bluuebunny/crossref_metadata_2025 huggingface dataset:
Salinity adaptation in the snakehead, Ophiocephalus maculatus Lacépède: changes in oxygen consumption, branchial Na+‐K+‐ATPase and body composition
Authors: Woo N. Y. S. , Tong W. C. M.
Published: January 2006

Snakeheads were adapted to fresh water (1 mOsm kg−1), 25% sea water (230 mOsm kg−1), 33% sea water (320 mOsm kg−1) and 40% sea water (380 mOsm kg−1) for 20 days. Exposure to salt water resulted in tissue dehydration, elevations of plasma osmolality, Na+, Mg2+, Cl−and protein concentrations and stimulation of branchial Na+‐K+‐ATPase activity. These changes were accompanied by concomitant decline of the hepatosomatic index and liver glycogen concentration. The routine rate of oxygen consumption was increased in snake‐heads adapted to 33% sea water. These data were taken to indicate a stressful effect of salinity to the snakehead despite documentation of its ability to penetrate into brackish waters.
Ontogenesis of osmotic regulation in the striped mullet, Mugil cephalus L.
Authors: Nordlie F. G. , Szelistowski W. A. , Nordlie W. C.
Published: January 2006

The osmoregulatory capabilities of juvenile striped mullet, Mugil cephalus L., of three size‐groups (20–29, 30–39 and 40–9 mm s.l.) were compared in a series of six salinities ranging from fresh water to full sea water. The two smaller size‐groups were able to tolerate instantaneous transfer from the brackish water in which captured, to all salinities but fresh water, while the 40–69 mm group were tolerant of instantaneous transfer to all experimental salinities. At high environmental salinities, the osmotic regulatory capabilities improved with growth in size to an apparently definitive condition in fish of 40–69 mm s.l. The smallest of these individuals were estimated to be about 7.5 months old. The osmotic regulatory capability in waters of low salinity had reached a definitive state with the development of tolerance to such salinities. The ontogenetic pattern for Mugil cephalus is virtually identical to that of the Atlantic salmon, Salmo salar.
Ascorbic acid status of mullet, Mugil cephalus Linn., exposed to cadmium
Authors: Thomas P. , Bally M. , Neff J. M.
Published: January 2006

The effects of acute and chronic cadmium exposures on ascorbic acid concentrations and cadmium accumulation in the tissues of juvenile mullet, Mugil cephalus, are described. Hepatic ascorbic acid reserves were maintained in untreated mullet fed a diet containing ascorbate, but decreased 60% in individuals exposed to 10 mg Cd 1‐1 for six weeks. Ascorbic acid depletion was accompanied by a massive accumulation of cadmium in the liver. Similar changes were found in gill tissue. In contrast, ascorbic acid concentrations were largely unaffected in kidney tissue which had a limited capacity to accumulate the metal. There were marked fluctuations of ascorbic acid levels in the brain. Only small amounts of cadmium were accumulated by this tissue. These results indicate that in mullet liver, gill and brain ascorbic acid stores may be depleted during chronic cadmium poisoning.
Mebendazole/trichlorfon combination: a new anthelmintic for removing monogenetic trematodes from fish
Authors: Goven Beverly A. , Amend Donald F.
Published: January 2006

Mebendazole, trichlorfon, and a combination of these two drugs were evaluated for anthelmintic properties against the external monogenetic trematodes of fish, Gyrodactylus elegans and Dactylogyrus vastator. Mebendazole effectively removed G. elegans after a 24‐h. exposure to 0·01 mg l‐1, but it had no effect on D. vastator up to 2·0 mg l‐1. Trichlorfon was 95% effective on D. vastator between 0·4 and 1·6 mg l‐1 after a 24‐h exposure, but it had no effect on G. elegans up to 2·0 mg l‐1. A combination of mebendazole at 0·4 mg l‐1 and trichlorfon at 1·8mgl‐1 was 100% effective on both parasites. Trichlorfon appeared to inhibit the action of mebendazole on G. elegans, but mebendazole had no apparent inhibition on the action of trichlorfon to D. vastator. The minimum effective exposure time was 24 h and shorter exposure times, even at high dose levels, were not effective. The combination had no apparent toxic effect on fish, except possibly catfish, and field tests in various geographical areas of the United States showed that the combination was effective in all cases.
The effect of ration and temperature on the growth of the three‐spined stickleback, Gasterosteus aculeatus L.
Authors: Allen J. R. M. , Wootton R. J.
Published: January 2006

The effect of ration on the growth of the three‐spined stickleback, Gasterosteus aculeatus, was studied over the temperature range 3·19°C, which corresponded to the range in their natural habitat. With an ad lib ration, the specific growth rate increased with temperature. The relationship between specific growth rate and ration at a given temperature was curvilinear. Regression models were used to predict the maximum, optimum and maintenance rations at each temperature. Whereas maximum ration increased rapidly with temperature, the optimum and maintenance rations were relatively insensitive to temperature. A regression model was used to describe the overall relationship between specific growth rate and ration, temperature and body weight. This model predicted that at low rations, growth rate decreased with temperature, whereas at high rations, growth rate increased slightly with temperature. The gross growth efficiency increased rapidly with rations above maintenance ration up to a maximum at the optimum ration and declined at higher rations. The maximum gross growth efficiencies were at high temperatures and rations about half of the maximum ration. The maximum net growth efficiencies occurred at relatively low temperature and at rations just above maintenance.
The variability in the catches of charr, Salvelinus alpinus L., and perch, Perca fluviatilis L., from multi‐mesh gill nets
Authors: Craig J. F. , Fletcher J. M.
Published: January 2006

