bluuebunny/crossref_metadata_2025 huggingface dataset:
The biology of the twaite shad, Alosa fallax fallax (Lacépède), in the Severn Estuary
Authors: Aprahamian M. W.
Published: January 2006

The estuarine biology of the twaite shad was studied in the Severn Estuary. Adults enter the estuary at the start of the freshwater phase of their spawning migration between April and June. Peak immigration generally occurs in May and is associated with temperatures in the range 10.6–12.3°C. The mean (±s.d.) instantaneous mortality rate for the mature population was 0.53±0.18. The effect of additional mortality on the spawning population was modelled assuming constant recruitment and no density‐dependent effects.

Juvenile twaite shad are present in the estuary from July until they emigrate seaward during the autumn. A portion of these fish re‐enter the estuary the following April–May and remain until late summer/early autumn before once more migrating seaward.

The 0 + age group feed mainly on harpacticoid and calanoid copepods and mysids, the relative preponderance of these in the diet being apparently related to tidal conditions. The possible implications of the proposed tidal power barrage in the Severn Estuary on the twaite shad population are discussed in relation to movement, diet and additional mortality of the mature population.
Migrations of elvers and juvenile European eels, Anguilla anguilla L., in the River Thames
Authors: Naismith I. A. , Knights B.
Published: January 2006

The up‐river migration of eels in the R. Thames has been studied at a number of locations since 1985. The run occurs between April and October, with the majority of eels moving over a distinct period averaging 47 days in May–June. The timing of the run varies and its commencement appears to be mainly dependent on water temperature. The number of unpigmented elvers migrating from the estuary to fresh water is variable and most appear to spend at least one year in the estuary. The average size and age of migrants increases with distance upstream. Migrants leaving the estuary were mainly 1–3 river‐year (<14 cm) pigmented juveniles, though individuals of up to 45 cm were encountered. At a site 15 km from the estuary the majority of migrants were between 4 and 8 river‐year eels (20–30 cm). Mark–recapture studies showed variable tendencies to display migratory behaviour among individuals, with some taking up to 2 years to reappear in a trap when released a few hundred metres below it. The implications of the results with respect to the commercial fishery in the estuary, populations in the catchment, and the contribution of Thames eels to international stocks and recruitment are discussed.
Immunological importance of the second gut segment of carp. III. Systemic and/or mucosal immune responses after immunization with soluble or particulate antigen
Authors: Rombout J. H. W. M. , van den Berg A. A. , van den Berg C. T. G. A. , Witte P. , Egberts E.
Published: January 2006

Mucosal and systemic (serum) immune responses were studied after oral, anal or intramuscular (i.m.) immunization with particulate (Vibrio anguillarum) or soluble (ferritin) antigen. Antigen specific antibodies were found by ELISA in skin mucus after repeated oral or anal administration of bacteria, but not after immunization with ferritin. Daily feeding with bacteria did not give detectable antibodies in serum, while regular oral administration of ferritin resulted in an increase of specific antibodies during the first 3 weeks. From that time immunosuppression was observed, as the antibody titre decreased despite the continued ferritin feeding. Immunosuppression was also found after a second anal intubation or i.m. injection with ferritin, independent of the route of priming (i.m. or anal). On the contrary, a second anal intubation of bacteria resulted in a secondary serum response. These results combined with those reported in Parts I and II of the study indicate an important immunological role for the second gut segment. Because mucosal as well as serum responses can be obtained by anal immunization with bacteria, the significance for oral vaccination is discussed.
The effects of eight trace metals in acid soft water on survival, mineral uptake and skeletal calcium deposition in yolk‐sac fry of brown trout, Salmo trutta L.
Authors: Reader J. P. , Everall N. C. , Sayer M. D. J. , Morris R.
Published: January 2006

Recently hatched fry of brown trout were exposed to each of eight trace metals (Al, Cd, Cu, Fe, Mn, Ni, Pb, Zn) and to a mixture of all eight, at concentrations typical of soft acid waters, in flowing artificial soft water medium at pH 4·5 and 6·5, for 30 days. At pH 4·5, in the absence of trace metals, net uptake of Ca, Na and K and skeletal calcification were impaired but mortalities were low (10%). At pH 4·5, in the presence of Al, Cu, Pb and Zn individually and the mixture, mortalities were high (87–100%). Cd, Fe, Mn and Ni at pH 4·5 each caused some mortalities (17–43%) and impaired skeletal calcification. At pH 6·5, each of Al, Cd, Cu, Fe, Mn, Pb and the mixture of metals impaired net Ca uptake and (except Al, Fe and Pb) skeletal calcification. Net K uptake was impaired by Al and by the mixture, and less severely by Cu and by Fe. Net Na uptake was impaired by Al and by the mixture, and less severely by Fe and by Mn. The role of trace metals other than Al in fisheries’decline in soft acid waters is discussed.
The response of trout red cells to adrenaline during seasonal acclimation and changes in temperature
Authors: Milligan C. L. , Graham M. S. , Farrell A. P.
Published: January 2006

