bluuebunny/crossref_metadata_2025 huggingface dataset:
Wood‐eating catfishes of the genus Panaque: gut microflora and cellulolytic enzyme activities
Authors: Nelson J. A. , Wubah D. A. , Whitmer† M. E. , Johnson E. A. , Stewart D. J.
Published: April 2005

Fresh gut contents of the wood‐eating loricariid Panaque and a generalized loricariid Liposarcus sp. had enzymatic activity directed against both cellulose and hemicellulose. Aerobic cultures made from the guts of Panaque exhibited growth on a minimal salts medium containing only crystalline cellulose as a carbon source as well as on a variety of other substrates containing carbon polymers found in wood. Anaerobic cultures made from Panaque guts only grew with glucose as a carbon source. Cultures of whole gut contents grown on a yeast extract basal salts medium had significant cellulolytic activity. However, no culture of individual microbes had significant cellulolytic activity, suggesting that any cellulose breakdown which occurs in loricariid guts is by a consortium of micro‐organisms. A variety of aerobes, microaerophiles and facultative anaerobes were found in the guts of Panaque; several of these bacteria appear to be new species.
Development of the pectoral, pelvic, dorsal and anal fins in cultured sea bream
Authors: Faustino M. , Power D. M.
Published: April 2005

The pectoral fin girdle was the first element of the fins to develop in Sparus aurata. By 3·1mm LN (notochord length) the cleithrum was ossified and the cartilaginous caracoid‐scapula was present. The fin was fully developed at 11·6 mm LS (standard length) and by 16·0 mm LS most elements of the fin were ossified. The pelvic fins were the last pair to develop and rudiments of these were first detected at 7·9 mm LS. The pelvic fin and girdle were completely formed and ossified at 16·0 mm LS. The development of dorsal and anal fins began at c. 6·5–7·0 mm LS with the formation of 10 cartilaginous dorsal proximal radials and eight cartilaginous ventral proximal radials. The three cartilaginous predorsals (supraneurals) appeared at 7·7 mm LS and the ossification of dorsal and anal proximal and distal radials began, respectively, at 10·5 mm LS and 11·3 mm LS. Ossified structures in the fins were also classified according to their origin, as being either dermal or endochondral. Finally the chronology of appearance of fin structures in S. aurata was compared with that reported for other Sparidae, Engraulidae and Haemulidae.
Genetic characterization of a pure relict population of Oreochromis esculentus, an endangered tilapia
Authors: Agnése J.‐F. , Adépo‐Gourène B. , Owino J. , Pouyaud L. , Aman R.
Published: April 2005

Genetic variation of the Oreochromis esculentus population from Lake Kanyaboli was studied using 24 allozyme loci and three microsatellite loci and compared with four populations of O. niloticus. Results strongly suggest that this population can be considered as pure.
Parental energy expenditure of the male three‐spined stickleback
Authors: Smith C. , Wootton R. J.
Published: April 2005

The energy expenditure of male three‐spined sticklebacks performing parental care was 12·3 and 9·9 J g−1h−1estimated by respirometry and ration manipulation, respectively. The energy expenditure of caring male sticklebacks was significantly higher than for non‐caring males.
Post‐hatching development of the gut and lateral muscle in the sole
Authors: Veggetti A. , Rowlerson A. , Radaelli G. , Arrighi S. , Domeneghini C.
Published: April 2005

At hatching the gut of sole Solea solea was a primitive epithelial tube which showed vigorous cellular proliferation but only initial regionalization, and no secretory cells. By contrast, at this stage lateral muscle already consisted of a clearly distinct superficial monolayer of parvalbumin‐negative fibres, and a deeper layer of parvalbumin‐positive (presumptive fastwhite) fibres. There were no very small‐diameter fibres present and very few proliferating cell nuclear antigen (PCNA)‐positive nuclei, indicating that new fibres were not being produced at this time. The gut consisted of a distinct pharynx, oesophagus, stomach and intestine by 12 days, further differentiation of the anterior and posterior intestine was seen at 21 days, and morphological differentiation was complete at 2.5 months. Goblet cells containing acidic glycoconjugates were present at 12 days in the pharynx, oesophagus and anterior intestine, and increased in number at later ages. Neutral glycoconjugates first appeared in absorptive (not goblet) cells at 21 days. From 2.5 months neutral glycoconjugates were found in secretory cells throughout all parts of the gut except the stomach and the oesophagus, and by the adult stage the neutral glycoconjugates were the predominant type in the intestinal goblet cells. The difference in parvalbumin expression between the superficial (negative) and deep (positive) muscle layers seen at hatching persisted at all ages, and from 21 days immunostaining for slow isoforms of myosin gave a positive reaction in the superficial monolayer and subsequent slow muscle layer. Hypertrophic growth continued up to the largest subject examined, by posthatching myogenesis occurred in two distinct and relatively brief phases. The distribution of very small diameter muscle fibres and PCNA‐positive nuclei indicated that muscle hyperplasia occurred initially in apical areas of the myotomes (at 12 and 21 days), but this was followed (at 2.5 months) by a second ‘mosaic’ phase of myogenesis as new fibres appeared scattered throughout the deep muscle layer. Hyperplastic growth had ceased by 1 year.
Cardiovascular responses of eggs, embryos and alevins of Atlantic salmon and rainbow trout to nitric oxide donors, sodium nitroprusside and isosorbide dinitrate, and inhibitors of nitric oxide synthase, N‐nitro‐l‐arginine methyl ester and aminoguanidine, following short‐ and long‐term exposure
Authors: Eddy F. B. , McGovern L. , Acock N. , McGeer J. C.
Published: April 2005