Multi‐mesh gill nets set at Rawlinson's Nab in the south basin of Windermere for 24 months from 1979 to 1981 caught predominantly charr and perch. Nets set parallel to the shore caught significantly fewer fish than those set perpendicular to the shore. Variability in the mean catches of perch increased from winter to summer when the size of the catches also increased. Charr were mostly caught from November until February. Estimates of variance associated with the geometric mean catch of a single net (set perpendicular to the shore) were calculated for the periods winter for the charr and winter, summer, spring and autumn for the perch. These variances were used to calculate 95 and 99% C.L. of the geometric mean. For limits to be below half or twice the geometric mean, 12 nets would have to be used for charr during winter. For perch the number of nets needed would be six in winter, 20 in spring and autumn and 40 in summer. It is concluded that the nets are of little value in assessing changes in stock abundance.
A note on the occurrence of the digenetic trematode Sphaerostoma bramae (Müller) in the intestine of the European eel, Anguilla anguilla (L.)
Authors: Lacey S. M. , Williams I. C. , Carpenter A. C.
Published: January 2006

The allocreadiid digenean Sphaerostoma bramae (Müller) was found in three of 602 eels, Anguilla anguilla (L.), caught over a period of 25 months from drains and rivers in the lower River Trent drainage area. Eleven, 15 and 32 specimens of S. bramae were found in the posterior 40% of the respective host's intestine. Concurrent infestations with Proteocephalus macrocephalus, Acanthocephalus clavula and Rhaphidascaris acus were observed. The results are discussed in relation to the helminthology and ecology of the eel.
In vitro study on the interactive effects of heavy metals on catalase activity of Sarotherodon mossambicus (Peters)
Authors: Singh Sukhdev M. , Sivalingam P. M.
Published: January 2006

The in vitro effects of individual heavy metal ions as well as their combinations on catalase activity were investigated. Copper was found to be the strongest inhibitor of catalase activity followed by mercury, iron, chromium and cadmium. Copper toxicity on catalase activity was reduced in the presence of all the other metal ions. However, the addition of cadmium, chromium, iron, manganese, lead to mercury and cadmium, iron, manganese, nickel, lead, zinc to chromium increased their inhibitory effects on catalase activity.
Seasonal variations in biochemical composition and energy content of liver, gonad and muscle of mature and immature cod, Gadus morhua (L.) from Balsfjorden, northern Norway
Authors: Eliassen Jens‐Eric , Vahl Ola
Published: January 2006

Seasonal energy changes in mature and immature cod of the same size were studied. For most of the year, the variations in energy content in the tissues of both mature and immature cod are similar. In the period from October to January, the fish accumulate energy. From January until spawning in early April there is a fall in the total energy content. The growth of gonads from January until spawning can explain about one‐third of the energy decrease in liver and muscle.
Optimization of assay conditions for, and the selected tissue distribution of, alanine aminotransferase and aspartate aminotransferase of English sole, Parophrys vetulus Girard
Authors: Casillas E. , Sundquist J. , Ames W. E.
Published: January 2006

Optimization of assay conditions for serum alanine aminotransferase (ALAT, GPT) and aspartate aminotransferase (ASAT, GOT) are described for English sole, Parophrys vetulus. Although most conditions for measurement of these fish enzymes parallel conditions in mammals, the optimal pH is lower for both these enzymes. Liver represents a potentially large source of ASAT activity, potential sources for ALAT activity are liver and kidney. As in mammals, the use of these enzymes as indicators of fish liver and kidney dysfunction may be warranted.
A note on catches of basking sharks, Cetorhinus maximus (Gunnerus), off Norway and their relation to possible migration paths
Authors: Stott F. C.
Published: January 2006

The distribution and the times of the main catches of the basking shark, Cetorhinus, maximus (Gunnerus), in the commercial fishery off the coast of Norway during the seasons of 1971, 1972 and 1973 are given and analysed. No easily recognized regularities have been identified from season to season so that it is evident that there is no pattern of migration towards the Norwegian coast comparable to that of the bluefin tuna, Thunnus thynnus L., which once provided a substantial fishery in the same area.
The effect of captivity on the immune response of the killifish, Fundulus heteroclitus L.
Authors: Miller N. W. , Tripp M. R.
Published: January 2006

Fundulus heteroclitus maintained under laboratory for more than four weeks showed a significantly lower immunocytoadherence (rosette) response to thymus‐dependent antigens (SRBC and DNP‐BSA) than newly captured fish. There was no comparable effect on scale allograft rejection nor in the response to a thymus‐independent antigen (DNP‐Ficoll) as measured by the rosette response. This suggests that captivity has a differential effect on a sub‐population of lymphocytes analogous to the T‐helper cells of mammals.
Observations on movement patterns of Tilapia spp. in Nyanza Gulf, Lake Victoria, East Africa
Authors: Rinne J. N. , Wanjala B.
Published: January 2006

Movement of the introduced Tilupiu spp. in the Nyanza Gulf of Lake Victoria is largely random, however, mobility has a strong correlation with dry and rainy seasons. The seasonal pattern of movement may be attributed to the response of the species to spawning and feeding drives and favourable living areas. Tilupia movements were typically short (< 1 km) and there were no systematic shifts in centres of gravity of populations.
Food and feeding habits of the larvivorous fish Aplocheilus lineatus (Cuv. & Val.) in its natural habitat
Authors: Jacob Sheila Susan , Nair N. Balakrishnan
Published: January 2006

