bluuebunny/crossref_metadata_2025 huggingface dataset:
Histochemical differentiation of glycoconjugates occurring in the tilapine intestine
Authors: Scocco P. , Menghi G. , Ceccarelli P.
Published: April 2005

The glycoconjugates secreted by the anterior and posterior intestinal segments of Tilapia spp. were characterized by means of both conventional histochemical procedures (PAS, AB, AB‐PAS, LID, HID) and a battery of 12 horseradish peroxidase labelled lectins. Some sections were treated with glycolytic enzymes and KOH before conventional and lectin stainings. The large majority of the mucopolysaccharides secreted by the goblet cells of the anterior segment are carboxylated while only a few carry sulphate groups. The mucopolysaccharides in the anterior intestine contained chondroitin, heparin and chondroitinsulphates which can provide protection for intestinal mucosae. DBA lectin staining demonstrated the presence of some endocrine cells in the anterior segment.
Fish communities along an oxygen‐poor salinity gradient (Zeeschelde Estuary, Belgium)
Authors: Maes J. , van Damme P. A. , Taillieu A. , Ollevier F.
Published: April 2005

Fish living in the tidal fresh and brackish water reaches of the Zeeschelde Estuary were studied in samples collected from the cooling‐water inlets of three power stations. Between July 1994 and June 1995, 42 different species were recorded including 26 marine migrants, 14 freshwater species and two diadromous species. Species number as well as fish abundance were correlated significantly with salinity and oxygen concentration. The community structure was analysed with a correlation biplot based on principal component analysis of the root‐root transformed fish abundance. Four separated communities could be distinguished since the first principal component expressed a salinity and the second a temperature gradient. During summer and fall Pomatoschistus microps, P. minutus, P. lozanoi and Syngnathus rostellatus were most abundant in the brackish‐water reach. At this time, freshwater species seemed to avoid the freshwater area. During winter, Sprattus sprattus, Clupea harengus and Dicentrarchus labrax were the dominant species of the brackish‐water zone while the freshwater reaches were dominated by Gasterosteus aculeatus . Migrating fish such as Pleuronectes flesus, Lampetra fluviatilis, Anguilla anguilla and Osmerus eperlanus were restricted to the brackish environment.
Carbon dioxide anaesthesia in rainbow trout: effects of hypercapnic level and stress on induction and recovery from anaesthetic treatment
Authors: Bernier N. J. , Randall D. J.
Published: April 2005

The physiological and anaesthetic effects of three different levels of air‐saturated and buffered CO2 anaesthesia, Pwco2=31, 78, or 125 mmHg, were examined in cannulated rainbow trout Oncorhynchus mykiss . Complete anaesthesia (no opercular movements) was not achieved by these hypercapnic levels after 20 min of CO2 exposure. Although increasing Pwco2 reduced the induction times to the early stages of anaesthesia, it also resulted in increasing hyperventilatory, hypoxaemic, and acid‐base disturbances. After a 10‐min recovery period, while the respiratory acidosis component of the acid‐base disturbance was corrected, there was a significant metabolic acidosis. Recovery time was longest in the high Pw co2 treatment where 33% of the fish died. Two additional groups (Pwco2=37 and 78 mmHg) were exposed to an acute stress prior to the anaesthetic treatment. Stress reduced the hypoventilatory effects of the low Pwco2 treatment, increased the recruitment of anaerobic metabolism, and prolonged recovery time. Although the increase in plasma catecholamines elicited by the stress was small relative to the response obtained with the anaesthetic, stress prior to CO2 anaesthesia impaired the efficiency of the treatment. Overall, our results suggest that Pwco2 levels above 37 mmHg and/or stress prior to the anaesthesia impair the efficiency of air‐saturated and buffered CO2 anaesthesia by exacerbating the hypoxaemic effects of the hypercapnic treatment.
The growth of whitefish in relation to water quality and fish species composition
Authors: Raitaniemi J. , Malinen T. , Nyberg K. , Rask M.
Published: April 2005

Water quality in 16 Finnish lakes did not affect directly densely gill‐rakered whitefish growth, except possibly in an acid (pH 4·9) lake, Iso Lehmaälampi, where acidity may have retarded the growth of whitefish. The density of roach affected whitefish growth in the second year of life: highest growth rates were in lakes without a roach population and lowest growth rates in lakes having strong roach populations. Competition by vendace also retarded the growth of young whitefish. The efficient mass removal of roach from a eutrophic lake was considered to have increased the growth rate of young whitefish. It is suggested that an examination of the fish species composition and relative abundance, as well as the growth of whitefish, can be used as an aid in predicting the success of stocking with whitefish.
Poststress levels of lysozyme and cortisol in adult rainbow trout: heritabilities and genetic correlations
Authors: Fevolden S.‐E. , Røed K. H. , Fjalestad K. T. , Stien J.
Published: April 2005

Lysozyme response in stressed rainbow trout was compared with measurements of poststress cortisol activity. Estimates of heritability of lysozyme and cortisol were both moderate‐to‐high and both traits displayed positive genetic correlations in pair‐wise comparisons of stress exposures. Genetic correlations between lysozyme and cortisol in stressed rainbow trout tended to be negative, although insignificant. Neither lysozyme, nor cortisol exhibited significant correlations with serum haemolytic activity. It is concluded that the data do not confirm earlier suggestions that lysozyme should be superior to cortisol in consistency of stress response in rainbow trout.
Blood flow distribution and tissue allometry in channel catfish
Authors: Schultz I. R. , Barron M. G. , Newman M. C. , Vick A. M.
Published: April 2005

