bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations on the age, growth, reproduction and food of the chub Squalius cephalus (L.) in the River Stour, Dorset
Authors: Mann R. H. K.
Published: January 2006

Opercular bones from 399 chub from the River Stour, Dorset were used for age and backcalculated growth measurements. Scales were only used to aid the interpretation of difficult operculars. Annuli were laid down through the period mid‐April to mid‐June. Growth in length was minimal between October and March. Growth rates were similar to those published for chub in other European waters, but the Stour chub were longer‐lived and attained a greater ultimate size. Female chub grew faster than the males. Spawning occurred from late May into June and elaboration of the gonads took place between September and May. Immature chub had an annual cycle of condition; the 0 group having a maximum in August and older immature fish reaching their maximum in June. Both categories had a minimum condition in early spring. The cycle of gonad development affected the condition of mature fish. The numbers of eggs in chub of lengths 359–467 mm ranged from 27 000–65 000. Some females attained sexual maturity at age V or VI, but most by age VII. The majority of males matured at age V, though some at ages III or IV. Growth rates and year‐class strengths varied from year to year but independently of one another. Thirty‐one per cent of chub aged II and over belonged to the 1959 year class. Young chub ate insect larvae and small crustacea, but the occurrence of fish and macrophytes was greater in the diet of older fish.
The histopathology of salmon tagging
Authors: Morgan R. I. G. , Roberts R. J.
Published: January 2006

Hatchery reared Atlantic salmon (Salmo salar L.) parr were tagged with the standard I.C.E.S./I.C.N.A.F. salmon tag at water temperatures of 15°C and 6°C. They were then subjected to swimming trials in a tunnel respirometer. Following this treatment the 15°C fish developed necrotic infarcts around the tag insertions. Provided they did not become infected these lesions healed, but if the fish were retested 9 days later, the wound enlarged, became extremely inflamed, and the fish died soon after. This effect was not seen in 6°C fish.
Experiments on the resistance of fish to rapid increase in hydrostatic pressure
Authors: Lampert Winfried
Published: January 2006

In a few hydro‐electric pumping stations in the southern Black Forest it has been found that fish occurring in the high lying reservoirs could only arrive there from the river below after an upward transport through the pumping system. As there is a height difference of 400 m to overcome the fish must withstand a sudden pressure change of 40 atm. To test whether this is actually possible various species of fish were subjected suddenly to a pressure of 50 atm which was then reduced to 1 atm over a period of 10 min.

No mortality occurred. Although the pressure shock symptoms exhibited by the different species of fish were variable, all appeared to be perfectly normal 2 h after the experiment.
Distribution, reproduction and growth of the catfish, Chrysichthys walkeri (Gunther) in the Lekki Lagoon, Nigeria
Authors: Ikusemiju Kola
Published: January 2006

An investigation was made on the biology of the catfish, Chrysichthys walkeri (Gunther) occurring in the Lekki Lagoon. The catfish was evenly distributed over the six sampled stations of the lagoon with the sites of the shallow water stations probably serving both as breeding and nursery grounds.

Fecundity estimates for this species ranged from 896 to 4168 eggs. The average number of eggs per female was 2084. Laboratory incubated eggs hatched after 3 days with the yolk sac being completely absorbed on the seventh day. The fry averaged 8.6 mm on their first day of life.

The catfish attained a maximum total length of 25.7 cm within a period of 2 years. There were no significant differences in the growth pattern of this species during the dry and rainy seasons.
The basis of food selection in flounders, Platichthys flesus (L.), in the Severn Estuary
Authors: Moore J. W. , Moore I. A.
Published: January 2006

The factors influencing the selection of food by flounders, Platichthys flesus (L.), have been investigated by analysing collections made in the Severn Estuary for 1 year and the results of experiments. Flounders measuring between 6–0 and 35 cm fed heavily on the polychaete Nereis diversicolor in February and on the amphipod Gammarus salinus between February and April. Thereafter these species were replaced by the mysid Neomysis integer with the decapod Crangon vulgaris. Flounders shorter than 6.0 cm, fed mainly on Neomysis integer regardless of month. Numerous factors were involved in the choice of the food including (1) the maximum and minimum length of prey, (2) its spatial distribution in the water column, (3) its degree of concealment, (4) its motility and ability to escape predation, (5) conditioning of the flounders for certain foods, (6) the fish's swimming speed and (7) the turbidity and temperature of the water.

Although the average length of ingested prey remained unchanged as the fish grew in size, an increase in the maximum and minimum lengths was observed. The percentage of stomachs that contained no identifiable remains in flounders greater than 6–0 cm averaged 80–95 % during part of the winter and 60% in the summer and between January and March. These changes partly reflected the influence of low water temperature on the metabolic rate and availability of prey. The dry weight of the stomach contents in flounders longer than 6–0 cm was lowest in winter but high values were recorded in the spring. This latter feature was probably because the rate of feeding was greater than that of digestion. During the summer, under more normal feeding conditions, the weight of the stomach contents remained relatively low compared to other fish populations. Flounders shorter than 6–0 cm always contained more food in their stomachs on a unit weight basis than larger individuals, reflecting metabolic rate and hunting efficiency.
Identification of the juvenile mullet of the east coast of South Africa
Authors: van der Elst R. P. , Wallace J. H.
Published: January 2006

