bluuebunny/crossref_metadata_2025 huggingface dataset:
Spawning behaviour and acoustic communication in Atlantic cod
Authors: Rowe S. , Hutchings J. A.
Published: December 2003

Mating systems are defined by the pattern of matings among individuals in a population, including the number of mates obtained by each female and male, and the duration of pair bonds. Within all mating systems, mate choice, intra‐sexual competition, and sperm competition may lead to variation in mating success among individuals. Growing evidence indicates that quantification of the patterns and processes of mating may be critical to understanding population dynamics. Atlantic cod had been fished for hundreds of years and was one of the most important commercial fish species worldwide until the recent collapse of many populations. Despite being of theoretical interest and practical importance, little was known about this species’ reproductive behaviour. Our research employed a quantitative approach to understand causes and consequences of variation in the mating system of Atlantic cod at the individual and population levels. We incorporated both detailed behavioural studies in the laboratory and observations of cod captured in the commercial fishery. Preliminary observations indicate tremendous variation in reproductive behaviour and mating success both within and between populations. Furthermore, variation in reproductive behaviour and mating success appears to be related to the ability of males to produce sound. Knowledge of Atlantic cod spawning behaviour will likely contribute to better understanding of population dynamics and improved ability to predict the impact of fishing on cod populations.
Do competing males cooperate? Familiarity and its effect on cooperation during predator inspection in male three‐spined sticklebacks (Gasterosteus aculeatus)
Authors: Walling C. A. , Dawnay N. , Kazem A. J. N. , Hickling R. , Wright J.
Published: December 2003

We investigated the trade‐off between conflict and cooperation, using predator inspection behaviour in sticklebacks as a model system. Male three‐spined sticklebacks (Gasterosteus aculeatus) compete for territories during the breeding season and it has been demonstrated that the level of aggression between territorial neighbours declines with time, a phenomenon known as the dear enemy effect. In this experiment we examine whether this increase in familiarity between territorial neighbours can facilitate an increase in cooperation during predator inspection events. This was analyzed using male sticklebacks from four pond populations, two with and two without predatory rainbow trout (Oncorhyncus mykiss). Males were each exposed to five different treatments: (1) the presentation of a live rainbow trout when alone; (2) with a newly revealed territorial neighbour; (3) with this neighbour after two days of familiarization; (4) with another unfamiliar neighbour (termed a ‘floater’); and (5) a second solitary trial (to provide controls at the start and end of the experiment). As predicted, fish from predator‐sympatric populations showed higher levels of predator inspection and lower rates of misdirected territorial aggression towards the predator throughout. However, familiarity between neighbouring males did not facilitate an increase in predator inspection behaviour. Instead, predator inspection behaviour decreased throughout treatments involving the presence of any sort of neighbouring male. Familiarity between neighbours did not influence their ability to cooperatively inspect, but only the nature of any aggressive territorial behaviours, all of which detracted equally from individual inspection effort.
Fertilisation and sperm competition dynamics in salmon
Authors: Yeates S. , Gage M.
Published: December 2003

Fishes have evolved an enormous range of mating patterns and sperm competition is important in the majority of these. Detailed mechanisms of fertilization and sperm competition dynamics at the gamete level are poorly understood. We have been using salmon models to conduct in vitro fertilization trials that: (1) allow us experimental control, (2) eliminate confounding effects from the whole organism, and (3) enable detailed measures of sperm form and function in the natural fertilization medium to which gametes are adapted. Using both Atlantic and sockeye salmon, we present results on experiments exploring: (1) the importance of relative sperm number, size, % motility, longevity, and velocity for fertilization and sperm competition success, (2) the importance of natural variation in egg size for ‘fertilizability’ under sperm limited conditions and (3) the influence of ovarian fluid in fertilization dynamics.
Predator prey interactions: predator choice for prey group size and composition in Crenicichla alta, a natural predator of the Trinidadian guppy, Poecilia reticulata
Authors: Botham M. , Krause J.
Published: December 2003

The anti‐predator benefits of shoaling behaviour in fish are well documented. As a result many studies have investigated the shoaling decisions that prey species make. Although the effects on predator success of different groups have been researched, the choices that predators make when confronted with multiple shoals of different size and composition have received much less attention. We investigated the decisions made by pike cichlids, Crenicichla alta, caught in the Arima river, Trinidad, when offered shoals of guppies, Poecilia reticulata, of different size and composition. The predators showed a significant preference for larger over small shoals and for shoals of large over shoals of small individuals. They showed no preference for shoals consisting of an odd individual over those without.
Diffusion in the littoral zone: scoping emergence times and movement to essential habitat for young‐of‐year brook trout in lakes
Authors: Coombs M. F. , Ridgway M. S.
Published: December 2003

