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STATUS OF SHELLFISH DEPURAT ION IN NEW YORK
David H. Wallace
The State of New York has two interests in terms of the Shellfish Sanitation Program. New York is one of the biggest consumers of shellfish in the United States, with its big population. We have a very real interest in this product in relationship to the health of the consumer.
Secondly, we have another reason in that we are a producer of shellfish. in fact, we are the largest producer of hard clams. We produce also oysters, mussels and scallops. So we have another interest in terms of the sanitation program dealing with the problems and relationships involving our industry and our control program.
In New York we look upon the Shellfish Sanitation Program as a community project. I am talking about the community in terms of all the people who are involved in it. We feel that we have to maintain a close working relationship with our industry, and it does my heart good to see the turnout of our industry here in this workshop because they realize the very vital nature of this whole deve lopment.
I want to emphasize that we believe we have an obligation and responsibility to our consumers as well as to industry in all of the standard ways that I am sure every other State here is trying to do. As a result of the problems that have been developed and the programs that have been deve loped, we have been greatly accelerated in our sanitary surveys because we have about 600,000 acres of shellfish ground; 450,000 which is open and 150,000 which is closed because of pollution. We are greatly accelerating our enforcement efforts to police these restricted areas so that the shellfish are not being bootlegged out to the market, and we are trying to do this at every level - the county level, and the State level.
The third part of our program is one of the things which we believe at the present time is a practical approach to this problem of shellfish in contaminated areas. This is to have relaying of shellfish from contaminated areas to clean waters. As a result of the support of our industry, we were able to launch an aggressive program of relaying in the summer of 1964 which we will greatly expand in the coming years.
The other part of the program is this matter of pollution control and abatement. We have talked about pollution and its ever expansion and I was rather appalled at the conditions that Phill Goggins outlined in Maine. We feel that we don't have to be hopeless about this question of whether or not we can control pollution because we don't believe this is a fact.
In the State of New York at the present time we have an aggressive program in pollution control and abatement. Within the next year we believe there will be areas as much as 40 square miles which we will be opening for the taking of shellfish areas that have been closed for the past 40 years. There are possibilities and opportunities to reserve a portion of this area for shellfish cultivation, and I think we can't lose sight of this as part of our program.
The last item is this matter of depuration. Where does it fit into a program which would be carried on in the State of New York?
We don't know, frankly, where this fits into our picture at this moment. We feel we don't know enough about it in relation to the species we have; as for example, hard clams. As a consequence this year, in cooperation again with our industry who are working side by side with us, we are setting up a pilot plant for hard clams -- a depuration plant. We feel that there are many inherent problems in this matter of purification of hard clams, particularly in areas where we have a wide range of temperatures, with the clams being forced to hybernate during the wintertime, or something approaching this, and going through long periods of the year not breeding at all.
We have done some very preliminary tests through the cooperation of the State of Rhode Island and the Public Health Service and the Rhode Island Experimental Lab. I am sure you are going to hear about this next, and I will be brief. These tests indicated that we must have a great deal more study on the matter before we, as a responsible agency, could certify shellfish from a purification plant.
I might say that the State of New York had purification plants some 40 years ago at the time, or just a bout the time when the present certification program went into effect. They had some satisfactory results at that time in the purification of hard clams. I have talked to the people who participated in the operation of one of the early plants in fact our present study will utilize one of these plants and one of the original tanks and they thought this process at that time was not a desirable technique, and the process was abandoned by the industry and the State,
We believe that purification is not a panacea for the shellfish industry in the future. We must have a balanced program doing all of these things. Even with purification plants, if we have inadequate enforcement to prevent boot legging this could bypass a purification plant as illegal operations bypass our control system today. If this happens the program would be of no value.
| agree with the previous speaker about the variability of living animals. Pasteurization of milk is one matter; pasteurization or purification of water is one matter, but when you are dealing with individual living animals they vary individually just like people!
RHODE ISLAND DEPURATION STUDY
Manuel T. Canario, Jr.
