bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of daily increment deposition and early development in the otoliths of Sarotherodon melanotheron
Authors: Ekau W. , Blay J.
Published: April 2005

A one‐to‐one relationship was found between days of rearing and counted daily increments in the otoliths of Sarotherodon melanotheron verifying daily increment deposition. A marked hatch check was found in all otoliths from both the reared fish and the wild specimens. Five to 10 faint prolarval increments were visible but the rate of their formation was not investigated. The rate of increment deposition of S. melanotheron is apparently independent of somatic growth and increments found in the otoliths of this species can therefore be used for ageing.
Testis and sperm morphology in two deep‐water squaloid sharks, Centroscymnus coelolepis and Centrophorus squamosus
Authors: Girard M. , Rivalan P. , Sinquin G.
Published: April 2005

The organization of spermatocysts in the testes of 77 Centroscymnus coelolepis and 53 Centrophorus squamosus is of the diametric type. Unlike other elasmobranchs with this type of gonad, an epigonal organ was not observed. Two classes of adults (C and D stages) were distinguished according to testis shape and clasper development. D stage specimens differed from C stage as they had mated at least once. The reproductive product of male C. coelolepis seems to be unique among sharks; spermatozeugmata consist of spermatozoa aggregates and do not display clumped sperm as in C. squamosus.
Site fidelity and homing behaviour in coral reef cardinalfishes
Authors: Marnane M. J.
Published: April 2005

Tagged adult cardinalfishes Apogon doederlini, Cheilodipterus artus and Cheilodipterus quinquilineatus persisted to within an average of 36–79 cm of their initial resting positions within One Tree Reef lagoon for over 8 months in A. doederlini and over 16 months in C. artus and C. quinquilineatus. In addition, 56–81% of tagged fish displaced c. 1 km, and 33–63% of tagged fish displaced c. 2 km returned to their point of collection within 3 days. As cardinalfishes are often found densely aggregated at resting sites, their extended use of specific sites on reefs may represent a localized, predictable resource for predators and a significant source of spatial variation in nutrient input to reef systems via faeces.
Functionally distinct haemoglobins of the cryopelagic Antarctic teleost Pagothenia borchgrevinki
Authors: Riccio A. , Tamburrini M. , Carratore V. , Prisco G. di
Published: April 2005

Pagothenia borchgrevinki, has a higher haemoglobin concentration than other Antarctic notothenioids and the high oxygen capacity may correlate with the relatively active mode of life of this fish. The fish has five haemoglobins (Hb C, Hb 0, Hb 1, Hb 2 and Hb 3) with Hb 1 accounting for 70–80% of the total, and Hb C being present in trace amounts. Hb 1 and Hb 2 are functionally similar in terms of Bohr and Root effects. Hb 3 has a weaker Bohr effect than Hb 1 and Hb 2, and the Root effect is similar to that of Hb 1. Hb 0 has a strong Bohr effect and the Root effect is enhanced to a larger extent by the physiological effectors chlorides and phosphates than that of the other components with the exception of Hb C. The heats of oxygenation are lower than those of temperate fish haemoglobins. Temperature variations may have a different effect on the functional properties of each haemoglobin, and chloride and phosphates may play an important role in the conformational change between the oxy and deoxy structures. The complete amino acid sequences of Hb 1 and Hb 0, as well as partial N‐terminal or internal sequences of the other haemoglobins, have been established. The high multiplicity of functionally distinct haemoglobins indicates that P. borchgrevinki, has a specialized haemoglobin system.
A cluster of four globin genes from the Antarctic fish Notothenia coriiceps
Authors: Cocca E. , Detrich H. W. , Parker S. K. , Prisco G. di
Published: April 2005

The blood of Channichthyidae, the most phyletically derived notothenioid family, is devoid of haemoglobin (Hb). Three of the 15 channichthyid species retain inactive genomic remnants of the major adult notothenioid α‐globin gene, but have lost the gene encoding adult β‐globin. In an attempt to understand the mutational events leading to loss of globin expression in channichthyids, the organisation of globin genes in red‐blooded notothenioid species was examined. Globin genes in fish are often organised as α/β pairs linked in 5’to 5’orientation, and the major adult α‐ and β‐globins of the Antarctic yellowbelly rockcod Notothenia coriiceps have this organisation. A second globin gene cluster from N. coriiceps contains two sets of linked α‐ and β‐globin genes but the deduced amino acid sequences of the globins differ from those of the adult globins. To test the hypothesis that the globins may be expressed at different stages of ontogenesis, total RNA from head kidney and erythrocytes of adult and juvenile N. coriiceps were probed for transcripts corresponding to the four globin genes. The data suggest that the globin genes of this cluster are transcribed maximally in the early phase of development. Southern analysis of the genomes of red‐ and white‐blooded notothenioids revealed that the genes of this complex are absent in Hb‐less icefish.
Sex differences in ionoregulatory responses to dietary oil exposure in polar cod
Authors: Christiansen J. S.
Published: April 2005

Serum osmolalities and chloride concentrations were examined in polar cod. When exposed to oil male and female fish responded differently. Ingestion of food contaminated with oil led to a significant decrease in osmolality (from 503 to 492 mOsm kg−1) in males. There was no significant effect of oil ingestion on serum osmolality in females, but chloride concentrations were increased (from 196 to 203 mmol kg−1). Gender related responses should, therefore, be considered when assessing the possible effects of environmental pollutants on fish physiology.
Critical period of androgen‐inducible sex differentiation in a teleost fish, the European sea bass
Authors: Blázquez M. , Felip A. , Zanuy S. , Carrillo M. , Piferrer F.
Published: April 2005

