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Hyperbaric fish trap operation and deployment in the deep sea
Deep-Sea Research,Vol. 26A, pp. 1405 to 1409 © Pergamon Press Ltd 1979. Printed in Great Britain
0011-7471/79/1201-1405 $02.00/0
INSTRUMENTS AND METHODS Hyperbaric fish trap operation and deployment in the deep sea C. F. PHLEGER*, R. R. MCCONNAUGHEY~f and P. CRILL~" (Received 29 January 1979; in revisedform 22 May 1979; accepted 30 July 1979) Abstract--The operation and deployment of a hyperbaric fish trap is described. The cylindrical aluminum trap has successfully caught a rattail (Coryphaenoides acrolepis) and a sablefish (Anoplopomafimbria) from 1200 and 750 m depth, respectively, and held them under pressure at 1400 psi. The trap is set so that a wriggling fish on the hook triggers a series of events including: release of the ballast, pulling the fish into the trap by a negator spring, and closing the door. The trap is lowered to the sea floor as a free vehicle with a safety line to a surface float. If the trap does not rise on schedule, it can be pulled to the surface from great depth without a winch by a method we describe. INTRODUCTION
A NUMBEROF different pressurized traps, or hyperbaric traps, have been built. BROWN (1975) built a pressure fish trap of PVC (polyvinyl chloride) to catch benthopelagic fishes and hold them in deep water at 6 atm pressure. A live rattail was caught in this trap from 1200 m in the San Diego Trough. A number of pressure-retaining devices were described by BRAUER(1972). MACDONALDand GILCHRIST(1969, 1972) recovered samples of plankton in a pressure-retaining device from depths of 600m. More recently YAYANOS (1978) recovered and maintained live amphipods in a windowed pressure-retaining trap from 5700 m in the central North Pacific Ocean and kept them alive for nine days. YAYANOS (1978) also trapped amphipods at 10,500 m in the Marianas Trench in his well-designed and effective titanium trap (YAYANOS, 1977). JANNASCH, WIRSENand WINGET(1973) used a device that collects a sample of water and returns it under pressure to the sea surface for the study of microorganisms. In this report we describe an aluminum hyperbaric fish trap that has been used to catch benthopelagic rattails (Coryphaenoides acrolepis) and sablefish (Anoplopomafimbria) and to hold them under pressures of 1400 psi. We also describe a recovery technique we have used to retrieve the trap from 1200 m in the San Diego Trough without a winch or large ship. Our purpose in building and deploying the trap was to study biological membrane structure and function in the oxygen-filled swimbladder of an abyssal fish (PHLEGER and BENSON, 1971 ; PHLEGERand HOLTZ, 1973 ; JOSEPHSON,HOLTZ,MISOCKand PHLEGER,1975). DESCRIPTION AND OPERATION OF THE HYPERBARIC TRAP
The major parts of the trap include an upper aluminum tube (1.20 m long) attached to a lower tube of larger diameter (36.25 cm long). The larger tube houses the door and allows it * Department of Natural Science, San Diego State University, San Diego, CA 92182, U.S.A. t Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, U.S.A.
