The story of the USS Indianapolis, the most famous shark attack in history

By Chris Hartzell, All About Sharks (Photo courtesy U.S. Naval History and Heritage Command)

The sinking of the USS Indianapolis resulted in the most famous shark attack event in history. The Indianapolis, CA-35, was a heavy cruiser (often miscalled a battleship in stories) during World War II. In July 1945, it completed a top secret mission to deliver parts of the atomic bomb known as “Little Boy” to the Army Air Force base on the island of Tinian. Because of its mission, the route, radio transmissions, and people knowledgeable about it was kept to an absolute minimum. Tracking of such large ships was done solely on prediction by Command, not verification.

On July 30, 1945, the ship was torpedoed by a Japanese submarine that was known by Naval Intelligence to be operating in the area, but this was not passed on to the Indianapolis Captain (who was later court martialed for failing to zigzag appropriately and ultimately committed suicide in 1968 due to guilt). It fully sank in 12 minutes where approximately 900 of the 1200 crewman went into the water (the other 300 went down with the ship). There were minimal lifeboats and almost no food or water.

On July 31, when the ship was supposed to arrive, the “marker” for it was removed off the Command board as having arrived, without any physical verification. The Port Officer was aware of the overdue ship, but failed to conduct any follow up. Although radio distress signals were sent out during the sinking, and three stations actually received the reports, none followed up on them. One receiving officer was drunk, another had told personnel he was not to be disturbed for any reason, and the third disregarded it as a Japanese trap. As such, the crew was adrift for four days until an aircraft flew over the area and sighted them. Naval Command did not know about the ship’s sinking until survivors were actually spotted by a routine patrol flight.

Once spotted, one of the first responding rescue planes, an amphibious PBY-5A Catalina, attempted to drop life rafts, but had poor success. Upon seeing that survivors were actively being picked off by sharks (one crew reported a shark “twice as big” as a crewmember being kicked away), the pilot disobeyed standing orders to land in open ocean, and landed in the 12 foot seas. The plane taxied around the survivors in an effort to scare away the sharks. They took on 56 survivors (some strapped to the wing with parachute chord), which rendered the plane unflyable. The plane continued to taxi and standby on the water for several hours until the Destroyer USS Cecil J. Doyle arrived, followed by six other ships.

Once all survivors had been rescued, the PBY-5A had to be sunk as it was damaged from the landing and survivors and not able to fly. Over the course of the four days, the crew died off from a combination of exposure, dehydration, saltwater poisoning (crewmembers became disoriented and began to drink the ocean water), and shark attacks. Only 317 crew survived (it was previously reported 316, but Clarence Donner was added in 2017 after confirming he was a survivor). Although the exact numbers are not known, estimates put the total number of crewmen (both live and dead) to be taken by sharks between 60-150.

Oceanic whitetip (Photo courtesy Wikimedia Commons)

Dozens of these were live crewmen. Reports of crewmen screaming and being taken underwater, with blood would rise to the surface along with any lifejacket they had on, were not uncommon over the four days. The predominant shark identified by survivor reports was the oceanic whitetip, but there was a distinct possibility based on later reports from crewmen that tigers were probably also present as well as some “unknown” others (which is highly probable based on the amount of noise and blood in the water). Oceanic whitetips are known for being highly aggressive, especially in numbers and it would not be unheard of for them to attack live people. Tigers are known for this already, so any live crewmembers taken by tigers would not be an unreasonable expectation. Other species of sharks present (blues, mako, etc.) would probably have not been direct attackers, but been present to feed on carcasses and remnants.

Overall, based on the timeframe and reports, there is nothing unbelievable about the numbers of crewmembers taken by sharks, the species of sharks involved, and the behavior of the sharks. The Indianapolis incident is the most famous of shark attack incidents because of the overall story. Due to Naval records not being accurate in how all crewmembers of any naval catastrophe actually die, it is unknown the exact numbers of sailors taken by sharks. However, rough compilations over the years by some Naval historians have estimated the number of military sailors (both live and dead, not including civilians) taken by sharks, by all countries in World War I and World War II, to be approximately 150,000-200,000. These numbers are best guesses by historians, but not able to be substantiated and not involving shark experts (as there really weren’t a whole lot at that time, and those that were had extremely limited data and knowledge).