Twenty‐day exposures to 17α‐methyltestosterone (MT) (10 mg kg‐©1 food) starting at 86 or 106 days post fertilization (DPF) resulted in a complete masculinization of sea bass Dicentrarchus labrax, as opposed to 46% females present in the controls. Earlier exposures failed to suppress ovarian development, resulting in a variable number of females (range 10·5–49·5%). All treatments assayed between 110 and 210 DPF induced a complete masculinization, regardless of the androgen or the dose tested. However, a dose dependent increase in the number of fish with intratesticular oocytes was observed after MT but not after 17α‐methyldihydrotestosterone (MDHT) administration. This might be a reflection of the capability of MT and not of MDHT to be converted into oestradiol by the action of aromatase. One hundred‐day exposures to either of the androgens (10 mg kg©1 food) starting at 60 or 160 DPF resulted in a total suppression of ovarian development and a partial induction of sterility. Complete sterility was accomplished after 200 days of exposure starting at early ontogenesis (60–260 DPF). These deleterious effects on gonadal development were later confirmed by a dramatic reduction of the gonadosomatic index. In addition, around the first year of age, growth was significantly depressed in all groups except those for which treatments started at the latest (160–260 DPF; experiment 1) or the earliest and shortest (46–66 DPF; experiment 2). Hence, the critical period of androgen‐inducible masculinization is located between 96 and 126 DPF and coincides with a rapid proliferation of primordial germ cells in the sexually undifferentiated gonad.
Assessment of cardiac output as a predictor of metabolic rate in rainbow trout
Authors: Brodeur J. C. , Dixon D. G. , McKinly R.S.
Published: April 2005

When water temperature was increased from 12 to 27°C at a rate of 2°C h−1, oxygen consumption of rainbow trout Oncorhynchus mykiss was correlated strongly with both heart rate and blood oxygen extraction but the relationship with cardiac output was variable and weak. On the other hand, when water temperature was decreased from 21 to 12°C at a rate of 0·5°C h−1, oxygen consumption was correlated with both heart rate and cardiac output but not with blood oxygen extraction. When fish were forced to swim increasingly faster, heart rate, cardiac output and blood oxygen extraction all correlated positively with oxygen consumption. For both cardiac output and heart rate, the slope of the regression line with oxygen consumption was elevated significantly more when the fish were forced to swim at increasingly higher swimming speeds than when water temperature was increased or decreased. The variation of the regression lines between cardiac output and oxygen consumption indicated that cardiac output presents few advantages over heart rate as a predictor of metabolic rate.
Climate‐related and morphoedaphic correlates of growth in white bass
Authors: Wilde G. R. , Muoneke M. I.
Published: April 2005

Length at age 1, 2 and 3 white bass Morone chrysops in 54 Texas, U.S.A., reservoirs was related significantly to longitude and log10(TDS) (total dissolved solids). Length at age 1 also was related to morphoedaphic index (MEI), mean depth, and length of growing season. Quadratic models for latitude and growing season explained 19–24% (latitude) and 24–34% (growing season length) of the variation in length of white bass. Length of all age classes was unrelated to reservoir age, maximum depth, and surface area.
Gonadotropin‐induced steroidogenic shift towards maturation‐inducing hormone in Japanese yellowtail during final oocyte maturation
Authors: Rahman M. A. , Ohta K. , Chuda H. , Nakano S. , Maruyama K. , Matsuyama M.
Published: April 2005

Intact ovarian follicles, obtained from untreated and human chorionic gonadotropin (HCG) treated Japanese yellowtail Seriola quinqueradiata during different maturational stages, were incubated with radioactive [3H]pregnenolone, [3H]17‐hydroxyprogesterone or [14C] androstenedione and steroid metabolites identified by thin layer chromatography (TLC) followed by recrystallization to constant specific activity. In untreated late vitellogenic (0 h) follicles, androstenedione was the major product with smaller amounts of testosterone and oestradiol‐17α. In post‐vitellogenic (12 h post‐injection) intact follicles, androstenedione predominated, and although testosterone and oestradiol‐17α were not produced, there were small amounts of 17, 20β‐dihydroxy‐4‐pregnen‐3‐one (17,20β‐P) and 17,21‐dihydroxy‐4‐pregnene‐3, 20‐dione (11‐deoxycortisol). In HCG‐treated fish, a steroidogenic shift resulted in the disappearance of testosterone and oestradiol‐17 coinciding with the appearance of 17, 20β‐P. During early and late final oocyte maturation FOM (24 and 36 h post‐injection), there was a five‐ to seven‐fold increase in the production of 17, 20β‐P, whereas production of 11‐deoxycortisol remained almost the same. During FOM, in addition to 17,20β‐P, its 5β‐reduced metabolite, 17,20β‐dihydroxy‐5β‐pregnan‐3‐one (5β‐17,20β‐P) was synthesized, suggesting a decrease in maturation‐inducing 17,20β‐P activity. 17, 20β,21‐Trihydroxy‐4‐pregnen‐3‐one (20β‐S) was not synthesized by ovarian fragments in Japanese yellowtail at any maturational stage. The metabolites identified on TLC during FOM were tested to evaluate their maturation‐inducing activity in an in vitro bioassay. Of the steroids tested, 17,20β‐P was the most effective inducer of germinal vesicle breakdown (GVBD), followed by 5β‐17,20β‐P. Timely synthesis of 17,20β‐P immediately prior to and during FOM as well as its great potency in inducing GVBD in vitro supports the evidence for a physiological role of 17,20β‐P as a maturation‐inducing hormone in Japanese yellowtail.
Does dispersal from landlocked trout explain the coexistence of resident and migratory trout females in a small stream?
Authors: Pettersson J. C. E. , Hansen M. M. , Bohlin T.
Published: April 2005

