Larviculture newsletter < Year 2005 < Issue 215

ELECTRONICAL LARVICULTURE NEWSLETTER ISSUE 215
March 1, 2005

1. AQUACULTURE EUROPE 2005. LESSONS FROM THE PAST TO OPTIMIZE THE FUTURE NORWAY, AUGUST 5-9, 2005.
2. CROSS-BREEDING STUDIES IN SEVEN ARTEMIA FRANCISCANA STRAINS FROM MEXICO
3. CHARACTERIZATION OF A NEW PARTHENOGENETIC ARTEMIA POPULATION FROM THAMARAIKULAM, INDIA
4. THE EFFECT OF TANK COLOURATION ON SURVIVAL, METAMORPHOSIS RATE, GROWTH AND TIME TO METAMORPHOSIS FRESHWATER PRAWN (MACROBRACHIUM ROSENBERGII) REARING
5. INCIDENCE OF WHITE MUSCLE DISEASE, A VIRAL LIKE DISEASE ASSOCIATED WITH MORTALITIES IN HATCHERY-REARED POSTLARVAE OF THE GIANT FRESHWATER PRAWN MACROBRACHIUM ROSENBERGII (DE MAN) FROM THE SOUTH-EAST COAST OF INDIA
6. SHORT COMMUNICATION: REARING OF SQUID HATCHLINGS, HETEROLOLIGO BLEEKERI (KEFERSTEIN 1866) UP TO 2 MONTHS IN A CLOSED SEAWATER SYSTEM
7. DIETARY VITAMIN A REQUIREMENTS OF JUVENILE JAPANESE FLOUNDER PARALICHTHYS OLIVACEUS L.H.H.
8. EFFECTS OF VARYING DIETARY PROTEIN LEVELS ON GROWTH, REPRODUCTIVE PERFORMANCE, BODY AND EGG COMPOSITION OF ROHU, LABEO ROHITA (HAMILTON)
9. EFFECT OF MICROALGAL BIOMASS CONCENTRATION AND TEMPERATURE ON ORNAMENTAL GOLDFISH (CARASSIUS AURATUS) SKIN PIGMENTATION
10. MATERNAL AND SEASONAL DIFFERENCES IN EGG SIZES AND SPAWNING ACTIVITY OF NORTHWEST ATLANTIC HADDOCK (MELANOGRAMMUS AEGLEFINUS) IN RELATION TO BODY SIZE AND CONDITION
11. PREDATOR-RECOGNITION TRAINING OF HATCHERY-REARED WALLEYE (STIZOSTEDION VITREUM) AND A FIELD TEST OF A TRAINING METHOD USING YELLOW PERCH (PERCA FLAVESCENS)
12. LONG-RESIDENCE GROUNDWATER EFFECTS ON INCUBATING SALMONID EGGS: LOW HYPORHEIC OXYGEN IMPAIRS EMBRYO DEVELOPMENT
13. ANNUAL CHANGES IN OVARIAN DEVELOPMENT AND PLASMA ESTRADIOL-17 LEVEL IN REARED FEMALE COMMON JAPANESE CONGER, CONGER MYRIASTER
14. THYROID HORMONE DEFICIENCY IN ABNORMAL LARVAE OF THE JAPANESE FLOUNDER PARALICHTHYS OLIVACEUS
15. OPTIMUM DIETARY PHOSPHORUS LEVEL OF JUVENILE JAPANESE FLOUNDER PARALICHTHYS OLIVACEUS REARED IN THE RECIRCULATING SYSTEM
16. ZOOPLANKTON DISTRIBUTION IN FOUR PONDS OF DIFFERENT SALINITY: A SEASONAL STUDY IN THE SOLAR SALTERNS OF SFAX (TUNISIA)
17. FREE FATTY ACIDS AND STEROLS IN THE BENTHIC SPAWN OF AQUATIC MOLLUSCS, AND THEIR ASSOCIATED ANTIMICROBIAL PROPERTIES
18. PRELIMINARY OBSERVATIONS OF TOPICAL GILL APPLICATION OF REPRODUCTIVE HORMONES FOR INDUCED SPAWNING OF A TROPICAL ORNAMENTAL FISH
19. GROWTH OF POSTLARVAL MACROBRACHIUM ROSENBERGII AT TWO TEMPERATURES
20. A SIMPLE ISOLATION INCUBATOR FOR SPECIALIZED REARING OF SALMONID EGGS AND FIRST-FEEDING FRY
21. A SIMPLE ASSAY TO COMPARE ZEOLITE AMMONIA CONTROL PROPERTIES
22. BACTERIAL NUMBERS FROM LANDLOCKED FALL CHINOOK SALMON EYED EGGS SUBJECTED TO VARIOUS FORMALIN TREATMENTS AS DETERMINED BY SCANNING ELECTRON MICROSCOPY AND BACTERIOLOGICAL CULTURE METHODS
23. AN EXTENDER SOLUTION FOR THE SHORT-TERM STORAGE OF STURGEON SEMEN
24. MORTALITY OF FISH LARVAE EXPOSED TO VARYING CONCENTRATIONS OF CYCLOPOID COPEPODS

AQUACULTURE EUROPE 2005. LESSONS FROM THE PAST TO OPTIMIZE THE FUTURE NORWAY, AUGUST 5-9, 2005.

From August 5-9, 2005, Trondheim (Norway) will be the meeting place for the Aquaculture Europe 2005 conference on " Lessons from the past to optimize the future ". Immediately following the conference, the Aqua Nor trade show, the largest aquaculture trade exhibition of its kind, will open its doors from August 9-12. Conference delegates have free access to this event.

This event is organised by the European Aquaculture Society (EAS) in joint cooperation with The Nor-Fishing Foundation It furthermore enjoys the moral support of some major Aquaculture Societies in Europe.