It was estimated that on average, 10-50 crewmen were taken by sharks per ship going down (this includes dead crewmen killed by something else and then witnessed eaten by a shark). There were an estimated 12,000+ ships sunk between the two wars by all the countries involved. The “total number” also included civilian ships that were forced into military service, submarines, and landing craft. In just WWII alone, the U.S. Merchant Marines lost over 1500 ships. At first the 150-200k seems high. But considering the population of sharks at that time, the number of years included (five years of WWI and six years of WWII), and the many thousands of vessels involved (from all countries), the number does not seem completely unrealistic. In August 2017, the wreckage of the Indianapolis was discovered by Microsoft co-founder Paul Allen in the Philippine Sea lying at approximately 18,000 feet deep. The wreckage is well preserved in three pieces on the ocean floor. Last month, July 2019, the remaining 14 living survivors reunited, as they do every year to memorialize the ship, the catastrophe, and their fellow crewmembers.

WAS IT THE WORST SHARK ATTACK INCIDENT IN HISTORY?

The Indianapolis is so famous because of the overall story: its role in the atomic bomb, its journey, the circumstances of it being sunk and overdue and no one investigating, and then the four day ordeal with survivors. It is probably one of the most “unique” or unusual maritime disaster stories and involves sharks heavily. So it would be understandable how so many titles and headlines have been given to this incident. But does it warrant “the worst shark attack in history?”

That is a tough one to answer with 100% confidence, since much of the evidence is based on reporting by people who aren’t shark experts and weren’t necessarily paying attention to the sharks, but rather on survival. But we can analyze the known facts and come up with a reasonable analysis. There were on the high end of 150 crew, both live and dead, taken by sharks. Of those less than 50 were live men taken by sharks (based on the firsthand confirmed accounts of “at least a few dozen”), with as low a number as 30. So that now puts us at 30-50 live people attacked by sharks. That’s a substantial number for a singular incident.

The defining factor in this incident vs. many others is time. There were four days for which they were exposed to sharks. Generally speaking, when a ship went down, even in those days, exposure wasn’t for such a long period of time. The Nova Scotia sinking is one of the most comparable maritime disasters. It was off South Africa in the Natal region. The first key thing to note was the time factor, with the Nova Scotia having ships on site for rescue within a day.

Then there is the factor of what shark species are prevalent there. The ship sank at the outer regions of the Oceanic whitetip’s range. Whitetips are probably the best scavengers of all the shark species. Like a hammerhead is specialized for picking up prey that is buried, OWTs are specialized at finding food in large open oceans. They cover a tremendous amount of distance searching for food and they are tuned to pick up long distance sources. If every shark species was to be compared to a land species, the OWT would be like the Polar bear.

Where the Indianapolis sank, the population of OWTs would have been significant. So the quantity of OWTs on the Indianapolis would have been far higher than the Nova Scotia. The Nova Scotia would have encountered Tigers, which would have played a much greater factor. But Tigers are not as effective in long range scavenging as OWTs and there wouldn’t have been as many Tigers as there were OWTs. So the number of sharks overall at the Nova Scotia would most likely not have been anywhere near the numbers at the Indianapolis. The number of sharks at the Indianapolis are estimated, based on reports by both the crew and the PBY that came in, to be over 100. The OWTs at the Nova Scotia would probably not have been as high as that, with a handful or more most likely, and total number of sharks a few dozen. In fact, the hundreds of bodies washing ashore as long as a week later tells me the shark numbers and species were not comparable to the Indianapolis.

There is also another maritime disaster that could also challenge the “worst shark attack in history.” The Dona Paz, a Philippine ferry, collided with an oil tanker in the Tablas Strait, a heavy shark area. A total of over 4100 people were lost and only 24 survivors. Sharks were reported to be prevalent in that incident as well. However, again the factors were different than the Indianapolis. A rescue ship was on site within a couple hours and another key factor was that there were thousands of gallons of oil in the water and on fire. The survivors didn’t report any sharks, but later sharks had fed on a number of the bodies. Because most of the victims appeared to be burned, sharks attacking live people was minimal based on the physical evidence found.

So in summary to answer the question…there is no hard evidence to say with absolution on any of this and any answer is based on deductive analysis. But given the exposure time, location, species involved, and miscellaneous circumstances, the Indianapolis with 30-50 live crewmen attacked by sharks would be, based on my personal analysis, justified to be called the “worst shark attack event in history.”