The hypothesis that stream‐resident females of brown trout Salmo trutta occurring in sympatry with sea‐migrant females in a small stream were immigrants from an up‐stream allopatric landlocked population was rejected. Genetic differentiation was not detected between the sympatric forms whereas they both diverged significantly from the land‐locked population, suggesting a common gene‐pool for the sympatric migratory and stream‐resident forms. Assignment tests, based on microsatellite markers, to identify the population of origin of individuals did not suggest pronounced dispersal from the landlocked population into the down‐stream population. However, it cannot be precluded that a modest degree of gene flow takes place from the landlocked population and that this may play a role in maintaining the two co‐existing life‐history forms among females in the down‐stream population.
Early life history strategies of notothenioids at South Georgia
Authors: North A. W.
Published: April 2005

Antarctic notothenioid early life history strategies are examined in general and then for common species at South Georgia. Channichthyids, bathydraconids, artedidraconids and some nototheniids have large eggs 3·0–4·9 mm whereas other nototheniids and arpagiferids have smaller eggs 1·6–2·7 mm. At South Georgia the larvae of species with large eggs hatched between August (late winter) and late November (late spring) at 11–16 mm standard length (Ls). Larvae of species with small eggs hatched mainly during October and December at 4.5–9 mm Ls. Most of the larvae of all species attain urostyle flexion between October and January, and develop to the end of the larval stage between November and May. The duration of the larval stage varies from 2 months in species with smaller larvae to 6 months for some of the species with larger larvae. Two nototheniid species develop to the early juvenile stage before a channichthyid and a bathydraconid that hatch around 2 months earlier. During their first winter, the early‐juveniles of most species with large eggs are pelagic, whereas those of species with small eggs may be pelagic or demersal. Four groups of strategies are proposed based on egg size and the winter ecotype of the early‐juvenile stage.
Semelparous or iteroparous: resource allocation tactics in the ayu, an osmeroid fish
Authors: Iguchi K. , Tsukamoto Y.
Published: April 2005

Ayu Plecoglossus altivelis is an annual osmeroid fish with a single breeding season. Its reproductive mode tends to vary such that large females spawn once, while small females spawn twice with an interval of some 2 weeks. The hypothesis was examined that certain female reproductive modes are governed by adequate resource allocation according to maternal body size, to maximize lifetime reproductive success. A series of rearing experiments revealed that immediately before spawning, larger females had relatively higher diversion from the soma and higher investment into the gonad, in contrast to smaller females which maintained higher protein synthetic activity for further reproduction. It was concluded that the extant plasticity in the reproductive mode that occurred in P. altivelis was an outcome of different tactics on the semelparity‐iteroparity continuum rather than maladaptive deviation from the optimum.
Movement of age‐1 pikeperch under the ice cover
Authors: Lappalainen J. , Vinni M.
Published: April 2005

Massive movement of age‐1 pikeperch under ice was observed in northern Lake Hiidenvesi. The size‐distributions of age‐0 and age‐1 pikeperch in different basins showed the fish movement, either passive or active, c. 3 km from one basin to another.
Survival and growth of sea trout parr in fresh and brackish water
Authors: Landergren P.
Published: April 2005

There was no di.erence in survival or growth rate over 63 days for young‐of‐the‐year sea trout Salmo trutta in fresh and brackish Baltic Sea water (6·7 psu). Hence, such sea trout parr that migrate from the freshwater habitat in which they hatch to the Baltic coastal zone, without smolting, should experience little or no physiological cost in survival and growth.
Bubble nest habitat characteristics of wild Siamese fighting fish
Authors: Jaroensutasinee M. , Jaroensutansinee K.
Published: April 2005

Siamese fighting fish Betta splendens in Thailand inhabit shallow water amongst dense emergent vegetation near the margin of rice paddy fields. Nesting water was low in dissolved oxygen, pH, salinity but high in free carbon dioxide and temperature. This fish aggregated with a mean population density of 1·7 fish m‐2 and an equal adult sex ratio. Males were heavier, longer and wider than females. The size of their bubble nest is in proportion to their weight and length.
Social status, access to food, and compensatory growth in juvenile Atlantic salmon
Authors: Maclean A. , Metcalfe N. B.
Published: April 2005

Juvenile Atlantic salmon Salmo salar subjected to three weeks of cooler temperatures were 8·5% smaller than controls at the end of the temperature manipulation, but had caught up in size 20 weeks later. The behavioural means is examined by which this catch‐up or compensatory growth is achieved. While on average compensating fish did not spend more time feeding, dominant fish within each group gained more exclusive access to the feeding area during periods of catch‐up growth. Therefore the extent to which compensatory growth could be achieved was dependent on both the social status of the individual and the dominants’ ability to monopolize the food patch.
Observations on the biology and ecology of the blue shark in the North‐east Atlantic
Authors: Henderson A. C. , Flannery K. , Dunne J.
Published: April 2005

Of 159 blue sharks Prionace glauca examined (59% female, 41% male) from oceanic waters SW of Britain and Ireland, all but two males were immature. Size‐at‐age and growth rate were similar to previous studies in the North Atlantic, while stomach contents included cephalopods, fish, cetaceans, and to a lesser degree, birds and crustaceans.
Changes in gill Na+, K+ ‐ATPase specific activity during seaward migration of wild juvenile chinook salmon
Authors: Ewing R. D. , Ewing G. S. , Satterthwaite T. D.
Published: April 2005