Factors governing the process of dispersal of lake‐spawned brook trout (Salvelinus fontinalis) young‐of‐year (YOY) appear drastically different from those governing dispersal in more commonly studied stream salmonids. Rather than dispersal being highly density‐dependent and the result of territoriality and aggression, in brook trout it may be density‐independent and driven by a common need for coldwater habitat for summer survival. Emerging fish travel great distances from single spawning sites on lakes to cold groundwater habitat. Movement is a gradual, one‐dimensional diffusion around lake margins and represents a very unique and simplified natal dispersal pathway allowing for dispersal rates, distances, and factors controlling these parameters to be measured. We predicted timing of the emergence period for brook trout alevins from lake spawning sites using the known relation between water temperature and emergence times for salmonids. Emergence and dispersal was then observed in the field by visually estimating YOY density in segments of the littoral zone throughout the dispersal period. Fluxes in density in these sections were used to estimate rate of YOY spread. YOY behaviour and body condition was also assessed across the wave of spatial spread. We are working towards a spatially explicit model to identify critical groundwater rearing habitat needing protection from forestry activities.
Fish behavioural responses to river discharge trends and the importance of habitat connectivity
Authors: Copp G. H. , Carter M. G. , Faulkner H.
Published: December 2003

Population behaviours associated with the migrations of coarse (non‐salmonid) fishes within river basins are amongst the most poorly understood dispersion mechanisms of temperate freshwater organisms, which in rivers are expected to be influenced by river discharge. We examined the timing and intensity of fish movements (via trapping) between the River Avon (Hampshire, England) and a small floodplain tributary, Ibsley Brook, and tested for correlations with trends in river discharge (i.e. mean cm of change in stage during trapping), water temperature and brook water velocity over twelve months in 1999–2000. 0‐group fishes dominated the catches. Intensities of movement between the brook and the river were similar in most months, but seasonal patterns were observed overall and for individual species. Few significant differences in overall numbers of fish were observed between the discharge trends, but many individual species demonstrated differences, mostly as more intense movement under fast rising discharge. Fish numbers in five species were correlated with river discharge trend, and movements in some species were correlated with the rate of temperature change (Δ° C 10 h sampling), and with changes in brook water velocity. Our results suggest daily movements between the river and small tributary brooks are triggered by changes in light intensity and water velocity, whereas seasonal movements of species between the river and brook are driven by changes in river discharge and water temperature, in particular associated with flood events. This study emphasizes the importance of connectivity in river systems, as fish movement between the Avon and its annexes occur under all flow regimes, but especially with rapidly rising discharge.
Ectoparasites: are they the proximate cause of cleaning interactions?
Authors: Côté I. M. , Molloy P. P.
Published: December 2003

We tested the importance of ectoparasites in cleaning symbioses by comparing the activity of Caribbean cleaning gobies (Elacatinus evelynae) and of their clients during three daily periods (early morning, midday and late afternoon) in which ectoparasite availability varied naturally. Emergence from the benthos of gnathiid isopod larvae, the main target of cleaning goby predation, was higher at night, when cleaners are inactive, than during the day. Overall ectoparasite loads also tended to be higher on clients in the morning. This coincided with higher rates of visits to cleaning stations by client fish in the morning than at midday, but high rates of client visits were also recorded in the late afternoon. Clients were more likely to adopt stereotypical incitation poses, which increase the likelihood of being cleaned, in the morning than later in the day. Inspection bouts by cleaning gobies were longest in the morning. Cleaner and client behaviours therefore change predictably in response to natural diurnal variation in ectoparasite availability. These results add to a growing number of studies supporting the idea that cleaning symbioses are mutualisms dependent on ectoparasite removal.
Up or down? Explaining the variability of communication signals in cleaning symbioses
Authors: Côté I. M. , Whiteman E. A.
Published: December 2003

In this study, we used cleaning symbioses among coral reef fishes as a model system to investigate the form and function of signalling in interspecific mutualisms. More specifically, we examined the causes and significance of inter‐specific and inter‐individual variation in the design of client solicitation poses in cleaning interactions with Caribbean cleaning gobies (Elacatinus spp). Using empirical data collected during field observations at cleaning stations, we tested three hypotheses: (1) The form of client incitation poses depends on species‐specific features; (2) Intraspecific variability in the form of client poses reflects the strength of each cleaner‐client relationship; and (3) Client individuals that deviate from a clear species‐specific form of pose will receive a different cleaning service. As predicted by (1), we found that the type of incitation pose was related to client body size, with small species performing mainly head‐down displays which may facilitate retreat into coral cavities upon predator approach. There was nevertheless some intraspecific variation in the type of display performed by clients, which was negatively related to client ectoparasite load, as predicted by (2). Hence, species with higher ectoparasite loads, and thus with a greater need to be cleaned, were less variable in display form than clients with fewer ectoparasites. Finally, cleaning gobies inspected for longer those individual clients that performed the species‐specific solicitation poses (3). We conclude that solicitation poses function to minimize uncertainty about a client's need to be cleaned and that their design has been partly determined by the risk of predation on posing clients.
Variation of reproductive behaviour and success of males adopting different tactics in Atlantic salmon
Authors: De Gaudemar B. , Beall E.
Published: December 2003

