Eradicating the invasive topmouth gudgeon, Pseudorasbora parva, from a recreational fishery in northern England

Abstract  An established population of the invasive topmouth gudgeon, Pseudorasbora parva (Temminck & Schlegel), was discovered in a recreational fishery in Northwest England in 2002. As the lake was seasonally connected to a river catchment, providing potential for dispersal, a containment and eradication programme was initiated. Containment involved screening of outfalls and preventing fish movements off site. Eradication involved the fishery being treated twice with a rotenone-based piscicide, in March and April 2005. The mean P. parva density prior to rotenone application was 6.1 m⁻²; following the application, none were recorded. Non-target species in the fishery were removed prior to the application; following rotenone degradation, they were re-introduced and subsequently spawned, with recording of young-of-the-year. This contrasts with 2004 when only young-of-the-year of P. parva were recorded. As the eradication appeared to be successful, the method is considered suitable for use on other populations posing a similar threat of dispersal of the species into rivers and on other invasive fish populations in undesirable locations.     

Case studies on eradicating the Asiatic cyprinid Pseudorasbora parva from fishing lakes in England to prevent their riverine dispersal

• 1. The topmouth gudgeon Pseudorasbora parva has proved to be a highly invasive pest fish species in mainland Europe following introduction from Asia, and was first recorded in the wild in the UK in 1996. Distribution has increased markedly since 2002, with recordings now from 32 sites, the majority being lakes.
• 2. In infested UK lakes, populations establish rapidly and become dominant in the fish community (often >97% by number); densities to over 60 m^?2 have been recorded, with the majority of individuals <70 mm. The species also hosts a novel pathogen not previously recorded in the UK. It has, therefore, been identified as a significant concern to native fish communities and deserving of an appropriate response by regulatory authorities.
• 3. Where populations have been detected in lakes with connection to river catchments, actions have been taken to prevent riverine dispersal. Control measures are put in place, and eradication programmes designed and initiated. This paper details case studies on three completed eradication operations, two that utilized the piscicide rotenone, the other, de‐watering and disinfection.
• 4. Each case study has, so far, been successful in eradicating the topmouth gudgeon population and has resulted in approximately 280 km of river length being protected from their dispersal. Application of rotenone was the most cost‐effective eradication method at approximately £2 per m² of water area treated.
• 5. These case studies demonstrate that riverine dispersal of invasive fish from infested connected lakes can be prevented by eradication. Outputs can be used to develop a strategy to manage the increasing distribution of topmouth gudgeon—and other invasive, pest fish—in the UK.

Copyright © 2008 John Wiley & Sons, Ltd.     

Pan‐continental invasion of Pseudorasbora parva: towards a better understanding of freshwater fish invasions

In recent years, policy‐makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non‐target species that are unknowingly released alongside intentionally‐introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan‐continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits.     

Reintroduction of a native galaxiid (Galaxias fasciatus) following piscicide treatment in two streams: response and recovery of the fish population

The rehabilitation of native communities by means of eradicating unwanted fish species using piscicides is an example of employing disturbance to achieve conservation successes. Such projects provide a valuable opportunity to test the efficiency of the tool and the impacts on the receiving aquatic communities, as disturbance occurs at a known time. The piscicide ‘rotenone’ has been widely used to eradicate invasive or unwanted fish species worldwide. However, there is little information regarding the impact on native fish being reintroduced to a stream after rotenone treatment. The mass depletion of aquatic invertebrates due to rotenone dosing is of particular concern, as food‐limitation could negatively impact on fish growth, condition and recruitment, compromising the aims of rehabilitation. For the first time in New Zealand, rotenone was employed to eradicate brown trout (Salmo trutta) from two streams that also supported populations of banded kokopu (Galaxias fasciatus). Impacts on fish and aquatic invertebrates were studied in two treatment and two reference streams in Karori, Wellington. Analysis showed that invertebrate densities declined significantly in the treatment streams in the 2‐week to 2‐month period after dosing. Following reintroduction after rotenone treatment, banded kokopu condition declined significantly and levels of fish mobility were variable. One year after rotenone dosing, there was recruitment of banded kokopu juveniles in the treatment streams indicating successful reproduction, with no equivalent increase in the reference streams. Results are a positive indication for the use of rotenone as an effective conservation tool to remove unwanted fish species where they threaten native populations.     