Migration of wild juvenile chinook salmon Oncorhynchus tshawytscha during the first 80 km of their 254 km migration through the Rogue River, Oregon, was significantly slower than that during the last 170 km. Gill Na+, K+ ‐ATPase specific activity did not increase significantly during the first 38 km of migration. Specific activities during the next 43 km did increase significantly. Specific activities continued to increase as the fish moved downstream, reaching a maximum within 44 km from the Pacific Ocean.
An evaluation of horizontal echo sounding as a method for behavioural studies of 0+ fish in field experiments
Authors: Romare P.
Published: April 2005

A 120 kHz echo sounder, with two split‐beam transducers, was used horizontally to monitor the behaviour of 0 + roach Rutilus rutilis, from June to August, in field enclosures. 0+ roach outside the vegetated area of the enclosures were registered both as schools and as single swimming fish. Combining echo counting and tracking with direct observation of echograms, an estimate of relative abundance of 0 + roach in the open water volume was obtained also. With this set up, intermediate sized field experiments studying 0 + fish, may be performed during the whole summer season.
Capacity for growth compensation in juvenile three‐spined sticklebacks experiencing cycles of food deprivation
Authors: Ali M. , Wootton R. J.
Published: April 2005

The capacity of three‐spined sticklebacks Gasterosteus aculeatus (initial mean mass 0.280 g) to compensate for recurrent periods of food deprivation of 2, 4 or 6 days followed by 2 days of ad libitum feeding on enchytraeid worms over 56 days was assessed by measuring appetite and growth. Control fish were fed daily. The total number of days on which fish were fed ranged from 14 (6‐day cycle) to 56 (controls). Deprived sticklebacks were hyperphagic on the first day of re‐feeding in a cycle and this hyperphagia increased with successive cycles. Mean daily consumption on first day of refeeding was: controls, 62.9 mg; 2 days, 108 mg; 4 days, 98.8 mg; 6 days, 101 mg. The hyperphagia did not increase as the preceding period of deprivation within a cycle increased. Hyperphagia was not maintained on the second day of re‐feeding. The 4 day and 6 day groups initially showed hypophagia on the second day of re‐feeding. Mean daily consumption on second day of re‐feeding was: controls, 62.6 mg; 2 days, 62.2 mg; 4 days, 54.2 mg; 6 days, 50.0 mg. Over the experiment, consumption on the second day of the 4 day and 6‐day groups increased towards the control level, suggesting a developing compensatory response. The highest mean daily consumption per days fed was shown by the 2 day group. The relationship between number of days fed and total food consumption and specific growth rate suggested that the 2 day group almost compensated for the periods of deprivation. Performance declined for the 4 day and 6 day groups, although even at the highest level of deprivation, a positive growth was achieved. Mean specific growth rate in mass (% per day) was: controls, 2.33; 2 days, 1.89; 4 days, 1.21; 6 days, 0.86. Initial mass and total food consumption accounted for most of the variance in specific growth rate. Other indices of performance including lipid concentration, dry matter concentration and the RNA:DNA ratio in white muscle were positively related to quantity of food consumed by each group. Growth efficiency of sticklebacks in terms of wet mass gained and wet mass consumed over the experimental period was 19.4% and did not differ among control and treatment groups. The growth rates of the sticklebacks experiencing cyclical deprivation were comparable to growth rates previously recorded for sticklebacks fed daily, but consuming similar mean daily rations.
Parental influence on early development in the European sea bass
Authors: Saillant E. , Chatain B. , Fostier A. , Przybyla C. , Fauvel C.
Published: April 2005

Fertilization, survival during incubation and hatching were highly correlated and strongly influenced by the female parent and the interaction between both parents of the sea bass Dicentrarchus labrax. A single significant male effect was detected on hatching and may reflect a genetic component determining survival from fertilization to hatching. Egg size and total length of 8‐day‐old larvae (age of first feeding) were also subjected to the influence of the female but the two parameters were not correlated. A significant interaction between both parents was also observed for length of larvae. The survival rates were significantly correlated in two consecutive years indicating that reproductive performances may be repeatable. Although the effect of the male parent on early sea bass development is shown for the first time, it seems that most of the parental effects on early performance in this species are due to females even when hormonal stimulations are performed at very close prematurational stages of oocyte development.
Intra‐annual variation in the batch fecundity of sardine off Portugal
Authors: Zwolinski J. , Stratoudakis Y. , Sares E.
Published: April 2005

Atresia in the ovaries of sardine Sardina pilchardus did not show clear seasonal patterns. There was high prevalance (c. 60%) and low intensity (c. 1% of gonadal area occupied by oocytes) in all months of the spawning season studied. The batch size to ovary‐free mass relationship was significantly different in the mid‐spawning season, with higher relative fecundity and gonadosomatic index (IG) in January than in November and March. There was no additional effect on batch fecundity due to age or condition factor. Data from monthly market samples during 1998–1999 revealed a continuous decline of the condition factor throughout the spawning season. The market samples also revealed that the duration of the spawning season is not equal for all fish. In any month, pre‐spawning fish tended to have significantly higher IG than spawners, indicating that delayed initiation of spawning can lead to larger relative fecundity. The increase in sardine relative fecundity during the first half of the spawning season is probably due to the continuous influx of new spawners and possibly to body mass loss that is initially not translated into gonad mass loss. After January when all visible fat reserves within the body cavity have disappeared, the influx of new spawners practically ceases.
Mitochondrial DNA sequence variation within and between tuna Thunnus species and its application to species identification
Authors: Takeyama H. , Chow S. , Tsuzuki H. , Matunaga T.
Published: April 2005