The conference is to address the sustainability of aquaculture: “Lessons from the past to optimise the future”

Recent decades have seen major developments throughout the world in the farming of aquatic organisms for food. In Europe, trout, and other freshwater fish farming has continued to develop, although developments in sea fish farming have predominated with cage culture of salmon, sea bass and sea bream hugely increasing the availability of these species in the market place. Although a range of alternative approaches (e.g. extensive culture in enclosed bays, and ranching/stock enhancement in fjords and the open sea) were considered, for various biological, political and commercial reasons significant developments have been limited to intensive culture in cages and tanks.

Preliminary conference programme
Plenary sessions will be held during the first part of the morning and will address the following key themes:
Applying lessons learned from established species.
The capacity of the environment to support predicted growth.
The contribution of aquaculture to sustainable fisheries.
Developments in environmentally friendly systems.
Ethics: issues and their communication.

Parallel sessions will be held late morning and afternoon. They will include themes #2-5 above. Contributions on all cultured species are welcomed for each topic.

The capacity of the environment to support predicted growth
Including research on measuring carrying (productive, assimilative) capacity; manipulating carrying capacity (upwelling, reefs); multiple use and ICZM issues; Aquaculture as a tool in environmental protection: biodiversity issues and scientific basis for legislation.

The contribution of aquaculture to sustainable fisheries
Including research on stocking strategies in freshwater and marine environments; implications for rearing methodology (behavioural, genetic, disease issues); cost benefit and ownership issues

Developments in environmentally-friendly systems
Including offshore, recirculation and integrated systems; effluent systems; farm design; bio-fouling prevention and escape prevention

Ethics: issues and their communication
Including scientific basis for good welfare practice / legislation; slaughter methods; manipulated strains and communication initiatives/strategies

Health management
Including disease prevention (vaccination strategies, immuno-stimulants, selection); stress control; bio-security and containment (etiology, vectors & latent carriers, transport/movement).

Sustainable feed resources
Including alternatives to fish meal/oil: effects on performance, quality and consumer perceptions; projected availability of high quality fish meal and oil; cost benefit analysis of alternatives.

Reliability of hatchery production
Including quality criteria / viability indicators for all facets / life stages; broodstock management and gamete quality; water management (including microbes) and feed quality (live and formulated).

Towards economic sustainability
Including market dynamics, emerging new species; product quality and safety; governance & self-regulation and socio-economic aspects.
Other events during AE2005

EU Forum on the 6th & 7th Framework Programmes of RTD
Representatives of the European Commission Directorate General
Fisheries will present the latest news on the 6th Framework programme
(2002 – 2006) and an update on the development of the 7th Framework Programme of research and technological development (2007-2011), especially concerning aquaculture and fisheries. Following the presentation, the floor will be open for discussion.

A special Aquaculture Innovation Network event
On the first day of the Aqua Nor exhibition (August 9), EAS, through its participation in the CNS-INTRANS EU funded network (www.aquainnovation.net), is organising a special event in the frame of the goals of this network, including assistance of companies in developing worthwhile collaborations, accessing information about innovation and supporting and guiding technology transfer.

The trade exhibition (Aqua Nor)
The Aqua Nor 2005 trade show will take place from August 9-12, immediately following the conference. Aqua Nor has been organised since 1979 and is the leading exhibition of its kind, comprising indoor and outdoor displays of the latest products, services, research and developments in aquaculture. Organised bi-annually, it is the primary meeting place for fish farmers, suppliers and others involved in the fresh and processed seafood selling chain linked with aquaculture. Aqua Nor 2003 attracted 20.000 visitors from 50 countries and 492 companies were represented.

More information
First announcement, call for contributions, registration forms and other practical information http://www.easonline.org/agenda/en/AquaEuro2005/default.asp

The conference secretariat can be contacted by email at :ae2005@aquaculture.cc and by fax at +32 59 32 10 05
CSN-INTRANS www.aquainnovation.net
Aqua Nor 2005 http://www.nor-fishing.no/

CROSS-BREEDING STUDIES IN SEVEN ARTEMIA FRANCISCANA STRAINS FROM MEXICO Jorge Castro Mejía, Thalía Castro Barrera, José Luis Arredondo Figueroa, Germán Castro Mejía, Andrade Ramón de Larai, Aída Malpica Sánchez-2004
Journal of Biological Research, 2: 35-41
Abstract:
Cross-breeding experiments were performed on seven Mexican strains of Artemia franciscana to determine their status of reproductive isolation. The populations used in this study were: Yavaros (YAV), Ohuira (OHUI), Juchitan (JUCH), Real de las Salinas (R.SAL), Cuatro Cienegas (C.CIEN), Las Salinas de Hidalgo, San Luis Potosi (SLP) and Texcoco (TEX). Each population was cultured in a 40-1 tank. Feeding consisted of a mixture of Tetraselmis sp. and Dunaliella sp. When the organisms had reached the pre-adult stage, males and females were separated. For cross-breeding experiments, one female from one population and two males from another population were placed in a 250-ml flask; the same procedure was followed for the reciprocal crosses. Once the presence of nauplii (Ft) was observed, they were placed in another flask until they were sexually mature. From the 42 cross-breeding tests performed, only seven presented 100% reproductive success, while 15 were not successful. For F2, the number of successful cross-breedings dropped drastically, showing increased sterility. Only the crossbreeding involving female TEX/males R.SAL maintained high nauplii production in Ft and F2 (445 and 401, respectively). We can conclude that the studied Mexican populations of Artemia franciscana are in the process of building post-zygotic reproductive isolation (hybrid breakdown), caused by the ecological preferences and/or adaptation of each population to its specific habitat. This might be reflected in their genotype, inducing pre- and post-mating alterations
(Universidad Autonoma Metropolitana-Xochimilco, Depto. El Hombre y su Ambiente, Laboratorio Produccion de Alimento Vivo, Calz. del Hueso No. 1100, Colonia Villa Quietud, Mexico, 04960, D.F.; email of J. Castro Mejía: camj7509@cueyatl.uam.mx)