Use of Rotenone as Piscicide: Toxicity Levels in a Few Common Freshwater Predatory and Weed Fishes

Toxicity of rotenone was studied in a few common freshwater predatory and weed fishes through wet laboratory experiments for its use as a piscicide during pond preparation. Cube root powder (CRP) (ENT-133 Rotenone) containing 9% rotenone was used as the toxicant source. Lethal concentration of CRP for these common predatory and weed fishes varied between 0.75–2.70 mg L^?1 (0.068–0.243 mg L^?1 of rotenone). Acute toxicity study revealed Puntius sophore to have more susceptibility to rotenone toxicity with 24 h LC₅₀ value of CRP at 0.50 mg L^?1 (0.045 mg L^?1 rotenone) compared to 1.17 mg L^?1 (0.105 mg L^?1 rotenone) in Anabas testudineus and 1.90 mg L^?1 in Channa punctatus (0.171 mg L^?1 rotenone); while Heteropneustes fossilis showed higher tolerance with 24 h LC₅₀ value at 2.42 mg L^?1 (0.218 mg L^?1 rotenone). Such result suggested rotenone toxicity to depend on the respiratory behavior of fish. The marginal reduction in 48 h LC₅₀ of CRP compared to its 24 h value and no fish mortality beyond 48-h in all tested species suggested faster degradation of the toxicant in water. Since application of the piscicide aims at eradication of all commonly available species of predatory and weed fishes in the culture pond, the study suggested a dose of 2.5 mg L^?1 of CRP (0.225 mg L^?1 rotenone) for pond application.     

The Welsh Torgoch (Salvelinus alpinus): a short review of its distribution and ecology

Abstract –  The Arctic charr Salvelinus alpinus (L.), or Torgoch ('red belly') in Welsh, is found in seven lakes in North Wales comprising three native populations (Bodlyn, Cwellyn and Padarn) and four translocated populations (Cowlyd, Diwaunedd, Dulyn and Ffynnon Llugwy). The Welsh charr populations have not been studied much, but the available data are summarised in this short review. Analysis of stomach contents of the native charr populations shows that they are planktivores feeding mainly on cladocerans and copepods. Adult fish attain a size of 14–24 cm (fork length) and fecundity is low (100–800 eggs per female). The available growth data reveal that Welsh charr grow at a similar rate and attain a size similar to most other planktivorous charr populations that have been studied in the UK. Genetic studies using allozymes indicate that the three native populations are distinct from each other.     

入侵种麦穗鱼的形态特征分析

研究不同生境条件下入侵种的形态差异是了解生物入侵的重要手段。运用多变量形态度量学和框架结构形态学方法,测量了采自四川南充、石棉、茂县和西昌共4个不同栖息地的94尾麦穗鱼(Pseudorasbora parva)标本,在双筒解剖镜下检视,采用电子数显游标卡尺测量了侧线鳞、侧线上鳞、侧线下鳞以及背鳍、胸鳍、腹鳍、臀鳍的分枝鳍条共7个可数性状。应用多变量形态度量学方法,选择18个框架结构性状和16个常规性状进行主成分分析。结果表明,3个主成分的累计贡献率达到76.59%,4个不同地点的标本聚在一起没有分开,表明入侵种麦穗鱼各居群间的形态没有显著差异。结合文献资料分析了麦穗鱼入侵的原因,指出了在进行经济鱼类引种过程中,应针对麦穗鱼制定有效地管理措施,实行早期的监测和预警系统,防止麦穗鱼的卵、苗种和幼鱼等人为侵入;已发现的麦穗鱼应该及时处理,避免其在引入地进一步扩散;对于已经在引入地建立了自然种群的麦穗鱼,应该根据生物学原理(如生理、生态因子的耐受性、食性、繁殖特性、寄生虫感染等)进行综合治理,使其对土著鱼类的危害处在可控范围之内。     