Adult rainbow trout were acclimated to three different temperature and photoperiod regimes: 17°C, 14 h light: 10 h dark (summer); 7° C, 14 h light: 10 h dark; and 5° C, 8 h light: 16 h dark (winter). Blood was collected from these fish after 40 days acclimation, and the response of red blood cells to in vitro adrenergic stimulation was assessed. To examine potential seasonal variations in endogenous levels of circulating catecholamines, plasma levels of adrenaline (Ad) and noradrenaline (NAd) were measured at rest and after exercise. At rest, there were no differences between groups in plasma levels of either Ad or NAd, but, after exercise, the pattern of catecholamine elevation differed. In fish acclimated to 17 and 7° C in summer, Ad and NAd increased by about the same amount (10–15 times). In fish acclimated to 5° C in winter, NAd increased about three‐fold, compared to the near 50‐fold increase in Ad levels. Whether this difference between groups can be attributed to seasonal influences is unclear. At both low (0·5%) and high (2%) PCO2, adrenergic stimulation (2 × 10‐7 M Ad) of trout red cells in vitro led to a significant reduction in MCHC (mean cell [haemoglobin]), compared to non‐stimulated cells. However, only at the high PCO2 were pHe and red cell pHi significantly different from those in the non‐stimulated cells: the latter was higher and the former lower in the stimulated cells. There were no differences in the response of red cells to adrenergic stimulation between groups of fish. Under the conditions of the present study no influence of season and/or temperature on the in vitro response of trout red cells to adrenergic stimulation was shown.
Respiratory responses of Oreochromis niloticus (Pisces, Cichlidae) to environmental hypoxia under different thermal conditions
Authors: Fernandes M. N. , Rantin F. T.
Published: January 2006

The oxygen uptake (VO2), breathing frequency (fR), breath volume (VS.R), gill ventilation (VG) and oxygen extraction (%) from the ventilatory current of four groups of Oreochromis niloticus during graded hypoxia were measured under the following acclimation temperatures: 20. 25. 30 and 35°C. The critical oxygen tensions (PO2), determined from VO2v. PO2 of inspired water at each experimental temperature were, respectively. 19±1±3±1. 18±0±4±9, 29±7± 4±1 and 30±2± 0.6 mmHg. The fR remained nearly constant during the reductions of O2 at all the temperatures studied. VG increased discretely from normoxic levels until the PO2 was reached, below which it assumed extremely high values (17‐fold higher or more). The increases observed in VG resulted, at all the acclimation temperatures, in an elevation in VS.R rather than in fR. The extraction of O2 decreased gradually from normoxia until the PO2 was reached, below which an abrupt reduction of extraction was recorded, except at 35°C when fish showed a gradual reduction in extraction just below the tension of 80 mmHg.
Effects of implanted dummy transmitters on mortality, growth and tissue reaction in rainbow trout, Salmo gairdneri Richardson
Authors: Lucas M. C.
Published: January 2006

For the first time, workers in the U.K. with a Home Office licence may surgically implant transmitters into wild fish in order to track them. A laboratory study was designed to investigate the effects of intraperitoneally implanted transmitters on rainbow trout. No significant difference in mortality or growth occurred between control, sham‐implanted and implanted groups of fish over a 7‐month period. Transmitters became encapsulated by connective tissue, the composition of which is described. Three fish expelled transmitters via the body wall without subsequent mortality or morbidity. Histological evidence suggests pressure necrosis of the body wall adjacent to the tag to be the mechanism of expulsion. With good surgical procedure, intraperitoneal implantation appears to provide a suitable technique for attaching transmitters to fish, and may be preferable to existing methods for many fish.
The fish assemblage on a coralligenous shallow shelf off the Mediterranean coast of northern Israel
Authors: Spanier E. , Pisanty† S. , Tom M. , Almog‐Shtayer G.
Published: January 2006

The fish assemblage on the shallow coralligenous shelf (16‐30m depth) off Haifa, Israel was sampled using trammel nets throughout a period of 1 year. Complementary data were obtained via underwater censuses of fish on an artificial reef established later in the sampling area. Fortythree species of fish were sampled by trammel nets, 79% of which were observed also during the underwater censuses. Although fish of Red Sea origin constituted only 11.6% of the species composition in the net samples, they contributed 46.2% of the fish abundance and 40.6% of the biomass in these samples. This was supported by the finding that species of Red Sea origin contributed 64% of the abundance of large fish counted on the artificial reef. Siganus luridas, S. rivulatus and Sargocentron rubrum are the main contributors in number and biomass among fish of Red Sea origin. It is suggested that the biogenic rocky bottom of this area contains several components which are similar to biogenic habitats favoured by these benthic species in the Red Sea; this may explain the high abundance of these species in the studied area.
Dietary salt intake and its relevance to ionic regulation in freshwater salmonids
Authors: Smith N. F. , Talbot C. , Eddy F. B.
Published: January 2006

Dietary sodium intake for freshwater salmonids feeding in the wild (invertebrate diet) or in captivity (pellet diet) was calculated and compared with published branchial sodium influx values. Dietary sodium intake (mmol kg−1 per month) increases from winter minimum values of 5 and 30‐40 to reach maximum values in summer of 175 and 240 for invertebrate and pellet diet, respectively. In summer, dietary sodium intake for fish feeding in the wild was of the same magnitude as branchial sodium influx. The implications of dietary sodium intake for sodium balance in freshwater fish are discussed.
Kinetic characteristics of the sodium uptake mechanism during the development of embryos and fry of Atlantic salmon, Salmo salar L., in an improved water quality
Authors: McWilliams P. G. , Shephard K. L.
Published: January 2006

The kinetics of active sodium uptake in dechorionated embryos, yolk‐sac fry and start‐feed fry of Atlantic salmon were compared in two groups reared either in low conductivity, untreated, river water (conductivity ∼ 46 μS cm−1, pH 5.75), or in ‘improved’ river water buffered with sea water (conductivity ∼2200 μS cm 1, pH 6.56), the latter treatment often being used in commercial hatcheries to avoid problems associated with periodic acidification.