Six males and five females anadromous Atlantic salmon were released in two sections of the Lapitxuri experimental stream (Southwest France), where they could reproduce naturally. Females had all the same size and age, contrary to males. We focussed our attention on the variation with time of spawning tactics and success of males. Two factors affected male spawning behaviour in the short term. An increase of the OSR increased the level of male competition around redds which resulted in a larger number of males adopting sneaking rather than fighting tactics. Changes in female activities also seemed to be detected by males, since male aggressiveness increased when females were close to oviposition. But whatever their activities, males preferentially courted the earlier spawning female when two females were active at the same time. Fighting in males was confirmed to be the most successful tactic at a given time. However, males adopting sneaking tactic at the beginning of the spawning season could dramatically increase their reproductive success in the long‐term. Fighting males invested much more energy in contests than secondary males, which may constitute a handicap in terms of longevity. They could quickly lose their status or strength with time which, although placed in a situation of high OSR, resulted in greater numbers of previously low‐ranking males adopting satellite and fighting tactics during the period preceding oviposition. Age more than size affected male status and reproductive success. Females seemed to select their mate directly in relation to their physiological condition, since they only attacked dull coloured males showing obvious wound marks. They also could indirectly choose their mate by repeatedly leaving the redd during the period preceding oviposition in a situation of high OSR. This behaviour might incite male competition and also promoted, by incessant attempts of secondary males to rob the more successful status of primary males, their chance to spawn with fitter males. These results emphasized the importance of environment, physiological condition and energy expenditure in allocation tactics and variations in salmon reproductive success throughout the spawning season. This led us to hypothesize that the choice of sneaking through conditional strategies might provide greater average fitness in salmon alternative life histories.
Size dominance affecting the social interactions and growth of juvenile Japanese flounder, Paralichthys olivaceus
Authors: Dou S. , Msuda R. , Tanaka M. , Tsukamoto K.
Published: December 2003

Juvenile flounder Paralichthys olivaceus were size‐graded into three groups (small, large and mixing of small and large) and social interactions (feeding, aggressive attacking and activity) and growth of the fish were investigated. Growth of the subordinates (small flounder) was markedly suppressed by the presence of the dominants (large flounder). Dominants did not significantly suppress the overall food intake of the subordinates, but exhibited high aggressive attacking on the subordinates and consequently inhibited their activity. Size dominant interactions had little influence on the aggressive behaviour, feeding, activity and growth of the dominants. Results substantiated the hypothesis that the retardation in the growth of the subordinate flounder was attributed to the physiological costs of ‘stress’ by the aggression of the dominants. Individual differences in aggressive behaviour, feeding and activity were at least partly responsible for the growth depensation of the juvenile flounder. The dominants could not effectively defend the food in excess and disproportional food acquisition of the subordinates and dominants was not the primary mechanism responsible for the size hierarchy effect. In culture, size grading of the early juvenile flounder could markedly improve the growth and survival and thus possibly increase the overall biomass production of the flounder.
Function and variability of male sex traits in a blenniid fish, Parablennius tentacularis
Authors: Giacomello E.
Published: December 2003

The theory of sexual selection aims to explain the occurrence of secondary sex traits and sexual dimorphism. In this context, fish represent an excellent model, as they show a wide array of reproductive modalities and a high variability of their sex traits, both at intra‐ and inter‐specific level.

This study is focused on the function and development of male sex traits in Parablennius tentacularis, a species releasing demersal eggs and with male parental care. This blenny is sexually dimorphic: males exhibit both external and internal dimorphic characters. Indeed, males show large orbital tentacles and bulb glands on the spiny anal finrays, called anal glands, and their reproductive apparatus is provided with accessories structures as the testicular glands and the blind pouches.

