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Identifying the factors that influence the citation of articles helps authors improve the impact and reach of their research. Analysis of publications in the Journal of Fish Biology between 2008 and 2021 revealed that variables such as the number of keywords, abstract length, number of authors, and page length were associated with higher impact papers. These trends applied to both review and regular papers. These findings suggest that papers that are more informative, have higher numbers of authors, and have more keywords are more likely to be cited. Adoption of some simple "best‐practice" behaviors can improve the likelihood that a paper is cited. [ABSTRACT FROM AUTHOR]

In the Indo-Pacific and the Caribbean regions, isolated rivers are host to amphidromous Gobiidae with a life cycle adapted to extreme climatic and hydrological seasonal variation. Although this is the most diverse family of freshwater fish, their biological cycle and the parameters and evolutionary processes that lead to such diversity are poorly understood. This paper reports on the current knowledge on reproduction (nidification, spawning, larval life and sexuality), recruitment into the rivers, upstream migration and distribution in the rivers. Management and restoration strategies to preserve amphidromous gobies, often endemic and bordering on extinction, require the development of research to have a better understanding of their life cycle. [ABSTRACT FROM AUTHOR]

We studied the reproductive strategy, sexual system and growth of dientudo paraguayo Acestrorhynchus pantaneiro. After 2 years of monitoring in shallow areas of a floodplain lake from the lower Paraná basin (Argentina), it was evidenced that water temperature modulated gonadal maturation, but it was the river water level the synchronising stimulus that triggered spawning. This species exhibited a single annual breeding period from October to January, with most spawning activity in November. According to the von Bertalanffy growth curve, fish would reach autumn to winter months with LS of ~120 mm, already mature males. The first mature females were found at LS of 210 mm, becoming sexually mature between the second and third breeding seasons. This is the first integrative study that includes the body‐length frequency distribution and sex differential size at first maturity and growth, and reports the presence of intersex gonads questioning its sexual pattern from gonochoristic to sequential hermaphrodite species. The sexual pattern, the multiple spawning behaviour and a medium to high absolute fecundity support the opportunistic and invasive behavior observed in previous contributions for this characiform species. [ABSTRACT FROM AUTHOR]

This study aimed to describe updated information on the basic reproductive biology of Sphoeroides annulatus females and potential use of the gonadosomatic index IG as input data to assess length at 50% maturity (L50) and identify the breeding season. From April 2014 to December 2015, 767 females were analysed along the north‐west coast of the Mexican Pacific Ocean. Both immature and mature females were represented in the total length (LT), which ranged from 81 to 440 mm, and the smallest mature female was 92 mm (new record for the species). Gonadal maturity phases were assigned through histological analysis. A IG threshold value Icut was established using the lower whisker value for maturity phase spawning capable (2.06%). The monthly variation of IG supported the annual spawning seasonality, and the presence of reproductively active mature females IG≥Icut coincided with the observed periods with histological data and the peaks for both seasons 2014 and 2015. Also the presence of reproductively inactive IG

The present study analysed aspects of reproductive biology based on macroscopic and microscopic structures of whitespotted eagle ray Aetobatus narinari captured by artisanal fishing off the coast of Paraíba and Pernambuco (7° 30′ S, 34° 49′ W; 7° 47′ S, 34° 51′ W), northeast Brazil. Of the 71 individuals in the sample, 55% were female (disc width – WD: 532–1698 mm) and 45% were male (WD: 442–1410 mm). The body size at which 50% of the individuals are mature (WD50) for males was 1155.8 mm; the clasper length varied between 24 and 184 mm. The WD50 for females was 1293.9 mm; the diameter of the largest vitellogenic follicle varied between 11 and 31 mm; and only the left ovary and uterus were functional. The microanatomy of the reproductive tract of males and females agrees with that of other elasmobranch species. In males, the highest hepato‐somatic index (IH) average and gonado‐somatic index (IG) average occurred in the third bimester of the year, whereas in females the highest values (average IH and IG, respectively) were in the second bimester of the year. Based on the information on reproduction of A. narinari from this study, it will be possible to contribute to the correct management and protection of this species. [ABSTRACT FROM AUTHOR]

Osteoglossiformes are an order of "bony tongue" fish considered the most primitive living order of teleosts. This review seeks to consolidate known hypotheses and identify gaps in the literature regarding the adaptive significance of diverse reproductive traits and behaviour of osteoglossiforms within the context of sperm competition and the wider lens of sexual selection. Many of the unusual traits observed in osteoglossiforms indicate low levels of sperm competition; most species have unpaired gonads, and mormyroids are the only known vertebrate species with aflagellate sperm. Several osteoglossiform families have reproductive anatomy associated with internal fertilization but perform external fertilization, which may be representative of the evolutionary transition from external to internal fertilization and putative trade‐offs between sperm competition and the environment. They also employ every type of parental care seen in vertebrates. Geographically widespread and basally situated within teleosts, osteoglossiforms present an effective study system for understanding how sperm competition and sexual selection have shaped the evolution of teleost reproductive behaviour, sperm and gonad morphology, fertilization strategies, courtship and paternal care, and sexual conflict. The authors suggest that the patterns seen in osteoglossiform reproduction are a microcosm of teleost reproductive diversity, potentially signifying the genetic plasticity that contributed to the adaptive radiation of teleost fishes. [ABSTRACT FROM AUTHOR]