Maximal transport rate (Vmax) increased during development in both groups but was always significantly higher in embryos and fry maintained in untreated river water. Values for Km were not seen to vary during development up to 12 weeks after hatching and were not significantly different between groups, or from values reported for adult Atlantic salmon in fresh water.

The results are discussed with respect to the influence of Na+ concentrations in the perivitelline fluid of developing eggs and in the external medium surrounding fry on Vmax and Km. The ability of fry reared entirely in buffered river water to maintain sodium balance following transfer to untreated river water is also considered.
Histomorphological changes in some organs of the brown bullhead, Ictalurus nebulosus LeSueur, following short‐ and long‐term exposure to copper
Authors: Benedetti I. , Albano A. G. , Mola L.
Published: January 2006

The effects of copper in solution on Icfalurus nebulosus was studied by means of acute short‐term bioassay and long‐term bioassay. Histomorphological and histochemical tests were performed on skin. liver, gills, gut and kidney; enzymatic tests were also performed on the liver.

Morphological changes of skin. liver and gills are described. The results of the histoenzymatic tests on the liver agree with the histological findings and confirm a mild onset and slow evolution of liver distress.
Mitochondrial DNA in the Atlantic cod, Gadus morhua: lack of genetic divergence between eastern and western populations
Authors: Smith P. J. , Birley A. J. , Jamieson A. , Bishop C. A.
Published: January 2006

Mitochondrial DNA variation was examined in two populations of Atlantic cod from the North Sea and the Grand Banks of Newfoundland. Eight restriction enzymes revealed no major genetic difference between these eastern and western populations. These results are discussed in relation to earlier electrophoretic studies on this species.
Ecology of the acanthocephalan Sclerocollum rubrimaris Schmidt and Paperna, 1978 (Rhadinorhynchidae: Gorgorhynchinae) from wild populations of rabbitfish (genus Siganus) in the northern Red Sea
Authors: DIamant A.
Published: January 2006

The abundance, host relationships and microhabitat of Sclerocollum rubrimaris Schmidt & Paperna. 1978 (Rhadinorhynchidae: Gorgorhynchinae) were investigated in wild populations of the herbivorous rabbitfish (Siganus spp.) from the Gulf of Eilat, northern Red Sea. Siganus rivulatus (Forsskål, 1775) and S. argenteus (Quoy & Gaimard, 1825), judging by the high infection prevalences, are the primary definite hosts, whereas S. luridus (Ruppell, 1828) was only rarely infected and thus regarded as an accessory host. Overdispersion of S. rubrimaris suprapopu‐lations was greatest in S. rivulatus. Juvenile worms occurred year‐round, but enhanced recruitment was evident in both host populations between February and July. A high parasite abundance observed during spring (March‐May) was correlated with an extensive period of pre‐spawning algal grazing by the host fish. In S. rivulatus, parasite abundance increased with increasing host size, whereas in S. argenteus it was highest in young hosts, and decreased in larger fish. The variability of infection patterns in the three rabbitfish species probably stems not only from parasite specificity but also from the different habitats, feeding habits and diet preferences. Sclerocollum rubrimaris has a restricted host range and is not known to infect other herbivorous coral reef fish. The main region of attachment of S. rubrimaris is the anterior 5–25% of the gut in both S. rivulatus and S. argenteus, and the mean position of immature worms is significantly more posterior than that of sexually mature individuals.
The deposition and mortality of the eggs of the Baltic herring Clupea harengus membras L., on different substrates in the south‐west archipelago of Finland
Authors: Rajasilta M. , Eklund J. , Kääriä J. , Ranta‐Aho K.
Published: January 2006

The environmental factors affecting the deposition and mortality of the eggs of the spring‐spawning Baltic herring were studied in the inner Archipelago Sea of south‐western Finland. On four spawning grounds, 27 study squares (area 1 m2) were surveyed by divers. In each square, one quantitative egg sample was taken and the following data were recorded: depth, temperature, bottom quality of the square and under the eggs, egg substrate, cover (%) of plants and/or the bivalve Mytilus edulis, and the heterogeneity of the environment, expressed as the total number of all bottom materials, plants and Mytilus found in the square.

Eggs were found in the depth zone of 1–4 m. Their density ranged from 6000 to 2·3 millions of eggs per square metre. Egg number had a significant negative correlation with both depth (r=‐0·545, P<0·01, d.f. = 25) and temperature of the sea water (r=‐0.479,. P<0·01,d.f. = 25), and a positive correlation with the total cover (%) in the squares (r= 0·375, P < 0·05, d.f. = 25).