CHARACTERIZATION OF A NEW PARTHENOGENETIC ARTEMIA POPULATION FROM THAMARAIKULAM, INDIA
Cristopher J.A. John, Theodore J. Abatzopoulos, Peter M. Marian-2004
Journal of Biological Research, 2: 63-74
Abstract:
The brine shrimp Artemia (Crustacea, Anostraca) is a well-known organism used as live feed for finfish and shellfish larvae. Here we report on a new population of Artemia, identified in saltpans of Thamaraikulam, India. The characterization of this strain involved cyst, naupliar and adult biometrics, as well as carbohydrate, protein, lipid, ash and energy content estimations. The fatty acid profile of the cysts was also analysed. The cyst diameter, nauplius and adult length of this Artemia strain were 244.9 mm, 492.8 mm and 10.60 mm, respectively. Moreover, the optimal temperature and salinity conditions resulting in maximum survival were 22-30°C and 35 ppt, respectively. It is worth noting that this population can survive in a wide range of temperatures, but in a very narrow range of salinity. These data suggest that this new Artemia population is different from other studied parthenogenetic strains in terms of its biometrical characteristics and temperature and salinity tolerance.
(Institute for Artemia Research and Training, Center for Marine Science and Technology,
M.S. University Marina Campus, Rajakkmangalam - 629502, Kanyakumari District, Tamil Nadu, India)

THE EFFECT OF TANK COLOURATION ON SURVIVAL, METAMORPHOSIS RATE, GROWTH AND TIME TO METAMORPHOSIS FRESHWATER PRAWN (MACROBRACHIUM ROSENBERGII) REARING
David Yasharian, Shawn D. Coyle, James H. Tidwell, William Earl Stilwell-2005
Aquaculture Research, 36 (3): 278-
Abstract:
Seedstock-costs of the freshwater prawn Macrobrachium rosenbergii can represent >50% of the total production costs. The purpose of this study was to evaluate the effect of culture tank colouration on survival, metamorphosis rate, weight and time required to reach the postlarval (PL) stage. Newly hatched prawn larvae were stocked into eighteen 16-L plastic culture tanks at a density of 30 L 1. Tank colours evaluated were red, black, white, blue, green and yellow. Larval prawns were fed brine shrimp (Artemia franciscana) nauplii and a supplemental diet. Data indicated that larval tank colour had no significant impact (P>0.05) on the final PL size or days required to reach PL stage. However, total survival was significantly higher (P<0.05) in red and green tanks (84% and 78% respectively) than in white and blue tanks (56% and 44% respectively). Survival in the yellow and black tanks (71% in both) was not significantly different (P>0.05) from the red, green or white treatments, but was significantly higher (P<0.05) than the blue treatment. This could have a significant financial impact on commercial hatchery, and growout production, as most larval tanks currently in use are blue or black. (Kentucky State University, Aquaculture Research Center, 103 Athletic Drive Frankfort, KY 40601, USA; e-mail of D. Yasharian: dyasharian@gwmail.ksu.edu)

INCIDENCE OF WHITE MUSCLE DISEASE, A VIRAL LIKE DISEASE ASSOCIATED WITH MORTALITIES IN HATCHERY-REARED POSTLARVAE OF THE GIANT FRESHWATER PRAWN MACROBRACHIUM ROSENBERGII (DE MAN) FROM THE SOUTH-EAST COAST OF INDIA
K. K. Vijayan, V. Stalin Raj, S. V. Alavandi, V. Thillai Sekhar, T. C. Santiago-2005
Aquaculture Research, 36 (3): 311-
Abstract:
Incidence of post-larval mortalities of 30 100% was reported from commercial freshwater prawn, Macrobrachium rosenbergii (De Man) hatcheries in Andhra Pradesh and Tamil Nadu (south-eastern states of India) since 2001. Infected postlarvae (PL) exhibited clinical symptoms with lethargy, anorexia and whitening of abdominal muscles and the disease was identified as white muscle disease (WMD). The waterborne infection of WMD was induced in the laboratory by exposing uninfected and healthy M. rosenbergii PL to the filtered muscle homogenates of the naturally infected PL, resulting in mortality that reached 99% within 10 days post infection. Histopathological examination of the infected animals revealed highly necrotic musculature. Degenerated muscle areas showed aggregations of melanized nuclei, many of which looked like inclusion bodies. Bacteriological examination of affected PL showed the presence of Staphylococcus spp. as a predominant organism, while laboratory challenge of healthy PL with this bacterial isolate did not reproduce WMD. (Central Institute of Brackishwater Aquaculture (CIBA), 75 Santhome High Road, Chennai 600028, India; e-mail of K. K. Vijayan: kkvijayan@hotmail.com)

SHORT COMMUNICATION: REARING OF SQUID HATCHLINGS, HETEROLOLIGO BLEEKERI (KEFERSTEIN 1866) UP TO 2 MONTHS IN A CLOSED SEAWATER SYSTEM Yuzuru Ikeda, Ikuko Sakurazawa, Kingo Ito, Yasunori Sakurai, Gen Matsumoto-2005 (Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan, email of Y. Ikeda: ikeda@sci.u-ryukyu.ac.jp)

