A white dot. That’s what it was. First very faint, then getting bigger and bigger. I was astonished at what it turned out to be – the white nose of a shark about two feet long. The whole encounter did not last more than 10 seconds and at the end of this short bit of time, judging from its behaviour, I think I scared this little shark.
Here is how it happened. On the same cruise with Gene Nakamura on the Research Vessel Charles H. Gilbert in the summer of 1968, I had an opportunity to again test the swimming behaviour of threadfin shad, a small sardine (Dorosoma petenense). I don’t remember what Gene was doing, but I was alone in the water some distance from Gilbert and had in a cloth bucket about 300 or 400 shad. Gilbert was hove to fairly close to shore – the depth of water would have been about 500 to 600 feet. The sea was calm, and the weather was sunny.
“I was fixated on the dot, which kept getting bigger and bigger and bigger.”
When I felt the conditions were satisfactory, I up-ended the bucket and broadcast the shad. They instantly formed into rather large ball, but in a second or two, the large ball of shad turned into a shining vertical column that swam directly down and away. They disappeared from my view in less than 10 seconds and my estimate of their depth when they disappeared from my vision about 75 feet. I assumed they continued swimming until they reached the bottom. What they did after that I have no idea. The main thing I learned was they swam downwards and did not stay at the surface. This would be useful information to commercial fishermen who might use them as bait for fishing for aku.
Shortly (10 seconds) after the shad disappeared, I saw a small white dot in the water about where the shad disappeared. I said to myself, “That’s odd, I wonder what that white dot is.” I was fixated on the dot, which kept getting bigger and bigger and bigger. When the dot was about 25 feet below me, I realised the white dot was the white nose of a shark, and that it kept getting closer and closer to me.
“The only explanation I can think of is that when I was spread eagled at the water’s surface, I became a very large object, casting a large shadow, and much larger than the shark.”
When the shark got two or three feet from me, I could see that it was not a very big shark. At its closest approach (ca. two feet) the shark abruptly turned 180 degrees and swam right back down towards where the shad disappeared. When the shark reversed course, I got a good look at its underside and flared pectoral fins. From this I estimate the length of the shark to be about three feet long. When it turned, it was so close that I felt the swish of the water from its tail.
Now this may be an interesting tale, but to me the most interesting part was trying to figure out why the shark got so close to me and then abruptly changed course 180 degrees. The only explanation I can think of is that when I was spread eagled at the water’s surface above the shark, I became a very large object, casting a large shadow, and much larger than the shark, which did the most sensible thing – it reversed its course. I have not researched this sort of shark behaviour, so there may other explanations from some of my colleagues who know more about shark behaviour than I do.
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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Bob Iversen is a retired Hawaii fishery biologist who spent 40 years studying tuna and other fish in the tropical Pacific Ocean. He is a former officer in the US Navy, and initiated the “mental health of seafarers” movement that has now taken off worldwide.