Juvenile mullet are identified at the stage at which they first enter estuaries (10–50 mm in most species) through the use of dentition characteristics and lateral line scale counts. Techniques which simplify the determination of these features are described and a key to the 15 South African species is provided.
Availability, morphometrics, feeding and breeding activity in a multi‐species, demersal fish stock of the Western Indian Ocean
Authors: Darracott Ann
Published: January 2006

A multi‐species demersal fish stock was studied from April 1969 to July 1970. The common species are described in this paper and consist of Carcharhinus sealei, Rhynchobatus djeddensis, Dasyatis kuhlii, Rachycentron canadum, Psettodes erumei and Arius sp. With the exception of Rachycentron canadum, these fish were available throughout the year and some coincidence of increased availability was noted in August/September. Psettodes erumei, the commonest fish caught, was most available in August/September, February/ March and June. The size and weight distribution of each of these fish is described. Morphometric results indicate that two fish, Dasyatis kuhlii and Psettodes erumei, exhibit sexual dimorphism, the females being larger and heavier than the males. Carcharhinus sealei, Rhynchobatus djeddensis and Rachycentron canadum have a nearly isometric growth exponent whereas Dasyatis kuhlii, Psettodes erumei and Arius sp. have an allometric growth exponent. All fish were carnivores, Rhynchobatus djeddensis, Rachycentron canadum and Arius sp. being primarily crustacean feeders, Dasyatis kuhlii feeding on polychaetes and crustaceans and Carcharhinus sealei and Psettodes erumei feeding mainly on fish. The increased number of all three bony fish noted in August/September (immediately prior to the short rains in October/November) is discussed in relation to feeding activity and the initiation of spawning activity. It is suggested that spawning in Psettodes erumei and Arius sp. is initiated in September, continuing possibly to February and then during the long rains (March/May) and the South East Monsoon the fish recover. It is also suggested that pregnant elasmobranchs may come inshore in greater numbers during the rains to give birth.
Copper as an initiating factor of vibriosis (Vibrio anguillarum) in eel (Anguilla anguilla)
Authors: Rødsæther Marianne C. , Olafsen Jan , Raa Jan , Myhre Kjell , Steen Johan B.
Published: January 2006

Eels (Anguilla anguilla) which were exposed to copper‐contaminated fresh water (30–60 ρg Cu/I) died with signs of vibriosis (Vibrio anguillarum). Eels kept in non‐contaminated fresh water (<6ρgCu/I) remained healthy. V. anguillarum was shown to be present in the eels with symptoms of vibriosis. We suggest V. anguillarum is a common inhabitant of eels and copper can change a commensal association between fish and bacterium to one of pathogenicity.
The architecture of the gill surface of the catfish, Heteropneutes fossilis (Bloch): SEM study.
Authors: Rajbanshi V. K.
Published: January 2006

A scanning electron microscopical examination of the gills of H. fossilis is described. The surface architecture of gill filaments and secondary gill lamellae showed the presence of various features such as indentations, micropits and crevices. The possible functions of these morphological adaptations are discussed in relation to physiology of the gill.
A review of damsel fishes (Pisces: Pomacentridae) of the genus Chromis from the central and eastern Atlantic and the Mediterranean
Authors: Wood Elizabeth M.
Published: January 2006

The specific status of the damsel fish Chromis chromis (L) is discussed and it is suggested that Chromis chromis is retained for Mediterranean specimens and that Chromis lirnbatus is re‐introduced for the East Atlantic form. Behavioural and morphological differences which distinguish these two species are given. A key to these and other East Atlantic Chromis is provided, the species are described and their geographical range discussed.
A bibliography of parasites and diseases of marine and freshwater fishes of India
Authors: Natarajan P. , James P. S. B. R.
Published: January 2006

A total of 531 references on the parasites and diseases of marine and freshwater fishes of India which appeared in 90 scientific journals have been documented.
Uptake and loss of dissolved zinc by the stickleback Gasterosteus aculeatus L.
Authors: Matthiessen Peter , Brafield A. E.
Published: January 2006

Uptake and loss by sticklebacks of both stable zinc and 65Zn in hard and soft water have been studied for periods of upto400 h. In calcium‐free water, the 65Zn uptake curve is approximately asymptotic over a period of 24 h, while in hard water internal 65Zn levels are dropping at 24 h. Over 5 h, however, fish in hard tapwater absorb about 3.5 times more 65Zn than those in calcium‐free water. There is a positive linear relationship between log 65Zn uptake and log wet weight of fish. Whole‐body concentration factors (c.f.) at 16 h reach a maximum of 12.2 (mean=2.9), highest concentrations of 65Zn being found in the gills (mean c.f.=5.l) and lowest concentrations in the gonads (mean c.f.=0.8). Over longer periods (400 h), internal stable zinc levels offish exposed to 1 and 4 p.p.m. Zn2+ remain little higher (max 28 %) than controls. 65Zn efflux into zinc‐free water falls to zero after 5 h, more zinc (78 %) being lost after uptake in tapwater than in calcium‐free water (56 %).
A review of the bacterial flora of teleosts and elasmobranchs, including methods for its analysis
Authors: Horsley R. W.
Published: January 2006

