bluuebunny/crossref_metadata_2025 huggingface dataset:
Population stability over a ten‐year period in the short‐lived fish Liparis liparis (L.)
Authors: Henderson P. A. , Holmes R. H. A.
Published: August 2010

A ten‐year study of the population dynamics of the sea‐snail, Liparis lipuris, in the Bristol Channel, England is reported. This small fish which only lives for 1 year undertakes a regular seasonal migration from birth in marine waters into the estuary from which it retreats during the winter to return to the spawning grounds by early spring. At Hinkley Point, Somerset (salinity 22–3O%), abundance has been shown to be negatively correlated with water temperature presumably because of the avoidance of warmer inshore waters during mild winters. When the temperature effect is removed from the data the peak winter abundance of the population was found to have a coefficient of variation of only 27%. For a population which only comprises of age group individuals, this shows a remarkable stability. No statistically significant relationship was found between the abundance of sea‐snail and either their predators or prey. However, there were indications of a negative relationship with the abundance of whiting, Merlangius merlangus, which was the most abundant predator. We conclude that the population of a short‐lived marine fish living within a physically variable marine environment can be constrained within tight limits. Further. sea‐snail reproductive success has been independent of variation in local physical conditions.
Opsonizing properties of natural antibodies of rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: Michel C. , Gonzalez R. , Avrameas S.
Published: August 2010

In order to confirm previous observations in which a protective effect of rainbow trout natural antibodies against furunculosis was suspected, phagocytosis studies wereconducted in vitro, using combinations of rainbow trout sera with high or low levels of natural antibodies and active or inactivated complement as opsonizing factors. Opsonization was observed in all the cases where complement was present, and to a lesser degree with sera containing only natural antibodies. The results confirm the prime importance of the complement system and provide additional evidence for a possible role of natural antibodies in antimicrobial defences.
Sperm production and steroidogenesis in testes of the common carp, Cyprinus carpio L., at different stages of maturation
Authors: Koldras M. , Bieniarz K. , Kime D. E.
Published: August 2010

Testes from carp, Cyprinus carpio L., at five different maturational stages from immature through to spermiation and regression were incubated with or without addition of carp hypophysial homogenate (chh) for 8 or 20 h. Concentrations of steroids and spermatozoa were measured in the medium and the residual tissue examined histologically. There was an increase in the area of the germinal cysts containing spermatozoa, the percentage of the testis which they occupied and in the production of spermatozoa as the gonadosomatic index (GSI) increased, but this was unaffected either by incubation or by pretreatment with chh. The major steroid in plasma and in in vitro testicular cultures from all of the maturing fish captured in winter was 1 I‐ketotestosterone. The production rate of this steroid in virro was unaffected by GSI, while plasma levels tended to increase with GSI. 17.20β‐Dihydroxy‐4‐pregnen‐3‐one was detectable in significant amounts in only a few spermiating fish in summer, but was stimulated more in incubations with chh in maturing winter than in summer spermiating or post‐spawning fish. 17,20a‐Dihydroxy‐4‐pregnen‐3‐one was not detectable in incubations, but plasma concentrations tended to increase towards spermiation and were positively correlated with the size of the cyst. After spawning, fish had low plasma steroid levels and failed to respond in vitro to pituitary extract, indicating a testicular post‐spawning refractoriness.
Environmental variables affecting the sexual segregation of great white sharksCarcharodon carchariasat the Neptune Islands South Australia
Authors: Robbins R. L.
Published: August 2010

The seasonal temporal sexual segregation of white sharksCarcharodon carcharias, at the Neptune Islands, South Australia, is described in relation to environmental variables. A significant sexual segregation was found at this site with sex ratios strongly favouring males overall. Males were more prevalent than females in all months in a 3 year sampling period, aside from April and May. There was a significant difference between the sexes in terms of mean daily numbers over the months of the study. It was also observed that sexual segregation fluctuated for unknown reasons on a temporal scale. Predictive models for estimating male and female numbers based on a series of abiotic factors were generated. Sea surface temperature, tidal height, tidal range, moon phase, cloud cover, underwater visibility and swell height were related to daily sightings of male and female white sharks to determine the influence of these variables on sexual segregation. Visibility and sea surface temperature affected male numbers, however, visibility did not affect sexual segregation. Tidal height was significantly different between males and females. Sea surface temperature also appeared to be related to sexual segregation in this species. Females were present when temperatures ranged from 15·7 to 18·1° C whereas males were observed at temperatures ranging from 14·3 to 17·8° C, with a peak in sightings in September, when sea surface temperatures were at their lowest. Since parturition is thought to occur in spring or summer, it is suggested that females are absent at this time and only return during prime feeding periods or times at which temperatures are elevated in order to increase developmental growth rates of their young. The significantly lower temperatures in 2003 may explain the absence of females in this year. Hypotheses related to temperature regulation in this species are put forward to explain the sexual segregation observed.
Comparative morphology and histology of the ovaries of the spined loach Cobitis taenia L. and natural allopolyploids of Cobitis (Cobitidae)
Authors: Juchno D. , Boroń A. , Gołaszewski J.
Published: August 2010