Results are presented of a study of the food and feeding habits of Aplocheilus lineatus under natural conditions and the manner in which dietary preferences are influenced by the habitat/environment, seasons and stage of maturity of the fish is explained, based on data from montly random samples collected for a year. A qualitative assessment of the diet reveals that it is not confined to a varied range of aquatic fauna, but also encompasses allochthonous fauna. Quantitative and qualitative analyses of the diet indicate its feeding habit which does not alter with size or seasonal changes. The range of prey consumed does not differ radically, qualitatively, as a function of size, but quantitatively exhibits five levels of discrimination and differential exploitation related mainly to prey size. Seasonal fluctuations in feeding are more qualitative than quantitative and seem dependent on the occurrence of food organisms. The lack of correlation between breeding and feeding is linked to extent of the development of the gonad in the body cavity. In conclusion, the potential of the fish as an effective biological control agent of mosquito larvae is indicated by the fact that dipteran larvae are a preferred item of its diet in all size groups.
Administration of cortisol to brown trout, Salmo trutta L., and its effects on the susceptibility to Saprolegnia infection and furunculosis
Authors: Pickering A. D. , Duston J.
Published: January 2006

Oral administration and intraperitoneal implantation can be used to administer cortisol to the brown trout. Both techniques produce a dose‐dependent increase in plasma cortisol concentration and the experimental procedures reduce the stress response in control fish to a minimum level. The plasma levels of the steroid are within the physiological range for the fish and the time of the response to acute oral administration is similar to that for such stresses as crowding, pollution and confinement. The evidence strongly indicates that elevated cortisol levels can significantly increase the susceptibility of salmonid fish to a wide range of infectious diseases including furunculosis and fungal infection. The present study has shown that this can occur at cortisol levels within the normal physiological range of the fish.
Post‐ stocking movements and recapture of hatchery‐reared trout released into flowing waters—effect of prior acclimation to flow
Authors: Cresswell R. C. , Williams R.
Published: January 2006

Hatchery‐reared brown trout, Salmo trutta, (f.l., 16–27 cm) were stocked into the Afon Clettwr, Afon Western Cleddau and Afon Dysynni, Wales. The effects of (a) retaining fish caged in the river for 24 h before release, and (b) a period of acclimation to flowing water (up to 0.24 m s−1) in tanks prior to stocking were investigated. Data on percentage recapture and post‐stocking movements were obtained from trapping, electrofishing and tag returns. In‐stream acclimation resulted in a higher percentage recapture and a more limited dispersion of the fish stocked under low river flow conditions, but had no effect on trout stocked into a river where higher water velocities were experienced. Acclimation, in tanks, to a flow of 0.1 ms−1 for 14 days led to higher percentage recaptures, whereas acclimation for only 2 days resulted in fewer returns than for unacclimated fish. No differences in fish distribution within the rivers could be attributed to these acclimation procedures.
Bioassay of insulin activity of pancreatic tissue in active and aestivated African lungfish, Protopterus annectens (Owen)
Authors: El Hakeem O. H. , Babiker M. M.
Published: January 2006

The insulin activity of the pancreatic tissues of free‐swimming and aestivated African lungfish, P. annectens (Owen), was bioassayed against standard insulin in rabbits. The hepatic glycogen content and plasma glucose concentration in free‐swimming and aestivated lungfish were also estimated. The liver glycogen content was 64·47 ± 6·32 and 7·19 ± 2·68 mgg−1 net wt and the plasma glucose concentration was 37·62 ± 4·22 and 6·39 ± 1·29% in free‐swimming and aestivated lungfish, respectively.

Extracts of pancreatic tissue of the lungfish produced a dose‐dependent decrease in the plasma glucose concentration in rabbits. The magnitude of the decrease in plasma glucose concentration produced by extracts from aestivated specimens was significantly smaller (about 26%) compared to that produced by pancreatic extracts from free‐swimming active lungfish (about 37%). The insulin activity of the pancreatic tissue was 0·82 ± 0·02 and 1·27 ± 0·25 iu mg−1 dry pancreatic tissue weight in aestivated and free‐swimming lungfish, respectively.
Observations on the food of juvenile Atlantic salmon, Salmo salar L, reared in a Scottish hill loch
Authors: Morrison B. R. S.
Published: January 2006

An analysis of the stomach contents of 0+ and 1 + Atlantic salmon parr, Salmo salar, introduced into a Scottish hill loch showed that benthos, plankton, and surface organisms were all taken. Molluscs comprised a relatively small proportion of the food material, probably because they are less active than other animal groups. The most abundant plankter was Daphnia hyalina. Cyclops spp. were scarce and no Diaptomus spp. were present in the stomachs despite their abundance in the loch plankton. Laboratory experiments indicated that copepods were difficult to capture and that D. hyalina was the organism most frequently selected, even when larger individuals of this species were removed from the environment. Differences between the results from the Scottish loch and similar work in Wales, Sweden and Canada are discussed.
Pathology of lindane poisoning and of hypoxia in the brown trout, Salmo trutta L.
Authors: Drewett N. , Abel P. D.
Published: January 2006

