Page 6

Looking
At Crabs
With Care

our 7,285-acre estuary, that population estimate results in only 68.6 crabs per acre, although of course they don't distribute themselves that way. The point is, that would be far fewer crabs than most of you remember as a child, and the number of 500,000 begins to take on a different meaning.

     If any of the anecdotal reporting is accurate, it implies that years ago there were probably millions of crabs in the Bay, but no one will ever know for sure. This is the first time that such a study has been done in Pleasant Bay or elsewhere. Previous estimates have been from limited studies of mating crabs on spawning beaches during full moon tides. Our estimate is based upon data collected daily over a full season, covering the entire Bay, using strict scientific protocols, and studying every member of the population from the smallest juvenile to the oldest crab.

     We find it very difficult to fault the preliminary results when there is no other work to compare it against. Nor do we see any reason to question the findings. But that population estimate is just one piece of data. The study is much more than a crab count. The final reports will provide, for the first time, a very accurate scientific picture of a total horseshoe crab colony in a single estuary. We will have a complete breakdown of the population by size, age and gender. We will have an understanding of the health and dynamics of the population.

     Ultimately, stage-based matrix models will be applied to the data and will allow us to estimate population growth and help us understand how the population responds to outside pressures such as harvesting. It will allow regulators to determine what catch limits to apply over a season and still maintain a stable population. The application of this model could extend to any population of crabs on Cape Cod or  worldwide. This methodology can be applied to our own Bay in order to allow limited, but responsible, harvesting of the crab while maintaining a sustainable population.

     We have not entered the study with any predetermined notion of what the answers are. We are impressed with the dedication and thoroughness of the work to date and look forward to the final reports which will be peer-reviewed within the scientific community. We will look to that review as the true test of the validity of the study and its results.

By John Kelsey

     The recent public reaction, from some quarters, to the preliminary results of our horseshoe crab study indicates misconceptions requiring clarification.

     At the time the horseshoe crab "crisis" surfaced several years ago, the Friends of Pleasant Bay decided not to take sides and join the public argument but rather to provide something that was clearly lacking at the time: good information. Our intent was to replace anecdotal observations with good science.

     The scientific body of knowledge regarding the population dynamics of the crab was sorely deficient. Rather than badger the beleaguered regulators for action, we elected to try to give them the information they were requesting. Armed with good information, appropriate regulations are possible.

     To assure complete objectivity in the study we determined that it should be done by the best scientists available and that they should not be from the local community to assure us and everyone else that there was no predetermined bias. We feel extremely fortunate to have a team of marine biologists from the Boston University Marine Program at the Marine Biological Laboratory at Woods Hole, under the direction of Dr. Ivan Valiela, working with us.

     The study is nearing completion, with final reports due in the fall. The biologists were in the Bay all last spring and summer collecting an enormous amount of data, using proven scientific methods. Preliminary, incomplete information is becoming available and one number has generated considerable reaction: That the current population of mature crabs in the Bay is approximately 500,000. The number sounds very large and was initially surprising, even to us. But when we considered a few facts, we gained perspective.

     The current regulations for harvesting horseshoe crabs in the Commonwealth of Massachusetts allow the taking of over 400,000 crabs per year. If the harvest were all to occur in Pleasant Bay the crab would be gone in a few years. Also, in