The maturity of ovaries, gonado‐somatic index and size of oocytes in particular developmental stages during the reproductive period of spined loach Cobitis taenia and allotriploid and allotetraploid Cobitis were examined. The ploidy levels of all the loaches were determined according to karyotypes. All the investigated females spawned multiple times and the spawning period was from the end of May (water temperature c. 18·5° C) to mid‐ or the end of July. Some of the triploids had a longer spawning period which lasted until the end of August. Each female could lay several portions of eggs which differed in size and number during the spawning season. The relative proportion of oocytes of each stage in the ovaries during the reproductive period changed. The sizes of oocytes at the particular stages of triploids were statistically significantly larger than oocytes in the respective stages in C. taenia (diploid). The sizes of the oocytes (each stage) of C. taenia from both populations were not significantly different.
Evidence of stenotopy and anthropogenic influence on carbon source for two major riverine fishes of the Lake Victoria watershed
Authors: Ojwang W. Oweke , Kaufman L. , Soule E. , Asila A. A.
Published: August 2010

Stable isotope analysis was used to investigate the migratory status and to determine the relative contribution of allochthonous and autochthonous sources of carbon for the major riverine fish species (Barbus altianalis and Labeo victorianus) in rivers draining the Kenyan side of Lake Victoria. The two fish species derived carbon from both C4 and C3 plant sources, although L. victorianus exhibited less enriched isotopic carbon values. Fish samples from stations under direct influence of effluents from sugar factories exhibited enriched δ13C signals. Assuming that this reflects carbon sourcing from riparian C4 plants, it suggests that carbon from terrestrial sources can be a major energy source in some rivers. This heavy carbon enrichment associated with sugar factories was spatially restricted and occurred in all seasons, implying that sub‐populations of the two fish species are non‐migratory. The large migratory populations of these two species, for which Lake Victoria was once famous, may be no more.
Foraging behaviour and functional morphology of two scale‐eating cichlids from Lake Tanganyika
Authors: Takahashi R. , Moriwaki T. , Hori M.
Published: August 2010

The foraging behaviours of two Tanganyikan scale‐eating cichlids, Perissodus straeleni and Perissodus microlepis, were observed in laboratory. Video analyses of their feeding behaviours showed the distinct differences in scale‐eating action between the two species. Perissodus straeleni presses and shifts its mouth laterally along the body of the prey as the prey attempts to break free. In contrast, P. microlepis quickly rotates its body, with both jaws pressed tightly against the flank of the prey. Scanning electron microscopy of tooth shapes confirmed that dental morphology clearly differs between the two species: the teeth of P. straeleni are laminar and leaf‐shaped with sharp edges along the lateral sides, whereas P. microlepis has thick, broad‐based teeth with spine‐like points in the upper corners. In addition, inspection of tooth condition in wild‐caught fishes showed that the ratio of wearing teeth was significantly higher in P. straeleni than in P. microlepis. These results indicate that the functional morphology of the teeth plays an important role in their scale‐eating actions; in P. straeleni, the sharp edges of the teeth appear to function as blades for scraping while shifting the mouth laterally along the body of the prey, whereas the spine‐like projections on the teeth of P. microlepis appear to effectively catch scales while pressing and rotating the mouth, simultaneously wrenching off scales. These results clearly demonstrate that the different scale‐eating behaviours of the two species are closely associated with the functional diversification of their jaw teeth.
10 000 years later: evolution of body shape in Haida Gwaii three‐spined stickleback
Authors: Spoljaric M. A. , Reimchen T. E.
Published: August 2010

The body shape of 1303 adult male three‐spined sticklebackGasterosteus aculeatusfrom 118 populations on Haida Gwaii archipelago off the mid‐coast of British Columbia was investigated using discriminant function analysis on partial warp scores generated from 12 homologous landmarks on a digital image of each fish. Results demonstrated geographical differences in adult body shape that could be predicted by both abiotic and biotic factors of the habitat. Populations with derived shape (CV1−), including thick peduncles, posterior and closely spaced dorsal spines, anterior pelvis, small dorsal and anal fins, were found in small, shallow, stained ponds, and populations with less derived shape (CV1+), with small narrow peduncles, anterior and widely spaced dorsal spines, posterior pelvis, large dorsal and anal fins were found in large, deep, clear lakes. This relationship was replicated between geographic regions; divergent mtDNA haplotypes in lowland populations; between predation regimes throughout the archipelago, and in each geographical region and between predation regimes in lowland populations monomorphic for the Euro and North American mtDNA haplotype. There were large‐bodied populations with derived shape (CV2−), including small heads and shallow elongate bodies in open water habitats of low productivity, and populations with smaller size and less derived shape (CV2+), with large heads and deeper bodies in higher productivity, structurally complex habitats. This relationship was replicated between geographic regions, and partially between divergent mtDNA haplotypes in lowland populations. Field tests for phenotypic plasticity of body shape suggest that <10% of the total variation in body shape among populations throughout the archipelago can be attributed to plasticity.
Age determination and backcalculation of pike length through use of the metapterygoid bone
Authors: Sharma C. M. , Borgstrøm R.
Published: August 2010

