NASSAU GROUPER


In nature there are neither rewards nor punishments; there are consequences.                           (Robert Green Ingersoll).

I recently went to Newport, Oregon on a Club Trip, planning to see the king tides, walk a lot, sleep in a yurt, and hike the nearby Drift Creek Wilderness.  I did all that, but the highlight of the trip came hearing Dr. Scott Heppell talk one evening about real biology—at a brewery no less.

The Nassau Grouper is an interesting fish.  Near the top of the food chain, it gets close to divers, not to eat them, but enough in the way where one really wants it to move. That is almost cat-like.  Yes, like some cats I know, they won’t eat lion fish, an invasive, unless it is speared.  And pointed out.  One apparently was over a reef pointing—“bird dog” was the term used—at a lion fish that he wanted speared.  Life is remarkable.

The Grouper has an interesting pattern of breeding.  They have special areas to breed, the same place, right after the first full Moon after the winter equinox, unless the full Moon is before the 15th of January.  Then they wait another cycle.  Why?  Good question.  Somebody needs to answer it.

When they breed, it is an explosion of sperm and eggs in the water, eventually producing fish larvae, and if a hundred thousand fish were involved, it must have been a remarkable sight.  I use the past perfect, because this number no longer exists in the Caribbean.  Indeed, had it not been for the work of a few people in the Cayman Islands and a few researchers like Dr. Heppell, it would never again occur in the Caribbean.

The Grouper breeds in certain small areas, and it isn’t clear why they do.  Unfortunately, when they breed, it is easy for them to be overfished, which has happened.  Equally unfortunate, once a breeding place is overfished, it never recovers.  This happened first in Bermuda, where they acted early—1970s—and have kept a reasonable population.  The US acted in the 1990s and today there is a 1 in 20 probability that somebody diving in the right waters will see one.  It was once ten times higher.

There were perhaps 50 known areas in the Caribbean where the fish bred, including several around the Caymans.  All have almost completely disappeared, the largest off Little Cayman. I have the GPS coordinates and the time when this will occur. The former area at the other end of the island is gone.  About 15 years ago, two men and a boat, just two, pulled 4000 groupers out of the last breeding area in a couple of days’ fishing.  Not having enough refrigeration, the fish were dumped and allowed to rot. That galvanized action. It is amazing how often when things finally rot, something changes.  It’s better than no change, but it would be nice if somehow we could act sooner.

The Cayman government wished to protect this last area, which  had about 1500 fish left. The fishermen objected for three reasons: (1) the fish would replenish themselves from somewhere else, (2) Babies came from somewhere (not stated) and (3) if it were too late, it wouldn’t matter, which I call the end of the world excuse.

The researchers began studying the fish more, and they did exactly what I was thinking while I listened, now with rapt attention, in Rogue Brewery in Newport, Oregon.  There is a monthly talk here, a great idea.  The researchers first tagged the fish to get an idea of numbers.  They marked a certain number of fish, so that when they looked later, once they knew the percentage of fish in the population that were marked, they knew the population.  It’s a good way to estimate; furthermore, the error of the estimate was known, error not a bad thing but a way of saying that different estimates would have certain values, and other values were just plain impossible, which eliminates common statements like, “anything can happen.”  No, anything cannot happen.  The researchers actually implanted chips into the fish to track them.  They studied currents at various depths by placing  sondes at a specified depth to track currents, learning that during the full Moon, the currents did loops.  Why?  We don’t know.  Why are certain places used for breeding?  We don’t know that, either.  But we know a lot more.

We know that the fish don’t swim from one Cayman to another, over a trench 6000 feet (1800 m) deep.  That fact wasn’t known.  We know that because sound buoys at the other Cayman islands didn’t hear these fish.  We knew where the fish tended to live, and it was all around Little Cayman.  At the time of the proper full Moon, we learned they didn’t all go at once to the breeding area.  They went individually, often taking several trips around the island before they arrived.  That last piece of information was important.  It meant that making the breeding area protected around breeding time was insufficient.  The fish were more on the move before and afterwards, and they needed to close the whole island to fishing for four months, where the fish were not so widely dispersed.

As for the comment that fish would be replaced from some other place, that was impossible, for there were no other places left of note in the Caribbean.  Overfishing has consequences; sure, it’s fine to have a job, but too many jobs in areas that aren’t sustainable lead to nobody’s

having a job.  It’s sort of like logging. Somehow in all the “job” talk, nobody mentions “fewer children.”  Maybe that’s because we are stuck on “growth,” when “growth” can’t continue forever. Does anybody think China can grow at 8% for the next century?

Spearing fish was banned, along with limiting diving.  The fish weren’t coming from anywhere else.  Once the fell below a certain population, they stopped breeding.  They’re gone. No more job.  Once the fish are gone, work is gone. The researchers also learned that the fewer the fish, the more time they spent in the breeding area, and the higher their risk.

There was, however, good news in all of this.  The numbers have actually risen the past few years.  Mind you, they aren’t great, only about 2500 now in the breeding area, but they aren’t 500, either, and this increase had never been documented previously.  We have some understanding of their life cycle and biology, and the Cayman government not only continued the ban until 2019, they have written legislation citing the biology known.  The Caymans have become the model for how to manage a fish.  It’s a shame it took several thousand rotting fish and overfishing to make this change, but at least it was changed.  Whether the fish ever return to the area where they were before is not known. The fish do check out the old site near breeding time, but none has gone back there to breed.  If that ever becomes a breeding spot, it would be marvelous.

Doing the right thing has consequences.

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