bluuebunny/crossref_metadata_2025 huggingface dataset:
Rare British marine fishes‐identification and conservation
Authors: Swaby S. E. , Potts G. W.
Published: January 2006

Methods of recording and categorizing rare British marine fishes and their habitats are described. Information is stored on a database designed for maximum flexibility, cross‐referencing, multiple word search and key word search facilities. Examples are given and discussed in relation to species and habitat protection.
Colonization, larval survival and epidemiology of the nematode Anguillicola crassus, parasitic in the eel, Anguilla anguilla, in Britain
Authors: Kennedy C. R. , Fitch D. J.
Published: January 2006

In late 1987, immature Anguillicola crassus were reported for the first time in Britain from eels from two river systems. By late 1988, gravid adults were present in a number of rivers in the east of England in two discrete centres of distribution: one in East Anglia correlated with the route taken by lorries exporting eels to the continent, and one in the R. Thames correlated with the import of eels to London. The parasite was firmly established in the R. Trent, where prevalence levels reached 100% in some places.

Laboratory investigations showed that adult parasites and their eggs remained viable even after infected eels had been maintained for 4 weeks in 100% sea water. Hatching of eggs declined with increasing salinity, but was not totally inhibited by sea water. Survival and infectivity of freeliving second stage larvae were maximal in natural fresh water (95% survival for 4 months, and 50% still infective to copepod intermediate hosts after 70 days), but declined in alkaline water and with increased salinity. Nevertheless, in 100% sea water, 50% of larvae were still infective after 8 days. Specificity to the intermediate host was low, and eels of all sizes could be infected.

These characteristics, plus a high reproductive potential, give the parasite exceptional colonization potential and ability, enabling it to survive natural movements of eels from catchment to catchment and to increase rapidly within a new locality. The ability of free‐living larvae to adhere to the substratum and survive in sea water enables them to survive in eel‐transport lorries from which they will not readily be removed by flushing, the normal cleansing procedure. It is concluded that there were two separate introductions of the parasite to Britain; via the eel import trade through London, and, totally unexpectedly, via the eel export trade in lorries traversing East Anglia. The parasite is now firmly established in Britain and will continue to spread by natural movements of eels but especially by human‐assisted movements of infected eels for stocking and market. This latter practice is recognized as a major factor in introducing and disseminating fish parasites.
Diel cycle inHoplosternum littorale(Teleostei): evidence for synchronization of locomotor, air breathing and feeding activity by circadian alternation of light and dark
Authors: Boujard T. , Keith P. , Luquet P.
Published: January 2006

Diel cycles of voluntary food intake, locomotor activity and air breathing were studied inHoplosternum littorale(Hancock, 1828), a siluriform fish of the Callichtyidae family living in marshes in northern South America. The study was carried out with six groups of 30 fish each reared in 200‐1 tanks equipped with demand‐feeders and maintained under artificial light‐dark conditions (13.5 L/10.5 D). Feed demand started at dusk and increased throughout the night with a peak between 02.00 and 05.00 hours, during which 3‐h period the fish ate 40% of their total daily ration. There was a marked peak in air breathing and locomotion at dusk, followed by an increased feed intake. When the light‐dark cycle was advanced by 9 h the observed phenomena were the same, so it is assumed that the light‐dark alternation is the synchronizer. In starved fish, locomotor activity and air breathing were increased in the light phase.
Ovarian atresia and sex ratio imbalance in white sucker,Catostomus commersoni
Authors: Trippel E. A. , Harvey H. H.
Published: January 2006

In a small north‐temperate lake, 53–56% of post‐spawning, female white suckers spanning a wide range of ages showed ovarian atresia in 1981 and 1987. Comparison of ovarian atresia frequencies and adult sex ratios in nine white sucker populations indicated that this spawning disorder may have been due to a paucity of males at spawning. Adult female:male sex ratio in the King Lake population was 2.82:1 in 1981 and 2.73:1 in 1987, compared with 0.91:1 to 1.75:1 in populations that exhibited lower resorption frequencies (0–7.1%). Removal of 29% of the King Lake male suckers in 1988 elevated the female: male sex ratio to 3.5:1 and frequency of ovarian atresia rose to 75%. Unspawned ova were almost completely resorbed 3 months after the spring spawning period. Post‐spawning mortality was not different between spent and resorbing females. The somatic condition of resorbing and spent females did not differ. There was no evidence that atresia interfered with gamete development subsequently. The sex ratio imbalance present in King Lake was not a function of population density.
Seasonal changes in energy and the energy cost of spawning in Gulf of Alaska Pacific cod
Authors: Smith R. L. , Paul A. J. , Paul J. M.
Published: January 2006

In the Gulf of Alaska, adult Pacific cod exhibited an annual cycle of condition, gonad index and liver index in which maximum values occurred in ripe fish in March and minima in July. About 30–31 % of prespawning stored energy was expended during the spawning effort. The energy associated with spawning derived from liver (24% and 18%), somatic tissue (22% and 33%) and gonad (53% and 48%) for females and males, respectively. Liver index and gonad index at the time of sampling were directly related in females, but in males gonad index was best related to liver index 1–3 months earlier.

