bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular systematics of the Atlanto‐Mediterranean Solea species
Authors: Tinti F. , Piccinetti C.
Published: April 2005

Within the genus Solea, four sister lineages have been evolved that actually correspond to the species S. vulgaris, S. senegalensis, S. kleini and S. lascaris. The existence of S. aegyptiaca and S. impar is not supported and these species can be synonymized under S. vulgaris and S. lascaris, respectively. This pattern of taxonomy agrees fully with that proposed by Ben‐Tuvia (1990; Journal of Fish Biology 36, 947–960) based on morphological features. In addition, mtDNA data contradict the widely accepted relatedness between S. kleini and S. lascaris based on the shared enlarged forenostril on the blind side. A sample of soles clearly related to S. senegalensis was caught in the Gulf of Taranto (Ionian Sea), representing the most western finding of this species in the Mediterranean Sea.
Life‐history strategies and protein metabolism in overwintering juvenile Atlantic salmon: growth is enhanced in early migrants through lower protein turnover
Authors: Morgan I. J. , McCarthy I. D. , Metcalfe N. B.
Published: April 2005

The specific growth rate (length) of early migrant juvenile Atlantic salmon Salmo salar was significantly greater than that of delayed migrants in November and February. However, there were no differences in the fractional rate of protein synthesis (ks) of white muscle tissue between the migrant groups at any time. Early migrants had significantly greater fractional rates of protein growth (kg) of white muscle in February and significantly lower fractional rates of protein degradation (kd) in May. These results suggest that, compared to delayed migrants, Atlantic salmon adopting the strategy of early seaward migration maximize their overwinter growth by minimizing their rate of protein turnover.
Size‐dependent mortality of juvenile Atlantic cod, estimated from recaptures of released reared cod and tagged wild cod
Authors: Kristiansen T. S. , Otterå H. , Svåsand T.
Published: April 2005

The recapture rate and survival of reared cod Gadus morhua L. (15–45 cm) released in fjords and open coastal areas of Norway increased with increasing size at release, while release area and season also had a significant influence on the results. High mortality soon after release reduced the number of released fish by more than two–thirds within 6 months, and reduced the potential commercial yield to a low level. In most cases the recapture yield was lower than the released biomass and the net yield increased little or not at all with increasing size at release. In western Norway high fishing mortality of young fish reduced the numbers of surviving fish rapidly and the growth overfishing reduced the potential yield still further. Natural mortality decreased with increasing size at release, and became low when the fish approached their size refuge, i.e. when they could not be eaten by their usual predators.
Abundance and distribution of Diphyllobothrium ditremum Creplin (Cestoda: Pseudophyllidea) plerocercoids in benthic whitefish, in northern Finnish Lapland
Authors: Tolonen A. , Rita H. , Peltonen H.
Published: April 2005

The prevalence of Diphyllobothrium ditremum plerocercoids in whitefish Coregonus lavaretus ranged between 70 and 100% in Lake Kilpisjärvi and in three other lakes in Northern Lapland, Finland. The mean abundance in Lake Kilpisjärvi (age groups 1+‐10+ years), ranged between 103·5± 71·3 in 1992–1993 to 110·9± 80·0 plerocercoids per fish in 1997. The asymptotic value of the infection levelled at 113 plerocercoids per host after age 3. No significant difference in abundance was detected between study years (P>0·10). Abundances in other lakes ranged between 4·8±9·7 and 91·1±115·1. Two seasonal peaks of plerocercoid recruitment were observed in Lake Kilpisjärvi; between March and April (P<0·002) and between September and October (P=0·042). In autumn the numbers of larvae increased particularly in female fish. The invasion rate of the parasite was lower in other lakes studied, and the infection rate in whitefish was closely related to the copepod food eaten.
A test of ecological selection against young‐of‐the‐year hybrids of sympatric sticklebacks
Authors: Vamosi S. M. , Hatfield T. , Schluter D.
Published: April 2005

Ecological selection against hybrids, the reduction in hybrid fitness attributed solely to environmental factors, was tested by introducing young‐of‐the‐year benthic, limnetic and F1hybrid sticklebacksGasterosteus aculeatusto divided experimental ponds and lake enclosures. The frequency of hybrids in samples taken at the end was significantly lower than their frequency at introduction. Hybrid survival was significantly lower in pond‐sides in which they were initially the most common cross type than in pond‐sides in which they were initially rare, suggesting that hybrid survival may be frequency‐dependent. Growth rate of F1hybrids was marginally lower than benthic growth rates, being significantly lower than in ponds and not different in lake enclosures. The diet of hybrids overlapped with both parent species in ponds and with benthic diets in lake enclosures. The results suggest that ecological selection is acting against young‐of‐the‐year hybrid sticklebacks.
Growth of Atlantic Salmon parr in fluvial and lacustrine habits
Authors: Halvorsen M. , Svenning M.‐A.
Published: April 2005