Techniques for the quantitative and qualitative analysis of the commensal bacterial flora of fish are reviewed. The literature concerning the commensal bacterial flora of fish indicates that teleost skin often features 102–07 organisms per cm2 of skin, representing the following taxa, in descending numerical order, Achromobacter, Pseudomonas, Flavo‐bacterium and Cytophaga species also coryneform organisms. Actively feeding teleosts appear to have an alimentary canal bacterial flora similar to that of the skin and gills, often there are from 103–108 organisms per 1.0 g, wet weight, of tissue. According to the limited data available for elasmobranchs Gram–positive bacteria are the predominant component of the bacterial flora on the skin of sharks, though the bacterial flora of North Sea skate (Raja spp.) is reported as being similar to that of teleosts. The commensal flora of fish, particularly of teleosts, is related to their environment and is influenced by environmental changes that affect the quality of the water. Regular monitoring of the water of commercial fish ponds and aquaria for bacterial quality, temperature, dissolved oxygen concentration and pH, combined with a base–line knowledge of the water's quality, may provide an advanced indication of the presence of bacteria potentially able to produce diseased conditions, and factors that will enhance their growth.
A trypanosome from the plaice, Pleuronectes platessa L.
Authors: Cottrell B. J.
Published: January 2006

The results of a 12 month study of Trypanosoma platessae Lebailly (1904), a haemoflagellate parasitising the plaice, Pleuronectes platessa L., are presented. The morphological features of the trypanosome are described, with experimental investigations of the host specificity of T, platessae. The flagellate occurred at low parasitaemias in wild plaice with a seasonal variation in the numbers of infected hosts, the percentage of parasitised fish reaching a maximum of 20 % in March and declining in the summer months.

Attempts to establish T. platessae in the laboratory, by means of passage of infected blood, gave inconsistent results. Elevated levels of β‐globulins were detected in the sera of T. platessae infected plaice, and it is suggested that this may be associated with antibody secretion to the parasite.
Age, growth and feeding in the ballan wrasse Labrus bergylta Ascanius 1767
Authors: Dipper F. A. , Bridges C. R. , Menz A.
Published: January 2006

A study of the age, growth and feeding of the protogynous wrasse Labrus bergylta (Teleostei: Labridae) was made on 25 male and 316 female specimens taken from the southern coasts of the Isle of Man from October 1972 to October 1974. Age determination and back‐calculations for length were made from the opercular bones. The oldest male and female specimens were 29 and 25 years old respectively. The growth curves showed only a slight increase in growth rate after sexual inversion, and a pattern of slow irregular increase, with no pronounced levelling off in old fish. The time of sexual inversion varied widely: intersexual specimens of 5 and 14 years were found. The youngest functional male was 6 years old. The weight/length relationships of males and females were very similar and the following equation, derived from all individuals, was used to calculate weights for age utilizing the back‐calculated lengths:

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The mouth, pharyngeal teeth and gut length to fish length ratio (0.622) suggested an omnivorous diet. Analysis of gut contents confirmed this, with decapod Crustacea, isopods and molluscs the dominant food items. There were seasonal changes in feeding intensity and composition of the diet, related to temperature changes, onshore‐offshore migration patterns, availability of food items, and changes in habitat associated with maturation.
Effects of hypercapnia on the buffer capacity and haematological values in Salmo salar (L.)
Authors: Börjeson Hans
Published: January 2006

The effects of high environmental carbon dioxide tension (PCO2) on buffering status, pH, haematocrit, red blood cell (RBC) count, mean corpuscle volume (MCV), and chloride (Cl–) distribution in the blood of young salmon were investigated after 30 min and 24 h. An increase in blood buffering capacity was observed after 24 h. As compared to the preacclimation situation, haematocrit, RBC, MCV and Cl– content of the erythrocytes increased after 30 min but decreased if hypercapnia was sustained for 24 h. However the plasma bicarbonate (HCO3) content increased over the whole experimental period. Plasma Cl– content was decreased after 24 h, but the ratio of Cl– between erythrocytes and plasma increased at the onset of hypercapnia, then remained unchanged during the rest of the investigation period.
A technique for determining the distribution of pelagic fish larvae
Authors: Coles T. F. , Swinney G. N. , Jones J. W.
Published: January 2006

A technique is described for studying small scale distributional patterns of fish larvae in the pelagic region. A plankton net is mounted beneath the bows of a small boat, the contents of the net are emptied continually by a suction pump. This system has advantages over previous techniques as it allows a large number of small discrete samples to be taken over a wide area in a short space of time. Preliminary results showed the population of perch larvae in Llyn Tegid is extremely clumped and the overall abundance of the larvae decreases as samples are taken progressively further away from the south‐west end of the lake.
Seasonal changes in the day and night activity of adult perch, Perca fluviatilis L.
Authors: Craig John F.
Published: January 2006

Perca fluviatilis L. were caught by gill nets every 3 h over a 24 h period monthly from February 1975 until January 1976. The numbers caught increased with rise in temperature (correlation coefficient r= 0.86 P < 0.001). During the winter months perch migrated into deeper water although some fish were still caught in shallow water (1–6 m). Perch were active at very low light intensities. However changes in visual surface irradiance (400–700 nm) and water clarity caused inverse changes in activity. Only June did not conform to this pattern and it was presumed that spawning behaviour was of primary importance. It is suggested that increase in eutrophication with its effect on water clarity enables fish to become more active during the day in the summer months. They are thus able to utilise food sources to a maximum at an optimum period for feeding and growth.
Electron microscopy of wound healing in the skin of Gasterosteus aculeatus
Authors: Phromsuthirak Pramarn
Published: January 2006