The validity of the metapterygoid bone of pikeEsox luciusfor use in age determination and backcalculation of total length (LT) was evaluated by using tagged pike recaptured after 4 months to 3 years. A regression equation for the relationship between pikeLTand metapterygoid length was estimated, and no significant deviations between the backcalculated and expectedLTat tagging were found for recaptured pike. The results confirm that 1) the checks are formed annually and 2) no false checks appeared on the metapterygoids of pike.
Does increased abundance of sea lice influence survival of wild Atlantic salmon post‐smolt?
Authors: Hvidsten N. A. , Finstad B. , Kroglund F. , Johnsen B. O. , Strand R. , Arnekleiv J. V. , Bjørn P. A.
Published: August 2010

A synthesis of results from two projects was assessed to analyse possible influence of sea lice Lepeophtheirus salmonis on marine Atlantic salmon Salmo salar survival. During the years 1992–2004, trawling for wild migrating post‐smolts was performed in Trondheimsfjord, a fjord in which no Atlantic salmon aquaculture activity is permitted. Prevalence and intensity of sea lice infections on migrating wild post‐smolts differed between years. A correlation analysis between 1 sea‐winter (SW) Atlantic salmon catch statistics from the River Orkla (a Trondheimsfjord river) and sea lice infections on the migrating smolts in the Trondheimsfjord was not significant. Up to 2% reduction in adult returns due to sea‐lice infection was expected. In addition, experimental releases from 1996 to 1998 with individually tagged groups of hatchery‐reared Atlantic salmon smolts given protection against sea‐lice infection was performed. Higher recaptures of adult Atlantic salmon from 1998 treated smolts compared to the control group may correspond to high abundance of sea lice found on the wild smolt, and may indicate influence on post‐smolt mortality. These studies indicate that post‐smolt mortality in Trondheimsfjord is marginally influenced by sea lice infection; however, the methods for assessing wild smolt mortality might be insufficient. Higher infections of sea lice farther out in the fjord may indicate more loss in Atlantic salmon returns in some years.
Air breathing minimizes post‐exercise lactate load in the tropical Pacific tarpon, Megalops cyprinoides Broussonet 1782 but oxygen debt is repaid by aquatic breathing
Authors: Wells R. M. G. , Baldwin J. , Seymour R. S. , Christian K. A. , Farrell A. P.
Published: August 2010

Swimming in a flume at reduced water pO2 resulted in muscle and blood lactate levels in Pacific tarpon Megalops cyprinoides that were significantly higher when fish did not have access to air. Blood glucose and haematological variables were unchanged throughout the regimes of exercise at two swimming speeds and hypoxia. Strenuous exercise with bouts of burst swimming, however, resulted in both high blood lactate and glucose, and perturbed haematological status with elevated haemoglobin and reduced mean cell‐haemoglobin concentration. Post‐exercise recovery was achieved through aquatic breathing rather than by air breathing. The air‐breathing organ in Pacific tarpon therefore prolonged aerobic activity, but gill breathing was used to repay oxygen debt.
Estimating survival of the shortfin makoIsurus oxyrinchus(Rafinesque) in the north‐west Atlantic from tag‐recapture data
Authors: Wood A. D. , Collie J. S. , Kohler N. E.
Published: August 2010

Survival was estimated for shortfin makoIsurus oxyrinchusin the north‐west Atlantic from tag‐recapture data. The data used in this study were collected by the National Marine Fisheries Service Cooperative Shark Tagging Programme from 1962 to 2003. In total, 6309 shortfin mako sharks were tagged, of which 730 were recaptured. The high recapture rate of 11·6% for this species provided adequate recapture data to carry out survival analyses. Estimates of survival were generated with the computer software MARK, which provided a means for estimating parameters from tagged animals when they were recaptured. The results of several models are presented with various combinations of constant and time‐specific survival and recovery rates. A parametric bootstrap and the median variance inflation factor () approach were used to test the fit of the general model to the data. The estimatedindicated a very good model fit. The models with time invariant survival rate had the most support from the data and no group or time period effects were found. Recovery rate (f) appeared to increase from 0·043 in the early years to 0·056 in the later years. The nominal survival rate of 0·59 year−1was adjusted with an estimated tag‐shedding rate of 0·26 year−1to generate a final corrected annual survival estimate of 0·79 with a 95% CI of 0·71–0·87.
Energy expenditures during spawning by chum salmon Oncorhynchus keta (Walbaum) in British Columbia
Authors: McVeigh B. R. , Healey M. C. , Wolfe F.
Published: August 2010

Physiological telemetry and proximate tissue analyses were used to assess energy expended by chum salmon Oncorhynchus keta on various behaviours during spawning in Kanaka Creek, British Columbia, Canada, and results were compared with published data on Fraser River sockeye salmon Oncorhynchus nerka, the only other species for which both types of measurements have been taken. Chum salmon arrived at the spawning grounds with body energy densities of 4·84 MJ kg−1 in males and 4·62 MJ kg−1 in females, lower than most sockeye salmon populations, and died with energy densities of c. 4 MJ kg−1, similar to that observed in sockeye salmon and other salmonids. Moisture levels generally increased in body tissues over the spawning life, particularly in female gonads, and lipid levels decreased. Declines in protein observed over the spawning life of other Pacific salmon Oncorhynchus sp. were less evident in Kanaka Creek chum salmon. Holding behaviour constituted the dominant component of the activity schedule and energy budget of both sexes. After holding, the most expensive behaviours were nest digging in females and aggressive displays in males. Dominant males expended the most energy on behaviours each day, as indexed by oxygen consumption (3600 mgO2 kg−1), while satellite males expended nearly as much (3504 mgO2 kg−1) but females expended considerably less (2327 mgO2 kg−1). Kanaka chum salmon engaged more frequently in energetically expensive reproductive behaviours than Stuart River sockeye salmon.
Monoamine oxidase activity in kidney and heart ofPiaractus mesopotamicus(Holmberg)
Authors: Salles C. M. C. , Salles J. B. , Cunha Bastos V. L. F. , Dias R. A. , Cunha Bastos J.
Published: August 2010