1405
1406
C.F. PHLEGER,R. R. McCONNAUGHEYand P. CRILL
to close from the inside (Fig. 1). The 5-cm thick aluminum plate is welded to the larger bottom tube. To increase strength, the end plate is seated 2.5 cm out from the large tube and attached by a 45 ° angle weld. The opening to the trap (14 cm dia) is offset to allow hinging of the closing door on one side. It is also designed to allow entry of the maximum head diameter of rattail fishes we know to have been collected off southern California. Shock cords are attached by eyebolts to the door and the outside of the thick aluminum end plate. These close the door when the pin, locking the door open, is pulled away by the negator spring as a fish is tugged into the trap. The door seats by means of an " O " ring and is held shut by pressure inside the trap as well as by the shock cords. The large bottom tube can be removed by hand or strap wrench from the main tube if necessary for repair. At the top end of the upper tube there is a removable end plate with a thick plexiglass window through which the fish can be viewed. Viewing is facilitated by a strong medical penlight and a chemiluminescent light ("cyalum") mounted inside the trap. Chemiluminescent lights work well at either 14.7 or 1400 psi, according to our tests in the hyperbaric trap itself and in ZoBell-Oppenheimer pressure cylinders. Fish mucous and excretory products may cloud the water and make viewing difficult. The narrow end plate also includes a valve for attachment of a gas accumulator (not shown in Fig. 1) and fittings for pressure gauges. The negator spring, used to pull the fish into the trap and shut the door, is model ML2921 (Ametek/Hunter Spring) and is a negator B motor. It is mounted on an aluminum plate (18.10 × 6.25 cm) mounted on two PVC tubes that fit the inside of the main tube. Each PVC tube is tightened to the main tube by three screws and can be removed easily for replacement of the negator spring. The trap is rigged so that when a fish is caught on the hook the leader is pulled out of a hole in the end plate, releasing two loops [Fig. 1). One loop (seven-strand stainless-steel wire coated with polyethylene) is pulled back by a spring, and a pair of large pliers then opens and releases the ballast and attached bait line on the bottom. The trap then starts to ascend lifted by the floats (Fig. 2). The other loop (monofiliment; 100 lb test), now released, pulls the hooked fish inside the trap. After the fish is completely inside the trap, the pin is pulled out of a hole (through a stationary aluminum block attached by welding an aluminum plate to the inside of the bottom tube) and the door closes from the inside. We are currently designing a gas accumulator to be activated after closing. Thermal expansion of the aluminum above the thermocline causes the trap to lose pressure, and this can be compensated for by an attached small compressed air cylinder acting as a gas accumulator, which releases air at a pressure of 1400 psi. The trap is made attractive to fish by two principal methods. First, a 12-m line between the trap and the ballast has about 20 pieces of string (0.5 m long) clamped to it with squid tied to the end of each string. This acts as a vertical set line to lure fish up to the trap from the sea floor. The only hook (also baited with squid) available is the hook attached to the trap. Therefore, specimens can only be caught on the trap hook itself. This may be of importance if there are only a few fish in a given area. It also increases the probability of catching a fish in the trap. Before using the hookless baited string technique, we caught rattails on the line below the trap but not in the trap itself. The second way the trap is made appealing to a fish is by light. A chemiluminescent light is taped onto the trap near the entrance prior to deploying the trap in the ocean. Two lines of evidence attest to the possible importance of light as a lure; (1) we never caught a fish in the trap prior to using the light, despite numerous attempts, and (2) we caught a large sablefish (Anoplopoma
Hyperbaric fish trap operation and deployment in the deep sea
~Pressure ~eugee
view fish
HsnJhng bracketbloses obqr after /z/ggina F/~h .
Sprm~.
relee~e~ bolle~t)
L ~ne I~ bs)fed ¢tr/.ngs end balle~r waists
I i ^ Fish -line befuJeen
neggfor 5p,rln~ enEt ~sh noo~
.Line ~ pin
5hock cords ~o close door
iH.:~
•leu? a/ire/~qser/ed2n ~ a / / hate in e n d plote "S a i / a d b o o k
Fig. 1. Cross section of aluminum hyperbaric fish trap.