Atlantic salmon embryos and alevins Salmo salar that had been exposed to isosorbide dinitrate (ISDN) for 4 weeks, on transfer to fresh water, showed an increase in heart rate. Unexposed embryos and alevins showed a decrease in heart rate following transfer to 100 μmol l−1 ISDN for 4 h. This is in contrast to adult rainbow trout and higher vertebrates where tachycardia occurred in response to nitric oxide (NO) donors. The decreased heart rate in response to ISDN was inhibited by 2 mg 1−1 methylene blue, indicating that NO activates cardiovascular events via guanylyl cyclase and cyclic guanidine monophosphate. Heart rate of rainbow trout alevins Oncorhynchus mykiss exposed to 100 μmol l−1 aminoguanidine responded with a slowly developed but significant bradycardia over 10 min as did those reared in aminoguanidine for 4 weeks then transferred to fresh water. A potentiated increase in heart rate on exposure to the NO donor sodium nitroprusside (SNP), occurred within 1 min in salmon alevins reared in l‐nitro‐arginine methyl ester (l‐NAME) for 4 weeks, indicating up‐regulation of NO receptors. The evidence for down‐regulation of SNP‐reared alevins exposed to l‐NAME was less well defined. The results suggest that both salmonid embryos and alevins have a functional l‐arginine‐NO pathway and that NO has a physiological role in control of cardiovascular events.
Heterochrony in skeletal development and body size in progeny of two morphs of Arctic charr from Thingvallavatn, Iceland
Authors: Eiríksson G. M. , Skúlason S. , Snorrason S. S.
Published: April 2005

Planktivorus Arctic charr had larger eggs than small benthivorous charr and the progeny of the former were longer (total length) at days 125, 145 and 159 after fertilization. Size differences remained significant after the removal of egg size effect on embryo size. Size of hybrid progeny tended to be similar to their maternal pure progeny group, suggesting maternal effects not directly related to yolk volume. In general, fin ray number increased faster in small benthivorous charr progeny than in planktivorous charr progeny, hybrid progeny tending to have intermediate fin ray numbers. The results indicate that morph differences in embryonic growth and skeletal development have a genetic and maternal component. Results support the hypothesis that in the period from hatching until just after first external feeding small benthivorous charr allocate more energy towards bone development, e.g. formation of fin rays, while planktivorous charr allocate more energy to body growth. The different developmental trajectories may reflect adaptations to discrete differences in habitats between the morphs.
The gill of fish larvae. Is it primarily a respiratory or an ionoregulatory structure?
Authors: Rombough P. J.
Published: April 2005

Based on surface area and chloride cell number, rainbow troutOncorhynchus mykissgills appear initially to be more important in terms of ion balance than gas exchange. Chloride cells appear on the gill 3–6 days before hatch at 10°C. This is about 9 days before secondary lamellae, the definitive adult gas exchange structure, begin to form. At hatch, 22% of all chloride cells but only 7% of total surface area are located on the gill. This discrepancy gradually diminishes but even at complete yolk absorption the gill still seems to be about twice as important in terms of ion balance (75% of chloride cells) as gas exchange (37% of total surface area represented by gill filaments and lamellae combined). Surface area measurements and chloride cell counts reported in the literature for larvae of other species show a similar pattern suggesting that this may be a general phenomenon. If true, the implications are profound not only for developmental physiologists but also for those interested in the evolutionary history of gills and their function in adult fish.
Radio‐transmitted electromyogram signals as indicators of swimming speed in lake trout and brown trout
Authors: Thorstad E. B. , ØKland F. , Koed† A. , McKinley R. S.
Published: April 2005

Swimming speed and average electromyogram (EMG) pulse intervals were highly correlated in individual lake trout Salvelinus namaycush (r2=0·52–0·89) and brown trout Salmo trutta (r2=0·45–0·96). High correlations were found also for pooled data in both lake trout (r2=0·90) and brown trout of the Emå stock (r2=0·96) and Lærdal stock (r2=0·96). The linear relationship between swimming speed and average EMG pulse intervals differed significantly among lake trout and the brown trout stocks. This successful calibration of EMGs to swimming speed opens the possibility of recording swimming speed of free swimming lake trout and brown trout in situ. EMGs can also be calibrated to oxygen consumption to record energy expenditure.
Age and growth of Mediterranean albacore
Authors: Megalofonou P.
Published: April 2005

Estimated ages of 1136 individual albacore Thunnus alalunga (57–92 cm LF) from the Aegean and Ionian Sea ranged from 1+ to 9 years. Males grew faster and reached a greater size and age than females. No significant differences were found in the mean lengths at estimated ages between the two sampling areas. The von Bertalanffy growth model was fitted to mean lengths of estimated ages of individual fish and estimated growth parameters for the combined sexes were: L∞=94·7 cm, K=0·258, to=–1·354 years. Significant differences were found when the Mediterranean albacore growth parameters were compared with those determined for Atlantic Ocean albacore. It is not possible to determine if the differences in growth rates for the two populations are phenotypic or genotypic at the present time.
Biosynthesis of ascorbic acid by extant actinopterygians
Authors: Moreau R. , Dabrowski K.
Published: April 2005

