Indoor Tanks Research Articles

Progress in Controlled Maturation and Spawning of Summer Flounder Paralichthys dentatus Broodstock

Abstract— Wild‐caught, adult summer flounder Paralichthys dentatus (avg. wt. = 740 g; range = 264–1,540 g; N= 60), collected in northeastern US coastal waters during October 1994, were transported to Vero Beach, Florida in March 1995 and held in 2.6‐m3 indoor tanks through November 1995 under two artificial photothermal regimes: (1) natural regime, simulating natural habitat conditions; and (2) accelerated thermal regime, with seasonal temperature changes advanced by one month. A third group of fish was held in outdoor tanks under ambient photothermal conditions. Under all photothermal conditions, onset of vitellogenesis was associated with declining daylength and temperature, beginning in the accelerated group, then progressing to the natural and the ambient groups. From 20 September to 28 November 1995, 23 vitellogenic stage females from the accelerated and natural regimes were implanted with a cholesterol‐cellulose pellet containing LHRH‐a (100 μg/kg body wt). Females with initial mean oocyte diameters ranging from 258–456 μm spawned voluntarily 2.5–5.5 d postimplantation, while no maturational response was obtained from females with mean diameters ranging from 165–231 μm. Two females were spawned twice during the study period by LHRH‐a pellet implantation. Infrequent, natural spawning without hormone intervention was also obtained. Females released from 22.7–396.9 × 103 eggs on the first day of spawning, with fertilization and hatching rates of 0–93.470 and 0–81.1%, respectively.

Body cooling and its energetic implications for feeding and diving of tufted ducks.

Wintering in a temperate climate with low water temperatures is energetically expensive for diving ducks. The energy costs associated with body cooling due to diving and ingesting large amounts of cold food were measured in tufted ducks (Aythya fuligula) feeding on zebra mussels (Dreissena polymorpha), using implanted heart rate and body temperature transmitters. The effects of diving depth and food ingestion were measured in two sets of experiments: we measured body cooling and energy costs of six tufted ducks diving to different depths in a 6-m-deep indoor tank; the costs for food ingestion and crushing mussel shells were assessed under seminatural winter conditions with the same ducks feeding on mussels in a 1.5-m-deep outdoor pond. Body temperature dropped during feeding bouts and increased gradually during intermittent resting periods. The temperature drop increased linearly with dive duration. The rate of body cooling increased with feeding depth, but it was lower again at depths below 4 m. Half of the increment in energy costs of diving can be attributed to thermoregulatory heat production, of which approximately 50% is generated after diving to warm up the body. The excess costs for ducks feeding on large-sized mussels could be entirely explained by the estimated energy cost necessary to compensate the heat loss following food ingestion, suggesting that the heat production from shell crushing substituted for thermoregulation. Recovery from heat loss is probably a major component of the activity budget of wintering diving ducks.

INFORMATION SOURCES, TECHNOLOGIES, TEACHERS' ATTITUDES, AND COMMUNITY IMPACT FROM TEACHING AQUACULTURE IN THE NORTHEASTERN REGION

The purpose was to establish baseline data for all Northeastern secondary agricultural education programs that incorporated aquaculture in the total curriculum during 1996-1997. Perceptions of aquaculture information and training, technologies used, community linkages, and teachers' attitudes towards aquaculture programs were sought from agriculture teachers in 12 states. Respondents (N.=70) indicated the source of their aquaculture information as other agriculture education teachers, conferences, workshops, or courses. A majority of teachers had attended formal training programs such as technical aquaculture courses and aquaculture curriculum workshops. Respondents rated indoor tanks, water quality kit, recirculatory system, aerator, and feeding pellets as very important technologies to an aquaculture program. Agriculture teachers perceived that teaching aquaculture motivated students, but they did not believe an aquaculture program would encourage students to seek a postsecondary education. Northeastern agricultural education programs had very limited crossover between school districts when describing linkages, arrangements, and/or agreements to teach aquaculture. The primary benefits of a collaborative linkage included increased student participation and peer tutoring. The community impacts from teaching aquaculture were described as awareness level activities such as aquaculture facility tours, open houses, and field days. Agriculture teachers rated colleges and universities as important external contributors to aquaculture programs.