1407
1408
C . F . PHLEGER, R. R. McCONNAUGHEYand P. CRILL
fimbria) in
the trap as the trap was descending but still 450 m above the bottom of the San Diego Trough (depth, 1200 m). This triggered the trap to release its ballast and rise prematurely. It was possible to tell the sablefish was caught 450 m above the bottom because the safety line (Fig. 2) was paying out rapidly from a tub and suddenly grew slack at 750 m. We then were able to recoil the line and the trap soon appeared at the surface. The chemiluminescent light may have been responsible for attracting the sablefish, which was swimming well above the bottom. We envision using fiberoptics to direct a small pinpoint of light to a position at the base of the fishhook and thus make the bait more attractive. The trap can be used at abyssal depths because it is equipped with a pressure-release valve. This insures that the relative pressure in the trap will never exceed the upper limit we have established in the laboratory for the trap (2250 psi). This is a working upper limit, not a bursting strength. Fish from abyssal depths with swimbladders should not be destroyed if they are held at 1400 psi. DEPLOYMENT AND RECOVERY OF THE TRAP
The trap, which weighs 77 kg in air and 55 kg in water, is deployed as a free vehicle and SOUTAR, 1971). We use 61 kg of flotation (as Coming glass spheres) attached to a cable on a bracket welded to the trap. The ballast weight (68-72 kg) is attached to the trap by a 12-m line (1/4" polypropylene) on which are clamped about 20 baited strings. A double magnesium release is situated between the weight and the 12-m line (Fig. 2). The double magnesium release acts as a backup release in case a fish does not trigger the trap and drop the weights. Releases of this type were described in PHLEGERand SOUTAR(1971). Care must be taken in deploying the trap from a ship to avoid premature triggering of the trap by hitting the side of the ship and breaking of the magnesium releases. The trap should not be deployed in heavy seas. Both the trap and attached floats must be lowered into the water from a winch and A-frame, or davits equipped with block and tackle rigs. The ballast is then lowered carefully through cleats by hand, and the baited strings are snapped on as the line enters the sea. Care must be taken not to jerk the magnesium release or the trap release as the ballast is lowered into the water. Finally, the system is released to descend to the sea floor. As the trap descends, a safety line to the surface (1/4" polypropylene) follows it attached to a shackle on the bridle above the floats. This safety line is important as the trap is not expendable and glass floats occasionally implode at depth. After the safety line has paid out and the trap is on the ocean floor, the safety line can be attached to a float, which drifts free of the ship. When the trap ascends a flag and radio signal that it is on the surface. The line is coiled into a line tub until the trap is encountered. The trap is then hauled on deck and placed in a cradle for pressure testing and examination of its contents through the window. If the trap does not ascend when expected, which may occur if a glass float implodes, it can be pulled from depth without a winch (Fig. 2). It is not advisable to operate the trap from a winch and cable because it is then subject to ship drift, which may be extensive. Also, greasy cables may not be attractive to fish, and there may be some vertical motion in heavy seas. The equipment needed for this recovery method includes (1) skiff plus outboard motor (one horsepower per pound of weight lifted should be a safe work load for outboards), (2) a float with at least twice the flotation of the weight to be lifted, (3) a small (PHLEGER
BOAT PULLIN6
Fig. 2.
F~ ~ - ~
(I)
~IOE VIEW DY SNATCH IN ~IlORKING POSITION
COILI#6 LINE ~, ~ 8LOeg /¢OZ~CN6 WE/6h'r
BLOCK ALINNII/~ FREE ~
A method for pulling a heavy weight from great depth without a winch.
dAM CLEAT/3NRTCH 61.~K
~
Hyperbaric fish trap operation and deployment in the deep sea
1409
parachute, 3 m dia (for weights of less than 50 kg), (4) a snatch block rigged with a jam cleat and open-top chocks (Fig. 2), and (5) a line longer than the depth to be worked with no knots or splices that will hang up in the block. The line must be longer than the depth because it is attached to the trap and follows it to the bottom. The other end of the line goes through the snatch block and jam cleat and is coiled in a tub and attached to a float. Although a jam cleat is a standard sailboat fitting, a snatch block attachment as we describe here is not, so far as we know. If necessary, this technique can be used from a ship. We have used a 200-1. oil drum and smaller fiberglass spheres for floats. A rubber life raft may be tied to the float to hold the line tubs. The technique is as shown in Fig. 2. The snatch block and jam cleat are essential to the operation if the line is to be pulled up and held fast as it is coiled. When the trap is visible below the float, it can be hauled up the remainder of the way by other equipment if available. This technique is useful for hauling equipment from great depths, because it requires no more than horizontal skiff (or ship) motion at the surface to haul the weight up vertically. It insures against loss of equipment and requires no winch. We used the technique once to haul the hyperbaric trap up from 1200 m depth when three glass floats imploded; it worked remarkably well. Acknowledgements--This work was supported by NSF grant BMS 75-07850 and a faculty research award from the San Diego State University Foundation. We thank A. SOUTAR and E. DUFFR~ for invaluable help in the