Field data were collected in a rocky area in shallow waters of the Northern Adriatic sea. During the breeding season, males of P. tentacularis are found inside empty shells, which they adopt as nests, and where they care for eggs. Differently sized nesting males were collected; their external sex traits were measured and gonado‐somatic index calculated. Size and type of nest were recorded and the total egg number was estimated to obtain an evaluation of male mating success. Intraspecific variability of male sexual traits is discussed in relation to individual mating success and the possible presence of sperm competition.
The Amarillo (Girardinichthys multiradiatus) a fish model to study geographic variation in mate recognition systems
Authors: Gonzalez‐Zuarth C. , Avila E. , Macías Garcia C.
Published: December 2003

The existence of a species‐specific mate recognition system (MRS) enables a fluid interchange of genes within species, while promoting the evolution of barriers to hybridization across sibling species. This is because MRS's can diverge in allopatry as a consequence of random events such as drift, or because different ecological conditions impose different optima on sexually‐selected characters such as may be part of the MRS’s. As freshwater habitats are frequently fragmented and re‐merged following long‐term climatic changes and river piracy across catchments, there is ample scope for fish populations’ MRS's to diverge in allopatry to the point of generating pre‐mating barriers. Based on former records of population differences in sexually‐dimorphic traits in the Amarillo fish (Girardinichthys multiradiatus), we investigated 1) whether courtship by males is quantifiably different between populations, and 2) whether these differences are due to difference in the way females respond to specific elements of the courtship sequence (thus prompting males to court in a population‐specific style). Using five populations representing the whole of the Amarillo's geographic range, we found that, when confronted to homogametic females, males exhibited substantial and significant differences in the tendency to perform particular courtship patterns, in spite of males form all populations having equal repertoires. We also found that heterogametic courtship neither resembled that of the populations of origin of the male, nor of the female. We infer that the interpretation of the courtship signals is diverging across Amarillo populations, in a manner akin to the evolution of languages in bird songs.
The aberrant stickleback Gasterosteus aculeatus in the Karlskrona archipelago, SE Sweden
Authors: Lindén M. , Påhlson C. , Nilsson J.
Published: December 2003

The aberrant stickleback in the Karlskrona archipelago is probably a completely new form within the three‐spined stickleback Gasterosteus aculeatus complex. Males of this type differ from sympatric, normal stickleback males by being smaller and by having less striking nuptial coloration. They also build nests in algae above the bottom, whereas normal stickleback males build their nest at the bottom. Moreover, observations suggest that aberrant stickleback males have emancipated from most of the care of nest and offspring as they appear to transport fertilized eggs from the nest to the surroundings where they are left unattended. Whether this can be explained by sex‐specific reproductive strategies or by any other means is investigated. Preliminary results suggest the aberrant stickleback to be genetically distinct from regular morphs. The project will investigate this further and hopefully clarify whether the aberrant type has evolved in the Karlskrona archipelago, thus probably in sympatry with normal sticklebacks, or if it is of allopatric origin. With reproductively important morphological and behavioural deviations, our first guess would be that isolation is mediated through sexual selection. If this is true, isolation may have been relatively rapid making a sympatric origin less unlikely. The aberrant form is very rare and endangered. Presently, it is only found at two sites, both of which are threatened by an impending ferry terminal construction. A major aim of the project is to help preserve the aberrant stickleback. Most importantly, aberrants will be collected for captive breeding and introduction to new localities.
Alternative mating tactics and acoustic behaviour in the grass goby Zosterisessor ophiocephalus: a behavioural analysis of the interaction between the parasitic and the bourgeois male
Authors: Malavasi S. , Lugli M. , Torricelli P. , Mainardi D.
Published: December 2003

In this study the behavioural interaction between the bourgeois and the parasitic male of the grass goby, Zosterissor ophiocephalus, is investigated during spawning in the laboratory. Large grass goby males care for the eggs (bourgeoise males), whereas small males are believed to adopt an alternative mating tactic. The behavioural interaction between one large male spawning inside an artificial nest (a large plastic box buried in the sand provided with two entrance tubes opening on the substrate) and one small male, was investigated in five small male‐large male pairs. The small male performed parasitic activity in four replicates. The main activity of the parasitic male was staying still on the substrate by one nest opening (Waiting), usually followed by one or more attempts to enter the nest. Waiting was performed repeatedly by the parasitic male at both nest openings across the spawning period. The activity of the large male inside the nest consisted mainly of switching between spawning‐related activities (e.g. Upside‐down) and standing still inside one of the two entrance tubes of the nest (Patrolling). The analysis of temporal relationship among behavioural activities showed a positive relationship between the occurrence of Waiting and Patrolling in 3 out of 4 replicates, with Patrolling occurring more frequently at the nest opening at which the parasitic male was Waiting. Only 20% of all the intrusion attempts observed in the five replicates were successful, i.e. the parasitic male entered the burrow and performed egg‐fertilization movements. A significant emission of sounds by the bourgeois male, mostly associated with Patrolling, was documented. The function of the bourgeois male sound production during spawning is discussed.
Ontogeny of the diel activity patterns in relation to downstream dispersal in riverine cyprinid fishes
Authors: Ondračková M. , Mazurová E. , Reichard M. , Jurajda P.
Published: December 2003