A comparative study of the signs of lindane poisoning and of hypoxia in trout, Salmo trutta L., showed that the symptoms of both causes of death are similar. The rapid fading of gill colour within 2 h of death is characteristic of both treatments and distinguishes these from other causes of death. Vascular congestion and cellular damage of the liver is common to both treatments. The causes of death may be distinguished by the behaviour of the fish before death and by study of their effects on the gills. Hypoxic fish showed increased ventilatory activity, but other activity decreased. Exposure to lethal levels of lindane caused hyperactivity, convulsions, ataxia and intermittent paralysis. Although gill damage in both cases was slight it was distinctive. Lindane caused disarray of the secondary lamellae, and exposure to low dissolved oxygen levels caused breaks in the lamellar epithelium. This was only clearly visible under electron microscopical examination.
Some aspects of osmoregulation in a stenohaline freshwater catfish, Heteropneustes fossilis (Bloch), in different salinities
Authors: Goswami S. V. , Parwez I. , Sundararaj B. I.
Published: January 2006

Transfer of the catfish, Heteropneustes fossilis, to 10% sea water (101 mosmol l−1) or to 0·4% NaCl (140 mosmol l−1) does not evoke any change in plasma osmolarity from the normal freshwater values. There is, however, a reduction in urine flow rate (UFR) and increase in urine osmolarity without any change in the rate of osmolar clearance. In isosmotic (25% sea water or 0·7% NaCl) and in hyperosmotic (30% sea water or 1·1% NaCl) media there is a significant increase in plasma osmolarity accompanied by marked reduction in glomerular filtration rate (GFR), UFR and free water clearance. The results suggest that the catfish cannot effectively osmoregulate in isosmotic or hyperosmotic media and that the inability of the renal tubules to increase reabsorption of water and to reduce free water clearance may account for the restricted range of salinity tolerance of this catfish. Also, in the hyperosmotic media, plasma levels of cortisol are lowered while in the proximal pars distalis the corticotrophs appear active, suggesting increased utilization and clearance of cortisol. Prolactin‐secreting cells, however, are degranulated and chromophobic in catfish maintained in hyperosmotic environment.
Biometrical analysis of Chondrostoma polylepis × Rutilus arcasi natural hybrids (Osteichthyes—Cypriniformes—Cyprinidae)
Authors: Collares‐Pereira M. J. , Coelho M. M.
Published: January 2006

The biometrical analysis of 95 natural hybrids of Chondrostoma polylepis and Rutilus arcasi is presented and discussed. The authors confirmed their existence in the Douro basin and, based on these data, they try to explain their non‐accidental character. The possibility of introgression, and other aspects of hybridization are analysed in an attempt to explain the variability observed.
Gill morphology in the zebrafish, Brachydanio rerio (Hamilton‐ Buchanan)
Authors: Karlsson L.
Published: January 2006

A light and electron microscopic study of the gills of the zebrafish, Brachydanio rerio, were made to serve as a morphological basis for future investigations. It was found that for fixation of B. rerio gills, a mixture of 1·5% gluturaldehyde and 1·5% paraformaldehyde gives a mucus‐free surface. Morphometric measurements of structural components of the gill secondary lamellae were made. Observations at SEM were correlated with those made at TEM. The different cell types in the branchial epithelium were characterized. Chloride cells were mainly located in the interlamellar regions and on the afferent side of the primary lamellae. Two morphologically different chloride cells were seen. The first type communicates with the external environment through a reservoir‐like lumen, which is normally absent in freshwater fishes. The second type of chloride cell has more direct contact with the ambient water, resembling chloride cells from other freshwater fishes. Another cell type with features similar to those of the rodlet cell was frequently observed. This cell is interposed between other types of cells in the epithelium, and sometimes junctional complexes were present between the rodlet cell and surrounding cells.
Seasonal changes in serum thyroid hormone levels of the feral brown bullhead,Ictalurus nebulosusLesueur
Authors: Burke M. , Leatherland J. F.
Published: January 2006

Seasonal changes in serum L‐thyroxine (T4) and triiodo‐L‐thyronine (T3) concentrations were measured in a feral population of brown bullheads,Ictalurus nebulosus. Serum T4 was elevated in mid April concomitant with the onset of gonadal recrudescence and the increase in ambient temperatures from the winter level. Thereafter, serum T4 levels were constant throughout the late spring and summer (except for a significant lowering in levels associated with the spawning and early postspawning period), declining to a low overwintering level by mid December. Serum T3 levels increased in April, and apart from a significant decrease in July associated with the postspawning period, rose progressively until August, after which levels declined progressively to reach overwintering levels again by mid December. Between mid April and mid May serum T4/T3 ratios fell from the high values found in fish during the winter months. Apart from variations associated with the fluctuations of T4 and T3 concentrations in the spawning and early postspawning periods, serum T4/T3 ratios remained at a low level throughout the summer and early autumn months, and rose again in October to the overwintering levels. The circannual cycles are discussed in relation to the possible role of the thyroid hormone in gonadal maturation and metabolism in this species.
The autumn and spring emigrations of juvenile Atlantic salmon, Salmo salar L., from the Girnock Burn, Aberdeenshire, Scotland: environmental release of migration
Authors: Youngson A. F. , Buck R. J. G. , Simpson T. H. , Hay D. W.
Published: January 2006