Blood flow (as percentage of cardiac output) in fasted channel catfish acclimated to 21°C was directed primarily to white muscle (72%) followed by head kidney (5·7%), red muscle (5·5%), trunk kidney (3·1%), liver (2·2%), swim bladder (1·4%) and skin (1·1%). The stomach, intestines, pyloric caeca, gonads, brain, abdominal fat and spleen contained <0·5% of blood flow. There was considerable interfish variation among blood flow distribution to visceral organs with substantial spatial heterogeneity of blood flow to white muscle. The spatial heterogeneity of flow to muscle prevented accurate estimation of total flow to this tissue based on the microsphere deposition of a few sub‐samples. Instead, a novel approach, based on the whole animal counting of the eviscerated carcass was used to measure blood flow to white muscle. The scaling relationships for tissue mass in catfish (63–1873 g) followed the allometric equation (aWb) and tended to exhibit negative allometry, with organ weight decreasing in proportion to body weight. The b values for most tissues ranged between 0·83 and 1·0. The relative mass of the brain showed the greatest decline and with a b value of 0·32. The results, together with previous data on cardiac output, permitted calculation of organ blood flow rates in channel catfish. © 1999 The Fisheries Society of the British Isles
Lipid class composition of the viviparous yellowtail rockfish over a reproductive cycle
Authors: Norton E. C. , MacFarlane R. B.
Published: April 2005

Triacylglycerols (TAG) were the dominant lipids in liver tissue of both sexes of the viviparous yellowtail rockfish Sebastes flavidus during the spring and summer when greatest feeding occurred. Significant declines in liver TAG during the winter corresponded to increased concentrations of polar lipids (PL), the main component of cell membranes. Elevated PL in female livers relative to those of males preceded the period of ovarian enlargement and may be attributed to the production of vitellogenin. During late vitellogenesis and gestation, ovaries contained significantly elevated concentrations of PL, TAG, and cholesterol. Since yellowtail rockfish are highly fecund and viviparous, large quantities of ovarian PL are required for proliferation of the cell membranes in developing larval tissues. TAG accumulated in ovaries in lower concentrations than PL and were likely metabolized as the main source of energy during gestation. This pattern of ovarian PL concentrations exceeding those of TAG and the presence of oil globules, may be unique to highly fecund, viviparous teleosts and signify an alternative profile to those previously documented for oviparous species. Testes at maximum IG were only 7% of maximum ovarian size, composed of mainly PL, and lacked a defined lipid dynamic pattern across the reproductive cycle.
Foraging interactions among three benthic fish in a Posidonia oceanica reef lagoon along the Tyrrhenian Coast
Authors: Pirrott M. De , Marchetti G. M. , Chelazzi G.
Published: April 2005

Three benthic predators Coris julis, Symphodus cinereus and Mullus surmuletus in a Posidonia oceanica reef lagoon of the Tyrrhenian coast had a broad diet, including hard‐bodied invertebrates such as crustaceans and molluscs, but revealed consistent interspecific differences. Diet overlap was greater between C. julis and M. surmuletus in comparison to other combinations. All three species were diurnal feeders, but with diVerent daily patterns of foraging based on diVerent prey availability. There was a general spatio‐temporal correlation in non‐foraging activity among the three species, but foraging activity was correlated only between C. julis and the other two species, but not between S. cinereus and M. surmuletus .There was heterospecific aggregation during foraging between C. julis and M. surmuletus, and possibly a scrounger–producer relationship between them. Fights between C. julis specimens related to foraging activity were common, but not between species. These results support the view that diVerences in spatio‐temporal organization of activity, and interactions during foraging, can contribute to resource partitioning among syntopic populations of fish belonging to the same trophic group.
Effects of natural and commercial diets on the fatty acid content of European grayling
Authors: Ahlgren G. , Carlstein M. , Gustafsson I.‐B.
Published: April 2005

Eicosaenoic acid (20:1ω9) and docosaenoic acid (22:1ω11) levels were about 10 and 100 times higher in food pellets fed to cultured grayling than in the insect larvae on which wild grayling fed. Among the PUFA, docosahexaenoic acid (DHA) was very high in the pellets, resulting in an unnaturally elevated, and probably unbalanced, ω3/ω6 ratio of 7–13 in the cultured fish whereas the same ratio varied only from 4 to 6 in the wild fish. Despite very low DHA levels in the native food, wild grayling muscle tissue contained relatively high amounts of DHA. DHA is probably not essential in the diet of grayling.
New insights into the migration and habitat use by bream and white bream in the floodplain of the River Rhine
Authors: Molls F.
Published: April 2005

Bream Abramis brama, white bream Blicca bjoerkna and roach Rutilus rutilus all undertook spawning migrations from the River Rhine into oxbows. Adult white bream and roach returned to the river after spawning. This indicates an annual change of habitat allowing the use of optimal conditions in oxbows for spawning and growth of juvenile fish, and the use of feeding grounds rich in benthos in the main river by the adults. In contrast, adult bream were still present in large numbers in the oxbows over the summer. Juvenile bream (0+ and 1+) migrated to the main river. Bream aged 2+ to 4+ were not found in the oxbows, whereas they occurred frequently in the river. Thus bream show ontogenetic changes in their use of the main river and oxbows. The young fish spend their long juvenile phase in the river after leaving the oxbows. Reproduction in oxbows is ensured by mature fish migrating in for a short period from the river as well as by other adults (≥5+) that live permanently in the oxbows. The strong tendency of adult bream to develop permanent stocks in the oxbows gives this species a reproductive advantage, since many oxbows are accessible to Rhine fish only occasionally in the present hydrological situation.
Immunohistochemical identification of a vacuolar proton pump (V‐ATPase) in bone‐resorbing cells of an advanced teleost species, Oreochromis niloticus
Authors: Witten P. E. , Holliday L. S. , Delling G. , Hall B. K.
Published: April 2005