The process of healing of a small surgical incision in the skin of Gasterosteus aculeatus has been studied by electron microscopy. The wounds were made in the mid‐ventral line where no muscle intervenes between the skin and the peritoneum. The epidermis moved in through the incision and spread outwards beneath the dermis; the migrating epithelial cells were shown to be phagocytic. The wound was closed when cells at the surface of the epidermis met across the gap, forming a plug of epidermal tissue which was then invaded by dermal tissue from either side. Formation of new basement membrane apparently depended on the interaction of epidermal and dermal components. Leucocyte types were identified by electron microscopy; acid phosphatase tests were positive in macrophages and in neutrophil granulocytes, negative in lymphocytes and in eosinophil granulocytes. These four types of leucocyte are present in normal skin; after wounding, more migrated into the epidermis from the blood. The number of neutrophils in the epidermis reached a peak 24 h after wounding and declined during the second day. The number of macrophages rose to a peak by the third day and returned to normal by day 8. The numbers of eosinophil granulocytes and of lymphocytes showed little change. Neutrophil granulocytes were shown to be phagocytic, although not to the same extent as the macrophages.
Serum protein changes in brown trout (Salmo trutta L.) after single injections of soluble and cellular antigens
Authors: Ingram George A. , Alexander John B.
Published: January 2006

Brown trout sera were examined by cellulose acetate (CAE) and polyacrylamide electrophoresis (PAE) and the protein concentrations measured by the Lowry method, before and after stimulation with haemocyanin, horse serum, Salmonella typhi‘H’ and human group ‘O’ erythrocytes. Uninjected fish contained 5.l1±0.71 g protein/100 ml. Protein concentration was unaffected by haemocyanin and horse serum but was significantly lowered by S. typhi and human group ‘O’ erythrocytes. Male and female fish gave similar responses. Uninjected and injected fish showed 8 components on CAE and 16 on PAE. Significant differences were found between injected and uninjected control fish and between antigen stimulated and uninjected controls.
Heart rate as a measure of metabolic rate in teleost fishes; Salmo gairdneri, Salmo trutta and Gadus morhua
Authors: Priede I. G. , Tytler P.
Published: January 2006

Measurements of oxygen consumption and heart rate showed that the range of variation in metabolic rate for any given heart rate in fish is too wide for any significant correlation to be used as a measure of metabolism as in some other vertebrates. By defining the maximum oxygen pulse a precise relationship can be established between maximum metabolic rate and heart rate. From field measurements of heart rate by telemetry useful information can be gained on metabolic rates.
A surgical operating apparatus for fish and its use in the pinealectomy of salmonids
Authors: Goetz F. W. , Hoffman R. A. , Pancoej W. L.
Published: January 2006

A surgical operating apparatus for fish that is effective for cranial surgery is described. The fishes are secured with clamp‐arms which extend against the pectoral and pelvic girdles. The head is held by a plexiglass mouthpiece, designed specifically for the fish species under investigation. The mouthpiece is also responsible for gill irrigation. The use of the apparatus for the surgical pinealectomy of salmonids is described.
Acute toxicity of inorganic chloramines to early life stages of brook trout (Salvelinus fontinalis)
Authors: Larson G. L. , Hutchins F. E. , Schlesinger D. A.
Published: January 2006

The acute toxicity of inorganic chloramines to brook trout alevin, fry, and juvenile life stages was determined in 96‐h tests. Toxicity was not constant between the life stages. Alevins were more tolerant than the fry group tested. Alevins showed a decreased tolerance with an increase of body weight. Two groups of juveniles were similar in tolerance to the heaviest alevin group. A relationship between life stage‐body weight of brook trout and 96‐h median tolerance limits is presented.
Some effects of exposing rainbow trout (Salmo gairdneri Richardson) to phenol solutions
Authors: Swift D. J.
Published: January 2006

Phenol (C6H5OH) at non‐lethal concentrations in hard water had no effect on the urine flow rate or haematocrit of rainbow trout for exposure times of 24 h. Phenol was detected in the urine in a non‐conjugated form and unchanged phenol was also extracted from muscle, blood and brain. Uptake of phenol into tissue was found to be rapid with an equilibrium concentration being reached in 3 h. Loss of phenol after exposure was as rapid. The equilibrium concentration for muscle was similar to the phenol concentration to which the fish were exposed. Blood and brain contained smaller amounts. Close to or above the lethal threshold concentration (48‐h lc509 mg 1‐l; 15°C) the fish had higher than ambient concentrations in their tissues most notably in the brain. Above the lethal threshold there is evidence of a large uptake of phenol by erythrocytes.
Cytological evidence for temporal differences during the asynchronous ovarian maturation of bisexual and unisexual fishes of the genus Poecilia
Authors: Monaco Paul J. , Rasch Ellen M. , Balsano Joseph S.
Published: January 2006

