bluuebunny/crossref_metadata_2025 huggingface dataset:
The first record of a biparental mouthbrooding catfish
Authors: Ochi H. , Rossiter A. , Yanagisawa Y.
Published: April 2005

In Lake Tanganyika the bagrid catfishPhyllonemus typusis a biparental mouthbrooder, the first such record among catfishes. Eggs and yolk‐sac larvae are mouthbrooded by either or both parents, and following yolk‐sac absorption, young are released temporarily from the mouth to feed beneath rocks which being guarded by both parents.
Freshwater and estuarine fishes of the Russian Arctic coast (the Swedish–Russian Expedition ‘Tundra Ecology—94‘)
Authors: Novikov G. G. , Politov D. V. , Makhorov A. A. , Malinina T. V. , Afanasiev K. I. , Fernholm B.
Published: April 2005

The distribution of estuarine and freshwater fish species caught during the Swedish‐Russian Expedition' Tundra Ecology–94’is presented. Thirteen sites along the Russian part of the Arctic Sea coast were sampled and a total of 21 fish species of the families Salmonidae, Coregonidae, Thymallidae, Osmeridae, Cyprinidae, Catostomidae, Balitoridae, Gadidae, Gasterosteidae, Percidae, Cottidae, Pleuronectidae were recorded. Some records were new to particular basins.
Sequence diversity of Mhc genes in lake whitefish
Authors: Binz T. , Largiader C. , Müller R. , Wedekind C.
Published: April 2005

The sequence variation of three exons of the major histocompatibility complex (Mhc) was examined in a lake whitefish Coregonus sp., population from the Swiss lake of Hallwil. DNA sequences from the Mhc class I A1, A2 and class II B1 exons, corresponding to the α1, α2 and β1 domains of the Mhc glycoproteins, were obtained by the polymerase chain reaction followed by cloning and sequencing. The numbers of variable sequences detected for each exon were 15 (A1), 11 (A2) and 20 (B1). Levels of nucleotide similarity ranged from 82 to 99% for the A1 exon, 58–96% for the A2 and 88–99% for the B1 exon. At the A1 and B1 exons, the nonsynonymous substitution rates (dn) exceeded synonymous substitution rates (ds) greatly within the peptide binding regions, indicating the effect of balancing selection. Sequence diversity at the A2 exon did not seem to be maintained by balancing selection (ds > dn). Phylogenetic comparison of whitefish Mhc sequences with sequences from other salmonid species and more distantly related teleosts indicated shared ancestral (trans‐species) polymorphism.
A revision of the akysid catfish genusAcrochordonichthysBleeker
Authors: Ng H. H. , Ng† P. K. L.
Published: April 2005

The taxonomy of the South‐east Asian catfish genusAcrochordonichthys(Akysidae) is revised.The shapes of the snout, humeral process and adipose fins are diagnostic species characters. Only four out of 11 species and one sub‐species described prior to this study are considered valid, namelyA. rugosus(Bleeker, 1847),A. ischnosomaBleeker, 1858,A. chamaeleon(Vaillant, 1902), andA. pachydermaVaillant, 1902. An additional five new species (A. guttatus, A. septentrionalis, A. mahakamensis, A. strigosusandA. falcifer) are described.
Cellular expression of the pepsinogen and gastric proton pump genes in the stomach of winter flounder as determined by in situ hybridization
Authors: Gawlicka A. , Leggiadro C. T. , Gallant J. W. , Douglas S. E.
Published: April 2005

The sites of pepsinogen synthesis and hydrochloric acid secretion were localized in the glandular stomach mucosa of winter flounder using in situ hybridization with gastric‐specific, biotinylated antisense RNA probes for three genes: pepsinogen IIa, pepsinogen IIb and the a‐subunit of the proton pump (H+/K+‐ATPase). The spatial expression patterns of the pepsinogen IIa and IIb genes appeared to be the same, but they differed from that of the ‐proton pump gene. The gastric gland cells contained transcripts (mRNAs) of all three genes, whereas the mucous neck cells and surface mucous cells contained transcript of the a‐proton pump only. The expression of the pepsinogen IIa, pepsinogen IIb and α‐proton pump gene in the same gastric gland cells indicates that these cells synthesize pepsinogens and secrete hydrochloric acid simultaneously and confirms that they are of the oxynticopeptic type. The presence of the a‐proton pump mRNA in the mucous neck and surface mucous cells, shown here for the first time, indicates that these cells are capable of secreting hydrochloric acid. The physiological importance of hydrochloric acid secretion by these two cell types remains unknown.
Comparison of several techniques for mobility and activity estimates of smallmouth bass in lentic environments
Authors: Cooke S. J. , Bunt C. M. , Schreer J. F. , Wahl D. H.
Published: April 2005