The growth of naturally recruited Atlantic salmonSalmo salarparr in fluvial and lacustrine habitats was investigated in three northern Norwegian watercourses. Salmon parr were sampled in autumn with small mesh gillnets in lakes, and by electrofishing in streams. In three northern Norwegian watercourses, lacustrine Atlantic salmonSalmo salarparr were larger in length and weight at age than fluvial parr. Back‐calculated lengths indicated that lacustrine salmon parr were recruited from the fastest growing part of the populations and they had larger growth (length) increments between age intervals than fluvial parr. There was no consistent pattern in growth comparisons between parr from the inlet and outlet streams. Temperature regime alone could not explain the growth difference observed between parr from the different habitats.
Serum levels of precursors to vitelline envelope proteins (choriogenins) in Sakhalin taimen after treatment with oestrogen and during oocyte growth
Authors: Shimizu M. , Fukada H. , Fujita T. , Hiramatsu N. , Hara A.
Published: April 2005

In Sakhalin taimen Hucho perryi two choriogenins have been identified in serum, designated high‐ and low‐molecular‐weight vitelline envelope‐related protein (hVERP and lVERP). Two immunoassays were developed using specific antibodies; single radial immunodiffusion (SRID) and enzyme‐linked immunosorbent assay (ELISA), for measurement of the precursors to vitelline envelope proteins. ELISA measures hVERP and lVERP in serum at concentrations as low as 16 and 47 ng ml−1, respectively. Using these immunoassays, changes in serum levels of VERP were measured after treatment with E2 and during oocyte growth. When immature 2‐year‐old taimen were injected with 2 mg E2 per kg body weight, both VERPs were induced in serum within 24 h. In the course of the first ovulation, serum VERPs levels increased in September (8 months before ovulation), reached maximum in January, and decreased sharply prior to ovulation in May. These changes generally paralleled that of vitellogenin except for the drastic decrease of VERPs in May.
Novel perspectives in sexual lability through gonadal biopsy in larval sea lampreys
Authors: Lowartz S. M. , Beamish F. W. H.
Published: April 2005

Gonadal biopsies of sea lamprey Petromyzon marinus larvae (118·5–142·5 mm) were examined quantitatively and categorized as ovaries, presumptive testes, or atypical gonads. Subsets of larvae were then killed 1, 2, 4, 8, 16 and 52 weeks following surgery at which time each larva was matched with its biopsy, and its gonad re–examined for quantifiable changes in composition. During 52 weeks, oocyte diameters increased significantly while numbers of oocytes per unit area significantly declined. Germ cell numbers remained within the range of typical presumptive testes. Overall abundance of typical ovaries decreased over the course of the experiment, whereas the number of presumptive testes increased. This was a direct result of presumptive testis development from atypical gonads, oocyte atresia and sex reversal. The results suggest an argument for environmental sex determination in lampreys, while indicating that they remain sexually labile throughout most of the larval period, despite primary differentiation.
Size–dependent mortality of juvenile reared Atlantic cod released in a small fjord
Authors: Kristianen T. S. , Otterå H. , Svåsand T.
Published: April 2005

Less than 2% of the O–group cod Gadus morhua of mean length 8 cm at release survived their first 3 months in the sea, while c. 75% of those of mean length 12 cm survived a similar period. There was no difference in mortality rates during their first winter at sea between groups with mean lengths 12 and 17 cm at release. The results could probably be explained by the relatively small sizes of predatory fishes in the fjord and the degree of overlap between size at release and the preferred prey sizes of the predators.
Cleaning by the wrasse Thalassoma noronhanum, with two records of predation by its grouper client Cephalopholis fulva
Authors: Francini–Filho R. B. , Moura R. L. , Sazima I.
Published: April 2005

The Noronha wrasse Thalassoma noronhanum was recorded cleaning 19 client fish species at Fernando de Noronha Archipelago, o. north–eastern Brazil. The preferred clients were non–dangerous, mostly planktivorous species, whereas the potentially dangerous, predatory species were rarely cleaned. T. noronhanum acts as a cleaner in two distinct ecological situations, at and outside the cleaning stations, and attends different client species in each of them. Potentially dangerous clients were mostly attended outside the cleaning stations. Many attacks and two instances of predation on the cleaner wrasse by the grouper client Cephalopholis fulva were recorded. The attacks occurred on individual wrasses foraging near the bottom outside the cleaning stations.
Growth of larval and juvenile perch: the importance of diet and fish density
Authors: Romare P.
Published: April 2005

In August, growth rate of young–of–the–year (YOY) Perch In lake enclosures could be explained by both YOY density and mean cladoceran biomass, suggesting that in a lake where YOY perch are dominant, growth may be density dependent in late summer and mediated through top–down control on daphnid biomass. In June, growth rate of YOY perch could not be fully explained by YOY density or by mean cladoceran biomass, suggesting that growth and survival during the first part of the summer is negatively affected by a diet of Bosmina and cyclopoid copepods only. The experiments also suggest why YOY perch have a slow growth and a low abundance in eutrophic lakes where small zooplankton dominate. The June experiment also indicated that growth of late larval or early juvenile perch improved when a larger cladoceran became available and was included in the diet.
Density–dependent recruitment of Puntius sophore in floodplain waterbodies in Bangladesh
Authors: Halls A. S. , Debnath† K. , Kirkwood G. P. , Payne A. I.
Published: April 2005

Recruitment of Puntius sophore in floodplain waters of Bangladesh was strongly densitydependent at a range of high stock densities and can be described by a Ricker model. Recruitment at low stock density was correlated strongly with waterbody fertility measured in terms of nitrate concentration. The implications of these results are discussed in terms of community–based management.
The composition and characteristics of skin and muscle collagens from a freshwater catfish grown in biologically treated tannery effuent water
Authors: Sivakumar P. , Arichandran R. , Suguna L. , Mariappan M. , Chandrakasan G.
Published: April 2005

