bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative effects of long‐term hypoxia on growth, feeding and oxygen consumption in juvenile turbot and European sea bass
Authors: Pichavant K. , Person‐Le‐Ruyet J. , Bayon N. Le , Severe A. , Roux A. Le , Boeuf G.
Published: April 2005

When juvenile turbot Scophthalmus maximus and sea bass Dicentrarchus labrax were fed to satiation, growth and food intake were depressed under hypoxia (3·2±0·3 and 4·5±0·2 mg O2 l‐1). However, no significant difference in growth was observed between fishes maintained in hypoxia and fed to satiation and fishes reared in normoxia (7·4±0·3 mg O2 l‐1) and fed restricted rations (same food intake of fishes at 3·2 mg O2 l‐1). Routine oxygen consumption of fishes fed to satiation was higher in normoxia than in hypoxia due to the decrease in food intake in the latter. Of the physiological parameters measured, no significant changes were observed in the two species maintained in hypoxia. This study confirms the significant interaction between environmental oxygen concentrations, feeding and growth in fishes. Decrease in food intake could be an indirect mechanism by which prolonged hypoxia reduces growth in turbot and sea bass, and may be a way to reduce energy and thus oxygen demand.
The effect of shoal size on patterns of body colour segregation in mollies
Authors: Bradner J. , McRobert S. P.
Published: April 2005

Individual white and black mollies Poecilia latipinna spent significantly more time near the larger group when given the choice between two shoals of similar colouration to themselves. When given the choice between a large and a small shoal of dissimilar colouration to themselves, black test fish spent significantly more time with the larger shoal while white test fish showed no preference for either group. Both white and black mollies chose the smaller of two shoals when given the choice between a large dissimilarly coloured shoal and a small similarly coloured shoal. The results indicate that mollies actively discriminate between shoals on the basis of both body colour and shoal size. However, body colour segregation appears to have a stronger influence on shoal choice.
A method for tracking the behaviour of mature and immature salmon parr around nests during spawning
Authors: Armstrong J. D. , Einum S. , Fleming I. A. , Rycroft P.
Published: April 2005

A remote monitoring system was developed to provide information on the behaviour of mature and immature Atlantic salmon Salmo salar parr at nests during the spawning season. An octagonal passive integrated transponder (PIT) detector (0·865 m maximum diameter) designed to surround nests of Atlantic salmon was used to identify individual salmon parr present at 38 spawning events in three circular spawning channels. The range of the detector for PIT tags presented in the optimum orientation was 2·4 cm (range between tags 1·7–3·0 cm). Using a sub‐sample of 20 spawnings, the mean efficiency of the detector (number of fish passes registered relative to number of passes observed on video) was 70·5% (range 32‐100%). There were no significant effects of time from spawning, total number of registrations, body size or maturity status (mature or immature) on efficiency. However, fish were more likely to be detected entering nests than leaving, as departures were more rapid and higher in the water column. The PIT detector did not affect the numbers of parr at spawnings or between spawning intervals of females, and allowed for the individual identification of 65 of the 72 parr observed in nests during spawning. In all cases where certain identifications were not possible and the video was of satisfactory quality, this was due to obstruction of the camera view by anadromous fish. The remote monitoring system was thus effective in identifying behavioural differences, and only one of 20 immature parr was ever detected during the period encompassing 10 min before and after spawning compared with 30 or 40 mature parr.
The effects of 17β‐oestradiol, testosterone and tamoxifen on the development of papillomata in Catostomus commersoni
Authors: Premdas P. D. , Metcalfe C. D. , Brown S.
Published: April 2005

Testosterone induced papillomata in 85% (11/13) of initially non‐papillomatous white suckers Catostomus commersoni and increased papillomata growth in 100% (16/16) of initially papillomatous suckers. 17β‐oestradiol induced papillomata in 83% (10/12) of initially nonpapillomatous suckers and increased papillomata growth in 100% (16/16) of initially papillomatous suckers. Less than 29% (4/14) of white suckers injected with tamoxifen developed papillomata, while complete papillomata regression was observed in 71% (10/14) of initially papillomatous suckers. In control groups 59% (27/46) of suckers either retained or developed papillomata and 27% (6/24) of suckers exhibited tumour regression. Protein kinase C (PKC) activity was significantly depressed and ornithine decarboxylase (ODC) activity was significantly elevated in steroid‐treated papillomata v. normal lip epidermis. ODC activity was significantly depressed in tamoxifen‐injected, regressing papillomata. There were no significant differences in plasma oestrogen and testosterone levels between papillomatous and nonpapillomatous female fish from a site contaminated with persistent organic chemicals and an uncontaminated reference site. Similarly, no significant differences in testosterone and 11‐ketotestosterone levels were observed between papillomatous and non‐papillomatous male fish.
Effects of Ligula intestinalis on habitat use, predation risk and catchability in European minnows
Authors: Museth J.
Published: April 2005