The highest numbers of eggs were found on Cladophora glomerata, which the most preferred spawning substrate of those present. Mortality of the eggs varied according to the substrate. In eggs attached to Cladophora, Potamogeton and Mytilus, the proportion of dead eggs was 0.15·5%; in those attached to red algae it was significantly higher (Furcellaria, 5·0–63·2%; Phyllophora, 0–95·2%).
The food of herring, Clupea harengus, in the North Sea, 1983–1986
Authors: Last J. M.
Published: January 2006

The stomach contents of 5762 herring caught during North Sea trawl surveys in February 1983, February 1984 and February, May and August 1986 were analysed. The principal prey organisms were the copepods Calanus finmarchicus and Temora longicaudata, but Euphausiacea and the post‐larval stages of Ammodytes spp. and clupeoids contributed a large percentage of the weight. Fish eggs were eaten, chiefly those of plaice, Pleuronectes platessa, but not in large numbers.
Effects of exogenous thyroxine or prior exposure to raised water‐flow on the downstream movement of hatchery‐reared Atlantic salmon smolts
Authors: Youngson A. F. , Hansen L. P. , Jonsson B. , Naesje T. F.
Published: January 2006

Administration of thyroxine to hatchery‐reared Atlantic salmon smolts raised blood serum thyroxine levels 24 h later to exceed those in controls. Treatment also slowed downstream movement when smolts were released into a stream above a fish trap. The descent of smolts released immediately after being challenged with high‐water flows for several hours was also slowed, and proportionately fewer challenged fish than controls were captured at the fish trap. These findings were consistent in each of two years. Only in one year, however, could flow‐challenge be shown to raise endogenous thyroxine levels in blood serum. It is concluded that exogenous thyroxine treatment and flow‐challenge before release have qualitatively similar effects on downstream movement but that this similarity is possibly not a consequence of the common effect of increased serum thyroxine raised either exogenously or from the thyroid system itself.
Observations on eosinophilic granule cells in peritoneal exudates of eels, Anguilla amtmlis
Authors: Hine P. M. , Wain J. M.
Published: January 2006

Eosinophilic granule cells (EGC) are reported among peritoneal exudate cells (PEC) of unstimulated and carrageenan‐, zymosan‐, latex‐ and Aeromonas hydrophila‐stimulated eels, Anguilla australis. At the light microscopy level EGC are large (< 50 μm diameter) and have strongly to moderately basophilic cytoplasm, eosinophilic granules, and often striated colourless cytoplasmic inclusions. Ultrastructurally, the cytoplasm is rich in ribosomes, and contains characteristic granules, parallel tubular structures 46–50 nm in diameter, and parallel rod‐like arrays (PRLA) 14–15 nm in diameter that are angular or hexagonal in cross section. EGC contain granule‐associated, partially or completely cyanide inhibited, but azide and aminotriazole resistant, peroxidase, acid phosphatase, esterases and weak cytoplasmic periodic acid‐Schiff positivity. PRLA lack enzyme content. A few (< 10%) unstimulated and carrageenan‐ and zymosan‐stimulated EGC contain granule‐associated and diffuse β‐galactosidase, and EGC in eels injected i.p. with filtered carrageenan‐stimulated PEC supernatants show heterogeneity in glucosaminidase content.
Micro‐anatomy of the pectoral fin in blennies (Blenniini, Blennioidea, Teleostei)
Authors: Brandstätter R. , Misof B. , Pazmandi C. , Wagner G. P.
Published: January 2006

Blennioid fishes show a highly differentiated pectoral fin, which they use to cling to the substrate. The lower part of the pectoralis, comprising about four to six fin rays, forms a hook‐field with specific anatomical features: (1) the rim of the fin web has a saw‐like appearance, because it extends from the tip of a fin ray to the shaft ofthe upper of two neighbouring fin rays, (2) the outer half of the bony fin ray carries a lepidotrichal cord composed of fibrocytes, collagen, elastic fibres and acidic GAGS, (3) the epidermis overlying the lepidotrichal cord is differentiated in terms of cyto‐architecture and forms a conspicuous cuticle. The upper part of the pectoral fin does not show any obvious specializations and is used for swimming and undulation. The vascularization of the fin originates from a stem vessel which gives rise to five branches, each supplying two or three neighbouring fin rays. Each fin ray is accompanied by a single arterial vessel at its upper edge. No vessels are found in the space between the bony fin ray halves. The morphology of the shoulder girdle and pectoral fin shows only little variation among the four species of Blenniini studied. Most remarkable is the fusion of the coracoid with the cleithrum, loss of one element of the suspensorium and the absence of branched fin rays. The possible relevance of the Blennioid pectoral fin as a model for the origin of morphological novelties in connection with functional specializations is discussed.
The annual reproductive cycle of pike, Esox lucius L., in two Scottish lakes
Authors: Treasurer J. W.
Published: January 2006

Histological changes in the ovaries of pike from two shallow, adjacent, Scottish lakes are described and related to a macroscopic scale of maturity stages and to changes in gonad weight. There was no evidence of pre‐ovulatory degeneration although occasional residual oocytes were present in spent ovaries. The gonadosomatic index (GSI) was high in males from October to March, and in females it increased through the winter months to a maximum immediately prior to spawning. Maximum ovarian weight was 8.3–9.0% of total body weight compared with only 0.9–1.1% for testes. These GSIs were low compared with other reports for the British Isles, suggesting lower reproductive output. Spawning occurred in the first two weeks of April at a water temperature of 6.0–7.5° C. Fecundity was described from a regression of egg number (F) on fork length (f.l.): log10F= ‐1.51 + 3.33 log10 f.l. (cm). Mean egg diameter after preservation varied from 1.1 to 2.4 mm over the size range examined. Males were mature at age 2 at a length of ≥ 27 cm, while females first spawned at age 3 at a length of ≤ 28 cm, although a minority were mature at age 2. The sex ratio was 1.2 males: 1 female at Kinord and 1.4 : 1 at Davan. Greater egg production at Davan, 50 678 ha−1, compared with Kinord, 33 557 ha−1, was due to higher individual fecundity‐at‐age resulting from better growth.