Restriction analysis detected two types of bigeye tuna (α and β); the α type was in the majority in the Atlantic but nearly absent in the Indo‐Pacific. The β type shared a larger number of restriction sites with other species than the conspecific β type, but bigeye‐specific nucleotide substitutions with a novel diagnostic restriction profile were found. Although the nucleotide sequence difference between Atlantic and Pacific sub‐species of the northern bluefin tuna was nearly the largest among species, individuals possessing the Atlantic type of mtDNA were found at very low frequency in the Pacific and vice versa. Previous RFLP markers were found to be diagnostic for the other five species (albacore, blackfin, longtail, southern bluefin and yellowfin tunas). Genetic information is provided to discriminate all Thunnus species regardless of their origin and to identify the ocean of capture in the northern bluefin and bigeye tunas.
Characterization of the ultrastructure of the gastrointestinal tract mucosa, stomach contents and liver enzyme activity of the pinfish during development
Authors: Gallagher M. L. , Luczkovich J. J. , Stellwag E. J.
Published: April 2005

Carnivorous juveniles (<16 mm LS) of pinfish Lagodon rhomboides apparently lacked gastric glands in the stomach while larger fish, intermediates (30‐33 mm LS) and herbivorous adults (>80 mm LS) had numerous gastric glands. Two cell types were identified in the gastric glands of larger fish: mucous secreting cells and secretory cells which had ultrastructure features typical of digestive enzymes and acid secretion. Lipid absorption occurred throughout the caeca and intestine in all sizes of fish. Microvilli found on the rectal epithelial cells of the intermediate and adult pinfish occurred on stalks and were possibly associated with water reabsorption. Liver enzyme activities changed in small fish (26–39 mm LS) compared to the adult fish. Alanine amino transferase (ALT) and fructose diphosphotase (FDP) activities declined while pyruvate kinase (PK) activities increased significantly. These changes were consistent with a change in diet from a carnivorous (high protein) diet in juveniles to an omnivorous (lower protein) diet determined by stomach content analyses.
Plasma cortisol and metabolite level profiles in two isogenic strains of common carp during confinement
Authors: Ruane N. M. , Huisman E. A. , Komen J.
Published: April 2005

A rapid increase in common carp Cyprinus carpio plasma cortisol levels was noted, in two experiments, after 30 mins of a 3 h net confinement, which was sustained while the fish were held in the nets. After release from the nets, cortisol levels returned to control values in 1 h. Plasma glucose and free fatty acid levels were elevated by the confinement. Glucose was increased after 30 min but returned to basal levels after 22 h of recovery while free fatty acids were not elevated until 3 h of confinement and remained high for the duration of the recovery period. After confinement for 3 h, plasma lactate levels were reduced and remained low for a further 1 h. No change in either plasma triglyceride or cholesterol levels were found during the study. Confinement had no effect on haematocrit levels but blood haemoglobin levels were reduced. In both experiments hypochloraemia occurred in response to confinement. However, values returned to pre‐confinement levels 22 h after confinement. These results show that rearing isogenic carp strains, under identical conditions, results in a reproducable response to an acute stressor and that these carp respond in a similar manner to other teleost species.
Survival, development and food energy partitioning of nase larvae and early juveniles at different temperatures
Authors: Keckeis H. , Kamler E. , Bauer‐Nemeschkal E. , Schneeweiss K.
Published: April 2005

Survival was generally high, 94–100%, for newly hatched larvae of the nase Chondrostoma nasus held at 10, 13, 16, 19, 22, 25 and 28° C up to day 66 post‐fertilization. The developmental rate decreased with age and increased with temperature. Specific growth rates increased with temperature; within one temperature range growth rate decreased with ontogenetic development. Food consumption and respiration increased with temperature and body size. A temperature increase from 25 to 28° C resulted in slightly reduced survival, minor acceleration of developmental growth and respiration rates, and impeded skeleton formation. Growth efficiency of consumed energy decreased throughout the larval period from 55 to 67% at the first larval stage (L1) to 36–48% at the first juvenile stage (J1). A similar trend for assimilation efficiency and its utilization for growth was observed. The constant temperatures required by larval nase ranged from a minimum 8–10° C to a maximum 25–28° C. A shift of optimum temperatures, 8–12, 13–16, 15–18, 19 and 22° C for nase spawning, embryonic development, yolk feeding larvae, early externally feeding larvae and, late larvae and juveniles, respectively, paralleled the spring rise in the river water temperature. Larval and juvenile nase show high survival, growth and energy conversion efficiencies compared with other fish species. On the other hand, low survival rates and growth can be attributed to external perturbations; thus, young nase may be considered a good indicator of the environmental and ecological integrity of river systems.
Growth and nutritional trials on transgenic Nile tilapia containing an exogenous fish growth hormone gene
Authors: Rahman M. A. , Ronyai A. , Engidaw B. Z. , Jauncey K. , Hwang G‐L. , Smith A. , Roderick E. , Penman D. , Varadi L. , Maclean N.
Published: April 2005