Occupancy dynamics of rare cyprinids after invasive fish eradication

1. The eradication of invasive species is a management strategy implemented to eliminate adverse impacts of invaders on native species communities. After eradications, follow‐up studies are done to confirm eradication of the invasive species and the short‐term recovery of the native species, but long‐term monitoring to confirm full population recovery and stability is often not completed.
2. In this study, long‐term monitoring of native fishes was carried out over 5 years after the eradication of an invasive fish from the Rondegat River, South Africa. Forty‐six sites distributed along four river sections were sampled for presence/absence using underwater cameras and snorkel surveys. Density data were collected by snorkel surveys.
3. Using multi‐season occupancy models, the annual probability of colonization and local extinction of the native fishes and annual rate of change in occupancy along the river were estimated. Changes in native fish densities across time and across the control and treatment sections were analysed using Kruskal–Wallis analysis, followed by Dunn's post‐hoc test.
4. Probability of colonization and local extinction differed for each native fish species and may have been affected by extrinsic factors, such as rainfall, and intrinsic density‐dependent factors, hypothesized from the density data. The occupancy rates of change revealed that the two Near Threatened fish species have reached an occupancy dynamic equilibrium but the Endangered fish has not, suggesting that other conservation efforts may be needed.
5. Long‐term monitoring of native fishes after an eradication programme has confirmed the successful removal of the invader and the recovery and stability of the community. However, successful eradication was not sufficient for full recovery of all species; additional conservation management strategies are needed to secure the population stability and persistence of endangered fishes. We recommend that eradication programmes, regardless of locality, should employ long‐term monitoring to ensure full recovery of a native fish community.

     

Inhibition of sexual maturation in tank reared haddock (Melanogrammus aeglefinus) through the use of constant light photoperiods

The haddock (Melanogrammus aeglefinus) is believed to be a potential candidate for aquaculture in the Atlantic coastal countries including the UK, Norway and Canada. However, under culture conditions, haddock will sexually mature prior to the attainment of a suitable harvest weight. Therefore, a long term tank based experiment was performed where three populations of haddock (hatched spring 2002, approximately 150 fish per population) were exposed to either a simulated natural photoperiod (SNP) or SNP until January or July 2003 and thereafter continuous illumination (Jan LL or July LL respectively) with individual growth rate and maturation status being recorded until July 2004 (27 months post-hatch). While the SNP treated population matured in the spring of 2004 (two years post-hatch) with 88% of the population being observed to release gametes, no mature individuals were observed in either of the LL treated populations and furthermore there was no evidence of gonadal development or elevation in sex steroids (testosterone, estradiol-17β or calcium). The application of LL appeared to directly stimulate the growth rate of haddock (e.g. 14 to 27% increase in weight thermal growth coefficient) and improve food conversion rates. At the end of the trial there was an approximate 50% increase in wet weight (SNP: 647 ± 53 g, Jan LL: 982 ± 34 g and July LL 985 ± 33 g), however no significant difference in weight in relation to the length of LL exposure was observed. Plasma melatonin analysis revealed that the natural diel rhythm had been inhibited in both LL treated populations. Along with highlighting the similarity in reproductive entrainment between haddock and other gadoids, these results demonstrate how photoperiod manipulation could be used as a management strategy to improve growth performance in farmed haddock stocks.     

Tagging effects on three non-native fish species in England (Lepomis gibbosus, Pseudorasbora parva, Sander lucioperca) and of native Salmo trutta

Abstract –  To address the dearth of information on tagging effects and long-term survivorship of tagged fish in native and introduced species, laboratory and field investigations were undertaken on three non-native fish species (pumpkinseed Lepomis gibbosus ; topmouth gudgeon Pseudorasbora parva ; pikeperch Sander lucioperca ) tagged with coded-wire (CW), passive integrated transponder (PIT), radio (RT) telemetry and/or acoustic tags (AT), with survivorship of native brown trout ( Salmo trutta ) examined in the field. Laboratory results revealed high survivorship following tag attachment/insertion and resumption of feeding within 24–48 h of tagging (all mortalities could be attributed to an unrelated outbreak of fungal infection), with retention rates being high in both pumpkinseed and pikeperch but low in topmouth gudgeon (excluded from field studies). In the field, short-term post-operation survival was high in pikeperch, pumpkinseed and brown trout. In pumpkinseed and trout, 100% of RT fish survived a 24–30 day tracking study, with 60% and 80%, respectively, recaptured alive at least 3 months post-tagging. Of PIT tagged pumpkinseed, 44% were recaptured (after 6–18 months), with small-sized, CW-tagged fish (0.38 g weight) captured up to 1 year after tagging. In pikeperch, all AT fish except one (the smallest specimen) survived their full expected tracking period (i.e. tag life) – the single lost specimen survived at least half of its expected tracking period (i.e. 6 month battery life). Overall, the tagging methods used were highly effective in pumpkinseed and pikeperch, showing good retention and survival, but PIT tagging of topmouth gudgeon was plagued by low survivorship and tag rejection.     