Fecundity (19.29 × 103 calculated for a pike of 55 cm F.L.), relative fecundity of only 10–24 eggs per gram wet weight of adult, and GSI values were low compared with pike in North America and Eurasia. Food supply may restrict reproductive output of pike in Lochs Kinord and Davan. The abundance ratio of predator: prey is high with the main prey species, perch, present in low numbers, and the only alternative species is eel in these simple fish communities.
Do fish lymphocytes secrete interferon‐γ?
Authors: Graham S. , Secombes C. J.
Published: January 2006

Macrophage activating factor (MAF)‐containing supernatants, generated by mitogen (Con A/PMA) stimulation of rainbow trout leucocytes, were found to confer viral resistance (interferon, IFN, activity) on a rainbow trout epithelial cell line challenged with infectious pancreatic necrosis virus. Both the MAF and IFN activities co‐eluted by HPLC size exclusion chromatography and showed similar sensitivities to acid (pH 2), temperature (60° C) and trypsin. The mode of induction of this IFN, its acid and temperature sensitivity and its possible MAF activity suggest that fish leucocytes can secrete an IFN‐γ like molecule.
Thin‐blooded Antarctic fishes: a rheological comparison of the haemoglobin‐free icefishes Chionodraco kathleenae and Cryodraco antarcticus with a red‐blooded nototheniid, Pagothenia bernacchii
Authors: Wells R. M. G. , Macdonald J. A. , DiPrisco G.
Published: January 2006

The icefishes (family Channichthyidae) comprise a unique group of teleost fishes endemic to Antarctic and sub‐antarctic seas. All members of the family totally lack haemoglobin.

Haematological parameters and viscosity were determined for blood from 11 specimens of two channichthyid species (Chionodraco kathleenae Regan, 1914; Cryodraco antarcticus Dollo, 1900), and 14 specimens of a red‐blood Antarctic nototheniid species (Pagothenia bernacchii (Boulenger, 1902)), captured near the Italian research station at Terra Nova Bay, Ross Sea, Antarctica. Channichthyid blood contained only a small number of non‐pigmented cells (10 000‐40 000 cells μI−1, depending on species) in contrast to nototheniid blood (360 000‐450 000 cells μI−1 in unstressed specimens).

Blood viscosity was measured by cone plate viscometry over a range of shear rates (11.3‐450s −1), at six temperatures between – 1.8°C and + 15°C. At the ambient Antarctic seawater temperature of – 1.8° C, and at low shear rate (22.5 s−1), the viscosity of channichthyid blood was relatively low (3.99 ± 0.40 cP) compared with blood taken from unstressed P. bernacchii, which was about 25% more viscous (4.91 ± 0.59 cP). The viscosity of channichthyid blood was almost independent of shear rate, approximating an ideal Newtonian fluid, while the viscosity of nototheniid blood was much more dependent upon both shear rate and temperature, increasing sharply at low shear rates and low temperatures.

Viscosity of nototheniid blood varied with haematocrit, which was in turn strongly influenced by stress. Blood samples taken from P. bernacchii under moderate stress induced by handling during acute caudal venepuncture had haematocrit values in the range 15–20% and viscosities of 8‐l0cP, while undisturbed specimens sampled through a venous cannula yielded haematocrits of 8–10%. The viscosity of nototheniid plasma did not differ significantly from that of channichthyid whole blood or channichthyid plasma. The higher viscosity of nototheniid blood is attributable to cell content, and in stressed specimens possibly also to adrenergic swelling of erythrocytes.

The absence of erythrocytes in channichthyid blood avoids the great increases in viscosity which are induced in corpusculate blood by sub‐zero seawater temperatures.
Growth dynamics of caudal and pectoral fin muscle fibres in a carangid, Caranx malabaricus (Cuv. & Val.), and their possible relation with somatic growth
Authors: Kundu R. , Lakshmi R. , Mansuri A. P.
Published: January 2006

The growth dynamics of red, pink and white fibres of the caudal and pectoral fin muscles are described in Carans malabaricus (Cuv. & Val.) in relation to their somatic growth. In all three fibre types growth occurred by an increase in fibre number and diameter in small size classes of fish and by an increase in diameter only in larger fish. The growth dynamics of the three fibre types were similar to those of the myotomal muscle fibres and paralleled the somatic growth pattern of this fish.
Geographic variation in life–history strategy of female roach, Rutilus rutilus (L.)
Authors: Vøllestad L. A. , L'Abée‐Lund J. H.
Published: January 2006

Variation in growth rate, age at maturity, reproductive life span and reproductive investment was investigated in females only in seven populations of roach, Rutilus rutilus, in Norway. The growth rates of mature female roach were low, varying for most populations between 10 and 14 mm year.1 At the most northern locality the growth rate was only 5.6 mm year1. Individual fecundity and gonadosomatic index (GSI) varied unsystematically between populations, but it was evident that the population with the lowest growth rate also had the lowest individual fecundity and GSI. Egg weight also varied between populations, the most northern population had a medium egg weight, thus, in harsh climatic conditions egg number is sacrificed for a relatively high egg weight. We found no further evidence for a trade‐off between egg number and egg size. Fecundity increased with length in all populations, whereas the variation in egg size and GSI for most populations did not covary with length or age. This fact, together with the high age at maturity in all populations and the long reproductive life spans supports the bet‐hedging theory of life‐history evolution. This is further supported by the fact that we did not find any correlation between the growth rates and the different descriptors of fitness.
Gastric evacuation of three food types in the black and yellow rockfish Sebastes chrysomelas (Jordan and Gilbert)
Authors: Hopkins T. E. , Larson R. J.
Published: January 2006

