determine the effects of acidity on reproduction. Egg production was significantly reduced at every pH level tested below the control. Egg‐laying virtually ceased at pH 5·0, while egg viability was reduced to less than 50% of the control value at pH 6·5, when eggs were tested at the same pH at which they were laid. The 96 h LC50 for this species was pH 4·56, considerably below that for successful reproduction. Larvae were less tolerant to acid stress than were adults.Acclimation of reproductive performance to increased acid levels did not occur. Reproductive performance did not fully recover to control levels when the fish were placed in more favourable conditions after prolonged exposure to low pH.Reduction in the number and development of oocytes was observed in the ovaries of acid stressed fish resulting in the decreased reproductive potential.
A study of the histology and morphology of the digestive tract of the common eel (Anguilla anguilla)
Authors: Clarke A. J. , Witcomb D. M. 
Published: January 2006

The anatomy and morphology of the digestive tract of the eel was examined using light and scanning electron microscopy. The oeosphagus showed complex longitudinal folding; stratified epithelium, columnar epithelium and goblet cells striated muscle fibres formed the thick muscular coat. The pneumatic duct entered the oesophagus anterior to the oesophagastric junction. The Y shaped stomach showed large well developed folds which decreased in size and number towards the pyloric sphincter. Columnar epithelium and gastric gland cells were present, the latter being absent from the pyloric region.The intestine had a heavily thickened anterior region, signs of convulation were noted prior to the ileorectal valve. Intestinal folding showed a complex reticulate pattern with columnar epithelium and goblet cells present. The mucopolysaccharides were studied in the goblet and columnar cells throughout the regions of the gut. Lymphocytes and eosinophilic type cells were found in the connective tissue of the mucosa throughout the gut. The pancreas was a compact organ with few Islets of Langerhans, beta cells were peripherally situated and alpha cells centrally. The unilobular liver acted as a storage organ for oil and glycogen.
Effects of temperature and photoperiod on ovarian recrudescence in the cyprinid fish Mirogrex terrae‐sanctae
Authors: Yaron Z. , Cocos M. , Salzer H. 
Published: January 2006

Mirogrex terrae‐sanctae is a commercial, sardine‐like cyprinid fish in the Sea of Galilee. The fish spawns from December to the end of March. Females collected at the quiescent phase of the cycle (June) were exposed to four combinations of photoperiod and temperature for 3 months. The highest GSI (2.44 ± 0.22) was found in females exposed to simulated winter conditions (16°C, 9L) while the lowest GSI (0.65 ± 0.04) was found in fish exposed to simulated summer conditions (27°C, 14L). The GSI of fish maintained at the unnatural combination of 16°C, 14L (1.30 ± 0.09) did not differ from that of fish maintained at the other unnatural combination of 27°C, 9L (1.07 ± 0.11). However, histological examinations revealed that vitellogenic oocytes were present only in fish maintained at low temperature regimes, which implies that the growth of the ovarian mass in the 27°C, 9L group was due mainly to oogonial proliferation and that vitellogenesis was inhibited in Mirogrex at a high temperature.Both protein and calcium concentrations increased in the serum of fish following injections of oestradiol‐17β. The increase of calcium was evident only in the non‐filtrable (bound) fraction, suggesting that the total serum calcium above 13 mg% could be used as an indirect parameter for circulating vitelloprotein.Fish collected at the quiescent phase were injected with oestradiol (50 μg/fish c. 15 g body weight) and subsequently transferred to tanks maintained at either 12°, 20° or 27°C. The total serum calcium increased to 23.0 ± 1.75 mg% in the fish maintained for 8 days at 20°C. This was significantly higher than the concentration of calcium in the serum of fish maintained at either 12°C (7.8 ± 0.52) or 27°C(l1.8 ± 0.77). This implies that the temperature may affect ovarian recrudescence by modulating the response of the liver to oestrogen, allowing the oestrogen‐induced vitellogenesis to be relatively high in the cool environment during winter.
Hydrodynamics of suction feeding of fish in motion
Authors: Weihs D. 
Published: January 2006

Forward motion was shown to increase the efficiency of suction feeding by causing the ingested volume to be predominantly in front of the fish, instead of being a sphere centred on the fish mouth. This increases the distance from which a prey, located in front of the predator, can be ingested by suction.A general hydrodynamic model of the external effects of the suction process is presented, showing that this is dependent upon a single non‐dimensional parameter, the ratio of a characteristic mouth dimension, divided by the forward swimming speed and the suction time. Data for large‐mouth bass, Micropterus salmoides show that the observed average forward velocity while feeding, of 3.1 body length/s, serves to increase the ingestion range by more than 60% over suction while not moving.