The relationship between power output and heart rate in ducks diving voluntarily

Heart rate in response to natural and induced changes in power output was monitored in ducks diving voluntarily to a depth of 1.2 m. Adult lesser scaup ( Aythya affinis) (3 female, 2 male), were trained to make shallow dives in an indoor tank (1.2 m depth) to obtain food. Heart rate was monitored using telemetry, and was determined for the following phases of a dive: predive, descent, feeding, ascent and postdive. Heart rate was found to be unaffected by changes in power output during the various dive phases. Power output by the ducks during a dive decreased when the duck’s buoyancy was reduced 41% by injecting 0.10 kg mercury (Hg) into a bag implanted in the duck’s peritoneal cavity. Calculated mechanical power output during the feeding phase of the dive was reduced 61% by the addition of Hg. Heart rate was recorded before adding Hg, with the Hg in place and after removing the Hg. No significant differences in diving heart rate were observed between ducks with or without Hg in the bag. However, leg beat frequency in the feeding phase of a dive was significantly reduced after filling the bag with Hg. We conclude that the level of power output in ducks diving to the shallow depth of 1.2 m has little influence on heart rate.

Effect of temperature in an intensive nursery system for Penaeus paulensis (Pérez Farfante, 1967)

This study was undertaken to evaluate the influence of temperature (18, 23, 28°C) on survival rate and final weight of Penaeus paulensis postlarvae (PL 10) during a 25-day intensive (1800 PL/m 2) nursery trial in indoor tanks. A survey was also conducted in earthen nursery ponds to evaluate the influence of water temperature on the growth rate of P. paulensis in commercial farms. The survival rate achieved at 18°C was significantly ( P<0.05) lower than that observed at the other two temperatures. Final weight increasing as the temperature increased with the mean weight at 28°C being significantly ( P<0.05) higher than at the other two temperatures. The results showed that low water temperature affects the survival rate of P. paulensis when cultivated at 18°C during the nursery period. Growth rate was positively correlated with water temperature within the range tested. Data from a field survey suggested this positive correlation could be applied to postlarvae cultured in earthen ponds.

Growth of Penaeus vannamei on soils from various Texas shrimp farms, under laboratory conditions

Penaeus vannamei postlarvae (150 mg mean initial weight) were cultured for 80 days in indoor tanks under without substrate or with pond-soil substrate from five Texas shrimp farms; all tanks were provided with natural seawater from the ship channel adjacent to Port Aransas, TX. Final mean weight gain (MWG) of shrimp gain of shrimp for the various substrate treatments ranged from 13.75 to 16.04 g. Shrimp growth on pond-soil substrates in the laboratory was correlated with shrimp production in the ponds from which the soil samples had been taken. Ponds were classified as either `good' or `bad,' depending on their shrimp-production history. MWG of postlarvae on soils from the `good' ponds group was significantly greater than that for the `bad' ponds group. These results demonstrate a substrate impact on shrimp growth independent of water source. In relatively stagnant commercial production ponds, the impact of substrate on shrimp production might be more pronounced than under the flow-through conditions employed in the experiment described here.

Induction of out-of-season spawning in walleye ( Stizostedion vitreum)