The values of Michaelis–Menten constant (KM) and maximum velocity (VMAX) for kidney and heart monoamine oxidase (MAO) from pacuPiaractus mesopotamicuswere determined. The mean ±s.e. KMvalues were 17·28 ± 2·27 μM for kidney and 15·38 ± 1·86 μM for heart. MAO activities were 111·60 ± 3·25 and 15·12 ± 0·30 nmols min−1g−1of wet tissue for kidney and heart, respectively. In addition, MAO inhibitory studies in these two tissues indicate that this enzyme may be a different isoform of MAO.
Mate choice, sexual coercion and gene flow in guppy populations
Authors: Magellan K. , Magurran A. E.
Published: August 2010

The role of behaviour in gene flow in Trinidadian guppies Poecilia reticulata was assessed using fish from an upstream and downstream pair of populations that differ in predation regime. High‐predation (downstream) females preferred males from the corresponding low‐predation population, but high‐predation males achieved greater reproductive success under competition. This suggests that post‐copulatory as well as pre‐copulatory events are important in determining rates of gene flow.
Settlement of gilthead sea bream Sparus aurata L. in a southern Irish Sea coastal habitat
Authors: Craig G. , Paynter D. , Coscia I. , Mariani S.
Published: August 2010

For the first time, early juvenile stages of gilthead sea bream Sparus aurata were consistently collected in a brackish estuarine area in the southern Irish Sea over a period of 4 months. This finding, in connection with other recent evidence, raises the possibility that S. aurata may currently spawn, or at least successfully settle, in more northern locations than previously known.
Reproductive biology of the threatened golden galaxias Galaxias auratus Johnston and the influence of lake hydrology
Authors: Hardie S. A , White R. W. G , Barmuta L. A
Published: August 2010

Golden galaxias Galaxias auratus (31–235 mm fork length, LF) were collected monthly from littoral habitats in Lakes Crescent and Sorell, Tasmania, Australia, between July 2000 and December 2002. Spawning habitats were identified and monitored in both lakes, and surveyed in Lake Crescent. Trends in gonado‐somatic indices and reproductive stages of development indicated that gonad development in both sexes begins in midsummer and peaks in late autumn to early winter. Males mature at smaller sizes (50% at 52 mm LF) than females (50% at 76 mm LF), larger individuals are predominately females (95% of fish ≥138 mm LF), and overall male to female ratios are female biased (c. 1:2). Spawning occurs late autumn to early spring (water temperatures = 1·4–9·7° C) with peaks in spawning activity in winter (mean water temperatures <5° C). Demersal adhesive eggs (c. 1·5 mm diameter) were found on cobble substrata (c. 20–250 mm diameter) in littoral areas (c. 0·2–0·6 m deep) and fecundity of fish 71–181 mm LF ranged from 619 to 14 478 eggs. The rate of change in water level over the 20 days prior to monthly sampling was important in explaining the occurrence of spent fish and this accounted for temporal differences in spawning between the populations. Lake hydrology influences the reproductive cycle of G. auratus by possibly providing a stimulus for spawning and it controls the availability of spawning habitat in Lake Crescent. Seasonal hydrological cycles (i.e. rises during late autumn to winter) and a minimum water level of 802·20 m Australian Height Datum in Lake Crescent during autumn (above which littoral areas of cobble substratum are inundated) are critical to G. auratus populations.
Iteroparity in complex mating systems of steelhead Oncorhynchus mykiss (Walbaum)
Authors: Narum S. R. , Hatch D. , Talbot A. J. , Moran P. , Powell M. S.
Published: August 2010

This study investigated diverse reproductive types in complex mating systems of steelhead Oncorhynchus mykiss. Postspawned steelhead (kelts) were sampled during attempted downstream migration over Lower Granite Dam on the Snake River, U.S.A. Multilocus microsatellite genotypes (14 loci) were used to assign unknown origin, kelt individuals to upstream populations of origin. Results indicated that iteroparity is a life‐history trait that remains in several tributaries of the Snake River basin despite strong selection against downstream adult passage because of hydroelectric dams. The largest populations of steelhead in the Snake River, however, were only weakly represented (Clearwater River = 7·5% and Salmon River = 9·4%, respectively) in the kelt steelhead mixture relative to the Grande Ronde River (18·2%), Imnaha River (17·4%), Pahsimeroi Hatchery (25·2%) and Asotin Creek (22·2%). A lack of correlation between population escapement size and kelt proportions (P > 0·05) suggests that iteroparity was not uniformly expressed across populations, but was significantly negatively correlated with body size (P < 0·05). Iteroparity may be a valuable source of genetic variability and a conservation priority, especially in years with poor recruitment or in recently bottlenecked populations.
Lifetime consequences of variable 0 year group length in riverine populations of chubLeuciscus cephalus(L.)
Authors: Bolland J. D. , Britton J. R. , Cowx I. G.
Published: August 2010