The frequency of infection with Ligula intestinalis (Cestoda) in European minnow Phoxinus phoxinus, in a subalpine lake in Eastern Norway, did not differ between vegetated shoreline, exposed shoreline and non‐vegetated localities >50 m from the shoreline. There was no difference in the vertical distribution of infected and uninfected individuals. The frequency of infection was higher among minnows in brown trout Salmo trutta stomachs than among those obtained by gillnets and minnow traps, suggesting that brown trout selectively preyed on infected minnows. Prevalence of infection decreased with increasing fish size, probably due to selective mortality among parasitized individuals. Within a given length‐class, minnows captured by different sections of multi‐mesh gillnets showed a significant increase in the frequency of infection with increasing mesh‐size. Apparently, parasitized individuals had a higher catchability in gillnets due to increased girth caused by the plerocercoid in the body cavity. This may partly explain why the observed prevalence of infection was several times higher among minnows captured by gillnets than by minnow traps.
Volume regulation by red blood cells from brown trout
Authors: Cooper A. , Taylor E. W. , Wang T.
Published: April 2005

Regulatory volume decrease, following physical swelling of red cells from brown trout Salmo trutta, was almost complete in oxygenated cells but much less in deoxygenated cells. There was a small, insignificant regulatory volume increase, following physical shrinkage. Amiloride had no effect on this response, indicating that hypertonic shrinkage did not activate the Na+/H+ exchanger. However, cell volume was increased markedly in shrunken cells by addition of noradrenaline, with deoxygenated cells showing complete recovery. These data show that the previously reported differences in volume regulation between the red cells of brown trout and rainbow trout Oncorhynchus mykiss are not present and that both species appear to have lost volume sensitivity of the Na+/H+ exchanger.
Effects of brackish water on growth, feed conversion and energy absorption efficiency by juvenile euryhaline and freshwater stenohaline fishes
Authors: Altinokand I. , Grizzle J. M.
Published: April 2005

Among six species of juvenile fishes (<6 months old), stenohaline species (channel catfishIctalurus punctatusand goldfishCarassius auratus) had their highest specific growth rate (G) and most efficient food conversion ratio (EC) and energy absorption efficiency (IE) in fresh water. Three of the euryhaline species (rainbow troutOncorhynchus mykiss, striped bassMorone saxatilisand Gulf sturgeonAcipenser oxyrinchus desotoi) had higherGand had more efficientECandIEin 3 and 9‰ salinities than in lower salinities (fresh water and 1‰). For brown troutSalmo trutta(age 3–4 months), 9‰ was above the optimum level forGandEC. However,IEfor brown trout was not significantly different at 3 and 9‰ salinities. Over the salinity range tested, channel catfish had the largest change inG,ECandIE, while changes for euryhaline species were relatively small. Although all species tested survived and grew in all treatments, salinities as low as 1‰ adversely affected the stenohaline species, and 9‰ adversely affected brown trout.
Scanning electron microscopy of the heart of the climbing perch
Authors: Munshi J. S. D. , Olson K. R. , Roy P. K. , Ghosh U.
Published: April 2005

The air‐breathing climbing perch Anabas testudineus has two ventral aortas, one directs blood through well developed anterior gill arches into the suprabranchial chambers and back to the heart and the other sends blood through rudimentary shunt‐like posterior arches and onto the systemic circulation. The sinus venosus is a thin‐walled structure and lacks myocardial trabeculae. The atrium is similar to that of other teleosts and it is traversed by numerous myocardial trabeculae. There are no sinoatrial valves, whereas the atrioventricular aperture is guarded by one pair of large wing‐shaped and two small cap‐shaped valves. The ventricle is composed only of spongy myocardium and has numerous branching lacunae extending to the epicardium. The thick‐walled bulbus arteriosus is lined with longitudinal ridges and this and the ventricular trabeculae may minimize mixing of respiratory and systemic flow while blood is passing through the heart. However, with the exception of the absence of sinoatrial valves and the ridged bulbar lumen, the heart of the climbing perch is essentially similar to that of most other non air‐breathing teleosts.
The effect of dexamethasone on the occurrence and ultrastructure of rodlet cells in goldfish
Authors: Manera M. , Simoni E. , Dezfuli B. S.
Published: April 2005

In the bulbus arteriosus of goldfish Carassius auratus a subendothelial ‘reticular space’ was comprised of reticular‐like cells, neutrophils, medium‐sized granular leucocytes, phagocytes, endothelial cells and reticulo‐endothelial cells; herein, rodlet cells (RCs) accumulated and probably matured. Four classes of RCs were identified: (1) Those occurring in the reticular space and contacting reticular‐like cells; (2) those present in the reticular space contacting reticular‐like and endothelial cells; here the RCs were discharging; (3) those occurring in the bulbar lumen anchored to lining endothelial cells or other RCs; (4) those free in the bulbar lumen. There was no significant difference in the number of RCs among control and saline‐ and dexamethasone‐treated fish, but significant differences were found in RCs' class partition and in their discharge modality. In dexamethasone‐treated goldfish class (3) RCs were almost absent (2%v. 10% of the other experimental groups), moreover 35% of the RCs developed a ‘bleb’ discharge modality rather than the most typical ‘koronenartigen konfiguration’ which developed in the vast majority (90%) of the other experimental groups.
Predation by inland silversides on an exotic cladoceran, Daphnia lumholtzi, in Lake Texoma, U.S.A.
Authors: Lienesch P. W. , Gophen M.
Published: April 2005