Polypterus senegalus, the longnose gar Lepisosteus osseus and the bowfin Amia calva had gulonolactone oxidase activity in the kidney and thus can synthesize ascorbic acid de novo. The enzyme activity was associated with the microsomal fraction. The common carp Cyprinus carpio and the goldfish Carassius auratus had no gulonolactone oxidase activity. Antibodies directed against white sturgeon gulonolactone oxidase showed cross‐reactivity with lake sturgeon, bowfin and longnose gar kidney enzymes, but not with enzymes from Polypterus, sea lamprey, and tadpole kidney or pig liver. Given cross‐reactivity, gulonolactone oxidase relatedness matched actinopterygian phylogeny, and suggested homology of the character throughout fishes. Modern teleosts may have lost the ability to synthesize ascorbic acid since the late Triassic as a result of a single reversal in the founding population. Wild bowfin and longnose gar exhibited high ascorbate concentrations in liver and spleen when compared with the teleosts rainbow trout Oncorhynchus mykiss and common carp fed vitamin C‐supplemented diets.
Effect of body size on the standard metabolism of horse mackerel
Authors: Herrmann J‐P. , Enders E. C.
Published: April 2005

The routine metabolic rate RR and standard metabolic rate RS were measured in horse mackerel Trachurus trachurus at 13°C over weight range of 1·4–390 g. A data extraction method rather than the more commonly used method of extrapolating the swimming speed‐metabolic rate curves back to zero swimming speed was developed to measure the RS. The relation between RR and RS and weight was expressed as a linear regression with the log transformed data. The mean slope of the regression was 0·752 for RS and 0·725 for RS.
Helminth parasite communities of the conger eel in the estuaries of Arousa and Muros (Galicia, north‐west Spain)
Authors: Sanmartín M. L. , Alvarez M. F. , Peris D. , Iglesias R. , Leiro J.
Published: April 2005

The nematodes Cucullanus hians, Cucullanus longispiculum, Cucullanus minutus, Contracaecum sp., Anisakis simplex, and Cristitectus congeri, the cestodes Grillotia, sp. and Scolex pleuronectis, and the acanthocephalan Acanthocephaloides propinquus, were recorded from 251 conger eels from the Muros and Arousa estuaries, north‐west Spain. Several species were useful as tags and showed that conger eels in both estuaries and also on the continental shelf belong to separate populations. The nematode C. congeri, shows a distribution pattern indicating that the trophic chains involving the conger eel in each estuary are probably different. The species composition and abundance of the nematode, cestode and acanthocephalan fauna of Conger conger, on the north‐west Spanish coast may depend more on population isolation and variations in trophic chains between the sites studied than on the particular environmental conditions of the sites.
Discrepancies between otoliths of larvae and juveniles of the American eel: is something fishy happening at metamorphosis?
Authors: Cieri M. D. , McCleave J. D.
Published: April 2005

The use of otoliths to interpret early life history in fishes depends upon the assumptions that otoliths record past events accurately and consistently and that records of events in otoliths are continuous. Both the number of growth microincrements (I), and the radii (R,μm) of otoliths of American eel Anguilla rostrata, leptocephali increased linearly and highly significantly with leptocephalus body length (L, mm), as expected on the above assumptions (I, =2·29 L, − 5·75 and R, =1·05 L, + 12·02, r2,=0·938 and 0·931, n, =20). In contrast, the number of increments and the radii of the leptocephalus growth zones of otoliths of glass‐phase American eels were not related to body length, and they were lower than predicted by the relationships developed for leptocephali. Thus, otoliths of American eels apparently violate one or both assumptions. Possibly, the margin of the otolith is resorbed during metamorphosis from leptocephalus to glass eel, perhaps as part of calcium metabolism as skeletal elements are being formed.
Annual movement and migration of adult pikeperch in a lowland river
Authors: Koed A. , Mejlhede P. , Balleby K. , Aarestrup K.
Published: April 2005

The downstream migration of 46–66 cm radio‐tagged adult pikeperch Stizostedion lucioperca, in the River Gudenaa, Denmark, from late September to late December, coincided with a reduction in the frequent occurrence of prey fish in the tagging area, and hence was interpreted as a feeding migration. The upstream migration from March to mid‐April in spring took place prior to spawning which occurred from late April to June.
Extensions to the known range of the whitefin gudgeon to Europe and biogeographical implications
Authors: Freyhof J. , Scholten M. , Bischoff A. , Wanzenböck J. , Staas S. , Wolter C.
Published: April 2005

In 1998 and 1999, the whitefin gudgeon Gobio albipinnatus was common in the Rivers Rhine, Elbe and in the Lower Odra.
Microsatellite variation in marine, freshwater and anadromous fishes compared with other animals
Authors: DeWoody J. A. , Avise J. C.
Published: April 2005

From a total of 524 microsatellite loci considered in nearly 40 000 individuals of 78 species, freshwater fish displayed levels of population genetic variation (mean heterozygosity, h=0·46, and mean numbers of alleles per locus, a=7·5) roughly similar to those of non‐piscine animals (h=0·58 and a=7·1). In contrast, local population samples of marine fish displayed on average significantly higher heterozygosities (h=0·79) and nearly three times the number of alleles per locus (a=20·6). Anadromous fish were intermediate to marine and freshwater fish (h=0·68 and a=11·3). Results parallel earlier comparative summaries of allozyme variation in marine, anadromous, and freshwater fishes and probably are attributable in part to differences in evolutionarily effective population sizes typifying species inhabiting these realms.
Physiological stress responses to confinement in diploid and triploid Atlantic salmon
Authors: Sadler J. , Pankhurst N. W. , Pankhurst P. M. , King H.
Published: April 2005