DIETARY VITAMIN A REQUIREMENTS OF JUVENILE JAPANESE FLOUNDER PARALICHTHYS OLIVACEUS
L.H.H. Hernandez, S.-I. Teshima, , M. Ishikawa, S.A lam, S. Koshio, Y. Tanaka -2005
Aquaculture Nutrition, 11 (1): 3-
Abstract:
A 70-day feeding experiment was conducted to assess the dietary vitamin A (VA) requirements of juvenile Japanese flounder (Paralichthys olivaceus). Six semi-purified diets with VA supplementations of 0, 5000, 10 000, 15 000, 20 000 and 25 000 IU kg 1 were fed twice a day to triplicate groups of 20 juveniles per tank with an initial weight of 1.59 ± 0.01 g (mean ± SE). Weight gain (WG) and specific growth rate (SGR) increased as dietary VA increased up to 10 000 IU kg 1. Significantly lower WG and SGR were observed for the 0 IU kg 1 treatment than for treatments of 5000, 10 000 and 15 000 IU kg 1. Highest WG and SGR were observed in fish fed 10 000 IU kg 1; slightly lower values were recorded in fish fed 15 000, 20 000 or 25 000 IU kg1. No significant difference was observed in survival rate among treatments. Whole body total lipid was significantly higher in fish fed 0 and 5000 IU kg 1 than for other levels. Reduced growth and small livers were observed as signs of VA deficiency in fish fed 0 IU kg 1. Slightly reduced growth and pale fragile livers were observed as effects of VA excess in fish fed 25 000 IU kg 1. Total retinol contents in liver and eyes increased with increasing levels of dietary VA. No retinol was detected in livers, and significantly lower total retinol content was observed in eyes, of fish fed 0 IU kg 1. WG analysed by the broken line method indicated that an optimum dietary VA requirement of 9000 IU kg 1. (Laboratory of Aquatic Animal Nutrition, Faculty of Fisheries, Kagoshima University, Shimoarata 4-50-20, Kagoshima, 890-0056, Japan; email of H.H. Hernandez, luis.hector@angel.fish.kagoshima-u.ac.jp)

EFFECTS OF VARYING DIETARY PROTEIN LEVELS ON GROWTH, REPRODUCTIVE PERFORMANCE, BODY AND EGG COMPOSITION OF ROHU, LABEO ROHITA (HAMILTON) M. Afzal Khan, A.K. Jafri, N.K. Chadha -2005
Aquaculture Nutrition, 11 (1): 11-
Abstract:
A 360-day feeding trial was conducted to observe the influence of varying levels of dietary protein on growth, reproductive performance, body and egg composition of rohu, Labeo rohita. Twenty fish (40.4 ± 0.24 cm; 852 ± 4.9 g), stocked in outdoor concrete tanks (200 m2), in duplicate, were fed diets with varying levels (200, 250, 300, 350 and 400 g kg 1) of crude protein exchanged with carbohydrate to apparent satiation, twice daily, at 09:00 and 17:00 h. Higher (P < 0.05) weight increment was discernible in fish fed dietary protein 300 g kg 1. Gonadosomatic index was comparable (P > 0.05) among fish of different dietary groups except those fed 200 g kg 1 protein diet which produced least values. Egg diameter remained unaffected (P > 0.05) by variations in levels of dietary protein. Relative fecundity was maximum (P < 0.05) in fish fed 250 and 300 g kg 1 protein diets. With the exception of fish fed 200 g kg 1 protein diet, fertilizability (%) remained unaffected (P > 0.05) by variations in dietary protein level. Hatchability (%) followed the trend of variations almost similar to that of fertilizability. Proximate composition of muscle and eggs varied significantly (P < 0.05) with dietary protein levels. For broodstock L. rohita, a dietary protein level of 250 g kg 1 was found optimum with regard to its reproductive performance, egg quality and composition. (Fish Nutrition Research Laboratory, Department of Zoology, Aligarh Muslim University, Aligarh-202 002, India; email of M. Afzal Khan: khanmafzal@yahoo.com)

EFFECT OF MICROALGAL BIOMASS CONCENTRATION AND TEMPERATURE ON ORNAMENTAL GOLDFISH (CARASSIUS AURATUS) SKIN PIGMENTATION
L. Gouveia, P. Rema-2005
Aquaculture Nutrition, 11 (1): 19-
Abstract: The aim of this work was to investigate the effect of different carotenoid sources/concentrations and temperature on goldfish (Carassius auratus) skin pigmentation. In the first trial (trial A), the effect of carotenoid source (natural microalgae Chlorella vulgaris and synthetic Carophyll Pink) and carotenoid concentration (45, 80 and 120 mg pigment kg 1 diet) was tested. Six homogeneous duplicate groups of juvenile goldfish (7.4 g) were fed, for 5 weeks, one of the diets containing 45, 80 or 120 mg of total pigments of C. vulgaris biomass or synthetic astaxanthin per kg of diet (Cv45, Cv80, Cv120, Ax45, Ax80, Ax120), respectively. In trial B, the effect of water temperature on skin pigmentation was studied. Five homogeneous duplicate groups of 25 goldfish each (5.2 g) were fed diet Ax45 over 9 weeks, to test the following temperatures: 22, 24, 26, 28 and 30 °C. At the end of both trials, samples of skin along the dorsal fin were withdrawn for subsequent analysis of total carotenoid content, intensity of colour, red and yellow hue and visual observation. The best carotenoid concentrations were achieved with astaxanthin diets. There was a tendency to an overall improvement of colour parameters (L and b) in fish fed diets with high levels of C. vulgaris. The results indicated that the best temperature range to maximize skin pigmentation was 26 30 °C. (Instituto Nacional de Engenharia e Tecnologia Industrial-INETI-DER. Estrada do Paço do Lumiar, N° 22, edifício G, 1640-038 Lisboa, Portugal; email of L. Gouveia,: luisa.gouveia@ineti.pt)