Peaks in the emigratory activity of sexually immature, juvenile Atlantic salmon, Salmo salar, occur in autumn and early winter and in spring at the Girnock Burn in Aberdeenshire. Stream temperature is apparently without effect on the release of potentially emigrant fish from the stream. Migrants tend to leave the stream when stream discharge rate is elevated. Whereas downstream movements in autumn and the earlier part of the spring are made almost invariably when the stream's discharge rate is higher than the seasonal norm, later in spring they often occur when discharge rates are lower than the seasonal norm and when no apparent increase in absolute stream discharge rate has occurred. Emigration is depressed in the lunar quarter centred on the full moon. The nature of the relationship between the autumn and spring emigrations is discussed.
Some potentials and limits of the leucocrit test as a fish health assessment method
Authors: Wedemeyer G. A. , Gould R. W. , Yasutake W. T.
Published: January 2006

The sensitivity of the leucocrit as a stress tolerance and fish health assessment method was evaluated by subjecting juvenile coho salmon, Oncorhynchus kisutch, or steelhead trout, Salmo gairdneri, to standardized crowding, handling, temperature and disease challenges. The leucocrit was a sensitive indicator of the physiological stress resulting from crowding at population densities of 0·2–0·4 kg l−1, and to the stress of handling and to temperature changes. It was relatively insensitive to physiological sampling procedures which supports its continued development as a stress assessment method.

In the case of fish diseases, subclinical or active Renibacterium salmoninarum and Yersinia ruckeri infections had essentially no effect on leucocrit values. In contrast, active Aeromonas salmonicida infections significantly depressed the leucocrit. However, no change was seen during the subclinical (incubation) phase prior to the development of an epizootic. Thus, the potential of the leucocrit as a fish health assessment method appears limited.
A cytochemical, light and electron microscopical study of the leucocytes of the adult river lamprey, Lampetra fluviatilis (L. Gray)
Authors: Page M. , Rowley A. F.
Published: January 2006

The morphological features of the leucocytes from the blood of the river lamprey, Lampetra fluvimilis, were studied using light and electron microscopy. Four cell types were identified, namely granulocytes, lymphocytes, monocytes and thrombocytes. Enzyme cytochemical tests were also performed for the detection of acid phosphatase, β‐glucuronidase and peroxidase. All the leucocyte types were positive for acid phosphatase and β‐glucuronidase, to a variable extent, with the greatest activity seen in the granulocytes. None of the leucocyte types however, contained any peroxidase activity.

Only one type of granulocyte was found and this appears to be analogous to the mammalian neutrophil/heterophil. Characteristically, it has a cytoplasm containing a large number of morphologically heterogeneous granules (0.07–0.40 um in diameter). It is suggested that these granules, rather than belonging to several subpopulations, are in fact part of a single maturation series.

The results of this study show that precise identification of lamprey leucocytes can only be achieved using a combination of ultrastructural and cytochemical techniques.
Viability of catfish (Clarias macrocephalus, Gunther) eggs fertilized at varying post‐ovulation times
Authors: Mollah M. F. A. , Tan E. S. P.
Published: January 2006

HCG‐induced (dose: 2 iug−1 body weight) ovulated eggs of catfish (Clarias macrocephalus) remained viable for artificial fertilization up to 10 h post‐ovulation without apparent significant loss in fertility. At 12 h post‐ovulation viability decreased significantly, showing little or no hatching at 20 h. A limit of 10 h between ovulation and egg‐stripping was suggested for this species at an ambient temperature of 26–31° C.
Interference of o,p'DDD with interrenal function and cortisol metabolism in Sarotherodon aureus (Steindachner)
Authors: Ilan Z. , Yaron Z.
Published: January 2006

The purpose of this study was to investigate possible effects of organochlorine residues on cortisol balance in a freshwater fish. The combined stress of netting, handling and blood sampling in Sarotherodon aureus normally results in a twofold increase of circulating cortisol, within 30–60 min. Fish treated with o,p'DDD (50 mg kg−1) had higher resting level of cortisol than before treatment (155.8±12.7 v. 86.9± 11.2 ngmh−1; n=16). No further increase in cortisol level occurred in these fish after exposure to stress; this inability to respond was maintained for more than 120 days. A recovery of the response to ACTH by superfused interrenal tissue from the treated fish was observed 255 days after treatment. Successive blood sampling of o,p'DDD‐treated fish, injected intracardially with labelled cortisol, have shown that the half‐life of the steroid in the circulation is prolonged by 370% compared with controls. The hepatic metabolism of cortisol was studied by incubating liver slices with the labelled hormone. Hepatic tissue from o,p'DDD‐treated fish metabolized cortisol slower than livers from controls. The high resting level of cortisol in plasma of fish treated with o,p'DDD may be attributed to the retarded metabolism of the steroid by the liver. The lack of augmented cortisol levels in response to stress is attributed to the interference of the organochlorine with the response of the interrenal tissue to the stress‐induced surge of endogenous ACTH.
Non‐specific carboxylic esterase activity in the digestive tract of the perch, Perca fluviatilis L.
Authors: Hirji K. N. , Courtney W. A. M.
Published: January 2006

The distribution of non‐specific carboxylic esterases (Ec 3.1.1) in the digestive tract of perch, Perca fluviatilis L., was investigated histochemically using 1‐naphthyl acetate as the substrate. Strong enzymatic activity was present in the gastric glands and surface cells of the stomach, intestinal mucosa of the pyloric caeca, upper and middle intestine, pancreas (exocrine cells) and liver. The enzymatic activity in the lower intestine and rectum was weak. The activity was not demonstrated in the oesophagus or pyloric sphincter. In the intestine, the activity was localized in the columnar cells especially in the supranuclear cytoplasm. The enzymatic activity demonstrated in the digestive tract of perch using 1 ‐naphthyl acetate represents combined esterolytic and lipoproteolytic activity.
Yield per recruit of the Tambaqui, Colossoma macropomum Cuvier, in the Amazonas State, Brazil
Authors: Petrere M.
Published: January 2006