original design and constructing the hyperbaric trap. Ship time was generously provided by O. HOLM-HANSEN, K. SMITH, A. A. YAVANOS, C. Huaas, J. MATrIEWSONand C. Cox. Help at sea was provided by P. W. GRIMES, B. KELLER, B. BVrttqE, A. PESELY, and R. McCLINTOCK. Part of this research was completed while the senior author was on sabbatical leave in the laboratory of A. A YAVANOSat Scripps Institution of Oceanography. REFERENCES BgAUER R. W., editors (1972) Barobiology and the experimentalbiology of the deep sea, North Carolina Sea Grant Program, University of North Carolina, Chapel Hill, 428 pp. BROWN D. M. (1975) Four biological sample: opening-closing midwater trawl, closing vertical tow net, pressure fish trap, free vehicle drop camera. Deep-Sea Research, 22, 565-567. JANNASCH H. W., C. O. WmSEN and C. L. WINGET (1973) A bacteriological pressure-retaining deep sea sampler and culture vessel. Deep-Sea Research, 20, 661. JOSEPUSON R. V., R. B. HOLTZ, J. P.. MIsocK and C. F. PHLEGER (1975) Composition and partial protein characterization of swimbladder foam from deep-sea fish Coryphaenoides acrolepis and Antimora rostrata. Comparative Biochemistry and Physiology, 52B, 91-95. MACDONALDA. G. and I. GILCHRIST(1969) Recovery of deep seawater at constant temperature. Nature, London, 222, 71. MACDONALD A. G. and I. GILCHRIST (1972) An apparatus for the recovery and study of deep sea plankton at constant temperature and pressure. In: Barobiology and the experimental biology of the deep sea, R. W. BRAUER, editor, North Carolina Sea Grant Program, Chapel Hill, NC, pp. 394-407. PHLEGER C. F. and A. A. BENSON (1971) Cholesterol and hyperbaric oxygen in swimbladders of deep sea fishes. Nature, 230, 122. PHLEGER C. F. and R. B. HOLTZ (1973) The membranous lining of the swimbladder in deep sea fishes--I. Morphology and chemical composition. Comparative Biochemistry and Physiology, 45B, 867-873. PHLEGER C. F. and A. SOtrTAR (1971) Free vehicles and deep sea biology. American Zoologist, 11, 409-418. YAYANOS A. A. (1977) Simply actuated closure for a pressure vessel: Design for use to trap deep-sea animals. Review of Scientific Instruments, 48, 786-789. YAVANOS A. A. (1978) Recovery and maintenance of live amphipods at a pressure of 580 bars from an ocean depth of 5700 meters. Science, 200, 1056-1059.
0011-7471/79/1201-1405 $02.00/0
INSTRUMENTS AND METHODS Hyperbaric fish trap operation and deployment in the deep sea C. F. PHLEGER*, R. R. MCCONNAUGHEY~f and P. CRILL~" (Received 29 January 1979; in revisedform 22 May 1979; accepted 30 July 1979) Abstract--The operation and deployment of a hyperbaric fish trap is described. The cylindrical aluminum trap has successfully caught a rattail (Coryphaenoides acrolepis) and a sablefish (Anoplopomafimbria) from 1200 and 750 m depth, respectively, and held them under pressure at 1400 psi. The trap is set so that a wriggling fish on the hook triggers a series of events including: release of the ballast, pulling the fish into the trap by a negator spring, and closing the door. The trap is lowered to the sea floor as a free vehicle with a safety line to a surface float. If the trap does not rise on schedule, it can be pulled to the surface from great depth without a winch by a method we describe. INTRODUCTION
A NUMBEROF different pressurized traps, or hyperbaric traps, have been built. BROWN (1975) built a pressure fish trap of PVC (polyvinyl chloride) to catch benthopelagic fishes and hold them in deep water at 6 atm pressure. A live rattail was caught in this trap from 1200 m in the San Diego Trough. A number of pressure-retaining devices were described by BRAUER(1972). MACDONALDand GILCHRIST(1969, 1972) recovered samples of plankton in a pressure-retaining device from depths of 600m. More recently YAYANOS (1978) recovered and maintained live amphipods in a windowed pressure-retaining trap from 5700 m in the central North Pacific Ocean and kept them alive for nine days. YAYANOS (1978) also trapped amphipods at 10,500 m in the Marianas Trench in his well-designed and effective titanium trap (YAYANOS, 1977). JANNASCH, WIRSENand WINGET(1973) used a device that collects a sample of water and returns it under pressure to the sea surface for the study of microorganisms. In this report we describe an aluminum hyperbaric fish trap that has been used to catch benthopelagic rattails (Coryphaenoides acrolepis) and sablefish (Anoplopomafimbria) and to hold them under pressures of 1400 psi. We also describe a recovery technique we have used to retrieve the trap from 1200 m in the San Diego Trough without a winch or large ship. Our purpose in building and deploying the trap was to study biological membrane structure and function in the oxygen-filled swimbladder of an abyssal fish (PHLEGER and BENSON, 1971 ; PHLEGERand HOLTZ, 1973 ; JOSEPHSON,HOLTZ,MISOCKand PHLEGER,1975). DESCRIPTION AND OPERATION OF THE HYPERBARIC TRAP
The major parts of the trap include an upper aluminum tube (1.20 m long) attached to a lower tube of larger diameter (36.25 cm long). The larger tube houses the door and allows it * Department of Natural Science, San Diego State University, San Diego, CA 92182, U.S.A. t Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, U.S.A.