Poly‐and monoclonal antibodies, raised against mammalian membrane‐bound proton pump (V‐ATPase) were applied to the bone‐resorbing cells of Oreochromis niloticus to clarify if osteoclasts of an advanced teleost species display V‐ATPase, a key enzyme in the process of bone resorption. All antibodies labelled cells at known sites of bone resorption, the endosteal bone surfaces surrounding the tooth anlagen. The best results were achieved with a monoclonal antibody (E11). Although the majority of labelled cells were flat and mononucleated, the occurrence of V‐ATPase in these cells indicates that they function as active bone‐resorbing cells. The monoclonal antibody E11 was also applied successfully to monocytes, cells that are believed to be related most closely to osteoclasts. The assignment of V‐ATPase to boneresorbing cells of O. niloticus was confirmed by application of the additional osteoclast markers, tartrate‐resistant acid phosphatase (TRAP) and tartrate‐resistant ATPase (TraATPase). Co‐expression of V‐ATPase, TRAP and TraATPase in fish osteoclasts is demonstrated for the first time.
The combined effect of feeding time and ration on growth performance and nitrogen metabolism of greenback flounder
Authors: Verbeeten B. E. , Carter C. G. , Purser G. J.
Published: April 2005

Greenback flounder Rhombosolea tapirina (c. 2 g) fed to satiation had significantly (P <0·01) higher feed consumption in the evening than in the morning whereas there was no difference between feeding times for flounder fed restricted rations (1 or 2% body weight per day) because they consumed all of the ration. Differences in growth performance were due to feeding time and ration. Carcass moisture, lipid and energy content were significantly (P <0·001) different between rations; length gain was significantly affected by feeding time (P <0·05) and ration (P <0·001); weight gain showed a significant (P <0·001) interaction between feeding time and ration. The relationship between feed consumption and specific growth rate showed that the exponential gradient was significantly higher (P<0·01) for the evening fed fish and indicated feed efficiency for evening fed fish increased as feed consumption increased. Urea excretion increased from 12–20 to 58–63% of total nitrogen excretion at the 1 and 3% rations, respectively. Ammonia and urea excretion were significantly affected by ration (P <0·001) and feeding time (P <0·05). Fish fed the 2% ration in the evening had higher growth efficiency and significantly (P <0·01) lower rates of urea excretion than fish fed 2 or 3% ration in the morning. It is suggested that the higher energetic costs associated with differences in ammonia and urea excretion contributed to differences in growth efficiency.
Effects of osmolality and ions on the motility of stripped and testicular sperm of freshwater‐and seawater‐acclimated tilapia,Oreochromis mossambicus
Authors: Linhart O. , Walford J. , Sivaloganathan B. , Lam T. J.
Published: April 2005

A significantly higher concentration of testicular spermatozoa was obtained from freshwaterOreochromis mossambicus(9·9×109spermatozoa ml−1) than seawaterO. mossambicus(4·6×109spermatozoa ml−1). The mean osmolality of the urine of freshwater fish (78·5 mOsmol kg−1) was significantly different from that of seawater fish (304·8 mOsmol kg−1). The mean length of the mid‐piece of the spermatozoa together with the tail was more variable in freshwaterO. mossambicus(8·80±0·23μm) than in seawater specimens (8·27±0·18 μm). Stripped sperm of freshwaterO. mossambicuswas highly contaminated by urine which was a good activator of sperm motility inO. mossambicusheld in both fresh and sea water. The osmolality for initiation of motility in freshwaterO. mossambicusspermatozoa was from 0 to 333 mOsmol kg−1while for seawaterO. mossambicusspermatozoa it was from 0 to 1022 mOsmol kg−1. The optimum osmolality for motility was from 70 to 333 mOsmol kg−1for freshwaterO. mossambicusspermatozoa and from 333 to 645 mOsmol kg−1for seawater fish. In freshwaterO. mossambicusspermatozoa, the presence of 20 mM CaCl2increased the permissive osmolality of NaCl from 184 to 645 mOsmol kg−1. For seawaterO. mossambicusspermatozoa, solutions of NaCl devoid of CaCl2were unable initiate motility, but the addition of 1·5 to 30 mM CaCl2to the NaCl solution (0–934 mOsmol kg1) had a full motility initiating effect.
Endurance of simulated winter conditions by age‐0 walleye pollock: effects of body size, water temperature and energy stores
Authors: Sogard S. M. , Olla B. L.
Published: April 2005