Comparisons based upon morphological features and cytochemical staining properties of chromatin, nucleoli, and the ooplasm were used in the present analysis of ovarian maturation in wild‐caught Poecilia mexicana and its related gynogenetic diploid and triploid' species'. Using an empirically derived ovarian maturation index, seasonal and collection site differences were found between the unisexual and bisexual forms. These fish seem equally suited to their environments. However, our data indicate that differences in microhabitat can have a profound influence on oocyte development. Although females of Poecilia spp. have asynchronous cycles of ovarian maturation, we could not detect any peculiar cytological events associated with the gynogenetic mode of reproduction. Sperm were found in ovaries of both unisexual and bisexual forms indicating that the unisexuals can compete effectively with females of P. mexicana for matings with males of this species. The methods employed in this study provide a sensitive measure of reproductive potentials in sympatric species.
'Siamese‐twins’ in Sarotherodon mossambicus
Authors: Hulata G. , Rothbard S.
Published: January 2006

Tilapia mossambica (Sarotherodon mossambicus (Trewavas, 1973)) a female mouthbreeding cichlid, Fryer & Iles (1972), has recently been introduced to the Fish and Aquaculture Research Station, Dor, from South Africa. They were found to spawn freely in aquaria. Females carrying eggs in their mouth are routinely transferred to small containers, and when the fry are released they are separated from their mothers.

In one batch of 209 fry we found two fry connected at their ventral part to the same yolk sack. These' Siamese‐twins' survived for 8 days in an aerated glass jar. During this period the yolk sack was absorbed and they became connected at their abdomens. (Plate I). Similar cases were previously noted in sharks, trout, Salmonidae spp., guppy, Poecilia sp. and Haplochromis sp. (Reichenbach‐Klinke & Elkan (1972) and Reichenbach‐Klinke (1972)).
Possible pheromone mediated reproductive isolation in two species of cyprinid fishes of the genus, Brachydanio
Authors: Bloom Herbert D. , Perlmutter Alfred
Published: January 2006

A sex pheromone of the zebrafish, Bracliydanio rerio, previously shown to attract conspecifics is here shown to repel a closely related species, B. albolineatus. The repellent action is considered as a possible population isolating device in these geographically and taxonomically closely related cyprinid fishes.
Pathology and biochemical genetic variation in the milkfish, Chanos chanos
Authors: Smith A. C.
Published: January 2006

Milkfish, Chanos chnos, were sampled from two geographical areas in the Hawaiian Islands approximately 200 miles apart, from Pearl Harbor on Oahu, and Puako on Hawaii. Differences in the incidence of gastritis, a stomach inflammation, and electrophoretic patterns of nuclear lens proteins from fish of the two areas suggested they were separate populations. Genetically, the pattern frequencies indicated homogeneity in the Pearl Harbor fish and heterogeneity in the Puako fish. The former may be a small population in which homozygousity was produced through genetic drift. The genetic heterogeneity of the Puako fish may indicate a single large population or a mixture of populations. These observations support the hypothesis, previously deduced from field studies, that milkfish have many nearshore spawning areas over a wide geographical range and, therefore, little opportunity for genetic interchange between the fish from widely separated areas. Pearl Harbor fish had the highest incidence of gastritis, which appeared to be due to a combination of polluted water and a possible genetic susceptibility to disease from inbreeding.
The status of brown and rainbow trout, Salmo trutta and S. gairdneri as hosts of the acanthocephalan, Pomphorhynchus laevis
Authors: Kennedy C. R. , Broughton P. F. , Hine P. M.
Published: January 2006

The status of brown and rainbow trout as hosts ofPomphorhynchus laevis was studied in the field and by means of laboratory investigations. Field data indicated that rainbow trout might belong to the group of preferred hosts of P. laevis, whereas brown trout belonged to the group in which the parasite achieved less than optimal growth and maturation. This was confirmed by laboratory infections. In rainbow trout P. laevis attained up to three times the growth rate in brown trout and maturation occurred whereas in brown trout establishment was lower, growth slower and no parasites matured. Changes in the behaviour of infected Gammarus pulex induced by the presence of P. laevis cystacanths were such as to render the shrimps more vulnerable to predation by trout and other surface and mid‐water feeding fish, and selective predation upon infeged G. pulex by fish was demonstrated. nvestigations into the stimuli necessary for eversion of cystacanths of P. laevis revealed that the most important factor was a non‐specific component of bile, and it was concluded that cystacanths were likely to evert in any species of fish. Recognition of the different status of brown and rainbow trout as hosts of P. laevis still fails to explain some peculiarities in the distribution of the parasite in the British Isles, where in Britain it occurs in trout in only one river but in Ireland in all rivers throughout the country. It is suggested that the Irish parasites may constitute a different strain of P. laevis, since they use a different species of intermediate host and are better able to survive in brown trout.
Cadmium and zinc content of fish from an industrially contaminated lake
Authors: Murphy B. R. , Atchison G. J. , McIntosh Alan W. , Kolar D. J.
Published: January 2006

Eleven species of fish from an industrially‐contaminated lake were analysed for whole body cadmium and zinc content by atomic absorption spectrophotometry. Cadmium and zinc content of fish were species related, and most species accumulated these trace metals to levels significantly higher than background. Maximum concentrations detected were 13.60 μg Cd g−1 (dry wt) in a bluegill and 820 μg Zn g−1 in a redear sunfish. Cadmium content was much more variable than zinc content. Distributions of concentrations of both cadmium and zinc in fish were lognormal, and concentrations of both metals tended to decrease in higher trophic levels. Zinc concentrations significantly decreased as total length increased in three species.
The host—parasite relationship of two copepod species and two fish species
Authors: Bortone S. A. , Bradley W. K. , Oglesby J. L.
Published: January 2006