1405
1406
C.F. PHLEGER,R. R. McCONNAUGHEYand P. CRILL
to close from the inside (Fig. 1). The 5-cm thick aluminum plate is welded to the larger bottom tube. To increase strength, the end plate is seated 2.5 cm out from the large tube and attached by a 45 ° angle weld. The opening to the trap (14 cm dia) is offset to allow hinging of the closing door on one side. It is also designed to allow entry of the maximum head diameter of rattail fishes we know to have been collected off southern California. Shock cords are attached by eyebolts to the door and the outside of the thick aluminum end plate. These close the door when the pin, locking the door open, is pulled away by the negator spring as a fish is tugged into the trap. The door seats by means of an " O " ring and is held shut by pressure inside the trap as well as by the shock cords. The large bottom tube can be removed by hand or strap wrench from the main tube if necessary for repair. At the top end of the upper tube there is a removable end plate with a thick plexiglass window through which the fish can be viewed. Viewing is facilitated by a strong medical penlight and a chemiluminescent light ("cyalum") mounted inside the trap. Chemiluminescent lights work well at either 14.7 or 1400 psi, according to our tests in the hyperbaric trap itself and in ZoBell-Oppenheimer pressure cylinders. Fish mucous and excretory products may cloud the water and make viewing difficult. The narrow end plate also includes a valve for attachment of a gas accumulator (not shown in Fig. 1) and fittings for pressure gauges. The negator spring, used to pull the fish into the trap and shut the door, is model ML2921 (Ametek/Hunter Spring) and is a negator B motor. It is mounted on an aluminum plate (18.10 × 6.25 cm) mounted on two PVC tubes that fit the inside of the main tube. Each PVC tube is tightened to the main tube by three screws and can be removed easily for replacement of the negator spring. The trap is rigged so that when a fish is caught on the hook the leader is pulled out of a hole in the end plate, releasing two loops [Fig. 1). One loop (seven-strand stainless-steel wire coated with polyethylene) is pulled back by a spring, and a pair of large pliers then opens and releases the ballast and attached bait line on the bottom. The trap then starts to ascend lifted by the floats (Fig. 2). The other loop (monofiliment; 100 lb test), now released, pulls the hooked fish inside the trap. After the fish is completely inside the trap, the pin is pulled out of a hole (through a stationary aluminum block attached by welding an aluminum plate to the inside of the bottom tube) and the door closes from the inside. We are currently designing a gas accumulator to be activated after closing. Thermal expansion of the aluminum above the thermocline causes the trap to lose pressure, and this can be compensated for by an attached small compressed air cylinder acting as a gas accumulator, which releases air at a pressure of 1400 psi. The trap is made attractive to fish by two principal methods. First, a 12-m line between the trap and the ballast has about 20 pieces of string (0.5 m long) clamped to it with squid tied to the end of each string. This acts as a vertical set line to lure fish up to the trap from the sea floor. The only hook (also baited with squid) available is the hook attached to the trap. Therefore, specimens can only be caught on the trap hook itself. This may be of importance if there are only a few fish in a given area. It also increases the probability of catching a fish in the trap. Before using the hookless baited string technique, we caught rattails on the line below the trap but not in the trap itself. The second way the trap is made appealing to a fish is by light. A chemiluminescent light is taped onto the trap near the entrance prior to deploying the trap in the ocean. Two lines of evidence attest to the possible importance of light as a lure; (1) we never caught a fish in the trap prior to using the light, despite numerous attempts, and (2) we caught a large sablefish (Anoplopoma
Hyperbaric fish trap operation and deployment in the deep sea
~Pressure ~eugee
view fish
HsnJhng bracketbloses obqr after /z/ggina F/~h .