The evacuation patterns of shrimp, crab and fish from the stomachs of black and yellow rockfish, Sebastes chrysomelas, were examined by feeding meals of known size and measuring the amount remaining after various post‐prandial intervals. Linear, square‐root, exponential, power exponential, logistic and Gompertz models (the latter two with unrestricted lower asymptotes, or with lower asymptotes restricted to 0% food remaining) were fitted to the wet weight, dry weight and volume of food remaining in the stomach as a function of post‐prandial time. Evacuation patterns ranged from steeply concave (fish wet weight, dry weight, volume, shrimp dry weight), to linear (shrimp wet weight, crab dry weight), to highly convex with lag phases of up to 30 h (crab wet weight, crab and shrimp volume). Friability, the ease with which a food item is fragmented in the stomach, may be an important factor in determining evacuation patterns. The evacuation of a crab meal by tagged, free‐ranging S. chrysomelas in the field was not significantly different from that of S. chrysomelas held in the laboratory.
Comparison of digenean faunas of sillaginid fishes from inshore and offshore waters of Visakhapatnam Coast, Bay of Bengal
Authors: Sujatha K. , Madhavi R.
Published: January 2006

The sillaginid fishes of Visakhapatnam Coast, Bay of Bengal, are found to be hosts for 16 species of digeneans of which seven are adult digeneans belonging to families Opecoelidae, Zoogonidae and Hemiuridae and nine are larval digeneans representing families Bucephalidae, Heterophyidae, Cryptogonimidae, Acanthocolpidae, Hemiuridae and Didymozoidae. The digenean fauna of sillaginid fishes from shallow coastal waters (< 10 m depth) and deeper offshore waters (30–50 m depth) are compared and results are discussed in the light of existing information on the migratory movements of different species of sillaginids and their occurrence in coastal or offshore waters. The usefulness of metacercariae of these fishes as ‘biological tags’ is considered.
Use of dual‐beam acoustic technique for detecting young whitefish, Coregonus sp., juveniles: first experiments in an enclosure
Authors: Ponton D. , Meng H. J.
Published: January 2006

We tested the possibility of using a high‐frequency, BioSonics, dual‐beam, acoustic system with an upwards‐looking transducer to detect very young whitefish, Coregonus sp., juveniles. These first experiments were conducted in an enclosure with 100 fish (20–30 mm total length).

Observations over 24‐h periods showed wide variations of the fish vertical distribution (> 5 m) and two typical aggregation patterns in near‐surface waters at dawn and dusk. No direct relationship was found between light intensity and distribution of the fish during the day.

The mean target strength of young whitefish juveniles was found to be – 56 dB when fish were staying near the surface and – 63 dB as they were moving up‐ or downwards.
The influence of salinity on water balance in 0‐group flounders, Platichthys flesus (L)
Authors: Hutchinson S. , Hawkins L. E.
Published: January 2006

The water balance of 0‐group flounders was investigated in a range of static [0–100% sea water (SW), 100%≡ 34%‰] and cycling salinities (2–98% SW, 12 h 25 min period). The permeability coefficients of these juvenile fish were found to be higher than those quoted for adults. The permeability of juveniles in fixed salinities decreased with increased salinity whereas animals in the tidally cycling regime showed permeability changes that were directly proportional to the ambient salinity. However, comparison of the two groups showed that animals in a cycling salinity regime were less permeable to water than animals acclimated to fixed salinities. Drinking and urine production rates fluctuated within a tidal salinity regime, and 0‐group flounders were found to modify their water permeability, urine production and drinking rates simultaneously, so maintaining their blood osmotic concentration and total water content within narrow limits throughout the range of salinities.

The relevance of measurements made in fixed and tidally cycling salinities to water regulation under natural estuarine conditions is considered.
Desert fishes: an interdisciplinary approach to endangered species conservation in North America
Authors: Pister E. P.
Published: January 2006

The habitat degradation and species endangerment that preceded and accompanied the North American environmental movement in the late 1960s and early 1970s found the conservation community ill‐prepared. Protective legislation and basic research necessary for structuring recovery efforts did not exist. Desert aquatic communities were among the first to need attention, and an interdisciplinary effort was mounted in an early application of conservation biology. The history and evolution of desert ecosystem preservation are discussed, and case histories are presented that may prove helpful in other parts of the world as habitats are inexorably reduced. The role of the Desert Fishes Council in co‐ordinating efforts of research scientists and resource managers to achieve common objectives is emphasized.
Relationship between the chemical composition of aquatic macrophytes and their consumption by grass carp, Ctenopharyngodon idella
Authors: Bonar S. A. , Sehgal H. S. , Pauley G. B. , Thomas G. L.
Published: January 2006

