bluuebunny/crossref_metadata_2025 huggingface dataset:
Life‐history patterns in a southern population of Atlantic salmon
Authors: Utrilla C. G. , Lobón‐Cerviá J.
Published: April 2005

Juvenile Atlantic salmon Salmo salar in the river Esva, Asturias, north‐west Spain, developed a bimodal growth pattern during their first growing season. Segregation between the two modes was apparent by late autumn. All fish in the upper modal group (UMG) grew throughout the year and migrated downstream in the following spring (by April) at the age of 14 months. Some lower modal group (LMG) fish (56% of the main stem, 31% and 50% of the two tributaries) silvered like smolts and apparently migrated downstream the same spring, although c. 1·5 months after UMG fish. Larger LMG fish appeared more likely than smaller ones to migrate. LMG fish did not grow in winter, but they grew fast between March and May. Maturing male parr were detected first at 5 months old in July, and they occurred initially among the faster growers, >6·8 cm long. In spite of this, length of maturing males did not change from late summer and throughout the winter, whereas that of non‐maturing UMG and LMG fishes continued to diverge from September onwards. These findings suggest that favourable conditions for growth (very early start of a long growing season) at the southern limit of the species' range may influence the life‐history pattern of this population.
Ecomorphological comparisons of sagittae in Mullus barbatus and M. surmuletus
Authors: Aguirre H. , Lombarte A.
Published: April 2005

For both Mullus barbatus and M. surmuletus, the relationship between sagitta area (O), sulcus acusticus area (S) throughout postlarval growth was characterized by their negative allometric growth. The adjusted mean S: O ratio differed between the two species. This may be associated with the difference in size and shape of the sagittae, a difference in somatic growth, and differences in food and spatial niches. The inner ear of Mullus cannot be considered as specialized and the interaction of stimuli detected by the sensory barbels and the inner ear together could be a compensatory mechanism that helps in the food search.
Stock delineation of pink snapper and tailor from Western Australia by analysis of stable isotope and strontium/calcium ratios in otolith carbonate
Authors: Edmonds J. S. , Steckis R. A. , Moran M. J. , Caputi N. , Morita M.
Published: April 2005

The 18O/16O and 13C/12C ratios in the otolith carbonate of pink snapper Pagrus auratus and tailor (bluefish) Pomatomus saltatrix, from several locations along the Western Australian coast, indicated that pink snapper stocks are location specific but that tailor stocks are less so. The hypersaline Shark Bay, on the coast of Western Australia, generated strongly characteristic isotopic signatures which serve as natural tags. Otolith carbonate from pink snapper from normal oceanic waters just north of Shark Bay showed no evidence that the fish had been in hypersaline water. Similarly, pink snapper from the hypersaline bay showed no evidence of having spent time at normal oceanic salinity. By contrast, some tailor from oceanic waters showed evidence of having spent considerable time in the bay, and some fish from the bay had oceanic signatures. This suggested that tailor were more migratory than snapper. The similarity in the distribution of the isotopic signatures (from oceanic to hypersaline) in otolith carbonate from tailor from oceanic waters north of Shark Bay (Koks Island), and from those within Shark Bay, indicated a single stock in this region (in contrast to pink snapper). Moreover, tailor from coastal south‐western Australia and from the Shark Bay area could be considered seperately for some management purposes. For pink snapper stocks from oceanic waters, oxygen isotope signatures were clearly related to water temperature although the temperature relationship was obscured for fish within Shark Bay because of the strength of the signal generated by the hypersaline water. For tailor the temperature relationship was not obvious, probably because migrations of tailor smeared the temperature effect, and the hypersaline Shark Bay waters dominated, and, possibly, at the southern extemity of the range, the freshwater in some estuaries influenced the isotopic signatures of the otolith carbonate. Strontium/calcium ratios in pink snapper otoliths also indicated a separation of stocks, but for tailor overlap of signatures again suggested migratory behaviour.
Plasma non‐esterified fatty acid profiles in wild Atlantic salmon during their freshwater migration and spawning
Authors: Booth R. K. , McKinley R. S. , Ballantyne J. S.
Published: April 2005

Total plasma non‐esterified fatty acid (NEFA) levels increased significantly in adult Atlantic salmon during the first months of their upstream migration and spawning in the Exploits River, Newfoundland, Canada. The highest levels occurred in May and were 5467±270·43 nmol ml−1 for females and 4617±334·70 nmol ml−1 for males. Significantly higher levels were maintained by females compared with males for most of the upstream migration. Between August and October, total plasma NEFA levels declined by 61% in females but only 23% in males. The decline in plasma monounsaturated and polyunsaturated fatty acid levels accounted for 74% of the loss of NEFAs in females. Specific plasma NEFAs such as 16: 0 (palmitic), 16: 1 (palmitoleic), 18: 1n9 (oleic) and 20: 5n3 (eicosapentaenoic acid) differed significantly between males and females during migration and spawning. The mean gonadosomatic index (IG) values of females in May and just prior to spawning were 0·37±0·01 and 10·25±0·32, respectively. The rapid decline in the plasma NEFA content of females coincided with the largest increase in their IG (1·85±0·02–10·25±0·32). Corresponding IG values for males were 0·34±0·01 in May and 3·33±0·78 prior to spawning. Plasma NEFA levels of spent salmon did not differ between sexes and were significantly lower than those of salmon preparing to spawn.
Testis structure and symplastic spermatid formation during spermatogenesis of pipefishes
Authors: Carcupino M. , Baldacci A. , Corso G. , Franzoi P. , Pala M. , Mazzini M.
Published: April 2005