The skin of catfish Gariepinus spp. reared in tannery effuent water (ETP) had an increased collagen content, decreased acid solubility and high carbohydrate association as compared with skin of normal fish. The skin collagen in either fish was composed of three distinct α chains with mobilities different from that of vertebrate type I α chains and two of these three chains were invariably present in the muscle collagen. The amino acid composition of ETP fish skin and muscle collagens were similar but were characterized by higher degrees of proline and lysine hydroxylation, indicating higher stability. Both the skin and muscle collagens had significantly high denaturation temperatures. Electron microscopy of in vitro reconstituted fibrils of skin and muscle collagens of ETP fish displayed defined periodicities of around 64 nm. This demonstrates that the polymorphism in skin collagen chains is not confined to marine fish. There was a close similarity in the composition of skin and muscle collagens and the ETP environment influences the solubility and stability of the skin collagen. It is hypothesized that the third chain may play a role in the anchorage of skin to muscle, as such chain composition is now evident in fish such as hake, cod and catfish where the musculature is strongly attached to the skin.
First records of advanced embryos and egg capsules of Bathyraja skates from the deep north‐eastern Atlantic
Authors: Stehmann M. F. W. , Merrett N. R.
Published: April 2005

Five variously developed embryos [142–279 mm total length (LT)] from egg capsules from the Porcupine Seabight, north‐eastern Atlantic (1541 m depth) are used to establish the ontogeny and early life history of Bathyraja richardsoni. The capsules of this species and two half‐formed ones from the shell glands of a large (1620 mm LT) female Bathyraja pallida taken off Ireland (c. 1900 m depth) are described and illustrated. The varying degree of yolk sac absorption found in the B. richardsoni embryos is discussed in relation to hatching size and its seeming size independence over c. 20–50 mm within the embryos’ total length range. The conservative variation in external morphology with development from advanced embryos to adults among such deep stenobathic Bathyraja skates is commented upon, as is the bathymetric segregation of adults from levels in which egg capsules are deposited and young develop.
Trace elements in otoliths of the two‐banded bream from a coastal region in the south‐west Mediterranean: are there differences among locations?
Authors: Gillanders B. M. , Sanchez‐Jerez P. , Bayle‐Sempere J. , Ramos‐Espla A.
Published: April 2005

There were no significant differences in otolith chemistry (Li, Mn, Sr, Cd, Ba) of Diplodus vulgaris between sites (distances >100 m) and few differences among locations (distance >10 km) along the south‐west coast of Spain. Multivariate analysis of otolith chemistry detected a difference among locations, but a posteriori comparisons could not detect which locations differed. This is one of the few studies to show little variation in otolith chemistry among locations. Of the studies reviewed, <10% showed non‐significant differences. It is suggested that the region of the Mediterranean where this study was conducted may be relatively homogeneous in comparison to estuarine and coastal regions where many of the other studies have been conducted.
Growth of North Alboran Sea sardine larvae estimated by otolith microstructure, nucleic acids and protein content
Authors: Ramírez T. , Cortés D. , Garcíaa A.
Published: April 2005

Wet mass and DNA, RNA and protein content increased significantly with standard length (LS) of sardine Sardina pilchardus larvae, collected in January 1995, in the Bay of Málaga, North Alboran Sea. LS, wet mass and DNA, RNA and protein content were closely related allometrically to otolith radius (R). Larval daily length increments decreased but DNA, protein and wet mass daily increments increased with larval age. Daily length increments showed a negative and poor relationship with long‐term otolith growth. In contrast, DNA, protein and wet mass daily increments were positively correlated. Differences between observed and back‐calculated otolith radius‐at‐age indicated that larvae with slow otolith growth were under represented in older age groups, suggesting the existence of growth‐selective mortality. Recent otolith growth, estimated from the mean widths of the last six increments, increased with age and R. Individual RNA: DNA and protein: DNA ratios were correlated significantly, although weakly, with LS and larval growth.
Effects of reduced salinities on growth, food conversion efficiency and osmoregulatory status in the spotted wolffish
Authors: Foss A. , Evensen T. H. , Imsland A. K. , ØIestad V.
Published: April 2005

No significant differences in mean mass between groups were found at any time in spotted wolffish Anarhichas minor, mean (±S.D.) initial mass 76 (±21) g, reared at salinities of 12, 17, 25 and 34‰ for 12 weeks at 8° C. Salinity did not have a significant effect on daily feeding rates, total food consumption, food conversion efficiency and protein efficiency ratio. Growth trajectories varied between groups, but no overall difference in growth was found. Plasma osmolality and plasma chloride levels decreased with salinity in a 48 h abrupt exposure trial, and in the growth experiment the low salinity groups (12 and 17‰) exhibited significantly lower values compared with 25 and 34‰. The decrease was moderate and concentrations were well within the range described for other marine species. The results indicate that the spotted wolffish is a strong osmoregulator which could be reared at various salinity levels.
Variation in food intake, food conversion efficiency and growth of juvenile turbot from different geographic strains
Authors: Imsland A. K. , Foss A. , Stefansson S. O.
Published: April 2005