Confinement of juvenile Atlantic salmon Salmo salar from four different populations (all–female diploids, all–female triploids, mixed sex diploids and mixed sex triploids) either before (FW parr) or after (SW smolts) transfer to sea elevated plasma cortisol and plasma lactate from control levels irrespective of ploidy status. Both before and after confinement, plasma cortisol levels in SW smolts (6–174 ng ml–1) were higher than those in FW parr (4–58 ng ml–1), which possibly reflected the physiological challenge of acclimation to SW. Mixed sex populations of SW smolts had higher cortisol levels than all–female populations. The duration of confinement (1, 3 or 6 h) affected the magnitude of the plasma cortisol and lactate responses in SW smolts. Plasma cortisol levels in diploid and triploid SW smolts subjected to 2 h of confinement decreased to pre–stress levels within 6 h post–confinement. Plasma lactate levels were not significantly different from pre–stress levels 48 h after confinement. As no difference exists in primary and secondary stress responses of Atlantic salmon of differing ploidy status, it is unlikely that differences in mortality rates between diploid and triploid populations under commercial conditions can be attributed to differences in their physiological responses to periods of stress lasting up to 6 h.
Description of Careproctus patagonicus sp. nov. and C. magellanicus sp. nov. (Pisces: Scorpaeniformes) from the lower slope of Drake Passage
Authors: Matallanas J. , Pequeño G.
Published: April 2005

Two new species of Liparidae are described from Drake Passage (55°32·8′ S, 65°54·3′ W). Careproctus patagonicus differs from all other congeneric species in the following combination of characters: C 9 (1+4/4), epural and parhypural unfused to single hypural; gill slit above P base; lower pectoral lobe well developed; pectoral girdle with one ventral radial (0+0+0+1) with a central foramen; da 2·4, aAf 10·2% LS; disk 41·5% HL; some crater‐like pits on posterior half of body; head and anterior part of body white. Careproctus magellanicus has the following diagnostic characters: A 46; P 24, well‐developed lower pectoral lobe; scattered crater‐like spots and some thumb‐tack prickles on body; one suprabranchial pore; basal plate of the pectoral girdle with two fenestrae; four radials (3+1), the first with a ventral notch; HL 17·1, preD 18·5% LS. The structure of the endochondral pectoral girdle of both species is commented.
Genetic structure of Lake Magadi tilapia populations
Authors: Wilson P. J. , Wood C. M. , Maina J. N. , White B. N.
Published: April 2005

The control region of the mitochondrial DNA haplotype frequencies were significantly different among the two separate lagoon populations of Oreochromis alcalicus grahami in Lake Magadi and of O. a. alcalicus from lake Natron, and DNA fingerprint similarity indices were significantly higher for intra‐population comparisons of the two Magadi lagoon populations and the Lake Natron population than the inter‐population similarity indices among these populations. A modified Fst measure indicated population sub‐division and the phylogeographic partitioning of the VNTR fragments observed were unique to specific populations further indicating substantial genetic differentiation. The lagoon populations within Lake Magadi demonstrated the same degree of genetic differentiation as either of these populations did to the outgroup (the Lake Natron population). There appears to be limited gene flow between Lake Magadi tilapia populations and this population structure has important implications for protecting locally adapted populations within this unique ecosystem.
Comparative ultrastructural studies of the zona radiata of marine fish eggs in three genera in Perciformes
Authors: Li Y. H. , Wu C. C. , Yang J. S.
Published: April 2005

The eggs of Mugil cephalus were significantly larger than those of Epinephelus malabaricus, and E. coioides, while those of Sciaenops ocellatus were intermediate between E. coioides and M. cephalus. The distribution density of pores in the egg envelope of S. ocellatus was significantly different from that of E. malabaricus and E. coioides. The micropyle diameters were significantly different in the four species. The ultrastructure of the zona radiata surface, the distribution density of pores and the size of eggs were also useful characters for distinguishing among the four species, but the ultrastructural features of the micropyles were the most important of all for egg identification.
Pattern of hyperphagia in immature three‐spined sticklebacks after short‐term food deprivation
Authors: Ali M. , Wootton R. J.
Published: April 2005

Juvenile three‐spined sticklebacks Gasterosteus aculeatus were fed live enchytraeid worms, and mean daily ad libitum consumption in the absence of periods of deprivation was 11·7% of initial body weight. Then, six groups of five replicate fish were subjected to 1, 3 and 6 days without food. Each period of deprivation was followed by 1 day of ad libitum feeding. The sequential order of deprivations differed between groups. Over the sequence of deprivations and re‐feedings, mean cumulative consumption did not differ between groups. Mean daily consumption was 19·8% of initial body weight after a 1‐day deprivation, 22·3% after 3 days and 19·5% after 6 days. However, consumption in the 24 h after a given length of deprivation also depended on the prior history of deprivation. Specific growth rate over the experiment did not differ between groups. The results provide evidence for an effective regulation of appetite in growing sticklebacks.
Contrasting seasonal modulation of the stress response in male and female rainbow trout
Authors: Pottinger T. G. , Carrucj T. R.
Published: April 2005