The pipefishes Syngnathus abaster and S. acus have paired testes of atypical organization. Each testis is a hollow tube consisting of a single germinal compartment of the tubular type. During the reproductive period, the germinal epithelium consists of small spermatocysts containing spermatogonia or primary spermatocytes. Cysts of older germ cells, such as secondary spermatocytes and spermatids were never observed. Developing symplastic spermatids were found in the lumen of the tubule together with mature sperm and large droplet‐containing cells. Most of the spermatids were giant cells with four nuclei at the same developmental stage. Symplastic spermatids, which presumably form by nuclear division not followed by cytokinesis, are a stage of spermatogenesis in pipefishes.
Spawning migration of Balon's ruffe into a Danubian side branch in Austria
Authors: Siligato S.
Published: April 2005

The migrations of Gymnocephalus baloni Balon's ruffe into the side branch of the Danube at Schönbühel were restricted to the spawning season between the end of April and mid‐June. The main environmental factor correlating with the immigration is assumed to be water temperature. Water level changes influence emigration.
Activity, feeding behaviour and diet of Ogcocephalus vespertilio in southern west Atlantic
Authors: Gibran F. Z. , Castro R. M. C.
Published: April 2005

The Brazilian batfish Ogcocephalus vespertilio is a nocturnal and early morning predator on bottom invertebrates, staying stationary and hidden in rock holes, crevices or among bottom rocks during the day. While active, it searches for prey walking along the bottom with the help of its specialized paired fins, with the illicium protracted and oscillating or exploring the substrate. The prey are either snapped up from the bottom, after visual detection, or dug out with use of the mouth and rostrum. It feeds on crustaceans (hermit crabs, true crabs, shrimps, amphipods, porcelain crabs, isopods and mysid shrimps), molluscs (snails, sea slugs and clams), polychaete worms (mostly Errantia) and echinoderms (sea urchins and brittle stars).
The common dab as definitive host for the Pennellid copepods Lernaeocera branchialis and Haemobaphes cyclopterina
Authors: Begg G. S. , Bruno D. W.
Published: April 2005

Seven (0.039%) and five (0·028%) of 18 163 common dab from the east coast of Scotland were definitive hosts to Lernaeocera branchialis and to Haemobaphes cyclopterina, respectively. Both represent new host records. Muscle necrosis and localized haemorrhage were associated with H. cyclopterina infestation and as described from other definitive hosts.
Growth dynamics of white and red muscle fibres in fast‐ and slow‐growing strains of rainbow trout
Authors: Valente L. M. P. , Rocha E. , Gomes E. F. S. , Silva M. W. , Oliveira M. H. , Monteiro R. A. F. , Fauconneau B.
Published: April 2005

Compared with fish of a slow‐growing strain, fast‐growing rainbow trout exhibited significantly smaller white fibre diameters, throughout development from hatching to 24 cm body length, although possessing similar total number of fibres. In contrast, in red muscle, no differences were observed in fibre diameter between the two strains, but the fast growing fish showed a significantly higher number of red fibres. The differences in growth rate between the two strains were related to the mean white fibre diameter and were found to be matched by proportional adjustments in recruitment of new fibres to the growing muscle. Thus, the largest and fastestgrowing strain showed evidence of sustained higher recruitment of muscle fibres that endowed this strain with the potential to maintain rapid somatic growth for longer and accomplish greater muscle growth.
The mysid‐feeding guild of demersal fishes in the brackish zone of the Westerschelde estuary
Authors: Hostens K. , Mees J.
Published: April 2005

The demersal fish fauna of the mesohaline zone of the Westerschelde estuary (south‐west Netherlands) was sampled intensively in the period 1990–1992. Almost 500 beam trawl samples were taken in both subtidal (330 samples) and intertidal (144 samples) habitats. These yielded 44 fish species, mostly as juveniles. The area functioned as a nursery for several demersal fish species, and harboured large populations of hyperbenthic mysids. Three gobies, three flatfish, one clupeoid and one gadoid dominated the fish fauna, while three mysid species were important components of the holohyperbenthos. From c. 1500 stomach contents of 25 fish species, 44 prey species were identified, the most abundant of which were also common in the hyperbenthal. The demersal fish community consisted of a group that foraged subtidally on fast‐moving epi‐and hyperbenthic prey (for example gadoids, gobies and clupeoids) and a group that foraged on slow‐moving or sessile endobenthic organisms, mainly in intertidal areas (for example most flatfish species). Mysidacea occurred in >50% stomachs analysed and were taken as prey by 19 of the 25 fish species. Mysids were most important in the diets of Pomatoschistus minutus, P. lozanoi, Trisopterus luscus and Merlangius merlangus, and were present in appreciable numbers in Pleuronectes flesus, Trigla lucerna, Clupea harengus and Pleuronectes platessa. These species fed mainly on the brackish water endemic Neomysis integer. Mesopodopsis slabberi (present in 35% of the gobiid stomachs) and Gastrosaccus spinifer(present in 25% of the gadoid stomachs) were of secondary importance. P. minutus and T. luscus showed a diet shift from calanoids (Eurytemora aYnis and Temora longicornis) to mysids at LS of 30 and 50 mm, respectively. Only 1% of the standing stocks of the N. integer and M. slabberi populations was removed by the local demersal fish community, so top–down control of mysid populations in estuaries seems unlikely.
The response of sea bream following abrupt hyposmotic exposure
Authors: Kelly S. P. , Woo N. Y. S.
Published: April 2005