Fish feeding in changing habitats: effects of invasive macrophyte control and habitat complexity

Abstract –  Many freshwater lakes have been invaded by non-native aquatic plants. Although managing the invasions is necessary to restore native macrophytes, little is known about the effects of invasive macrophyte eradication on fish foraging. This study was designed to determine whether fish feeding was affected by large-scale changes in plant composition after selective control of invasive Eurasian watermilfoil, Myriophyllum spicatum , and whether feeding was correlated with habitat complexity or abundance of invasive plants on a smaller scale. Popnets were used to collect plants, invertebrates and fishes in the littoral zone of four Minnesota lakes twice a year for 4 years. The degree of stomach fullness in fishes was not correlated with the proportion of invasive plants or habitat complexity. Bluegills, the most abundant fish species, exhibited high selectivity for Diptera and their preferences varied little in different plant habitats. Changes in niche width of bluegills were not consistent with invasive plant control. Overall, invasive macrophyte control with timely restoration of the native plant community did not affect the characteristics of fish feeding we investigated. This study also contributes to our understanding of fish–macroinvertebrate interactions as a function of habitat complexity.     

Red swamp crayfish,Procambarus clarkii,found in South Africa 22 years after attempted eradication

1. No freshwater crayfish are indigenous to continental Africa, but four species have been introduced to the continent. One of these is the North American red swamp crayfish Procambarus clarkii, which has been introduced into several African countries, mainly for aquaculture, and has had demonstrable impacts where it has escaped captivity. In South Africa, the documentation of this species in farm dams near Dullstroom and the adjacent Crocodile River in 1988 resulted in an eradication attempt in 1994, with unknown results. 2. In order to evaluate the status of P. clarkii in South Africa, dams on the previously invaded farm and the Crocodile River were sampled four times between December 2015 and June 2016 using visual surveys, trapping, dipnetting and electrofishing. This yielded a single reproductively active male P. clarkii from one of the farm ponds, while many other native aquatic species were found in high numbers. 3. It is clear from this study that P. clarkii was not eradicated in South Africa and that individuals have been surviving in the wild (i.e. outside captivity or cultivation) for at least 28 years in the location where it was introduced. Containment and eradication of the species are proposed as management actions, which have major importance in preventing undesirable further spread or translocation of this species into new aquatic environments in South Africa.     

Managing non‐native fish in the environment

Non‐native fishes are frequently used to enhance aquaculture and fisheries; if introduced into the wider environment, then the majority will have negligible effects on native biodiversity. However, a minority will become invasive, causing adverse ecological effects, and so management actions may be needed to minimize their dispersal and impacts. These actions include eradication attempts from specific waters or well‐defined spatial areas, population control by suppression (e.g. through removal programmes) and containment of existing populations to prevent their further spread. These remedial actions have generally only been undertaken across large spatial areas in developed countries; experience suggests a fundamental constraint is a lack of selective removal methods that target the non‐native fish species only. For example, eradication methods tend to be limited to low technology, ‘scorched‐earth’ techniques (e.g. biocide chemicals) whose use is generally constrained to relatively small and enclosed water bodies. Risk management of non‐native fishes should ensure that actions taken are commensurate with the level of risk posed by that species in the environment; although pre‐introduction risk assessment schemes have been developed, there remains a lack of decision support tools for post‐introduction situations. Although this inhibits the management of non‐native fishes in the environment, control programmes such as those against common carp Cyprinus carpio in Australia and topmouth gudgeon Pseudorasbora parva in England and Wales suggest there is potential for invasions to be managed and controlled within large spatial areas, even if their eradication may not be feasible.     

Species identification of <Emphasis Type="Italic">Pinctada imbricata</Emphasis> using intergenic spacer of nuclear ribosomal RNA genes and mitochondrial 16S ribosomal RNA gene regions

ABSTRACT:   For pearl production, pearl oyster seeds from foreign pearl oysters as well as hybrids between native and such foreign pearl oysters are produced in Japanese hatcheries. However, it is very difficult to identify these pearl oysters and hybrids based on morphological measurements. Thus, a molecular identification method for distinguishing Atlantic pearl oysters Pinctada imbricata from the Indian-Pacific pearl oyster group including P. martensii and P. fucata , was developed. The polymerase chain reaction (PCR) products of the partial intergenic spacer (IGS) of nuclear ribosomal RNA (rRNA) genes exhibited length polymorphism between P. imbricata (590 bp) and the other two species (427 bp). The restriction fragment length polymorphism analysis of the PCR products (PCR-RFLP) cleaved with Mse  I observed in the IGS of nuclear rRNA genes also gave different profiles between P. imbricata and the other two species. The difference in PCR-RFLP using Alu  I was also detected in the mitochondrial 16S rRNA gene regions between P. imbricata and the other two species. Thus, the method developed enables the distinction of P. imbricata from P. martensii and P. fucata .     