The Cephaloscyllium ventriosum shark is present in the artisanal fisheries of elasmobranchs on the western coast of Baja California Sur, Mexico. The main characteristics of the sexual maturation of this species based on individuals captured from off north‐west Mexico in 2013–2016 are described. The size at maturity of this species was determined for the first time (total length 82 cm for females and 76 cm for males). Most females had one egg case per one uterus, and two per one uterus was an isolated event of low incidence. From the histological analysis of females, it was possible to show sperm storage in the oviducal gland. Fully developed sperm in immature organisms were identified in the testes. The main indicator of the maturity stage of males and their mating activity is the clasper. The present study provides evidence for a reliable estimation of the sexual maturity of these organisms, demonstrating the need for the combination of macroscopic and microscopic methods. [ABSTRACT FROM AUTHOR]

The reproductive biology of Pacific hagfish Eptatretus stoutii (Lockington, 1878) and black hagfish Eptatretus deani (Evermann & Goldsborough, 1907) was assessed using current and historical data. Our results found that the reproductive characteristics of both hagfish species reflect those of K‐selected species, which tend to live long and exhibit slow growth rates, low fecundity (approximately 20 eggs per female) and late maturity. Additionally, females of both species commence maturation prior to males. This study provides a population profile for both species of hagfish, but further assessments are needed to effectively manage a sustainable hagfish fishery. [ABSTRACT FROM AUTHOR]

The Rasptail skate Rostroraja velezi is commercially exploited in artisanal elasmobranch fisheries along the west coast of Baja California Sur, Mexico, but information on its life history is limited. This study aimed to investigate the reproductive biology of R. velezi. A total of 105 specimens were caught from April 2008 to May 2012, including the largest reported specimen with 121 cm total length, 96 cm disc width (DW). Females attained larger sizes than males. Males and females presented functional gonads. There was an asymmetry in the testes of males, with the left testis being larger. Histological analysis of the reproductive biology of R. velezi was performed here for the first time. The presence of sperm storage in females and spermatogenic development beginning at the first stages of maturity in males was recorded. It was possible to identify the development of secretions in the club, baffle and terminal zone of the oviducal gland. DW at maturity, defined as the DW at which 50% of the population is mature, was estimated at 68–72 cm for females and 65.1 cm for males. Egg‐bearing females caught in April and May presented one egg capsule per uterus. Furthermore, a description of the egg capsule of R. velezi is provided. Elucidating the reproductive cycle, the type of reproductive strategies, and the fecundity of R. velezi will allow us to understand the impact of fisheries on this species. [ABSTRACT FROM AUTHOR]

This study used data provided by the Chinese Longline Fishery Scientific Observer Programme from the tropical eastern Atlantic Ocean to estimate the reproductive parameters of the blue shark (Prionace glauca) and crocodile shark (Pseudocarcharias kamoharai). Sizes ranged from 80 to 298 cm fork length (FL) for blue sharks and from 48 to 99 cm FL for crocodile sharks. Sexual segregation was observed during different months for both sharks. The sex ratio for blue sharks was 1.38 F:1 M, and 1 F:2.79 M for crocodile sharks. The size of adult blue sharks ranged from 144 to 280 cm for males and from 174 to 298 cm for females; and that of crocodile sharks from 63 to 97 cm for males and 78–99 cm for females. The size at 50% of maturity for blue sharks was estimated at 191.7 cm FL for females and 197.5 cm FL for males, and that of crocodile sharks was assessed at 84.9 cm FL for females and 78.5 cm FL for males. Most sexually matured females were pregnant; their means were 207.2 ± 16.4 cm FL for blue sharks and 89.4 ± 4.3 cm FL for crocodile sharks. Mature sizes for both species were significantly different among months. Embryonic sizes also varied widely among months for crocodile sharks, but a slight change was recorded for those of blue sharks. The observed mean size at birth and litter size were 34.5 cm FL and 37 ± 12 for the blue sharks, and that of the crocodile sharks, 39.5 cm FL and a dominant four embryos in the uterus. Due to the observed increasing catch trend of blue sharks and the slow reproductive cycle of crocodile sharks, this study presents the need of implementing conservation measures to ensure the sustainability of both species in their habitat. [ABSTRACT FROM AUTHOR]

The table of contents for the supplements of the June 2007 issue of the "Journal of Fish Biology" is presented.

