FISHERIES RESEARCH BOARD OF CANADA
TECHNICAL REPORT NO.283
1971
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FISHERIES RESEARCH BOARD OF CANADA
Technical Reports
FRS Technical Reports are research documents that are of sufficient
importance to be preserved, but which "Cor some reason are not appropriate for
primary scientific publication. No restriction is placed on subject matter and the
series should reflect the broad research interests of FRS.
These Reports can be cited in publications, but care should be taken
to indicate their manuscript status. Some of the material in these Reports will
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Inquiries concerning any particular Report should be directed to the
issuing FRB establishment which is indicated on the title page.
FISHERIES RESEARCH BOARD OF CANADA
TECHNICAL REPORT NO. 2B3
AN ENVIRONMEm'AL-CONTROL TANK FOR THE SYNCHRONOUS stUDY OF
GRGlTH AND METABOLISM OF YOUNG SAU10N
By
J. R. Brett, D. B. Sutherland and G. D. Heritage
FISHERIES RESEARCH BOARD OF CANADA
Biological Station, Nana1mo, B. C.
NOVEMBER 1971
- 1 -
ABSTRACT
A 40-ga1100 fiberglas tank with suitable temperature, oxygen and flow
controls is described for use in determining energy budgets of small fish.
INTRODUCTION
A small holding tank, useful in the culture, special care and accli·
mation of young salmon in the laboratory was described by Alderdice et al.
(1966). With only slight modifications, involving the addition of a recircu-
lating pump, i t has been used extensively in experiments on factors affecting
rate of growth (Brett et al., 1969), and in studies on rate of digestion and
food intake (Brett and Higgs, 1970; Brett, 1971).
Early in 1969 i t was decided to adapt this tank for studies on energy
budgets, involving the synchronous measurement of rates of food intake, growth,
metabolism and excretion. To this end the normal plexiglas top was temporarily
cemented to the fiberglas tank and the central hole in the lid used to insert
a rubber cork in the overflow drain. This enabled filling the tank to the
flooding point, turning off the incoming water, and measuring the oxygen depletion in the closed-circuit recirculating system (for metabolic rate determinations). Despite implementing a series of modifications the equipment was
fraught with a variety of deficiencies which included small air bubbles trapped
under the lid, indeterminable slight leaks between the flooded lid and the
internal recirculated water, induced excitement of the fish when switching
from open to closed circuit, drifts in temperature from heat-input of the pump
when on closed circuit, and difficulty in meeting the provision that oxygen
should not be depleted by more than 20 ± 5% in anyone of the multi-combinations of temperature Bnd food ration prescribed. 1 Consequently it was decided
to redesign the whole system incorporating all the ideas which had been gained
from the preliminary efforts, including applying knowledge obtained from the
design and operation of respirometers (Ma r, 1959; Brett, 1964).
DESIGN FEATURES
For simplicity of presentation it is convenient to divide the apparatus, which is illustrated in Fig. 1-4, into three connecting and interrelated
systems:
1) Input and preparation of water
Primary control of water temperature is achieved by cross-mixing
heated and chilled freshwater supply lines, using manually controlled PVC
lA report on these preliminary experiments was presented at the annual
meeting of the Canadian Cormnittee on Freshwater Fisheries Research, Montreal,
January, 1971.
- 2 -
diaphragm valves. An accuracy of + O.SoC is only required at this stage.
Flow is adjusted to flush the tank-at a rate of two volume-exchanges per hour
(approx. 80 gph for a 40-ga1 tank). On occasion the water may be significantly
above or below normal air-saturation. Where high-presBure water lines are involved supersaturation at the lethal level (over llot with N.;) may occur,
either at normal temperatures or, in particular, in heated lines. Incoming
water is therefore passed through a stripping column, cascading over ceramic
saddles in counter-current with a rising air flow.
The conditioned water passes thence into a bubble trap, the tubular
outlet of which inserts through the tank lid, discharging below the water
level of the tank. A slight constriction of this tube causes the trap to
fill just to the overflow point, assuring bubble·free input. Since the
bubble trap is attached to the removable lid, flexible tubing is used for
both the short lengths of tube leading inrnediately into and overflowing out
of the trap (detachable). When closed circuit is required a flow control
valve on the line leading to the trap is turned off; the backed-up water in
the stripping column rises to an overflow line, by-passing the tank to waste.
No further adjustment is required; reintroduction of conditioned water may
be had without any manipulation beyond simply opening this valve again.