Simple environmental and hormonal treatments were used to induce out-of-season spawning in walleye Stizostedion vitreum up to 10 weeks prior to the normal reproductive season. Wild walleye were captured in the autumn, held in earthen ponds, and in late January, February, and March (approximately 10, 6, and 3 weeks prior to natural spawning), 16–20 female and 4–8 male walleye were recaptured and transferred to indoor tanks. Water temperature was raised from 2°C to 10°C over a one week period, and photoperiod held at 12 h light: 12 h dark. The females were injected with either human chorionic gonadotropin (hCG), des-Gly 10 [ d-Ala 6] LHRH-ethylamide (LHRHa), hCG and 17 α,20 β-dihydroxy-4-pregnen-3-one (17,20-P), or saline as a control. Each month, at least some females in each treatment group were successfully induced to ovulate. No control fish ovulated at any time. In January, hCG was the most effective treatment at inducing ovulation (3/5 fish). In February and March, all but one hormone-injected fish ovulated. In general, the eggs collected from fish treated with either hCG or LHRHa were of good quality with overall survival highest in hCG-treated fish. Eggs collected from 17,20-P-treated fish were small and had very low survival. In February and March, serum levels of estradiol-17 β and testosterone were different between fish treated with 17,20-P and those treated with either hCG or LHRHa. Out-of-season spawning could be used to provide walleye fry for intensive culture systems at multiple times of the year, thereby facilitating research on indoor fry culture. In addition, walleye fingerling production could be initiated as early as January, allowing public and private hatcheries to produce larger age-0 walleye fingerlings for stocking than would otherwise be possible.

Enrichment of live food with essential fatty acids and vitamin C: effects on milkfish ( Chanos chanos) larval performance

The effects of essential fatty acids (EFA) and vitamin C-enriched live food on growth, survival, resistance to salinity stress and incidence of deformity in milkfish larvae reared in tanks were investigated. Larvae were either fed rotifers cultured on Chlorella sp. and newly hatched Artemia nauplii (control), highly unsaturated fatty acid (HUFA)-enriched rotifers and Artemia nauplii or HUFA+vitamin C-enriched rotifers and Artemia nauplii. Milkfish growth in outdoor nursery ponds was also assessed to compare with growth in indoor tanks. Milkfish fed rotifers/ Artemia enriched with HUFA (32–48 mg dry weight, DW) or HUFA+vitamin C (33–45 mg DW) exhibited significantly ( P<0.05) higher growth than those given unenriched live food (24–27 mg DW) after 40 days of culture. Growth of milkfish in nursery ponds (albeit lower in stocking density) showed similar trends as those reared in tanks. When subjected to salinity stress (Day 25), mortality of the HUFA+vitamin C-treated fish and HUFA-treated fish were significantly lower ( P<0.05) than the control fish. Survival of 26-day old milkfish, however, did not differ significantly ( P>0.05) among the treatment groups. Forty-day-old milkfish fed HUFA+vitamin C-enriched live food had significantly lower ( P<0.05) incidence of opercular deformity (mainly cleft branchiostegal membrane) (8.4–14.7%) compared with those given HUFA-enriched (15.8–23.5%) or unenriched (27.3–33.5%) live food. Results demonstrated the effect of HUFA enrichment in enhancing milkfish larval growth and resistance to salinity stress but not overall survival. Moreover, HUFA and ascorbate supplementation decreased but did not totally eliminate incidence of opercular deformity in milkfish larvae.

Occurrence of Beko Disease Caused by Microsporidium seriolae (Microspora) in Hatchery-Reared Juvenile Yellowtail.

Hatchery-produced juvenile yellowtail (Seriola quinqueradiata) were transferred from an indoor tank to sea netpens on June 20, June 30, July 10 and July 31, 1995 (4 groups), and each group was monitored at about 10 day intervals for Microsporidium seriolae, the causative agent of beko disease. Water temperature gradually increased during the study period, ranging from 20.8 to 30.2°C. In the first 3 fish groups, almost all fish were found to be infected. However, prevalence of infection in the last fish group was much lower than in the other groups. Groups which were transferred later attained their maximum prevalence of infection within a shorter period. Furthermore, we investigated the effects of water temperature and fish size on the development of M. seriolae in juvenile yellowtail. Two different fish size classes (average body weight 0.3 g and 22.0 g) were infected with M. seriolae to a similar extent. In the histological examination, the development of M. seriolae and host recovery were accelerated in fish reared at 25°C compared to those kept at 20°C.