To improve understanding of bull shark Carcharhinus leucas reproductive biology, we analysed reproductive traits from 118 bull sharks caught along Reunion Island coasts (Western Indian Ocean), including 16 gravid females. Specific microsatellite loci were used to investigate the frequency of multiple paternity. Males and females reached maturity at c. 234 cm and 257 cm total length (LT), respectively, and litter sizes ranged from 5 to 14 embryos. Analysis of the 16 litters collected in various months of the year indicated that parturition occurs between October and December, with a size at birth c. 60–80 cm LT and that the gestation period is probably c. 12 months. Assuming a 1 year resting period and a period of sperm storage (4–5 months) between mating (in June–September) and fertilisation, the reproductive cycle of bull sharks at Reunion Island would be biennial. At least 56.25% of the litters investigated were polyandrous, sired by 2–5 males. Several males that each sired several litters conceived during the same or distinct mating seasons were detected, suggesting both a seasonal aggregation of sharks to mate and some male fidelity to mating site. Altogether, these findings provide valuable information for both shark risk management and conservation of the species in the Western Indian Ocean. [ABSTRACT FROM AUTHOR]

We compiled historical reports of megamouth sharks Megachasma pelagios (mostly fishery by‐catch and strandings) from 1976 to 2018 (n = 117) and found that they are distributed globally (highest latitude, 36°) with three hotspots: Japan, Taiwan and the Philippines. Despite possible biases due to variability in fishing effort, more individuals were reported at higher latitudes in the summer, suggesting seasonal, latitudinal migrations. Sex ratios were female‐biased in Japan, but more even in Taiwan and the Philippines, suggesting some sexual segregation. Females (total length, LT = 3.41–7.10 m) were larger than males (LT = 1.77–5.39 m) and matured at a larger LT (5.17 m) than males (4.26 m). Also, we reviewed the systematics, feeding ecology and swimming behaviour of Megachasma pelagios based on the literature. Our review shows that, compared with their morphology, anatomy and genetics, behavioural ecology of this species remains largely unknown and electronic tagging studies are warranted. [ABSTRACT FROM AUTHOR]

The article focuses on the improvements and changes on the "Journal of Fish Biology" for the period of 2005. The number of manuscripts submitted had increase by 25 percent from 647 in 2004 to 808 in 2005. For the period of 2006, the 40 percent of reports submitted will be published in the journal and it will be divided into sections such as genetics, taxonomy, biochemistry and immunology. This growth is part of the strategy to retain the periodicals coverage on the field of fish biology.

Daily American eel Anguilla rostrata catches and their dates of passage (starting, median and ending dates) were compared between pristine (1843-1872) and contemporary periods (1963-1990) to determine any changes and see whether these were related to environmental variations and water discharge regulation. Timing and duration of A. rostrata migration patterns differed significantly between the two periods. In the contemporary period, migrating A. rostrata were intercepted significantly earlier than in pristine times (18 days earlier on average), and ended at the same average period. Early A. rostrata migration was also significantly related to high spring flow and secondarily to high spring temperature, while migration ended later when high temperature or low water level occurred during the autumn period. A recent slight increase in the water temperature of the St Lawrence River could partially explain the earlier A. rostrata migration observed during the contemporary period. In return, the effect of high spring flow should have been more contrasted if the river discharge would have not been regulated. Recent A. rostrata production now being mainly restricted to the lower part of St Lawrence River mainstream, resulting shorter travelling distance to the estuary may explain why migrating progress was earlier during the contemporary period. [ABSTRACT FROM AUTHOR]

Three species of hexanchiform sharks belonging to two families and 12 species of squaliform sharks belonging to three families were recorded in fish landing site surveys in eastern Indonesia. Of these, the Squalidae were the most abundant species landed, with Squalus hemipinnis, Squalus edmundsi and Squalus montalbani contributing 0·4, 0·4 and 0·5% to the total number of sharks recorded in a 5 year survey of Indonesian fish landing sites. In comparison, the hexanchid Hexanchus griseus contributed the largest percentage to the total shark biomass. For many species, the majority of the catch consisted of immature fishes, which had not yet been able to reproduce. The data presented in this article are the first biological data reported on most of these shark species and are thus vital for fisheries managers and conservation assessors. [ABSTRACT FROM AUTHOR]

Since haemoglobins of all animal species have the same haem group, differences in their properties, including oxygen affinity, electrophoretic mobility and pH sensitivity, must result from the interaction of the prosthetic group with specific amino-acid residues in the primary structure. For this reason, fish globins have been the subject of extensive studies in recent years, not only for their structural characteristics, but also because they offer the possibility to investigate the evolutionary history of these ancient molecules in marine and freshwater species living in a great variety of environmental conditions. This review summarizes the current knowledge on the structure, function and phylogeny of haemoglobins of notothenioid fishes. On the basis of crystallographic analysis, the evolution of the Root effect is analysed. Adaptation of the oxygen transport system in notothenioids seems to be based on evolutionary changes, involving levels of biological organization higher than the structure of haemoglobin. These include changes in the rate of haemoglobin synthesis or in regulation by allosteric effectors, which affect the amount of oxygen transported in blood. These factors are thought to be more important for short-term response to environmental challenges than previously believed. [ABSTRACT FROM AUTHOR]

The article mentions people that the editors would like to thank for their help in refereeing papers included in the December 2, 2005 issue of the "Journal of Fish Biology."