Mean daily mobility estimates for smallmouth bass Micropterus dolomieu from mark‐recapture (47·5±12·5 m) were less than from conventional telemetry (77·1±10·6 m). The relationship developed in a respirometer between the activity transmitter and swimming speed (r2=0·99, P < 0·001, n=6) when applied to field activity data estimated mean daily movement at 27 408±4085 m, i.e. >100 times mark/recapture or telemetry estimates. Using these estimates in the activity parameter of a bioenergetics model resulted in different model outputs. These results highlight the potential underestimates in activity associated with using traditional mark‐recapture and locational telemetry and reaffirm that fish expend a significant portion of their activity budgets undertaking localized movements.
Use of micreosatellite markers for identification of indigenous brown trout in a geographical region heavily influenced by stocked domensticated trout
Authors: Fritzner N. G. , Hansen M. M. , Madsen S. S. , Kristiansen K.
Published: April 2005

Based on estimates of genetic differentiation between populations, assignment tests and analysis of isolation by distance, stocked populations of brown trout Salmo trutta of Funen Island, Denmark, had been genetically affected by domesticated trout, whereas the stocking of wild exogenous trout into one of the rivers had little or no impact. At the same time, there were clear indications of remaining indigenous gene pools in the Funen populations. The management implications of these findings are discussed and changes in trout release activity are recommended to avoid further mixing of trout gene pools.
Characteristics of egg and larval production in captive bluespotted gobies
Authors: Privitera L. A.
Published: April 2005

Spawning of the Hawaiian coral‐reef goby Asterropteryx semipunctata was diurnal, occurring at various times throughout the day. Mean length of eggs deposited in nests was 0·76 mm (range 0·67–0·84); mean egg width was 0·47 mm (range 0·41–0·52). Clutch size varied from 296 to 1552 eggs (mean=886±309), and was independent of standard length, total body weight, and body condition. Mean relative clutch size was 1·59 eggs mg‐1 total body weight (range 0·84–2·43). Clutches hatched 4–5 nights after being deposited in a nest. Mean notochord length of newly‐hatched larvae was 1·88 mm (range 1·60–2·04). The minimum period of time that elapsed between egg deposition and subsequent growth of a new batch of oocytes to spawning size was 5–6 days, providing a reasonable estimate of minimum spawning interval. Compared with other gobiids, tropical species tend to have shorter incubation periods, smaller eggs and smaller larvae at hatching.
Differences in temperature conditions and somatic growth rate of larval and early juvenile spring‐spawned herring from the Vistula Lagoon, Baltic Sea manifested in the otolith to fish size relationship
Authors: Fey D. P.
Published: April 2005

Larval and juvenile herring Clupea harengus collected in the Polish part of the Vistula Lagoon in May‐July 1997 had hatched between 17 April and 9 June and originated from three cohorts. The spawning season began on 1 March at 3·8° C and was completed on 3 June at 12·7° C. Mortality among larvae was high in the first 2 weeks of April, probably associated with significant temperature decrease at the beginning of the spawning season. The growth of 10–48 mm LS herring was linear, highest for larvae and juveniles from the first cohort (0·58 mm mm‐1 day‐1), slower for the second cohort (0·55 mm mm‐1 day‐1) and the slowest for the third cohort (0·45 mm mm day‐1). Temperature effects on the growth were inconclusive and potentially unfavourable feeding conditions in June might have been responsible for the relatively slow growth of third cohort larvae and juveniles.

Relationships between otolith size (perimeter, length, width, area, and weight) and fish size (LS) differed among the three cohorts, related mostly to the positive temperature effect on otolith growth, individuals growing in warmer water had larger otoliths. Although a negative growth rate effect was observed as well, it was less significant.
Differential effects of food and temperature lead to decoupling of short‐term otolith and somatic growth rates in juvenile King George whiting
Authors: Barber M. C. , Jenkins G. P.
Published: April 2005

In experiments manipulating temperature and food levels, rates of short‐term otolith growth and somatic growth of juvenile King George whiting Sillaginodes punctata became decoupled. Food levels were starvation, 100 and 1000 μg per fish per day and temperatures were 12 and 18° C. Short‐term somatic growth was influenced predominantly by food, with negligible growth at starvation and low ration, and significant growth at high food ration at both temperatures. In contrast, short‐term otolith growth was influenced predominantly by temperature, with significant otolith growth occurring for all food treatments, and elevated otolith growth occurring at the higher temperature across food treatments. The identification of such differential effects of food and temperature leading to decoupling is an important result that has significant implications for using otoliths to estimate short‐term growth.
The trade‐off between food and temperature in the habitat choice of bluegill sunfish
Authors: Wildhaber M. L.
Published: April 2005

A model is presented to describe the trade‐off between food and temperature in bluegills Lepomis macrochirus, where temperature was the primary factor used in determining the patch in which to reside.
Density‐dependent refuge use among over‐wintering wild Atlantic salmon juveniles
Authors: Armstrong J. D. , Griffiths S. W.
Published: April 2005

Sheltering behaviour of wild juvenile Atlantic salmon in an indoor stream was found to be density dependent; the proportion of fish sheltering decreased significantly with increasing population density. The mean number of fish occupying refugia was ≤1.5 fish per refuge even at very high densities (potentially 5 fish per shelter). These results suggest that shelter availability has potentially important consequences for the carrying capacity for natural populations of salmon in streams.
Artificial light and season affects vertical distribution and swimming behaviour of post‐smolt Atlantic salmon in sea cages
Authors: Oppedal F. , Juell J‐E. , Tarranger G. L. , Hansen T.
Published: April 2005