The Pacific cod is very similar to the Atlantic cod in terms of energy cycling, maximum gonad sizes, energy expended during spawning and gonadal contribution to energy expenditure. However, in Pacific cod, somatic tissue contributes markedly to energy expended during reproduction. The Pacific cod cod differs from the walleye pollock with respect to gonad index (13% and 20%ν. 20% and 8% for females and males, respectively), spawning weight loss (25%ν. 38%), liver energy loss during spawning (71%ν. 55%) and energy cost of spawning.
Protandric hermaphrodite peculiarities in Amphiprion frenatus Brevoort (Teleostei, Pomacentridae)
Authors: Brusle‐Sicard S. , Reinboth R.
Published: January 2006

Electron microscopy of the male phase of the ovotestis of Amphiprion frenatus, a protandric hermaphrodite, showed no connective tissue between male and female areas and, as the basal lamina was lacking both along the seminiferous tubules and round the previtellogenic oocytes, the male and female germ cells were only separated by their respective surrounding somatic cells (Sertoli and follicle cells). Besides previtellogenic oocytes, oocytes in meiotic prophase and very small (young) previtellogenic oocytes, were detected in the ovarian part, as spermatogenesis proceeded, revealing oogenetic activity. Degeneration of some previtellogenic oocytes and their follicle cells was discernible.
Diet and prey selection of six species of tuna baitfish in three coral reef lagoons in the Solomon Islands
Authors: Milton D. A. , Blaber S. J. M. , Rawlinson N. J. F.
Published: January 2006

The diets and prey selection of six species of tuna baitfish (the engraulids Stolephorus devisi and S. heterolobus, three dussumierids of genus Spratelloides, and the apogonid Archamiazosterophora. were examined at two heavily fished and one unfished site in the Solomon Islands. All species ate almost exclusively nektonic zooplankton, especially crustaceans. Calanoid copepods were the most importantpreyofallspeciesexcept A. zosterophora, whichateagreater biomassoflarvalfish. Baitfishcould be divided into two groups according to prey taxa: the apogonid A. zosterophora and the engraulids S. devisi and S. heterolobus ate similar prey in similar proportions; the three dussumierid species (Spratelloides) ate smaller zooplankton and a greater proportion of calanoids than the other species.

The size of prey eaten differed greatly between baitfish species. A. zosterophora ate larger prey than other species. The two Stolephorus species ate similar‐size prey, which were larger than the prey of the three species of Spratelloides. Among the Spratelloides, S. delicatulus ate smaller prey than the other two species. All species differed in the size of calanoids, carids and brachyurans they ate. In all cases, prey differed more by the minimum dimension (width) than by volume. There were significant relationships between fish length and prey width and volume, except for Archamia. However, in terms ofvolume, the prey of Stolephorus increased with fish size at a much greater rate than in Spratelloides species.

Baitfish diets were compared to the zooplankton available. Prey selection by the three Spratelloides species and two Sfolephorus species was density‐dependent for all common prey types, although Stolephorus positively selected hyperiid amphipods and brachyurans. Archamia showed strong negative selection for calanoids and selected larger zooplankters, including fish larvae and carids, avoiding smaller, more common, prey.

Overall baitfish density and zooplankton density did not correlate at either of the heavily fished sites. Nor were there consistent differences for any species in diet or changes in prey selection between the heavily fished and unfished sites. This suggests that, in these lagoons, commercial baitfish catches are not directly influenced by the composition or density of prey.
Residence time of the sea louse, Lepeophtheirus salmonis K., on Atlantic salmon, Salmo salar L., after immersion in fresh water
Authors: McLean P. H. , Smith G. W. , Wilson M. J.
Published: January 2006

Returning adult salmon caught at the mouth of the River Dee, Aberdeenshire, were transferred to tanks in the laboratory. For fish placed in fresh water, sea lice remained attached for up to 6 days, though most lice were lost in the first 48 hours. Few lice were lost from salmon maintained in sea water. The experiments were conducted in water within a temperature range of 12·8 to 16° C, equivalent to summer river temperatures in the Aberdeenshire Dee.
Gonad maturation and spawning times of Siganus sutor off the Keny a coast: evidence for definite spawning seasons in atropical fish
Authors: Ntiba M. J. , Jaccarini V.
Published: January 2006

The gonad maturation cycle of Siganus sutor (Valenciennes, 1835) (Osteichthyes‐Siganidae) is described for both males and females using macroscopic criteria for the testes and both macroscopic and microscopic ones for staging the ovaries. Siganus suror has two major spawning seasons: one in January/February and the other in May/June. The presence of these seasons is established by (a) the temporal variations in the condition factor and in the relative weight of the gonads, (b) the progression of peaks of maturity stages with seasonal occurrence of spent fish in the samples, and (c) the seasonal appearance ofjuveniles. This is a significant result for a tropical marine fish.
Biology of parasite populations: population dynamics of bothriocephalids (Cestoda‐Pseudophyllidea) in teleostean fish
Authors: Robert F. , Boy V. , Gabrion C.
Published: January 2006

Relationships between sympatric populations of four species of Cestoda belonging to the genus Bothriocephalus (B. barbarus. B. gregarius, B. funiculus and B. scorpii) and populations of their respective hosts Scophthalmus rhombus, Pserra maxima, Ciliata mustela and Myoxocephalus scorpius were investigated. The parasites were overdispersed within their host populations. The mean intensities of B. burbarus were 1.59 (s.d.=0.83) in the Mediterranean (Gulf of Lions) and 1.25 (s.d.=0.53) in the Atlantic (coasts of Brittany). The mean intensities of B. gregarius were 62.3 (s.d.=49.7) in the Mediterranean and 14.06 (s.d.=18.48) in the Atlantic, compared to 1.78 (s.d.=0.3) for B. funiculus and 21.6 (s.d.=17.3) for B. scorpii.