The rate at which triploid grass carp, Ctenopharyngodon idella, consumed two plant species from different locations was measured and compared to the chemical composition of the plants. Grass carp fed on Elodea canadensis from three lakes at significantly different rates (P> 0.001), but did not eat Elodea densa from two of the sites at different rates. Feeding rate of the grass carp was positively correlated to the concentration of calcium (r= 0.976) and lignin (r= 0.946), but negatively correlated to the content of iron (r=−0.808), silica (r=‐0.934) and cellulose (r=−0.922). Multiple regression analysis revealed that calcium and cellulose content were the most important predictors of consumption rate. These experiments demonstrate that water chemistry may affect palatability and could in part be responsible for some of the discrepancies in grass carp consumption rate and preference studies.
Ontogeny of IgM‐producing cells in the lymphoid organs of rainbow trout, Salmo gairdneri Richardson: an immuno‐ and enzyme‐histochemical study
Authors: Razquin B. E. , Castillo A. , López‐Fierro P. , Alvarez F. , Zapata A. , Villena A. J.
Published: January 2006

The ontogenetic development of IgM‐containing cells is described as demonstrated by immunoperoxidase staining with a mouse anti‐trout IgM monoclonal antibody and the differentiation of enzyme‐histochemical markers in the non‐lymphoid cells forming the stroma of the thymus, spleen and kidney of the rainbow trout. The first lymphoid cells staining with the monoclonal antibody occurred at day 4‐5 after hatching in the renal lympho‐haemopoietic tissue. By 1 month after hatching IgM‐positive cells also appeared in the spleen and thymus. Enzyme‐histochemical demonstration of the alkaline and acid phosphatase and non‐specific σ‐naphthyl acetate esterase enzymatic activities in the non‐lymphoid cells indicated that a certain degree of maturation of the cellular stroma of the developing lymphoid organs of trout was reached before or at the time when IgM‐expressing cells could be observed. The relationships of the stromal components of the various lymphoid organs to the development of IgM‐positive cells, and the possible role of the renal lympho‐haemopoietic tissue as a primary lymphoid organ for B‐cell differentiation in the trout are discussed.
Histochemical characterization of myotomal muscle in the roach, Rutilus rutilus (L.)
Authors: Kilarski W.
Published: January 2006

A histochemical study of the myotomal muscles in the roach revealed three main muscle regions: red, intermediate and white. These were distinguished on the basis of glycogen content, succinate dehydrogenase (SDH), and myofibrillar ATPase (mATPase) activity. Except for the red fibre region, none of these described regions is homogeneous. The principal new findings are the toniclike fibre, the presence of a transitional zone with two fibre types, and the mosaic organization of the white fibre region. The significance of this type of myotome architecture in relation to the locomotion of the species is discussed.
The development of regular seasonal habitat shifts in a landlocked Arctic charr, Salvelinus alpinus L., population
Authors: Näslund I.
Published: January 2006

Parts of the Arctic charr population of the subarctic Lake Visjön in north‐west Sweden migrate upstream during the spring to two small, recently eutrophied and very productive lakes. Large repeat migrants arrive first, followed by young first‐time migrants. Charr in the small lakes grow more rapidly than those resident in L. Visjön. In early September mature fish leave the lakes, followed by immature fish later in September and in October. Overwintering and spawning takes place in L. Visjön. Migratory females attain maturity at age 4 years and resident females at age 6 years. The migrant fish return annually until they are 5–6 years old. This limit may be due to reduced relative growth benefits of the habitat shift for larger individuals. The rapid development of these regular habitat shifts could be explained by an internally fixed exploratory behaviour in these Arctic charr that makes the detection and utilization of distant feeding resources possible. Migrants will possess a considerably higher fitness, if survival rates for migratory and resident fish are equal.
Fine‐structural study of leucocytes in the goldfish, Carassius auratus
Authors: Fujimaki Y. , Isoda M.
Published: January 2006

An electron microscopic study was performed on leucocytes from circulating blood of the goldfish. The leucocytes were divided into eight types: neutrophil, eosinophil, large granular leucocyte (LGL), medium‐sized granular leucocyte (MGL), small granular leucocyte (SGL), fine granular leucocyte (FGL), lymphocyte, and monocyte. In this report the thrombocyte was excluded from leucocytes, and LGL, MGL, SGL and FGL were tentatively classified based on the size of intracytoplasmic granules possessed by each cell. The existence of goldfish monocytes was electron microscopically demonstrated for the first time in the present report.
Factors in habitat partitioning in Pseudotropheus aurora (Pisces: Cichlidae), an introduced species to a species‐rich community of Lake Malawi
Authors: Hert E.
Published: January 2006

The territorial behaviour of a small rock‐dwelling cichlid, Pseudotropheus aurora, was studied at Thumbi Island West at the southern end of Lake Malawi. P. aurora is one of several species that have been introduced to an already diverse fish community. Many of the endemic and introduced species are highly territorial. The coexistence of an introduced territorial species within a speciesrich community of other territorial species is examined. Territories from which P. aurora individuals were removed were invariably re‐occupied by conspecifics. Similarly, when all territories of a certain area were emptied of all territory owners of any existing species, the former P. aurora territories were re‐occupied by conspecifics.