Lists the reviewers of articles published in the 2005 supplement of the "Journal of Fish Biology". Y. Altukov; E. Beall; J. Beardmore; D. Bekkevold; O.K. Berg.

Courtships sounds and associated behaviours were recorded in the Canestrini's goby Pomatoschistus canestrinii using a simultaneous video–acoustic system: the male exhibited a display composed of both a visual (rapid head movements) and an acoustic component (thump sound), and its intensity was positively associated with that of a female visual display. [ABSTRACT FROM AUTHOR]

Percilia irwini from the Andalién and Biobío River basins of south-central Chile exhibited a mean age of 1·4 years with a maximum age of 4 years. Size at age differed among river zones and males were 10% larger than females at all ages. Compared to other locations, populations of P. irwini inhabiting areas subject to industrial and domestic effluents exhibited smaller size structure. [ABSTRACT FROM AUTHOR]

Stable sulphur isotopic composition (δ34S) of gizzard shad Dorosoma cepedianum was used to investigate the seasonal and ontogenetic variation in the diet of young and adult fish. This study evaluated fish from a hypereutrophic lake that had recently undergone a 40% reduction of large (>300 mm total length, LT) D. cepedianum biomass as part of a biomanipulation experiment, which aimed at reducing internal nutrient loading. Dorosoma cepedianum δ34S values showed evidence of ontogenetic changes with young fish (<200 mm LT) depending more on benthic food sources than adults (>200 mm LT). The δ34S composition of the adult fish suggested an increasing importance of zooplankton in the diet, although benthic food sources remained part of the diet of all D. cepedianum collected in this study. The results indicated that benthic feeding is used by D. cepedianum of all sizes, suggesting that biomanipulation efforts may need to target all sizes of fish to realize benefits. [ABSTRACT FROM AUTHOR]

Editorial. Comments on the adoption of a web-based submission and peer review system called Editorial Manager by the periodical "Journal of Fish Biology." Electronic format of manuscripts; Access to a computer with an Internet connection and a web browser; Completion of review form and comments.

The consequences of date mussel Lithophaga lithophaga harvesting (DMH) on blennioid assemblages was evaluated at Capo Noli-Bergeggi (Savona, north-western Mediterranean Sea) in summer 2005, under the hypothesis that holes bored by L. lithophaga, and left empty by the collection of the bivalve, may represent refuges for these cryptobenthic fishes. Blenniidae and Tripterygiidae were identified to species, and their individuals counted together with the number of empty L. lithophaga holes. The results were compared between ‘impact’ sites affected by the destructive DMH and control sites using two-way ANOVA, and showed that extensive removal of the boring mussels, dramatically increasing the availability of empty holes, favours total number of observed blennioid species and especially Parablennius zvonimiri abundance. [ABSTRACT FROM AUTHOR]

The migratory histories of six Rhinogobius spp., the cross-band type ( R. sp. CB), the large-dark type ( R. sp. LD), the dark type ( R. sp. DA), the cobalt type ( R. sp. CO), the orange type ( R. sp. OR) and R. flumineus, were studied by examining strontium (Sr) and calcium (Ca) concentrations in their otoliths using wavelength dispersive X-ray spectrometry on an electron microprobe. The Sr:Ca ratios in the otoliths changed both with the ontogenetic development and with the salinity level of the habitat. Most fishes had high Sr:Ca ratios around the otolith core in spite of the fact that those fishes live most of their lives in a freshwater environment. The high ratios in the otoliths were thought to be a physiological effect in those fishes. Thereafter, the Sr:Ca ratios changed remarkably along the life-history transect, showing intraspecies and interspecies variations. The otolith Sr:Ca ratios of Rhinogobius sp. CB, R. sp. LD and R. sp. CO collected from three rivers connected to the sea were low around the core, subsequently increased sharply to the points 180–345 μm from the core and then decreased again towards the edge. They were thought to reflect the typical amphidromous life history. The R. sp. CO, however, remain in a brackish-water environment after migration from the sea, while the other species showed typical amphidromous lives with complete freshwater residence after migration from the sea. The five species ( R. sp. CB, R. sp. LD, R. sp. CO, R. sp. DA and R. sp. OR) collected above dams had never migrated to the sea, spending their whole life in a freshwater environment, although Rhinogobius species, except for the fluvial type, were thought to have an amphidromous life history according to previous studies. These species are thought to have a landlocked life cycle. The otolith Sr:Ca ratios of R. flumineus showed consistently low ratios towards the edge except for only around the core, although they were collected from a river connected to the sea. These species could have a fluvial life history corresponding to a previous study. The present study clearly suggests that the migratory histories of Rhinogobius spp. are highly different both within and between species and that they have flexible migratory patterns allowing them to utilize the full range of salinity during their life history. [ABSTRACT FROM AUTHOR]