Between June and September the magnitude of the plasma cortisol response of maturing male and female rainbow trout to confinement was indistinguishable. A progressive increase in confinement‐induced cortisol levels in both sexes occurred during May to September, associated with the seasonal rise in water temperature. Between September and January a reduction of >50% in the magnitude of the cortisol response to confinement in male fish (but no decline in females) coincided with declining water temperature and significant increases in plasma 11‐ketotestosterone and elevated plasma testosterone levels. Plasma oestradiol‐17β levels were significantly greater in females than males throughout the study period and this difference was maximal between September and January. However, plasma testosterone was also elevated in females during this period and levels overall were higher than those in male fish. Previous studies have shown oestradiol‐17β and testosterone to have diametrically opposed effects on stress responsiveness in trout, with the former enhancing, and the latter suppressing, the cortisol response to a stressor. The relative roles of androgens, estrogen and water temperature in modulating the stress responsiveness of rainbow trout are discussed.
Feeding chronology of Atlantic salmon parr in subarctic rivers: consistency of nocturnal feeding
Authors: Amundsen P.‐A. , Gabler H.‐M. , Herfindal T. , Riise L. S.
Published: April 2005

During the ice‐free season in three subarctic rivers in northern Norway and Finland, Atlantic salmon parrSalmo salarexhibited significant diel fluctuations in stomach content weights in August and September, the largest weights being recorded consistently at 0300 hours. Accordingly, the feeding rate of the parr was highest during the night and lowest in daytime, whereas during the other periods of the ice‐free season, no pronounced diel fluctuations in food intake occurred. The consistent nocturnal feeding periodicity in early autumn in subarctic rivers may be associated with benthic feeding and an increased availability of benthic prey at night.
Does socially induced stress in rainbow trout cause chloride cell proliferation?
Authors: Sloman K. A. , Gilmour K. M. , Metcalfe N. B. , Taylor A. C.
Published: April 2005

At the end of a 2‐week confinement period, subordinate rainbow trout Oncorhynchus mykiss had significantly higher circulating concentrations of plasma cortisol than did the dominant fish with which they were paired. Physiological effects linked to elevated plasma cortisol concentrations in subordinate fish included loss of weight and a lowering of condition factor. However, there were no significant differences in gill epithelium chloride cell numbers or blood plasma ion concentrations between dominant and subordinate fish. It is concluded that elevated plasma cortisol concentrations elicited by the social stressors of the present study did not cause proliferation of chloride cells.
Food of introduced pumpkinseed sunfish: ontogenetic diet shift and seasonal variation
Authors: García‐Berthou E. , Moreno‐Amich R.
Published: April 2005

The pumpkinseed sunfish Lepomis gibbosus introduced into Lake Banyoles (Spain) were predominantly littoral but there was a tendency of large fish to use deeper zones. Their diet was dominated by littoral macrobenthos, particularly amphipods (Echinogammarus sp.). There was ontogenetic variation in the diet, with small young‐of‐the‐year (LF<4 cm) feeding on several littoral microcrustaceans, especially the cladoceran Ceriodaphnia reticulata, whereas larger fish shifted to a freshwater shrimp (Atyaephyra desmaresti), snails and damselfly larvae. Seasonal variation in diet was linked to resource availability, with consumption of fish eggs and plant debris in spring and summer. In autumn, pumpkinseeds were partially zooplanktivores, preying on the cladoceran Daphnia longispina. The diet of pumpkinseeds in Lake Banyoles and other Iberian populations shows less molluscivory than North American populations. The potential ecological impact of this successful exotic species involves mainly predation on fish eggs and molluscs.
The stability of standard metabolic rate during a period of food deprivation in juvenile Atlantic salmon
Authors: O'Connor K.I. , Taylor A.C. , Metcalfe N.B.
Published: April 2005

Among juvenile Atlantic salmon Salmo salar either being fed ad libitum throughout a 3 month experiment or deprived of food in the middle month, food deprivation led to a decrease in SMR, which increased again once food was supplied ad libitum again. While the rank order of SMR among fish fed throughout remained relatively stable, that within the deprived group was inconsistent, suggesting that individual fish vary in their ability to reduce metabolic costs when food availability is low.
Shifts in drag and swimming potential during grayling ontogenesis: relations with habitat use
Authors: Sagnes P. , Champagne J‐Y. , Morel R.
Published: April 2005

The drag coefficient (Cd) of grayling Thymallus thymallus was dependent on body surface conditions and rigidity. At comparable flow conditions, Cd values of a fish preserved in formalin (high body rigidity) were 15–30% lower than those obtained on a freshly‐killed fish (medium rigidity); the presence of skin mucus on fish could reduce Cd by 10%. The hydrodynamic potential of grayling increased during ontogenesis, because Cd values decreased (except for yolk sac larvae, which had a particular morphology) and the swimming capacities (in terms of relative muscular mass) increased. Grayling morphology evolves towards hydrodynamically efficient shape at high velocities, and there is a relationship between these shifts in hydrodynamic abilities and the different habitats (in terms of current velocity) used by five morphological groups. Therefore, the concept of hydrodynamic potential (i.e. hydrodynamics of shape and swimming capacities) could be a useful tool in fish ecomorphology and predictions of habitat use.
Experimental study of young fish distribution and behaviour under combined influence of baro‐, photo‐ and thermo‐gradients
Authors: Pavlov D.S. , Sadkovskii R.V. , Kostin V.V. , Lupandin A.I.
Published: April 2005