Survival of age‐0 walleye pollock Theragra chalcogramma in the absence of food followed simple bioenergetic models, with large body size, high initial condition, and cold temperatures all increasing survival rates. High survival after >200 days at cold temperatures (<3·0° C) indicated extended tolerance of extreme cold, as long as sufficient body size and condition are attained during the summer growth period. Analysis of body constituents demonstrated a substantial increase in tissue water and depletion of lipid during starvation. Survivors had significantly higher lipid stores than mortalities, and larger fish had higher levels of lipid than smaller fish among experimental survivors, laboratory fish that were never starved, and wild fish. Fish returned to warm temperatures and high rations following 205 days of food deprivation displayed nearly complete recovery, with rapid increases in length, weight, and condition and minimal mortality (6·8%) during the subsequent 3 months. Age‐0 walleye pollock collected in September in the Bering Sea were substantially smaller and generally had lower lipid levels than fish used in laboratory starvation experiments, suggesting they are susceptible to size‐ and condition‐dependent mortality during the winter. The results are interpreted with respect to field distributions of age‐0 walleye pollock, overwinter survival, and synergistic effects of food and temperature under varying models of climate change.
The effects of thermal effluent exposure on the gametogenesis of female fish
Authors: Lukšienė D. , Sandström O. , Lounasheimo L. , Andersson J.
Published: April 2005

High temperature in Swedish and Lithuanian thermal effluent areas influenced gametogenesis of female perch Perca fluviatilis, roach Rutilus rutilus and pike Esox lucius negatively, indicating reduced reproductive capacity. Oocyte atresia started during vitellogenesis in autumn, and was often followed by asynchronous egg cell development. Among other anomalies, multi‐nucleus oocytes and hermaphroditism were observed. No significant impact was seen in silver bream Blicca bjoerkna. Ruffe Gymnocephalus cernuus reacted by a tendency to produce an additional mature oocyte generation during the spawning period. Ovaries in roach from coastal areas were often infected by a microsporidian parasite Pleistophora mirandellae, causing severe damage to the gonad. Parasites were also detected in pike, but neither in perch nor in lake populations of roach. Fish living in open coastal environments did not avoid impact by moving out of the heated areas. There seems to be a conflict in some temperate fish between temperature preference behaviour and safeguarding normal reproduction.
Seasonal changes in the diets and relative abundances of perch and roach in the littoral and pelagic zones of a large lake
Authors: Horppila J. , Ruuhijärvi J. , Rask M. , Karppinen C. , Nyberg K. , Olin M.
Published: April 2005

In the Enonselkä and Laitialanselkä basins of Lake Vesijärvi, perch Perca fluviatilis and roach Rutilus rutilus were abundant in the littoral and in the pelagic zones throughout the summer. In the littoral zone, roach was always more numerous than perch, while perch dominated in the open water. Intraspecific diet overlap values were higher than interspecific values. In the pelagic zone, perch <155 mm fed mainly on the cladoceran Leptodora kindtii, while small bosminids were most important food items for roach. Large perch were piscivorous, feeding mainly on smelt Osmerus eperlanus. In the littoral zone small perch foraged on zooplankton and chironomid larvae and large perch on chironomids and fish (small perch). Small roach fed mainly on bosminids and detritus, while for roach <185 mm macrophytes (Elodea Canadensis, Lemna trisulca) were also of importance. Detritus was more common in the food of roach in Laitialanselkä than in Enonselkä. The slower growth rate of roach in Laitialanselkä compared with Enonselkä was probably connected with this. However, considering the latitude of the lake, the growth rate of both roach and perch was relatively fast in both basins. The results indicated that in a large lake both perch and roach are able to utilize effectively the different habitats and diverse food resources. By segregation in food resource utilization they are able to co‐exist in large quantities, at the same time maintaining a relatively fast growth rate.
Temporal changes in enzyme activity and mRNA levels during thermal challenge in white sucker
Authors: Hardewig I. , Van Dijk P. L. M. , Leary S. C. , Moyes C. D.
Published: April 2005

In the early phases of warm acclimation in white sucker Castotomus commersoni, white muscle lactate and succinate, two endproducts of anaerobic energy metabolism, remained unchanged, indicating that energetic imbalance is not a prerequisite for alterations in enzyme levels. The changes in enzyme activities did not correlate with changes in mRNA levels, which argues against transcriptional regulation of enzyme expression under these conditions. The observed induction of cytosolic heat shock protein 70 suggests that the early phases of acclimation to strongly increased temperatures are dominated by enhanced protein degradation, leading to a new balance between synthesis and degradation and, therefore, new steady‐state enzyme concentrations.
Expressed sequence tags derived from brain tissue of Oreochromis niloticus
Authors: Hamilton L. C. , Macpherson G. R. , Wright J. M.
Published: April 2005

Expressed sequence tags (ESTs) were obtained from complementary DNA libraries derived from the brain of the cichlid fish, Oreochromis niloticus. Single‐pass sequencing of 183 cDNA clones generated 294 ESTs; 57 of these clones (31%) were identified based on their similarity to sequences in GenBank.
The influence of feeding regime on sexual maturation, fecundity and atresia in first‐time spawning turbot
Authors: Bromley P. J. , Ravier C. , Witthames P. R.
Published: April 2005

