Disinfection of striped trumpeter (Latris lineata) eggs with glutaraldehyde

This study assessed the effect of immersing striped trumpeter eggs in 0 (control), 200, 400, 800, 1600 or 3200 ppm glutaraldehyde for 10 minutes, two days before hatching. High concentrations of glutaraldehyde (1600 and 3200 ppm) resulted in no eggs hatching and only 1% of eggs hatched after treatment with 800 ppm glutaraldehyde. Hatching success of eggs treated with 0, 200 or 400 ppm glutaraldehyde did not differ (77 ± 6%, n = 3). However, only 2% of larvae from the control treatment survived to day 5 post-hatching, compared to 45 and 69%, respectively of the larvae from the 200 and 400 ppm glutaraldehyde treatment. By day 9 post-hatching, larvae from the 400 ppm glutaraldehyde treatment had significantly higher survival (59%) than larvae from the 200 ppm glutaraldehyde treatment (28%). Thiosulphate citrate bile salt sucrose agar (TCBS) medium confirmed the presence of bacteria within the seawater medium, on all control eggs and on 83% of eggs disinfected with 200 ppm glutaraldehyde, but no bacterial colonies formed on eggs treated with 400, 800, 1600 or 3200 ppm glutaraldehyde. This study found highest survival of striped trumpeter larvae from eggs disinfected with 400 ppm glutaraldehyde and suggests that increased survival was a result of reduced bacterial loading.     

Tolerance of striped trumpeter Latris lineata embryos to ozonated seawater

The tolerance of striped trumpeter, Latris lineata (Bloch and Schneider 1801) embryos to ozonated seawater was examined as a possible means of disinfection. The effect of a range of ozone doses and exposures (CT = concentration × exposure time) was tested at different stages of embryonic development. Three-day-old embryos two-thirds developed around the yolk were exposed for 0.5, 1 or 5 min to ozone concentrations of 0.5, 1, 2 and 5 mg O₃ l⁻¹ in a fully orthogonal factorial design. For each treatment there were four replicate 250 ml containers that each received 100 ± 15 embryos. There was no significant difference in hatching success between control-treated embryos or embryos ozonated at 0.5 or 1 mg O₃ l⁻¹ for 0.5, 1 or 5 min (P < 0.05). However, hatching success was significantly reduced when embryos were treated with 2 or 5 mg O₃ l⁻¹ for 5 min or 5 mg l⁻¹ O₃ for 1 min (P < 0.05). The tolerance of embryos to 0, 0.5 or 2 mg O₃ l⁻¹ for 1 min at different stages of development (Day 0, 1, 2, 3 or 4), was then examined. An ozone concentration of 0.5 mg l⁻¹ had no effect on hatching success at any stage of development, but a concentration of 2 mg l⁻¹ significantly reduced hatching success on all days except Day 3. A safe and tested hatchery practise is to disinfect striped trumpeter embryos with 1 mg O₃ l⁻¹ for 1 min on Day 3 post-fertilisation when the embryo is two-thirds developed around the yolk.     

Sensitivity of striped trumpeter, Latris lineata, embryos to mechanical shock and simulated transport

The sensitivity of striped trumpeter, Latris lineata, embryos to transport was assessed through mechanical shock at four stages of embryonic development, and simulated transport at different densities and durations. Fertilised egg mortality due to mechanical shock was greatest for embryos shocked 3 and 27 h post-fertilisation (48.6% ± 4.1 and 36.0% ± 3.2, respectively; mean ± SE), and prior to blastopore closure. Mortality of embryos shocked 51 and 75 h post-fertilisation, and following blastopore closure, did not differ from un-shocked controls (9.5% ± 0.7). Density and duration of incubation affected the survival of embryos in a simulated transport trial. Embryonic mortality remained below 3% for all density treatments up to 24 h post-fertilisation. Significant mortality of fertilised eggs occurred when incubated at 5,000 embryos l⁻¹ (17.2% ± 6.9) for 48 h and was correlated with a drop in dissolved oxygen (DO) levels. Final DO concentrations decreased with increasing embryonic density and incubation duration. DO of embryos incubated at 5,000 embryos l⁻¹ was significantly lower than those incubated at 500, 1,000 and 2,500 embryos l⁻¹, at all incubation durations. Mortality was prevalent in treatments that had a final DO level less than 72% saturation at 14°C. Transportation of fertilised striped trumpeter eggs in seawater is recommended from 51 h post-fertilisation at 14°C, after blastopore closure and neural keel development and at densities of no more than 2,500 embryos l⁻¹ for 24 h transportation duration.     