The tambaqui, Colossoma macropomum, is the most important fish landed at Manaus by the fishery in the Amazonas State, Brazil. Population parameters have been estimated for this stock, which are: L∞= 107·3 cm (t.l.), W∞=32 kg, AT=0·227 year‐1, M=0·45 year‐1. A yield per recruit analysis shows that the stock is underexploited for values of M bigger than 0·30 year‐1.
The induced spawning of roach, Rutilus rutilus (L.), with the antioestrogens clomiphene and tamoxifen
Authors: Worthington A. D. , Macfarlane N. A. A. , Easton K. W.
Published: January 2006

The induced spawning of gravid roach was investigated using the antioestrogens clomiphene and tamoxifen. Three dose levels ofeach were used: 0·1, l or 10 mgkg‐1, given twice with a 4‐day interval to groups of eight fish with saline controls. Running males were randomly distributed. Tamoxifen, when injected at a rate of l mg kg‐1 was found to be most successful. This treatment induced ovulation in five of the six females, and profuse spawning on 3 consecutive days, 4 days after the first injection. Clomiphene induced ovulation and spawning in one of six females at 2 × 10 mg kg‐1, and two of eight females at 2 × l mg kg‐1, respectively 6 and 7 days after the first injection. The eggs produced showed normal devel‐opment. No control fish ovulated or spawned. Both drugs probably act by indirect mechanisms, blocking sex steroid feedback inhibition of gonadotropin (GtH) secretion at the pituitary, thereby inducing a plasma GtH surge. The results of this experiment suggest that tamoxifen may be an effective substitute for pituitary preparations in the induced spawning of fish.
Secretin‐stimulated insulin release in vivo in European eels, Anguilla anguilla L
Authors: Ince B. W.
Published: January 2006

Plasma insulin and glucose responses to a secretin‐like factor, extracted from pike intestines, have been investigated in vivo in European eels, Anguilla anguilla L. Intra‐arterial injection of pike secretin elicited a dose‐related, significant increase of plasma insulin after 30 min at 100 and 250 μgkg‐1 body weight, but was without effect at 40μgkg‐1. Plasma glucose levels, however, remained unchanged over this dose range. These results suggest that hormonal factors of gastrointestinal origin may modify pancreatic endocrine function in teleost fish.
Muscle fibre types in the myotome of stickleback, Gasterosteus aculeatus L.; a histochemical, immunohistochemical and ultrastructural study
Authors: Kronnie G. te , Tatarczuch L. , van Raamsdonk W. , Kilarski W.
Published: January 2006

In myotomes of the stickleback three main complexes of muscle fibres were present. They comprised dwarf, intermediate and white fibres, which differed in regard to histochemical, immunohistochemical and ultrastructural features. In addition, dwarf fibres were divided into two categories on the basis of myofibrillar ATPase activity and cross‐reactions with specific antisera. Among intermediate muscle fibres it was possible to observe some ‘aberrant fibres’, which were characterized by low reactivity with and P‐myosin serum.
The reproductive biology of poor‐cod, Trisoptems minutus L., whiting, Merlangius merlangus L., and Norway pout, Trisoptems esmarkii Nilsson, off the west coast of Scotland
Authors: Cooper A.
Published: January 2006

The reproductive biology of poor‐cod, Trisoptems minutus L., whiting, Merlangius merlangus L., and Norway pout, Trisoptems esmarkii Nilsson, was studied in western Scottish waters. Sex ratios, size and age at maturation and spawning seasons were determined and compared with other areas. The large juvenile stocks found in inshore areas at the western entrance of the Great Glen were derived from spawning grounds west of Mull, in poor‐Cod. In whiting and Norway pout the location of spawning grounds was inferred from the occurrence of planktonic larvae and postlarvae and the hydrography of the area.
Effects of food supply on the reproduction of the convict cichlid, Cichlasoma nigrofasciatum
Authors: Townshend T. J. , Wootton R. J.
Published: January 2006

Cichlasoma nigrofasciatum, the convict cichlid, is a biparental, substrate‐spawning, Central American cichlid. Male‐female pairs were kept for 4 months on one of three food rations: high–1 g food daily; medium–1 g three times per week; low–1 g per week. The number of spawnings was directly related to the food ration. The fecundity of the females on the low and medium rations declined. At all rations the inter‐spawning interval and egg size increased during the experiment. Egg size was positively related to ration and the length of the inter‐spawning interval, but the latter was inversely related to ration. Females on the high ration grew in weight while those on the low ration lost weight. Histological examination of the ovaries at the end of the experiment suggested that low rations reduced the proportion of oocytes that become vitellogenic. At the end of the experiment, the total, gonad and liver weight of females at a given length were significantly related to ration. No similar, significant effect was found for the males, although growth in length of the males was related to ration. Ration had no detectable effect on the histological appearance of the testes.
The growth of largemouth bass, Micropterus salmoides (Lacepede), under constant and fluctuating temperatures
Authors: Diana J. S.
Published: January 2006