The complex influence of baro‐, photo‐ and thermo‐gradients on distribution and behaviour of young physostomous Leuciscus leuciscus L., leaciscus idus L. and physoclistous fish Perca fluviatilis L. was investigated. 40 different combinations consisting of 4 types of photogradients, 3 types of termo gradients and 4 types of baro‐gradients were tested. All considered factors influenced the distribution of physostomous and physoclistous fish with high degree of significance. Under a multi‐factorial experiment fish behaviour and distribution are determined not only by a separately taken environmental factor but by the presence of other accompanying factors. Under different combinations of imposed factors, the reaction of fish to an individual factor and the character of the response (positive or negative) may change. Hydrostatic pressure is one of the strongest factors which influence fish distribution. The presence of its gradient may change the character of response of perch Perca fluviatilis to light (a changing of a sign of its photoreaction). Water temperature influences fish distribution more than illumination. However, the definite value of water temperature at which most fish prefer to stay may be changed depending on both the intensity of illumination and the value of hydrostatic pressure.
Non‐invasive recording of heart rate and ventilation rate in rainbow trout during rest and swimming. Fish go wireless!
Authors: Altimiras J. , Larsen E.
Published: April 2005

Resting heart rates and ventilation rates in rainbow trout Oncorhynchus mykiss at 15°C are 31·8±1·8 beat min−1 and 53·1±3·7 breaths min−1, respectively. The non‐invasive recording system picked up the bioelectric potentials generated by the fish in the water and was based on an array of six silver‐silver chloride electrodes covered with agar‐gel, which provided a better signal‐to‐noise ratio than in previously described systems, and allowed the determination of heart rate and ventilation rates at different swimming speeds up to 21 s−1. In concert with the lower rates, the scope for changes in heart rate and ventilation rate during swimming was also considerably larger than in earlier studies (2·4‐ and 2·0‐fold, respectively). Two main conclusions result from this work: (i) short recovery times under 48 h after anaesthesia and surgery are unlikely to provide truly resting heart rates and ventilation rates in trout at 15°C; (ii) heart rate regulation during exercise is more important than previously thought and might account for a larger proportion of the increase in cardiac output observed in swimming trout.
Phenotypic sex differentiation of blue tilapia under constant and fluctuating thermal regimes and its adaptive and evolutionary implications
Authors: Baras E. , Prignon C. , Gohoungo G. , Méalard C.
Published: April 2005

Oreochromis aureus exposed during the first 28 days of exogenous feeding to constant 35° C, or fluctuating temperatures (day at 35° C, night at 27° C, and vice versa) showed significantly (P<0·05) faster growth, least size heterogeneity and better survival rates than siblings under constant 27° C. Constant high temperatures had a strong masculinizing effect (M: F sex ratios of 7·33–19·00: 1·00 v. 0·75–0·82: 1·00 in controls reared at 27° C). Fluctuating temperatures had less masculinizing potential but still produced sex ratios significantly skewed to the detriment of females (M: F sex ratios of 2·33–11·50: 1·00). This suggests that ambient temperature may have represented a sufficient environmental pressure for the selection of thermolabile sex‐determinism in this species, and presumably in other Oreochromis spp. The evolutionary advantage of thermosensitivity in Oreochromis spp. is discussed, considering a framework where individual advantages oppose, to some degree, to the population or species interest.
Maternal transfer of cadmium tolerance in larvalOreochromis mossambicus
Authors: Lin H. C. , Hsu S.C , Hwang P.P.
Published: April 2005

Exposing female tilapia to Cd did not affect reproduction and egg quality, nor the survival of their offspring. TheLT50of Cd‐exposed larvae (within 24 h post hatching) from Cd‐treated femaleOreochromis mossambicus(mean ±S.E.=10·9±0·5 days,n=4) was greater than that of Cd‐exposed larvae from control females (6·9± 1·2 days,n=4). A substantial amount of metallothionein mRNA (MT mRNA) was found in both oocytes and newly hatched larvae from Cd‐treated females, but MT mRNA levels were low in newly fertilized eggs. The amount of MT mRNA was very low in all these stages in the control group. Cadmium could not be detected at any stage for either control or Cd‐treated group, and metallothionein protein levels were also very low in both groups. The early appearance of MT mRNA in oocytes and newly hatched larvae from Cd‐treated females may result in early translation after hatching and explain their tolerance to Cd.
Distribution pattern of river blennies in the Júcar River basin (eastern Spain)
Authors: Hernández R. , Lacomba R. T. , Uviñtas Y. N. , Oltra R.
Published: April 2005

Salaria fluviatilis in the Júcar river basin was found only in the Júcar River itself, the tributaries Cabriel and Escalona, and the irrigation channel Acequia Real. Blenny density varied from 0·2 to 3·1 ind m−2. Sites with blennies had significantly lower coliform counts than those without blennies.
Methods for assessing social status in Arctic charr
Authors: Bailey J. , Alanäuräu A. , Bräunnäus E.
Published: April 2005

The aggression index is a more reliable method for assessing the social status of Arctic charr Salvelinus alpinus held in small groups, than is food intake or position relative to a defensible food resource. However, care must be taken when assigning rank, as all three of these commonly used methods can result in different social ranks for an individual fish.
Empirical relationships to estimate asymptotic length, length at first maturity and length at maximum yield per recruit in fishes, with a simple method to evaluate length frequency data
Authors: Froese R. , Binohlan C.
Published: April 2005