The response of a marine teleost, silver sea bream Sparus sarba, to abrupt hyposmotic exposure was investigated over a 120‐h period following direct exposure from sea water (SW, 33‰) to a hyposmotic environment of 6‰. Aspects of serum chemistry, stored metabolites and gill morphology were used to gain further insight into the biochemical, physiological and morphological alterations that take place following low salinity exposure of a marine fish. Rapid (<1 h) reductions in serum [Cl−] occurred while serum [Na+] exhibited only transient perturbations during initial exposure. Serum total [Ca] declined 24 h after exposure and returned to pre‐exposure levels by 120 h. Despite a tendency for muscle moisture to increase during the early stages of low salinity exposure to significant change could be detected. The response of the branchial chloride cell (CC) was rapid, with apical and fractional exposure area increasing after 6 h. The number of CCs exposed at the branchial surface reduced after 6 h but subsequently increased to elevated levels. Serum cortisol levels had increased three fold 1 h after hyposmotic exposure and stabilised at pre‐exposure levels within 12–24 h. Serum triiodothyronine (T3) levels exhibited a biphasic response, significantly elevating and decreasing after 3 and 6 h respectively. Significant post‐hyposmotic exposure elevations in serum glucose and protein occurred after 1 h, peaking at 3 h and returning to lower levels after 6 h. Total free ninhydrin reactive substances were significantly elevated 3 h post‐hyposmotic exposure, a phenomenon attributable to elevated levels of ammonia, alanine, arginine, glycine, isoleucine, lysine, methionine, phenylalanine, serine, taurine, threonine and valine. Of these substances, glycine, lysine, serine and taurine remained elevated for up to 12 h or longer. Serum urea levels elevated 1 h after exposure to 6%‰ and returned to SW levels 3 h post‐exposure. The relevance of these results is discussed within the context of current knowledge on the effects of hyposomotic adaptation on marine fish.
Prior residence, aggression and territory acquisition in hatchery‐reared and wild brown trout
Authors: Deverill J. I. , Adams C. E. , Bean C. W.
Published: April 2005

In an artificial stream environment, established wild brown trout initiated 44% of the mean aggressive acts whilst hatchery‐reared trout initiated 34% and introduced wild trout initiated 22%. Established wild fish maintained home stations closer to a point source of feed than did both hatchery‐reared and introduced wild conspecifics. Established wild fish were the only group to show a positive mean specific growth rate during the trials. Introduced wild fish showed a slightly negative mean specific growth rate, whilst introduced hatchery‐reared fish exhibited a considerable negative mean specific growth rate. These results suggest that established wild brown trout in a semi‐natural stream environment display a prior‐resident effect over late introductions of hatchery‐reared and wild conspecifics. Introduced hatcheryreared fish were more aggressive and exhibited a lower mean specific growth rate than simultaneously stocked wild fish, suggesting that excessive expenditure of energy for unnecessary aggression may contribute to the poor survival of hatchery‐reared fish after they are stocked into streams.
A comparison of the growth of radio‐tagged and dye‐marked pike
Authors: Jepsen N. , Aarestrup K.
Published: April 2005

Radio‐tagged and dye‐marked adult pike Esox lucius L. were recaptured in a reservoir 1 year after tagging. There was no significant difference in length or weight growth rate between the two groups of fish and no change in their condition factor.
Description of Ophidion saldanhai sp. nov. from the Cabo Verde Islands
Authors: Matallanas J. , Brito A.
Published: April 2005

Ophidion saldanhai sp. nov. is characterized by the following combination of characters: four gill rakers on the lower limb of the first gill arch; 17 pectoral rays; rostral spine strong, triangular in section and with dorsal ridge; predorsal region naked; posterior part of the orobranchial chamber, gill arches and gill rakers blackish; foregut and stomach black, hindgut pale.
Diet comparison between pelagic and demersal whiting in the North Sea
Authors: Pedersen J.
Published: April 2005

Pelagic North Sea whiting Merlangius merlangus preyed upon (pelagic) sprat and sandeel, while demersal whiting preyed upon (demersal) Norway pout and herring. Values of diet breadth were low for both feeding groups using Levin's index. Diet overlaps within layers were low (D <0·25), while the between layer food overlap was moderate (D=0·25–0·74) to high (D >0·74) using Schoener's index. Selection of prey was density dependent. However, prey size also played an important role. The diet of whiting shifted from amphipods and mysids to fish with increasing predator length, and the length of prey consumed increased significantly with length of whiting. The fact that the stomach contents differed between the feeding groups demonstrates the need for a sampling design that includes both pelagic and demersal habitats when trying to quantify the diet of whiting.
Two records of sea lamprey from the north Aegean Sea
Authors: Economidis P.S. , Kallianiotis A. , Psaltopoulou H.
Published: April 2005

Two adult sea lampreys Petromyzon marinus, one female and one male, 742 and 645 mm LT respectively, were caught in the north Aegean Sea, Greece (Vistonis bay and shore of Karvali). These two records are the first for the Aegean Sea and for the whole eastern Mediterranean.
Phenotypic plasticity in the growth of the self‐fertilizing hermaphroditic fish Rivulus marmoratus
Authors: Lin H.‐C. , Dunson W. A.
Published: April 2005