In winter, post‐smolts of Atlantic salmon Salmo salar exposed to continuous additional light of different intensities (LL) in 14 m deep sea cages maintained a constant swimming speed in circular polarized schools with maximum fish density in the warmest water layers at 11 m depth. By contrast, fish exposed to natural light only (NL) ceased swimming at dusk, ascended from the warm layer to the thermocline c. 3 m depth and were more dispersed in the whole water column during the dark phase. In early spring, fish exposed to LL of medium (LL‐MED) or high (LL‐HIGH) light intensity ascended and maximum fish density was at 5 m depth. A similar ascent was delayed to late spring in both the low intensity group (LL‐LOW) and the NL group, coinciding with a shift in maximum temperature to this depth. The advanced ascent in the LL‐HIGH and LL‐MED groups is interpreted as a light‐induced shift in a seasonal rhythm of feeding motivation. In summer, most of the fish in all four treatment groups were observed in the warm and less saline 4 m surface layer. It is suggested that the seasonal and diel changes in vertical distribution of Atlantic salmon are related inversely to feeding motivation, with preferences for maximum temperature and darkness acting as modifying factors.
Feeding and prey‐selection of wild Atlantic salmon post‐smolts
Authors: Andreassen P. M. R. , Martinussen M. B. , Hvidsten N. A. , Stefansson S. O.
Published: April 2005

The diet of post‐smolt Atlantic salmonSalmo salarcaught in the Trondheimsfjord and Frohavet in central Norway, based on stomach contents analysis, showed a gradual change during migration from the river to the estuary, fjord and coastal areas. Post‐smolts caught in the estuary had eaten intertidal gammarid amphipods, while post‐smolts caught further seawards preyed upon available marine prey such asCalanusspp., adult euphausiids and fish larvae. The frequency of adult insects was high in all post‐smolt stomachs. The gradual change in diet suggested that feeding conditions in the early marine phase were important for post‐smolt survival and growth. With the exception of the copepods, there was no overall similarity between species composition of the plankton samples and the stomach contents. Although the hypothesis that the post‐smolts are opportunistic feeders cannot be rejected, the composition of the stomach contents suggests a possible selectivity of advantageous prey.
The effect of dietary docosahexaenoic acid on schooling behaviour and brain development in larval yellowtail
Authors: Ishizaki Y. , Masuda R. , Uematsu K. , Shimizu K. , Arimoto M. , Takeuchi T.
Published: April 2005

The onset of schooling behaviour and brain growth in larval yellowtail Seriola quinqueradiata larvae fed on Artemia enriched with oleic acid (OA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) for 10 days was investigated. Larvae from the DHA groups schooled with parallel orientation while those of the EPA groups showed only aggregation. Larvae of the OA groups were dispersed. DHA and EPA groups showed significantly smaller nearest neighbour distance compared with OA groups, and DHA groups showed significantly smaller values of nearest neighbour angle compared with the other groups. The relative volume of the tectum opticus (TO) of the DHA group was significantly larger in two experiments and also the relative volume of the cerebellum (CE) of that group was significantly larger in one experiment. Dietary DHA is probably critically important for the development of the brain, particularly TO, during the larval stages, and that development of TO may be the key factor of the ontogeny of schooling behaviour.
Dietary‐morphological relationships of fishes in Liangzi Lake, China
Authors: Xie S. , Cui Y. , Li Z.
Published: April 2005

Species in Liangzi Lake were clustered into four trophic groups:Hemiramphus kurumeusandHemiculter bleekeri bleekerifed predominantly on terrestrial insects;Carassius auratus auratusandAbbottina rivularison non‐animal food;Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonison cladocerans or copepods;Culterichthys erythropteruson decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. giurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over‐dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary‐morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non‐animal food, with an increase in gut length associated with an increase in non‐animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary‐morphological relationships supported the eco‐morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co‐existing fish species.
Antibacterial factors in skin mucus of rabbitfishes
Authors: Nagashima Y. , Sendo A. , Shimakura K. , Shiomi K. , Kobayashi T. , Kimura B. , Fujii T.
Published: April 2005

Aqueous extracts from the skin mucus of two species of rabbitfishes Siganus fuscescens and S. guttatus showed antibacterial activity against gram‐negative bacteria. Stability tests and chromatographic analyses suggested that the S. fuscescens antibacterial factor is an acidic glycoprotein with a molecular mass of 400 kDa.
Allozyme differentiation of bonito in the Mediterranean Sea
Authors: Pujolar J. M. , Roldán M. I. , Pla C.
Published: April 2005

Bonito Sarda sarda samples collected in three areas from the Mediterranean Sea exhibited considerable genetic heterogeneity over all locations. This provided preliminary evidence for two different groups of bonito, one for the Ligurian and the Ionian Seas and the other for the Aegean Sea.
Thermal influences on temporal changes in plasma testosterone and oestradiol‐17β concentrations during gonadal recrudescence in female common wolffish
Authors: Tveiten H. , Johnsen H. K.
Published: April 2005