Empirical relationships are presented to estimate in fishes, asymptotic length (L∞) from maximum observed length (Lmax), length at first maturity (Lm) from L∞, life span (tmax) from age at first maturity (tm), and length at maximum possible yield per recruit (Lopt) from L∞ and from Lm, respectively. The age at Lopt is found to be a good indicator of generation time in fishes. A spreadsheet containing the various equations can be downloaded from the Internet at http://www.fishbase.org/download as popdynJFB.zip. A simple method is presented for evaluation of length–frequency data in their relationship to L∞, Lm and Lopt. This can be used to evaluate the quality of the length–frequency sample and the status of the population. Three examples demonstrate the usefulness of this method. 2000 The Fisheries Society of the British Isles
Branchial arches of suspension–feeding Oreochromis esculentus: sieve or sticky filter?
Authors: Goodrich J. S. , Sanderson S. L. , Batjakas I. E. , Kaufman L. S.
Published: April 2005

Only 4% of 600 particles slid on or adhered to buccopharyngeal surfaces of Oreochromis esculentus. Only a minute quantity of mucus was visible during feeding (0·6% of 68 224 video frames; 30 frames s–1), and very few particles were retained in this mucus. Filtration by mucus entrapment on the branchial arches is rejected as a mechanism of particle retention in this species. Since particles contacted the branchial arches infrequently, and the inter–raker spaces are too large to retain particles less than approximately 50 μm, sieving by gill rakers as a particle retention mechanism is rejected also. Unlike the suspension–feeding congener O. niloticus, O. esculentus does not use branchial arches to retain food particles by sieving or by mucus entrapment.
Effect of fluctuating flow and temperature on cover type selection and behaviour by juvenile brown trout in artificial flumes
Authors: Vehanen T. , Bjerke P. L. , Heggenes J. , Huusko A. , Mäki–Petäys A.
Published: April 2005

Brown troutSalmo truttain a flume used cover more often and were more aggregated at low water temperatures in winter compared with summer. Cover combinations providing the most cover (overhead, visual and velocity cover) were preferred in winter whereas velocity refuges were preferred in late summer; and brown trout rarely used any of these cover structures in early summer. Flow affected cover use especially in winter, when most of the trout moved to shelters during the first high flow period. Movements by brown trout were most frequent in early summer. The much higher aggression rate in summer compared with winter decreased during the first period of high flow in both summer experiments. The results indicate seasonal changes in cover habitat and cover type preferences suggesting that habitat complexity is important, and availability of cover is particularly important during different seasons and fluctuating flow.
Ontogenetic changes in the diet of the herbivorous Scartichthys viridis in a rocky intertidal zone in central Chile
Authors: Muñoz A. A. , Ojeda F. P.
Published: April 2005

Scartichthys viridis maintains a herbivorous diet following recruitment to rocky intertidal areas, where it consumes almost exclusively macroalgae. The sheet–like green macroalgae Ulva and Enteromorpha were the main items consumed by individuals <130 mm LT. The tough branching red macroalga Gelidium made the bulk of the gut contents of specimens >220 mm LT, Ulva being consumed to a much lesser extent. Further, Gelidium increased in importance in the total gut contents during ontogeny. In contrast, both small (70–120 mm LT) and medium–sized (140–210 mm LT) S. viridis individuals preferred Ulva in the laboratory. It is suggested that the increasing consumption of Gelidium along the ontogeny of S. viridis results from the limited availability of Ulva in the field. Large S. viridis individuals possessed longer guts relative to their body length, in comparison with small individuals.
Differential survival of juvenile sockeye and coho salmon exposed to low dissolved oxygen during winter
Authors: Ruggerone G. T.
Published: April 2005

Juvenile sockeye salmon (43–78 mm) survived 100% for 24 h in cages in ice–covered Black Lake, Alaska at oxygen saturations >65% (9 mg l–1), but only 45% at 24% saturation (3·0–3·3 mg l–1) and none at <17% saturation (2·3 mg l–1). All juvenile coho (50–120 mm) survived 100% for 24 h down to 21% oxygen saturation (3·1 mg l–1), and all 50 coho survived 4–5 days at 23–24% saturation (3·2–3·3 mg l–1).
Accuracy, precision and quality control in age determination, including a review of the use and abuse of age validation methods
Authors: Campana S. E.
Published: April 2005

Many calcified structures produce periodic growth increments useful for age determination at the annual or daily scale. However, age determination is invariably accompanied by various sources of error, some of which can have a serious effect on age‐structured calculations. This review highlights the best available methods for insuring ageing accuracy and quantifying ageing precision, whether in support of large‐scale production ageing or a small‐scale research project. Included in this review is a critical overview of methods used to initiate and pursue an accurate and controlled ageing program, including (but not limited to) validation of an ageing method. The distinction between validation of absolute age and increment periodicity is emphasized, as is the importance of determining the age of first increment formation. Based on an analysis of 372 papers reporting age validation since 1983, considerable progress has been made in age validation efforts in recent years. Nevertheless, several of the age validation methods which have been used routinely are of dubious value, particularly marginal increment analysis. The two major measures of precision, average percent error and coefficient of variation, are shown to be functionally equivalent, and a conversion factor relating the two is presented. Through use of quality control monitoring, ageing errors are readily detected and quantified; reference collections are the key to both quality control and reduction of costs. Although some level of random ageing error is unavoidable, such error can often be corrected after the fact using statistical (‘digital sharpening)’ methods.
Evidence for selective angling of introduced trout and their hybrids in a stocked brown trout population
Authors: Mezzera M. , Largiadèr C. R.
Published: April 2005