In a long‐term growth trial, transgenic tilapia Oreochromis niloticus L. showed a 2·5‐fold increase in growth compared with non‐transgenic siblings. At 7 months, mean mass of transgenic tilapia was 653 g compared with 260 g for non‐transgenic siblings. A significant increase (P >0·01) in head: total length ratio, viscera‐somatic index and hepato‐somatic index was observed in transgenic fish. Female gonado‐somatic index (I G) was found to be lower in transgenics than non‐transgenic siblings in both mixed and separate culture conditions. Transgenic male I G values were found to be higher in mixed culture and lower in separate culture than that of their non‐transgenic siblings. Food conversion efficiency was more than 20% greater in the transgenic fish. In a second shorter‐term growth performance trial, the transgenic fish grew to about four times the size of their non‐transgenic siblings. A digestibility trial suggested that transgenic tilapia were more efficient utilizers of protein, dry matter and energy. Apparent digestibility of protein and apparent energy digestibility were higher in the transgenic fish.
Two new species of snailfish genus Paraliparis (Pisces: Liparidae) from the Ross Sea, Antarctica
Authors: Chernova N. V. , Eastman J. T.
Published: April 2005

Two new species of Liparidae (snailfish) Paraliparis macrocephalus sp. nov. and P. rossi sp. nov., captured in the south‐western Ross Sea, Antarctica (74–75° S; 165–171° E), are described and illustrated. Paraliparis macrocephalus resembles, but is distinct from P. hubbsi, P. valentinae, P. somovi and P. aspersus. Paraliparis rossi is similar to P. macrocephalus in meristic counts, pectoral girdle structure and morphometry but differs in size of cephalic pores and nostril, shape of teeth, colour and other characters. Paraliparis macrocephalus was captured in the deepest locality in the Ross Sea, the Drygalski Trough, a 1200 m deep inner‐shelf depression. As trawling was preceded by video camera tows, a description of the substratum and fauna of these little‐studied trough habitats is also provided.
Somatostatin inhibits growth of rainbow trout
Authors: Very N.M. , Knutson D. , Kittilson J. D. , Sheridan M. A.
Published: April 2005

Implantation of rainbow trout Oncorhynchus mykiss with somatostatin‐14 (SS‐14) for 20 days resulted in reduced food conversion as well as significant growth retardation compared to controls. Relative growth as mass was reduced by 20%, whereas relative growth by length was reduced by 45%. A single intraperitoneal injection of SS‐14 reduced plasma levels of growth hormone (GH), insulin‐like growth factor‐1 (IGF‐I) and insulin. SS‐14 injection also reduced [35S]‐sulphate incorporation into gill cartilage compared to saline‐injected fish. In addition, in vitro incubation of gill cartilage with SS‐14 reduced [35S]‐sulphate incorporation in a doserelated manner. These results indicate that SS‐14 inhibits growth of rainbow trout and suggests that SS‐14, in addition to influencing GH, may play an extra‐pituitary role in the modulation of the GH‐IGF‐I axis.
Stress from air emersion fails to alter chloride cell numbers in the gills of rainbow trout
Authors: Sloman K. A. , Taylor A. C. , Metcalfe N.B. , Gilmour K. M.
Published: April 2005

Air emersion stress caused an elevation in blood plasma cortisol of rainbow trout Oncorhynchus mykiss but this acute stressor did not elicit chloride cell proliferation in the gill tissue within 2 weeks following the disturbance.
Non‐competitive coexistence between Mediterranean grey mullet: evidence from seasonal changes in food availability, niche breadth and trophic overlap
Authors: Cardona L.
Published: April 2005

Five grey mullet species in the Albufera des Grau lagoon (Balearic Islands, Western Mediterranean), reacted to the spring‐summer reduction in the organic matter content of sediment by expanding their niche breadth, mainly due to higher algae consumption. However, trophic overlap did not change for most of the studied species pairs and when it did, overlap was higher in the warm than in the cold season. When all the assemblage was considered, niche overlap distribution was significantly skewed towards values higher than those predicted by null models, both in the warm and the cold season. These results are not consistent with the predictions from the niche theory, which suggests that grey mullet are under carrying capacity and hence competitive exclusion does not operate in the studied assemblage.
Marking pike fry otoliths with alizarin complexone and strontium: an evaluation of methods
Authors: Skov C. , Grønkjær P. , Nielsen C.
Published: April 2005

Laboratory experiments demonstrated that both alizarin complexone and strontium are useful in mass marking of pike Esox lucius fry otoliths. Visual detection of alizarin complexone marks was considered more reliable than the quantitative analysis of strontium for differentiating marked and unmarked individuals after release in a Danish lake.
Cardiorespiratory status of triploid brown trout during swimming at two acclimation temperatures
Authors: Altimiras J. , Axelsoon M. , Claireaux G. , Lefrançois C. , Mercier C. , Farrell A. P.
Published: April 2005

At 14° C, standard metabolic rate (75·1 mg O2 h−1 kg−1), routine metabolic rate (108.8 mg O2 h−1 kg−1), active metabolic rate (c. 380 mg O2 h−1 kg−1), critical swimming speed (Ucrit 1·7 BL s−1), heart rate 47 min−1), dorsal aortic pressure (3·2 kPa) and ventilation frequency (63 min−1) for triploid brown trout Salmo trutta were within the ranges reported for diploid brown trout and other salmonids at the same temperature. During prolonged swimming (c. 80%Ucrit), cardiac output increased by 2·3‐fold due to increases in heart rate (1·8‐fold) and stroke volume (1·2‐fold). At 18° C, although standard and routine metabolic rates, as well as resting heart rate and ventilation frequency increased significantly, active metabolic rate and certain cardiorespiratory variables during exercise did not differ from those values for fish acclimated to 14° C. As a result, factorial metabolic scope was reduced (2·93‐fold at 18° C v. 5·13‐fold at 14° C). Therefore, it is concluded that cardiorespiratory performance in triploid brown trout was not unusual at 18° C, but that reduced factorial metabolic scope may be a contributing factor to the mortality observed in triploid brown trout at temperatures near 18° C.
Ultrastructure of Thunnus thynnus and Euthynnus allettevatus spermatozoa
Authors: Abascal F. J. , Medina A. , Megina C. , Calzada A.
Published: April 2005

