Each week, the Observer on Sunday take a peek back more than 40 years to show our readers a little bit of what happened in that era. This week’s story explains the mystery of why fish were being found dead in the bay.
Consequent on our “Something fishy in the Bay” story last week, Dr. C.R. Gilbert and Mr. Phil Heemstra called in our office to give us some information regarding their activity here.
Dr. Gilbert has been on the staff of the Florida State Museum for 5 years and prior to this worked with the Smithsonian Institution. He first came here on his way home from Costa Rica in 1963.
He returned in October 1964 with a Dr. James Tyler of the Academy of Natural Sciences in Philadelphia and they collected fish for about two weeks on our reefs and around the island. The fish in which he is particularly interested are the very small ones which live inside the coral of the reefs.
Dr. R Tucker of this same Academy has recently written an extensive monograph on the Molluses of the Cayman Islands.
As a result of his previous visit, Dr. Gilbert applied for and received a research grant from the American Philosophical Society to study the fishes of the Cayman Islands and to write a paper on his findings. The island of Cuba is the centre of the evolution of West Indian fish and as the Cayman Islands are geologically part of Cuba this seemed an ideal place for study.
The poison they used to kill the fish is made from the root of a plant called Derris which is marketed under the commercial name of “Rotenone”. It has to be specially ordered and cannot be purchased in a normal drug store. It is much too expensive to be used commercially for fishing and it is only when a research institution give a grant that the poison can be purchased. This is done because it is the best way to catch fish for scientific purposes. It was first discovered when South American Indians were seen cutting up the Derris root and putting it into the water to catch fish for food. It merely cuts off the oxygen so that the fish die and is no danger whatsoever to human beings. It is used by all U.S. State Agencies for capturing fish for marine study.
Dr. Gilbert mentioned that the herring family, which includes our sprats, are most susceptible to this poison, hence the reason for the school being totally destroyed in the bay last week. However, next day, in the same area Mr. Heemstra saw more than one school of sprat with many fish which proves the effect of the poison in the water does not last for any length of time.
Upon enquiry as to whether permission to catch fish in this way normally has to be obtained from an official source, D. Gilbert indicated that in the U.S. and the Bahamas permission has to be south but, so far as he is aware, not in any of the other West Indian islands.
Normally these men operate out of the reef where the currents soon disperse the fluid of which they use about 1 qt. for each collection, but in the bay last week they were trying out some poison which did not appear to be very effective in the deeper water and there was not much current to wash it out so that it was more concentrated.
The purpose of the present study is to publish a paper which, it is hoped, will attract people interested in fish to visit the islands and should, in this respect, increase our tourist industry.
Dr. Gilbert and Mr. Heemstra would express deep regret for the trouble and concern caused to local people.