The distribution of prevalence of B. gregarius corresponded to a lognormal distribution while those of B. barbatus and B. fwticulus corresponded to negative binomials. No differences in infection could be related to host sex. The parasitization of B. gregariusdepended on host size. In brill, infection by E. barbatus was independent of host size and remained stable after the fish reached 180mm in length. Parasitization of turbot by E. gregarius was lower in young fish (≤110–150 mm) and increased with the host size. Compared to the Atlantic populations of B. gregarius and B. barbatus, the Mediterranean populations were more frequently and intensively infected. The differences in the population dynamics of B. gregarius and B. barbarus would appear to depend on whether or not the life cycle involves a paratenic host.
Vascularization and related distribution of leucocytes in carp, Cyprinus carpio L., head kidney
Authors: Imagawa T. , Hashimoto Y. , Kon Y. , Sugimura M.
Published: January 2006

The distribution of lymphoid cells in the carp head kidney was investigated in relation to the vascular system. Blood vessels in the head kidney were histologically identified into arteries, sinusoids and two types of veins: renal veins and portal, which were distinguished by India ink injection into the caudal vein. By histological and histoplanimetrical observations it was found that the head kidney contained a number of lymphoid cells, which mainly aggregate around the connections between the portal veins and sinusoids, and that the cellular density of the aggregations was higher than in the thymus.

Pigment‐containing cell clusters were also observed around these connections. This arrangement of the blood vessels suggests that it is one of the structures able to trap foreign materials, and the occurrence of the lymphoid clusters around the portal veins is a phylogenetic sign of the morphological division between granulopoietic and lymphatic tissues in the carp head kidney.
The status of the barbel, Barbus barbus (L.) (Teleostei, Cyprinidae), in the United Kingdom
Authors: Wheeler Alwyne , Jordan D. R.
Published: January 2006

The barbel was originally a fish with a relatively restricted range in the British Isles. However, despite the general environmental degradation of many British rivers, and in contrast with some native freshwater fishes, the barbel is now more widely distributed than it was a century ago. It may even be more abundant numerically.
Compensatory sea growth of male Atlantic salmon, Salmo salar L., which previously mature as parr
Authors: Skilbrei O. T.
Published: January 2006

The proportion of mature male parr in 11 families of Atlantic salmon, Sulrno sulur, reared under similar conditions in fresh water varied from 0–43%. The mature males were smaller than their siblings in December as 1 + and in late March. After individual tagging and transfer to a sea cage in early April. the previously mature males grew faster than previously immature salmon during the next 6 months. This compensatory growth resulted in almost equal size between the two groups. The results are discussed in relation to the different life strategies of salmon.
Life history tactics of darters (Percidae: Etheostomatiini) and their relationship with body size, reproductive behaviour, latitude and rarity
Authors: Paine M. D.
Published: January 2006

Patterns of covariation of life history traits of darters in the genus Etheostoma are reviewed. The primary pattern is associated with body size. Large darters grow faster, mature at a larger size, produce bigger clutches, and have longer reproductive and life spans, and shorter spawning seasons, than do small darters. When the effects of size are removed statistically, the dominant secondary pattern matched the r‐K continuum from fast‐growing, short‐lived, primarily semelparous species with many small ova and a high reproductive effort (r‐species) to slow‐growing, long‐lived, iteroparous species with few large ova and a low reproductive effort (K‐species). Variation in life history traits is also influenced by reproductive behaviour, latitude, and rarity (as measured by geographic range). There are significant differences in the primary and secondary life history patterns among reproductive guilds. Latitude and rarity are not correlated with these primary and secondary patterns. Instead, they account for variation of tertiary patterns. Rare species may not match the reproductive performance of more common and widely distributed species. Future studies of life history traits in darters should focus on species whose reproductive behaviour differs from that of the species reviewed in this study, and on the demographic characteristics of rare or declining populations.
A new method for karyological studies in teleost fishes
Authors: Cucchi C. , Baruffaldi A.
Published: January 2006

A simple method employing CoCl2, is described which has application in the rapid preparation of fish chromosomes for research and teaching. The benefits of this method include low initial skill level, relatively inexpensive equipment and supplies, and the production of a high number of metaphase spreads.
Comparing fish catches taken with gill nets of different combinations of mesh sizes
Authors: Jensen J. W.
Published: January 2006

Based on net selectivity curves and the pooled relative efficiency of combinations of mesh sizes, models for comparing gill‐net catches taken with different combinations of mesh sizes are presented for perch, burbot and, in more detail, for salmonids. The models enable comparison of length frequencies and the numbers of fish within any length range caught with an acceptable net efficiency. A standard for comparing salmonids is proposed.
Growth and nutrient utilization by 0 + and 1 + triploid rainbow trout, Oncorhynchus my kiss
Authors: Oliva‐Teles A. , Kaushik S. J.
Published: January 2006

Growth performance, protein and energy utilization in triploid rainbow trout juveniles of two yearclasses, 0 + and 1 +, were compared to diploid control groups. Growth rate, food conversion and protein efficiency ratios of triploid rainbow trout did not differ (0 + juveniles) or were slightly lower (1 + juveniles) than the diploid control. Proximate body composition was also not affected by ploidy.