Artificial ultraviolet-B radiation and cell expansion in the intertidal alga Ulva expansa (Setch.) S. and G. (Chlorophyta)

Growth rates of segments of Ulva expansa (Setch.) S. and G. (Chlorophyta) thallus were measured in an indoor tank under controlled photoperiod and UV-B levels. Growth rates in this tank were lower than those in outdoor tanks used in earlier experiments and the response to UV-B was somewhat different, probably because of differences in ratios of PAR:UV-A:UV-B under the artificial conditions. Plastic and total extension of algal segments were measured under defined tensile loads to determine whether UV-B reduced cell wall extensibility. No significant changes in wall extensibility were measured following exposure of tissues to solar UV-B or a range of artificial doses of UV-B. Osmotic potentials of the cell solution did not vary systematically with treatment, even when growth rates between UV-B-exposed and -unexposed segments were significantly different. These results indicate that the UV-induced reduction in cell expansion is effected by some means other than an inhibition of wall extensibility or a lowering of turgor pressure and argue for a more direct method of control of cell expansion rate.

Precise target strength pattern measurement in an indoor tank.

It is very important to know the target strength (TS) pattern of fish for both an acoustic survey and a design of a quantitative echo sounder. The TS pattern is defined as a function of the tilt angle. There are two methods to measure TS pattern of fish; one is the echo trace analysis method1,2 used for in situ fish, and the other is the controlled method3,4 used for dead, stunned or anaesthetized fish. Echo trace consists of successive echoes returned from the same target. By analyzing the echo trace, the TS pattern and the speed of the target is derived.

Spawning Behavior and Selection of Spawning Substrate.

In order to elucidate the selection of spawning substrate by female cuttlefish Sepia esculenta, their behavior and trigger stimulus during a spawning sequence were examined in indoor tanks. Female approaches substrate, spurts water towards substrate, takes sediment in arms, covers eggs with sediment, spurts water towards substrate again, and undergoes egg deposition on substrate to complete one spawning. Females which finished copulation were visually attracted to more visible substrate. The height of a substrate was not an important factor for the attraction. Substrates which swung by the spurting water were not accepted by females. Females exhibited taking sediment even though there was no sediment on the tank bottom. It was concluded that female cuttlefish prefer long, fine, and immobile materials as spawning substrates.

Artificial seeding of the green seaweed Monostroma for cultivation

In Japan, the green seaweed Monostroma is an important source of humanfood. Monostroma nitidum Wittrock (Japanese name: hitoegusa) is cultivated in brackish waters and estuaries of central to southern Japan. The green seaweed Monostroma grows in the brackish water area in the upper part of the intertidal zone in the warm waters. Artificial seed culture began with the collection of many gametes in April. The resultant zygotes were allowed to adhere to plastic settlement boards (20 cm long and 10 cm wide). The zygoteboards were then cultured in tanks (1 ×2 ×0.5 m) with fertiliser in a controlled growth room (10–87 µmol photon m-2s-1). The cultivated zygotes on the board in the indoor tanks gradually increased in size from 10 to 40 µm in diameter during May to early August. Zygote growth became slowed at the end of August. The zygotesmatured in early September, and the plates were transferred into culture tanks in a dark room for dark treatment. Maturation of the zygote was promoted by providing dark conditions for two weeks. The production of a concentrated zoospore solution from the mature blades was achieved by adding fresh water at temperature 2–3 °C above that of the seeding vats. Zoospores were released in large numbers when exposed to strong irradiance of 100 µmol photon m-2 s-1 for 30 min. The zygotes produced flat unicellular fronds at the germling stage. The technology of artificial seed culture and zoospore release from the zygotes is based mainly on these experiments.

Diving costs as a component of daily energy budgets of aquatic birds and mammals: generalizing the inclusion of dive-recovery costs demonstrated in tufted ducks

Metabolic studies on freely diving birds and mammals are reviewed and allometric relations of diving costs are presented. A distinction can be made between three different types of diving costs: (1) metabolic rate during submergence, relevant in estimating aerobic dive limits, (2) average metabolic rate during diving and breathing intervals (MRd), and (3) diving costs as the excess over resting costs (EDC). EDC is the most comprehensive measure, integrating energy costs over entire dive series with subsequent longer term recovery from heat loss or anaerobic metabolism. Respirometry experiments with tufted duck (Aythya fuligula) diving in a 5.7 m deep indoor tank demonstrated that in this species diving costs, expressed as EDC, increased at lower water temperatures. MRdwas not significantly related to temperature, and probably reflects only the hydrodynamic and not the thermoregulatory component of diving costs. In general, the usual practice of measuring metabolic costs only during diving activity seems insufficient to estimate the total costs of diving. Studies that include longer term recovery (e.g., doubly labelled water measurements over entire foraging trips) yield more complete estimates of diving costs. To take diving costs into account in an animal's energy budget, estimates of EDC are more appropriate than MRd.