Food conversion efficiency and growth of juvenile turbot Scophthalmus maximus, reared under temperatures of 14, 18 and 22° C, were found to be higher in one experiment (7–70 g fish) in a higher latitude (Norway) strain than lower latitude (France and Scotland) strains. In a second study (20–150 g fish), food intake, food conversion efficiency and growth were higher in higher latitude (Iceland and Norway) compared with a lower latitude (France) strain.
Ionic regulation and Na+,K+‐ATPase activity in gills and kidney of the Antarctic aglomerular cod icefish exposed to dilute sea water
Authors: Romão S. , Freire C. A. , Fanta E.
Published: April 2005

When Notothenia neglecta was exposed to diluted, half strength, sea water for 6 h or 10 days, serum concentrations of Cl‐, Na+, K+ and Mg2+ did not differ from those of sea water controls. This indicates that the fish were capable of both short‐ and long‐term regulation. Renal Na+,K+‐ATPase activity decreased after a 6 h exposure to diluted sea water, but there were no differences between diluted sea water and controls after 10 days of exposure.
Development of feeding structures in larval fish with different life histories: winter flounder and Atlantic cod
Authors: Herbing I. Hunt von
Published: April 2005

The size at which feeding structures developed and shifts in head proportions occurred, differed between Atlantic cod Gadus morhua and winter flounder Pseudopleuronectes americanus. The sequence and timing of the development of feeding structures may not be dependent on size, but may occur because they are necessary to meet specific requirements offish larvae feeding in the plankton. In early larval stages development of feeding structures was similar in number and type and was necessary for first‐feeding in both species. In later stages, significant differences between species occurred in the timing of the development of feeding structures. In cod differentiation of new structures and changes in head proportions occurred at about two‐thirds of the way through larval life, which coincided with an increase in growth. In flounder changes in feeding morphology did not occur during the symmetrical larval stage, but occurred only after metamorphosis to the asymmetrical demersal juvenile stage. Differences between cod and flounder in the size at which feeding structures develop may reflect life history adaptations expressed in the duration of the pelagic larval stage, as well as differences in juvenile habitat and feeding ecology.
Alarm pheromone recognition in a Missouri darter assemblage
Authors: Haney D. C. , Vokoun J. C. , Noltie D. B.
Published: April 2005

The a priori null hypotheses that responses to donor, orangethroat darter Etheostoma spectabile, johnny darter Etheostoma nigrum, logperch Percina caprodes, slenderhead darter Percina phoxocephala and blackside darter Percina maculata, extracts would be absent in the three test species, orangethroat darter, johnny darter and logperch, was rejected. This was because orangethroat and johnny darter responded with decreased activity to skin extracts derived from conspecifics and from other members of the assemblage. In contrast, logperch were notable by their lack of a detectable response to any species. Similarities and differences in habitat utilization are seen as a possible basis for these responses.
Thermolabile Sex Determination in honmoroko
Authors: Fujioka Y.
Published: April 2005

In six pairings (one female × three males and vice versa) of honmoroko Gnathopogon caerulescens, although in one pairing the sex ratio of the offspring did not deviate significantly from 1:1, in four pairings the proportion of females decreased significantly with an increase in temperature. Heavy mortality due to disease was observed in the remaining pair. There were highly significant differences in sex ratios among the broods produced by different mothers with the same father and vice versa, and the response of sex ratio to temperature treatments differed considerably within pairings. The progeny of five out of 20 males produced at 34°C were almost all females, two were male‐biased, and the remaining had balanced (1:1) sex ratios. These results suggest that the sex determination system in honmoroko is close to female homogamety but is influenced by temperature, genetic factors and genotype‐temperature interactions.
Return migration of Atlantic Salmon in the River Tana: Phases of migratory behaviour
Authors: ØKlamd F. , Erkinaro J. , Moen K. , Niemelä E. , Fiske P. , McKinley R.S. , Thorstab E. B.
Published: April 2005

From a total of 174 multi‐sea‐winter Atlantic salmon radio tagged in the Tanafjord (northern Norway, 70°N) during 1992 and 1993, 48 Atlantic salmon were followed from entering the River Tana until spawning. Three phases were identified: (1) migratory, direct or stepwise migration to, or close to the position held at spawning; (2) search, movements both up and down river at or close to the position held at spawning; (3) holding, a period without movements prior to spawning. During the migratory phase, Atlantic salmon migrated directly to near the spawning area, or stopped between one and nine shorter periods during the upstream migration. Number of stops increased with increasing migratory distance in 1993, but no such correlation was found in 1992. The highest migratory speeds were recorded in the lower parts of the river. A distinct change in migratory pattern was found in 67% of the Atlantic salmon near or at the area held at spawning. Most common was a search phase of erratic movements with more than one down river movement. After the movement terminated, 96% of the Atlantic salmon had a period when no or little movement was recorded until spawning (on average 55 days in 1992 and 51 days in 1993). There was no preference for staying at, up or down river from the spawning area during this holding period. Early ascending Atlantic salmon migrated to spawning areas further from the mouth than the later arriving Atlantic salmon in 1993, but not in 1992. The proportion of time spent on the migratory phase increased, while the proportion of time spent on the holding phase decreased with increasing distance to the spawning area.
Contrasts in the hypo‐osmoregulatory abilities of a freshwater and an anadromous population of inconnu
Authors: Howland K. L. , Tonn W. M. , Goss G.
Published: April 2005