In the early 1990s, Lake Texoma was invaded by Daphnia lumholtzi, a large, spiny, exoticcladoceran. From April 1994 to April 1995 D. lumholtzi was most abundant in the lake in mid‐summer, after native zooplankton declined in early June. Inland silversides Menidia beryllina selectively preyed on D. lumholtzi but appeared to prefer the large native zooplankton when they were present. Daphnia lumholtzi was an important prey item for silversides during summer when large native zooplankton was scarce. The invasion of D. lumholtzi into Lake Texoma may benefit some zooplanktivorous fishes by increasing foraging opportunities during a time of low prey availability.
Sperm allocation in the three‐spined stickleback
Authors: Zbinden M. , Largiadèr C. R. , Bakker T. C. M.
Published: April 2005

Male three‐spined stickleback Gasterosteus aculeatus have a fixed amount of sperm during the breeding season because spermatogenesis is inhibited at this time. A method was developed to estimate ejaculate size in situ by removing the sperm from the male's nest. The reliability of the method was tested using known numbers of sperm. In their first mating, males ejaculated 11·64 × 106 sperm (median), representing c. 5% of the male's sperm store (median 27·88 × 107 sperm). The amount of sperm in the testes was significantly reduced in males that had mated several times (median 8·09 × 107). Additionally, ejaculate size was smaller in these experienced males (median 8·79 × 105). Heavier and larger fish invested absolutely and relatively more sperm in a mating than did lighter and smaller fish. Ejaculate size did not correlate with the mass of the egg clutch.
Visual census methods underestimate density and diversity of cryptic reef fishes
Authors: Willis T. J.
Published: April 2005

The diversity and density of small, benthic reef fishes were estimated using visual census and enclosed rotenone stations. Visual census underestimated the number of species present and the density of common species by up to 91%.
Mitochondrial DNA analysis of the geographic structure of Indian scad mackerel in the Indo‐Malay archipelago
Authors: Perrin C. , Borsa P.
Published: April 2005

Sequence analysis of a fragment of the cytochrome b gene in Decapterus russelli sampled from the Indo‐Malay archipelago revealed two distinct mitochondrial clades (mean nucleotide divergence=2·2%) whose geographic distribution was heterogeneous (Nei's GST=0·416). This pointed to a complex pattern of genetic differentiation and demonstrated limited genetic exchange between populations in this highly mobile species.
Morphogenesis of the eye of Siberian sturgeon
Authors: Rodríguez A , Gisbert E.
Published: April 2005

The most relevant changes in Acipenser baeri eye organization were detected between hatching and 5 days post hatch. At this age, the eye had an anterior chamber, lens, iris, choroid gland, scleral cartilage, cornea and a vitreous chamber lined by the retina (with two photoreceptors: rods and single cones).
A comparison of back‐calculated lengths of silver carp derived from bony structures
Authors: Johdal M. S. , Esmaeili H. R. , Tandon K. K.
Published: April 2005

Linear relationships were found between body length–scale radius, body length‐cleithrum length and body length‐urohyal length (r=0·949, 0·984 and 0·974 respectively) in silver carp Hypophthalmichthys molitrix. Out of 180 comparisons, which were made between different methods of back‐calculating length and ageing structures at ages 2‐7 years, the differences were not significant (P≥ 0·05) in 132 (73·3%) cases. There were no significant differences among different methods in older age classes and between the Fraser‐Lee method and body proportional method (BPH) at all ages. The results demonstrated that in all structures, back‐calculated lengths estimated by the scale proportional hypotheses (SPH) were less than the other methods. For scales, SPH was similar to the direct proportional method of Dahl‐Lea (DPM) but for cleithra and urohyal bones it was similar to BPH and Fraser‐Lee. As the fish increased in age, the differences between back‐calculated lengths decreased. When lengths were back‐calculated using cleithra and urohyal bones, differences between the structures at age 2 years were 17 mm from DPM, 33 mm from SPH, 37 mm from BPH and 37 mm from Fraser‐Lee, while at age 8 years mean differences were 7 mm from DPM and 8 mm from the SPH, BPH and Fraser‐Lee methods. It is suggested that the differences would be less if: (1) back‐calculated lengths are based on a large number of random samples; (2) measurements of scale radius, cleithrum length and urohyal length were precise; (3) determination of focus or origin were precise; (4) the sampling of scales were from the same row.
Sensory drive and nuptial colour loss in the three‐spined stickleback
Authors: SCOTT R. J.
Published: April 2005

Three‐spined sticklebacksGasterosteus aculeatus, from the Chehalis River drainage. Washington, U.S.A., that have lost the mosaic nuptial signal were more likely to be found in tannin stained sub‐drainages whereas those expressing the mosaic nuptial signal were more likely to be found in sub‐drainages that were not tannin stained. This result is consistent with the sensory drive model.
Growth rate responses of Missouri and Lower Yellowstone River fishes to a latitudinal gradient
Authors: Pegg M. A. , Pierce C. L.
Published: April 2005

Growth rate coefficients estimated for channel catfish Ictalurus punctatus, emerald shiners Notropis aherinoides, freshwater drums Aplodinotus grunniens, river carpsuckers Carpiodes arpio and saugers Stizostedion canadense collected in 1996–1998 from nine river sections of the Mssouri and lower Yellowstone rivers at two life‐stages (young‐of‐the‐year and age 1+ years)were significantly different among sections. However, they showed no river‐wide latitudinal trend except for age 1+ years emerald shiners that did show a weak negative relation between growth and both latitude and length of growing season. The results suggest growth rates of fishes along the Missouri River system are complex and could be of significance in the Management and conservation of fish communities in this altered system.
Physiological effects of saline waters on zander
Authors: Brown J. A. , Moore W. M. , Quabius E. S.
Published: April 2005