Host response to the chondracanthid copepod Chondracanthus goldsmidi,a gill parasite of the striped trumpeter,Latris lineata (Forster), in Tasmania

The chondracanthid copepod, Chondracanthus goldsmidi is an ectoparasite of gills, inner opercula and nasal cavities of cultured striped trumpeter, Latris lineata (Forster). Whilst often present in high numbers (up to 60 parasites per host), little is known about its effect on striped trumpeter. In this study C. goldsmidi was associated with extensive epithelial hyperplasia and necrosis. Pathological changes were most pronounced near the parasite’s attachment site, with papilloma‐like growths surrounding the entire parasite resulting in deformation of the filament. The number of mucous cells increased near the parasite attachment sites on both the opercula and gills. Mast cells were absent in healthy gills; in contrast numerous mast cells were identified in the papilloma‐like growths. Immunostaining identified piscidin‐positive mast cells in the papilloma‐like growths, presenting the first evidence of piscidin in the family Latridae.     

Combined effects of feeding enriched rotifers and antibiotic addition on performance of striped trumpeter (Latris lineata) larvae

Striped trumpeter have a complex and extended larval phase and are difficult to culture. Two experiments were conducted in replicated, 300-l hemispherical tanks to determine if larval survival, growth, bacterial or fatty acid profile were improved by feeding non-enriched rotifers or rotifers enriched with algae or commercially available products, as well as the effect of an antibiotic, oxytetracycline (OTC). Larvae were stocked at 25 l^− 1 and 15 l^− 1 and reared until Day 16 and Day 19 in Experiments 1 and 2, respectively. In Experiment 1, the feeding treatments were non-enriched rotifers, or rotifers enriched on algae, DHA Selco (a fish oil based emulsion) or RotiMac (dried Schizochytrium). There were no significant differences in mean survival (± SD) across treatments, which were generally low at 14.6 ± 5.2%. Larvae reared on rotifers fed DHA Selco and RotiMac, had significantly higher proportions of incorporated DHA but no significant increase in growth. In Experiment 2, larvae were fed rotifers enriched on DHA Selco or AlgaMac 2000 and reared with or without the daily addition of 25 mg l^− 1 OTC. At Day 19, there was significantly higher survival for larvae reared on AlgaMac 2000 and OTC, (37.4 ± 5.6%), than DHA Selco and OTC, (16.0 ± 7.4%), AlgaMac 2000 without OTC (7.0 ± 8.0) and DHA Selco without OTC (3.3 ± 1.2). Larvae reared with OTC were larger (279 ± 58 μg and 7.4 ± 0.2 mm) than without OTC (177 ± 40 μg and 6.3 ± 0.2 mm). The addition of antibiotics did not significantly influence fatty acid profiles of larvae. There were no significant differences in the percentage of DHA, 27.6 ± 2.8%, EPA 4.6 ± 1.0% or ARA 4.9 ± 0.4%. Larvae reared with OTC had significantly less ‘grey gut’ (a measure of intestinal dysfunction). The results indicated that bacterial infection was a major source of mortality in striped trumpeter larvae and compromised larval growth. Assessment of the bacterial flora indicated that antibiotic use reduced the bacterial load, but did not eliminate potential pathogens. Our study suggests that microbial control has a greater influence than lipid nutrition on the survival and growth of larvae during the rotifer feeding stage.     