Juvenile freshwater and anadromous inconnu Stenodus leucichthys regulated plasma ions following a direct transfer from fresh to brackish water (10–15‰), but suffered osmoregulatory collapse with 100% mortality in 48 h when directly transferred to 25‰ salinity. Acclimation to brackish water for 2 weeks improved hypo‐osmoregulatory capacity in both populations, with acclimated fish showing smaller increases in blood plasma ion concentrations, higher Na+‐K+ ATPase activity, and lower mortality than non‐acclimated fish following transfer to 25‰ sea water. Anadromous inconnu maintained pre‐treatment plasma ion levels during acclimation, whereas these levels increased during acclimation in freshwater inconnu. Juvenile anadromous inconnu are therefore able to adapt physiologically to sea water of at least 25‰, if brackish‐water acclimation is available, but freshwater inconnu have diminished saltwater tolerance, relative to the anadromous form.
Temporal and spatial variation in length of larval life and size at settlement of the Hawaiian amphidromous goby Lentipes concolor
Authors: Radtke R. L. , Kinzie R. A. , Shafer D. J.
Published: April 2005

Larvae of the Hawaiian amphidromous goby Lentipes concolor settled after a mean length of larval life (LLL) of 86·2±8·5 days (n=236, range=63–106 days) at a mean size of 16·0±0·7 mm LT (n=154, range=14·1‐17·9 mm). Mean LLL for L. concolor was about twice that typically reported for tropical marine gobiids. Variation in LLL (CV=10%) and size at settlement (CV=4%) were low, and comparable to that for marine gobiids. LLL and LT were weakly positively correlated (Pearson's correlation coefficient r=0·50, P<0·0001). Larvae settled after shorter planktonic lives and at smaller sizes during months with warmer ocean temperatures. Inter‐island variation in LLL did not support a dominant south‐east to north‐west larval drift, following the dominant south‐east to north‐west flow of prevailing currents in the Archipelago. Instead, recruits on Maui Island, centrally located in the archipelago, had shorter LLL than recruits to upstream Hawai'i and downstream Kaua'i islands. These findings have important implications for understanding the complex life history dynamics of amphidromous fishes as well as their management.
Competitive ability is related to metabolic asymmetry in juvenile rainbow trout
Authors: Mccarthy I. D.
Published: April 2005

Of 55 size–matched pairs of juvenile rainbow trout Oncorhynchus mykiss, each consisting of one high and one low relative metabolic rate fish (relative size difference <5%), the high relative metabolic rate fish was dominant in 36 pairs (65·5%), significantly more often than expected by chance. The probability of a fish winning was related to its relative metabolic rate (measured prior to introduction into the test arena); the higher the relative metabolic rate of a fish compared to its opponent, the greater its probability of being dominant. In the 36 pairs of fish where the low relative metabolic rate fish was the subordinate, its competitive ability was significantly correlated with how closely the two fish were matched in terms of their relative metabolic rates. The smaller the difference between the relative metabolic rates of the dominant high relative metabolic rate fish and subordinate low metabolic rate fish, the greater the competitive ability and feeding success of the low relative metabolic rate subordinate. However, no such relation was found in the 19 pairs of fish where the high relative metabolic rate fish was the subordinate. In these pairs, the competitive ability of the subordinate high relative metabolic rate fish was correlated with its size relative to its dyad partner. The larger the dominant low relative metabolic rate fish, the lower the competitive ability of the subordinate high relative metabolic rate fish.
Are long term negative effects from external tags underestimated? Fouling of an externally attached telemetry transmitter
Authors: Thorstad E. B. , ØKland F. , Heggberget T. G.
Published: April 2005

An externally attached radio transmitter and antenna on a farmed Atlantic salmon Salmo salar was overgrown with green algae, mussels, seaweed and Balanus sp. after the fish had stayed at sea from December 1997‐July 1998. This observation indicates that fouling may be an important factor, which is seldom considered when estimating negative effects from tags on the animals. Fouling increases the drag from the transmitter, and may affect the swimming speed, energy budget and behaviour of the fish. The effect is likely to be most pronounced in coastal waters.
Winter movements and habitat use of riverine brown trout, white sucker and common carp in relation to flooding and ice break‐up
Authors: Brown R. S. , Power G. , Beltaoa S.
Published: April 2005

Movement of radio‐tagged riverine brown trout Salmo trutta, white sucker Catostomus commersoni and common carp Cyprinus carpio in the Grand River, Ontario, was minimal during the winter except during periods of high water discharge or the break‐up of river ice. Ice break‐up and flooding occur when southern air masses penetrate northwards in winter and as air temperatures increase in spring. Both white suckers and common carp moved the longest distances, generally in a downstream direction, during flooding and ice break‐up. Brown trout moved less during these times. All three species had positive relationships between distance moved and water discharge. During periods of high water discharge and ice break‐up, white suckers and common carp used backwater habitats more and main channel habitats less than during periods of low water discharge. During high flows, brown trout tended to use runs more and pools less. The break‐up of river ice and accompanying flooding resulted in several fish being stranded on the floodplain. Backwater habitats appear to be important areas of refuge for riverine fishes during periods of flooding and ice break‐up.
Comparison between micro‐ and macro‐structure readings in the age estimations of Cape hake
Authors: Gordoa A. , Raventóas N. , Dealie F.
Published: April 2005