Young‐of‐the‐year (YOY) riverine fish use the facility of water currents to disperse downstream from their spawning sites. We combined data on the diel changes in YOY fish activity and their distribution in the river to investigate a relation between the onset of their downstream movement and ontogeny of their diel activity. Plexi‐glass traps and electrofishing were used to investigate the activity and distribution of YOY fish. Fish species such as Leuciscus leuciscus, Leuciscus cephalus, Chondrostoma nasus, Barbus barbus and Rutilus rutilus dominated our samples from two separate study sites in the River Morava. Results are discussed in context of ontogeny of phototrophic and rheotrophic behaviour, seasonality, diel periodicity and stage‐dependence of the downstream movement and also in relation to environmental (river discharge, water temperature) variability.
Do early life history characteristics determine species ranges and dispersal of coral reef fishes in the Indo‐Pacific?
Authors: Priest M. A. , Simpson S. D. , Dytham C.
Published: December 2003

The Indo‐Pacific consists of extensive continuous coastlines and many island groups of varying sizes and isolation. The species ranges of coral reef fishes vary enormously from Indo‐Pacific wide to highly endemic. There is also great variation in the early life history characteristics of coral reef fishes (e.g. pelagic larval durations, spawning strategies and swimming abilities). We use individual‐based models (IBMs) to simulate the dispersal of coral reef fishes in the Indo‐Pacific. The development of dispersal strategies is explored based on ecological and geographical constraints. Simulations are presented for climatic and anthropogenically‐induced events.
Visual isolation furthers access to drift‐feeding positions for subordinate juvenile brown trout (Salmo trutta) in dominance hierarchies
Authors: Roussel J‐M. , Agnès B.
Published: December 2003

Juvenile salmonids are visual predators that primarily feed on drifting invertebrates and compete for suitable feeding positions in swift water. We used an outdoor experimental stream to test the effect of visual isolation on agonistic interactions and habitat use by age‐1 brown trout (Salmo trutta) in riffle‐pool sections. We hypothesized that dominant fish defend suitable feeding positions in riffle and that visual obstruction between individuals enhance access to riffle for subordinates. Groups of juveniles, caught in the wild, were stocked in high and low visibility treatments. Visual isolation was manipulated by placing dark plastic ribbons or opaque Plexiglas boards onto the substrate of riffles. As expected, dominant fish held profitable positions in riffle and the proportion of fish in riffle significantly increased in presence of artificial structures. In high visibility treatment, the dominant fish despotically excluded subordinates from the riffle. In low visibility treatment, the proportion of fish that foraged on benthic prey in the pool and the number of major aggressive acts (chase, nip) decreased. Our results support the hypothesis that screening effect of physical structures in the water column loosen resource monopolization in dominance hierarchies of juvenile salmonids.
Teaching hatchery cod about environmental heterogeneity
Authors: Salvanes A. G. V. , Braithwaite V.
Published: December 2003

Restocking fish species may be one way to overcome problems of overfishing or dwindling natural populations. To date, most restocking programs have failed. We believe that these failures are, in part, due to the sparse, uniform rearing environment that fails to teach the fish about heterogeneity. We report experiments in which the early rearing environment of juvenile cod were manipulated to generate experience of environmental variability. We manipulated two key variables; food and spatial cues. We found that manipulations to either or both of these cues had effects on a number of behaviours and produced fish that varied in terms of boldness, stress recovery and the speed with which they were able to transfer from a diet of pellet food to natural prey.
Adaptive significance of sex change in the stone loach (Nemachilus angorae)
Authors: Sari A.
Published: December 2003

Previous comparative studies, using multivariate analyses, on two sympatric loaches, Nemachilus angorae and N. malapterurus in Jajroud river, Iran, revealed some degrees of morphological similarity of larger males to female individuals only in the former species. Later, histological studies of testis resulted in observation of some mature oocytes mostly in testes of larger males. Their gonad was similar to ovotestis of hermaphroditic fish. To find out about the sex change in male N. angorae, several hypothesis were tested including: effects of pollutants, interspecific competitions for resources, man‐made habitat alteration, lack of enough rain at least for three years and population structure on sex change. It seems that population structure in N. angorae is an important factor with significant impacts on reproductive behaviour and subsequent changes in both sex and morphology of male individuals. In this case, there is a tendency to have a sex change in favour of less abundant sex (female). This is more pronounced in larger male fish which have higher ability to produce eggs and have no chance to produce offspring in the coming year.
The yellow stingray, Urobatis jamaicensis, as a model for studying cerebellar function in vertebrates
Authors: Sherman R. L. , Barnes J. W. , Huston J. P. , Spieler R. E.
Published: December 2003