MATERNAL AND SEASONAL DIFFERENCES IN EGG SIZES AND SPAWNING ACTIVITY OF NORTHWEST ATLANTIC HADDOCK (MELANOGRAMMUS AEGLEFINUS) IN RELATION TO BODY SIZE AND CONDITION
Edward A. Trippel, Steven R.E. Neil-2004
Can. J. Fish. Aquat. Sci., 61(11): 2097-2110
Abstract:
Egg and larval production of 22 captive spawning pairs of northwest Atlantic haddock (Melanogrammus aeglefinus) were monitored. Females spawned an average of nine egg batches (range 3–16) with a mean batch fecundity of 60 000 eggs and mean total fecundity of 535 000 eggs. Mean spawning duration was 37 days with a mean batch interval of 5.4 days. In multiple linear regression, male Fulton's condition factor (range 1.10–1.55) and mean batch interval explained 56% of variation in fertilization rate (33% and 23%, respectively). Seasonal composite egg diameter spanned 1.37–1.53 mm among females. Mean egg diameter within females declined seasonally by an average of 10.4% (37% by volume). Females produced 46 larvae per gram body weight. Body weight was the single best predictor of fecundity (r2=0.57), with Fulton's condition factor (range 1.04–1.76) explaining no significant additional variation over length or weight. Length and condition explained 39% of variation in seasonal composite egg diameter (22% and 17%, respectively) and body weight independently explained 32%. Sex-specific parental condition and body size acted through large egg size and elevated fertility to enhance reproductive output. Male spawning success was more sensitive than egg production to changes in condition.

PREDATOR-RECOGNITION TRAINING OF HATCHERY-REARED WALLEYE (STIZOSTEDION VITREUM) AND A FIELD TEST OF A TRAINING METHOD USING YELLOW PERCH (PERCA FLAVESCENS)
Brian D. Wisenden, Josh Klitzke, Ryan Nelson, David Friedl, Peter C. Jacobson-2004
Can. J. Fish. Aquat. Sci., 61(11): 2144-2150
Abstract:
Fishes reared in captivity are predator-naïve and suffer large predation mortality when stocked into lakes with a full complement of predators. We tested the potential of predator training to enhance post-stocking survival of hatchery-reared walleye (Stizostedion vitreum). In the first part of the study, we found that walleye (i) use chemical cues for assessing predation risk, (ii) do not have innate recognition of the odor of northern pike (Esox lucius) as an indicator of predation, and (iii) associate predation risk with pike odor after a single simultaneous encounter with pike odor and chemical alarm cues from walleye skin. In the second part of the study, we attempted to mass-train yellow perch, Perca flavescens (as a surrogate for walleye), to fear pike odor. Perch response to pike odor was not changed by placing sponge blocks containing pike odor and perch alarm cues around the perimeter of a pond. On pre- and post-training assays, perch avoided traps scented with perch alarm cues, but did not avoid traps labeled with pike odor or water. We conclude that recognition training offers potential as a management tool for walleye, but significant logistic challenges must be solved before it can be implemented.

LONG-RESIDENCE GROUNDWATER EFFECTS ON INCUBATING SALMONID EGGS: LOW HYPORHEIC OXYGEN IMPAIRS EMBRYO DEVELOPMENT
A.F. Youngson, I.A. Malcolm, J.L. Thorley, P.J. Bacon, C. Soulsby-2004
Can. J. Fish. Aquat. Sci., 61(12): 2278-2287
Abstract:
Atlantic salmon (Salmo salar) ova were incubated at a range of burial depths (50–300 mm) in a set of test arrays inserted at previously used redd sites in a near-pristine stream. Oxygen saturation and electrical conductivity of hyporheic water (obtained 0.5–1.0 m distant from each array from a depth of 200–300 mm below streambed level) were determined at ~2-week intervals over the incubation period (November–March). The test arrays were recovered from the streambed in mid-March, and thereafter, the eyed ova were incubated in surface water until hatch (24 March – 17 April). Embryo survival rates, hatch date, and alevin size differed among and within arrays. Mean alevin body size varied markedly among incubation groups (length, 14.9–20.8 mm; dry mass, 3.9–7.7 mg). Within arrays, embryo size varied with burial depth on fine spatial scales (approximately 50 mm); greater burial depth tended to be associated with smaller size. Among arrays, embryo size at the 250-mm depth was correlated with oxygen saturation of hyporheic water. Across all sites, oxygen saturation of hyporheic water decreased with greater conductivity, indicative of the presence of groundwater. Variation in embryo size was therefore linked with variation in the local dominance of deoxygenated groundwater in the hyporheic zone.

ANNUAL CHANGES IN OVARIAN DEVELOPMENT AND PLASMA ESTRADIOL-17 LEVEL IN REARED FEMALE COMMON JAPANESE CONGER, CONGER MYRIASTER
Tomoko Utoh, Noriyuki Horie, Naomi Mikawa, Akihiro Okamura, Yoshiaki Yamada, Atsushi Akazawa, Satoru Tanaka, Hideo P. Oka -2005 Fisheries Science, 71 (1): 38- Abstract:
Annual changes in the gonadosomatic index (GSI), oocyte diameter, gonadal histology and plasma estradiol-17 (E2) levels were investigated in female common Japanese conger Conger myriaster in captivity. Juveniles were caught in September 1999 and reared in seawater at temperatures ranging from 10 20°C for 3 years. All fish were immature when captured in September 1999. GSI and oocyte diameter increased from October 2000, peaked between summer and autumn 2001, and bottomed-out in winter 2001. Plasma E2 level also increased from October 2000, but remained high. The ovarian developmental stage was at the peri-nucleolus stage or the oil droplet stage until September 2000. Vitellogenesis started in October 2000 and oocytes progressed to the tertiary yolk globule stage by summer 2001. However, vitellogenic oocytes regressed in all females after autumn 2001. The neogenetic oocytes began to increase after November 2001 and ovarian development progressed in 2002 as they did in 2001, although maximum GSI in 2002 was half its 2001 value. These data indicate that ovarian development in the common Japanese conger has an annual periodicity, and that these congers may be able to spawn in multiple years under rearing condition. (IRAGO Institute, Atsumi, Aichi 441-3605, Japan, email of T. Utoh: utou@irago.co.jp)