Exposure of adolescent turbot Scophthalmus maximus to low rations during vitellogenesis, covering the 4 months immediately prior to spawning, led to a drop of 70% in mean ovary weight, and was associated with poor growth of the vitellogenic oocytes or, in a third of cases, the absence of vitellogenic oocytes. Exposure to low rations during the recruitment of vitellogenic oocytes, 4–8 months prior to spawning, produced a more variable response. A few of these females produced well‐developed vitellogenic oocytes, but in most, vitellogenic oocytes were absent or only poorly developed and in some cases there was a high incidence of atresia. Exposure to intermediate rations throughout oocyte recritment and vitellogenesis also depressed oocyte development. In maturing females the number of non‐atretic vitellogenic oocytes (relative potential fecundity) averaged 998 per g of somatic body weight of fish at the start of the spawning season in mid‐June. Maturation of the males was not significantly influenced by the dietary regime. The small size of the testes and the low levels of milt production, even in fish fed high rations immediately prior to spawning, showed that reproductive investment in males was much lower than in females.
Effects of fish size on spawning time in Norwegian spring‐spawning herring
Authors: Slotte A. , Johannessen A. , Kjesbu O. S.
Published: April 2005

During October‐January in a northern Norwegian fjord system and in February‐March at the main western Norway spawning grounds, an index IG of gonad weight of spring‐spawning herring Clupea harengus in percentage of expected gonad weight at full maturity for a given total length LT, tended to increase with LT in the range 27–31 cm as the proportion of recruit spawners decreased. Insignificant differences in IG were found between LT groups in the range 32–37 cm (repeat spawners). This is contrary to that suggested in other studies and signifies that generally the stock spawns in only two waves, repeat spawners first and the recruit spawners second. IG also increased with somatic and total condition factor, which signifies that spawning time may be influenced by summer feeding conditions.
Variation in routine metabolism of juvenile muskellunge: evidence for seasonal metabolic compensation in fishes
Authors: Chipps S. R. , Clapp D. F. , Wahl D. H.
Published: April 2005

Metabolic rate of age 0 muskellunge Esox masquinongy ranged from 0·10 at 5° C to 0·24 mg O2 g‐1 h‐1 at 25° C and was significantly higher in spring and autumn than during winter months at comparable water temperatures. Reduced metabolic rate in winter was consistent with the metabolic compensation hypothesis, implying that metabolism of muskellunge varies independently of acclimation temperature and gonadogenesis. Moreover, seasonal variation in metabolic rate has important implications for energy budget studies. Single‐season estimates of esocid metabolism may be inadequate to describe annual energy requirements; the magnitude of errors will depend on the time of year metabolic rate was measured. As a result, it is suggested that seasonal variation in metabolic rate be incorporated into energy budget determinations for fishes.
Variations in juvenile growth, energy allocation and life‐history strategies of two populations of Arctic charr in North Norway
Authors: Rikardsen A. H. , Elliott J. M.
Published: April 2005

Within the populations of Arctic charrSalvelinus alpinusin Storvatn and Rungavatn, Norway, fish that attained the largest size in the late parr stage migrated as 4+ smolts, fish that attained a medium size became 5+ smolts, and the smallest parr became lake residents. Within the last 2 years of the parr stage, those that became anadromous had a lower growth rate during the winter and early summer than those that became resident, and vice versa in late summer. Thus, anadromous fish grew faster in the parr stage, but in years prior to migration, their growth pattern seemed to differ from that of parr that became resident. Due to early size differences between parr that became anadromous or resident, it is suggested that some of the basis for the decision to smoltify or not in charr depends on the growth rate through the whole parr stage, but with significant modification by the local environment. Rungavatn parr had a significantly higher population density (5 ×), higher lipid content and mortality, an earlier maturation, a lower rate of growth, and only one‐third the degree of anadromy than those from Storvatn. It is suggested that the two charr populations have evolved different life‐history adaptations due to unequal growth, energy allocation and competition opportunities in the lakes.
Chromosomal location of the 28S ribosomal RNA gene of channel catfish by in situ polymerase chain reaction
Authors: Zhang Q. , Cooper R. K. , Tiersch T. R.
Published: April 2005

This study describes the use of the polymerase chain reaction for physical mapping of fish genes. A 287–base pair (bp) fragment of the 28S ribosomal RNA gene (28S rDNA) of channel catfish Ictalurus punctatus was isolated and sequenced with human‐derived primers. The nucleotide (nt) sequence of this fragment was 20 bp shorter than that of the corresponding region of the human 28S rDNA. The gene was mapped to chromosomes of channel catfish by fluorescence in situ hybridization (FISH) and in situ polymerase chain reaction (ISPCR). A major locus and a minor locus of 28S rDNA were found on chromosomes of channel catfish. The major locus was associated with the active nucleolus organizer region (NOR) sites. The minor locus was highly resolved and not detectable by silver staining, suggesting that this locus was not involved in synthesis of ribosomal RNA and possessed fewer copies of 28S rDNA. Both loci contained GC‐rich DNA elements that could be components of 28S rDNA repeated units. In this study, a potential method of comparative mapping of the channel catfish genome has been presented by using human‐derived oligonucleotide sequences. These data demonstrate that ISPCR is highly specific and will be useful in physical mapping of fish genomes.
Bay‐scale population structure in coastal Atlantic cod in Labrador and Newfoundland, Canada
Authors: Ruzzante D. E. , Wroblewski J. S. , Taggart C. T. , Smedbol R. K. , Cook D. , Goddaard S. V.
Published: April 2005