The fork length (LF) of individual chubLeuciscus cephalusin English riverine populations at the end of their first growth season varied considerably, ranging from <25 to >70 mm. This had a significant influence on the subsequent growth of individuals over their lifetime. Chub of smallLFat age 1 year generally produced smaller annual growth increments throughout life than those of longerLFat age 1 year, although they had the potential to attain greater ultimateLF. This variability inLFat age 1 year resulted, at least in part, from multiple spawning events over a protracted period, that caused variation in the growing seasons for 0 year group chub of the same year class. Since the adult population contained individuals that only attainedLFof <25 mm at the end of their first growing season, it is possible thatLFat age 1 year may not be such a major precursor to strong chub recruitment as previously thought.
Is fecundity in plaice (Pleuronectes platessa L.) down‐regulated in response to reduced food intake during autumn?
Authors: Kennedy J. , Witthames P. R. , Nash R. D. M. , Fox C. J.
Published: August 2010

The effect of controlling food intake during the autumn, which is the time of late vitellogenesis, on fecundity, atresia and follicle and ovary growth was examined for plaice Pleuronectes platessa. Eighteen fish were kept in individual pens and either fed on a high or low ration diet. Fish which increased in whole body condition exhibited an increase in carcass condition which means that when food intake is sufficient to maintain whole body condition some resources are used as storage. Follicle growth rate was positively correlated with change in Fulton’s condition and total atresia was negatively correlated with change in Fulton’s condition. Thus, the rate of vitellogenesis was dependent on the availability of an exogenous food source. Fecundity at the end of the experiment was positively correlated with mass and total length. Food intake had no effect on relative fecundity; however, fish which had a lower food intake lost mass and had a greater intensity of atresia, lowering their absolute fecundity. One fish in a very low condition at the start of the experiment skipped spawning and one fish exhibited a decrease in average follicle diameter during the experiment which is hypothesized to be a prelude to mass atresia.
Size and fecundity variation in populations of Poecilia vivipara Block & Schneider (Teleostei; Poeciliidae) inhabiting an environmental gradient
Authors: Gomes‐Jr J. L. , Monteiro L. R.
Published: August 2010

The reproductive variables [female size (geometric centroid size), fecundity and offspring size (longest diameter of the embryo)] of the livebearer Poecilia vivipara in the quaternary lagoons of northern Rio de Janeiro State varied significantly among sites and were partially associated within and among sites. Mean female size was directly related to salinity. Fecundity (number of offspring) was directly related to female size both within and among sites. The female size × fecundity relationship, however, was not constant among sites. Offspring size was partially and directly associated with female size and salinity. The relationship between fecundity and female size was positively related with fecundity, suggesting a non‐linear relationship of these variables when the total sample was considered. The results suggest that life‐history differences among sites were more related to different predation regimes than to simple effects of plasticity caused by increased growth in saltwater environments.
On estimating diversity in species‐rich fish assemblages: an example with coral‐reef fishes of eastern Indonesia
Authors: Tokeshi M. , Arakaki S.
Published: August 2010

A new procedure for estimating fish species richness in open or semi‐open habitats is presented with unpublished data on the coral‐reef fish assemblages of Raja Ampat, eastern Indonesia, known as the centre of marine biodiversity in the western Pacific.
Aspects of reproduction and diet of the Australian endemic skate Dipturus polyommata (Ogilby) (Elasmobranchii: Rajidae), by‐catch of a commercial prawn trawl fishery
Authors: Kyne P. M. , Courtney A. J. , Bennett M. B.
Published: August 2010

The Australian endemic skate Dipturus polyommata collected from by‐catch of a benthic prawn fishery off southern Queensland was examined to provide information on reproduction and diet. Morphological relationships of total length (LT) to disc width and LT to mass were estimated. Size at birth was estimated at c. 100–110 mm and size at first feeding at c. 105–110 mm LT. Size at 50% maturity (LT50 and 95% CI) was 321 (305–332) and 300 (285–306) mm LT for females and males, respectively. Size at first maturity corresponded to 87·7% of observed maximum size in females (366 mm LT) and 87·5% in males (343 mm LT). Two females, representing 18·2% of mature females sampled in the austral winter were each carrying two egg cases. Descriptions of egg cases are given. Diet described by the index of relative importance as a percentage (%IRI) was predominantly crustacean based with carid shrimps (53·64%) and penaeoid prawns (23·30%) the most significant prey groups. Teleosts (11·72%), gammarid amphipods (5·31%) and mysids (4·72%) were also important to the diet of the species, while a further six prey groups made only a minor contribution to diet (1·31%). An ontogenetic change was evident between the diets of immature and mature skates. Immature animals fed more extensively on carids and amphipods and mature animals on penaeoids, teleosts and mysids.
Reduced condition factor of two native fish species coincident with invasion of non‐native Asian carps in the Illinois River, U.S.A. Is this evidence for competition and reduced fitness?
Authors: Irons K. S. , Sass G. G. , McClelland M. A. , Stafford J. D.
Published: August 2010