Temperature, salinity, food ration and interactions among them had significant effects on overall growth of hatchlings of the self‐fertilizing hermaphrodite Rivulus marmoratus. Low temperature (19° C) suppressed growth. At 26° C, the treatment groups at 12 and 40‰ salinity had higher final wet masses than the group at 1‰. When provided with high food ration, individuals whose parents were provided with low food had a significantly higher specific growth rate in the first month than those whose parents were provided with high food ration. This effect was also found in the final wet masses. It appears that genetic variation in this species occurs only between strains, yet within a strain there is considerable scope for phenotypic plasticity. The combination of a fixed genotype and plastic expression, along with a suite of specialized physiological characteristics, may explain how a self‐fertilizing hermaphrodite can thrive in such an abiotically stressful and variable habitat as an estuary.
The North Mediterranean Barbus lineage: phylogenetic hypotheses and taxonomic implications based on allozyme data
Authors: Tsigenopoulos C. S. , Karakousis Y. , Berrebi P.
Published: April 2005

On the basis of distinct ecological and morphological characters, the European Barbus taxa have been clustered in two groups: a fluvio‐lacustrine and a rheophilic or strictly riverine one. These two groups (or ecophenotypes) were recognized in different parts of Europe, and formed either a species assemblage (Barbus barbus group) or a polytypic species (Barbus meridionalis). The hypothesis was that species of the same group belong to the same phylogenetic lineage (clade) and are the result of the same transcontinental colonization event. The analysis, using allozyme markers, of 10 taxa of the genus Barbus from France, Italy, Greece, the Czech Republic and Slovakia, showed that the taxa thought to belong to the fluvio‐lacustrine and the rheophilic groups are not monophyletic. The results suggest that probably in each sub‐region, the founding taxon has diverged independently to form species of two different ecophenotypes, one occupying the upstream rivers and the other the lowland rivers. Accordingly, Barbus species groups represent clusters of morphologically convergent taxa living in equivalent biotopes.
The ontogeny of antipredator behaviour in paradise fish larvae III. Size‐related avoidance of predator models
Authors: Miklósi Á. , Csányi V.
Published: April 2005

A series of laboratory experiments examined the effect of the size of predator models on the behaviour of larval paradise fish Macropodus opercularis L., of different age (15 and 20 days old). In a small runway, individually tested larval paradise fish could approach a model predator of different size, with or without eyespots. The duration of approach, the number of fleeings and backings were measured. Fifteen‐day‐old larvae showed similar moderate level avoidance to all models but fled more in the presence of larger models. The approach behaviour in 20‐day‐old larvae depended on the size of the model but only if it had eyespots, and larvae fled and backed more with increasing size of the model. However, manipulation of larval length within age category had no effect on predator avoidance. Since the recognition of the two eyespots seems to be age dependent, it is hypothesized that only larvae older than 20 days will behave in a ‘threat‐sensitive’ manner in the presence of predator models by avoiding larger ones.
Plasma and ovarian thyroxine levels in relation to sexual maturation and gestation in female Sebastes inermis
Authors: Kwonm J. Y. , CHANG Y. J. , Sohn Y. C. , Aida K.
Published: April 2005

Plasma T4 (L‐thyroxine) concentrations in the viviparous rockfish Sebastes inermis showed a peak (119·3±27·8 ng ml−1) during the development of embryos. Ovarian T4 concentrations increased during vitellogenesis and final maturation and decreased during embryogenesis.However, total T4 content within the ovary increased continuously up to the larval stages. Plasma oestradiol‐17β, (E2) concentrations peaked at the final maturation stage and then recovered to the level seen during the non‐reproductive periods. Plasma testosterone (T) concentrations showed a peak (5·33±1·08 ng ml−1) at the embryo stage and high levels were maintained throughout the gestation period. Plasma T4 concentrations during the embryo stage and ovarian T4 content during vitellogenesis were much higher than the levels reported in oviparous fishes. These data suggest that in viviparous rockfish, T4 may be required for sustaining gestation or embryo development within the maternal body. In addition, the high content of total T4 in the ovary implies that there probably does exist a maternal‐embryo relationship during gestation as well as during vitellogenesis.
Obligate feeding of cichlid eggs byCaecomastacembelus zebratusin Lake Tanganyika
Authors: Ochi H. , Sato Y. , Yanagisawa Y.
Published: April 2005

This study examined food habits of four common species of spiny eels (Mastacembelidae) in Lake Tanganyika to find if they eat cichlid eggs and larvae. Diets ofCaecomastacembelus zebratusconsisted nearly exclusively of eggs of substratum‐brooding cichlids, whereas two other species fed on eggs only facultatively and one species never did. More than half individuals ofC. zebratushad empty guts, although the mean weight of their gut contents was highest. This spiny eel ate many eggs in the first and second quarters of the lunar cycle when the spawning of substratum‐brooding cichlids was active, while it nearly ceased eating in the latter half of the cycle. It is suggested that this fish is an obligate egg‐eater and one of the predators that cause the high mortality of early cichlid broods.
Identification of Atlantic salmon × brown trout hybrids with a nuclear marker useful for evolutionary studies
Authors: Perez J. , Martinez J. L. , Moran P. , Beall E. , Garcia‐Vazquez E.
Published: April 2005