Apparent digestibility coefficients (ADC) ofprotein and ofenergy, oxygen uptake, and ammonia excretion rates were not different between the two groups. Nitrogen and energy balance studies showed that digestive and metabolic utilization of the diets did not differ in triploid and diploid rainbow trout juveniles.
Terrestrial locomotion in the climbing perch, Anabas testudineus (Bloch) (Anabantidea, Pisces)
Authors: Davenport J. , Matin A. K. M. Abdul
Published: January 2006

Climbing perches use the tail for forward propulsion when on land. The spiny gill covers are used to obtain purchase on the substratum. Unusually amongst teleosts, the opercular and subopercular bone are not bound strongly together into a single operculum. Instead they are joined only by a thin, flexible membrane, so that the fish has two sections of the gill cover hinged separately; the opercular on the suspensorium and the subopercular on the rearmost part of the lower jaw. The gill covers open very widely and the subopercular rotates ventrally as well as laterally. Two modes of locomotion are employed. Usually Anabus adopts a near‐upright posture and alternately drives the left and right spiny suboperculars into the substratum, using the tail to vault over the subopercular (which acts in the manner of a short vaulting pole). During vigorous movement the fish may leave the substratum altogether during the vault. Fatigued fish, or fish which have fallen during climbing, move on their sides, using the tail for propulsion and a single spiny opercular which is repeatedly driven into the substratum. Maximum speeds observed on land corresponded to 1.8 body lengths S−1. No evidence of involvement of the pelvic fins in locomotion was obtained; the pectorals seemed only to help in tilting the head from side to side and did not contribute significantly to forward propulsion. On mud and tree bark the fish were laterally unstable, often resting on their sides. Grassy substrata provided support and permitted a more upright posture.

Slope climbing ability was restricted to 25° when climbing tree bark and 30° when climbing grass. Coupled with lateral instability these observations disqualify the species from any tree‐climbing capacity. Anabas can climb vertical obstacles of at least half body length in height by pushing the head against the obstacle, using the spiny gill covers for purchase until one or other subopercular hooks over the top of the barrier. The subopercular is then used as a fulcrum for an upwards vault to clear the obstacle.
Early development of the digestive tract of cod larvae, Gadus morhua L., during start‐feeding and starvation
Authors: Kjørsvik E. , van der Meeren T. , Kryvi H. , Arnfinnson J. , Kvenseth P. G.
Published: January 2006

Cod larvae, Gadus morhua L., were reared in the laboratory and released to a large marine enclosure 4 to 5 days after hatching (6–8° C). The development of the digestive system was studied until day 24 after hatching. Morphological investigations of the jaw apparatus and the digestive tract showed that the larvae are able to absorb ingested food well before exhaustion of the yolk sac. The foregut, and especially the midgut, were particularly active in lipid absorption, and the hindgut was characterized by pinocytotic activity. Duhng the first days of feeding, no distinct prey organisms were observed in the gut, and signs of food absorption in the epithelial cells of the gut were sparse.A distinct red fluorescence, restricted to the hindgut, was observed from day 11 to day 19. On the basis of changes in absorptive pattern in the gut we suggest that changes in digestive and absorptive abilities, as well as in nutritional needs, take place around days 15–17 after hatching.

In starved larvae, signs of degeneration of the gut tissue were first visible in the foregut. By day 9 after hatching, microvilli was degenerated to such an extent that the ability to absorb food must have been severely restricted. If larvae are starved longer than this, they will probably not survive.
Gastric emptying in cod, Gadus morhua L.: emptying and retention of indigestible solids
Authors: dos Santos J. , Jobling M.
Published: January 2006

Particles 2 mm or smaller may be passed relatively easily through the pylorus of the cod, Gadus morhua L., but, under some conditions, 5 mm particles are held in the stomach for prolonged periods. The emptying of indigestible particles appears to be impaired by the consumption of additional meals, and prolonged retention of these particles may occur in fish fed multiple meals. The findings agree in general with those reported for mammals and the results are discussed in relation to mechanisms thought to control gastric motor activity patterns.
Histology of the stomach of Tilapia nilotica (Linnaeus, 1758) from the River Nile
Authors: Osman A. H. K. , Caceci T.
Published: January 2006

The histology of the stomach of Tilapia nilotica (Linnaeus) collected from the R. Nile (Ismailia fork in Egypt) was examined using light microscopy and scanning electron microscopy. The study revealed that the gastric wall is composed of several tunicae: mucosa, submucosa, muscularis and serosa. The tunica mucosa is thrown up into a number of high longitudinal folds projecting into a lumen which is stellate in cross‐section when empty. The mucosal surface has a mosaic appearance due to the hexagonal borders of the surface epithelial cells. The latter cells are characterized by the presence of a juxtanuclear vacuole and a PAS‐positive brush border made of microvilli. Gastric pits (foveolae) are present as invaginations of the mucosal surface. The foveolar epithelium secretes neutral and acid mucins. Simple, straight, tubular unbranched gastric glands occupy most of the depth of the mucosa, and are lined with a single type of cell which has eosinophilic granules. Gut‐associated lymphoid tissue (mainly lymphocytes, macrophages and eosinophilic granulocytes) is concentrated on the sides of the lamina muscularis mucosa and especially in the cores of the mucosal folds. The muscular coat consists of two or three layers entirely made up of smooth muscle cells.
Critical swimming velocities of juvenile sockeye salmon and kokanee, the anadromous and non‐anadromous forms of Oncorhynchus nerka (Walbaum)
Authors: Taylor E. B. , Foote C. J.
Published: January 2006