Temperature treatment during ovarian recrudescence influenced temporal changes in plasma testosterone (T) and oestradiol‐17β (E2). In fish exposed to 8 and 12° C early in the cycle the peaks of both T and E2 were delayed by 4 weeks in comparison with those of fish held at 4° C throughout the experiment. These differences were accompanied by corresponding shifts in the timing of ovulation.
First record of the Sphyraena chrysotaenia (Klunzinger, 1884) (Pisces, Sphyraenidae) from the Adriatic Sea
Authors: Pallaoro A. , Dulčić J.
Published: April 2005

One specimen of the obtuse barracuda Sphyraena chrysotaenia is recorded for the first time from the Adriatic Sea.
Social learning and life skills training for hatchery reared fish
Authors: Brown C. , Laland K.
Published: April 2005

With the stress placed on our natural resources, many fisheries increasingly rely on restocking from hatchery‐reared sources in an attempt to maintain commercially viable populations. However, the mortality rates of hatchery‐reared fishes during the period directly following release are very high. The successful development of restocking programs is consequently dependent upon production and release strategies that lead to improved migratory, antipredator and feeding behaviour in hatchery fish. While relevant individual experience prior to release might improve performance, social learning potentially provides a process whereby fish can acquire locally adaptive behaviour rapidly and efficiently. It is now well over a decade since Suboski & Templeton (1989) raised the possibility of using social learning processes to improve the post‐release survival of hatchery‐reared fishes. This period has witnessed considerable progress in the understanding of how social learning operates in fish populations. We review new methods and recent findings that suggest how social learning protocols could realistically be applied on a large scale to enhance the viability of hatchery fish prior to their release into the wild. We also suggest a practical pre‐release training protocol that may be applied at the hatchery level.
Intraspecific brood adoption in the convict cichlid with respect to fry of two colour morphs
Authors: Espmark Y. , Knudsen T.
Published: April 2005

Convict cichlid Cichlasoma nigrofasciatum adults of the melanistic morph usually accepted fry of the same colour morph provided these were of approximately the same age and size as those of the receiver pair, whereas older and considerably younger fry were rejected or eaten. Xanthoric fry were usually accepted and rejected to the same extent as fry of their own colour morph. However, in certain combinations, especially when alien fry were 3 weeks old and the adopting parents already had their own 2 week old fry, fry of their own colour morph were significantly more likely to be adopted.
An examination of the post‐planting success of hatchery brook charr possessing different mitochondrial DNA haplotypes
Authors: Ashford B. D. , Danzmann R. G.
Published: April 2005

Previous mtDNA and allozyme studies of brook charr Salvelinus fontinalis from northern Ontario lakes that had been extensively stocked with a government hatchery strain, yielded results that were incongruous with a neutral theory of selection in the mtDNA genome. A single haplotype (haplotype 1) predominated in all the fish sampled from these lakes, which is consistent with the observed distribution of this haplotype in northern portions of the species range. However, haplotype 1 does not occur in a high frequency within the hatchery strain. In a direct survivorship experiment, of 1500 fish stocked into an Ontario lake in the spring of 1994 containing a native population of brook charr, no significant differences between stocking and recapture mtDNA distributions were observed in the summer of 1994. However, a survey of young of the year in the following spring did not reveal the presence of any ‘private’ hatchery haplotypes. Significant differences in the distribution of mtDNA haplotypes were observed in two stocked lakes compared to those in the putative source hatchery strain. Haplotype 1 predominated in both these stocked lakes, suggesting that fish with this haplotype possessed increased survivorship.
Seasonal variation in density of juvenile Atlantic salmon in fluvial shoreline habitats of a large subarctic river
Authors: Niemelä E. , Julkunen M. , Erkinaro J. , Mäukinen T. S.
Published: April 2005

The densities of Atlantic salmon fry (0+ years) and parr (1+ years and older) in shoreline habitats of the large River Teno watercourse and its tributary, the River Utsjoki generally fluctuated considerably, showing an increase from early summer towards late August and a subsequent decline towards autumn. The seasonal pattern of variation in density was more distinct for parr than for fry. In the period between late July and early September, parr density followed a sinusoidal curve, being highest in late August and lowest in early August and in September. Fry density had a weaker seasonal profile than parr, being highest in late August and in early September. Frequency distributions of the parr age groups (1+, 2+ and 3+ years) were mainly independent of the sampling month.
Microsatellite data reveals weak population substructuring in Copadichromis sp.‘virginalis kajose’, a demersal cichlid from Lake Malawi, Africa
Authors: Taylor M. I. , Verheyen E.
Published: April 2005

Small but significant differences were found in allele frequencies among five populations (overall FST estimate (θ)=0·004, P=0·006; overall RST estimate (RHO)=0·019, P<0·00001) of the demersal cichlid Copadichromis sp.‘virginalis kajose’, collected from five locations in Lake Malawi. Pairwise FST estimates revealed significant differences between the most southerly population (Cape Maclear), and the three most northerly populations (Mbamba Bay, Metangula and Chilola). Pairwise RST estimates also revealed significant differences between some populations, but no geographical pattern was discernible. There was no evidence of isolation by distance using either the shortest straight‐line distance between samples, or the distance around the shoreline following a 50 m depth contour. FST estimates were considerably lower than found in previous studies on the mbuna (rock‐dwelling species), but higher than those found in a study of three pelagic cichlid species from Lake Malawi. Substructuring in C. sp.‘virginalis kajose’ appears to be on a similar scale to the Atlantic cod.
Short‐term storage of ova of common carp and tench in extenders
Authors: Linhart O. , Gela D. , Rodina M. , Gutierrez M. Rodriguez
Published: April 2005

