CINEMar/Open Ocean Aquaculture Annual Progress Report for the period 1/01/03 through 12/31/03
Principal Investigator: Dr. David Berlinsky and Dr. David Fredrikkson
I. Accomplishments
A. Scheduled Tasks
- Determine optimal feeding frequency for juvenile Atlantic halibut
- Document the presence of feed anticipatory activity in juvenile Atlantic halibut
- Utilize an acoustic stimulus to condition Atlantic halibut to the presence of food
B. Progress on Tasks
1. Optimal Feeding Frequency
Juvenile halibut (n = 240; 20g) were purchased from R & R Finfish Development, Ltd. (Nova Scotia, Canada) in February 2003. Fish were placed into nine-100 L, circular tanks incorporated in a recirculating sea water system, at the Aquaculture Research Center (ARC), Zoology Department, UNH. Water temperature was held at 13 + 1°C and artificial lighting was provided (300 lx). Water quality parameters (pH, temperature, salinity, ammonia, nitrite, alkalinity, and dissolved oxygen) were monitored weekly.
Experiment 1A- Optimal feeding frequency during a 24-hour period (constant light)
To investigate the optimal feeding frequency for juvenile halibut during a 24 h period under constant light (24L:0D), fish (n = 20; 25 + 0.5 g) were fed one, three or five times daily (Experiment 1A; Table 1). At the end of the 84 d experiment, specific growth rate (SGR), feed conversion ratio (FCR), total feed consumption, body weight consumed per day (BWCd-1) and coefficient of variation of size (CV) were determined.
Experiment 1B - Feeding Frequency during a 12-hour period (long day)
To examine the growth of juvenile Atlantic halibut during a simulated long-day photoperiod (14L:10D), fish (n = 10; 75.4 + 1.0 g) were fed. (Experiment 1B; Table 1). At the end of the experiment SGR, FCR, total feed consumption, BWCd-1 and CV were determined.
Experiment 1C - Optimal feeding frequency during simulated winter conditions
To examine growth of juvenile halibut during simulated, winter conditions (5 + 1°C; 9L:15D), fish (n = 17; 311 + 3.6 g) were maintained for 84 d in six 1550 L circular tanks which were part of a recirculating system. Fish were hand-fed to satiation (5 mm pellets 58% protein, Dana Feed A/S, Horsen, Denmark) once every other day or once every three days. At the end of the experiment, SGR, FCR, total feed consumption and CV were determined.
Data Analysis
Differences in weight, SGR, FCR, total feed consumed and BWCd-1 between treatments were tested using a one-way ANOVA using SYSTAT 10.0. When significant differences were detected (p < 0.05), Tukey’s HSD-test was used for post-hoc comparisons.
2. Feed Anticipatory Activity
The following experiments were designed to investigate the locomotor activity rhythms of juvenile halibut exposed to different light regimes when fed a single daily meal. Fish in all experiments were conditioned for 30 d using the experimental conditions below prior to the onset of the experiment. After the 30 d conditioning phase, juvenile halibut (n = 10; < 200g) were transferred to a 208 L cylindrical tank with overhead lighting (300 lx) and acclimated for three days prior to the initiation of the experiment. A Macintosh PowerPC 7500/100 running BTV pro/Motion App (Bensoftware, London, England) was used in conjunction with a video camera (3.6mm lense, Model RHP-320WP, Rockhouse Products, Middleton, NY) for data acquisition. When a specified activity threshold was met, the information was recorded by the computer and stored as a text file for further statistical analysis.
Experiment 2A - The presence of feed anticipatory activity of juvenile Atlantic halibut under a 24L:0D photoperiod
To investigate the presence of feed anticipatory activity (FAA) under a 24L:0D photoperiod, juvenile halibut (85 + 1.7 g) were monitored for 24 hours each day. Fish were fed by automatic feeders at 0900 h from June-August, 2002 and monitored for three day intervals and at 0800 h during May-August, 2003 and monitored for seven day intervals.
Experiment 2B - The presence of feed anticipatory activity of juvenile Atlantic halibut under a 12L: 12D photoperiod
To investigate the presence of FAA under a reduced photo-regime (12L:12D; lights on at 0600h and off at 1800h), juvenile halibut (85 + 1.7 g) were monitored at the UNH Coastal Marine Laboratory (CML), Newcastle, NH. Fish were fed at 0800 h by automatic feeders and monitored for five-day intervals.
Data Analysis
The activity records were converted into Microsoft Excel and placed into one-minute segments. For visualization of behavior, the data were double plotted, where each point represented a relative activity level. An increase in activity prior to feeding was an indicator of FAA.
3. Acoustic Conditioning
Juvenile Atlantic halibut (n=30/tank; 141.1 + 10.9 g) were distributed into two 1550 L tanks at the ARC. Water temperature was held constant at 10 + 1°C and photoperiod was maintained at 12L:12D. Water quality parameters (pH, salinity, alkalinity, ammonia, nitrite, temperature) were monitored bi-weekly.
Feed chutes were constructed from PVC and suspended above the tanks to eliminate ambient noise by feed delivery. Feed sampling boxes were constructed to collect the unconsumed feed that sank to the bottom of the tanks. The boxes were covered with netting to prevent fish access to the feed once it settled. An acoustic waterproof speaker was placed inside the experimental tank and delivered a 300 Hz tone for 10 seconds.
Feeding trials were conducted for 20 d intervals. During trials, fish were fed 7.1% of body weight at 0500 h. An acoustic conditioning tone was played prior to feeding in the experimental treatment tank. One half hour after the feed delivery, the sampling boxes were removed from the tanks and the amount of feed eaten was calculated for each group.
Linear regressions of daily consumption were conducted for comparisons between the experimental and control tanks.
C. Important Results or Findings
1. Optimal Feeding Frequency
Mean fish weight, SGR, CV, FCR, total consumed and BWCd-1 for experiments 1A, 1B, and 1C are shown in Table 2. Feeding frequency did not affect SGR (Figure 1) or FCR for all experiments. Total consumption and BWCd-1 were significantly influenced by feeding frequency (Table 2). There was a general trend in fish that were fed more often to consume a greater amount of feed over the course of the experiment and have similar FCRs as those fed less often.
2. Feed Anticipatory Activity
FAA was not detected under either of the photoperiod regimes for Atlantic halibut. During the non-feeding phase, no rhythmicity was detected prior to feeding or during the remainder of the day.
3. Acoustic Conditioning
Preliminary results over a 16-day period indicate successful conditioning with acoustic stimuli (See figure 2).
D. Anticipated Success in Meeting Project Objectives on Schedule
Testing is currently ongoing for the acoustic conditioning experiment. These experiments will be completed by May 2004.
E. Reports, manuscripts, and presentations resulting from the project
Schnaittacher, G., King, W. & D.L. Berlinsky. The effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus (in preparation for Aquaculture Research)
II. Tasks and Activities for Next Reporting period
A. Tasks for the next reporting period
Operant conditioning experiments will be completed.
B. Brief work plan to accomplish tasks
Experiments will be conducted to determine if the number of daily feedings, or feed size, influences feed consumption following delivery of the acoustic signal.
C. Anticipated concerns or difficulties
None.
III. Expenditures
Expenditures were in the range anticipated for the work accomplished to date.