Fishes, in general, have several advantages as vertebrate models for basic brain function. They are phylogenetically closer than mammals to the basic vertebrate blueprint and thus allow behavioural and neurological studies of fundamental brain systems without the interaction of more recently evolved functions. Further, the absence of a highly developed telencephalon allows ready access to many structures without cerebral interference. A disadvantage of working with most fishes is, however, the relatively small size of the brain that often hinders or precludes the use of many standard neurological techniques. In contrast, a group of chondrichthians, the stingrays, Dasyatoidea, has a brain size rivaling mammalian rodent models. Of particular interest to our research, stingrays, like mammals, have a large, complex, three‐lobed cerebellum. However, in the yellow stingray these lobes are completely separated. Thus, the lobes can be individually manipulated to examine behavioural correlates of specific lobes. For example, ablation of the centre lobe (also known as anterior caudal lobule) causes a fixed‐pattern hyperactivity. Yellow stingrays are abundant in many areas, they are hardy, and tolerate anaesthesia and the surgical procedures well. A more complete elucidation of cerebellar function awaits further physical and pharmacological ablative studies but the potential for these animals as vertebrate models of cerebellar‐controlled behaviour is clear.
Estimating size dependent diet, advection, diffusion, catchability and mortality applying a normal distribution model to spreading of released turbot
Authors: Sparrevohn C. R. , Nielsen A.
Published: December 2003

In a field experiment, breed turbot of an average length between 7–25 cm was released into a small bay. During the following week; diffusion rate, mortality and catchability of the released fish was estimated daily, by using a normal distribution model. In this model the size of the fish was incorporated in such a way, that it was possible to retrieve information about how each of the estimated parameters depended on the fish size. In addition, the length of the prey items found in the stomach was measured and compared to the prey length available in the habitat. Turbot was found to adjust to eat the available prey fast, after 3 days approximately 100% had detectable signs of prey in their stomach.
Bottom substrate preference in wild and reared turbot Psetta maxima L.
Authors: Sparrevohn C. R. , Støttrup J. G.
Published: December 2003

Structural complexity and bottom sediment preference was examined in the laboratory for 3 groups of juvenile turbot in order to gain information on habitat preference. For the experiments, a 4 m2 large tank was divided into 4 equal‐sized squares each with a different bottom type; sand (0·3–0·6 mm in diameter), gravel (18–25 mm in diameter), sand/gravel and sand/vegetation. The experiments were carried out with both wild and reared turbot. Two experiments with reared fish included one small (8·5 cm) and one large (11·5 cm) size group of turbot. Further, one group with large wild fish (18·0 cm) was also analyzed. A preference for sand was evident in all the groups. These results highlighted the importance of sand bottom for turbot and it should be kept in mind when evaluating the impact from different habitats on the recruitment, the bottom substrate might play an important role.
Cod in hot water: observations of behaviour in relation to temperature
Authors: Turner K. , Righton D.
Published: December 2003

Fish behaviour varies considerably in response to changes in environmental and biological conditions. Cod (Gadus morhua) is not a homeothermic species and recent research has suggested that the recruitment and distribution of cod stocks may be influenced by temperature. Concerns have therefore been raised about the potential effect of climate change on stocks that are already at the southern limits of their range. We used data storage tags (DSTs) to observe the behaviour of cod in relation to temperature between 1999 and 2002. Over 3500 days of data were collected from 17 individuals tagged in the North and Irish Seas. We describe how the patterns in the temperature experience of cod are related to behavioural mechanisms, such as horizontal and vertical migration, that match habitat choice to physiological preferences. The results are discussed in the context of this behavioural response to short‐ and long‐term shifts in thermal regime and the potential consequences on the overall behaviour and distribution of cod stocks.
Inter and intra‐population variation in shoaling and boldness in the zebrafish (Danio rerio)
Authors: Wright D. , Rimmer L. B. , Pritchard V. L. , Butlin R. K. , Krause J.
Published: December 2003

Population differences in anti‐predator behaviour have been demonstrated in several species, although less is known about the genetic basis of these traits. To determine the extent of genetic differences in boldness (defined as exploration of a novel object) and shoaling within and between zebrafish (Danio rerio) populations, and to examine the genetic basis of shoaling behaviour in general, we carried out a study that involved laboratory‐raised fish derived from four wild‐caught populations. Controlling for differences in rearing environment, significant inter‐population differences were found in boldness but not shoaling. A larger shoaling experiment was also performed using one of the populations as the basis of a North Carolina type II breeding design (174 fish in total) to estimate heritability of shoaling tendency. A narrow‐sense heritability estimate of 0·40 was obtained, with no apparent dominance effects.
(S)he who dares, grows! A cross‐population study of growth and behaviour in three‐spined sticklebacks
Authors: Wright H. A. , Wootton R. J. , Barber I.
Published: December 2003