By counting otolith daily increments juvenile Cape hake Merluccius capensis were found to grow faster than European hake Merluccius merluccius. The mean frequency of translucent zones in juveniles 130–240 mm LT were higher (×3·2) than the annual frequency, although their mean duration was shorter (1 month) than a season. Comparison between micro‐ and macro‐structure readings showed that the latter tended to overestimate the age of juvenile hake, with 1 year old hake being overestimated by 18% in individuals of 160 and 210 mm LT.
Alloparental care between catfishes in Lake Tanganyika
Authors: Ochi H. , Onchiand T. , Yanagisawa Y.
Published: April 2005

A bagrid catfishAuchenoglanis occidentaliscared for its brood, deposited within an accumulation of shells and gravel in the centre of a large saucer‐like depression, for up to 2 weeks in Lake Tanganyika. Adults of another catfishDinotopterus cunningtoni(Clariidae) persistently came toA. occidentalisnests near days of host spawning. Eggs ofD. cunningtoniwere found in the host nests on the day and within 2 days of host spawning. During and for a few days after the end of host brooding, associate species' young of much older ages than the host brood were often found in the nests together with those of a similar age to the host young. Associate young were rarely found in nests before spawning and in unused nests. These findings suggested that this brood‐mixing has two origins: egg dumping by associate adults and voluntary intrusion of large associate young into host nests. Possible benefits to the associate species are to take advantage of nest preparation and parental behaviour of the host species and to feed on the host brood.
The stomach contents of Patagonian toothfish around South Georgia (South Atlantic)
Authors: Pilling G. M. , PURVES M. G. , Daw T. M. , Agnew D. A. , Xavier J. C.
Published: April 2005

The proportion of Patagonian toothfish Dissostichus eleginoides, caught around South Georgia in the south‐west Atlantic, with empty stomachs was much lower in fish caught in pots compared to longlines (28 and 91%, respectively, of examined individuals). It is hypothesized that pots caused reduced levels of stress on capture. Stomach content data examined from pot‐caught fish will probably therefore be more comprehensive than that from fish caught using longlines. A wide range of prey items was identified in the stomachs of D. eleginoides and stomach contents of individuals caught using the two fishing methods were significantly different. The most common prey item for D. eleginoides caught using pots was the decapod prawn Nauticaris sp., which was restricted in location and depth. However, prawns were not common in the stomachs of D. eleginoides caught from the same location using longlines. Stomach contents from the two fishing methods remained significantly different when Nauticaris sp. were eliminated from the assessment, although fishes then dominated the diet of D. eleginoides caught using either fishing gear. The study confirms that D. eleginoides is an opportunistic carnivore, and indicates that feeding habits depend on the local availability of food items, as well as factors such as depth and predator size. The potential ecological impacts of fishing for D. eleginoides on the South Atlantic ecosystem are discussed.
The spread of the eel swimbladder nematode Anguillicola crassus through the Erne system, Ireland
Authors: Evans D. W. , Matthews M. A. , McClintock C. A.
Published: April 2005

The spread of Anguillicola crassus was documented and showed an increase in both prevalence (9·9%) and mean intensity (6·7). Infected eels Anguilla anguilla were recorded 30 km downstream of the first recorded sites of infection. Migrating silver eels from commercial nets near the outlet of the Erne during October‐December 1999 were also infected. Continued spread of A. crassus through Ireland's major wild eel fisheries now appears likely.
Sex‐related variations of serum immunoglobulins during reproduction in gilthead sea bream and evidence for a transfer from the female to the eggs
Authors: Picchitti S. , Scapigliati G. , Fanelli M. , Barbato F. , Canese S. , Mastrolla L. , Mazzini M. , Abelli L.
Published: April 2005

A significant elevation of serum immunoglobulin (Ig) concentration occurred in female gilthead sea bream Sparus aurata during spawning. Furthermore, a progressive rise of serum Ig level was observed throughout the process of sexual inversion (from functional male to functional female), suggesting that the synthesis of Ig could be regulated by sex‐related factors (probably sexual hormones) involved in the process of oogenesis. The immunoglobulins of eggs were purified by affinity chromatography on protein A‐sepharose. SDS‐PAGE and Western blot analysis showed reactivity of the antiserum Pab1 with the Ig heavy and light chains, and some degradation products. This purification process yielded detectable amounts of Ig. The sex‐related increase of serum Ig during the reproductive period, and the detection of Ig in eggs suggest a transfer of Ig from the blood of the adult female.
The effect of light intensity and spectrum on the incidence of first feeding by larval haddock
Authors: Downing G. , Litvak M. K.
Published: April 2005

Under full–spectrum white light, feeding success of haddock Melanogrammus aeglefinus first feeding larvae, as measured both by proportion of larvae feeding and mean prey consumed, peaked at 1·7‐18 μmol s‐1 m‐2. Feeding was significantly reduced at lower and higher intensities. A similar result was observed for larvae feeding under blue (470 nm) light, with significantly greater feeding success at intermediate light intensity (1·8 μmol s‐1 m‐2). When different light qualities were compared, larvae had significantly greater feeding success when exposed to blue (470 nm) light than either full‐spectrum white or green (530 nm) light. Haddock larvae were capable of prey capture under all light treatments tested, indicating a necessary degree of adaptive flexibility in feeding response. The results are consistent with predisposition of haddock larvae to optimal feeding in a visual environment comparable with open ocean nursery grounds. Information on the impact of light on haddock first feeding can be incorporated into models of larval growth, survival, year‐class strength and recruitment, and assist in developing husbandry protocols to maximize larval survival in aquaculture.
Free and total cortisol levels in semelparous and iteroparous chinook salmon
Authors: Barry T. P. , Unwin M. J. , Malison J. A. , Quinn T. P.
Published: April 2005