Non‐native, Asian carps bighead Hypophthalmichthys nobilis and silver Hypophthalmichthys molitrix have been present in the Illinois River since the early 1990s. The Long‐Term Resource Monitoring Program (LTRMP) has been collecting bighead and silver carps in routine monitoring of the La Grange Reach, Illinois River, since 1995 and 1998, respectively. Despite variable recruitment, Asian carps abundance and biomass have increased since 2000, as evidenced by commercial landings, and Asian carps now dominate the fish community on La Grange Reach. Previous research suggests dietary overlap among bighead and silver carps and two native Illinois River fishes, gizzard shad Dorosoma cepedianum and bigmouth buffalo Ictiobus cyprinellus. Total length and mass data from c. 5000 fishes were used to test for changes in gizzard shad and bigmouth buffalo body condition after Asian carps establishment and investigate potential competitive interactions and changes in fitness. Analyses revealed significant declines in body condition of gizzard shad (−7%) and bigmouth buffalo (−5%) following the Asian carps invasion from 2000 to 2006. Segmented regression analyses showed no significant change in the rate of decline in gizzard shad condition after 2000, whereas the rate of decline in bigmouth buffalo condition increased significantly after 2000. Statistically significant differences in gizzard shad condition after Asian carps establishment (2000–2006) was observed, whereas condition of bigmouth buffalo was significantly lower in all years following Asian carps establishment as compared to 2000. Declines in gizzard shad and bigmouth buffalo condition were significantly correlated with increased commercial harvest of Asian carps and poorly correlated with other abiotic and biotic factors (e.g. temperature, chlorophyll a and discharge) that may influence fish body condition. These results may suggest that Asian carps are influencing native planktivore body condition, and future research should focus on determining whether food is limited in the Illinois River for native planktivores and other fish species.
The history of the minnow Phoxinus phoxinus (L.) in Norway: from harmless species to pest
Authors: Museth J. , Hesthagen T. , Sandlund O. T. , Thorstad E. B. , Ugedal O.
Published: August 2010

The causes, effects and extent of minnow Phoxinus phoxinus introductions in Norway are reviewed to assess why the introductions have had severe effects, especially where brown trout Salmo trutta is the only fish species present. The natural distribution of minnow in Norway was mainly restricted to low altitude localities in the south‐eastern part of the country and in some northern areas. The distribution area expanded considerably throughout the 1900s, especially in mountain areas, due in part to the use of minnows as live bait for angling. Although minnow densities do not seem unusually high in the relatively complex fish communities of its native range, the species can achieve very high population densities when introduced to communities with few fish species, such as in the numerous recently invaded lakes where brown trout was the only fish species present. The dense minnow populations in these lakes appear to have led to reduced recruitment and growth rates in the brown trout, with abundances on average 35% lower in lakes where minnow has been introduced. The success of minnow in harsh habitats demonstrates their phenotypic and ecological plasticity, but also implies that their original distribution in Norway was restricted by early immigration history and not by environmental limitations. This suggests that human‐assisted spread of the species could have strong adverse effects in Scandinavia lakes of low fish species richness.
Stable isotope evidence of trophic interactions between introduced brook troutSalvelinus fontinalisand native brown troutSalmo truttain a mountain stream of south‐west France
Authors: Cucherousset J. , Aymes J. C. , Santoul F. , Céréghino R.
Published: August 2010

The potential trophic impact of introduced brook troutSalvelinus fontinalison native brown troutSalmo truttain a mountain stream (south‐west France) was investigated using stable isotope analysis (SIA). The isotopic signatures (δ13C and δ15N) ofS. fontinaliswere similar regardless of the absence or presence ofS. trutta, and SIA mixing models revealed thatS. fontinalisdiet consisted mainly of terrestrial invertebrates. Conversely, a significant shift inS. truttaisotopic signatures (depletion of 1·6‰δ13C and enrichment of 0·6‰δ15N) was observed in sympatry withS. fontinalis; this may be due to a dietary shift towards terrestrial invertebrates. Contrary to an expected dietary divergence in sympatry, an elevated level of dietary overlap was observed between the non‐native and native salmonids when in co‐occurrence. This dietary convergence is more likely to be due to behavioural interactions than to variations in food availability or fish displacements.
Non‐native freshwater fishes in Norway: history, consequences and perspectives
Authors: Hesthagen T. , Sandlund O. T.
Published: August 2010

At present, there are 43 self‐sustaining fish species in Norwegian fresh waters, 11 (26%) of which are non‐native, representing four families (Salmonidae, Cyprinidae, Centrarchidae and Ictaluridae). Human‐mediated fish introductions probably began in the 15th century with common carpCyprinus carpio,but most have occurred between the late 1800s and late 1900s. The number of known established populations varies from one (goldfishCarassius auratus) to nearly 250 (tenchTinca tinca). Dispersal risk is also highest with tench, which is being spread by anglers for its appeal as a trophy fish. Intentional introductions to improve amenity angling have been part of fisheries management programmes (e.g.brook troutSalvelinus fontinalis), so this appears to be an increasingly common introduction vector despite the prohibition under legislation of introducing any species of non‐native fishes. Some introduced species, such as brook trout, have declined in abundance and number of populations as the quality of acidified waters has been restored, being replaced by native brown troutSalmo trutta. Further range expansion by some species (e.g.common carp, goldfish and pumpkinseedLepomis gibbosus) is probably restricted by current climatic conditions.
The influence of habitat availability and adult density on non‐diadromous galaxiid fry settlement in New Zealand
Authors: Jellyman P. G. , McIntosh A. R.
Published: August 2010