Rapid transfer of zander Stizostedion lucioperca to hypoosmotic brackish water (mean osmolality 230 mOsmol kg–1, c. 8 psu) significantly increased plasma chloride concentrations after 24 h compared to those transferred to fresh water, although plasma osmolality was not significantly affected. After 6 days, plasma osmolality was slightly elevated but stable plasma glucose and cortisol concentrations and blood haematocrit and haemoglobin suggest a lack of hormonal stress responses and resultant secondary effects. Rapid transfer of zander to a more saline environment, hyperosmotic to plasma (mean osmolality 462 mOsmol kg‐1, c. 16 psu) induced a greater increase in plasma osmolality and chloride concentrations within 24 h, with a further rise after 6 days exposure, but all fish maintained a state of hypo‐osmoregulation both 24 h and 6 days after transfer. The initial osmotic disturbance (at 24 h) was accompanied by increased plasma glucose, blood haematocrit and haemoglobin and a decreased mean cell haemoglobin concentration (MCHC), suggesting an adrenergic stress response, but these parameters fully recovered within 6 days of exposure to this hyperosmotic environment with MCHC rising to exceed the level in freshwater fish. Zander did not survive rapid transfer to more hyperosmotic conditions (750 or 1001 mOsmol kg‐1, 26‐35 psu), but they did survive exposure to simulated‘tidal cycles’ of rising and declining salinity, peaking after 6 h at c. 29 or 33 psu. Although osmotic disturbance was apparent after 6 h exposure and other physiological parameters suggested both adrenergic and corticosteroid components of a stress response, rapid recovery was apparent after return to fresh water. The results indicate that the zander, a non‐indigenous species in the U.K., has a high level of osmotic tolerance and a degree of hypo‐osmoregulation in saline environments not found in most stenohaline freshwater teleosts. This osmoregulatory ability could enable invasion of new U.K. river systems by using inshore marine environments of low salinity as saltwater bridges.
Within‐stream variation in early life‐history traits in brown trout
Authors: Olsen E. M. , Vøllestad L. A.
Published: April 2005

Significant additive genetic variance for most early life‐history traits was found in brown troutSalmo truttaliving in both allopatry above an impassable waterfall and sympatry (below the waterfall in the same stream) with alpine bullheadCottus poecilopus.These traits included length, mass and yolk sac volume at hatching, and size at‘button‐up’ (the time when yolk is enclosed within the body cavity). There were small differences in size at hatching and size at button‐up among populations (adjusted for egg size). However, sympatric fry grew more rapidly and experienced lower mortality rates during the period of first feeding than allopatric fry. This might indicate behavioural differences between brown trout from the two populations. It is suggested that these phenotypic differences may be a result of adaptation to living in sympatry with alpine bullhead.
Molecular identification (RAPD) of the eight species of the genus Barbus (Cyprinidae) in the Iberian Peninsula
Authors: Callejas C. , Ochando M. D.
Published: April 2005

Random amplified polymorphic DNA (RAPD) analysis has been used to identify the eight Barbus species of the Iberian Peninsula, whose morphological differentiation is difficult. Ten random primers were employed to generate RAPD markers. Different RAPD profiles were observed for the different species. Four species‐specific markers were found in B. bocagei, seven in B. comizo, five in B. graellsii, three in B. guiraonis, eight in B. haasi, 13 in B. meridionalis, four in B. microcephalus and four in B. sclateri. Evidence is presented that RAPD markers constitute useful tools for accurate taxonomic identification of Spanish barbels which is one of the first prerequisites in effective conservation programmes.
A grid‐net technique for the analysis of fish positions within free‐ranging shoals
Authors: Hoare D. J. , Ward A. J. W. , Couzin I. D. , Croft D. P. , Krause J.
Published: April 2005

The design and operation of a grid‐net are described, which allows the capture of entire shoals of wild fish and preserves information about the two‐dimensional structure of shoals and the spatial positions of individual fish within the shoal. This simple technique facilitates investigation of several aspects of individual differences in fish shoaling behaviour in the wild for the first time.
Changes in hypoxia tolerance during metamorphosis of bonefish leptocephali
Authors: Pfeiler E.
Published: April 2005

Survival times of metamorphosing leptocephali of the bonefish Albula sp. placed in hypoxic sea water (0·68 mg O2 l‐1) decreased by about three‐fold (from c. 15 to 5 min) over the 10 day metamorphic period. Increased sensitivity to hypoxia coincided with increased larval oxygen demand during metamorphosis. Plots of hypoxic survival time against standard length or wet mass suggested that metamorphosis (phase II of larval development) could be divided into subphases (IIa and IIb). American Public Health Association.
Strong piscivory of Japanese Spanish mackerel larvae from their first feeding
Authors: Shoji J. , Tanka M.
Published: April 2005

Dietary preference of Scomberomorus niphonius larvae for fish prey over invertebrate plankton prey were supported by rearing experiments. The larvae exhibited almost exclusive piscivory from their first feeding in tanks. The ratio of invertebrate plankton: fish prey was 1200: 1.
Phylogenetic relationships of bitterlings based on mitochondrial 12S ribosomal DNA sequences
Authors: Okazaki M. , Naruse K. , Shima A. , Arai R.
Published: April 2005