Total cortisol, free cortisol and percent free cortisol were all significantly higher in semelparous male chinook salmon Oncorhynchus tshawytscha than in iteroparous and immature fish. The findings suggest that the regulation of both total and free cortisol concentrations may play key roles in mediating the post‐spawning death of semelparous Pacific salmon.
Interspecific trophic relationships among pelagic fish species underneath FADs
Authors: Deudero S.
Published: April 2005

Fortnightly experimental purse‐seine hauls at fish aggregation devices (FADs) and open water control sites, over a 2‐year period in oceanic waters o. the eastern coast of Majorca revealed that carangid, coryphaenid, serranid, balistid and centrolophid fishes caught there were mostly planktivores. Most of the species had a high food intake. The dominance of neustonic and holoplanktonic epipelagic prey could indicate a direct link between FADs, invertebrates (biofouling) and fish. Polyprion and Schedophilus were more generalist predators than the more specialized Naucrates and Trachurus spp. There was low variation in feeding intake and the types of prey categories important for each species. Naucrates, Coryphaena and Schedophilus characterized the autumn community under FADs, while Trachurus, Seriola and Balistes were present throughout the summer. There was little diet overlap among the species suggesting only limited competition for the food resources among Trachurus spp, Naucrates and Seriola, and among Seriola and Coryphaena.
Physical characteristics influencing the utilization of pools by brown trout in an afforested catchment in Southern Ireland
Authors: Elso J. I. , Giller P. S.
Published: April 2005

Seasonal and spatial variation in brown trout Salmo trutta L. abundance, density and biomass were studied in 29 pools of varying size in an afforested catchment together with the physical characteristics of those pools. A movement of 0+ trout towards the pools as the year progresses was detected. Water volume of the pool accounted for a significant amount of the variation in metrics across all seasons. Cover provided by overhanging vegetation also explained a significant amount of variation, especially during the summer. Water velocity, percentage of undercut bank and substrate composition had little explanatory power in the distribution of trout in the pools. In all seasons significant relationships between both fish biomass (g m−2) and fish number and water volume in the pool were found. However, in summer and autumn there was also a significant correlation between both fish density (fish m−2) and biomass and water volume in the pool described by a power function with a coefficient >1. These relationships were consistent across the subset of pools studied over a 2‐year period. Thus there was a proportionally greater number of fish in deeper pools than in the shallower ones in summer and autumn, suggesting that trout use the available habitat (i.e. the pool) as a three dimensional space in which an increase in the third dimension (depth) leads to a proportionally greater number of fish per unit area.
Oral administration of cholecystokinin receptor antagonists increase feed intake in rainbow trout
Authors: Gélineau A. , Boujard T.
Published: April 2005

Individual immature rainbow trout consumed 1–2% body weight per day, but significantly more (P < 0·001) when fed by hand than by demand feeder. When treated with CCK antagonists (L 364, 718; 100 μg kg−1 on day 12 or SR 27, 897; 50 μg kg−1 on day 16), the fish ate significantly more than their mean daily intake on the other days of the experiment. This increase in feed intake was affected by the feeding technique: hand‐fed fish increased by 70–80% their feed intake while in demand‐fed fish the increase was significantly less (50–60%). However, the increase in feed intake observed on days 12 and 16 was identical for both drugs used.
An alternative to validation of otolith microincrementation
Authors: Joyeux J‐C. , Aliaume C. , Zerbi A.
Published: April 2005

In absence of otolith marking and laboratory rearing, a statistical alternative to validate the daily rhythm of sagittal microincrementation in Puerto Rican juvenile snook Centropomus undecimalis is described. Albeit the technique may be essentially limited to tropical immature fishes, it offers interesting possibilities in post‐validating ageing previously based on assumption of daily frequency of material deposition.
Four members of the Sox gene family in channel catfish
Authors: Zhou R. , Zhang Q. , Tiersch T. R. , Cooper R. K.
Published: April 2005

The homologous sequences of human or mouse SOX1, SOX4 and SOX11, and one novel Sox gene (named Ccf‐SoxN) were identified in the genome of channel catfish Ictalurus punctatus. Identification of these genes is a potential step in understanding development regulations including sex determination in channel catfish.
Early ontogeny of coal grunter from hormone‐induced spawnings and laboratory‐reared embryos and larvae
Authors: Close P. G. , Barlow C. G. , Rodgers L. J.
Published: April 2005