Pentacapsula neurophila sp.n. (Multivalvulida) from the central nervous system of striped trumpeter,Latris lineata (Forster)

Striped trumpeter, Latris lineata, are being experimentally cultured by the Tasmanian Aquaculture and Fisheries Institute at Taroona, Tasmania. Fish surviving over 30 days post-hatching have frequently developed nervous aberrations associated with a severe granulomatous meningoencephalomyelitis. The myxozoan parasite Pentacapsula neurophila sp.n. was revealed as the parasite causing the disease in the striped trumpeter juveniles. Measurements made of isolated spores indicated that the organism was distinct from all previously described Pentacapsula species. This is the first report of a marine myxozoan parasite of the genus Pentacapsula in Australian waters.     

Effect of dietary 22:6n-3 on growth,survival and tissue fatty acid profile of striped trumpeter (Latris lineata) larvae fed enriched Artemia

The effect of dietary 22:6n-3 (docosahexaenoic acid, DHA) on growth and survival was determined in striped trumpeter during metamorphosis and the Artemia-feeding period (16–36 days posthatch, dph). Artemia were enriched on one of five experimental emulsions that contained graduated concentrations of DHA and constant 20:4n-6 (arachidonic acid, ARA). We also compared larval performance using a commercial enrichment product high in n-3 PUFA. Final DHA concentrations in Artemia enriched on the experimental emulsions ranged from 0.1–20.8 mg/g DM, while Artemia fed the commercial product had 18.2 mg DHA/g DM. Each of the six diets was fed to larvae in four replicate 300-l tanks. Standard length (range 10.0–11.2 mm) and dry weight (range 1.6–2.5 mg) of larvae at the end of the experiment were directly related to dietary DHA, with the highest growth recorded in the experimental diet with the greatest concentration of DHA (20.8 mg/g DM). Survival at 36 dph was not influenced by dietary DHA and ranged from 20–44%. Mortality increased noticeably, regardless of dietary treatment, when larvae attained a standard length of approximately 9.5 mm. Mortality was related to a nocturnal behaviour where larvae would migrate to the tank bottom during the dark phase. Fatty acid profiles of the larvae were generally correlated to dietary fatty acids. Dietary DHA was found to be important in larval striped trumpeter growth, where enhanced growth probably shortened the critical period of metamorphosis and the window where nocturnal downward migration and mortality occurred.     

Ultraviolet irradiation is an effective alternative to ozonation as a sea water treatment to prevent Kudoa neurophila (Myxozoa: Myxosporea) infection of striped trumpeter,Latris lineata (Forster)

Myxozoan parasites are known pathogens of cultured finfish. Kudoa neurophila n. comb. (Grossel, Dyková, Handlinger & Munday) has historically infected hatchery‐produced striped trumpeter, Latris lineata (Forster in Bloch and Schneider), a candidate species for seacage aquaculture in Australia. We examined the efficacy of four water treatment methods to prevent K. neurophila infection in post‐larval (paperfish) and juvenile striped trumpeter. Treatments included dose‐controlled ultraviolet irradiation [hydro‐optic disinfection (HOD)], ozone with conventional UV (ozone), mechanical filtration at 25 μm and then foam fractionation (primary filtration), and 50‐μm‐filtered sea water (control). In post‐larvae (initially 10.3 ± 2.7 g, mean ± SD, 259 days post‐hatching, dph), the infection prevalence (PCR test) after 51 days was 93 ± 12% in the control, 100 ± 0% in primary filtration and 0 ± 0% in both ozone and HOD. Likewise, in juveniles (initially 114 ± 18 g, 428 dph), prevalence was 100 ± 0% in the control and primary filtration treatments with no infection detected in ozone and HOD. Concurrently, there was a 50–100% reduction in heterotrophic bacteria and 100% reduction in presumptive Vibrio sp. in sea water HOD and ozone treatments. HOD with a dose of ≥44 mJ cm^?2 UV was as effective as ozonation at >700 mV ORP for 10 min, in preventing K. neurophila infection.     

