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Food Chain in Motion -- Kevin Sullivan's Tale

In my 27 years as a special agent with the National Marine Fisheries Service Office ofLaw Enforcement, I've spent a lot of time on the ocean. But the single most spectacular event I witnessed took place over twenty years ago in what is now the Stellwagen Bank National Marine Sanctuary.

I can't quite recall the date. I believe it was 1978, perhaps 1979. I vividly remember the day. It was a crisp autumn afternoon. With little wind the water was like a mirror reflecting the west heading sun. Long, dark shadows followed the Massachusetts Environmental Police patrol boat. I had joined a day-long mission with two environmental police officers. We were on the lookout for fishing vessels taking more than their legal share of giant bluefin tuna.

Stellwagen Bank, which had not yet been designated as a National Marine Sanctuary, was, and still is, a popular fishing spot for the giant fish. You have to understand a bit about giant bluefin tuna to see why a fishermen would break the law to catch them. True to their name, giant bluefin tuna are enormous creatures, weighing as much as 1200 pounds. They can swim at speeds of up to fifty miles per hour. These fish are called "highly migratory species" due to their lengthy journeys from sea to shining sea. Even back then, fisherman make a pretty penny selling these fish in Japanese markets. They'd place the fish individually into large wooden coffins, load them onto a 747, then ship them straight to Tokyo, where dealers would pay up to 25 dollars a pound for them.

If you do the math you'll understand why catching just one giant bluefin tuna makes for a profitable day at sea. For obvious reasons, some fisherman would like to catch more than one. But by federal law, a fishing vessel can take only one giant bluefin tuna per day. Tuna stocks had become unstable in the mid-70's due to overexploitation around the world, especially by distant water longliners. Scientists feared that populations would collapse if fishing pressure kept up. The state officers and I wanted to see to it that this didn't happen. We weren't just enforcing the law out there; we were ensuring the survival of the majestic giant bluefin tuna. At the same time, we had a genuine concern for maintaining "a level playingfield" for the fishers who expend significant time and money in the hunt for their valuable prize. Those who fail to achieve their catch are said to have been "tuna wishing".

Well, the two officers and I were merrily making our way along the southwest corner of the bank, not too far from Provincetown. As always, we tried to be aware of breaking water to avoid collisions with marine mammals such as the highly endangered right whale that frequents the Bank. One of us spied white water splashing about a three iron from our boat. It was a school of very scared sand eels leaping for their lives above the surface of the water as hungry bluefish cunningly circled underneath awaiting their appetizers. The jumping sand eels were a familiar sight, typical of bluefish feeding frenzies. Pound for pound bluefish are probably the fiercest fighters in the sea. But they were no match for what we then saw: a school of bluefin tunas bursting though the water just behind the bluefish. The table had turned. The predators became the prey. The bluefish leapt from the water, frantically seeking escape from the powerful jaws of the encroaching tunas.

Back on the ship we'd fallen silent as the spectacle of the food-chain in action unfolded with the shocking appearance of the oceansŐ ultimate force. The tell-tale traits of bright white on black and the high triangle fins instantly announced the presence of killer whales in hot pursuit of the marauding bluefins. Killer whales aren't so common on the bank, but when they're there, they like nothing more than a bluefin tuna dinner.

My best guess is that the scene lasted about thirty seconds. I lost track of the time, though. To me, time stood still, as if the whole event was a snapshot of a natural process. We could see every level of the food chain at work, except for the microscopic plant plankton and the somewhat larger animal plankton that serves as the sand eels' food. Looking back, I realize that if I'd had a good camera handy, I could have taken a picture that would have enabled me to retire twenty years early!

 

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