THYROID HORMONE DEFICIENCY IN ABNORMAL LARVAE OF THE JAPANESE FLOUNDER PARALICHTHYS OLIVACEUS Nozomi Okada, Tetsuo Morita, Masaru Tanaka, Masatomo Tagawa -2005
Fisheries Science, 71 (1): 107-
Abstract:
In large-scale rearing of juveniles of the Japanese flounder Paralichthys olivaceus, a certain morphological abnormality occurred spontaneously in 4% of the fish. These fish showed a slight but clearly different appearance from any developmental stage of this species, and did not settle when all the other juveniles in the same tank completed metamorphosis and had settled. From comparisons of external and internal structures between the normal and the abnormal fish, the abnormality was attributed to unbalanced progress of metamorphosis, mainly due to metamorphic stasis. The thyroid of the abnormal fish was apparently activated morphologically. In addition, serum thyroxine (T4) concentrations in the abnormal fish were reduced to less than 1/10 of that of normal fish. After 14 days of T4 treatment (0.1 p.p.m) of the abnormal fish, all the abnormal characteristics disappeared, and the fish recovered to normal, suggesting normal responsiveness to thyroid hormones in peripheral tissues, whereas thiourea treatment (30 p.p.m., 14 days) further delayed metamorphosis. These results suggest that these abnormal fish were suffering from thyroid hormone deficiency, and were unable to secrete a sufficient amount of thyroid hormone to complete metamorphosis. (Hokkaido Central Fisheries Experimental Station, Yoichi, Hokkaido 046-8555, Japan; email of N. Okada: okadan@fishexp.pref.hokkaido.jp)

OPTIMUM DIETARY PHOSPHORUS LEVEL OF JUVENILE JAPANESE FLOUNDER PARALICHTHYS OLIVACEUS REARED IN THE RECIRCULATING SYSTEM Xiaojie Wang, Semin Choi, Sanghee Park, Gwangyeol Yoo, Kangwoong Kim, Ju-Chan Kang, Sungchul C. Bai -2005
Fisheries Science, 71 (1): 168-
Abstract:
An 8-week feeding trial was conducted to determine the optimum dietary phosphorus level of juvenile Japanese flounder Paralichthys olivaceus reared in the recirculating system. The basal diet containing 0.33% total phosphorus (TP) was supplemented with NaH2PO4•H2O to provide 0.33, 0.51, 0.71, 0.94, 1.10 and 2.12% TP for the experimental diets. Fish averaging 2.0 ± 0.04 g (mean ± SD) were fed in triplicate groups with the experimental diets for 8 weeks. After 8 weeks, fish fed the 0.51% TP diet showed significantly higher weight gain (WG), feed efficiency (FE), specific growth rate (SGR), and protein efficiency ratio (PER) than those fed the 0.33% and 2.12% TP diets (P < 0.05). Meanwhile, no difference was observed in WG, FE, SGR and PER of fish fed the 0.51, 0.71, 0.94 and 1.10% TP diets. Fish fed the 0.33% TP diet showed phosphorus deficiency symptoms such as poor growth and a deformed head by the end of 8 weeks. Ash and phosphorus contents of bone increased with the increase of dietary phosphorus concentrations. ANOVA test, the quadratic regression analysis, and the broken line analysis suggested that the optimum dietary phosphorus level could be between 0.45 and 0.51% TP for maximum WG in juvenile Japanese flounder. Department of Aquaculture/Feeds & Foods Nutrition Research Center, Pukyong National University, Nam-Gu, Busan 608-737, Korea; email of S.C. Bai: scbai@mail.pknu.ac.kr)

ZOOPLANKTON DISTRIBUTION IN FOUR PONDS OF DIFFERENT SALINITY: A SEASONAL STUDY IN THE SOLAR SALTERNS OF SFAX (TUNISIA)
Néji Toumi, Habib Ayadi, Olfa Abid, Jean-François Carrias, Télesphore Sime-Ngando, Mekki Boukhris, Abderrahmen Bouain-2005
Hydrobiologia, 534 (1-3): 1-9
Abstract :
The seasonal distribution of metazooplankton and large-sized ciliates was studied in four ponds of different salinity in the solar salterns of Sfax (Tunisia). Total zooplankton abundance varied from 1 × 103 to 4.7 × 106 ind m–3. Salinity had a negative effect on the abundance of copepods and rotifers which were absent in the pond with the highest salt concentration (180ppt) in which the number of taxa was low and Artemia or the ciliate Fabrea largely dominated the zooplankton community. Temperature and the presence of Dunaliella salina as prey appeared as key factors in controlling the abundance of Artemia, while organic detritus appeared as important in the diet of Fabrea. Change in zooplankton species composition along the hypersaline gradient (40–90ppt) was primarily related to salinity. However, our data suggest the importance of both the abundance and composition of food in the spatial and temporal variations of some zooplankton species. (Laboratoire d Ecologie Planctonique, Faculté des Sciences de Sfax, Route Soukra, Km 3.5, 3038 Sfax, Tunisie, email of Jean-François Carrias:
J-Francois.CARRIAS@lbp.univ-bpclermont.fr)