2} Fish tank with flushing and/or recirculating water
The fish tank is essentially the same as the earlier culture tank
in most of its features (cf., Alderdice et al., 1966). Incoming water is
swept into circulation, produced by the recirculation pump, at some prescribed
mean velocity (max. of 1.2 ft/sec), and overflows to waste from a central
pipe. An outer, encasing drain pipe of clear plexiglas, higher than the overflow pipe, forces flushed water to pass through bottom slots, carrying fecal
matter or unused food rapidly to waste.
Recirculated water, on an independent circuit, 1s drawn through a
rosette of fine holes drilled in the wall and pumped to an imbedded, perforated pipe. The perforation holes jet water in a vertical "fan" along the
opposite side of the tank creating fairly smooth water-currents swirling
around the tank. The force of the jets is throttled by a valve, in series
with a pressure gauge.
To switch onto closed circuit an off-set pressure clamp is first
actuated, pinching off a short rubber sleeve at the drain. Water rises to
flood the tank, impinging on the under surface of the plexiglas top. This
latter has been sealed by inserting jam locks around the periphery, compressing the O-ring contact surface (see insert, Fig. I). Since the tank is
tilted slightly down at the back or wall end, the rising water displaces all
air forward along a creeping water-front, and through corner holes in the
front edge of the cover. Once the tank is filled to overflowing the flow
control valve is turned off leaVing the water in the bubble trap to seek a
lower level in equilibrium with the flooded top. Corks are then inserted in
the small flood holes and in the feeding funnel. A water sample is inmediately
- 3 -
taken for oxygen determination, from the small valve below the tank (tapped
into the case of the heat-exchanger).
3) Recirculating. sensing. controlling
On a platform below the tank are mounted the basic parts for circulating, sensing and controlling the tank water system. An impeller pump
with neoprene head recirculates the water through a heat exchanger, past a
pressure gauge, over temperature and oxygen sensors, and thence into the jet
pipe. The heat-exchanger incorporates an aluminum coil through which chilled
water is continually passed at a rate which just overcomes all heat input.
A 300-watt heater with thermister sensor is activated by a proportional thermoregulator for precise temperature control (± a.IOC), independent of open or
closed circuit.
To keep track of the temperature stability, over weeks of continuous
operation, a thermograph bulb is housed in a small sensor chamber (see insert,
Fig. 1). This chamber also houses the oxygen probe and coupled thermister,
for continuous monitoring of oxygen saturation level.
A time switch is used to control photoperiod for a set of tanks in
a light-sealed room.
PRACTICE
In practice, fish are temperature-acclimated °in the tanks for 1 month
prior to commencing an experiment. During this period ration control is
applied. The following 6 weeks are devoted to weekly weighings, including
2 weeks (usually 3rd and 5th) for metabolic rate determinations. The latter
are conducted on a continuous 24-hour program in which each tank is cycled
on a regular open-/closed-circuit program -- equal ~ and off periods of either
2, 3 J or 4 hours depending on the time necessary to draw down the 20 ± 51. of
the oxygen content. The period is set by checking from the 0a-probe readings.
To minimize disturbance a "blind"a is used to cover access to the
feeding funnel of each tank (some fish are fed twice a day; others as little
as once every third day). The tank height at lid level is approximately
5 feet. Water level in the tank is adjusted to be about 1/4 inch below the
lid so that the closed circuit causes only a slight level change. One darkred light and one white light hang over each tank; only the white is on the
time-switch.
The energy lost to excretion can be determined "by difference," in
the simple relation: Food input"'" Growth + Metabolism + Excretion. To date
aIn some cases it has been found desirable to use a small "fish-eye"
peep in the blind.
- 4 -
separate experiments have been conducted for direct measurement of excretion,
trapping feces at the tank drain in a fine-meshed screen, and sampling the
water regularly for ammonia and urea content. The methodology is still under
development; there do not appear to be any serious obstacles to synchronous
measurement of all parameters.
In general the design and operation have met the earlier limitations
of air locks, slight lid leaks, temperature drifts, limited visibility of
food particles and feces, disturbance from switching systems, and general
inaccessibility of controls and monitoring equipment.
A materials list, 1971 costs, tank fabrication specifications, parts
list and working drawings are appended. The tank moulds were built through
a cooperative program with the Shipyard Department at H.M.C. Dockyard,
Esquimalt, B.C. They are the property of the Fisheries Research Board of
Canada, and may be had by special arrangement through the Director, Nanaimo
Biological Station, Nanaimo, B.C.