In a study of the effect of short‐term storage on the hatching rate of common carp Cyprinus carpio and tench Tinca tinca ova in vitro in various extenders at 21° C under aerobic conditions, the best extender for 30 min storage for common carp appeared to be Dettlaff 1. This gave the same hatching rate as controls without extender (55%v. 56%). For 60 min storage of ova, the best extenders were Dettlaff 2 (24% hatching rate) and Dettlaff 3 (30%), but hatching was significantly lower than in the control (58%). In carp ovarian artificial fluid (CAF) extender, the hatching rate of common carp ova was also high after 10 min, but decreased to 12% after 30 min. In tench, the hatching rate of ova increased after 10 min storage in Dettlaff 5 extender (44%) compared to the control (41%) without extender. However, it was significantly lower after storage in Dettlaff 1, 2, 3, 4, 5 and CAF extenders for 20, 30 and 60 min, compared to controls. Malformations (10–50%) were observed in the tench second control groups without extender after 10, 20 and 30 min storage of ova.
The relationship between otolith accretion and resting metabolic rate in juvenile Atlantic salmon during a change in temperature
Authors: Wright P.J. , Fallon‐Cousins P. , Armstrong J. D.
Published: April 2005

This study confirmed earlier evidence for a correlation between otolith increment width and resting metabolic rate in the absence of somatic growth in Atlantic salmon parr. However, increment width responded more conservatively to a change in temperature than did resting metabolic rate. Consequently, the study demonstrated that although increment width varied with temperature the process governing accretion rate was not simply related to resting metabolic rate.
Flexible modes of anadromy in Baltic sea trout: making the most of marginal spawning streams
Authors: Limburg K. E. , Landergren P. , Westin L. , Elfman M. , Kristiansson P.
Published: April 2005

From examination of the ratios of strontium to calcium laid down as a lifetime record in the otoliths of sea troutSalmo truttafrom Gotland, Baltic Sea, it was found that: (1) the shortest stream was used mostly by precociously emigrant or coastally hatched spawners; (2) longer streams had more fish that underwent normal smoltification; (3) sea‐caught fish were predominantly coastally hatched (presumably near stream mouths). Furthermore, some otoliths showed no evidence of a freshwater history at all, raising the possibility of a contingent of the coastal population that does not depend on riverine spawning. The results emphasize the importance of the coastal zone as natal and early life habitat for sea trout in the Baltic, particularly with respect to a potential change to a warmer climate which may exacerbate conditions within small, ephemeral trout streams.
Differential responses of male and female red swordtails to chemical alarm cues
Authors: Mirza R. S. , Scott J. J. , Chivers D. P.
Published: April 2005

Male and female red swordtails Xiphophorus helleri exposed in the laboratory to swordtail skin extract, fathead minnow Pimephales promelas skin extract and distilled water, significantly decreased activity in response to conspecific skin extract compared to minnow skin extract or distilled water. Moreover, males and females responded differentially to conspecific skin extract. Males tended to occupy the top compartment of the tank, whereas females tended to occupy the bottom compartment and seek shelter more. In a second experiment swordtails reduced activity significantly more in response to swordtail skin extract compared to closely related guppy Poecilia reticulata skin extract, minnow skin extract or distilled water. Swordtails also reduced activity significantly more to guppy skin extract compared to minnow skin and distilled water. However, males and females did not respond differentially to guppy skin extract. This suggests that chemical alarm cues are partially conserved within the Poeciliidae, but the level of response is of lower intensity to heterospecific skin extracts.
Evidence that growth hormone‐induced elevation in routine metabolism of juvenile Atlantic salmon is a result of increased spontaneous activity
Authors: Herbert N. A. , Armstrong J.D. , Björnsson B. Th.
Published: April 2005

Growth hormone (GH) significantly increased the growth in mass and length of Atlantic salmon parr. It also significantly increased routine oxygen consumption (MO2). This change in routine MO2 could be attributed to an increase in activity, but not resting MO2. Any elevation in resting MO2 due to GH treatment is much lower than previously suggested.
Ecology of the introduced snapper Lutjanus kasmiva (Forsskal) in the reef fish assemblage of a Hawaiian bay
Authors: Friedlander M. , Parrish J. D. , DeFelice R. C.
Published: April 2005