FREE FATTY ACIDS AND STEROLS IN THE BENTHIC SPAWN OF AQUATIC MOLLUSCS, AND THEIR ASSOCIATED ANTIMICROBIAL PROPERTIES
Kirsten Benkendorff, Andrew R. Davis, Cary N. Rogers, John B. Bremner-2005 Journal of Experimental Marine Biology and Ecology, 316 (1): 29-44
Abstract:
The free lipid content of extracts from the spawn of 17 molluscs were analysed by gas chromatography/mass spectrometry. These extracts encompass the encapsulated embryos and extraembryonic structures from benthic gelatinous egg masses and leathery egg capsules covering five taxonomic groups. Palmitic and stearic acids were the dominant saturated fatty acids and oleic acid was the principal unsaturated acid found in the spawn. Cholesterol was the dominant sterol and the only sterol found in the spawn from every species. Extracts from gelatinous egg masses were found to contain proportionally more fatty acids compared to leathery egg capsules. No unsaturated fatty acids were found in any of the leathery egg capsules, including five neogastropods and one littorinimorph. Unsaturated fatty acids were present in all of the gelatinous egg masses, including two other littorinimorphs. This is the first study to demonstrate that unsaturated fatty acids possess significant bacteriolytic activity against four aquatic pathogens. Encapsulated Anaspidea egg masses contain relatively high concentrations of these unsaturated fatty acids and a lipid mixture modeled on these extracts was strongly bacteriolytic at concentrations down to 0.0001 mg/ml. By comparison, lipid mixtures modeled on extracts from the spawn of four other molluscan taxa with higher proportions of saturated fatty acid and cholesterol, were only partially active against some of the bacteria at 0.1 mg/ml. Thus, unsaturated fatty acids could explain the antimicrobial activity previously reported in lipid extracts of some, but not most, molluscan spawn. MDS ordination and ANOSIM revealed significant taxonomic differences in the composition of free lipids from molluscan spawn, suggesting that lipid analyses may be useful in future systematic studies of the Mollusca.
(School of Biological Sciences, The Flinders University of South Australia, GPO Box 2100, Adelaide, 5001, Australia; email of Kirsten.Benkendorff: kirsten.benkendorff@flinders.edu.au)

PRELIMINARY OBSERVATIONS OF TOPICAL GILL APPLICATION OF REPRODUCTIVE HORMONES FOR INDUCED SPAWNING OF A TROPICAL ORNAMENTAL FISH
Jeffrey E. Hill, John D. Baldwin, Jeffrey S. Graves, Robert Leonard, James F. F. Powell-2004
Craig A. Watson
North American Journal of Aquaculture, 67 (1): 7–9
Abstract:
Hormone injection is a common spawning induction technique in aquaculture but is of limited use in small species with low fecundity. An alternative to injection for such species is topical gill application. We conducted an experiment with female rainbow sharks Epalzeorhynchos erythrurus (Cyprinidae) in one control group and three treatment groups: (1) topical gill application of dimethyl sulfoxide (DMSO), (2) topical gill application of DMSO and Ovaprim, and (3) an Ovaprim intramuscular (IM) injection. Ovaprim contains a salmonid gonadotropin-releasing hormone analog and a dopamine antagonist. Fish were anesthetized, treated, and placed into recovery tanks. Fish were manually checked for ovulation by exerting abdominal pressure at 8, 10, and 11 h posttreatment and were observed for mortality during a 24-h period. Ovulation varied significantly: we found no ovulation of females in the control or DMSO groups, 78% ovulation in the DMSO plus Ovaprim group, and 100% ovulation in the Ovaprim IM injection group. Only two mortalities occurred in 24 h, both in the injected group. Use of DMSO as a solvent for topical gill application of hormones shows some promise as a spawning induction technique for tropical ornamental fishes.
(Tropical Aquaculture Laboratory, Institute of Food and Agricultural Sciences, University of Florida, 1408 24th Street Southeast, Ruskin, Florida 33570, USA)

GROWTH OF POSTLARVAL MACROBRACHIUM ROSENBERGII AT TWO TEMPERATURES
F. C. Arana-Magallón, A. A. Ortega-Salas-2004
North American Journal of Aquaculture, 67 (1): 10–12
Abstract.:
Postlarvae of the giant Malaysian prawn Macrobrachium rosenbergii were reared for a 120-d period under laboratory conditions at 20°C and 33°C. We stocked 480 50-d-old postlarvae in eight 70-L aquaria. A balanced commercial feed containing 40% protein was supplied daily at 20% to 9% of body weight during the first 2 months and at 5% to 3% of body weight during the final 2 months. Live brine shrimp Artemia franciscana were also provided as a supplemental food. The growth of the giant Malaysian prawn was significantly greater at 33°C than at 20°C. Basic knowledge of giant Malaysian prawn rearing requirements under artificial conditions is important for the production of juveniles as stocks for large-scale prawn culture.
(Departamento del Hombre y su Ambiente, Universidad Autónoma Metropolitana, Xochimilco, Calzada del Hueso 1100, Villa Quietud, México 04960, Distrito Federal, México)

A SIMPLE ISOLATION INCUBATOR FOR SPECIALIZED REARING OF SALMONID EGGS AND FIRST-FEEDING FRY
Jeff A. Heindel, Danny J. Baker, Keith A. Johnson, Paul A. Kline, Jeremy J. Redding-2004
North American Journal of Aquaculture, 67 (1): 13–17
Abstract:
The construction of an isolation incubator for small-scale fish culture and research is described. The simple, inexpensive (US$5) isolation incubator is routinely used to incubate as many as 100 green eggs of sockeye salmon Oncorhynchus nerka and Chinook salmon O. tshawytscha through the first-feeding fry stage of development at the Idaho Department of Fish and Game's Eagle Fish Hatchery. The incubator is small (2.5-L volume) and portable, requires a small amount of water per individual unit (500–1,200 mL/min), and provides a way to incubate multiple rearing groups in a quarantine environment through the early stages of fish development. Although these incubators have been used exclusively for incubation of salmonid eggs and fry, we expect this design can be used to successfully incubate eggs of other fish species.
(Idaho Department of Fish and Game, Eagle Fish Hatchery, 1800 South Trout Road, Eagle, Idaho 83616-5661, USA)