Changes in demand feeding behaviour in Arctic charr, Salvelinus alpinus L., caused by differences in dietary energy content and reward level

The objective of this study was to determine whether Arctic charr, Salvelinus alpinus L., are able to adjust their demand feeding behaviour in accordance to differences in dietary energy content (experiment 1) and reward level (amount of food received in response to one trigger actuation) (experiment 2). Fish (initial size 215 g in experiment 1 and 88 g in experiment 2) were reared in 0.8-m3 indoor tanks at commercial stocking densities and fed using demand feeders for 57 and 180 days, respectively. Demand feeding activity did not differ significantly between groups of charr fed diets with a low (19.8 MJ kg-1) gross energy content and those given high-energy (22.0 MJ kg-1) feed. As a result, fish offered the high-energy diets grew significantly faster. The results show that charr held under culture conditions are unable to adjust their demand feeding activity based on the energy content of the food. On the contrary, Arctic charr are able to adjust their demand feeding activity to either low (0.33 g), medium (0.87 g) or high (1.52 g) rewards, and thereby, regulate their food supply to fit their needs. However, it took about 90 days before charr in the low-reward treatment released a daily food ration as high as that released in the high-reward groups. Consequently, there was a significant positive relationship between the size of the reward and final weights. To avoid any depression of initial growth rates, the optimal size of the reward should be 0.1 g per kg fish and trigger actuation.

Technical Notes: Successful First Feeding of Atlantic Halibut Larvae from Photoperiod-Manipulated Broodstock

Abstract Food intake, growth, and survival were determined for larval offspring from a broodstock of Atlantic halibut Hippoglossus hippoglossus maintained on a 6-month delayed photoperiod. The larvae were fed enriched Artemia sp. inan indoor tank. Feeding incidence of larvae increased from 29.0% at 24 h to 91.4% after 4 d; the mean number of ingested Artemia found in the larval guts was 17.7 after 24 h. The myotome height increased significantly from 0.87 ± 0.02 mm at release (day 0) to1.43 ± 0.31 mm at day 15. There was no acute mortality that could be attributed to the transfer from yolk sac incubators, although a 20% mortality was observed between days 3 and 6. In all, 69% of the larvae survived the 15-d experiment. Off-season spawning of the broodstock had no apparent negative effects on the vitality of the larvae with regard to food intake, survival, and growth potential during the first-feeding stages. These results indicate that year-round production of juvenile halibut is feasible.

Preliminary studies on increased survival and accelerated growth of overwintering juvenile abalone, Haliotis discus hannai Ino

Factors concerning the survival and growth rates of juvenile Haliotis discus hannai in winter were investigated during the winter of 1984 and spring of 1985. The results indicated that the small size of juveniles and low water temperatures were important contributing factors to high mortality in northern sea areas of China. A shell length (SL) of 8–10 mm was the critical limit for survival. Most animals less than 8 mm died in winter whether they were held in indoor tanks at ambient temperature or in the sea. Minimal growth occurred during the 5-month period from December to April. Two recirculating systems using elevated temperature control were used to overwinter abalone, with good results. One system consisted of active carbon, coral debris and ultraviolet light (AC.CD.UV) and the other a biomembrane grown on plates of glass-fibre-reinforced plastic (GFRP). The survival rates in the two systems were similar and several times higher than previous reports. After 163 days, the survival rate in the AC.CD.UV system was 66% for 7.1 mm SL (4.0–9.5 mm) juveniles. After 165 days, the survival rate in the GFRP system was 63.4% for 7.3 mm SL (5.0–10.5 mm) juveniles. The daily growth rate was higher in the AC.CD.UV system: 102 μm day −1 for the entire period and 137 μm day −1 during the last 60 days. Thus, at the end of the experiment the abalone were 23.1 mm SL, the biological mass was 16.8 kg m −3 and the density was 3300 individuals m −2. The growth rate in the GFRP system was 54 μm day −1, producing juveniles of 13.2 mm SL.

