REMINISCENCES | Asherah, a two-man submarine named for a Phoenician goddess
This all started in 1959 when a twenty-six-year-old who was studying for his PhD in archaeology at the University of Pennsylvania was asked if he would like to direct the excavation of a Bronze Age ship that had been discovered in 90 feet of water off the coast of Turkey. His name was George Bass, and he said that he would direct the excavation after learning to scuba dive, and within a few years he would turn the world of underwater archaeology upside down.
At the conclusion of the excavation he decided there might be more efficient ways of locating other ancient wrecks and mapping their remains once found than by using scuba gear with its strict limitations on bottom time. He thought a small two-man submarine would allow archaeologists to locate wrecks down to 300 feet and more and to map them using aerial survey techniques rather than by hand measurements.
Tapping an experienced submarine builder
Although still finishing his doctoral studies, his enthusiasm had infected the administration of the University Museum so that in 1963, the museum approved his proposal to obtain a grant to acquire a small submarine. After a search for the proper builder, George chose the Electric Boat division of the General Dynamics Corporation and the company’s engineers and submarine builders completed construction of the little submarine, named Asherah after a Phoenician sea goddess. It was delivered in 1964 to the now Doctor George Bass and its new owner the University Museum. She was christened by George’s wife Ann on May 28, 1954.
Its cost was very modest: US$50,000 because Electric Boat’s Research and Development group absorbed the other half of its US$100,000 price. The reason it was built so quickly is because the Electric Boat division had lots of experience from building submarines for the US Navy. For a more detailed article on Dr. George Bass go to: Keiger, Dale. 1997 (April). The Underwater World of George Bass. Johns Hopkins Magazine (Another source is http://pages.jh.edu/jhumag/0497web/bass.html.).
Deployment to the Pacific
On June 17, 1965, Secretary of the Interior Stewart L. Udall announced that a study sponsored by the Bureau of Commercial Fisheries (now the National Marine Fisheries Service) shows that it is feasible to build a specially designed nuclear-powered submarine for fishery and oceanography research. The known behaviour and distribution of tuna indicated that such a submarine should have a 20-knot speed, a 1,000-foot operational depth, and a submerged endurance of six weeks.
With these criteria, Electric Boat made a preliminary design for a submarine that would be 163.5 feet long, have a submerged speed of 20 knots, a surface speed of 11 knots, and an operating depth of 1,000 feet. The craft would carry seven scientists in addition to a crew of 24. There would be an eight-foot observation sphere in the bow, multiple observation windows, and seven television cameras would be mounted on the hull. A tube would be placed in the stern laboratory, where plankton nets and trawl nets could be deployed. It would take about five years to build.
Unfortunately, this is as far as obtaining the submarine went. Various reasons were given but the most likely reason was that the money set aside to build the boat was diverted to the needs of the Vietnam War. This did not stop the Bureau of Commercial Fisheries from seeking experience with a submarine charged with exploring and developing the high seas fishery resources of the Pacific Ocean. Among the resources that received attention are several species of pelagic fish: tuna, billfishes, sharks, and others. Emphasis has been placed on skipjack tuna (aku), an abundant small tuna that was not yet fully exploited in 1964.
Recent advances in observing tuna from underwater viewing chambers on the bureau’s fishery research vessel Charles H. Gilbert just whetted the appetite of the laboratory to acquire more experience in observing tuna and bottom-dwelling organisms. The first submarine to be tested was Asherah, a two-man submarine that had just been delivered to its owner, the University of Pennsylvania Museum, but was chartered in 1965 by the Honolulu Laboratory from the Electric Boat division of General Dynamics Corporation.
Asherah operated in conjunction with a mothership, the research vessel Townsend Cromwell, for one month in the coastal waters of Oahu. Operational problems were minor, and Asherah completed 50 dives during the charter period. Dives were made by day and night with many to the submarine’s maximum operational depth of 600 feet. Missions included investigation of the plankton community, tuna and tuna forage, survey of the sea floor and its resources, measurements of currents while drifting, bioacoustics research, and various incidental studies.
While the charter was primarily undertaken to obtain submarine operating experience, there were several unexpected research dividends. Of greatest interest were observations in the vertical distribution on tuna and their forage and on the surprisingly extensive resources on the bottom. This included surprisingly large spiny lobsters, pen shells, red coral, and heart urchins.
When not diving, Asherah was moored to a boom from Townsend Cromwell. The divers came from the personnel of the Honolulu Laboratory and the following are the names of some whose names are known as this episode is being written in February 2019: Dr. Donald Strasburg, Dr. John Magnuson, Reginald Gooding, Heeny Yuen, Everet C. Jones, and Bob Iversen. I apologise to those divers who are not listed, as Asherah’s archive was not available to this writer.
Missions and results of specific research objectives
1. Describe the plankton community in relation to various physical features and its diurnal migrations.
Plankton was studied during portions of eight dives. Observations were by day and night, between the surface and maximum depth of 192 metres, and with and without lights. Lights did not attract plankters at great depths, and few plankters were seen around surface night lights. Plankton was generally abundant between 60 and 180 metres by day and was richer at greater depths. Swimming plankters were seen only at night, when the plankton tended to be layered, with concentrations at the surface. Small particles of white material, possibly the “marine snow” of other observers, were encountered in great quantities slowly settling to the bottom.