Status of galaxiid fishes in Tasmania,Australia: conservation listings,threats and management issues

• 1. Fish of the family Galaxiidae are restricted to the southern hemisphere where they occupy a diverse array of habitats ranging from over 2000 m in elevation to sea level. Some species are diadromous and, hence, freshwater, estuarine and marine habitats are used during their life‐cycle; other species complete their entire life‐cycles in freshwater environments.
• 2. Tasmania has a diverse galaxiid fauna that accounts for 64% of native freshwater fish species found on the island. The Tasmanian galaxiid fauna is characterized by high species richness (5 genera and 16 species), endemism (11 species), restricted distributions, and non‐diadromous life histories (11 species).
• 3. The galaxiid fauna of Tasmania has significant conservation status with 69% of species considered ‘threatened’. The conservation status of the fauna is recognized at State, national and international levels.
• 4. The key threats to galaxiids in Tasmania are exotic species, hydrological manipulations, restricted distributions, general habitat degradation and exploitation of stocks.
• 5. Although work has recently been undertaken to conserve and manage Tasmanian galaxiid populations, the fauna is still thought to be imperilled. Knowledge gaps that need to be addressed include the biology and ecology of most species (e.g. reproductive biology, life histories, habitat use and requirements) and impacts of habitat manipulations, as well as mechanisms and impacts of interactions with exotic species. Techniques to monitor accurately the status of galaxiid species and their populations need to be developed and the coexistence of some galaxiids with introduced salmonids should also be examined.

Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of temperature on hatching success and size of striped trumpeter (Latris lineata) larvae

Egg samples were collected from captive striped trumpeter maintained under phase-shifted and simulated ambient photothermal regimes and incubated at 9, 10, 11, 12, 13, 14, 15 or 16 °C. No eggs hatched at 9 °C. Time to hatch decreased from 9.6 to 4.2 days as temperature increased from 10 to 16 °C. Survival to hatch was low at 10 and 11 °C, but similar within the range 12–16 °C. Larval length at hatching was greatest at 14 °C, with no significant difference in yolk volume or muscle depth at vent across the range of temperatures. The results of our study suggest that the optimal temperature for the incubation of striped trumpeter eggs is 14 °C, which is higher than found previously.     

Reproductive biology of pink dentex Dentex gibbosus (Rafinesque) from the Adriatic Sea, Croatia

A 4‐year study (May 1997–December 2000) of the reproductive biology of pink dentex Dentex gibbosus (Rafinesque) from the Adriatic Sea revealed that this species is a rudimentary hermaphrodite. The smallest mature males and females captured were 38.70 cm in total length (T_L) and 39.80 cm in total length (T_L) respectively. The von Bertalanffy growth parameters estimated for the entire population were: L_∞=107.24, K=0.12 and t₀=−0.90. Fifty per cent of the population were sexually mature at 41.50 cm T_L, while 100% of the specimens were sexually mature at 57.00 cm T_L. Both monthly gonadosomatic index and macroscopically determined gonad stages strongly indicate that the pink dentex from the Adriatic Sea spawn partially in August, September and October. The mean value of absolute fecundity (F) was 1672 × 10⁶ eggs. The results of great fertility of the pink dentex, partial spawning and relatively late sexual maturation suggest that the pink dentex has a high potential for commercial culture.     

Reproductive biology of Venus clam Gafrarium tumidum (Roding, 1798) from Southeast coast of India

The reproductive biology of tumid venus clam Gafrarium tumidum (Roding) was studied in detail from the Southeast coast of India. Sample size ranged from 10.3 to 41.3 mm. Sexes are separate but not differentiated externally. Annual sex ratio male:female (M:F) deviated significantly from the 1:1 ratio with females dominating. Based on ova diameter progression of gonad smear and histology, four and two maturity stages of gonads were differentiated in female and male clams, respectively. Peak spawning was observed during November and a minor one in April. The monthly average condition index based on wet/dry flesh weight ranged from 7.24 (November) and 14.14 (September) and 8.82 (October) and 14.38 (August), respectively. The condition index observed by both the methods is comparable and corresponds with the spawning season. Water content observed for male and female clams varied negligibly and showed positive correlation with spawning period. Size at first maturity was estimated to be 22.3 mm.     