Analysis of the nucleotide sequence of the mitochondrial 12S ribosomal RNA gene of 27 species or sub‐species of bitterlings showed that bitterlings comprise an Acheilognathus clade and a Tanakia‐Rhodeus clade, partially supporting an earlier classification based on morphology and karyology. The monophyly of Acheilognathus is confirmed, but that of Tanakia and Rhodeus remains poorly resolved. Within the Tanakia–Rhodeus clade, all species or sub‐species having a diploid chromosome number of 46 form a monophyletic group. Results support the hypothesis that evolutionary trends of bitterling karyotypes involve reduction from 2n=48 to either 2n=44 (by Robertsonian translocation) or 2n=46 (by non‐Robertsonian translocation).
Discrimination of family‐specific odours by juvenile coho salmon: roles of learning and odour concentration*
Authors: Courtenay S. C. , Quinn T. P. , Dupuis H. M. C. , Groot C. , Larkin P. A.
Published: April 2005

Free‐swimming coho salmon fry Oncorhynchus kisutch of some families showed preference (relative to the behaviour of naïve sibs) for the odours of similarly aged non‐sibs to whom they had been exposed during the post‐hatch (alevin) stage and the early free‐swimming (fry) stage, but not the embryo (egg) stage, indicating that odour‐learning had occurred during the later developmental periods. Recognition (i.e. preference) of sib‐ pecific odours was evident after a month, and in one case 5 months, of separation from those odours. Thus, young salmon incubating in their gravel nests in streams appear to have the capacity to learn the chemical characteristics of conspecifics and retain this memory for at least several months without reinforcement. However, in addition to the general attractiveness of sibs and familiar non‐sibs over unfamiliar non‐sibs, some non‐sibs were consistently more attractive than others. Preference between two different non‐sib odours could be reversed by changing their relative concentrations, indicating that relative attractiveness is a function of both familiarity and odour concentration. Therefore, although juvenile coho salmon learn, remember, and are subsequently attracted by sib‐specific odours in early life, familiar odours are not always preferred over unfamiliar conspecific odours. Preference in dyadic assays is therefore an insensitive measure of recognition.
Analysis of stable isotope ratios to investigate stock structure of red emperor and Rankin cod in northern Western Australia
Authors: Stephenson P. C. , Edmons J. S. , Moran M.J. , Caputi N.
Published: April 2005

The ratios of stable isotopes 18O/16O and 13C/12C, in sagittal otolith carbonate from two tropical demersal teleosts, red emperor Lutjanus sebae and Rankin cod Epinephelis multinotatus, from several locations in northern Western Australia, differed between sites. On a broad scale, fish from the four locations, Shark Bay, Ningaloo, Pilbara, and Broome had stable isotope values that were sufficiently different to indicate separate stocks, and it is appropriate to manage these populations of the two species independently in these areas. On a smaller scale, there may be limited mixing of these species between the Pilbara trawl fishery and the trap and line fisheries operating out of Onslow and Broome. Values of stable oxygen isotopes were strongly related to sea surface temperature, although there were some sites in shallow water where low values of stable oxygen isotopes indicated that fish were living in warm water. The use of stable oxygen and carbon isotope values is a valuable, cost effective method of determining the degree of mixing of fish stocks.
The effect of feeding regime on growth, locomotor activity pattern and the development of food anticipatory activity in greenback flounder
Authors: Chen W‐M. , Purser G. J.
Published: April 2005

The mean final weight of juvenile greenback flounderRhombosolea tapirinafed a single daily meal during the scotophase was lower than that of groups fed continuously or fed twelve, six, three or one meal during the photophase. Final weight did not differ among the latter five groups. Size variation in all groups of fish decreased during the course of the trial over 120 days. Groups assigned to a higher frequency (and hence a longer total daily meal duration) of daily meals were less active during mealtime. A distinct food anticipatory effect was observed in the groups of fish receiving a single daily meal during either photophase or scotophase, and also developed before at least one meal in the group of fish fed three meals per day.
The effect of meal size and meal duration on food anticipatory activity in greenback flounder
Authors: Purser G. J. , Chen W‐M.
Published: April 2005

Latency of food anticipatory activity (FAA) in greenback flounder Rhombosolea tapirina was about 21 days. Fish fed at meal sizes of 0·25 and 0·5%W day−1 exhibited FAA under meal durations of 1, 3 and 7 h. Fish fed at 1·5%W day−1 showed FAA only at a meal duration of 1 h. At each meal size, FAA was shorter and lower the longer the duration of the meal. The mean durations of FAA and post‐feeding activity were correlated positively (r=0·87; P<0·01; n=7). FAA persisted for <3 days during food deprivation. It is suggested that greenback flounder was capable of evaluating the energetic and temporal impacts of a single daily meal.
Genetic differentiation of European grayling populations across the Main, Danube and Elbe drainages in Bavaria
Authors: Gross R. , Kühn R. , Baars M. , Schröder W. , Stein H. , Rottmann O.
Published: April 2005