Energetic physiology of the Caribbean scallops Argopecten nucleus and Nodipecten nodosus fed with different microalgal diets

The Caribbean scallops Argopecten nucleus and Nodipecten nodosus are currently being placed into mass culture in Colombia. The limited availability of wild seed upon which to base these cultures has promoted research into the development of artificial production of this seed in hatcheries. In support of this effort, we studied the effects of different diets on the physiology of the two scallop species in order to determine the optimal feeding regimes for maintenance of adult specimens in the laboratory. Seven monoalgal diets were tested, including Chaetoceros calcitrans, Chaetoceros muelleri, Isochrysis galbana (Ig), Nannochloris oculata (No), Phaeodactylum tricornutum (Pt), Tetraselmis chui (Tc) and Tetraselmis tetrahele (Tt). Four mixed diets were also tested, including I. galbana + C. calcitrans (Ig + Cc), I. galbana + N. oculata (Ig + No), I. galbana + T. tetrahele (Ig + Tt), and I. galbana + lipid emulsion of docosahexanoic acid DHA (Ig + lip). All the dietary trials were carried out under uniform conditions of temperature (25 °C), salinity (36‰) and algal concentration (0.45 mg L^− 1). Physiological variables measured in association with each diet included feeding rates (clearance, ingestion and absorption), oxygen consumption and ammonium excretion rates as well as their scope for growth. The results showed that the best scope for growth for both scallops was obtained with diet Ig since this diet induced the highest feeding rates, accompanied by the lowest oxygen consumption and ammonium excretion. The feeding rates and scope for growth of A. nucleus were greater than those of N. nodosus for the majority of the diets, which was attributed to a higher rate of water pumping by the former species. Greater capacity for branchial food retention by A. nucleus was discarded as a possibility since N. nodosus had a greater branchial surface area per unit dry weight than A. nucleus. In spite of these differences, the oxygen consumption and the excretion rates were similar between the two scallops which suggested that A. nucleus was more efficient in its use of oxygen and retention of body proteins for physiological functioning. Mixed diets or addition of DHA did not permit increases in scope for growth in either of the scallops over that observed using monoalgal diet Ig, which suggest that biologically and economically this diet is optimal for the feeding of adult scallops in the laboratory.     

Insights on endemism: comparison of the duration of the marine larval phase estimated by otolith microstructural analysis of three amphidromous Sicyopterus species (Gobioidei: Sicydiinae) from Vanuatu and New Caledonia

Lord C, Brun C, Hautecœur M, Keith P. Insights on endemism: comparison of the duration of the marine larval phase estimated by otolith microstructural analysis of three amphidromous Sicyopterus species (Gobioidei: Sicydiinae) from Vanuatu and New Caledonia.
Ecology of Freshwater Fish 2010: 19: 26–38. © 2009 John Wiley & Sons A/S
Abstract –  The microstructure of otoliths of three amphidromous gobies (Sicydiinae) of the genus Sicyopterus has been analysed. One of these species, Sicyopterus lagocephalus has a widespread distribution whereas the other two are endemic ( Sicyopterus aiensis , from Vanuatu and Sicyopterus sarasini , from New Caledonia). The microstructural analysis of the otoliths showed that the duration of the marine larval phase is significantly shorter for both endemic species than for the cosmopolitan species (131 ± 3.4 days for S. lagocephalus , 79.2 ± 4.6 days for S. aiensis and 76.5 ± 3.9 days for S. sarasini ). These results led us to infer that it could be one of the factors explaining endemism. We have also improved our knowledge on the processes undergone during the marine phase by studying the growth of the otolith. This work allowed us to propose possible migration routes. These species' reproduction period has also been studied by back-calculating hatching dates. All these elements improve our understanding of the life-history traits and dispersion strategies of these species, which is crucial to implementing conservation measures in order to protect them and their environment, both threatened by anthropogenic actions.     