Dietary Arachidonic Acid Alters Tissue Fatty Acid Profile, Whole Body Eicosanoid Production and Resistance to Hypersaline Challenge in Larvae of the Temperate Marine Fish, Striped Trumpeter (Latris lineata)

We determined the effect of dietary arachidonic acid (20:4n-6, ARA) on tissue ratios of ARA/eicosapentaenoic acid (20:5n-3, EPA) and subsequent whole body production of the eicosanoids, prostaglandin F_2α (PGF_2α) and E₂ (PGE₂) in the marine larvae of striped trumpeter, Latris lineata. Larvae were also subjected to a hypersaline challenge (55 ppt) with an aim to determine possible relationships between tissue fatty acid profiles, prostanoid production, and their tolerance to osmotic challenge. From 5 to 23 days post-hatch (dph) larvae were fed live food, rotifers (Brachionus plicatilis), that had been enriched with one of five experimental emulsions containing increasing concentrations of ARA and constant EPA and 22:6n-3 (docosahexaenoic acid, DHA). Final ARA concentrations in the rotifers were 1.33, 3.57, 6.21, 8.21 and 11.22 mg g⁻¹ DM. Larval growth and survival was unaffected by dietary ARA. Tissue fatty acid concentrations generally corresponded with dietary fatty acids and final tissue ratios of ARA/EPA ranged from 0.9 to 4.9. At 18 and 23 dph whole body concentrations of PGF_2α and PGE₂ generally increased as more dietary ARA was provided in a dose-response manner, and a significant elevation in both PGF_2α and PGE₂ in larvae fed the highest dietary ARA concentration was recorded at 23 dph compared to larvae receiving the lowest concentration. At 18 dph, the highest cumulative inactivity following a hypersaline challenge occurred in larvae fed 8.21 or 11.22 mg ARA g⁻¹ DM, which was significantly greater than those receiving 3.57 mg ARA g⁻¹ DM. At 23 dph no relationship between inactivity of larvae subjected to a hypersaline challenge to dietary ARA was evident. In summary, dietary ARA altered tissue ARA/EPA ratios, prostanoid production and resistance to a hypersaline challenge in larval striped trumpeter. While increasing dietary ARA generally resulted in elevation of prostanoids as well as increasing the number of inactive larvae following a hypersaline challenge at 18 dph, similar trends between prostanoids and larval inactivity were not evident at 23 dph, suggesting the exact mechanisms and relationships between eicosanoids and larval osmoregulation warrants further investigation. Nevertheless the study provides preliminary data on the effect of dietary ARA on the prostaglandin production in marine fish larvae.     

Reproductive biology of white mullet,Mugil curema (Valenciennes) in the Southern Caribbean

Gonadal development and spawning of white mullet, Mugil curema in the Gulf of Paria, Trinidad, West Indies, was investigated using both macroscopic and histological techniques. M. curema is a multiple batch spawner with a protracted spawning season from November to July. Gonadal development is annual and each female appears to spawn at least twice per year. The prolonged spawning season may thus be an indication of the lack of population synchrony rather than prolonged spawning by a single individual. Peak-spawning activity occurs in June/July and it is hypothesized that it is in response to the start of the rainy season. Oocyte development is group synchronous and development of oocytes in the leading clutch is isochronal.     

Fertilization efficiency of cryopreserved sperm from striped catfish, Pangasius hypophthalmus (Sauvage)

The fertilization efficiency of cryopreserved sperm was compared with fresh sperm from striped catfish, Pangasius hypophthalmus . Of the two sets of experiments carried out, the first compared four sperm doses using fresh sperm and fresh eggs. The second experiment compared six concentrations of cryopreserved sperm ranging from 6.94 × 10⁷ to 6.94 × 10¹⁰ to fertilize 100 eggs per batch. Fertilization, hatch and survival rates were compared between cryopreserved and fresh sperm. The highest fertilization rate (53.75±1.62%) was achieved with a sperm dose of 6.94 × 10⁸. Increasing the sperm dose to 3.47 × 10⁹ did not increase the fertilization rate, indicating that the optimum sperm:egg ratio lies between 6.94 × 10⁶ and 3.47 × 10⁷ sperm per egg. Both highest (6.94 × 10¹⁰) and the lowest (6.94 × 10⁷) sperm doses resulted in lower fertilization rates (2.04% and 16.90% respectively). No significant differences were found among four fresh sperm doses compared. Mean hatch and survival rates resulting from fresh and cryopreserved sperm were similar. The experiment shows that while only 1.89 × 10⁶ fresh spermatozoa was required to fertilize a fresh egg, 6.94 × 10⁶ (or 3.67 times more) cryopreserved sperm was required to achieve the same level of fertilization. This provides important information for making decision to cryopreserve sperm for commercial and/or conservation purposes.     