Sunshine Bass Performance in Ponds, Cages, and Indoor Tanks

Abstract Performances of sunshine bass, the hybrid of female white bass Morone chrysops × male striped bass M. saxatilis, were compared between fish reared in round and rectangular cages in ponds, between fish reared in round and rectangular indoor tanks equipped with biofilters, and between fish reared in ponds without confinement and in rectangular cages in the same ponds. Fish weights at start were 100 ± 5 g, and trials lasted 108 d. Measurements were in terms of density equivalence for cage–cage and tank–tank comparisons and numerical equivalence for cage–pond comparisons. Survival was 100% in all culture units. Mean growth rates in round and rectangular units were similar (2.5 and 2.6 g/d in cages; 2.3 and 2.4 g/d in tanks). Fish grew better in open ponds (2.9 g/d) than in cages in the same ponds (1.4 g!d). Growth and survival of fish in all systems were comparable to reports for palmetto bass (striped bass female × white bass male) and for striped bass.

Hatchery study of the effects of temperature on eggs and yolksac larvae of the Nassau grouper Epinephelus striatus

The effects of temperature on eggs and yolksac larvae of the Nassau grouper ( Epinephelus striatus) were examined under controlled, hatchery conditions. Artificially-fertilized eggs, obtained by induced spawning of captive adults, were stocked (36 eggs per 1) into 15 500 1 cylindroconical indoor tanks at temperatures of 26, 28 and 30 °C, with five tanks per treatment. A salinity of 37 g l −1 and a photoperiod of 12 L: 12 D were maintained. Incubation time to hatching was inversely related to temperature, decreasing from 24.9 h post-fertilization (p.f.) at 26 °C to 20.4 h p.f. at 30 °C, but hatching success (avg. = 82.5%) did not vary with temperature. Survival of pre-feeding larvae declined more rapidly at the higher temperatures to 91.4, 80.7 and 42.2% by Day 1 p.h. at 26, 28 and 30 °C, respectively, indicating that early survival was influenced by factors unrelated to feeding. Development time to the first-feeding stage was inversely related to temperature, decreasing from 86 h p.f. (2.54 d p.h.) at 26 °C to 71 h p.f. (2.11 d p.h.) at 30 °C. Lower temperatures delayed starvation, with survival falling to 32.3, 9.3 and 1.2% by Day 4 p.h. at 26, 28 and 30 °C, respectively. A temperature of 26 °C is deemed advantageous to higher temperatures for incubating eggs and for rearing first-feeding larvae, although even lower temperatures may be feasible. Temperatures within an ecological range can markedly influence development rates of E. striatus eggs and yolksac larvae and hence, dispersal potential, first-feeding and survival in the field.

Technical Notes: Survival of Golden Shiner Fry Fed a Microparticulate Diet

Abstract Growth and survival were compared for fry of' golden shiner (Notemigonus crysoleucas) reared in indoor tanks and fed different sizes of a commercially available dry fry feed. The 3–4-d-old fry were stocked in 80-L tanks at 50 fry/L and were fed to excess 12 times daily for 7 d with Fry Feed Kyowa B-250 (particle size < 250 μm), B-400 (250–400 μm), or B-700 (400–700 um). For fry fed FFKB-250, FFKB-400, and FFKB-700, survival averaged 46.4%, 7.0%, and 1.4% and final total lengths averaged 5.4, 5.1, and 4.7 mm, respectively. Survival was significantly (P < 0.05) higher for fry fed the FFKB-250 diet. Unfed fry did not survive beyond 7 d posthatch.