Analysis of mitochondrial (ND‐1/3/4 genes) and nuclear (GH‐1 gene, four microsatellite loci) DNA markers of European grayling Thymallus thymallus populations identified strong genetic differentiation between the Rhine/Main, Elbe and Danube drainages in Bavaria, as a result of both present processes and past history. The Danube and the Main‐Elbe group diverged about five times earlier than the populations of Main and Elbe. These data suggest that exchange and transfer of grayling stocking material between these drainages should be avoided, to maintain the genetic diversity and integrity of populations.
The use of passive integrated transponder systems (PIT) triggered by infrared‐gates for behavioural studies in nocturnal, bottom‐dwelling fish species
Authors: Fischer P. , Kautz H. , Weber H. , Obergfell W.
Published: April 2005

The movements of juvenile burbot Lota lota were monitored continuously with an overall efficiency of 92·5%. The results show that passive integrated transponder (PIT) systems (or variations of them) are highly valuable for behavioural studies of small nocturnal fish species at the laboratory or mesocosm scale.
Polymorphism and speciation in Arctic charr
Authors: Jonsson B. , Jonsson N.
Published: April 2005

The Arctic charr Salvelinus alpinus exhibits 1–4 sympatric morphs in postglacial lakes, of which one or two are epibenthic zoobenthos feeders, one is a limnetic planktivore and one is a piscivorous form. In addition, northern rivers support partly migratory populations with anadromous and freshwater resident fish. The morphs vary in their coloration, morphology, life history, behaviour and genetic characteristics. The morphs usually differentiate according to their ontogenetic stage at maturity, which parallels paedomorphism in amphibians. The young usually start as epibenthic zoobenthivores, but may become pelagic at a certain size according to the predation risk experienced at that time. From a length of > 20–25 cm, charr start to become piscivorous. The proportion of piscivorous fish increases with increasing body size. In partly anadromous populations, fish that mature before smolting become freshwater resident, the others anadromous. In some rivers, the morphs occupy separate niches (epibenthic and limnetic), from emergence onwards. The morphs exhibit different degrees of reproductive isolation that vary from a high degree of interbreeding to complete isolation. Usually, they spawn within morph (assortative mating), but alternative male mating behaviour (sneaking, fighting) may occur in stream‐spawning populations and at great depths in lakes. Morphologically specialized morphs appear to feed more effectively than intermediate forms, and selection according to feeding mode, site fidelity and associated assortative mating are prerequisites for the evolution of the different morphs. Charr morphs develop into stable feeding niches under conditions of intense intraspecific competition when there is little competition with other species. Sympatric morphs exhibit different degrees of speciation, but similar morphs in different systems are not individual species because of (1) their polyphyletic origin, (2) the supporting systems are often young, transient environments making the future situation for the populations uncertain, and (3) the genetic differentiation among morphs is low. Sympatric morphs may interbreed and produce fertile hybrids. Nevertheless, sympatric charr morphs should be managed as separate species. Changes in the natural conditions or human impacts to which the morphs are adapted will have a strong influence on the persistence and survival of each different morph.
Pattern of gonad maturation and the question of semelparity in the paedomorphic goby Aphia minuta
Authors: Caputo V. , Candi G. , La Mesa M. , Arneri E.
Published: April 2005

At variance with previous reports, the paedomorphic goby Aphia minuta does not show semelparity, but abbreviate iteroparity like other small Mediterranean gobiid species. In spring, the mature ovary contains several batches of eggs at different stages of vitellogenesis. This indicates that the breeding season of A. minuta is quite long and that spawning takes place at least twice during its short lifespan, involving in each ovulatory wave different batches of oocytes which undergo vitellogenesis at different times. These observations agree with the testicular cycle data. In males, which in spring exhibit active spermiation coinciding with deposition of the first batch of oocytes, spermatogonial mitosis also resumes, eventually resulting in the production of new sperm in summer.
Development of bile salt‐dependent lipase in larval turbot
Authors: Hoehne‐Reitan K. , Kjørsvik E. , Gjellesvik D. R.
Published: April 2005

Pancreatic bile salt‐dependent lipase (BSDL) was present with 0·5 μg BSDL larva−1 from hatching in turbot larvae. The enzyme content increased during the yolk sac phase to 1·1 μg BSDL larva−1. This suggests that larval turbot are able to digest lipids from the start of exogenous feeding. The BSDL synthesis was stimulated first by food about 5 days after the onset of first feeding. The content per larva increased exponentially in fed larvae to 20 μg BSDL larva−1 on day 23 after hatching and decreased in starved larvae. In contrast, the specific content decreased during the first feeding phase, meaning that smaller larvae had a higher content of enzyme related to their biomass than did bigger larvae.
Amphibious behaviour and feeding ecology of the four‐eyed blenny (Dialommus fuscus, Labrisomidae) in the intertidal zone of the island of Santa Cruz (Galapagos, Ecuador)
Authors: Nieder J.
Published: April 2005

The labrisomid Dialommus fuscus, endemic to the Galapagos archipelago, is a predator of crustaceans, which moves up and down the intertidal zone with the tides. Its divided eye and elongated body permit it to forage in the wet sections of the intertidal habitat during low tide, both on the rocks and below the water line and in tide pools. Compared with other intertidal fishes (e.g. Bathygobius sp.), it was present on the rock flat in significantly smaller tide pools nearer to the water line during low tide.
Study of the sexual maturity of female bluefin tuna: purification and partial characterization of vitellogenin and its use in an enzyme‐linked immunosorbent assay
Authors: Susca V. , Corriero A. , Bridges C. R. , De Metrio G.
Published: April 2005

