A tragedy of the commons averted? 

(Based on an article entitled "The Bermuda Fishery" by J Butler et al. in ENVIRONMENT vol 35)



For over 300 years, fishermen in Bermuda were able to fish essentially wherever they wanted and to use whatever means they wanted to catch fish.  In 1990 however, the Minister of the Environment, Ann Cartwright-DeCouto, took the bold step of banning the use of the most common fishing method, fish pots, with the result that nearly all of the fishermen in Bermuda were put out of business.  Why did she take this drastic step?  What has happened in the last decade since the ban?  

Let's look first at the recent history of fishing in Bermuda to see what happened prior to the ban in 1990.  The most cfishtrapommon method of fishing after World War II was the fish pot.  Rather than fishing with a hook and line, the fish pot was a rectangular cage with a funnel entrance for the fish to enter but, since the opening narrowed, once inside they couldn't get out.  The pot was baited with dead fish, set in waters of different depths and marked with a buoy so that it could be found again.  This provided an efficient method of fishing and helped the fishermen to supply the local population and tourists with fresh fish.  During the 1980's, there was a dramatic rise in the number of people living on the island.  In addition, the strong economy of the US resulted in increased numbers of American tourists coming to Bermuda.  All (or at least many) of these people were interested in eating local fish!  What does any enterprising businessman do when demand increases?  They try to make more money by raising prices and by supplying more fish! 

To catch more fish, the simplest thing to do is put out more pots.  That is exactly what happened and, since people were making good money fishing, more people became fishermen.  Take a look at this figure which shows the amount of all kinds of fish reported as caught by the fishermen.


The first thing to note is the dramatic increase in the amount of fish caught in the early 1980's due to the increased effort by the fishermen.  Clearly they were successful for a short time.  The second point is the rapid decline in fish caught at the end of the decade!  What happened?

Lets look at the same data but in another form.  This figure shows the amount of two kinds of fish caught in each trap.


You can see that the number of groupers in each trap had been dropping from 1975 when data was first collected and the amount of other reef fish was increasing during the time when the total amount of fish was increasing.  If you add the data for the two kinds of fish together, you get the data in the first figure.  Now it is important to realize that groupers are the most prized fish to eat on the reef and that most of the other types fish were not even kept but were thrown back as "trash fish".  However, once the amount of groupers caught dropped (and remember this is when demand was increasing), the fisherman began keeping the trash fish and trying to sell them.  How did they sell to the consumers who wanted groupers?  Well, a filet or slice of fresh fish pretty much looks the same whether from a grouper or from a fish such as a parrotfish! 

So what if it became more difficult to catch fish, just keep putting out more pots. So long as the trash fish tasted good and sold well, who cares?  That's where an understanding of the ecology of the reef is important.  The groupers are predators and so act to control the number of other fish.  Once they were removed due to fishing, then the numbers of the trash fish could increase in what ecologists call "Top down control" of populations.  The trash fish are a varied lot, eating algae (herbivores) or scraping food off rocks or eating coral.  However, any effect of increasing numbers of fish pots wasn't felt before the fishing effort began to catch the trash fish leading to the crash in fish catch in the late 1980's.  Without predator fish or trash fish to control the growth of algae on the reef, the entire ecological balance was upset. 

At first, the Government tried to limit the number of pots to limit the decline of fish.  That didn't work and the result is the title of this discussion; "the tragedy of the commons".  The commons is some land in the center of a town (mostly in New England or England) where all the farmers could graze their cattle.  Since anyone could use it and no one farmer owned it, each farmer figured if he didn't use it, the others would so they each kept grazing more and more cattle until there wasn't any grass left.  A tragedy!  The commons in Bermuda is the reef itself where the fishermen figured that the other fishermen were putting out more pots than they should and besides, there were plenty of fish anyway so why not! 

We still need to understand the causes of the rapid drop in fish caught (that first figure!) although we know that it represents mostly the the trash fish.  First, the fish pots can easily become lost if they lose the float marking their location due to a storm or, especially if people are hiding the illegal ones from the fish warden by hiding the float below the surface.  Since the pots were being made of metal instead of wood (Look closely at the fish pot image and you can see that it is an old style wooden one) which degrades as in the old days, a lost pot will keep fishing for a long time.  Even though no fish are removed for human use, the pots continue killing the fish who are trapped inside since they eventually starve to death. This is called "ghost fishing".  Second is the fact that trash fish had always been caught in the pots but had been thrown back.  Unfortunately many didn't survive being in the air.  However, since the data in the figures is based on what is reported by the fisherman, and since they didn't bother counting the trash fish if they couldn't sell them, no one knew how many other fish were being killed for all of the years before the 1980's.  Both the ghost fishing and the lack of accurate reporting therefore led to the reports of reduced numbers of fish on the reef.  Once fisherman focused on catching the trash fish, boom, there was a rapid drop in numbers because so many fish had already been killed! 

Given the data just discussed, it seems logical to ban fishing doesn't it?  The fishermen certainly didn't think so because they could no longer earn a living.  Why didn't the fishermen believe the data and what did they think the problem was?  Pollution was their scapegoat (look up this word, it comes from the Bible!) rather than overfishing.   However, measurements taken by BBSR over many years showed that there was no increase in pollution from sewage or from excessive plant growth or other possible sources. 

The ban of fish pots started in 1990.  After nearly 9 years, has there been any increase in the number of fish?  Recent results clearly vindicate the ban as fish numbers are increasing.  Two species of parrotfish, the Princess and the Redband Parrotfish, increased by 1993

but the Stoplight and Queen Parrotfish didn't!  Even the scientists thought that there would be a rapid increase in numbers since there were few predators (groupers are a major predator but were gone) and there was plenty of food since the algae had been growing without the fish to eat them.  They are still investigating the slow response but some of the ideas for the slow response include the possibility that there were so few fish left that they couldn't all find each other!  Another thought is that since Bermuda is small, many of the baby fish are swept out to sea on the tides and cannot make it back so that they die.