This study investigated factors controlling settlement and initial density of two species, Galaxias vulgaris and Galaxias paucispondylus (Galaxiidae), in New Zealand streams. Factors affecting maximum fry abundance were assessed at 10 sites (eight streams) differing in habitat characteristics and the presence or absence of introduced brown Salmo trutta and rainbow trout Oncorhynchus mykiss. Regression analysis indicated that conspecific adult numbers, extent of backwater habitat and brown and rainbow trout density were the most important factors determining initial fry density. Experimental additions of backwater habitat increased fry settlement tenfold compared with control reaches, demonstrating that the area available for fry settlement had a substantial effect on fry abundance. Results from this study indicate that fry settlement may be a critical limiting phase for some non‐diadromous galaxiid populations. Increasing settlement area to enhance fry retention offers a practical conservation tool for fisheries managers that may aid conservation of threatened fishes like galaxiids.
Determining diel variation in fish assemblages downstream of three weirs in a regulated lowland river
Authors: Baumgartner L. J. , Stuart I. G. , Zampatti B. P.
Published: August 2010

The diel variation in boat electrofishing catches was investigated on the lower Murray River (south‐eastern Australia), downstream of three low‐level weirs. Fish assemblage composition did not differ among three sites, but differed substantially between day and night. Significantly more small‐bodied species (e.g. Australian smelt Retropinna semoni, flyspecked hardyhead Craterocephalus stercusmuscarum, bony herring Nematalosa erebi and Murray rainbowfish Melanotaenia fluviatilis) and some large‐bodied predators (e.g. golden perch Macquaria ambigua) were caught during daytime samples. Significantly more flatheaded gudgeon Phylipnodon grandiceps, carp gudgeon Hypseleotris spp. and perch Perca fluviatilis were collected at night. The size composition of the fish assemblage also changed over the diel cycle. Significantly smaller goldfish Carassius auratus, flyspecked hardyhead, bony herring and Australian smelt were sampled during the day, while generally smaller individuals of golden perch and the common carp Cyprinus carpio were caught at night. These findings suggest that sampling during both day and night is required to adequately characterize riverine fish assemblages in the context of fish migration studies.
Early development of the skull of Sander lucioperca (L.) (Teleostei: Percidae) relating to growth and mortality
Authors: Löffler J. , Ott A. , Ahnelt H. , Keckeis H.
Published: August 2010

The early osteological development of the skull (chondrocranium and osteocranium) of the pikeperch Sander lucioperca was studied. Specimens were reared at two temperatures, 15·5 and 18·0° C, from hatching until 47 and 43 days after fertilization (DAF), respectively. The skeletal elements characteristic for the different developmental stages were the same at both rearing temperatures, but pikeperch reared at 15·5° C reached the developmental stages later. The formation of the functional complexes, the neurocranium, jaws and suspensorium, branchial basket and hyoid arch, was evaluated chronologically. The focus was on skull development during several functional changes: at hatching, at the shift from endogenous to mixed feeding, the shift to exclusively exogenous feeding and upon reaching the final prey‐capture mechanism. Growth in total length differed between fishes reared at the two temperatures, except during a phase of very slow growth from the end of the embryonic stage until the second larval stage. The latter phase, in which most of the bony elements of the viscerocranium started to form, was marked by high mortality. When exogenous feeding began, the growth rates at both temperatures increased distinctly and the first bony elements were formed in the neurocranium. Specimens reared at 18·0° C grew continuously, but those at 15·5° C showed a second period of slow growth and high mortality. Fish reared at 18·0° C reached the successive larval stages distinctly earlier than fish reared at 15·5° C.
Opportunistic predation by small fishes on epibiota of jetty pilings in urban waterways
Authors: Moreau S. , Péron C. , Pitt K. A. , Connolly R. M. , Lee S. Y. , Meziane T.
Published: August 2010