Since its first introduction in 1955, the snapper Lutjanus kasmira (taape) has developed large populations in shallow coastal waters of Hawaii. Visual abundance estimates and trap catches of taape were different between the main habitat types of the reef. Overall, taape was the second most abundant species by numbers and biomass over a hard substratum and was patchily distributed, even within habitat type. The largest individuals occurred singly or in small groups on shallow reef slopes; on the deep slopes and in spur‐and‐groove habitat, taape occurred in larger groups of smaller sized fish. Catches in fish traps showed a negative relationship with the complexity of the adjacent natural substratum, suggesting that traps are more productive where they offer additional cover in areas with less natural cover. In all areas in which traps were used, from fringing reef to open sand, the catch was dominated by taape. Tagging confirmed the theory that taape tend to maintain a limited range over long periods. Tagging results also indicated occasional long‐range movements among major habitats and provided data confirming patterns of movement between reef habitat by day and sand habitat by night. Taape collected over open sand substratum by trap and by hook‐and‐line were smaller than those collected by the same means at the reef. Observations and collections suggested an ontogenetic trend in habitat use by taape from initial settlement in fringe areas toward ultimate residence on the main reef. Other common fish species in the reef assemblages were tested for statistical associations with taape. Although several positive species associations were found, multivariate analysis did not reveal patterns that indicated strong ecological relationships.
Static habitat partitioning and dynamic selection by sympatric young Atlantic salmon and brown trout in south‐west England streams
Authors: Heggenes J. , Saltveit S. J. , Bird D. , Grew R.
Published: April 2005

Direct underwater observation of micro‐habitat use by 1838 young Atlantic salmon Salmo salar [mean LT 7·9 ± 3.1(s.d.) cm, range 3·19] and 1227 brown trout Salmo trutta (LT 10·9 ± 5·0 cm, range 3·56) showed both species were selective in habitat use, with differences between species and fish size. Atlantic salmon and brown trout selected relatively narrow ranges for the two micro‐habitat variables snout water velocity and height above bottom, but with differences between size‐classes. The smaller fishes <7 cm held positions in slower water closer to the bottom. On a larger scale, the Atlantic salmon more often used shallower stream areas, compared with brown trout. The larger parr preferred the deeper stream areas. Atlantic salmon used higher and slightly more variable mean water velocities than brown trout. Substrata used by the two species were similar. Finer substrata, although variable, were selected at the snout position, and differences were pronounced between size‐classes. On a meso‐habitat scale, brown trout were more frequently observed in slow pool‐glide habitats, while young Atlantic salmon favoured the faster high‐gradient meso‐habitats. Small juveniles <7 cm of both species were observed most frequently in riffle‐chute habitats. Atlantic salmon and brown trout segregated with respect to use of habitat, but considerable niche overlap between species indicated competitive interactions. In particular, for small fishes <7 cm of the two species, there was almost complete niche overlap for use of water depth, while they segregated with respect to water velocity. Habitat suitability indices developed for both species for mean water velocity and water depth, tended to have their optimum at lower values compared with previous studies in larger streams, with Atlantic salmon parr in the small streams occupying the same habitat as favoured by brown trout in larger streams. The data indicate both species may be flexible in their habitat selection depending on habitat availability. Species‐specific habitat overlap between streams may be complete. However, between‐species habitat partitioning remains similar.
Biological control of the fish louse in a rainbow trout fishery
Authors: Gault N. F. S. , Kllpatrick D. J. , Stewart M. T.
Published: April 2005

Novel egg‐laying boards were found to be effective in the biological control of the freshwater fish louse Argulus foliaceus in a 12·9 ha rainbow trout Oncorhynchus mykiss fishery which had a high prevalence and intensity of infection of juvenile parasites in the early spring of 1999. Approximately 228 000 egg clutches were harvested during an extensive 14 week period of egg laying which peaked in June 1999. In contrast, only 1566 clutches were harvested in 2000, when egg laying activity showed a bi‐modal distribution, peaking in May and again in July and August. Egg laying activity decreased 145‐fold compared to 1999. Argulus foliaceus prevalence and mean intensity also decreased nine‐fold and six‐fold, respectively. The ratio of female to male A. foliaceus on rainbow trout in consecutive years was 2·9: 1 and 2·1: 1. Estimates of the size of the female A. foliaceus population based on egg‐laying activity in 1999 exceeded that derived from measurements of prevalence and intensity of infection, whereas in 2000, this was more in balance. A minimum temperature of 10° C was identified for egg laying, which occurred continuously from May to October in a broadly synchronous manner. This produced almost two generations each year, with juveniles, adults and eggs undergoing anabiosis during winter.
Diet of Atlantic cod in the southern Gulf of St Lawrence as an index of ecosystem change, 1959–2000
Authors: Hanson J. M. , Chouinard G. A.
Published: April 2005

Major temporal changes in the importance of euphausiids and Atlantic herring Clupea harengus in the diet of Atlantic cod Gadus morhua, 10–75 cm LF, occurred in shallow waters (<100 m depths) of the southern Gulf of St Lawrence between 1959 and 2000. Euphausiids represented 6–70% of prey mass for Atlantic cod 31–60 cm LF from 1959 to 1987 but only trace amounts were detected in stomachs collected from 1990 to 2000. Mysids and gammarid amphipods (for Atlantic cod ≤45 cm LF), and Atlantic herring (for Atlantic cod >45 cm LF) largely replaced euphausiids in the Atlantic cod diets from 1990 to 2000. This diet change suggested there has been a major perturbation of the food web of the southern Gulf of St Lawrence. The importance of fishes (mostly Atlantic herring) in the diet of Atlantic cod >45 cm LF increased significantly between the periods 1959–1980 and 1987–2000. Atlantic herring comprised 0–4% (mean 1.3%) of prey mass of Atlantic cod 46–60 cm LF from 1959 to 1980 and increased to 2–42% (mean 19.6%) of the diet from 1987 to 2000. Atlantic herring comprised 0–25% (mean 9.4%) of the prey mass of Atlantic cod 61–75 cm LF from 1959 to 1980 and increased to 42–81% (mean 54.2%) of prey mass from 1987 to 2000. This increased consumption of Atlantic herring was consistent with observed changes in abundance of Atlantic herring in the ecosystem between the late 1970s and 2000. The large changes in consumption of euphausiids and Atlantic herring represent highly significant changes and would need to be included in the development and interpretation of ecosystem‐based management models for this ecosystem.
The reproductive ecology and abundance of Symptevygia bonapavtii endemic to the south‐west Atlantic
Authors: Mabragaña E. , Lucifora L. O. , Massa A. M.
Published: April 2005