The spermatozoa of Thunnus thynnus and Euthynnus alletteratus consist of an acrosome‐less head (comprising the ovoid nucleus and the short midpiece) and a long flagellar tail that contains the conventional 9 + 2 axoneme and lacks lateral fins. The centrioles are arranged at approximately right angles and lie outside of a shallow nuclear groove. The flagellum inserts laterally on the nucleus, therefore the spermatozoon is asymmetrical. The midpiece contains a few mitochondria which are separated from the axoneme by the cytoplasmic canal; they are spherical in T. thynnus and elongate, somewhat irregular in E. alletteratus. Although the main ultrastructural characteristics of the spermatozoa appear to indicate a great homogeneity in the sperm morphology within the family Scombridae, small species‐specific divergences may be of use in systematics.
Reproductive ecology of Japanese anchovy off the Pacific coast of eastern Honshu, Japan
Authors: Funamoto T. , Aoki I.
Published: April 2005

Spawning frequency of offshore migrant populations of Japanese anchovy Engraulis japonicus ranged from 0·34 to 0·90, and was higher than that of inshore Japanese anchovy. In addition, spawning frequency of offshore populations varied in response to the sex ratio. They spawned at water temperatures of 5.0, 8.6 and 12.6° C, indicating that the minimum critical water temperature of offshore Japanese anchovy was considerably lower than that of inshore populations. A significant positive relationship was observed between water temperature and relative batch fecundity of offshore Japanese anchovy. Furthermore, water temperature was negatively related to egg size, suggesting a trade‐o. between relative batch fecundity and egg size for offshore fish. At the same water temperature, relative batch fecundity of offshore populations was higher than that of inshore ones. The comparison of spawning frequency and relative batch fecundity suggests that offshore Japanese anchovy represent a reproductive ecology by which they spawn more eggs than inshore Japanese anchovy within a certain time period.
Stereological assessment of the reproductive status of female Atlantic northern bluefin tuna during migration to Mediterranean spawning grounds through the Strait of Gibraltar
Authors: Medina A. , Abascal F. J. , Megina C. , García A.
Published: April 2005

The ovarian mass and gonadosomatic index (IG) of bluefin tuna Thunnus thynnus, caught in the Strait of Gibraltar (Barbate) during migration to Mediterranean spawning grounds, were several times lower than those found in bluefin tuna from Mediterranean spawning grounds (Balearic Islands). Some of the bluefin tuna from Barbate (8.3%) were classified as immature (the most advanced oocytes present in the ovaries were early vitellogenic), and the majority (the remaining 91.6%) as non‐spawning mature; the ovary contained late vitellogenic oocytes, but there was no sign of spawning activity. Stereological estimation indicated that the ovaries of spawning bluefin tuna from the Balearic Islands contained five‐fold more highly yolked oocytes than bluefin tuna from Barbate. When breeding bluefin tuna cross the Strait of Gibraltar the gonad is at an incipient stage of maturation. The average batch fecundity estimated from stereological quantification of stage 4 (migratory‐nucleus) oocytes in the specimens collected from Balearic was 92.8 oocytes g‐1‘of body mass, and the spawning frequency in this area was calculated to be 1.2 days. In specimens from Barbate a relative batch fecundity of 96.3 oocytes g ‐1 was estimated using stage 3 (late vitellogenic) oocyte counts.
The evaluation of passive integrated transponder (PIT) tags and visible implant elastomer (VIE) marks as new marking techniques for the bullhead
Authors: Bruyndoncx L. , Knaepkens G. , Meeus W. , Bervoets L. , Eens M.
Published: April 2005

To test the reliability of PIT tags and VIE marks as new marking techniques for the bullhead Cottus gobio, different tagging treatments were assayed. The relatively high recapture rates suggest the applicability of both marking techniques for this small benthic fish species.
The tilapiine fish stock of Lake Victoria before and after the Nile perch upsurge
Authors: Goudswaard P. C. , Witte F. , Katunzi E. F. B.
Published: April 2005

Since the beginning of fisheries in Lake Victoria, two native tilapiine species,Oreochromis esculentusandOreochromis variabilis, were the main target of the local fishermen. A continuous increase in fishing pressure led initially to a declining catch per unit of effort, and a smaller average fish size; eventually, there was a reduced landing of tilapiines. To boost the fisheries, three alien tilapiine species and the Nile perchLates niloticuswere introduced. Thirty years after its introduction,Oreochromis niloticusappeared to be the most successful tilapiine species. It replaced the indigenous tilapiines almost completely before the Nile perch came to dominate the ecosystem of Lake Victoria. Reduced fishing pressure on the tilapiines in the 1980s, due to the shift of the local fishery towards the Nile perch, resulted in an increase in the stock ofO. niloticusand an increase in average fish size. Subsequently, the total mass ofO. niloticuslanded increased. The stocks of the indigenous tilapiines did not recover but declined to extremely low levels, or vanished from the main lake. Currently, these species still occur in satellite lakes of Lake Victoria, from whichO. niloticusis absent. Nile perch feed onO. niloticus;however, the limited overlap in distribution between piscivorous Nile perch andO. niloticusof consumable sizes is probably an important factor in explaining the coexistence of the two species. The main cause of the disappearance of the native tilapiine species is presumed to be competitive dominance byO. niloticus.
Effect of temperature on swimming performance of sea bass juveniles
Authors: Koumoundouros G. , Sfakianakis D. G. , Divanach P. , Kentouri M.
Published: April 2005