A new nuclear DNA marker is described to identify Atlantic salmon, brown trout, and their hybrids. Species‐specific banding patterns are obtained by digestion of genomic DNA with the restriction endonuclease Sac I and hybridization with a histone DNA probe. FISH analyses in hybrid metaphases illustrate the potential of interspecific hybrids for evolutionary studies.
The UV visual world of fishes: a review
Authors: Losey G. S. , Cronin T. W. , Goldsmith T. H. , Hyde D. , Marshall N. J. , McFarland W. N.
Published: April 2005

Ultraviolet‐A radiation (320–400 nm) is scattered rapidly in water. Despite this fact, UV is present in biologically useful amounts to at least 100 m deep in clear aquatic environments. Discovery of UV visual pigments with peak absorption at around 360 nm in teleost cone photoreceptors indicates that many teleost fishes may be adapted for vision in the UV range. Considering the characteristic absorption curve for visual pigments, about 18% of the downwelling light that illuminates objects at 30‐m depth would be available to UV‐sensitive cones. Strong scattering of UV radiation should produce unique imaging conditions as a very bright UV background in the horizontal view and a marked veiling effect that, with distance, obscures an image. Many teleosts have three, or even four, classes of cone cells mediating colour vision in their retina and one can be sensitive to UV. These UV‐sensitive cones contain a visual pigment based on a unique opsin which is highly conserved between fish species. Several powerful methods exist for demonstration of UV vision, but all are rather demanding in terms of technique and equipment. Demonstration that the eye lacks UV‐blocking compounds that are present in many fish eyes is a simpler method that can indicate the possibility of UV vision. The only experimental evidence for the use of UV vision by fishes is connected to planktivory: detection of UV‐opaque objects at close range against a bright UV background is enhanced by the physical properties of UV light. Once present, perhaps for the function of detecting food, UV vision may well be co‐opted through natural selection for other functions. Recent discovery that UV vision is critically important for mate choice in some birds and lizards is a strong object lesson for fish ecologists and behaviourists. Other possible functions amount to far more than merely adding a fourth dimension to the visible spectrum. Since UV is scattered so effectively in water, it may be useful for social signalling at short range and reduce the possibility of detection by other, illegitimate, receivers. Since humans are blind to UV light, we may be significantly in error, in many cases, in our attempts to understand and evaluate visual aspects of fish behaviour. A survey of the reflectance properties of skin pigments in fishes reveals a rich array of pigments with reflectance peaks in the UV. For example, the same yellow to our eyes may comprise two perceptually different colours to fish, yellow and UV‐yellow. It is clearly necessary for us to anticipate that many fishes may have some form of UV vision.
Maturation, fecundity, and intertidal spawning of Pacific sand lance in the northern Gulf of Alaska
Authors: Robards M. D. , Piatt J. F. , Rose G. A.
Published: April 2005

Pacific sand lance Ammodytes hexapterus in Kachemak Bay, Alaska, showed no sexual dimorphism in length‐to‐weight (gonad‐free) ratio or length‐at‐age relationship. Most matured in their second year, males earlier in the season than females, but females (31%) attained a higher gonadosomatic index than males (21%). Sand lance spawned intertidally once each year in late September and October on fine gravel or sandy beaches soon after the seasonal peak in water temperatures. Sand lance in Cook Inlet and Prince William Sound displayed similar maturation schedules. Schools were dominated 2: 1 by males as they approached the intertidal zone at a site where spawning has taken place for decades. Sand lance spawned vigorously in dense formations, leaving scoured pits in beach sediments. Fecundity of females (93–199 mm) was proportional to length, ranging from 1468 to 16 081 ova per female. About half of the overall spawning school fecundity was derived from age group 1 females (55% of the school by number). Spawned eggs were 1·02 mm in diameter, demersal, slightly adhesive, and deposited in the intertidal just below the waterline. Sand lance embryos developed over 67 days through periods of intertidal exposure and sub‐freezing air temperatures.
The movements of pikeperch in a shallow reservoir
Authors: Jepsen N. , Koed A. , ØKland F.
Published: April 2005

The movements of 12 female (62–74 cm) and eight male pikeperch (55–64 cm) radiotagged in early March 1997 in the shallow and turbid Bygholm Reservoir, peaked during the summer, but all fish were also active during the winter. Females moved more than males and their activity was correlated with water temperature. Rate of movement was correlated positively with body size for both male and female pikeperch. During the breeding season (April–May) males became stationary for 14–47 days. Spawning sites, inferred from movements of males, were at depths of 2·0–2·5 m on hard substrata, mainly gravel in areas with many submerged trees and shrubs. Males tended to use the same spawning site the next year. Diel activity pattern varied seasonally but activity was highest from 1800 to 2400 hours.
Biochemical characteristics and antibiotic properties of the mucous envelope of the queen parrotfish
Authors: Videler H. , Geertjes G. J. , Videler J. J.
Published: April 2005

The mucous cocoon of the queen parrotfish is an extensive disulphate bonded network of small glycoproteins of about 21 kDa apparent molecular weight. N‐terminal amino acid sequencing revealed a unique sequence of the first 25 amino acids. Sonicated samples of mucus and the dialysed newly discovered protein inhibit bacterial growth.
Differential expression of two MyoD genes during early development of the trout: comparison with myogenin
Authors: Rescan P. Y. , Delalande J. M. , Gauvry L. , Fauconneau B.
Published: April 2005