In streams tributary to the North Pacific, anadromous sockeye salmon and non‐anadromous kokanee, Oncorhynchus nerka (Walbaum), occasionally spawn sympatrically and male kokanee may act as 'sneaks’to spawn with the larger female sockeye. Despite this interbreeding, sockeye and kokanee exhibit persistent biochemical genetic differences at several enzyme loci. Genetic differences between forms may be maintained by selection against‘hybrids’due to the different life histories of sockeye and kokanee; sockeye make extensive smolt, oceanic, and spawning migrations while kokanee reside permanently in fresh water. We tested the sustained swimming abilities of juvenile sockeye, kokanee, and sockeye (female) × kokanee (male) hybrids to see if hybrids were inferior to sockeye in a trait that is probably under stronger selection in an anadromous life history. Sockeye had significantly greater mean critical swimming velocities (Ucrit) than kokanee of the same size raised under identical conditions (8.3 v. 7.3 body lengths s−1 respectively). When tested 1 month later the mean Ucrit of sockeye was only marginally greater than that for sockeye × kokanee hybrids (both c. 6.6 body lengths s−1). Sockeye swimming performance was also less variable than that of either kokanee or hybrids.

Sockeye tended to have slimmer bodies and longer caudal regions than kokanee or sockeye × kokanee hybrids of the same size. Sockeye also had significantly more vertebrae than kokanee and hybrids, while hybrids had more vertebrae than kokanee. These morphological differences may have contributed to the differences in swimming performance. We concluded: (i) that juvenile sockeye and kokanee have diverged with respect to sustained swimming performance and that reduced performance by kokanee may be due to relaxed selection for sustained swimming performance associated with their non‐anadromous life history, (ii) that sockeye × kokanee hybrids appear to have modestly lower swimming capabilities than pure sockeye, and (iii) if the variability in swimming performance is associated with differences in survival in nature, then such differences may promote divergence between sympatric sockeye and kokanee.
Myxosporea parasites in roach, Rutilus rutilus (Linnaeus), from four lakes in central Finland
Authors: Brummer‐Korvenkontio H. , Tellervo Valtonen E. , Pugachev O. N.
Published: January 2006

Ten myxosporean species belonging to three families were found in roach, Rutilus rutilus (Linnaeus), obtained in 1985 and 1986 from four lakes in central Finland which are connected to each other, but differ in water quality. One of the lakes is polluted by paper and pulp mill effluent, two are eutrophic and one is oligotrophic and still in its natural state. Eight species were found in all the lakes. The most common species were Myxidium rhodei Léger, 1905, Myxobolus muelleri Bütschli, 1882 and Myxobolus pseudodispar Gorbunova, 1936 with prevalences varying between 66–80, 16–31 and 32–59%, respectively, in the four lakes. The largest difference in myxosporean prevalence between lakes was found in the case of M. pseudodispar infection, which was highly significantly lower in the polluted lake. The locations of the myxosporean species in the tissues of the fish were found to be species‐specific. M. rhodei and M. muelleri being prevalent in the kidney and M. pseudodispar in the muscles.

No clear seasonal variation was found but a tendency for a decrease in infection with increasing age was recorded in the case of M. rhodei and M. pseudodispar.
The respiratory burst of rainbow trout, Oncorhynchus mykiss (Walbaum), phagocytes is modulated by sympathetic neurotransmitters and the‘neuro’peptide ACTH
Authors: Bayne C. J. , Levy S.
Published: January 2006

The phagocytic leukocytes of teleosts, like those of many animal groups, are capable of converting molecular oxygen to a series of highly reactive oxygen intermediates. These constitute part of the cytotoxic defences of the animal. Reactive oxygen intermediates produced in vitro by rainbow trout, Oncorhynchus mykiss (Walbaum), pronephric myeloid cells have been detected by means of luminol‐enhanced chemiluminescence, and by the reduction of cytochrome c in the presence and absence of exogenous superoxide dismutase and catalase. A panel of potential biological response modifiers, when added individually to cell suspensions, showed that the catecholamine receptor agonists phenylephrine and isoproterenol differentially modulate the respiratory burst. Receptor antagonists yohimbine, phentolamine and prazosin showed that the effects were receptor‐mediated. Adrenocorticotropin (ACTH) enhanced the apparent respiratory burst in both assays. Pathways of neuroimmunological regulation, therefore, include non‐lymphoid cells as targets of classical neurotransmitters and a neurohormone.
Uptake of vitellogenin into oocytes during early vitellogenic development in the rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: Tyler C. R. , Sumpter J. P. , Campbell P. M.
Published: January 2006