Polymorphisms at five microsatellite DNA loci provide evidence that Atlantic cod Gadus morhua inhabiting Gilbert Bay, Labrador are genetically distinguishable from offshore cod on the north‐east Newfoundland shelf and from inshore cod in Trinity Bay, Newfoundland. Antifreeze activity in the blood suggests that Gilbert Bay cod overwinter within the Bay. Gilbert Bay cod are also smaller (weight and length) for their age and consequently less fecund for their age, than cod elsewhere within the northern cod complex. The productivity and recruitment potential of coastal cod off Labrador may thus be much lower than that of offshore northern cod or of inshore cod farther south, implying that a more conservative management strategy may be required for cod from coastal Labrador than traditionally practised for northern cod inhabiting less harsh environments. Relatively high FST and RST measures of population structure suggest that important barriers to gene flow exist among five components that include two inshore (Gilbert and Trinity Bay) and three offshore cod aggregations on the north‐east Newfoundland Shelf and the Grand Bank. DA and DSW estimates of genetic distance that involve Gilbert Bay cod are approximately three‐ and 10–fold larger, respectively, than estimates not involving Gilbert Bay cod. The differences between inshore cod from Gilbert Bay and Trinity Bay raise the possibility that other genetically distinguishable coastal populations may exist, or may have existed prior to the northern cod fishery collapse. Harvesting strategies for northern cod should recognize the existence of genetic diversity between inshore and offshore components as well as among coastal components.
Pigmentation development in hatchery‐reared flatfishes
Authors: Bolker J. A. , Hill C. R.
Published: April 2005

Malpigmentation is common in hatchery‐reared flatfishes, decreasing the market value of whole fish, and increasing the risk of predation for juveniles released to enhance wild stocks. Pigmentation development in flatfishes occurs in two phases. First, during embryonic and larval stages pigment cells differentiate on both sides of the body. Second, at metamorphosis larval melanophores disappear, and adult melanophores differentiate on the ocular but not on the blind side. Malpigmentation seems to result from disruptions of the second phase, and may take the form of albinism on the ocular side or darkening of the blind side. Both types of aberration may be related to aspects of the hatchery environment such as lighting, substratum, and diet. Larval nutrition appears to be a key factor and enrichment of larval diets with fatty acids and Vitamin A can greatly reduce malpigmentation rates; however, levels suffcient to prevent pigmentation defects frequently cause other abnormalities. Two developmental explanations for albinism have been proposed. The first is that differentiation of ocular‐side skin follows the normal blind‐side pathway and adult melanophores therefore fail to develop on the ocular side. The second hypothesis suggests that dietary deficiencies inhibit retinal development and the resulting visual defects lead to failure of a hormonal signal required for melanophore differentiation. These hypotheses may well be complementary; as yet neither has been thoroughly tested. Definitive tests will require a combination of manipulative techniques such as tissue transplantation and cell culture with nutritional, behavioural and hormonal assays. Such integrative studies will further the understanding both of normal pigmentation development and of the environmental factors that contribute to high rates of albinism in hatchery‐reared flatfish.
Lack of uptake of Renibacterium salmoninarum by gill epithelia of rainbow trout
Authors: Mcintosh D. , Austin B. , Fla E. , Villena A. , Matinez‐Pereda J. A. , Tarazona J.
Published: April 2005

The role of rainbow trout (Oncorhynchus mykiss, Walbaum) gill cells in uptake of the salmonid pathogen Renibacterium salmoninarum was examined using in vitro, whole animal and isolated perfused head models. Uptake of the pathogen was observed only when dissected gill tissue was exposed to the live pathogen. In contrast, live cells of Yersinia ruckeri interacted with the gill epithelia in the isolated perfused head model, confirming the findings of previous studies with whole animal and in vitro systems. These results are discussed in relation to the role of gill tissue in bacterial kidney disease (BKD) pathogenesis and in antigen trapping.
The southwestern Atlantic reef fish fauna: composition and zoogeographic patterns
Authors: Floeter S. R. , Gasparini J. L.
Published: April 2005

The Brazilian coast, the Caribbean and the tropical South Atlantic oceanic islands reef ichthyofauna separated into two major clusters: (1) the western Atlantic continental margin and Bermuda, further divided into (1a) the western North Atlantic, and (1b) the Brazilian coast; and (2) the South Atlantic oceanic islands, also divided in (2a) the Brazilian offshore islands, and (2b) Ascension and St Helena. Species geographic ranges suggest the recognition of only two western Atlantic zoogeographic provinces for tropical marine shore fishes. A Brazilian Province, including the offshore localities of Atol das Rocas, Fernando de Noronha, Trindade and St Paul's Rocks, and an expanded West Indian Province that includes Bermuda. Ascension and St Helena should be regarded as a separated Central Atlantic Province.
Skeletal characterization of wild and reared zebrafish: anomalies and meristic characters
Authors: Ferreri F. , Nicolais C. , Boglione C. , Bmertoline B.
Published: April 2005

Among two groups of wild and reared zebrafishes (zf) Danio rerio, all meristic characters considered were variable except the numbers of rays and pterygophores of the dorsal fin and the principal caudal fin rays, which tended to be canalized. Wild and reared individuals differed in the number of intervertebrae and anal pterygophores, and the dorsal and anal fin insertion. There were some skeletal anomalies of vertebrae and fins, particularly the caudal fin. Cephalic and Weber‐apparatus anomalies were rare. Types and frequencies of anomalies were quite similar in the two zf groups, but differences emerged for several less frequent anomalies. Such differences and the phenotypic variability of D. rerio make this species a perfect teleost model for investigating the influence of experimental or unfavourable environmental conditions on skeletal development of both domesticated and wild fish.
Mitochondrial cytochrome b sequence variation in Korean salmonids
Authors: Park J. Y. , Lee H. J. , Kim W. J. , Lee J. H. , Min K. S.
Published: April 2005