In the trout Oncorhynchus mykiss genome, two distinct MyoD genes (TMyoD and TMyoD2) and a single myogenin gene (Tmyogenin) have been identified. The two MyoD genes are believed to arise from a recent tetraploidization of the salmonid genome. During the anterior‐to‐posterior wave of somite formation, the TMyoD transcript is present initially in adaxial cells of both the presomitic mesoderm and the forming somites. A lateral extension of TMyoD labelling is observed in maturing somites when progressively they acquire the characteristic chevron shape. In contrast, the initial expression of TMyoD2 takes place in somites which have been formed already and is limited to cells of the posterior domain of the somites. Later, when all the myotomes have acquired their chevron shape, TMyoD2 transcript disappears progressively from the inner part of the myotomes until it is present only in the superficial part where slow oxidative fibres differentiate. The expression of Tmyogenin is detected first in adaxial cells of forming somites. Shortly after the formation of the somite, Tmyogenin expression extends from the adaxial cells to the posterior lateral regions of the somites and then progresses towards the anterior region. TMyoD, TMyoD2 and Tmyogenin are dynamically and differentially expressed in the developing somite suggesting that they are playing distinct roles in the early myogenesis of trout.
Temperature and neuromuscular development in the tambaqui
Authors: Vieira V. L. A. , Johnston I. A.
Published: April 2005

The development of muscle innervation pattern was investigated in larvae of the Amazonian fish, the tambaqui Colossoma macropomum. The time to hatching decreased from 28–29 h at 23.5° C to 11–12 h at 31° C. The larvae hatched after the completion of somitogenesis (38‐somite stage) at 23.5° C but only at the 33‐somite stage at 28–31° C. Embryos were stained for acetylcholinesterase activity and with an acetylated tubulin antibody in order to visualize neural processes. All muscle fibre types were initially innervated at their myoseptal ends. The development of motor innervation to the trunk muscle was delayed with respect to hatching at higher temperatures. At hatching, muscle fibres were innervated only to somites 16–17 at 28–31° C and somite 23–26 at 23.5–25° C (counting from the head), although the larvae swam vigorously to avoid sinking. In contrast, in newly hatched larvae myofibrils were present right along the trunk at all temperatures in both the superficial and inner muscle fibres. At hatching numerous multi‐layered membrane contacts with the ultrastructural characteristics of gap junctions, were found between muscle fibres and at the inter‐somite junctions, suggesting the somites were initially electrically coupled. These structures disappeared concomitant with the development of muscle endplates right down the trunk. The larvae started feeding 5 days post‐hatch at 28° C. First feeding was associated with a dramatic decrease in the volume density of mitochondria and an increase in the volume density of myofibrils in the inner muscle fibres. The polyneuronal and multi‐terminal pattern of innervation characteristic of adult slow‐muscle fibres also developed around the time of first feeding.
Myogenic patterns in teleosts: what does the present evidence really suggest?
Authors: Stoiber W. , Haslett J. R. , Sänger A. M.
Published: April 2005

As yet, our understanding of teleost muscle development has relied upon interpretation of a variety of studies of a small number of different species, spanning the tropics to the North Atlantic, sea water to fresh water. The zebrafish Danio rerio has become the most widely used model species for laboratory‐based investigations of the earliest steps of developing muscle architecture. The present pattern of teleost muscle formation is likely to provide a common basis for understanding the variety of mechanisms that control myogenesis, but is not yet tested for its applicability to fish from a wide variety of teleost taxa. Using examples from different areas of developmental research in fish, it is argued that a more flexible and dynamic scheme of muscle development needs to be envisaged. This would extend the present basic pattern to encompass expression of the full spectrum of ecological and evolutionary variation, particularly in relation to rate of muscle development and final morphology.
Ontogeny of routine swimming speed and startle responses in red drum, with a comparison of responses to acoustic and visual stimuli
Authors: Fuiman L. A. , Smith M. E. , Malley V. N.
Published: April 2005

Routine swimming speed of larval red drum Sciaenops ocellatus increased throughout development but most rapidly for larvae >10 mm LT. Red drum of all sizes swam faster than predicted by published summary equations based on other species, possibly due to more advanced development at a given length. Frequency and magnitude of startle responses increased over the larval period for both types of stimuli with most of the improvement taking place before larvae reached 8 mm LT. Time to response for an acoustic and visual stimulus decreased early in the larval period but levelled off after 10 mm LT. Response distance and response speed for both stimuli generally increased throughout the larval period, but response duration remained constant. Visually stimulated responses were generally longer in duration and distance covered than acoustically stimulated responses, while mean response speeds were similar.
Seasonal changes of thyroid hormones in field‐collected Atlantic cod in relation to condition indices, water temperature and photoperiod
Authors: Comeau L. A. , Campana S. E. , Hanson J. M. , Chouinard G. A.
Published: April 2005

Serum T4 and T3 in wild Atlantic cod Gadus morhua ranged from 1 to 12 ng ml−1 and from 2 to 27 ng ml−1 respectively over a 3‐year period. In general, the concentrations increased from summer (T3) or early autumn (T4) to maxima in mid‐winter and declined abruptly during spring. The T4/T3 monthly means were lowest in summer and highest in winter. The seasonal patterns of thyroid hormones were weakly correlated with changes in water temperature. However, both T4 and T3 co‐varied simultaneously with photoperiod. In addition, T3 was correlated with the hepatosomatic index and condition factor during summer and autumn. It is suggested that the seasonal changes in the release of T4 from the thyroid were photoperioddriven, and that the course of T3 was regulated by the metabolic state of the fish during the somatic growth period.
Effects of food deprivation on 24 h‐changes in brain and liver carbohydrate and ketone body metabolism of rainbow trout
Authors: Figueroa R. I. , Rodríguez‐Sabarís R. , Aldegunde M. , Soengas J. L.
Published: April 2005