Logistical ogives gave an estimated LT50 value (i.e. the total length at which 50% individuals are sexually mature) of 635 mm for female and 650 mm for male Sympterygia bonapartii. Mature individuals of both sexes had significantly larger livers than immature ones and females had a significantly heavier liver than males. Clasper elongation was the first step in male maturation, followed by clasper calcification and the development of alar thorns. In mature females, the right ovary was larger than the left, which was apparently due to differences in stroma tissue. Gonadosomatic index and diameter of ovarian follicles of mature females peaked in late spring and was at a minimum from late summer and through the winter. Juvenile S. bonapartii were more abundant near estuarine areas during winter, and adults appeared in estuaries by late spring and summer. Females carrying egg‐cases were found near the shore in late spring and egg‐cases were found in benthic samples only in shallow waters suggesting that S. bonapartii deposits egg‐cases in shallow waters during late spring‐summer and that nursery areas are in outer estuarine zones. In the southern part (38°–42° S) of the study area S. bonapartii showed a strong movement to shallow waters in late spring and summer, spreading over the entire coastal area in winter. These movements are discussed in relation to water temperature and trophic interactions.
Smolting and seasonal variation in the smolt characteristics of one‐ and two‐year‐old Saimaa landlocked salmon under fish farm conditions
Authors: Kiiskinen P. , Hyvärinen H. , Piironen J.
Published: April 2005

Silvering of the skin, reduced condition factor, elevated gill Na+, K+‐ATPase activity and well‐developed capacity to regulate the osmotic and ionic balance in sea water were observed in 1 and 2 year old hatchery‐reared Saimaa landlocked salmon Salmo salar m. sebago during April‐June. Loss of hypoosmoregulatory ability and gill Na+K+‐ATPase activity was observed earlier in 2 year than 1 year old fish. Coincident with changes associated with smolting both age groups showed diminished osmoregulatory capacity in fresh water. Slow growth during May‐June may also be attributed to osmoregulatory difficulties in fresh water. These results support the suggestion that the developmental changes at smolting are seasonal and unrelated to any salinity changes and the idea of smolting as evidence of maladaptation of the fish to fresh water.
Feeding resumption, morphological changes and mortality during starvation in Japanese flounder larvae
Authors: Dou S. , Masuda R. , Tanaka M. , Tsukamoto K.
Published: April 2005

Japanese flounder Paralichthys olivaceus larvae established first feeding 3 days after hatching (DAH) at c. 17° C. Non‐fed fish reached irreversible starvation at age 5 DAH. Non‐fed fish showed similar feeding rate and feeding intensity as the fed fish when they were provided with prey before 5 DAH, after which the starved larvae did not feed even when prey became available. None of the six morphological measurements examined (total length, body height, eye height, head height, gut height and myotome height) showed significant differences between the non‐fed and fed larvae until 5 DAH. Normal development continued only in the fed group, and the non‐fed larvae showed reverse growth or body collapse after 5 DAH. Owing to the shrinkage and collapse at the top of head due to starvation, head height could be a sensitive indicator of starvation in Japanese flounder larvae. In the fed treatments, high mortality occurred from first feeding (3 DAH) to irreversible starvation (5 DAH), accounting for about two‐thirds to three‐quarters of the overall mortality (46–52%) throughout the experiments. This mortality was not prey density or larval density dependent. Mortality during the same period in the non‐fed larvae accounted for about a third of the overall mortality (100%).
Morphometric adaptations of sea bass gills to different dissolved oxygen partial pressures
Authors: Saroglia M. , Terova G. , De Stradis A. , Caputo A.
Published: April 2005

The total respiratory surface area (RSA) of sea bass Dicentrarchus labrax (initial mass 153 ± 27 g), reared in a brackish water recirculation system at 24° C for 3 months under three different oxygen partial pressures of 60, 90 and 140% saturation (87.0, 130.0 and 203.1 torr. respectively), was 351.98 (± 8.90), 264.86 (± 48.20) and 212.90 (± 57.22) mm2 g−1 body mass. RSA was negatively correlated with oxygen availability in the water. In the same experiment, no significant differences in the total length of filaments or frequency of lamellae were observed, although the total length of filaments was shorter in fish cultured under hyperoxia.
Feeding increases MyoD and PCNA expression in myogenic progenitor cells of Notothenia coviiceps
Authors: Brodeur J. C. , Peck L. S. , Johnston I. A.
Published: April 2005