AC~LEDGMENrS
Mr. A. A. Denbigh expertly produced the 3-dimensional drawing (Fig. 1);
Mr. D. J. Redman provided the carefully drafted blueprints; and Mr. C. J. Morley
kindly photographed the apparatus (Fig. 2-4). It is a pleasure to express our
gratitude for their cooperative help.
REFERENCES
Alderdice, D.F., J.R. Brett, and D.B. Sutherland. 1966. Design of small
holding tank for fish. J. Fish. Res. Bd. Canada 23: 1447-1450.
Brett, J.R. 1964. The respiratory metabolism and swirmning performance of
young sockeye sallOOn. J. Fish. Res. Bd. Canada 21: 1183-1226.
1971. Satiation time, appetite and maximum food-intake of sockeye
salmon, Oncorhynchus nerka. J. Fish. Res. Bd. Canada 28: 409-415.
Brett, J.R., and D.A. Higgs. 1970. Effect of temperature on the rate of
gastric digestion in fingerling sockeye salmon, Oncorhynchus nerka.
J. Fish. Res. Bd. Canada 27: 1767-1779.
Brett, J.R., J.E. Shelbourn, and C.T. Shoop. 1969. Growth rate and body
composition of fingerling sockeye salmon, Oncorhynchus nerka, in relation
to temperature and ration size. J. Fish. Res. Bd. Canada 26: 2363-2394.
Mar, J. 1959. A proposed tunnel design for a fish respirometer. Tech.
Memo. 59-3, Pacific Naval Lab., D.R.B., Esquimalt, B.C. 13 p.
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Fig. 1. Schematic drawing of the environmental-control tank sho.... ing the path of water for open- and closedcircuit operation. Inserts display detail of the removable jam locks used to seal the plexiglas top,
and an adapted filter jar tapped to receive oxygen and temperature sensors. The assembly divides
naturally into three systems indicated in the margin to the right.
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Fig. 2. A row of six fully equipped tanks showing the front control
panel and readily accessible flow control valves. Insulated
polyethelene lines below the tanks carry chilling water to the
heat exchangers.
Fig. 3. Lines above the tank servicing the in-put water are shown. Incoming water passes through a flow·meter l
into the top of the stripping column (bottom shown), through the flow control valve, and into the bubble
trap. The labelled offset jam lock is in the open position (removable) with the others rotated to seal
the plexiglas top.
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Fig. 4. Platform below tank showing the recirculating, sensing and controlling system. The vertical pipe
carries water from the rosette of fine holes in the wall of the tank down past a shut-off valve to
the recirculation pump. The insulated line resting on top of the pump is a waste line for chilled
water. It was found useful to monitor this flow by a small meter shown.
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Appendix A.
Part
List of parts, suppliers, and 1971 costs.
Supplier
Cost
56.00
Fiberglas tank
Fiberglas Specialties,
Vancouver, B.C.
Oxygen probe and temperature compensator
Kent Cambridge, Willodale,
Thermograph
Taylor Instruments, Toronto
Ontario
548.00
Proportional controller
Cole Parmer Instruments,
Chicago, Illinois
125.00
182.00
Ontario
14.00
Thermister
20.00
Flow meters
Sherman Agencies, Vancouver, B.C.
Aluminum tube
Wilkinson Co., Vancouver, B.C.
15.00/100 ft
Offset jamlock
Naval Dockyards, Esquimalt, B.C.
Price not
available
Polyurethane insulation
Quartz heaters
Canlab, Vancouver, B.C.
Silicone sealant
Dow Corning, Vancouver, B.C.
Motor mounts
Lo-Rez Vibration Control,
Vancouver, B.C.
Ceramic saddles
U.S. Stoneware, Akron, Ohio
Air stone
Arbor Scientific, Port Credit,
Ontario
1/2" P.V.C. pipe
Grinnell Co. of Canada, Vancouver,
B.C.
16.00
3.65/12
.75
3D.OO/cu ft
.35
.20/ft
l.05/ft
2/1 P. V.C. pipe
23.86
Ball valves
3.13/ft
4 11 P.V.C. pipe
A.S.S. fitting
Crane Co., Nanaimo, B.C.
Eastern pump
Fleck Bros., Vancouver, B.C.
l. 76
200.00
53.10/100 ft
Armaflex insulation, 1/2"
.33/ft
Nylon tube
38.00
Sensor chamber
Peacock Bros., Vancouver, B.C.
Pressure off-set clamp
De-sta-Co Company, Detroit Stamping
Co., Detroit, Michigan
6.00
Johnston Industrial Plastics,
Vancouver, B.C.
3.57/ft
Plexiglas stand pipe
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