Plasma glucose, lactate and acetoacetate, brain glycogen and acetoacetate, and liver acetoacetate, glycogen and lactate in fed rainbow trout exhibited daily changes. However, no daily changes were observed in the activities of the brain enzymes glycogen synthetase, 6‐phosphofructo 1‐kinase, and lactate dehydrogenase. Depending on the length of the previous fasting period most daily changes observed in the metabolic parameters of fed fish disappeared, except for liver acetoacetate levels, which displayed daily changes in both fed and fasted fish. These results suggest that feeding is an important factor regulating most daily changes in the brain and liver carbohydrate and ketone body metabolism of rainbow trout.
Spacing of wild schooling herring while encircled by killer whales
Authors: Domenici P. , Batty R. S. , Similä T.
Published: April 2005

Herring (Clupea harengus) schools encircled by killer whales Orcinus orca and swimming under threat, show higher compaction than previous data on undisturbed herring but do not show maximum compaction as it would be predicted on theoretical grounds.
Comparing acoustic model predictions to in situ backscatter measurements of fish with dual‐chambered swimbladders
Authors: Horne J. K. , Walline P. D. , Jech J. M.
Published: April 2005

Lavnun Mirogrex terraesanctae have a dual‐chambered swimbladder and are the dominant fish species in Lake Kinneret, Israel. Bi‐monthly acoustic assessments are used to monitor lavnun abundance but the relation between the amount of reflected sound and organism morphology is not well described. Predictions from Kirchho.‐ray mode (KRM) backscatter models show a sensitivity of echo amplitude to fish length and fish aspect. Predicted mean KRM target strengths matched maximum in situ target strength measurements of eight tethered fish within 2·5 dB at 120 kHz and within 7 dB at 420 kHz. Tilt and roll of lavnun during tethered measurements increased variance of backscatter measurements. Accurate abundance and length frequency distribution estimates cannot be obtained from in situ acoustic measurements without supplementary net samples.
Effects of hanging ice dams on winter movements and swimming activity of fish
Authors: Brown R. S. , Power G. , Beltaos S. , Beddow T. A.
Published: April 2005

Formation of a hanging dam, a large, thick sub‐surface accumulation of frazil ice that blocked river flow, altered physical environmental conditions dramatically and common carp Cyprinus carpio, and brown trout Salmo trutta, evacuated the pool in which the dam developed. A mean of 80·1% of the pool volume was filled with frazil ice. Mean and bottom water velocities in the pool increased from 6 to 27 cm s−1 and from 4 to 21 cm s−1, respectively, when the hanging dam formed, and water depth decreased from a mean of 2·25 to 0·45 m. Activity levels of fish leaving the pool varied. Two carp had higher swimming activities when in the over wintering pool, compared to the period when they were out of it, and a third showed opposite results.
Comparison of growth, diet and food consumption of sea‐run and lake‐dwelling Arctic charr
Authors: Rikardsen A. H. , Amundsen P.‐A. , Bjørn P. A. , Johansen M.
Published: April 2005

Sea‐run post‐smolt Arctic charrSalvelinus alpinus, (15–26 cm) from Storvatn, northern Norway (70°39′48″N) had significantly higher average specific growth rates in two years (1·64 and 1·66) than the corresponding lake‐dwelling charr (0·53 and 1·20). The post‐smolts displayed fast compensatory growth in the first 2–3 weeks of their sea residency, but then almost stopped growing prior to their return to fresh water. Lake‐dwelling charr grew more evenly during the same time period. Thus, the anadromous charr may return to the lake after only 5–6 weeks in the sea, because the potential to maintain a high growth rate in the sea is reduced. The marine diet consisted mainly of the two crustacean plankton speciesCalanus finmarchicus, andThysanoëssa, sp. (88%), and less of fish (6%), insects (4%) and benthos (2%). The diet of lake‐dwelling charr consisted mainly of insects (58%, mostly chironomid pupae) and zoobenthos (29%), and less of zooplankton (13%) during the same time period. Although post‐smolts had the highest growth rates, they had significantly lower food consumption rates and higher frequencies of empty stomachs than the corresponding lake‐dwelling fish. Possible explanations for this paradox are discussed in relation to stomach evacuation rates, water temperature, feeding behaviour and the energy content of the food in the two environments.
Countergradient variation in growth and food conversion efficiency of juvenile turbot
Authors: Imsland A. K. , Foss A. , Névdal G. , Cross T. , Bonga S. W. , Ham E. A. , Stefansson S. O.
Published: April 2005

Growth performance of a high latitude (Norway) population of juvenile turbot Scophthalmus maximus, was superior to that of two other lower latitude populations (Scotland, France) especially at 18° and 22° C. Overall these results lend some support to the hypothesis of countergradient variation in growth. The Norwegian population had the highest estimated temperature optimum for growth (Topt.G, ±S.E.) (23·0±0·9°C) and food conversion efficiency (Topt.Ec) (17·5±0·3), followed by the French (Topt.G 21·1±1·0; Topt.Ec, 16·7±0·1) population, whereas the Scottish population had the lowest optimum (Topt.G, 19·6±0·6; Topt Ec, 16·5±0·1°C). These results have two major implications: firstly, for turbot culture, particularly in selection work focusing on growth performance; secondly, if countergradient variation in growth performance takes place within a species one cannot assume automatically that one set of physiological parameters, in this case growth‐related parameters, is satisfactory to predict growth for a species throughout its range as different populations might show a difference in response towards different physiological parameters.
Differences in size and growth rates of male and female migrating Japanese eels in Pearl River, China
Authors: Tzeng W. N. , Lin H. R. , Wang C. H. , Xu S. N.
Published: April 2005