A SIMPLE ASSAY TO COMPARE ZEOLITE AMMONIA CONTROL PROPERTIES
Andrew J. Mitchell-2004
North American Journal of Aquaculture, 67 (1): 18–22
Abstract:
Zeolites purchased from aquaculture industry suppliers vary in their ability to remove ammonia, and little information is provided about their origin, type, and purity. To evaluate them, a simplified method for comparing their ammonia control properties was developed. Ammonia levels from water treated with five different zeolites were effectively measured and compared with two different inexpensive total ammonia nitrogen (TAN) test kits using the same procedure. I found that 10 g of a zeolite added to and stirred in an ammonia solution (0.1 g of ammonium sulfate dissolved in 1 L water) for 20 min produced TAN levels within the readable ranges for the Hach Model NI-8 and NI-SA ammonia nitrogen test kits; a 1:6 dilution of the ammonia test solution was made just before the TAN analysis. The TAN readings after the addition of the five zeolites ranged from 1.2 to 2.6 mg/L (multiplying by 7 to get actual TAN readings is not necessary to compare zeolites) for the Model NI-8 kit. The Model NI-SA kit gave the same relative results but had readings that were 0.5–0.7 mg/L lower; in the case of these kits the obtained precision was more important than their accuracy.
(H. K. Dupree Stuttgart National Aquaculture Research Center, U.S. Department of Agriculture, Agricultural Research Service, Stuttgart, Arkansas 72160, USA)

BACTERIAL NUMBERS FROM LANDLOCKED FALL CHINOOK SALMON EYED EGGS SUBJECTED TO VARIOUS FORMALIN TREATMENTS AS DETERMINED BY SCANNING ELECTRON MICROSCOPY AND BACTERIOLOGICAL CULTURE METHODS
Michael E. Barnes, David Bergmann, Hans Stephenson, Mark Gabel, Rick J. Cordes-2004
North American Journal of Aquaculture, 67 (1): 23–33
Abstract:
This study compared two methods of enumerating bacteria adhered to the external membrane of eggs of landlocked fall Chinook salmon Oncorhynchus tshawytscha that were subjected to different formalin treatment regimes from egg eye-up to fry hatch. Bacterial numbers were recorded by either directly counting bacteria via a scanning electron microscope (SEM) or via established bacterial culture methods that provided the number of colony-forming units. Treatment regimes consisted of a daily 15-min exposure to formalin at either 500 mg/L or 1,667 mg/ L or no formalin initially followed by exposure to a 1,667-mg/L dose starting 7 d after eye-up. A control group did not receive any formalin treatments throughout the experiment. No significant correlation was observed between the number of colony-forming units (CFUs) per square millimeter of egg membrane determined by plate culture and the number of bacteria per square millimeter counted with the SEM. Bacterial numbers determined by the SEM were 40–120 times greater than those obtained by plate culture. The SEM numbers were correlated to embryo survival, but CFU numbers were not. For both counting methods, bacterial numbers among the untreated controls increased over time. Of the three species of bacteria identified in cultures (Flavobacterium columnare, Sphingobacterium spp., and Pseudomonas spp.), F. columnare was predominant. Embryo survival in the trays that did not receive any formalin was significantly less than that in all of the other treatments, but there was no significant difference in survival among any of the three formalin treatment regimes.
(South Dakota Department of Game, Fish and Parks, McNenny State Fish Hatchery, 19619 Trout Loop, Spearfish, South Dakota 57783, USA)

AN EXTENDER SOLUTION FOR THE SHORT-TERM STORAGE OF STURGEON SEMEN
Chulhong Park, Frank A. Chapman-2004
North American Journal of Aquaculture, 67 (1): 52–57
Abstract:
An extender solution was developed to prolong the time that semen from sturgeons could be stored in the refrigerator, thus greatly improving the artificial propagation of these species for purposes of conservation and commercial aquaculture. Semen from Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi and shortnose sturgeon A. brevirostrum was used to develop the extender media. Fresh semen from sturgeon is traditionally stored whole and undiluted in the refrigerator along with pure oxygen. The fertilizing capacity of semen stored in this manner is usually maintained for 12– 36 h. The mixing of fresh semen with an artificial extender solution significantly (P < 0.05) prolonged the refrigerated storage time of spermatozoa and maintained sperm motility for up to 21–28 d at 4°C. No significant differences in fertilization capacity were observed between fresh semen and semen diluted with the extender and stored from 3 to 18 d.
(Department of Fisheries and Aquatic Sciences, University of Florida, Post Office Box 110600, Gainesville, Florida 32611, USA)

MORTALITY OF FISH LARVAE EXPOSED TO VARYING CONCENTRATIONS OF CYCLOPOID COPEPODS
Emmanuel A. Frimpong, Steve E. Lochmann-2004
North American Journal of Aquaculture, 67 (1): 66–71
Abstract:
Cyclopoid copepods can prey on freshwater fish larvae. The magnitude of predation is related to the size and concentrations of the cyclopoid copepods and the size of the fish larva; it is also likely to be specific to certain species. We studied 5-d-old larvae of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis), golden shiner Notemigonus crysoleucas, fathead minnow Pimephales promelas, and goldfish Carassius auratus in four separate experiments. Larvae were stocked at 20/L into 2 L of water containing various concentrations of the cyclopoid copepods Cyclops vernalis and Mesocyclops vericans to ascertain the effect of predation on mortality. We also compared predation rates observed in this study with rates predicted by an empirical model of crustacean predation on fish larvae from the literature. Sunshine bass alone were susceptible to predation mortality at the cyclopoid copepod concentrations used in this study. Mortality at 400 cyclopoids/L was significantly higher than mortality at 0–100 cyclopoids/ L. Mortality at 500 cyclopoids/L was significantly greater than mortality at any other treatment concentration. The observed predation rates were much lower than the predation rates predicted by the model. Stocking sunshine bass larvae at 4.11 mm total length or larger into ponds with fewer than 300 cyclopoids/L probably represents a low risk of predation. Golden shiners, fathead minnow, and goldfish larger than 5 mm total length that are stocked in ponds with fewer than 500 cyclopoids/L would also probably experience little cyclopoid copepod predation.
(Aquaculture/Fisheries Center, University of Arkansas at Pine Bluff, 1200 North University Drive, Mail Slot 4912, Pine Bluff, Arkansas 71601, USA)

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