Uptake of 3H‐vitellogenin (3H‐VTG) into oocytes of various sizes was investigated during early vitellogenic development in the rainbow trout, Oncorhynchus mykiss (Walbaum). Females were injected with 3H‐VTG and uptake into oocytes of different sizes (<0.4,0.4–0.59, 0.6–0.79, 0.8–0.99 and 1.0 1.2 mm in diameter) measured. Oocytes measuring less than 0.6 mm in diameter appeared unable to sequester VTG and were therefore considered pre‐vitellogenic. Oocytes measuring 0.6 mm or more all sequestered VTG. The larger the oocyte, the more 3H‐VTG it sequestered, even when uptake was expressed per unit surface area. The latter observation could be due to an increase in the number of VTG receptors per unit surface area, an increase in the rate of turnover of the VTG receptor, greater access of VTG to the receptors as oocytes grow, or a combination of any of these factors. The data suggest that the ability to sequester VTG is developmentally regulated.
Gonadotropin release following oral delivery of luteinizing hormone‐releasing hormone and its superactive analogue (des‐Gly10 [D‐Ala6] LHRH ethylamide) to 17β‐oestradiol‐primed coho salmon, Oncorhynchus kisutch (Walbaum)
Authors: McLean E. , Parker D. B. , Warby C. M. , Sherwood N. M. , Donaldson E. M.
Published: January 2006

The permeability of the coho salmon, Oncorhynchus kisutch (Walbaum), gut to orally administered LHRH and LHRHa (des‐Gly10 [D‐Ala6] LHRH ethylamide) was examined over a 360 min time‐course. Both forms of LHRH were detected in the blood plasma of treated fish within 30 min of delivery. Retained biological activity of the absorbed LHRH was also assessed. Oral delivery of LHRH or LHRHa to 17β‐oestradiol‐primed coho resulted in a significant (P < 0.01) release of gonadotropin (GtH) when compared to saline intubated, 17β‐oestradiol‐primed animals. The dose response of 17β‐oestradiol‐primed coho salmon to orally delivered LHRHa revealed that maximal GtH release occurred at doses between 2.0 and 20 μg LHRHa per g body weight.
Fish species associations in riffle habitat of streams of varying size and acidity in New Brunswick and Nova Scotia
Authors: Peterson R. H. , Gale D.
Published: January 2006

Factors related to stream size and alkalinity were most influential in determining fish species associations in three catchments of New Brunswick (NB) and Nova Scotia (NS) Canada, as determined by discriminant function analysis of TWINSPAN stream site classification.

In the circumneutral Saint Croix (NB) catchment, the creek chub, Semotilus atromaculatus (Mitchill), brook trout, Salvelinus fontinalis (Mitchill), blacknose dace, Rhinichthys atratulus (Hermann), Atlantic salmon, Salmo salar Linnaeus, eel, Anguilla rostrata (Lesueur) and fallfish. Semotilus corporalis (Mitchill) dominated stream sites of progressively greater discharge and higher median mid‐summer temperature. In the acidic Gold (NS) system, the brook trout, Atlantic salmon, and eel exhibited a distribution pattern in relation to stream size and temperature similar to that for the Saint Croix, with the eel relatively more abundant in the Gold at large stream sites. The creek chub was excluded from the smallest tributaries by low pH. The ranges of blacknose dace and fallfish do not extend to southwestern Nova Scotia. In the Medway (NS) system (slightly more acidic than the Gold), the relative abundance of Atlantic salmon is reduced, and that of eel increased as compared with the Gold and Saint Croix systems. The lower limiting mid‐summer pH levels for creek chub, salmon, brook trout, and eel are 5.2, 5.0, 4.7 and <4.5 respectively.
Food intake and growth in the Moses perch, Lutjanus russelli (Bleeker), with reference to predation on penaeid prawns
Authors: Smith R. L. , Salini J. P. , Blaber S. J. M.
Published: January 2006

Juvenile Moses perch were fed various rations of penaeid prawn and pilchard foods at 26.4 and 28.7° C to elucidate feeding–growth relationships. Maintenance rations amounted to 5.0 and 3.8% of body weight per day (BW day–1) on prawn and pilchard diets, respectively, at 26.4° C and 4.5% BW day 1 for prawn at 28.7° C. This apparent reduction in maintenance ration at higher temperature is probably due to reduction in activity levels. Starvation weight loss, an indicator of resting metabolic rate, increased with temperature and exhibited a Q10 of 2.0 to 2.4.

Fish fed ad libitum once or twice per day at 26.4° C grew at 1.1 % BW day–1 and ingested about 9% of their BW day–1. At 28.7° C fish ingested about 8% of their BW day–1 and grew 1 .0% BW day–1. These growth rates are comparable to those of similar sized lutjanids in the wild. Since prawns comprise 64% of the diet of Moses perch in northern Australia, this level of consumption would require about 6% BW day–1 of prawns. The relevance of these findings to the assessment of predator impact on prawns in Australian estuaries is discussed.
Survival, growth and feeding of vendace, Coregonus albula (L.), larvae in net enclosures
Authors: Karjalainen J.
Published: January 2006

Vendace, Coregonus albula (L.), larvae reared in net enclosures anchored in the littoral zone of Lake Ylä‐Enonvesi, eastern Finland, were observed for a period of 44 days in order to determine the effects of density on mortality, growth and feeding of the larvae. The ratio of newly‐hatched fish to their food was regulated by controlling the number of fish stocked into the enclosures. Prey animals were expected to move freely in and out of the enclosures. The effect of nylon mesh (500 μm) on the penetration of zooplankters into the enclosures was negligible. The influence of possible starvation was determined by analysing the growth of the larvae, their Fulton condition factor, the instantaneous amount of food ingested, and the food composition in their guts. All these indicators were inversely correlated with larval density. Vendace larvae were found to be resistant to mortality from direct starvation. At all densities the survival rate was over 60%. At the time of complete yolk absorption, there was no increase in mortality.
The fish fauna of the Jordan reservoir, one of the oldest man‐made lakes in central Europe
Authors: Kubecka J. , Bohm M.
Published: January 2006