Particle diameter was estimated at about 0.2 mm, but sometimes was as great at one to two mm. Counts and spacing estimates of plankton, made by eye, indicated an average density of about 1,000 mg of plankton per cubic meter of water. This amount is about 50 times as much as is normally caught in net hauls in the open ocean around Oahu. The discrepancy between the value for observed and captured plankton indicates the extent of escapement or the loss of fragile plankters through the meshes of nets.
2. Determine the availability of tuna, tuna forage, and those species which are present but not eaten by tuna.
Skipjack tuna and little tuna (kawakawa) were encountered by Dr. John Magnuson on several dives at surprisingly great depths of 98 to 152 metres. The temperature at 152 metres as 17.8 degrees Celsius. Usually these tuna were in groups of three to six fish, but once they formed a school of 250 fish whose vertical dimension was 30 metres and another time three tuna were associated with 30 jacks. The school of 250 tuna seemed unafraid of the submarine and simply opened its ranks to allow the submarine to pass through vertically.
Tuna forage organisations were seen on 13 dives and consisted of four species of small fish, only one of which was identified. These fish occurred between 107 and 192 metres. Vast schools swam slowly along the face of a steep cliff. Tuna, amberjack and other fish preyed on them. Three specimens of squirrel fish were accidentally trapped in the free flooding sail of Asherah. One reached the surface alive and lived in an aquarium on Townsend Cromwell for two weeks. In the depth these fish bore the typical coloration of deep blue and silver. After a few hours’ confinement, however, the aquarium specimen developed the red and white stripes, by which it is well known on all shallow Hawaiian reefs.
Although commonly found in tuna and marlin stomachs, the fish had not been suspected to have a deep-water nursery ground. Three unidentified forage fishes were respectively guppy-like, serranid-like, and eleotrid-like. Their lengths were about 25 to 100 mm.
Many estimates of forage school size were made; they ranged from a few hundred fish to more than 10,000. One estimate was expressed in practical fishermen’s terms of “300 buckets of bait”, or an equivalent of 950 kg of small fish. The schools of forage fish were numerous and constituted a resource of millions of fish.
Two forage species exhibited peculiar behavior. Before dawn, 150 mm paralepidid fish hovered 10 to 20 cm above the sandy bottom at 40 to 100 metres. Similar paralepidids commonly occur around night-lights and have hitherto been regarded as pelagic rather than demersal. On the dive in which the paralepidids were seen by Reginald Gooding, a mixed school of 200 bigeye scad (akule), and mackerel scad (opelu) followed the submarine down from the surface. The submarine’s lights were on. When Asherah reached 110 metres, the mackerel scad inverted and began swimming in circles about 20 metres in diameter. The bigeye scad continued to swim normally.
On Asherah’s ascent, the mackerel scad continued their inverted swimming, but at 100 metres, the circle widened to a diameter of 30 to 60 cm. At 88 metres, normal swimming was resumed. The fish stayed with Asherah until it reached a depth of 30 metres.
3. Survey the bottom for fishery resources.
A bottom survey was the major purpose of 17 dives by Dr. Donald Strasburg and Heeny Yuen, and incidental bottom observations were made on 11 others. The survey covered a depth range of 24 to 192 metres. In the shallow (24 to 107 metres) inshore surveys, the bottom was a sloping sandy plain, interrupted by rocky ledges three to 18 metres high. The sandy stretches between the ledges were nearly featureless and were largely devoid of visible fauna. However, wherever there was coral growth or an accumulation of rocky rubble there was an aggregation of fish, mostly butterfly, damsel fish, trigger fish, and surgeon fish.
Goatfish, flounders, bonefish, and wrasses foraged over the sand, and in midwater there dwelled large schools of mackerel scad, bigeye scad, jacks and unicorn fish. Fish were concentrated above and in front of ledges, with a cloud of colorful species usually being present. Most fish aggregations were near the cleaning station of the louse picking wrasse.
The invertebrates occurring near rocky patches and ledges between 24 and 107 metres were two starfish, sea urchins; beds of a hydrozoan or anthozoans, and spiny lobsters. The spiny lobsters were up to 60 cm long and an estimated 3.2 kg in weight, as compared 0.5 to 0.9 kg of an average reef lobster. In addition, the deep-water spiny lobsters occurred on the open bottom whereas the reef lobster is usually taken in caves or beneath ledges.
Lobsters were sufficiently numerous to warrant calling their grounds “beds”; as many as 60 or 70 were sometimes visible. The sandy plains were studded with sponges and the protruding tubes of annelid worms, and tiny (25 mm diameter) brittle stars were abundant. An occasional cone shell occurred on the sand near rocks.