The complete 1141 bp mitochondrial cytochrome b sequences were determined for lenok Brachymystax lenok, cherry salmon Oncorhynchus masou masou, Ishikawa's cherry salmon O. m. ishikawai, chum salmon O. keta, rainbow trout O. mykiss, and an albino mutant of rainbow trout. Common substitutions detected in these species were transitional mutations. There were no significant differences in the intraspecific variation of the cytochrome b genes. Interspecific divergences were greater than intraspecific variation. The level of variation ranged from 8·026–15·686%. The cherry salmon was closer to chum salmon than to rainbow trout, and the lenok was the most distantly related species.
The relative in vitro responsiveness of melanophores of winter flounder to α‐MSH and MCH
Authors: Burton D. , Vokey J. E.
Published: April 2005

Melanin‐concentrating hormone (MCH) was more potent than the antagonistic melanophore stimulating hormone (α‐MSH) for the winter flounder Pleuronectes americanus when mixtures of the two were tested on melanophore preparations. Melanophores from individual pattern components displayed different relative sensitivities to the two hormones. These differences indicate that there are pattern‐related variations in MCH and α‐MSH receptor density and affinity suggesting that these hormones may have modulatory roles on the pattern‐related differential neural regulation of the melanophores.
Population structure, age and growth of macrourid fish from the upper slope of the Eastern‐Central Mediterranean
Authors: D'Onghia G. , Basanisi M. , Tursi A.
Published: April 2005

Hymenocephalus italicus, Nezumia sclerorhynchus and Coelorhynchus coelorhynchus were found in 80, 75 and 69% of trawl hauls carried out between 250 and 750 m on the upper slope of the Ionian Sea. The abundance of H. italicus and N. sclerorhynchus increased with depth while in C. coelorhynchus the highest densities were observed in the uppermost 500 m. In all three grenadiers the average size increased with depth. The populations had a multimodal sizefrequency distribution. In H. italicus adults were generally more represented in the population and the abundance of juveniles varied with seasons. In N. sclerorhynchus and mostly in C. coelorhynchus the bulk of the population was generally made up of small individuals the year round. In N. sclerorhynchus a seasonal pattern was shown in the depth distribution of juveniles. The sex ratio was in favour of females in larger specimens and in each bathymetric stratum. Seasonal growth was detected in the otoliths of the three species. Maximum ages were around 9 years in H. italicus and N. sclerorhynchus; 8 years in C. coelorhynchus. Although some differences have been detected in the population ecology of the three species, they are characterized by a prolonged recruitment during the year, slow growth, longevity and delayed maturity.
Relationship between the drift of macroinvertebrates and the activity of brown trout in a small stream
Authors: Giroux F. , Ovidio M. , Phillippart J.‐C. , Baras E.
Published: April 2005

Brown trout Salmo trutta were most active in a small stream at night, dusk and dawn when drift rate was highest, but correlations between hourly drift rates and the trout's activity varied substantially between individuals, between different dates for a single individual, and between different periods of the daily cycle. On some occasions, the trout were responsive to the total drift rate, either at night or during the day, and on others to the largest drifting organisms only (terrestrial organisms, adults of Ephemeroptera, Diptera and Trichoptera). The study supports the idea that trout adapt their activity pattern to the abundance of drifting prey, either as generalists towards any organism, or as specialists towards the largest ones.
Screening of DNA polymorphisms in samples of archived scales from New Zealand snapper
Authors: Adcodk G. J. , Bernal Ramázrez J. H. , Hauser L. , Smith P. , Carvalho G. R.
Published: April 2005

Primers and protocols were developed to screen effciently DNA sequence polymorphism of nuclear and mitochondrial loci in samples of dried archived scales collected over the last 50 years from the New Zealand snapper Pagrus auratus (Sparidae).
Habitat preferences of European grayling in a medium size stream, the Ain river, France
Authors: Mallet J. P. , Lamouroux N. , Sagnes P. , Persat H.
Published: April 2005

The three grayling Thymallus thymallus age‐classes had strong preferences for their local habitat in the Ain river. All age‐classes preferred high water velocities between 70 and 110 cm s‐1, confirming that grayling is a typical rheophilic species. An important intraspecific segregation regarding depth occurred, as large individuals preferred deeper water than small ones (optimal ranges=50–60, 80–120 and 100–140 cm for 0+, 1+ and adults respectively). The three age‐classes had similar preferences for small substratum articles, with optimal values between 0·5 and 16·0 mm. Preference curves were generally comparable between the two sites, despite important differences in habitat availability. It is emphasized that grayling needs various habitat conditions to achieve its entire life cycle. The increasing scarcity of this species underlines the urgency of protecting lotic habitat integrity and diversity.
Evidence for sperm transfer during sneaky mating in wild Trinidadian guppies
Authors: Matthews I. M. , Magurran A. E.
Published: April 2005

Among Trinidadian guppies Poecilia reticulata, 15% of non‐receptive females had recoverable sperm that must have come from successful sneaky matings. These results provide the first evidence that sneaky mating is a successful method of sperm transfer in wild populations of the guppy.
Seasonal changes in fast‐starts in the short‐horn sculpin: integration of swimming behaviour and muscle performance
Authors: Temple G. K. , Wakeling† J. M. , Johnston I. A.
Published: April 2005