Rineloricaria isaaci is described from tributaries of the Uruguay River basin in Argentina, Brazil and Uruguay. The new species is distinguished by having a long and wide area of naked skin at the snout tip, surpassing the anteriormost pore of the infraorbital ramus of the sensory canal, approximately in the middle of the third postrostral plate, and by its particular sexual dimorphism characterized by the long pectoral and pelvic fins of mature males. [ABSTRACT FROM AUTHOR]

Age and total length ( LT) at maturity of allis shad Alosa alosa exhibited a significant negative latitudinal gradient over the species’ distribution range. Particular thermal conditions experienced over the distribution area could be the key factor involved to explain this negative trend. [ABSTRACT FROM AUTHOR]

Rapid decreases in water temperature may result in a number of physiological, behavioural and fitness consequences for fishes termed ‘cold shock’. Cold-shock stress occurs when a fish has been acclimated to a specific water temperature or range of temperatures and is subsequently exposed to a rapid decrease in temperature, resulting in a cascade of physiological and behavioural responses and, in some cases, death. Rapid temperature decreases may occur from either natural ( e.g. thermocline temperature variation, seiches and storm events) or anthropogenic sources ( e.g. varied thermal effluents from power generation and production industries). The magnitude, duration and frequency of the temperature change as well as the initial acclimation temperatures of individuals can influence the extent of the consequences of cold shock on fishes. Early research on cold shock focused on documenting mortality events associated with cold shock. However, in recent years, a shift in research has occurred where the focus of cold-shock studies now involves characterizing the sublethal effects of cold shock in terms of the stress response in fishes. This shift has revealed that cold shock can actually be used as a tool for fisheries science ( e.g. to induce polyploidy). The cold-shock stress response offers opportunities to develop many exciting research questions, yet to date, cold-shock research has been largely unfocused. Few studies attempt to link laboratory physiology experiments with ecologically relevant field data on behaviour, growth, bioenergetics and fitness. Additional research will allow for the development of more focused and robust management policies and conservation initiatives. This review synthesizes the sublethal physiological and behavioural consequences of cold-shock stress on fishes, identifies natural and anthropogenic sources of cold shock, discusses the benefits of cold shock to fisheries science and describes mitigation and management efforts. Existing knowledge gaps and opportunities for future cold-shock research are presented. [ABSTRACT FROM AUTHOR]

This study shows how capture–mark–recapture (CMR) models can provide robust estimates of detection heterogeneity (sources of bias) in underwater visual-census data. Detection biases among observers and fish family groups were consistent between fished and unfished reef sites in Kenya, even when the overall level of detection declined between locations. Species characteristics were the greatest source of detection heterogeneity and large, highly mobile species were found to have lower probabilities of detection than smaller, site-attached species. Fish family and functional-group detectability were also found to be lower at fished locations, probably due to differences in local abundance. Because robust CMR models deal explicitly with sampling where not all species are detected, their use is encouraged for studies addressing reef-fish community dynamics. [ABSTRACT FROM AUTHOR]

People that the author would like to thank for their assistance in the creation of his book are mentioned.

Although the unique features of asexual reproduction and hybridization among European spined loaches (genus Cobitis) have recently attracted the attention of conservation biologists, faunists and evolutionary biologists, the research has suffered from uncertain identification of specimens and their genomes because of the extreme morphological similarity of all the species within the hybrid complex. In this article, a Europe-wide study is reported, which was performed on samples collected by several research teams. Several complementary methodologies, such as allozyme analysis, karyotyping, flow cytometry and DNA sequencing allowed us to confirm or reject the existence of all previously reported species and their hybrids as well as to uncover several new hybrid biotypes. The biogeography of all the known biotypes, that is, parental species and hybrid biotypes, has been summarized here and the taxonomic position of two undescribed putative species mentioned in previous publications has been established. New polymerase chain reaction restriction fragment length polymorphism markers for species determination have further been developed and applied, which would allow the unambiguous identification of parental species and their genomes in the known hybrid biotypes within the complex. [ABSTRACT FROM AUTHOR]

The seasonality, size, age, colour phases and sexual dimorphism of 13 reproductive classes of hogfish Lachnolaimus maximus are described. Analysis of histological sections of gonads ( n = 1662) confirmed earlier conclusions that L. maximus is a monandric, protogynous hermaphrodite. Sex change was initiated at the end of the spawning season and over a broad range of sizes and ages. It occurred after a functional female phase (postmaturation) and proceeded more slowly (months) than previously believed. Eventually all individuals changed sex to a terminal male phase. Females were batch spawners, spawning as often as every day during winter and spring. There was no evidence of precocious sperm crypts in active females, sperm competition or other alternative male sexual strategies. Mating has been reported elsewhere to be haremic. The sexual development of L. maximus appears to be adaptive in terms of Ghiselin’s size-advantage model, which links monandric protogyny and polygyny. The slow rate of sex change, however, poses problems when fishing pressure is high because harvest of a single male has the potential to reduce the reproductive output of an entire harem. [ABSTRACT FROM AUTHOR]