A total of 2494 Menidia beryllina and 717 M. peninsulae (Atherinidae) were examined from the Pensacola Bay area for parasitic copepods. M. peninsulae was infested with Bomolochus concinnus (Bomolochidae) and Ergasilus marticatus (Ergasilidae) and had incidences (and intensities) of 12.3% (1.6) and 4.2% (1.3), respectively. Only seven M. peninsulae were infested with both species of parasites. M. beryllina was infested only with E. manicatus and showed different incidences (and intensities) in two areas: Mulatto Bayou, 13.2% (1.9); Catfish Basin, 53.0% (2.3). Fishes with parasites were significantly longer than fishes without parasites and the case of increasing number of parasites with increasing fish length was reinforced. B. concinnus is a warm water parasite on M. peninsulae while E. manicatus acts as a cold water parasite on M. peninsulae and a warm water parasite on M. beryllina. The parasites tended to be overdispersed on their hosts but at the same time showed evidence of negative intraspecific associations within a host. These data suggest intraspecific avoidance by the parasite but active acquisition by the host.
Storage of marine fish erythrocytes in liquid nitrogen
Authors: Chao L. P. , Birkbeck T. H.
Published: January 2006

The preservation of erythrocytes from cod (Gadus morhua), saithe (Pollachius virens) and mackerel (Scomber scombrus) at −196° C was studied using dimethyl sulphoxide (DMSO) as a cryoprotectant. Erythrocyte recoveries of greater than 90% were obtained from all species and cod erythrocytes were stored for eighteen months with insignificant lysis. Larger quantities of blood were stored by removal of plasma from citrated blood prior to the addition of DMSO solution, and by storage of pelleted frozen blood in aluminium canisters in liquid nitrogen. Maximum recoveries of washed intact erythrocytes required thawing of pellets in 125% DMSO solution and washing with buffer containing decreasing concentrations of DMSO. Washed erythrocytes kept at 4° for at least two days showed little haemolysis, were morphologically similar to fresh erythrocytes and equally susceptible to the δ‐haemolysin of Staphylococcus aureus.
The histological picture of the hypothalamus (the nucleus preopticus) and hypophysis in male Anguilla anguilla L. treated with hormones
Authors: Sokolowska M. , Epler P. , Bieniarz K.
Published: January 2006

Studies were conducted on the effect of human chorionic gonadotropin (HCG), testosterone and desoxycorticosterone acetate (DOCA) on the histological picture of the nucleus preopticus (NPO), hypophysis and gonads of male European eels. It was ascertained that none of the injections used changed the content of the Gomori‐positive material within the NPO cells. HCG and testosterone injections altered the histological picture of the hypophysis and injections of HCG influenced the gonads by accelerating their maturity. The injections of DOCA did not change the histological picture of the hypophysis and gonads in male eels.
Ketone bodies in fish skin mucus as an indicator of starvation: a preliminary report
Authors: Ramos Franklin , Smith Albert C.
Published: January 2006

The detection of starvation is a major problem in fish husbandry. Too often the discovery of starving animals is not made until pathogenic organisms are about to overcome the weakened animals. A simple test, using a commercial plastic strip with a reagent area that changes colour in the presence of starvation‐induced ketones, was applied to this problem in the mullet, Mugil cephalus. The strip identified ketones in the fish skin mucus, and demonstrated its value in detecting starvation in fishes.
Hybrids of chub and roach (Leuciscus cephalus and Rutilus rutilus) in English rivers
Authors: Wheeler Alwyne , Easton Keith
Published: January 2006

The occurrence of hybrids between chub, Leuciscus cephalus, and roach, Rutilus rutilus, from three rivers in England is reported. The hybrids are described and illustrated, and means of identification are indicated. Chub X roach hybrids, like those between other leuciscine cyprinid species, can be positively identified by the number and form of the pharyngeal teeth.
Seven years on – A continuing investigation of salmonid stocks in Lough Erne tributaries
Authors: Kennedy G. J. A. , Strange C. D.
Published: January 2006

An electrofishing survey of Lough Erne spawning streams indicates a continued decline in the populations of juvenile salmonids. This is particularly the case with salmon stocks, which are now seriously depleted or absent from the sampled areas. This finding complies with the recorded decline in the adult salmon escapement to the Erne system. Stocking operations of both salmon and trout appear to have been successful in boosting recruitment only on a localised basis.
An investigation into the growth of 0‐group roach, (Rutilus rutilus L.) with special reference to temperature
Authors: Broughton Nigel M. , Jones Neville V.
Published: January 2006

The growth of 0‐group roach in a chalk‐fed river is traced over six seasons and the growth compared to that in a nearby gravel pit. The growth rate, the daily weight increase and the condition of the fish are all highest during the summer, falling to a minimum over the winter period and rising again in the spring. Considerable yearly variation in the growth of roach in the river was observed and correlated with water temperatures above 14° C. It is suggested that water temperature, acting through the food supply, is the dominant factor governing growth. The hot summer of 1976 appears to have resulted in excellent growth of roach in both habitats.
The biology of a Scottish population of Fries' goby, Lesueurigobius friesii
Authors: Gibson R. N. , Ezzi I. A.
Published: January 2006