In short‐horn sculpin Myoxocephalus scorpius, the power requirements for fast‐start swimming and the length‐specific velocity of the curvature wave travelling down the spine (Û) were not influenced significantly by acclimation to summer and winter conditions at test temperatures of 5 and 15° C. However, in‐vivo and in‐vitro muscle performance exhibited acclimation responses at 15° C. Seasonal acclimation altered the escape performance curves for power and Û significantly over a wider temperature range of 0·8–20° C. Û was significantly higher at 20° C in the summer‐ than winter‐acclimation group. The acclimation of lower levels of physiological organization at 15° C may thus serve to extend the thermal limits for escape performance in summer acclimated fish.
Osmoregulation during the development of glass eels and elvers
Authors: Birrell L. , Cramb G. , Hazon N.
Published: April 2005

Drinking rates in glass eels and elvers of the European eel increased with environmental acclimation salinity from 0·07±0·02 (FW) to 0·70±0·09 μl g‐1 h‐1 (SW) at month 1 and from 1·12±0·42 (FW) to 12·85±1·05 ± l g‐1 h‐1 (SW) at month 5. Drinking rates increased with time in both FW and SW groups. FW acclimated eels when challenged acutely with SW increased drinking rate rapidly immediately upon transfer (0–15 min) and the magnitude of this response increased with developmental time from month 1 to month 5.
Description and ontogeny of young Stolephorus baganensis and Thryssa kammalensis, two Engraulididae from Peninsular Malaysia
Authors: Sarpéadonti V. , Ponton D. , Ching Chong Ving
Published: April 2005

The morphology of the digestive system was useful to distinguish the larvae of Stolephorus baganensis and Thryssa kammalensis before the full development of their dorsal and anal fins. The relative positions of these fins, the length of the anal fin, and body depth, were good criteria for identifying individuals >10·0 mm LS. For both species, the relative growth of the ten morphometric characters studied was best explained by linear piecewise regressions indicating inflection in allometry at specific standard lengths. Most of these sudden changes in growth rate occurred between 6·9 and 10·0 mm LS for S. baganensis and between 5·8 and 8·9 mm LS for T. kammalensis. Double‐centred principal component analysis (PCA) confirmed important changes in the external morphology of both species during this transition period. Prior to this period, the main parameters characterizing the global morphological changes of both species were the length and position of dorsal and anal fins whereas they were body depth and eye diameter (only in S. baganensis) for larger specimens. Complete development of scales did not appear as a suitable criterion to define the end of the larval period, which, instead, was set at the size at which larvae presented an adult‐like pigmentation (respectively 35·0 mm LS and 55·0 mm LS in S. baganensis and T. kammalensis).
Changes in reproductive strategy in the ruffe during a period of establishment in a new habitat
Authors: Devine J. A. , Adams C. E. , Maitland P. S.
Published: April 2005

The pattern of maturation, body size and fecundity was examined in a population of ruffe (Gymnocephalus cernuusL.) three times during a period of rapid growth, and eventual stabilization, following its introduction to a new habitat. When the ruffe were less common, maturing ruffe were relatively large and immature ruffe relatively small, compared with when the ruffe were abundant. Intermediate ruffe population size showed a maturation pattern intermediate between these two extremes. It is suggested that this pattern of maturation is a response of the ruffe population to changing growth opportunity induced by changing intraspecific competition. This fluctuating maturation pattern is interpreted in terms of a threshold‐dependent maturation trigger, operating on the rate of accumulation of energy and a trade‐off between somatic growth and gonad development. When the ruffe population was large, high intraspecific competition resulted in low opportunity for growth; only fish with the highest rate of food acquisition were able to mature in a given year–the investment in gonadal tissue reducing somatic growth. When the ruffe population was low, the high rate of energy acquisition in the population resulted in the triggering of maturation, even at small size, only the very smallest fish remaining immature. High growth opportunity allowed maturing fish to develop gonad and maintain somatic growth. The pattern of size related fecundity also changed over the three periods. When growth opportunity was low, size related fecundity was greater than when opportunity for growth was high. This suggests that maturing females faced with poor growth conditions compensated by increasing egg number for a given body size either by decreasing egg size or by increasing total investment in ovarian tissue.
Pelagic early life phase of the bullhead in a freshwater lake
Authors: Wanzenböuck J. , Lahnsteiner B. , Maier K.
Published: April 2005

In June and July 1998, in Hallstättersee, Austria, late larval/early juvenile bullhead Cottus gobio L. were found in littoral and pelagic habitats, the latter representing the first record of pelagic habitat use of this species during early life history.
Phylogenetics of European cyprinids: insights from allozymes
Authors: Häunfling B. , Brandl R.
Published: April 2005

Allozyme data from 23 central European cyprinid taxa suggest that the two sub‐families Alburninae and Leuciscinae are paraphyletic. However together, both families seem to form a monophyletic group. By using a molecular clock, the radiation of this group is estimated to be as old as 20 million years. This is consistent with the fossil record. The genus Leuciscus is not monophyletic. The commonly used genus Blicca is a junior synonym to Abramis and both genera should become merged. The genus Tinca is rather distinct from the Alburninae Leuciscinae lineage and clearly does not belong to this group. These conclusions are consistent with published phylogenetic analyses of sequence data. These analyses underline that despite the developments in sequencing allozymes are a cheap and valuable tool in phylogenetics. Combining the estimate of the phylogenetic tree and biogeographic data, there was a decrease of distributional overlap when moving from the tips of the tree to the root. This pattern is consistent with sympatric speciation.