The Jordan reservoir, Czechoslovakia, was constructed in 1492 and the last full drainage and fish removal was in 1830. In this ‘mature’ fish community of 20 species (plus three hybrids), the roach, Rutilus rutilus (L.) (1446 fish ha–1) and beam, Abramis brama (L.) (1074 fish ha–1) dominated the fish stock (total of all species = 3628 fish ha–1). Predatory species made a small contribution to the total (maximum 7.7%, obligatory predators 2%). The contribution (12%) by perch, Perca fluviatilis L., was also low, and its numbers in successive age‐groups showed a steady decrease. The high variability and time‐synchronization in the year‐class strengths of the principal cyprinid species may indicate unstable environmental conditions or intra‐community cycles. The growth rates of non‐predatory species were low. There was a high fishing rate on predatory species but there was little impact by fishery management on the whole ‘mature’ community. Intensive eutrophication from both communal waters and agriculture probably caused the high biomass level (all species) and the low abundance of zander, Stizostedion lucioperca (L.).
Changes in plasma protein patterns in smolting Atlantic salmon, Salmo salar L., are not dependent on changed growth rates
Authors: Rourke A. W. , Saunders R. L. , Harmon P. R.
Published: January 2006

Juvenile Atlantic salmon, Salmo salar L., were raised under simulated natural photoperiod (SNP) and constant light (CL). SNP fish displayed typical characteristics of smolts in the spring including changes in colouration, elevated gill Na+/K+ ATPase activity and ability to pass a seawater challenge. CL fish grew at rates comparable to SNP fish, but did not demonstrate any of these molt characteristics.

Electrophoretic analyses of plasma proteins from both groups of fish revealed that SNP fish displayed reproducible qualitative changes in protein patterns from February to May with May patterns being the most complex. CL fish displayed patterns similar to SNP fish. The timing of the appearance of patterns was influenced by photoperiod as indicated by the fact that CL fish had a progression of pattern changes retarded by at least one month relative to SNP fish. The changes in plasma protein patterns in smolting Atlantic salmon were not dependent on changed growth rates.
The host specificity of Gyrodactylus salaris Malmberg (Platyhelminthes, Monogenea): susceptibility of Oncovhynchus mykiss (Walbaum) under experimental conditions
Authors: Bakke T. A. , Jansen P. A. , Kennedy C. R.
Published: January 2006

An experimental epidemiological approach was chosen to study the survival and infection dynamics of Gyrodactylus salaris on juvenile rainbow trout, Oncorhynchus mykiss, in the laboratory. A marked heterogeneity in the host stock was apparent. The rainbow trout could be divided into three groups on the basis of parasite survival and infection pattern on individually isolated fish: (1) hosts receptive to initial parasite attachment, but unreceptive to parasite establishment and reproduction; (2) hosts moderately susceptible to parasite establishment and reproduction, but which, after a period of restricted parasite population growth, responded, recovered and eliminated the parasites; and (3) hosts very susceptible to parasite infection and reproduction, but which, after a period of significant parasite population growth, responded, recovered and eliminated the parasites. These different patterns are considered to reflect genetic differences between host individuals. Parasite aggregation was also shown to be an important factor in the outcome of the host‐parasite association. The parasites were finally eliminated on the individually isolated hosts, but not on hosts maintained in batches and so host population size and immigration of fresh. previously unexposed, hosts appeared to be important for growth and maintenance of the parasite population. The parasite was not found to cause host mortality. Rainbow trout was a suitable host for G. salaris, capable of transmitting the parasite to new localities as a consequence of stocking programmes or migratory behaviour.
Population structure of the fifteen‐spined stickleback, Spinachia spinachia (L.)
Authors: Kaiser M. J. , Croy M. I.
Published: January 2006

Scottish and Welsh populations of the 15‐spined stickleback, Spinachia spinachia (L.), had similar growth rates. Scottish fish were generally smaller than Welsh fish. Most fish are annual, but some females may delay reproduction until the following year.
The nomenclature of the Pacific herring, Clupea pallasü Valenciennes, 1847
Authors: Rass Th , Wheeler Alwyne
Published: January 2006

Confusion over the nomenclature of the Pacific herring is shown to have stemmed from the comparison of it with White Sea herring which was mistakenly assumed to be conspecific with Atlantic herring.
Factors influencing otolith increment formation in Japanese eel,Anguilla japonica T. & S., elvers
Authors: Umezawa A. , Tsukamoto K.
Published: January 2006

To determine the effect of environmental factors on otolith increment deposition in Japanese eel, Anguilla japonicaT. & S., a total of 337 elvers with a tetracycline time mark in the otolith were reared for 50 days under various experimental temperatures (12, 19 and 25°C), feeding rations (fed and unfed) and salinities (one‐third sea water of I 2k and fresh water). Fish were sequentially sampled after 5. 15, 30 and 50 days and their sagittal otolith increments were observed. Under fed conditions at 19 and 25°C, daily increment deposition was observed throughout the 50‐day period. In unfed groups and/or at 12°C, the rates of increment deposition were reduced sharply after the fifth day and no clear increments were added. No difference was obtained in increment deposition rates between one‐third sea water and fresh water groups. Increment deposition rate was independent of otolith and body size.
Carbohydrate metabolism during embryonic and larval development of Odonthestes humensis(De Buen, 1953) (Pisces—Atherinidae)
Authors: Santos E. A. , Vinagre A. S.
Published: January 2006

Changes in glucose and glycogen concentrations during embryonic and larval development of Odonthestes humensis (De Buen, 1953) (Pisces—Atherinidae) were followed.