Comparisons of the genetic composition of brown trout Salmo trutta captured by anglers and by electrofishing based on three diagnostic microsatellite loci provided strong evidence that angling is selective in a stocked brown trout population. At two sites, anglers caught significantly younger trout and proportionally more introduced hatchery trout and hybrids than were observed in electrofishing surveys. Selective angling, in combination with a small legal catch size, may have considerably eliminated introduced trout and hybrids before spawning at the study sites, and thus may have reduced the introgression of alien genes into the local gene pool. Angling can be an important factor influencing the genetic structure of fish populations and should be taken into account in studies of introgressive hybridization in stocked fish populations and their management. In this study, demographic consequences of stocking were not assessed. Thus, even though the genetic consequences of stocking may be minimal or largely reversible through angling, resource competition between native and introduced trout, until they reach legal catch size, is expected to have a negative effect on the productivity of the indigenous trout population.
Distribution of migratory fishes and shrimps along multivariate gradients in tropical island streams
Authors: Fièvet E. , Dolédec S. , Lim P.
Published: April 2005

Among the 16 species of fishes and shrimps studied at 51 sites along several small streams at Basse Terre, Guadeloupe, Lesser Antilles, more than 60% showed a spatial distribution significantly influenced by environmental conditions. These included altitude, basin size, terrestrial vegetation and land use. However, the range of the species habitat was generally high, except for three species limited to the downstream stretches (two fishes and one shrimp). The habitat characteristics of fish and shrimp species tended to differ, but the difference was not significant (P<0·05). On the contrary, the habitat characteristics of amphidromous and catadromous species clearly differed, with a lower occurrence at the most elevated sites of catadromous species than amphidromous species.
Experimental vaccination of rainbow trout against Loma salmonae using a live low‐virulence variant of L. salmonae
Authors: Sánchez J. G. , Speare D. J. , Markham R. J. F. , Jones S. R. M.
Published: April 2005

Prior exposure of rainbow trout Oncorhynchus mykiss juveniles to the low‐virulence variant of Loma salmonae, L. salmonae SV, spores resulted in a xenoma intensity in the gill filaments fourteen times lower (0·044 v. 0·641 xenomas per filament; P=0·0001) than that observed in the naive controls, challenged with L. salmonae spores, as determined morphometrically by in situ hybridization at the peak of the disease (between 4 and 6 weeks post exposure). The marked degree of reduction in numbers of xenomas that formed after challenge suggests that use of the low‐virulence variants should be further considered as a means to protect fish in regions where the parasite is endemic, to protect them during grow out periods.
Gonadal investment of young males in two blenniid fishes with alternative mating tactics
Authors: Oliveira R. F. , Gonçalves E. J. , Santos R. S.
Published: April 2005

The males of two blenniid species which exhibited alternative life history tactics and matured in their first year of life varied in size distribution within the age class and in behaviour. Salaria pavo were the smaller fish of the age class and behaved as sneaker males whereas Parablennius sanguinolentus parvicornis were the larger fish and behaved as satellites.
The relationship between stomach contents and maturity state for major northwest Atlantic fishes: new paradigms?
Authors: Link J. S. , Burnett J.
Published: April 2005

Iteroparous species examined from the northwest Atlantic demonstrated distinct relationships between feeding and reproduction. Two species showed an increase in feeding during the developing, ripe and running stages of reproduction, indicative of the ramper pattern. Four species showed an increase in feeding after spawning in the spent or resting stage of reproduction, indicative of the rester pattern. Two species exhibited no distinct pattern. Evidence from other species confirms these major patterns. This information may be useful to determine the effectiveness of different management measures, particularly in relation to feeding or spawning aggregations. There are two major feeding‐reproductive patterns for fishes along a continuum of possibilities.
Mass‐length relationship of Mediterranean barbel as an indicator of environmental status in South‐west European stream ecosystems
Authors: Vila‐Gispert A. , Moreno‐Amich R.
Published: April 2005

Analysis of mass‐length relationships of 10 populations of Mediterranean barbel from three basins with different environmental conditions showed that there were significant differences (ANCOVA, P<0∣05) in relationships between sampling sites, which could imply differences in environmental conditions. Oxygen concentration and riparian cover were found to be the environmental variables that accounted for most variation (83%) in parameter a of the mass‐length relationship between populations. Thus, mass‐length relationships of barbels can be used to assess environmental conditions in southwestern European streams.
Female choice for good genes and sex‐biased broods in guppies
Authors: Watt P. J. , Shohet A. J. , Renshaw K.
Published: April 2005

In a population of guppies Poecilia reticulata females were found to prefer large males and the offspring of these males had a higher survival rate than those sired by smaller males, suggesting that females were selecting their mates on the basis of their good genes. The possibility that females differentially invested in male or female offspring depending on the size or attractiveness of their mate was also investigated, but no relationship was found between a male's attractiveness or body size and the sex ratio of the offspring he sired. However, a strong female‐biased sex ratio was detected in the broods and the proportion of males produced decreased with the amount of time that a female was confined with a male. The possible reasons for this are discussed.