Oxygen consumption and ammonia excretion of the Antarctic fish Notothenia coriiceps (18.4 cm LF) increased respectively two and fourfold above fasting levels 24 h after feeding with a single meal of shrimps (5.5 to 7.5% of body mass), and remained elevated for 120 h. In fasted fish, c‐met positive cells in the fast muscle represented 5.5% of the total number of myonuclei. The number of c‐met positive cells staining for the proliferating cell nuclear antigen was increased by 60% both 24 and 96 h after the meal, while the number of cells expressing the myogenic transcription factor, MyoD, was increased by 20% after 24 h, and by 44% after 96 h. The total numbers of c‐met positive cells and cells expressing myogenic were not significantly altered 96 h following feeding. The results are consistent with an activation of myogenic progenitor cells proliferation by feeding but suggest a relatively long cell cycle time.
Adaptive colouration of Mediterranean labrid fishes to the new habitat provided by the introduced tropical alga Caulerpa taxifolia
Authors: Arigoni S. , Francour P. , Harmelin‐Vivien M. , Zaninetti L.
Published: April 2005

Since the introduction of the invasive tropical alga Caulerpa taxifolia in the Mediterranean Sea. a new, uniformly green habitat has been available to local fish assemblages. Underwater visual censuses of three species, Symphodus ocellatus, Symphodus roissali and Coris julis, revealed a higher proportion of green morphs in the C. taxifolia meadows compared to those inhabiting their usual indigenous habitats. In a fourth species, Symphodus rostratus, the distribution of the different colour morphs did not differ between the two habitats investigated. Experiments in aquaria proved that S. ocellatus and S. roissali were homochromic species able to adapt their colouration to the environment. In contrast, no colour change was observed in S. rostratus during the experiments.
Energy density of marine pelagic fish eggs
Authors: Riis‐Vestergaard J.
Published: April 2005

Analysis of the literature on pelagic fish eggs enabled generalizations to be made of their energy densities, because the property of being buoyant in sea water appears to constrain the proximate composition of the eggs and thus to minimize interspecific variation. An energy density of 1.34 J μl−1 of total egg volume is derived for most species spawning eggs without visible oil globules. The energy density of eggs with oil globules is predicted by x (J μ11) where x is the fractional volume of the oil globule.
High mortality in introduced brown trout depressed potential gene flow to a wild population
Authors: Borgstrosm R. , Skaala Ø. , Aastveit A. H.
Published: April 2005

Hatchery reared 0+ year brown troutSalmo trutta, with 51 mm meanLT, were released in a sea trout stream in June 1991 to compare the survival of wild and introduced trout during the freshwater stage from age 0+ to 2+ years. The introduced brown trout were homozygous for a genetic marker, enabling released individuals and their offspring to be distinguished phenotypically from the local sea trout. The mean size of 0+ and 1+ year introduced parr was larger than 0+ and 1+ year wild parr, while 2+ year parr of both groups were of the same size. Half year survival rates of both introduced and wild parr increased with size up toc. 80 mm (1+ years), but then decreased, and could be described by a polynomial regression function, with the same shape for both groups. The introduced parr had, however, a significant lower survival rate than the wild parr. The number of the introduced cohort decreased from 2200 at release in 1991 toc. 20 in March 1994 (c. 1% of the original number). Between 1994 and 2000 no introduced individuals or offspring have been observed in the study area. High mortality at the parr stage and additional mortality until the spawning, give a low probability for a genetic impact on the local population as long as releases are restricted, both in time and number of fish.
Monthly variability of hydroacoustic fish stock estimates in a deep lake and its correlation to gillnet catches
Authors: Mehner T. , Schulz M.
Published: April 2005

Monthly (April to November) hydroacoustic surveys and parallel gillnet catches were used to determine vendace Coregonus albula abundance, biomass and population dynamics in a deep oligotrophic lake. By hydroacoustic surveys, recruitment of 0+ year vendace could clearly be detected. In contrast, gillnet catches resulted in low numbers of 0+ year fish, and similarly under‐represented proportions of the oldest vendace. Consequently, the correlation between hydroacoustics and gillnets with respect to fish numbers and geometric mean fish total length was high only for the age groups 1 + to 4+ years. Annual variability in hydroacoustic estimates offish abundance and biomass was high (CV=26–29%) which reflects the seasonal population dynamics of vendace.
Phenotypic plasticity in brook charr: changes in caudal fin induced by water flow
Authors: Imre I. , McLaughlin R. L. , Noakes D. L. G.
Published: April 2005

In the field, juvenile brook charr Salvelinus fontinalis inhabiting high‐velocity water were found to have larger caudal fins and more slender bodies than those inhabiting low‐velocity water. Young‐of‐the‐year S. fontinalis were reared in either a high‐ or low‐velocity treatment for 16 weeks and their morphology was measured bi‐weekly. From the second to fourth weeks of the experiment onwards, fish reared in the high‐velocity treatment had larger maximum caudal fin heights and deeper caudal peduncles than fish reared in the low‐velocity treatment. This study demonstrated that the morphological variation in caudal area exhibited by wild juvenile brook charr from microhabitats differing in water velocity could be a consequence of phenotypic plasticity in response to hydrological conditions.