Between 60 and 107 metres as much as two-thirds of the sea floor was covered by bed of the pen shell Atrina. These black shells were closely packed together, about 540 per m2 and were often arranged in radially symmetrical patterns. A bed of spatangid heart urchins consisting of thousands of individuals spaced about 30 cm apart occurred at 107 metres. Each had a test length of 100 to 150 mm. Although uncommon, species of stony coral were living at 107 metres and the cleaning shrimp stenopus was seen at 55 metres.
Between 107 and 116 metres the sloping plain gave way to a steep cliff which plunged at 60 to 80 degrees from the horizontal. Much of this cliff was smooth limestone and was devoid of macroscopic demersal fauna. Wherever the cliff was textured there were silt deposits inhabited by gobies, long-legged shrimp, and lobster-like crustaceans. Ledges, caverns, and other irregularities offering shelter were crowded with squirrelfishes, moray eels, butterflyfishes and other fishes.
The coils of an anthipatharian coelenterate were also common on this cliff. These coils were formed of a black, brown, or copper-colored substance about three mm thick. They spanned about 75 mm, and their length was 150 to 300 mm. Various starfish, sponges, and sea urchins occurred on the cliff down to 192 metres. Beds of red coral existed between 137 and 183 metres. The cliff was patrolled by snapper, amberjack, wahoo and various jacks. They were either solitary or in twos and threes.
4. Undertake acoustic surveys of the midwater and bottom fauna.
Four dives by this writer were made to determine the suitability of a small submarine for bioacoustics research. An omnidirectional hydrophone was mounted on struts attached to Asherah’s bow. The hydrophone’s output was coupled to an amplifier and tape recorder inside Asherah. Acoustic monitoring began during the decent and continued to the bottom and slopes were surveyed.
When we encountered a sound producing animal, Asherah settled to the bottom with the hydrophone as close as possible. This distance was usually three metres or less. In one bioacoustics dive when I was the observer, I heard the sounds made by what I thought were squirrelfish from a position two or three meters from the entrance to a large cave. I asked the pilot, Mr. Al Stover, if he could get Asherah further into the cave. He then moved the sub well into the cave and all rotating machinery except the gyroscope was turned off while sounds were recorded from the squirrelfish, which I identified by sight and by their burp-burp- burp-burp sounds. The squirrelfish were about two meters from the recording hydrophone on the bow of Asherah.
Sounds were recorded of the following known or suspected sound-producing fish: three squirrelfish and one triggerfish. Often several possible sound-producers occurred as an aggregation, consequently, sounds could not be identified as to source. The recording sites were between 54 and 107 metres deep.
Most of the energy in the staccatos in below 1,000 cps (hz), with the relative intensity shown by the blackness of the bars. These sounds were probably made by a squirrelfish. They are similar to staccatos reported by researcher Howard Winn in 1964 for the squirrelfish Holocentrus rufus. Had a directional hydrophone been employed, this undesired signal would have been largely eliminated.
Variable-interval sounds, typical of those made by triggerfish, were also recorded. They were a series of knock-like sounds 1.5 to four seconds apart and 0.5 seconds long, with frequencies between 200 and 800 cps. No sounds were made by snapping shrimp were obtained, although these shrimps occurred on the adjacent inshore reef.
Not only did we acquire submarine-operating experience with Asherah, but we also obtained valuable scientific information. Of greatest immediate interest are the observations on the vertical distribution of skipjack tuna (aku) and little tuna (kawakawa), about which is little known. The discovery of enormous schools of forage fish in deep water offers and explanation for the occurrence of tuna and other predators there, and simultaneously poses tantalising questions concerning harvesting the small fish for man’s needs. Similar queries arise for the beds of lobsters, pen shells, red coral, and possibly heart urchins. In general, we were surprised at the extent of the deep-water resources.
The Asherah discoveries raise a lot of questions. How are the schools of small fish and the beds of shellfish nourished? What is the nutritional role of the settling white particles that were encountered so often? Are the adjacent depths regularly used as nursery grounds by reef species? How deep does the inshore fauna extend? This last question has interesting zoogeographical implications, for if the inshore fishes also exist in the depths, they may have used the tops of seamounts as steppingstones on their original journeys to Hawaii.
These questions and problems have affected the Bureau of Commercial Fisheries submarine-development plans. More must be learned about the vertical distribution of tuna before the depth capability of our proposed large research submarine is decided. It is desirable to collect samples of the various animals observed for identification, food analysis, and harvesting studies.
Additional data are needed on the environment in the habitats of the various species. These criteria have been kept in mind in planning another submarine operation in 1967. The vehicle to be chartered must dive to 365 metres and have a speed of at least 7.3 kilometres per hour. It must have a manipulator and a receptacle for holding the collected specimens, some of which may be motile. Lighting is very important in the depths that are to be visited. We wish to measure as many oceanographic variables as possible.
Currently several small submarines with the necessary qualifications are available. The planned operation therefore shows indications of being both interesting and successful.
The Bureau of Commercial Fisheries did not use Asherah for any further fisheries research in Hawaii after 1965, but Dr. George Bass used the little submarine successfully in Turkey in 1967.
The above article is an excerpt from Swimming with Fishes, Dr Bob Iversen’s memoir detailing his experiences as a fishery biologist. It is reposted here on Baird Maritime with the author’s permission.
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