Growth of largemouth bass, Micropterus salmoides, was tested under constant (15° C, 29° C) and cyclic (18 h at 15°C, 6 h at 29° C) temperature conditions. Six groups of 10 fish each were tested; one group under each constant condition, and four groups in the thermocycles. The four latter groups differed in the timing of their feeding; one group each was fed at the start and middle of the warm and cool periods, respectively. All groups were fed to near‐satiation. The fish fed at the start of the warm cycle and start cool group grew most rapidly, followed by the constant warm, mid warm, mid cool, and constant cool groups. These data were evaluated in relation to vertical migrations of fish to test the physiological enhancements that may be important to vertical migrations. Apparently thermocycles allow more rapid consumption of food than constant cool conditions and lower metabolic rates than constant warm conditions, which allows some fish to grow more rapidly under thermocycles than under constant conditions at either extreme of the cycle. However, the timing of feeding in relation to temperature in the thermocycle is important in the degree of growth enhancement.
The metazoan parasites of freshwater fishes in the Corrib catchment area, Ireland
Authors: Conneely J. J. , McCarthy T. K.
Published: January 2006

A survey of the parasites of 243 fish belonging to 13 species, from the Corrib catchment area, western Ireland, was undertaken. At least 32 species of metazoan parasites were shown to be present. Diplostomum gasterostei, Tylodelphys clavata, Eubothrium salvelini, Cucullanus truttae, Raphidascaris acus, Ergasilus gibbus and Salmincola gordoni appear to be first records for Ireland and Phyllodistomum conostomum has not previously been reported from the British Isles. New host records involving Lamptera planeri, Salvelinus alpinus, Abramis brama, Noemacheilus barbatulus, Anguilla anguilla and Pungitius pungitius for the British Isles are given.
Protein histochemistry of the granule cells in the small intestine of the rainbow trout, Salmo gairdneri Richardson
Authors: Woodward B. , Bergeron T.
Published: January 2006

The histochemical nature of the protein within the large granules of the intestinal granule cells was examined in rainbow trout, Salmo gairdneri, from the time of earliest appearance of the cells in the lamina propria until a layer of granule cells was established in 12‐month‐old juveniles. At all times the granule cell granules contained large quantities of protein. This material appeared to be predominantly cationic in nature as judged from results obtained with alkaline fast green FCF together with deamination controls. In addition, there was no major acidic protein within the intestinal granule cell granules.
Growth dynamics of white myotomal muscle fibres in the bluntnose minnow, Pimephales notatus Rafinesque, and comparison with rainbow trout, Salmo gairdneri Richardson
Authors: Weatherley A. H. , Gill H. S.
Published: January 2006

The dynamics of increase of the predominant white muscle fibres of the myotomal bulk in bluntnose minnow, Pimephales notatus, ranging from 2.0 to 9.1 cm f.l. have been analysed by examination of modal progression of fibre diameter frequency classes in fish fed to satiation and growing at different rates at 15, 25 or 30°C. Recruitment of new fibres appeared to contribute little to increase in muscle bulk above 4 cm f.l., and nothing beyond 6 cm. The dominant means of increase was increase in fibre diameter. The limiting fibre diameter seemed to be 120 μ. These dynamics, which result in an approximately 1: 1 ratio between mean fibre diameter and f.l., are in contrast to those of the myotomal white muscle of rainbow trout, Salmo gairdneri, in which, regardless of differences in somatic growth produced by temperature, ration size or growth hormone administration, mean fibre diameter does not exceed that in bluntnose minnow until trout exceed 30 cm f.l. In trout there is, moreover, input of new fibres up to approximately 50 cm f.l., when subsequent growth, as in the minnow, is by means of fibre diameter increase. The bluntnose minnow is a small, slow growing species; the rainbow trout is a large, fast growing species. The discussion links these facts with the observed differences in fibre growth dynamics in relation to a hypothesis of interspecific differences in fish growth capability.
The distribution of Poecilancistrium caryophyllum (Trypanorhyncha) plerocercoids in spot, Leiostomus xanthurus Lacèpéde, and spotted seatrout, Cynoscion nebulosus (Cuvier)
Authors: Collins M. R. , Marshall M. J. , Lanciani C. A.
Published: January 2006

Spotted seatrout, Cynoscion nebulosus (Cuvier), and spot, Leiostomus xanthurus Lacèpéde, from two sites along Florida's west coast were collected, weighed, sexed and measured. A systematic search for plerocercoids of the cestode Poecilancistrium caryophyllum yielded infection prevalences of 81.9% for C. nebulosus and 25.0% for L. xanthurus. The maximum infection intensity was 10 (mean = 2.65) plerocercoids per fish in C. nebulosus and six (mean = 1.69) per fish in L. xanthurus. Significant correlations were found between infection prevalence and length in C. nebulosus, and a significant correlation was observed between intensity and length in both species. Condition coefficient (K) and intensity were negatively correlated in C. nebulosus but not in L. xanthurus. An iterative computer technique based on the truncated negative binomial distribution indicated no parasite‐induced mortality occurred in either species. Sand drum, Umbrina coroides Cuvier, is reported as a new host record for P. caryophyllum.
The tissue localization of Aeromonas salmonicida in rainbow trout, Salmo gairdneri Richardson, following three methods of administration
Authors: Tatner M. F. , Johnson C. M. , Horne M. T.
Published: January 2006