Visible implant elastomer (VIE) tagging showed no significant effect on survival of either 230 single-tagged or 60 multiple-tagged small European eels Anguilla anguilla. Mean tag retention was 98·7% during the 5 month laboratory experiments. Multiple VIE tags had no observed effect on European eel locomotor behaviour. VIE appears a reliable method for individually tagging small European eels, and could be useful in capture–recapture field studies. [ABSTRACT FROM AUTHOR]

Gudgeon Gobio gobio (Cyprinidae) were collected monthly from the Vlara Stream (Czech Republic) during 2004 and examined for the presence of the ectoparasite Paradiplozoon homoion (Diplozoidae; Monogenea). Over 26% of P. homoion showed abnormalities of the attachment sclerites, indicating either a stressful environment or that the quality of the fish host was suboptimal for parasite development. Here, the hypotheses that parasite abundance and the occurrence of morphological abnormalities are correlated with fluctuating asymmetry (FA, the random deviation from the perfect bilateral symmetry) in its fish host were tested. The FA and morphological abnormality are estimators of developmental instability. To estimate fish developmental instability nine meristic and two morphometric bilateral characters on the right and the left sides of the fish were measured. In general, there was no correlation between mean fish FA and parasite abundance or the proportion of parasites with abnormalities. There was, however, a significant relationship between the proportion of abnormal P. homoion and the number of asymmetric meristic traits per individual fish. This study thus indicates that developmental instability of P. homoion, measured as morphological abnormality of the attachment apparatus, is only weakly dependent on the fish quality as measured by FA. [ABSTRACT FROM AUTHOR]

Details of the reproductive biology, size and age compositions and growth of the breaksea cod Epinephelides armatus, the sole representative of Epinephelides, were obtained by collecting monthly samples of a wide total length ( LT) range of individuals from coastal marine waters at 31–32° S on the lower west coast of Australia. Although the modal LT class of females (250–299 mm) was markedly less than that of males (400–449 mm), the modal ages of the two sexes were similar, i.e. 4 v. 5 years, respectively. The similarity in the age compositions and the histological demonstration that the gonads of all E. armatus consist solely of either ovarian or testicular tissues demonstrate that this species is gonochoristic, which is highly unusual for an anthiinine serranid. The absence of a central, membrane-lined ‘ovarian’ lumen in the testes of juveniles would account for adult testes containing neither this ovarian remnant nor the peripherally located sperm sinuses that are found in the mature testes of almost all other serranids. The results demonstrate that E. armatus exhibits a very unusual pattern of sexual development for a serranid. The spawning period of E. armatus lasts for c. 9 months, which is long for a species in temperate Western Australian waters, but comparable with that of many other relatively small serranids elsewhere. Females grow slower than males, attaining LT at 3, 5 and 10 years of c. 200, 285 and 420 mm, respectively, compared with c. 215, 315 and 450 mm, respectively. Females, however, attain maturity at a greater LT and older age than males. [ABSTRACT FROM AUTHOR]

Trace element and fork length ( LF) frequency analyses of eulachon Thaleichthys pacificus otoliths were used to determine age at maturity and repeat spawning potential, two aspects of eulachon life history that are not known but are important for successful management of this species. The LF-frequency analysis for ocean caught and spawning eulachon was used to estimate age at maturation. Two size classes of eulachon were caught in the ocean and spawning eulachon were consistently the largest fish indicating that spawners from mid-coast of British Columbia were 3 years old. Laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) was also used to reconstruct the Ba:Ca and Sr:Ca molar ratios deposited spatially into the otolith to estimate spawner age for five populations of eulachon. Age at maturation differed among populations examined. Based on the seasonal fluctuations in Ba:Ca molar ratios caused by seasonal upwelling of deep waters, it was determined that more southerly populations spawned at a younger age than the northern populations examined. Southern populations of eulachon, Columbia River, Washington, U.S.A., spawn after 2 years. Eulachon from the Fraser, Kemano and Skeena Rivers in British Columbia, Canada, generally mature after 3 years. Some Skeena River eulachon and most of the eulachon from the Copper River, Alaska, U.S.A., matured after 4 years. In contrast to the Ba:Ca molar ratios in the otolith, Sr:Ca molar ratios maintained a relatively flat profile over the life of the eulachon. The lack of a change in Sr:Ca ratios within the otolith, the single size class of spawners across all systems and the single age class within most populations strongly suggest that eulachon in the present study are semelparous. [ABSTRACT FROM AUTHOR]