Reproductive biology of a hillstream catfish, Glyptothorax madraspatanum (Day), from the Garhwal, Central Himalaya, India

Abstract. This paper studies maturity and spawning tendency of a hillstream catfish, Glyptothorax madraspatanum (Day), in the Western Nayar River, Garhwal, Central Himalaya, India. The fish is a protracted spawner as it spawns only once during the limited period from July to August. Fecundity ranges from 1640 to 6830 eggs and is more closely related to ovary weight and fish weight than ovary and fish length. There was a non-significant sex ratio of 1:1·24 between males and females.     

Reproductive biology of the carp, Labeo bata (Ham.) from the River Kali,India

Spawning in Labeo bata occurs during July and August. Each individual spawns only once, with the onset of spawning directly dependent on the monsson season. Its success depends upon the access of gravid fish to a suitable spawning ground. The average fecundity is 192 785.     

Reproductive biology of ridgeback shrimp Solenocera choprai (Decapoda, Penaeoidea, Solenoceridae) off Mangalore coast, south India

Abstract:   The ridgeback shrimp Solenocera choprai has emerged as one of the important commercial species in 60–100 m depth zone off Karnataka coast, India, since 1993. Studies were conducted on S. choprai to understand its reproductive biology which can help in formulating policies for management of the species. The diagnostic features of reproductive morphology of the species were studied and illustrated in detail. Based on the coloration and size of the ovary and ova diameter variations, five stages of maturity in female S. choprai were identified. The mature ova are fully yolked with diameters between 0.24 and 0.35 mm. Size at maturity (50%) has been estimated at 54.5 and 66.5 mm total length (TL) in males and females, respectively. The gonadosomatic index (GSI) showed an increasing trend according to the advancement of maturity of the ovary, and monthly mean GSI showed a positive correlation with monthly percentage of spawners. Solenocera choprai was found to be a continuous breeder with two peaks: a major peak in November and another extended peak during January–February. The estimated numbers of ova in the mature ovary were 38 532 and 133 689 in shrimps measuring 80 and 110 mm TL, respectively. A sigmoidal increase in the female-to-male sex ratio with increase in size was noticed in the species. A χ ²-test showed that the annual distribution of females and males is not significantly different from a 1:1 ratio at the 1% level.     

Purification,characterization and immunoassay of striped bass (Morone saxatilis) vitellogenin

The egg yolk precursor, vitellogenin (VTG), was purified from blood plasma of striped bass by chromatography on hydroxylapatite or DEAE-agarose. The fish were first implanted with estradiol-17β (E₂), which induced vitellogenesis. A rabbit antiserum (a-FSPP) raised against plasma from mature female striped bass, and then adsorbed with mature male plasma, was used to detect female-specific plasma protein (FSPP) in the chromatography fractions. Striped bass VTG (s-VTG) was collected from the peak fraction that was induced by E₂, reacted with a-FSPP, and contained all detectable phosphoprotein. It appeared as a single band (M_r ≂ 170,000) in SDS-PAGE or Western blots using a-FSPP, and as a pair of closely-spaced phospholipoprotein bands in native gradient-PAGE, suggesting that there is more than one circulating form of s-VTG. The relationship of s-VTG to the yolk proteins was verified using a-FSPP. The antiserum reacted with the main peak from gel filtration of saline ovary extracts, and it specifically immunostained the two main bands in Western blots of the extracts and the yolk granules of mature oocytes. The amino acid composition of s-VTG was similar to that of VTG from other fish and Xenopus. A radial immunodiffusion assay for s-VTG was developed using a-FSPP and purified s-VTG as standard. The s-VTG was not detected in blood plasma of males, immature females, or regressed adult females, but plasma s-VTG levels were highly correlated with plasma E₂ and testosterone levels, and oocyte growth, in maturing females. The results indicate that the maturational status of female striped bass can be identified by s-VTG immunoassay.