Epibiota were sampled on nine small jetties in the tidal, urban canals of south‐east Queensland, Australia, to determine if the small fishes that are associated with these jetties prey on the epibiota on the pilings of the jetties and whether these fishes depend on the epibiota as a source of food. Epibiota was dominated by barnacles, filamentous and foliose algae and ranged in thickness from 4 to 11 mm. The two species of fishes that associated most closely with jetty pilings, Pandaka lidwilli (Gobiidae) and Monodactylus argenteus (Monodactylidae), were sampled twice during the day and twice during the night for analysis of stomach contents. During the day, the diet of P. lidwilli was dominated by amphipods (c. 70%, by mass of organic content), with copepods, bivalves and bryozoans each contributing <10%. At night, amphipods contributed less (c. 45%) and copepods more (c. 35%). The diet of M. argenteus was dominated by filamentous algae (55%) and amphipods (20%) during the day and filamentous algae (70%) and barnacle cirri (23%) at night. Epibiota, therefore, made a substantial contribution to the diet of the fishes but were not the sole source of food for either species. As jetties were the only structures that supported epibiota in the area, fishes probably sourced their epibiota from the pilings of the jetties. Whether fishes depended on the epibiota was, therefore, tested using a manipulative before‐after‐control‐impact (BACI) study. Three jetties were assigned randomly to each of three treatments: (1) epibiota removed from pilings, (2) epibiota cut and damaged (a procedural control) and (3) epibiota left undisturbed. Abundances of P. lidwilli and M. argenteus around jetty pilings remained similar across all treatments from before to after the removal of epibiota. These results indicate that although fishes consumed epibiota on the jetties, they did not depend on the epibiota of the jetties for food.
A new West Balkanian sand‐goby (Teleostei: Gobiidae)
Authors: Miller P. J. , ŠAnda R.
Published: August 2010

A new species of West Balkanian freshwater sand‐goby Pomatoschistus montenegrensis sp. nov. (Teleostei: Gobiidae) is described from the Morača River, southern Montenegro, and shown to be related to the euryhaline Adriatic Pomatoschistus canestrinii. The generic status of these two species is discussed with reference to the limits of Pomatoschistus (type Gobius minutus) and the status of a subgenus [Ninnigobius (type‐species Gobius canestrini)]. The habitat and the local distribution of the new species are described.
Knodus dorsomaculatus (Characiformes: Characidae), a new species from Teles Pires River, Tapajós River basin, Brazil
Authors: Ferreira K. M. , Netto–Ferreira A. L.
Published: August 2010

Knodus dorsomaculatus, a new species, is described from Teles Pires River, a tributary of the Tapajós River, Brazil. It can be distinguished from its congeners by the presence of a conspicuous dark blotch on the base of the first five branched dorsal fin rays and the presence of ii,9 dorsal fin rays. Additional comparisons between K. dorsomaculatus and its congeners are presented.
Proximity to the US–Mexico border: a key to explaining geographic variation in US methamphetamine, cocaine and heroin purity
Authors: Cunningham James K. , Maxwell Jane Carlisle , Campollo Octavio , Cunningham Kathryn I. , Liu Lon‐Mu , Lin Hui‐Lin
Published: August 2010

Aims Although illicit drug purity is a widely discussed health risk, research explaining its geographic variation within a country is rare. This study examines whether proximity to the US–Mexico border, the United States' primary drug import portal, is associated with geographic variation in US methamphetamine, heroin and cocaine purity.

Design Distances (proximity) between the US–Mexico border and locations of methamphetamine, cocaine and heroin seizures/acquisitions (n = 239 070) recorded in STRIDE (System to Retrieve Information from Drug Evidence) were calculated for the period of 1990–2004. The association of drug purity with these distances and other variables, including time and seizure/acquisition size, was examined using hierarchical multivariate linear modeling (HMLM).

Setting Coterminous United States.

Findings Methamphetamine, cocaine and heroin purity generally decreased with distance from the US–Mexico border. Heroin purity, however, after initially declining with distance, turned upwards—a U‐shaped association. During 2000–04, methamphetamine purity also had a U‐shaped association with distance. For each of the three drugs, temporal changes in the purity of small acquisitions (<10 g) were typically more dynamic in areas closer to the US–Mexico border.

Conclusions Geographic variance in methamphetamine, cocaine and heroin purity throughout the coterminous United States was associated with US–Mexico border proximity. The U‐shaped associations between border‐distance and purity for heroin and methamphetamine may be due to imports of those drugs via the eastern United States and southeast Canada, respectively. That said, areas closer to the US–Mexico border generally had relatively high illicit drug purity, as well as more dynamic change in the purity of small (‘retail level’) drug amounts.
Case studies of tobacco dependence treatment in Brazil, England, India, South Africa and Uruguay
Authors: Raw Martin , McNeill Ann , Murray Rachael
Published: August 2010

Aims  The aims of this study are to describe the tobacco dependence treatment systems in five countries at different stages of development of their systems, and from different income levels and regions of the world, and to draw some lessons from their experiences that might be useful to other countries.

Methods and data sourses  Data were drawn from an earlier survey of treatment services led by M.R. and A.M., from Party reports to the Secretariat of the Framework Convention on Tobacco Control, and from correspondents in the five countries. These data were entered onto a standard template by the authors, discussed with the correspondents to ensure they were accurate and to help us interpret them, and then the templates were used as a basis to write prose descriptions of the countries' treatment systems, with additional summary data presented in tables.

Results  Two of the middle‐income countries have based their treatment on specialist support and both consequently have very low population coverage for treatment. Two countries have integrated broad‐reach approaches, such as brief advice with intensive specialist support; these countries are focusing currently upon monitoring performance and guaranteeing quality. Cost is a significant barrier to improving treatment coverage and highlights the importance of using existing infrastucture as much as possible.

Conclusions  Perhaps not surprisingly the greatest challenges appear to be faced by large, lower‐income countries that have prioritized more intensive but low‐reach approaches to treatment, rather than developing basic infrastructure, including brief advice in primary care and quitlines.