Relationships between quality parameters and content of glycerol galactoside and porphyra-334 in dried laver nori <Emphasis Type="Italic">Porphyra yezoensis</Emphasis>

ABSTRACT:   Glycerol galactoside (GG; floridoside + isofloridoside) and porphyra-334 (P-334) are contained in nori (Susabinori Porphyra yezoensis and Asakusanori Porphyra tenera ). Glycerol galactoside has been found to have bifidogenic growth stimulator activity and P-334 is known to have ultraviolet-absorbing activity in the UVA region of sunlight. These substances have, respectively, potential for application to pre-biotic foods and in cosmetics as a sunscreen. In the present study, to investigate the relationships between GG and P-334 contents and the quality of nori, we measured the GG and P-334 contents with other components (total protein, chlorophyll-a, β-carotene and phycobillins) that are related to the quality of nori samples produced from different production areas and with different qualities. We found that the GG content was closely negatively correlated with the contents of other components, whereas P-334 was positively correlated with the other components. From these results, it is suggested that low-quality nori is a potential source of GG, and as a source for P-334, scraps of nori produced during nori processing should be suitable.     

Genetic identification of native populations of fluvial white-spotted charr <Emphasis Type="Italic">Salvelinus leucomaenis</Emphasis> in the upper Tone River drainage

ABSTRACT:   Stocking of exogenous, hatchery-reared white-spotted charr Salvelinus leucomaenis has been conducted throughout much of their range in Honshu Island, Japan, to increase angling opportunities. Although the native charr populations are thought to have declined because of hybridization with introduced fish, their distribution and genetic status have been uncertain. Fine population structures of charr in the upper Tone River drainage were examined using mitochondrial DNA and microsatellite analyses so as to clarify the presence of native populations. One common mtDNA haplotype was detected in all populations in the Ohashi River and Watarase River, and four and one tributary populations were monomorphic for such haplotypes, respectively. However, several haplotypes, considered to have originated from stocked hatchery fish, were observed in the stocked and the remaining populations. Judging from the genetic integrity over a fine geographic scale, the former were considered as indicative of native populations and the latter as admixtures with hatchery fish. Comparisons of genetic diversity, deviations from the Hardy–Weinberg equilibrium, principal component analysis, and relatedness estimations based on microsatellite DNA can also provide evidence for distinguishing native populations from those influenced by hatchery fish.     

Breeding and juvenile culture of the lined seahorse, Hippocampus erectus Perry, 1810

All seahorse species worldwide have been placed under CITES Appendix II since 2004, because they have been over-exploited for traditional Chinese medicine and aquarium trades. Aquaculture has been recognized as a long-term solution for sustaining the seahorse trade while minimizing wild collection. In this study, we evaluated the breeding and juvenile culture of an important aquarium seahorse species, the lined seahorse Hippocampus erectus, Perry 1810. Pairing, mating and copulation behavior were observed. Gestation time and brood size were 17.33 ± 2.94 days and 272.33 ± 66.45 individuals/brood, respectively. Growth rates differed among juveniles from different broods. Effects of temperature on the growth rates and survivorship of the juveniles during the first two weeks were compared. The highest growth rate and survivorship of the juveniles occurred at 28–29 °C among the temperatures tested (24–33 °C). Growth rate and survivorship of the juveniles during the first 9 weeks at 28 °C were investigated. The final standard length and survivorship of the juveniles were 6.32 ± 0.52 cm and 71.11 ± 10.18%, respectively, and the relationship between the wet weight and the standard length of the juvenile seahorses can be expressed as: W = 0.0034 L^2.5535 (r² = 0.9903, n = 12, P < 0.01). These findings suggest that H. erectus is a good candidate for commercial aquaculture.     

Larval taxonomy and early identification of topmouth gudgeon Pseudorasbora parva: a screening tool to reduce risks of unintentional species translocation

Abstract  To minimise the risks of unintentional translocation and further spread of the non-native cyprinid, Pseudorasbora parva (Temminck & Schlegel) in the UK, various morphological and meristic characters of this species were measured, with a view to isolating the characters which allow reliable identification of this species during the early stages of development. The combination of myomere numbers, the nature of the internal pigmentation associated with the notochord and the lack of a single row of external melanophores along the route of the lateral line organ reliably facilitate the ability to distinguish this species from the native fauna of the British Isles. Thus, for the first time, fishery managers and environmental agencies have a much needed tool to screen for the presence young-of-the-year of this species when authorising movements of other fish species.