The biology of a Scottish population of the burrowing goby Lesueurigobius friesii was studied from February 1975 until October 1976. The fish lives at depths of 10–130 m on muddy grounds and attains a length of at least 94 mm and an age of 11 years, females generally living longer than males. Most growth takes place in the first three years of life after which it proceeds very slowly. Marked differences in year‐class strength were found. Both sexes mature in their third year and the breeding season lasts from late May until August. Each female can spawn at least twice during this period and the eggs are laid on the roof and sides of the U‐shaped burrows which the fish dig in the mud. Fecundity is length dependent and varies between approximately 3–11 000. The fish feeds predominantly on polychaetes, although small Crustacea and molluscs also feature commonly in its diet. No marked diurnal variation in the feeding pattern was noticed, although the amount of food in the stomachs was lowest in the early hours of the morning.
Relationship of season, thermal loading and red‐sore disease with various haematological parameters in Micropterus salmoides
Authors: Hazen Terry C. , Esch Gerald W. , Glassman Armand B. , Gibbons J. Whitfield
Published: January 2006

One hundred and fifty largemouth bass (Micropterus salmoides) were caught during the mid‐winter and mid‐summer months in Par Pond, an 1120 ha cooling reservoir located on Savannah River Plant near Aiken, SC. Equal numbers of fish were taken from ambient and thermally altered (> 10° C ambient) areas of the lake. The total length and weight of each bass was noted, along with the presence or absence of lesions associated with red‐sore disease (caused by the bacterium, Aeromonas hydrophila and the ciliate, Epistylis sp.). Blood was drawn, by heart puncture, from each bass and the following haematological parameters measured: haematocrit, haemoglobin, iron, total iron‐binding capacity, thyroxine, sodium and potassium. Only the total iron‐binding capacity was significantly higher in bass with red‐sore disease; none of the other blood parameters were significantly different in infected and uninfected bass. Bass from thermally altered locations had consistently higher haematocrits during both summer and winter. Bass from thermal and ambient locations were not different with respect to iron, iron‐binding capacity, sodium or potassium levels. However, bass taken during summer months had higher levels of circulating iron than individuals in winter months. Summer bass had higher thyroxine levels than bass in winter. These results are discussed in terms of their relationship to red‐sore disease, season and the impact of thermal effluent.
Effects of DL–thyroxine on swimming speed in pearl danio Brachydanio albolineatus (Blyth)
Authors: Katz Anne Harris , Katz Harvey M.
Published: January 2006

Pearl Danios (Brachydanio albolineatus–Blyth) were allowed four days for acclimation in river‐water filled aquaria maintained at a mean temperature of 27° C. A different concentration of DL‐thyroxine (T4) was added to each of two aquaria. A third aquarium served as a control and received no hormone. Photoperiod, feeding, aeration, and observer interference were controlled so as not to influence the results of the study. Mean swimming speeds for the fish in each aquarium were calculated. Data were subjected to analysis of variance and the Student‐Newman‐Keuls Test. Compared with the control, significant (P< 0.05) increases in swimming speed were found with concentrations of thyroxine in water of 1:4x 106 and 1:1 x 106. The difference in swimming speed between the two hormone‐treated groups was not significant. The fact that exogenous thyroxine will increase swimming speed may indicate that endogenous thyroid hormone plays a significant role in such fish behaviour as migration.
Periodicity in Atlantic salmon Salmo salar L. smolt migration
Authors: Thorpe J. E. , Morgan R. I. G.
Published: January 2006

Behavioural and physiological mechanisms postulated for the control of downstream migration of Atlantic salmon smolts are reviewed briefly, and some new evidence is presented for their refusal to undergo sustained swimming. Although these mechanisms imply passive displacement as the primary means of emigration, it is likely that active components must also exist as the rates of travel of smolts through loch systems are only slightly slower than those recorded for river systems. The timing of these movements within 24 h periods is reviewed and it is shown that the predominantly nocturnal emigration pattern is evident on occasions in alevin, fry and parr stages also. Thus at migration the diel periodicity probably represents a seasonal locomotor rhythm which, under changed behavioural and physiological circumstances, results in downstream displacement.
Some observations on salmon smolt migration in a chalkstream
Authors: Solomon D. J.
Published: January 2006

Observations on smolt migration in a chalkstream over a period of four years indicate a relationship between number of fish migrating during the day and maximum afternoon water temperature. Few fish move below an apparent threshold temperature. This threshold appears to be different each year, varying with the general water temperature of the period proceeding the main run. Tests made with dummy telemetry tags indicate that their use to observe natural migratory behaviour may be justified.
Diel rhythm in activity of walleye, Stizostedion vitreum vitreum
Authors: Kelso J. R. M.
Published: January 2006

Walleye, Stizostedion vitreum vitreum, generally moved along shore, mostly within 100 m, and were relatively inactive during the day. Activity, probably in relation to feeding, increased coincident with changing light intensity during the onset of darkness and daylight. Data were corroborative from ultrasonic tracking, gill net catches and echograms. Ultrasonic telemetry indicated that the majority of swimming speeds, 86%, were below 1 B.L. s−1 and maximum swimming speeds, up to 3.7 B.L. s−1, coincided with periods of maximum catches by gill net shortly after dusk. Walleye were consistently in the essentially homo‐thermous epilimnion and did not experience wide variations in ambient temperature. However, since light strongly influences activity, it is likely that light level rather than temperature limits the depth distribution of walleye.
Avoidance experiments with homing shoals of minnows, Phoxinus phoxinus in a laboratory stream channel
Authors: Stott B. , Buckley B. R.
Published: January 2006