Spawning of coal grunter Hephaestus carbo was successfully induced using doses of human chorionic gonadotrophin (hCG) between 500 and 3000 IU kg (body weight)−1. Water hardened eggs are telolecithal, amber in colour, spherical, transparent, demersal and slightly adhesive with a single large oil droplet and perivitelline space 47% of total egg volume. Cleavage begins 10–15 min after fertilization. Epiboly begins 6h after fertilization and continues for 4 h. Invagination of the neural tube is apparent 11·5 h after fertilization, followed by progressive organogenesis up to hatching 60–80 h after fertilization. An invagination in the yolk, consistent in shape, position and time of appearance among embryos spawned from numerous brood stock pairs, was visible in all fertilized eggs between neurulation (11‐5 h) and early organogenesis (20 h). The functional significance of this yolk invagination is unknown. Newly‐hatched larvae (4·2 mm LT) are elongate and possess well developed eyes, a functional mouth, and a large yolk sac. Yolk is fully resorbed and first feeding occurs at 6 days posthatching. The sequence of fin formation is caudal, second dorsal and anal, first dorsal, pectoral and pelvic. The prefiexion larval stage lasts for c.8 days and flexion of the notochord is complete within a further 8–9 days. Squamation commences at 30 days posthatching and transition to the juvenile life stage is complete by 35–40 days posthatching.
Relationships between otolith microstructure, otolith growth, somatic growth and ontogenetic transitions in two cohorts of windowpane
Authors: Neuman M. J. , Witting D. A. , Able K. W.
Published: April 2005

Otolith increments in larval and juvenile windowpane Scophthalmus aquosus can provide an estimate of daily age for spring‐spawned individuals held under summer conditions. Otolith increments for spring‐ and autumn‐spawned individuals occurred at intervals >1 day under winter conditions. A significant decrease in the slope of the linear relationship between otolith size and somatic size at 40 mm LS coincided with significant habitat, morphological and behavioural transitions. In smaller, field‐captured windowpane belonging to spring‐ and autumn‐spawned cohorts, the formation of accessory growth centres coincided with a transitional settlement period and the completion of eye migration (c. 8–20 mm LS). Back‐calculated growth rate estimates for spring‐spawned windowpane were significantly faster than those for autumn‐spawned windowpane and these differences could produce differential rates of survival for the two cohorts during the first year of life.
Density, aggregation, and body size of northern pikeminnow preying on juvenile salmonids in a large river
Authors: Petersen J. H.
Published: April 2005

Predation by northern pikeminnow Ptychocheilus oregonensis on juvenile salmonids Oncorhynchus spp. occurred probably during brief feeding bouts since diets were either dominated by salmonids (>80% by weight), or contained other prey types and few salmonids (<5%). In samples where salmonids had been consumed, large rather than small predators were more likely to have captured salmonids. Transects with higher catch‐per‐unit of effort of predators also had higher incidences of salmonids in predator guts. Predators in two of three reservoir areas were distributed more contagiously if they had preyed recently on salmonids. Spatial and temporal patchiness of salmonid prey may be generating differences in local density, aggregation, and body size of their predators in this large river.
Comparison of compensatory growth responses of juvenile three‐spined stickleback and minnow following similar food deprivation protocols
Authors: Zhu X. , Cui Y. , Ali M. , Wootton R. J.
Published: April 2005

The compensatory growth responses of individual juveniles of two co‐ existing species were compared after identical periods of starvation to determine inter‐specific similarities and differences. The carnivorous stickleback Gasterosteus aculeatus was compared with the omnivorous minnow Phoxinus phoxinus. Both species experienced 1 or 2 weeks of starvation before being re‐fed ad libitum. The two species differed in their response to the starvation periods, with minnows showing a lower weight‐specific loss. Both species showed compensatory responses in appetite, growth and to a lesser extent, growth efficiency. Minnows wholly compensated for 1 and 2 weeks of starvation. At the end of the experiment, sticklebacks starved for 2 weeks were still showing a compensatory response and had not achieved full compensation. The compensatory responses of the sticklebacks showed a lag of a week before developing in the re‐feeding phase, whereas the response of the minnows was immediate. Analysis of lipid and dry matter concentrations suggested that the compensatory response restored reserve lipids while also bringing the fish back to the growth trajectory of continuously fed fish.
Species and hybrid richness in spined loaches of the genus Cobitis (Teleostei: Cobitidae), with a checklist of European forms and suggestions for conservation
Authors: Bohlen J. , Ráb P.
Published: April 2005

Until recently, one widespread species of the genus Cobitis was thought to be present in Europe, the common spined loach Cobitis taenia. Recent studies have shown that the diversity of spined loaches is considerably higher due to (1) presence of several species as well as C. taenia and (2) presence of hybrid biotypes, living together with species. Here knowledge about distribution and diversity of spined loaches in Europe is summarized by combining original with published data. In Southern Europe, a number of distinct species occur allopatrically, while in Central and Eastern Europe a few species have wide distribution areas. Hybrid biotypes were found exclusively in Central and Eastern Europe. They were not restricted to the contact areas between the parental species, but occur in almost the entire area. In total, 15 hybrid biotypes with different genomic compositions were recorded. In the most diverse complex, four hybrid biotypes were associated with one species. In general, a syntopic occurrence of different species of Cobitis can be considered as exceptional, while the association of species with hybrid biotypes is the rule in Central and Eastern Europe. The composition of complexes seems to be most strongly influenced by the kind of associated species and by local history. Implications for conservation are (1) not to disturb the natural patterns of diversity, (2) to consider the known richness in legislation, and (3) to consider the evolutionary significance of hybrid biotypes.