The first detailed information on the biological aspects of members of the economically important shark family Carcharhinidae in Indonesian waters is given. Carcharhinids dominated the landings of sharks at sites visited, comprising almost 60% of the total biomass of all sharks recorded, over an intensive 5 year sampling period. A total of 26 species of carcharhinids, representing half of the species in the Carcharhinidae, were recorded. The most abundant species, in terms of numbers recorded, were Scoliodon laticaudus and Carcharhinus falciformis, while the most abundant in terms of biomass were Prionace glauca, C. falciformis and Carcharhinus obscurus. Biological data are presented for 22 of the 26 species. The total length at which males attain maturity ( L50) was determined for 10 species. The biological aspects of a number of species, most notably Carcharhinus sorrah and Loxodon macrorhinus, were found to differ from those recorded in the literature for other regions. [ABSTRACT FROM AUTHOR]

The miniature cyprinid fish, Sundadanio axelrodi, exhibits extreme sexual dimorphism in the skeleton of the Weberian apparatus, the fifth rib and pectoral girdle. Musculature associated with the fifth rib and Weberian apparatus also shows a high degree of sexual dimorphism. It is suggested that these modifications are responsible for the production of a croaking sound that seems to be restricted to males of the species, based on the lack of any corresponding anatomical specializations in females. [ABSTRACT FROM AUTHOR]

Variation at seven microsatellite loci was compared with variation observed at Pan I, a single copy nuclear DNA gene coding for pantophysin, in 14 samples of Atlantic cod ( Gadus morhua) stretching from Spitsbergen to the North Sea. Population structuring indicated by the two types of markers was concordant and in agreement with the traditional grouping of cod in the study area into three main populations: north-east Arctic cod (NEAC), Norwegian coastal cod (NCC) and North Sea cod (NSC). Microsatellites, however, revealed genetic heterogeneity not only within NCC, as did Pan I, but also within NEAC and NSC, which appeared to be homogenous when analysed for Pan I. Moreover, microsatellites displayed lower levels of differentiation than Pan I between NEAC and two other groups. Differences in the magnitude of differentiation for the two types of markers may be attributable to higher levels of polymorphism and alleged selective neutrality of microsatellites. Isolation by distance was clearly apparent for microsatellites but was less evident for Pan I, indicating that environmentally induced selection appears to shape the patterns of genetic differentiation for this marker. Even though the population structure of north-east Atlantic cod, as revealed by microsatellites and Pan I, appears to be maintained largely by restricted gene flow, selection acting on a recent historical time scale probably contributes to the observed geographic pattern of Pan I frequencies. [ABSTRACT FROM AUTHOR]

The occurrence of golden galaxias Galaxias auratus with dermal fungal lesions in two populations was effectively modelled by the progression of gonadal stages of development. Skin lesions were found to be characteristic of fungal dermatitis and a Saprolegnia sp. was identified as the causative agent. Infection is probably linked to spawning-related factors and it is probable that saprolegniasis is associated with seasonal mortality. [ABSTRACT FROM AUTHOR]

The occurrence of Opeatogenys gracilis outside the Mediterranean Sea is confirmed for the first time. This is probably a more common species than previously thought, but its apparent complete dependence on seagrass beds suggests the possibility of including it in the IUCN threatened species list. Some sex differences are described and a complete meristic and morphometric description of the species is presented. The occurrence of the species in the north-east Atlantic indicates that it might be a recent dispersal from the Mediterranean Sea, or an overlooked part of the autochthonous fauna. [ABSTRACT FROM AUTHOR]

Atypical pigment was observed in pre-flexion, flexion and post-flexion larval Sebastes collected off central California in 1991 and 1992 that otherwise resembled Sebastes jordani. Atypical pigment occurred on the axillary region at the base of the pectoral fin (most prominent on the inner edge of the pectoral fin base adjacent to the gut), on the median and distal regions of the pectoral fin and on the median and distal regions of the pelvic fin. In addition, lower and upper jaw pigment was observed at a much smaller size in these specimens than previously described in the literature. Identifications of these atypical specimens as S. jordani were confirmed using meristic and otolith characters as well as mitochondrial DNA sequence data. The ontogenetic variability of S. jordani is described. Specimens collected north of Point Conception were more pigmented than larval S. jordani described in the literature (collected predominately south of Point Conception), suggesting geographic variation in pigment development during the larval stage. [ABSTRACT FROM AUTHOR]

The responsible approach to marine stock enhancement is a set of principles aimed at maximising the success and benefits of artificially re-stocking depleted fisheries. The benefits of such an approach are evident in the 400% increase in survival of stocked striped mullet in Hawaii through refinement of release techniques, however financially or temporally constrained stocking programs in Australia have not adhered to all principles. A pragmatic approach to address these principles is proposed, using international examples and Australian marine finfish pilot stockings of barramundi, mulloway, sand whiting, dusky flathead and black bream. Biological ranking of candidate species by estuarine residency, a low natural-mortality to growth ratio, a large L∞ and comparison by recreational value and available rearing technologies, show that mulloway, barramundi and sea mullet are ideal species for stocking in Australia. Australian intermittently closed opening landlocked lagoons and recreational fishing havens, especially near cities, provide experimental opportunities to apply this approach and stock suitable species through small-scale pilot experiments. This would allow evaluation of production and carrying capacity, and density dependent processes with respect to optimal stocking strategies unconfounded by emigration and commercial fishing practices. Twenty per cent of Australians fish each year, and harvest approximately 27 000 t of finfish. Stocking recreationally important species in Australia should give a greater financial benefit, which is spread across a larger cross-section of the community, compared to stocking to enhance commercial fisheries. The pragmatic application of the responsible approach, and stocking of fast growing estuarine residents into recreational fishing havens would enhance the benefit from marine stocking. [ABSTRACT FROM AUTHOR]