Three‐spined sticklebacks (Gasterosteus aculeatus) exhibit considerable inter‐population variation in behaviour, morphology and life history characteristics. Such population‐level variation can be generated directly by environmental characteristics of the water body they inhabit (e.g. temperature regimes, which directly influence growth rates) but local genetic adaptation is also important. By performing ‘common garden’ experiments, in which laboratory‐bred individuals from separate populations are raised under standardized controlled laboratory conditions, it is possible to identify genetically‐based population‐level phenotype variation. Here we present the results of two studies, carried out using juvenile three‐spined sticklebacks bred from parental stock from five geographically isolated UK populations and reared under standard laboratory (‘common garden’) conditions. Firstly we report the results of a study examining population‐level variation in patterns of early growth, in which we tracked the growth of replicate groups of full‐sibs from all five populations, from hatching to 126d. Secondly we report the results of an experimental behavioural study, designed to examine population‐level variation in the exploratory or ‘boldness’ behaviour of laboratory‐bred and reared juvenile three‐spined sticklebacks from the same five populations. We discuss how adaptive genetically based patterns of behaviour and growth may co‐vary across populations.
The Effects of Auditor Gender and Task Complexity on Information Processing Efficiency
Authors: O'Donnell Ed , Johnson Eric N.
Published: December 2003

This paper examines whether auditor gender and task complexity interactively influence audit judgment efficiency as predicted by the selectivity hypothesis (Meyers‐Levy 1989). Twenty‐eight practicing auditors (16 males and 12 females) from four Big Five audit firms performed an analytical procedures task at one of two complexity levels. Consistent with a selectivity explanation, female auditors demonstrated significantly greater efficiency than males on a complex analytical procedures task. Additionally, female auditors exhibited greater efficiency in information processing on the more complex task than on the less complex task, while males demonstrated greater efficiency on the less complex task than on the more complex task.

Prior research (Chung and Monroe 1998; 2001) has demonstrated gender‐based differences in information processing effectiveness. Thus, the current study extends gender‐based performance in auditing across different tasks. These results highlight the importance of considering the effects of systematic gender‐based differences in auditor information processing.
Two Factors Affecting Internal Audit Independence and Objectivity: Evidence from Singapore
Authors: Goodwin Jenny , Yeo Teck Yeow
Published: December 2003

This study examines two factors that may influence the independence and objectivity of internal audit. The first, affecting the organizational independence of the internal audit function, is its relationship with the audit committee. The second is the use of the function as a management training ground. It is argued that this practice might affect individual objectivity because internal auditors may be reluctant to withstand pressure from an auditee who could be their future supervisor. A survey of chief internal auditors in Singapore was undertaken to establish current practice in these areas and to identify relationships between these variables. A strong relationship between the audit committee and the internal audit function was found, with the level of interaction being greater when the audit committee was comprised solely of independent directors. The use of the internal audit function as a management training ground was also found to be quite widespread in Singapore.
The Importance of Auditing Topics to Chinese Auditors
Authors: Davidson Ronald A. , Chang Stanley
Published: December 2003

This paper describes the recent history of auditing in China and reports on a survey of Chinese auditors and accounting academics on the importance of a number of auditing topics. We find that Chinese auditors are concerned about their professional responsibilities and legal liabilities, probably resulting from the recent instances of the imposition of severe penalties for breaking the law. We also find that Chinese auditors appear to be more concerned with what we might refer to as the traditional financial audit approach, and are not yet at the stage of using a risk‐based audit approach.
An Examination of the Effects of Accountability when Auditors are Uncertain about the Views of Superior Partners
Authors: Kaplan Steven E. , Lord Alan T.
Published: December 2003

This experiment focused on the effect of accountability on senior audit managers' reporting decisions related to ambiguous scenarios, where the auditors could only speculate on the views of superior auditors on specific reporting issues. It examines the potential effect of accountability on the relationship between judgments an auditor would make versus the judgments the auditor perceives superior partners would make. In particular, accountable auditors were predicted to engage in a hybrid strategy of processing information with more effort and of complying more with views they perceived to be held by the superiors. Consistent with the acceptability heuristic, the results indicate that accountability is associated with greater agreement between self‐judgments and judgments the auditor perceives superiors would make. However, contrary to Tetlock's (1992) theory but consistent with some prior research (Johnson and Kaplan, 1991; Hoffman and Patton, 1997), the accountability treatment did not significantly affect the auditors' processing of information.
How is Audit Quality Perceived by Big 5 and Local Auditors in China? A Preliminary Investigation
Authors: Chen Charles J.P. , Shome Anamitra , Su Xijia
Published: December 2003