Plasma steroid levels of female bluefin tuna (BFT) Thunnus thynnus rose from c. 1·5 ng ml−1 during the quiescent period (March) to c. 7 ng ml−1 during the ripening period (May). Testosterone (T) increased further to c. 8 ng ml−1 during the pre‐spawning period (June) while 17β‐oestradiol (E2) began to decrease. In the post‐spawning period (August) steroid levels decreased to < 1 ng ml−1. Vitellogenin (Vtg) plasma levels seemed to follow changes in E2, showing an increase from the quiescent period to the ripening period of c. 18 mg ml−1, decreasing slightly before spawning, and then decreasing after spawning. The Vtg content in plasma showed a good correlation both with the plasma levels of E2 and T and with the percentage of vitellogenic oocytes at different periods of the reproductive cycle. Thus the ELISA could be taken as validated. Immunohistochemical staining of ovaries with anti BFT‐Vtg serum demonstrated a high cross‐reactivity with yolk proteins allowing the identification of vitellogenic oocytes.
Relationship between morphology and diets of six neotropical loricariids
Authors: Delariva R. L. , Agostinho A. A.
Published: April 2005

Most loricariids are algivorous and detritivorous and play an important role in both the grazer and detritus food chains of neotropical waters. Relationships between morphological variation and diet were analysed in six syntopic species (Rhinelepis aspera, Hypostomus regani, H. ternetzi, H. margaritifer, H. microstomus and Megalancistrus aculeatus) fished commercially in a 10 km2 area of the Upper Paraná River upstream from the Itaipu Reservoir. Species feeding on fine grained detritus use suction to obtain food, and possess a well‐developed respiratory membrane, long gill rakers, rudimentary labial and pharyngeal teeth, a thin stomach wall, and a long intestine. Species feeding on coarser material (e.g. periphyton), ingest food by scraping the substratum. Their morphological characteristics are large, strong, spatulate teeth, short gill rakers, a well‐developed stomach, and a shorter intestine. The first species group is composed by R. aspera while the latter by M. aculeatus and H. microstomus. The others species had an intermediary position.
Myxobolus dahomeyensis infection in ovaries of Tilapia species from Benin (West Africa)
Authors: Grankoto A. , Pampoulie C. , Marques A. , Sakiti G. N.
Published: April 2005

The prevalence of Myxobolus dahomeyensis in ovaries of Tilapia zillii was 31·6% and 18·3% in Sarotherodon melanotheron melanotheron. The parasite induced destruction of the oocytes and host castration. Its ovoid spore was 6·5–12·0 × 6·0–8·0 μm and the polar capsules averaged 3·6 × 2·2 μm (n= 30).
Androgen levels and social interactions in breeding males of the peacock blenny
Authors: Oliveira R. F. , Almada V. C. , Gonçalves E. J. , Forsgren E. , Canario† A. V. M.
Published: April 2005

Nest‐holder male Salaria pavo have lower circulating concentrations of 11‐ketotestosterone (KT) at the beginning of the breeding season than at its peak. At that peak density of nesting males was higher as were the number of visits of sneaker males to nests and of agonistic interactions between nest‐holders and sneaker males. There was no difference between the two dates either in the frequency of male‐male interactions or in the frequency of courtship episodes. Thus, higher plasma levels in nest‐holders might be explained by a more intense sneaking pressure at the peak of the breeding season. At that peak, nest‐holders had higher plasma levels of KT and a higher testosterone (T) to KT metabolization index in the gonads than did floater males. Both nest‐holders and floaters had higher levels of KT and T in the testicular gland than in the testis. The levels of both androgens in the testicular gland, but not in the testis, were correlated with circulating concentrations of KT. These results suggest that the testicular gland is the major source of circulating KT in blenniids. Nest‐holders had higher metabolization indexes than floaters both in the testis and in the testicular gland, which suggests that nest holding status promotes the conversion of T into KT.
Reproduction in the dusky grouper from the southern Mediterranean
Authors: Marino G. , Azzurro E. , Massari A. , Finoia M. G. , Mandich A.
Published: April 2005

Demographic data and gonad histology confirmed that the dusky grouper Epinephelus marginatus is a protogynous hermaphrodite that follows a monandric pathway to sexual development. Females reached first sexual maturity at 36·7 cm Ls and estimated mean length at first maturity (L50) was 43·8 cm Ls for females and 81·3 cm Ls for males. Adult sex ratios during the reproductive period were c. 3·5: 1 females to males. Females exhibited group‐synchronous ovarian development and multiple ovulation occurred over the spawning period. Gonads were ripe from early May and spawning occurred from June until early September. The size of ripe testes (0·6%W)indicated strong oligospermy and suggested a mating system with no sperm competition. Sexual transition was protogynous involving regression of ovarian tissue and proliferation of testicular tissue in the gonads. Transitional individuals occurred from May through November and accounted for 9% of sampled adult population. Sex change occurred in fish 69–93 cm (Ls) long and the size distributions of males and females overlapped over 27% of the Ls range. Special zones were recognized as gathering areas for sexually mature dusky groupers during the reproductive period.
Compensatory growth in the gibel carp following feed deprivation: temporal patterns in growth, nutrient deposition, feed intake and body composition
Authors: Xie S. , Zhu X. , Cui Y. , Wootton R. J. , Lei W. , Yang Y.
Published: April 2005