Sprm~.
relee~e~ bolle~t)
L ~ne I~ bs)fed ¢tr/.ngs end balle~r waists
I i ^ Fish -line befuJeen
neggfor 5p,rln~ enEt ~sh noo~
.Line ~ pin
5hock cords ~o close door
iH.:~
•leu? a/ire/~qser/ed2n ~ a / / hate in e n d plote "S a i / a d b o o k
Fig. 1. Cross section of aluminum hyperbaric fish trap.
1407
1408
C . F . PHLEGER, R. R. McCONNAUGHEYand P. CRILL
fimbria) in
the trap as the trap was descending but still 450 m above the bottom of the San Diego Trough (depth, 1200 m). This triggered the trap to release its ballast and rise prematurely. It was possible to tell the sablefish was caught 450 m above the bottom because the safety line (Fig. 2) was paying out rapidly from a tub and suddenly grew slack at 750 m. We then were able to recoil the line and the trap soon appeared at the surface. The chemiluminescent light may have been responsible for attracting the sablefish, which was swimming well above the bottom. We envision using fiberoptics to direct a small pinpoint of light to a position at the base of the fishhook and thus make the bait more attractive. The trap can be used at abyssal depths because it is equipped with a pressure-release valve. This insures that the relative pressure in the trap will never exceed the upper limit we have established in the laboratory for the trap (2250 psi). This is a working upper limit, not a bursting strength. Fish from abyssal depths with swimbladders should not be destroyed if they are held at 1400 psi. DEPLOYMENT AND RECOVERY OF THE TRAP
The trap, which weighs 77 kg in air and 55 kg in water, is deployed as a free vehicle and SOUTAR, 1971). We use 61 kg of flotation (as Coming glass spheres) attached to a cable on a bracket welded to the trap. The ballast weight (68-72 kg) is attached to the trap by a 12-m line (1/4" polypropylene) on which are clamped about 20 baited strings. A double magnesium release is situated between the weight and the 12-m line (Fig. 2). The double magnesium release acts as a backup release in case a fish does not trigger the trap and drop the weights. Releases of this type were described in PHLEGERand SOUTAR(1971). Care must be taken in deploying the trap from a ship to avoid premature triggering of the trap by hitting the side of the ship and breaking of the magnesium releases. The trap should not be deployed in heavy seas. Both the trap and attached floats must be lowered into the water from a winch and A-frame, or davits equipped with block and tackle rigs. The ballast is then lowered carefully through cleats by hand, and the baited strings are snapped on as the line enters the sea. Care must be taken not to jerk the magnesium release or the trap release as the ballast is lowered into the water. Finally, the system is released to descend to the sea floor. As the trap descends, a safety line to the surface (1/4" polypropylene) follows it attached to a shackle on the bridle above the floats. This safety line is important as the trap is not expendable and glass floats occasionally implode at depth. After the safety line has paid out and the trap is on the ocean floor, the safety line can be attached to a float, which drifts free of the ship. When the trap ascends a flag and radio signal that it is on the surface. The line is coiled into a line tub until the trap is encountered. The trap is then hauled on deck and placed in a cradle for pressure testing and examination of its contents through the window. If the trap does not ascend when expected, which may occur if a glass float implodes, it can be pulled from depth without a winch (Fig. 2). It is not advisable to operate the trap from a winch and cable because it is then subject to ship drift, which may be extensive. Also, greasy cables may not be attractive to fish, and there may be some vertical motion in heavy seas. The equipment needed for this recovery method includes (1) skiff plus outboard motor (one horsepower per pound of weight lifted should be a safe work load for outboards), (2) a float with at least twice the flotation of the weight to be lifted, (3) a small (PHLEGER
BOAT PULLIN6
Fig. 2.