This study seeks to determine what attributes are perceived by various groups of players in the Chinese auditing market as being important to audit quality. Attributes of audit quality were incorporated into a survey instrument which was administered to auditors from a local CPA (Certified Public Accountant) firm and a Big 5 firm operating in Shanghai, as well as subjects belonging to another group—regulators. Results indicate that the attributes perceived as having the most positive effect on audit quality correspond to a very high degree with those identified in the prior (mostly US‐based) literature. Attributes thought to be most detrimental to audit quality, on the other hand, were developed from consultations with key players, and were unique to the Chinese context. Wide differences were observed between auditors and regulators (e.g., regulators and Big 5 auditors), but not among the independent practitioners (local CPAs and Big 5 auditors). In addition to heightening the current understanding of what attributes of audit quality are important to audit firms operating in emerging markets such as China, these findings are expected to hold significant implications for strategy formulation by public accounting firms in China, both local as well as international.
Enhancing outcomes in the management of treatment resistant depression: a focus on atypical antipsychotics
Authors: Kennedy Sidney H , Lam Raymond W
Published: December 2003

Abstract: Clinical trials indicate that over 50% of depressed patients show an inadequate response to antidepressant therapy, and that incomplete recovery from major depressive disorder (MDD) increases the risk of chronicity and recurrence. Recovery, complete remission of symptoms, and a return to baseline psychosocial function, should be the goal of therapy. Poor response to adequate antidepressant treatment has been termed treatment resistant depression (TRD). Issues such as adherence, missed diagnosis of psychotic depression, bipolar disorder, or comorbid anxiety must be investigated as reasons why patients have not responded to initial therapeutic strategies. Beyond ensuring optimal use of the index antidepressant, treatment strategies for TRD include switching to another antidepressant, and augmentation or combination with two or more agents. Since little comparative data exist it is important to consider side‐effect burden, partial response, and previous medication history when deciding between strategies. In patients with TRD, adding or augmenting with lithium, tri‐iodothyronine or atypical antipsychotics have demonstrated benefits. Augmentation with atypical antipsychotics, including risperidone, olanzapine, ziprasidone, and quetiapine, show promising results in terms of improving remission rates. Other interventions, including non‐pharmacologic strategies and investigational physical treatments, have demonstrated some benefits, but availability and patient preference should also be considered. With today's therapeutic alternatives, full remission of depression is an attainable goal. For some patients, combination and augmentation strategies earlier in treatment may increase the likelihood of remission.
Cognitive effects of atypical antipsychotics: focus on bipolar spectrum disorders
Authors: MacQueen Glenda , Young Trevor
Published: December 2003

Abstract:  Studies examining cognitive dysfunction in bipolar disorder have documented neuropsychologic impairment in some patients. Recollection memory, attention, and visual information processing may be particularly impaired in patients with bipolar illness. Cognitive impairment appears to worsen with illness progression, and may have a significant impact on function. Pharmacotherapy to treat bipolar disorder including lithium, anticonvulsants, antidepressants, and atypical antipsychotics may have varying effects on cognitive functioning. Treatment with atypical antipsychotics has been associated with improvement in various cognitive measures in patients with schizophrenia, and the little data available in patients with bipolar disorder suggest the potential for similar benefits. Studies to determine if current treatments for bipolar disorder can prevent, delay, or even improve cognitive dysfunction are needed.
Acute and maintenance treatment of bipolar mania: the role of atypical antipsychotics
Authors: Yatham Lakshmi N
Published: December 2003

Abstract:  Bipolar disorder is a complex condition including depression, mania, and in many cases associated with comorbid anxiety symptoms and substance abuse. Mood stabilizers including lithium and divalproex have been considered standard therapy for the treatment of patients with bipolar disorder, but remission rates remain inadequate. Conventional antipsychotics have demonstrated efficacy for acute mania, but they appear to have little role in the maintenance treatment of bipolar disorder. Despite substantial evidence of efficacy and recent guideline recommendations, atypical antipsychotics remain underused for the treatment of bipolar disorder. Data from double‐blind, controlled trials are available for a number of clinically meaningful efficacy measures, including improvement in manic symptoms, onset of action, response rates, remission rates, improvement in comorbid depressive symptoms, and induction/worsening of mania or depression. Atypical antipsychotics are effective both as alternatives to lithium or divalproex as monotherapy, or in combination with these mood stabilizers, in the acute and likely the maintenance treatment of mania. The atypical antipsychotics represent an effective and relatively safe addition to our armamentarium for the treatment of bipolar disorder.