The common smelt is one of the most widespread indigenous freshwater fishes in New Zealand. One other member of the family Retropinnidae,Stokellia anisodon(Stokell), is present but is confined to a small region of the South Island. There are many diadromous as well as river and lake resident populations, the latter, sometimes a result of introductions to serve as forage fish for trout. Diadromous smelt spawn during austral autumn–winter on sand bars of lower riverine reaches. Larval stages inhabit coastal marine waters, and the postlarvae to immature stages re-enter rivers and some lowland lakes. Diadromous smelt are distinguished from lowland lake resident forms by high vertebral but low gill raker numbers and larger size and from those present in some isolated waters, by high vertebral numbers alone. Lake or reservoir resident smelt usually spawn in austral spring–summer on sandy shallows at stream mouths or along shorelines. Verified smelt ages(otolith analyses) indicate that in some populations most smelt mature and spawn afterc.1 year. Adult smelt feed on a spectrum of primarily invertebrate animals ranging from small zooplankters to insects and occasionally small fishes. Smelt are a major prey for both brown trout and rainbow trout. Adult smelt are a minor food for the Maori people. As postlarvae they are a component of a few‘whitebait’ fisheries. Most smelt populations are increasingly affected by environmental changes induced by human activities. Although many studies have examined problems affecting smelt, further effort is required, along with more basic research. [ABSTRACT FROM AUTHOR]

The reproductive biology of blacknose sharks Carcharhinus acronotus in the western North Atlantic Ocean was studied by examining specimens collected in the coastal waters of South Carolina. Males begin the maturation process between 875 and 910 mm fork length ( LF), as indicated by the presence of functional claspers and siphon sacs. The presence of vitellogenic oocytes and developing oviducal glands and uteri indicated that females begin to mature at c. 870 mm LF. Length at which 50% of the population reached maturity was 896 and 964 mm LF, equivalent to 4·3 and 4·5 years, for males and females, respectively. Gonado-somatic indices suggested that spermatogenesis and vitellogenesis began after December. Mating took place during the end of May and the beginning of June. Fertilization occurred during late June and early July, suggesting that female blacknose sharks were capable of sperm storage. Based on the timing of fertilization and occurrence of females carrying near-term pups in late May and early June, the gestation period for blacknose sharks was c. 11 months. Female blacknose sharks reproduced biennially based on the absence of vitellogenic oocytes in near-term females and there being no indication of vitellogenesis in postpartum females. Male blacknose sharks were capable of reproducing annually as indicated by turgid genital ducts, which were observed in all mature males collected during late May and early June. [ABSTRACT FROM AUTHOR]

One specimen of the largetooth cookiecutter shark Isistius plutodus was caught in the north-eastern Atlantic at 43°58′ N; 28°32′ W. This is the first record of this rare species in the north­eastern Atlantic and the northernmost point of its known distribution. [ABSTRACT FROM AUTHOR]

Intensely displaying sand goby Pomatoschistus minutus males had lowerlipid content, indicating that signalling increased energy expenditure, or that low condition males increased their signalling effort. Display intensity correlated positively with nest-defence and tended to correlate positively with filial cannibalism. [ABSTRACT FROM AUTHOR]

The osmolality and ionic composition of the blood of juvenile Atlantic cod Gadus morhua and their response to conditions of reduced temperature and salinity in summer- and winter-acclimated individuals was investigated. Haematocrit percentage was relatively stable throughout the experimental procedures. Summer-acclimated juvenile Atlantic cod had higher plasma osmolality than winter-acclimated fish in ambient conditions. Plasma Na+ levels were, however, higher in winter conditions, while Cl- did not vary between seasons. Temperature reduction (12, 9 and 6° C in summer and to 6 and 4° C in winter) induced a significant response in plasma osmolality and Na+ levels in summer, but only in Na+ levels in winter-acclimated fish. A pronounced effect was seen in the summer 6°C treatment. Salinity treatments (24, 16 and 8) had a significant effect on almost all the variables in both summer and winter and resulted generally in dilution of ionic and osmotic concentrations of the plasma. This effect was pronounced in the lowest temperature treatments, with the greatest reduction observed in the summer 6°C treatment. This could suggest that winter-acclimated fish are physiologically adapted to cope with lower seawater temperatures as opposed to summer-acclimated fish. [ABSTRACT FROM AUTHOR]