Glycogen decreased immediately after fertilization but remained constant throughout the embryonic period, suggesting that although present glycogenolisis may not be the most important energetic pathway during this period. Glucose levels only show a significant increase on the fifth day of development coincident with the beginning of heart activity.

In fed larvae glycogen utilization increases during development, resulting in an increase in glucose concentration. Such a pattern does not occur in starved animals, where glycogen and glucose are present respectively at high and low concentrations similar to embryos. The change of pattern seems to be associated with the first larval feeding.
Diet of spiny dogfish, Squalus acanthias Linnaeus, on the east coast, South Island, New Zealand
Authors: Hanchet S.
Published: January 2006

Stomach content data from 7283 spiny dogfish, Squalus ucunthius Linnaeus, from east coast South Island of New Zealand are presented. The major dietary components based on occurrence were 60% crustaceans and 15% fish. The principal food items were the post‐larval phase of the squat lobster, Munida greguria Fabricius (30%), and the euphausiid, Nyctiphanes australis Sars (20%). Commercial fish species contributed to less than 5% of the diet. Diet of dogfish varied with dogfish size and sex. Compared to northern hemisphere studies, spiny dogfish in this study area had (1) a high proportion of crustaceans in their diet, (2) a relatively low percentage of empty stomachs, (3) a relatively high incidence of cannibalism.
Age determination in Pomatoschistus mi nut us (Pallas) and Pomatoschistus microps (Kreyer) (Pisces: Gobiidae) from the upper Tagus estuary, Portugal
Authors: Moreira F. , Costa J. L. , Almeida P. R. , Assis C. , Costa M. J.
Published: January 2006

The use of scale inspection as a means of age‐determination in Pomatoschistus microps and Pomatoschistus minutus in the Tagus estuary is confirmed, but annulus formation pattern is different from that described for P. microps in the area of the British Isles (Miller, 1975). In Britain, two annuli are laid down on the scales each year, but in the Tagus, only one annulus is formed. One possible reason for this difference is the fact that in the Tagus the peak breeding season and the lowest water temperatures coincide. Therefore, the two causes of annulus formation coexist at the same time of year.

Population structure in both species is dominated by the 0‐group, which appears earlier (April/May) than reported for other areas. Maximum age seems not to exceed 26 months in P. microps and 32 months in P. minutus.
Seasonal population dynamics of Paraquimpevia tenevvima (Linstow) (Nematoda) in the European eel Anguilla anguilla (Linnaeus) in three localities of southwest England
Authors: Nie P. , Kennedy C. R.
Published: January 2006

Seasonal population dynamics of Puraquzmperia tenerrima (Linstow) in the European eel Anguillu anguillu (Linnaeus) have been investigated in three localities in Devon, southwest England. The nematode is common and exhibits very similar seasonal patterns in changes of prevalence and abundance in the three localities. The population increases over winter through to late spring or early summer as the recruitment of the new generation occurs throughout this period. Reproduction of the nematode starts in spring. A sharp decrease of prevalence and abundance accompanies or follows reproduction, and infection levels are very low in autumn and early winter. The dispersion pattern of the nematode varies with the infection levels from over‐dispersion in spring and early summer to almost random dispersion in autumn and winter. It is suggested that P. tenerrimu is a common specific parasite of eels, especially in small streams or rivers and that insect larvae or species of crustaceans might serve as intermediate hosts for the nematode.
New biochemical genetic markers in the brown trout (Salmo trutta L.)
Authors: Jorde P. E. , Gitt A. , Ryman N.
Published: January 2006

Three ‘new’ polymorphic loci in the brown trout (Salmo trutta L.) was detected using starch gel electrophoresis. Evidence for simple Mendelian inheritance at all three loci are presented.
Influence of oral administration of 3,5,3′‐triiodo‐thyronine on growth, digestion, food conversion and metabolism in the underyearling red sea bream, Chrysophrys major (Temminck & Schlegel)
Authors: Woo N. Y. S. , Chung A. S. B. , Ng T. B.
Published: January 2006

The effect of inclusion of 3,5,3′‐triiodo‐∼‐thyronine (T3) in the diet was examined in underyearling red sea bream Chrysophrys major (Temminck & Schlegel). The treatment brought about increases in growth rate, appetite, food conversion efficiency and activities of intestinal enzymes including leucine nitroanilidase, alkaline phosphatase, α‐glutamyltransferas, α‐amylase and disaccharidase. There were no changes in the muscle content of water, protein, lipid and glycogen. Liver glycogen content was elevated, as well as activities of the hepatic enzymes glycogen phosphory‐lase, glycogen synthetase, glutamate‐pyruvate transaminase, fructose‐ 1, 6‐diphosphatase and glucose‐6‐phosphatase. The serum concentrations of total protein, albumin, globulin, α‐amino acids. glucose, ammonia and calcium were increased by the treatment whereas the serum concentrations of free fatty acids, cholesterol and triglyceride remained unaltered. The results suggest that in the red sea bream T, stimulated protein and carbohydrate but not lipid metabolism and that the hormone promoted growth by improving appetite, digestion and absorption.