The Sr/Ca ratios in otoliths of silver Japanese eels Anguilla japonica, in Pearl River, China, indicated that both sexes did not stay in brackish water and grew in fresh water from the glass eel stage until spawning migration. This did not support the hypothesis that females tended to distribute upstream and males might be restricted to estuaries. The back‐calculated total length of males at glass eel stage was not significantly different from that of females, indicating that the hypothesis that small glass eels became males and larger ones became females may not be true. The mean (±S.D.) age and total length of males at migration were 6·4±1·6 years and 48·3±4·5 cm, which were significantly smaller than for females, 8·3±1·6 years and 61·4±4·1 cm. The age of migration was related inversely to growth rate for both sexes. Growth parameters of the von Bertalanffy growth equation were K=0·21 cm year°1, L∞=55·7 cm and to=‐0·55 year for males and K=0·14 cm year−1, L∞=77·5 cm and to=‐0·60 year for females. The difference in asymptotic length (L∞) between males and females may be because females postpone migration to achieve larger size for maximizing reproductive success.
Consumption of deep‐sea shrimp by bigeye flounder Hippoglossina macrops in fishing grounds off northern Chile
Authors: Villarroel J. C. , Acuña E.
Published: April 2005

Feeding of the bigeye flounder Hippoglossina macrops on the shrimp Heterocarpus reedi was analysed between 20 November and 4 December 1995. Feeding on H. reedi intensified between 0900 and 1600 hours with a second, smaller peak between 2300 and 0200 hours. Assuming an exponential gastric evacuation model, the gastric evacuation rate was estimated as 0·197 %W h −1 (95% CI=0·025–0·369). The daily ration decreased latitudinally from north to south from 3·62 to 2·66 and from 2·06 to 0·41 %W, respectively. Consumption was related positively to shrimp biomass and influenced by flounder size structure in the three fishing zones analysed and was estimated as 0·08–0·02% of the total shrimp biomass.
Seriola carpenteri: a new immigrant in the Mediterranean from the Atlantic Ocean
Authors: Pizzicori P. , Castriota L. , Marino G. , Andaloro F.
Published: April 2005

In September 1997, 148 mature Guinean amberjacks Seriola carpenteri, were caught by purse seine o. Lampedusa Island at 20 m depth, the first record of this Atlantic species in the Mediterranean.
Gonadal development in triploid Heteropneustes fossilis
Authors: Tiwary B. K. , Kirubagaran R. , Ray A. K.
Published: April 2005

Gonadosomatic index (IG) and germ cell numbers in seminiferous tubules were significantly reduced in triploid male catfish compared with diploids. Triploid females had lower IG than diploids, with atretic follicles in their ovaries during prespawning and spawning phases.
Allozyme analyses of the genus Trisopterus: taxonomic status and population structure of the poor cod
Authors: Mattiangelli V. , Bourke E. A. , Ryan A. W. , Mork J , Cross T. F.
Published: April 2005

Genetic analysis of the four Trisopterus (Gadidae) taxa suggests that the interrelationships of the two morphs of poor cod (T. minutus minutus in the Atlantic and T. minutus capelanus in the Mediterranean) should be reconsidered. The Mediterranean poor cod T. m. capelanus is more closely related to bib T. luscus than to the Atlantic poor cod, so the population structure in the Atlantic and Mediterranean poor cod must be considered separately. Among 635 Atlantic individuals there was some evidence of poor cod population differentiation (allele frequency heterogeneity test P <0·0005; FST=0·0135, P≤0·0005). Levels of genetic variation were similar to those reported for related gadoid species. Some differentiation was present on the Norwegian coast (samples from Trondheimsfjord) and between the Faeroe Islands (Faeroe Bank) and the adjacent European coastal location. In contrast no statistically significant population differentiation was evident in Mediterranean poor cod, but fewer samples and individuals were screened.
Scaling of enzyme activity in larval herring and plaice: effects of temperature and individual growth rate on aerobic and anaerobic capacity
Authors: Overnell J. , Batty R. S.
Published: April 2005

Herring Clupea harengus and plaice Pleuronectes platessa were reared at 8 and 12° C from the fertilized egg to a larval age of up to 600 degree‐days. Soluble protein as well as the activities of both citrate synthetase (CS) and lactate dehydrogenase (LDH) were measured in homogenate supernatants of individual larvae at 10° C. Scaling factors were calculated using the expression y=axb where y is the enzyme activity, x the protein content of the larva a is a constant and b the scaling factor. All scaling factors showed significant differences between the species. Within species, the scaling factors for CS activity were either small or not significantly different between the two rearing temperatures, but the scaling factors for the LDH activities were significantly different at the two temperatures for both species. Herring larvae, which had higher LDH activities when newly hatched, showed smaller scaling factors for LDH (b=1·42 at 8°C and b=1·07 at 12° C) than plaice (b=2·11 at 8°C and b=1·45 at 12° C). Activities converged as the larvae grew. The results of the current study together with reanalysis of data from the literature indicate an increasing aerobic and anaerobic capacity during the larval stage of fishes (positive allometry).