To investigate the nature of compenstory growth in fish, an 8 week study at 28°C was performed on juvenile gibel carpCarassius auratus gibelioweighing 6·6 g. Fish were starved for 0 (control), 1 (S1) or 2 (S2) weeks and then re‐fed to satiation for 5 weeks. Weekly changes in weight gain, feed intake and body composition were monitored during re‐feeding. No significant difference was found in final body weight between the three groups, indicating complete compensation in the deprived fish. The deprived groups caught up in body weight with that of the control after 2 weeks of re‐feeding. Body fat: lean body mass ratio was restored to the control level within 1 week of re‐feeding. In the re‐feeding period, weekly gains in body weight, protein, lipid, ash and energy in the S1 group were significantly higher than in the controls for 1 week. For the S2 group, weekly gains in body weight, lipid, ash and energy were higher than in the controls for 2 weeks, and gain in protein was higher than in the controls for 3 weeks, though gain in body energy became elevated again during the last 2 weeks of the experiment. Feed intake remained higher than the control level for 3 weeks in the S1 group and 4 weeks in the S2 group. Growth efficiency was not significantly different among the three groups in any of the weeks during re‐feeding. Compensatory responses in growth and especially feed intake tended to last longer than the recovery of body composition.
Lipid class dynamics during development in early life stages of shortbelly rockfish and their application to condition assessment
Authors: Norton E. C. , MacFarlane R. B. , Mohr M. S.
Published: April 2005

Lipid class dynamics and the relationship between weight and length were analysed during early life stage (ELS) development in wild populations of shortbelly rockfish Sebastes jordani to investigate their utility in a condition or nutritional status assessment. Analyses from more than 3000 field‐captured shortbelly rockfish indicated little variation in weight for a given length and provided limited application in the assessment of condition. The fractionation of total lipids into individual classes revealed trends in lipid metabolism throughout development. These trends were described best using a stage‐specific regression model, since Sebastes show defined early life history transitions. Among developmental stages, triacylglycerols (TAG) and polar lipids (PL) were the dominant lipid classes and cholesterol (CHOL), sterol/wax esters, and nonesterified fatty acids were found in lower concentrations. In the preflexion stage, low concentrations and constant levels of TAG along with the combined influence of endogenous and exogenous sources of energy compromised the use of TAG as an index of nutritional status. However, during flexion through juvenile stages, TAG levels increased indicating an accumulation of energy reserves with development, thus providing a valid indicator of nutritional status in later stages. Large fluctuations in PL concentrations during development suggested complex metabolism which may be due to changes in cell volume and cell membrane proliferation with development as well as catabolism. CHOL declined in larval stages, then remained constant with increasing size through the juvenile stage, negating its use as a normalizer for variations of mass in a TAG/CHOL ratio prior to juvenile transformation. This study provides the first documentation of lipid dynamics during early life stages following parturition in a marine viviparous teleost.
Morpho‐anatomy of the otic region in carapid fishes: eco‐morphological study of their otoliths
Authors: Parmentier E. , Vandewalle P. , Lagardère F.
Published: April 2005

Carapid species are characterized by so‐called otophysical structures (sonic muscles, broad first apophyses covering the anterior part of the swimbladder, etc.) The family includes pelagic (Pyramodon and Snyderidia) and benthic (Echiodon) species and ones that are either commensal with (Onuxodon, Carapus) or parasites of (Encheliophis) invertebrates (sea cucumbers, etc). The aim of the present work was to seek possible relationships between the structures of the inner ear (particularly the sagitta) on the one hand and otophysical structures and lifestyles within the Carapidae family. In the eight species studied, the otic cavity is wide, the saccular otosac and its sagitta are particularly developed. The sacculi touch each other on the median line. A comparison of the inner ear structures reveals notably that the species with the most developed sagitta and sacculus are those with the largest parapophyses and have a commensal or parasitic lifestyle.
Growth and physiological changes during metamorphosis of Senegal sole reared in the laboratory
Authors: Fernández‐Díaz C. , Yýfera M. , Cañavate J. P. , Moyano F. J. , Alarcón F. J. , Díaz M.
Published: April 2005

The metamorphosis of Solea senegalensis was studied in larvae reared at 20° C and fed four different feeding regimes. A, Artemia (4 nauplii ml−1); B, Artemia (2 nauplii ml−1); C, mixed diet (2 nauplii ml−1 and 3 mg ml−1 microencapsulated diet); and D, microencapsulated diet (3·7 mg ml−1). Rotifers were also supplied in all cases during the first days of feeding. These feeding regimes supported different growth rates during the pre‐metamorphosis period (regime A, G=0·376 day−1; regime B, G=0·253 day−1; regime C, G=0·254 day−1; regime D, G=0·162 day−1). Larvae started metamorphosis 9 days after hatching (DAH) when fed the regime A, 13 DAH with regime B, 11 DAH with regime C and 15 DAH with regime D. A minimum 5·6–5·9 mm LT was required under all feeding regimes to initiate the metamorphosis. Eye translocation was completed when the larvae reached 8·6–8·7 mm LT (regimes A, B and C), but only 7·3 mm LT with regime D. 4·4–6·2 days were required to complete eye migration under the regimes A, B and C, and 18·3 days under the regime D. This transformation is concomitant with changes in body reserves, and with the pattern of some digestive enzymes.