The localization of a live, and a formalized vaccine preparation of Aeromonas salmonicida within the tissues of rainbow trout, Salmo gairdneri, was followed over a 5 day period. When presented by intraperitoneal injection, both the live bacteria and the vaccine localized in the spleen, liver, kidney and gut. When presented orally, the bacteria and the vaccine were confined almost exclusively to the gut region. Direct immersion resulted in low detectable levels within the tissues, with the spleen and kidney localizing the Aeromonas after its initial attachment to the outer surfaces of the fish.
Age and growth of the sand shark, Rhinobatos annulatus, in Algoa Bay, South Africa
Authors: Rossouw G. J.
Published: January 2006

Annual rings on the vertebral centra were used to determine age in the sand shark, Rhinobatos annulatus. A 6% silver nitrate solution was applied to the concave surfaces of the vertebrae to clarify the rings. The monthly percentage frequency of opaque and hyaline peripheral rings were used to determine the annual nature of the rings. Both sexes can reach a maximum age of 7 years. Conventional growth curves could not be fitted and empirical curves were used to illustrate growth. Total body length at age was calculated from these curves and compared with observed data.
Cost of prey capture, growth rate and ration size in pike, Esox lucius L., as functions of prey weight
Authors: Hart P. J. B. , Connellan B.
Published: January 2006

Prey intake, amount of time feeding, pursuit and manipulation times and growth rate were studied in the pike, Esox lucius, in relation to prey weight. Predator and prey were observed in tanks at 15°C and with a 14:10 h LD photoperiod. A total of 444 captures were recorded from five 1 g prey weight groups varying from 0 to 4.9 g. Ten pike were used weighing between 50 and 149 g.

As prey weight increased, the number and weight of prey consumed decreased as did the time spent feeding, which became concentrated into the first trial of the day. Pursuit time did not vary with prey weight, but manipulation time and the weight of prey gained per unit pursuit plus manipulation time increased with prey weight.

The growth rate of pike was a positive function of ration size and a negative function of the amount of time spent capturing each gramme of prey (capture cost). Growth rate was also correlated with the mean length and weight of prey eaten.

The most profitable prey, as estimated from optimal foraging theory, need only be available once every 84 min for pike to maximize their net energy gain. The data show that feeding behaviour can have a direct influence on the reproductive success of pike through its effect on growth rate.
Some morphological effects of zinc upon the yolk‐sac larvae of Clupea harengus L.
Authors: Somasundaram B. , King P. E. , Shackley S. E.
Published: January 2006

Some effects of low concentrations of zinc on the eggs and yolk‐sac larvae of Clupea harengus L. are examined. Deformations of the jaw, head, optic capsules, otic capsules and vertebral column are described. With some of these deformations, induced by lower zinc concentrations, the larvae survive and continue development but others, in the higher zinc concentrations, die.
The effects of external ultrasonic tagging on the swimming performance of rainbow trout, Salmo gairdneri Richardson
Authors: Lewis A. E. , Muntz W. R. A.
Published: January 2006

The effects of externally mounted ultrasonic tags on the tail beat frequency (TBF) and opercular beat rate (OBR) of rainbow trout was measured at different swimming speeds. The increase in relative drag caused by the tags was also measured. Two tag types were used: one where both the circuitry and the battery were in a single package mounted on one side of the fish, the other where they were in two packages mounted symmetrically on either side of the fish. Both tag types raised both TBF and OBR. Of the two, the symmetrical tag effects behaviour less, especially at low swimming speeds, even though it causes a greater increase in relative drag.
Fish yield estimates for the Sepik River, Papua New Guinea, a large floodplain system east of ‘Wallace's Line’
Authors: Coates David
Published: January 2006

The fisheries of floodplain river systems in Africa, South America and Asia are similar and their yields can be estimated from various morphological, edaphic and other parameters. There is a close similarity in the ichthyofauna of these regions enabling comparisons between systems to be made. The native fauna of New Guinea (Australasia) is devoid of the primary freshwater fishes that compose the majority of the catch from other regions. Various estimates suggest that the present yield of the Sepik River fishery is about 3000–5000 t year−1 This is approximately 10% of the yield of 30 000–45 000 t year−1 predicted by comparison with African rivers. Much of the present catch is introduced tilapia. Considering the native fish species alone, the present yield is only about 5–7% of that predicted. Fishing effort in the Sepik may be low by comparison with African rivers but the faunal difference is probably the main factor involved. This low yield still represents one of the largest and most important fisheries in the country. Such yeild estimates, even if only rough approximations, are vital for planning and management decisions.
Cadmium dynamics in fish: pulse studies with 109Cd in female zebrafish, Brachydanio rerio
Authors: Karlsson‐Norrgren L. , Runn P.
Published: January 2006

The dynamics of a subtoxic pulse of non‐dietary 109Cd was followed for up to 304 days after the exposure period in female zebrafish. The retention of dietary 109Cd was also estimated.

The distribution of 109Cd was studied by autoradiography, whole‐body analysis and tissue sampling. After exposure to non‐dietary 109Cd for 10 days there was a rapid loss of 109Cd from the gills. The 109Cd content of the alimentary canal exceeded that which could have been expected from normal drinking. Based on the distribution pattern of non‐dietary 109Cd in tissues, two groups of tissues were distinguished:

the gills, alimentary canal and heart which showed maximum 109Cd values directly after exposure, followed by a pronounced decrease up to day 21;

the liver, kidney, ovary and muscle, in which there was a delay in maximum 109Cd activity to days 21–42, with subsequent loss.

Small amounts of 109Cd were noted in fry and fertilized eggs originating from zebrafish exposed to non‐dietary 109Cd. After exposure to dietary 109Cd, less than 5% was retained in the zebrafish body, mainly in the alimentary canal.