At four temperatures (T= 15, 20, 25 and 28° C) swimming performance of Dicentrarchus labrax was significantly correlated with total length (23–43 mm LT); r2=0.623–0.829). The relative critical swimming speed (RUcrit=UcritLT−1), where Ucrit is the critical swimming speed, was constant throughout the LT range studied. The significant effect of temperature on the relative critical swimming speed was described binomially: RUcrit=−0.0323T2+ 1.578 T−10.588 (r2=1). The estimated maximum RUcrit (8.69 LT s−1) was achieved at 24.4° C, and the 90% performance level was estimated between 19.3 and 29.6° C.
Evidence for genetic differences in the offspring of two sympatric morphs of Arctic charr
Authors: Klemetsen A. , Elliott J. M. , Knudsen R. , Sørensen P.
Published: April 2005

The sub‐arctic Lake Fjellfrøsvatn, northern Norway, has two morphs of Arctic charr that are reproductively isolated because they spawn 5 months apart. The smaller morph (≤14 cm LF) is confined to the profundal zone of the lake and the larger morph is mainly littoral. Three hypotheses were tested: (i) the offspring of the profundal Arctic charr grow slower than the offspring of the littoral Arctic charr under identical conditions, thus indicating a genetic basis for the slow growth of the profundal Arctic charr in the wild; (ii) the wild phenotypes of the two morphs are morphometrically different and the differences are persistent in the offspring; (iii) the offspring of the two morphs have different behaviour traits under similar treatments. The first hypothesis was rejected; offspring of the profundal morph grew slightly better than offspring of the littoral morph at 10° C in the laboratory. The second and third hypotheses were supported by the data. Wild‐caught fish of the two morphs differed in several morphometric characters and most of the differences persisted in the offspring. In the laboratory, offspring of the littoral morph were more active, more aggressive and more pelagic than offspring of the profundal morph and naive offspring of the profundal morph were more effective in eating live chironomid larvae than were offspring of the littoral morph. The data for morphometry and behaviour, but not growth, provide evidence for genetic differences between the two Arctic charr morphs of Fjellfrøsvatn.
Morphogenesis of blood cell lineages in channel catfish
Authors: Fijan N.
Published: April 2005

The morphogenesis of blood cell lineages in channel catfish Ictalurus punctatus, from head and trunk kidney and spleen imprints as well as from blood smears of bled and control fish, showed that early maturation stages resembled those in higher vertebrates. The erythroid lineage consisted of the proerythroblast, erythroblasts (basophilic, polychromatic, orthochromic), young erythrocyte and erythrocyte. The rare bilobed erythrocyte seemed to be a cell in apoptosis while old erythrocytes and erythroplastids represented remnants of this process. Maturation stages of neutrophils and basophils encompassed the granuloblast, young progranulocyte, progranulocyte and metagranulocyte. The basophilic lineage was regularly present in kidneys, rare in spleen and absent from blood. It contained large Sudan Black and PAS‐negative, water soluble granules and small PAS‐positive ones. Lymphocytes with azurophilic granulation occured regularly in kidneys and spleen. Monoblasts and promonocytes in kidneys preceded monocytes. A phagocytic lineage devouring apoptotic blood cell remnants was present in kidneys and spleen. Its youngest identified stage (promacrophage) resembled more a granuloid cell without granules than a monocytoid one. The larger, young macrophages contained a few to several ingestions and the very large mature macrophages were loaded with them. The latter two stages corresponded to cells in melano‐macrophage centres (macrophage aggregates). Precursor stages of the thrombocyte were not identified.
The swimming abilities of recently settled post‐larvae of Sillaginodes punctata
Authors: Jenkins G. P. , Welsford D. C.
Published: April 2005

Sixty‐four post‐larvae of the King George whiting Sillaginodes punctata were tested in swimming chambers, against one of five flow‐through velocities (2, 4, 6, 8 or 10 cm s −1) for up to a maximum of 120 min. Fish were determined by regression to have an FV50 (50% fatigue velocity) of 6.0 cm s−1. No fish survived the full 120 min at 10 cm s−1. Sixteen individuals were tested in a swimming chamber against a flow‐through velocity of 6 cm s −1 and allowed to swim to exhaustion. Fish swam between 25 and 538 min with a peak at c. 6–8 h. Total swimming time was not correlated with standard length of fish although the size range examined was narrow. Relative to recent studies on the swimming abilities of late‐stage larvae of reef fishes, this study indicates that post‐larval King George whiting are weak swimmers. The weak swimming ability of post‐larval King George whiting is consistent with studies showing passive dispersal and recruitment of this species.
A somatic mosaic of the gynogenetic Amazon molly
Authors: Lamatsch D. K. , Schmid M. , Schartl M.
Published: April 2005

Breeding experiments with the gynogenetic Amazon molly, Poecilia formosa, proved that mosaicism, detected by flow cytometry with the fluorescent dye DAPI was restricted to the soma, and that gynogenetic reproduction was maintained by the offspring. Potential pathways for how mosaicism might have arisen in P. formosa are discussed.