In a laboratory stream channel consisting of two tributaries joining to form a ‘river’ it proved possible to establish three populations of minnows in separate home ranges. Minnows in the apparatus avoided water with low concentrations of dissolved oxygen but returned to the home range when aerated water was re‐established. Concentrations of 4, 8 and 10 mg 1−1 of phenol did not cause avoidance behaviors, in fact the highest concentration killed some fish, but activity levels were severely depressed and shoaling behaviors was also affected.
Heavy metals in relation to the biology of the mummichog, Fundulus heteroclitus
Authors: Chernoff B. , Dooley J. K.
Published: January 2006

Heavy metal levels of cadmium, copper, mercury, manganese, and zinc were examined in the mummichog, Fundulus heteroditus from industrialized and non‐industrialized environments. With one exception, the environment with the highest trace metal in its waters, had the fishes with the highest metal concentration. Except for mercury, the concentration factor varied inversely with the metal concentrations of the fish and water, suggesting a possible regulatory mechanism for metals in the tissues of mummichogs from environments with high metal concentrations. There was an inverse relationship between standard length and concentrations of zinc, manganese, copper and cadmium in whole male and female fishes. The viscera contained significantly greater concentrations of these metals than somatic muscle tissue. There were also significant differences between males and females with respect to whole‐body zinc and copper concentrations, but no sex differences for manganese and cadmium.
Observations on the spawning seasons of East African reef fishes
Authors: Nzioka R. M.
Published: January 2006

Between 1974–1977 the gonads of a number of commercial reef fishes were examined during a study of gear improvement and stock assessment along the East African Coastal waters. Different methods of fishing ranging from modern methods of trawling to local methods of traps were used. Twenty‐one families with a total of 73 species were examined. The spawning of these species occurred throughout the year with two peaks in January to March and September to November. The highest peak of breeding was in October, corresponding to the time of the South East Monsoons, and to the highest water temperature.
Copepod ectoparasites of Merlangius merlangus and Platichthys flesus
Authors: van den Broek W. L. F.
Published: January 2006

Seasonal changes in the levels of copepod ectoparasitic infections from Merlangius merlangus and Platichthys flesus were examined and related to the annual migrations of young fish into an estuary. Lernaeocera branchialis (L.) was the only parasite common to both fish species; its life‐cycle stages infected the branchial chambers of 96·7% flounders (P. flesus) and 40·4% whiting (M. merlangus). Infection in the two fish species exhibited similar seasonal fluctuations and a temporal relationship between the parasite's occurrence on its two hosts was apparent. Whiting were also parasitized by Clavella uncinata (Milller); 26·9 % fish were affected. The copepods' distribution was highly localized with the majority restricted to the long gill rakers of the first gill arch. Infection was related to size of whiting up to 12·5 cm; there was little increase beyond this length. In addition to L. branchialis, flounder was also host to Acanthochondria depressa (T. Scott) and Lepeophtheirus pectoralis (Müller). A. depressa showed a preference for the ocular side of the body with its developing stages attached mainly to the second gill arch and the adults located in the posterior pocket of the branchial chamber. L. pectoralis was associated with the paired fins. Factors which could result in such localized distributions are discussed.
A cinematographic investigation into the fish's bioelectric breathing signal
Authors: Gruber D. , Cairns J. , Dickson K. L. , Hendricks A. C.
Published: January 2006

The buccal‐ventilatory movements of bluegill sunfish, Lepomis macrochirus and fathead minnows Pimephales promelas and strip chart recordings of these movements were filmed simultaneously. The amplitudes of the ventilatory signals were greatest when a fish was perpendicular to the plane of either electrode, and the polarity of a signal corresponded to the fish's direction to one of the electrodes. The most common breathing waveforms for both species reflected a bimodal pattern. These patterns varied in frequency and shifted toward single modality in response to stress. Portions of the recorded waveforms consistently coincided with the period in which a fish was displaying either full opercular flare or closure. Similar occurrences corresponded with mouth positions. Several commonly occurring variations of the ventilatory signal waveforms are presented, including the response of bluegill sunfish to a strong concentration of chlorinated water.
Studies on the biology of reproduction in the cichlid Tilapia nilotica (L.): gonadal maturation and fecundity
Authors: Babiker M. M. , Ibrahim H.
Published: January 2006

Tilapia nilotica reaches maturity in the first year of life; females mature shortly before males (11·4 and 14·3 cm in length). The distinctive morphological features of the different stages of development of the gonads are characterized. The sex ratio varied in populations of different age (size)‐groups: a ratio of 2·81:1 and 0·47:1 (females:males) was obtained in populations of young and old fish. In medium‐sized populations the sexes were equally abundant. There is evidence that females breed more than once a season. Fecundity varied more with body length (r=0·860) and weight (r=0·806) than with age (r=0·604). These variations were of the order of 2·02; 0·83 and 0·83 exponentials of length, weight and age, respectively.