F~ ~ - ~
(I)
~IOE VIEW DY SNATCH IN ~IlORKING POSITION
COILI#6 LINE ~, ~ 8LOeg /¢OZ~CN6 WE/6h'r
BLOCK ALINNII/~ FREE ~
A method for pulling a heavy weight from great depth without a winch.
dAM CLEAT/3NRTCH 61.~K
~
Hyperbaric fish trap operation and deployment in the deep sea
1409
parachute, 3 m dia (for weights of less than 50 kg), (4) a snatch block rigged with a jam cleat and open-top chocks (Fig. 2), and (5) a line longer than the depth to be worked with no knots or splices that will hang up in the block. The line must be longer than the depth because it is attached to the trap and follows it to the bottom. The other end of the line goes through the snatch block and jam cleat and is coiled in a tub and attached to a float. Although a jam cleat is a standard sailboat fitting, a snatch block attachment as we describe here is not, so far as we know. If necessary, this technique can be used from a ship. We have used a 200-1. oil drum and smaller fiberglass spheres for floats. A rubber life raft may be tied to the float to hold the line tubs. The technique is as shown in Fig. 2. The snatch block and jam cleat are essential to the operation if the line is to be pulled up and held fast as it is coiled. When the trap is visible below the float, it can be hauled up the remainder of the way by other equipment if available. This technique is useful for hauling equipment from great depths, because it requires no more than horizontal skiff (or ship) motion at the surface to haul the weight up vertically. It insures against loss of equipment and requires no winch. We used the technique once to haul the hyperbaric trap up from 1200 m depth when three glass floats imploded; it worked remarkably well. Acknowledgements--This work was supported by NSF grant BMS 75-07850 and a faculty research award from the San Diego State University Foundation. We thank A. SOUTAR and E. DUFFR~ for invaluable help in the
original design and constructing the hyperbaric trap. Ship time was generously provided by O. HOLM-HANSEN, K. SMITH, A. A. YAVANOS, C. Huaas, J. MATrIEWSONand C. Cox. Help at sea was provided by P. W. GRIMES, B. KELLER, B. BVrttqE, A. PESELY, and R. McCLINTOCK. Part of this research was completed while the senior author was on sabbatical leave in the laboratory of A. A YAVANOSat Scripps Institution of Oceanography. REFERENCES BgAUER R. W., editors (1972) Barobiology and the experimentalbiology of the deep sea, North Carolina Sea Grant Program, University of North Carolina, Chapel Hill, 428 pp. BROWN D. M. (1975) Four biological sample: opening-closing midwater trawl, closing vertical tow net, pressure fish trap, free vehicle drop camera. Deep-Sea Research, 22, 565-567. JANNASCH H. W., C. O. WmSEN and C. L. WINGET (1973) A bacteriological pressure-retaining deep sea sampler and culture vessel. Deep-Sea Research, 20, 661. JOSEPUSON R. V., R. B. HOLTZ, J. P.. MIsocK and C. F. PHLEGER (1975) Composition and partial protein characterization of swimbladder foam from deep-sea fish Coryphaenoides acrolepis and Antimora rostrata. Comparative Biochemistry and Physiology, 52B, 91-95. MACDONALDA. G. and I. GILCHRIST(1969) Recovery of deep seawater at constant temperature. Nature, London, 222, 71. MACDONALD A. G. and I. GILCHRIST (1972) An apparatus for the recovery and study of deep sea plankton at constant temperature and pressure. In: Barobiology and the experimental biology of the deep sea, R. W. BRAUER, editor, North Carolina Sea Grant Program, Chapel Hill, NC, pp. 394-407. PHLEGER C. F. and A. A. BENSON (1971) Cholesterol and hyperbaric oxygen in swimbladders of deep sea fishes. Nature, 230, 122. PHLEGER C. F. and R. B. HOLTZ (1973) The membranous lining of the swimbladder in deep sea fishes--I. Morphology and chemical composition. Comparative Biochemistry and Physiology, 45B, 867-873. PHLEGER C. F. and A. SOtrTAR (1971) Free vehicles and deep sea biology. American Zoologist, 11, 409-418. YAYANOS A. A. (1977) Simply actuated closure for a pressure vessel: Design for use to trap deep-sea animals. Review of Scientific Instruments, 48, 786-789. YAVANOS A. A. (1978) Recovery and maintenance of live amphipods at a pressure of 580 bars from an ocean depth of 5700 meters. Science, 200, 1056-1059.