The possible roles of site specificity, competitive exclusion and behaviourally transmitted traditions regarding territories are discussed.
The ontogeny of drinking in the rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: Tytler P. , Tatner M. , Findlay C.
Published: January 2006

Drinking was measured by the rate of uptake of tritiated dextran in fresh water by the alevins and fry of rainbow trout at various stages of development during a 40‐day post‐hatch period. Drinking increased almost S‐fold during the initial 16 day yolk‐sac stage. Drinking rate increased most between 16 and 23 days, the transitional period between yolk‐sac absorption and first feeding. The maximum weight‐specific drinkingrateof 3.24μlg−1 h−1 recorded for 40‐day‐old fry was higher than previously recorded for adults. Abrupt transfer from an adaptation temperature of 10 to 19° C increased drinking significantly (Q10= 1.2), but sudden transfer to 1 1‰ salinity sea water caused a substantial fall in drinking rate in 23‐day fry. A 24‐h period of adaptation to 1 1‰ and 15‰ salinity restored drinking to a rate similar to that in fresh water. The water drunk by 31‐day fry fed to satiation was initially higher than by unfed fry, but drinking rates subsequently fell below the control level. The results are discussed in terms of osmoregulation and the uptake of dissolved or suspended substances by the intestinal tract for the purpose of immunization.
Social dominance and body size in Atlantic salmon parr, Salmo solar L.
Authors: Huntingford F. A. , Metcalfe N. B. , Thorpe J. E. , Graham W. D. , Adams C. E.
Published: January 2006

Dominance relationships between pairs of Atlantic salmon parr of known size were assessed at various times during their first year of life. In tests conducted between first feeding and early July, the larger of two fish was dominant in only 54% of pairs, regardless of the magnitude of the size difference between the fish. In September, there was a stronger association between size and status, especially in pairs with a large size differential, where the dominant was larger in 72% of cases. In groups of parr tested in April of the following year, there was no relationship between size and status, the larger of two fish being dominant in 48% of cases, regardless of the magnitude of the size differential. This result suggests that status in early social interactions may depend on behavioural properties rather than size and that the larger size of dominant fish reported in a number of salmonids might be a consequence and not a cause of high status.
The gonopodia of the fishes of the tribe Cnesterodontini (Cyprinodontiformes, Poeciliidae)
Authors: Chambers J.
Published: January 2006

The South American livebearing toothcarp tribe Cnesterodontini is discussed, and a description of the gonopodium of each of the species of the four genera is given, together with a figure and a synonymy.
A quantitative and histochemical study on melano‐macrophage centres in the spleen of the teleost fish Diplodus annularis L.
Authors: Micale V. , Perdichizzi F.
Published: January 2006

The incidence and histochemical features of melano‐macrophage centres in the spleen of the teleost fish D. annularis were studied with respect to starved and fed fish. Tissue catabolism following complete starvation appears to induce formation of new centres containing melanin and lipofuscin pigments. However, a change in the amount of melano‐macrophages was also recorded in fed fish, suggesting that some other factor(s), internal to fish, may affect the presence of such structures within the spleen of D. annularis.
Zinc and copper in fish from natural waters and rearing ponds in Northern Italy
Authors: Carpenè E. , Cattani O. , Serrazanetti G. P. , Fedrizzi G. , Cortesi P.
Published: January 2006

Zinc and copper were detected in several tissues of fresh and saltwater fish. Liver concentrations varied widely, with respect to the storage and detoxication functions of the organ. In muscular tissues the two metals are linked to aerobic metabolism being higher in the heart and lower in the white muscle. High levels of zinc were found in the female gonad, while in the brain zinc has been shown to be more constant and possibly regulated better than copper. In sea bass supplemented with artificial diets no correlation was found between the metal content in the diet and that of the tissue. In goldfish attempts using gel filtration to isolate specific metal binding proteins of low molecular weight gave negative results, the metals were mostly bound to ligands excluded from the gel.
Karyotypic study of some species of family Mochokidae (Pisces, Siluriformes): evidence of female heterogamety
Authors: Agnèse J.‐F. , Oberdorff T. , Ozouf‐Costaz C.
Published: January 2006

Nine mochokid species, Hemysynodontis rnembranaceus, Synodontis bastiani, S. budgetti, S. courier;, S. filamentosus, S. orellifer. S. schall. S. sorex. S. violaceus, were investigated to determine their karyotype. Like many of the studied siluriforms, they were shown to possess 2N=54 or 2N=56 chromosomes, with a fundamental number varying from 95 to 102. In addition, our study revealed the existence of heteromorphic chromosomes in all the studied females of each species. These findings are discussed in relation to chromosome evolution within the siluriforms, and to differentiation of sex chromosomes in fishes.
Conflict and co‐operation in White Cloud Mountain minnow schools
Authors: Magurran A. E. , Bendelow J. A.
Published: January 2006

Schooling fish do not always behave co‐operatively, and conflict is particularly evident when individuals compete for limited resources. In White Cloud Mountain minnows, Tanichrhys albonubes, aggression is associated with the defence of potential spawning sites. Agonistic encounters between males are more prevalent when available habitat is reduced and when the number of spawning sites (patches of weed) is restricted. Conversely, competition diminishes when the fish are in a potentially threatening situation, e.g. when they are exploring a new environment.
The number of generations in freshwater monogeneans per year
Authors: Gerasev P. I. , Starovoitov V. K.
Published: January 2006

It seems that the monogenean Ancyrocephalus paradoxus inhabiting the zander Stizostedion lucioperca (L.) has three generations per year in the Kurish Bay of the Baltic Sea. Diplozoids of cyprinids in the same bay have only two generations. There is evidence that temperature is the chief factor determining the number of generations in Monogenea; but there are also data showing that an increase in abundance of some Monogenea takes place at low temperatures and during congregation of fishes. There is another opinion that sex hormones offish influence the development of Monogenea. However, the appearance of the third generation during winter and early spring is not consistent with this.