Division of Fish and Game
The shellfish industry of Rhode Island depends almost entirely upon the supplies of the hard clam or quahaug, Mercenaria mercenaria. Since 1955, when a peak of five million and twenty thousand pounds 15,020,000) of quahaug meats were harvested there has been a gradual decline in amount harvested, and the number of diggers. More and more of our marine areas are in danger of becoming polluted, threatening the shellfish industry. Two major areas, the Providence River and Mount Hope Bay, are closed to shellfish harvesting due to pol lution. It has been estimated that 600,000 bushels of quahaugs are in the polluted waters of the Providence River and 400,000 bushels in the Mount Hope Bay area.
In the hope that some of these quahaugs could be harvested and cleansed for market, the Rhode Island Division of Fish and Game assembled a pilot size quahaug purification plant, and in cooperation with the U.S. Public Health Service, is working on the deve lopment of techniques for the control and processing of shellfish. The unit consists of two plywood tanks with fiberglass coated interiors. Each tank is capable of holding twelve bushels. An ultraviolet lamp unit, patterned after the "Purdy'' unit, was used to disinfect the saline water used in the purification tanks.
The question as to which process would be best suited arose. Should waste water be returned to the harbor after a single pass through the purification tanks, or drain and flush the tanks one or more times during the length of the trial, or recirculate the tank water continuously from the tanks to the ultraviolet lamp unit? Since the water had to be heated to operate during the winter months, it was decided that recirculation of the water continuously was the most expedient. Modification of the pilot plant enabled operation of one tank at 55°F. and the other at 70°F.
The influence of the tank water temperature and the rates of the weight of quahaugs to the volume of seawater, on the elimination of coliform organ i sms by the hard clams was investigated in a 2 x 2 factorial experiment. Five of ten trials had been completed before the suspension of the project since the specimens failed to show a high enough coliform reading to measure. This apparently was caused by the reduced syphoning of the clams as the water cooled. Periodic checks he re maintained until by the 10th of May, 1964, when the numbers of coliform again rose to a sufficient level for analysis.
Shellfish for the experiments were obtained from a closed area in the Providence River. In the summer, coliform counts in this area indicated up to 10,000 per 100 ml. of flesh and 20,000 to 43,000 per 100 ml. of water. Yet, for example, tests taken on the 23rd of March, 1964, indicated a coliform count of 1.8 per 100 ml. in the quahaug and readings of 540 coliforms per 100 ml. for the surface and 79 coliforms per 100 ml. for the bottom samples of water in this area.
The water in both tanks was recirculated through the ultraviolet lamp chamber at 30 gallons per minute which correspond to a change of tank water three times an hour. Two submersible pumps in each tank provided circulation within the tanks. A preliminary trial without the submersible pumps showed that the dissolved oxygen in the strata containing the shellfish was quite low. Little dissolved oxygen stratification was noted after the pumps were functioning.
Respiration in the warmer water was greater, demonstrating that respiration is dependent upon temperature. At 22°C. Mercenaria mercenaria activity pumps for approximately 90% of the day, but with a drop to 5°C. activity decreases, and below 5°C. hibernation of the individual occurs.
Twelve quahaugs, in each tank, were numbered and observed for activity. Though the measurement of activity was rather crude, one could follow the increase of activity as the water warmed. The activity reached its peak before 48 hours and gradually lessened and by 72 hours most had ceased. The amount of dissolved oxygen in the water decreased as activity increased and increased as activity ecreased.
Beginning with trial No. 8 difficulty was experienced maintaining the 7°C. temperature differential as both tgnk temperatures approached room temperature. As water temperature rose above 75°F. a new problem presented itself as the quahaugs spawned during the trials. Visual observations of the quahaug's movement became impossible at times. Dead shellfish in a tank tended to upset the trial if they were not removed, for the coliforms will multiply in dead quahaugs and possibly when spawn fills the tanks. This view is substantiated by the results of a study in storing two species of clams, Tapes japonica and Prothothaca staminea, of the Pacific Coast at 20°c. coliform MPN counts increased by a factor of ten in one day. It is acknowledged that coliform counts of shellfish in-trade are expected to be higher than when harvested. If the coliforms do multiply then their numbers as a measure of pollution is largely negated. For this reason the determination of E.C. gas positive organ i sms is useful. The E.C. gas positive organisms did not seem to multiply in the present experiment.
It is our belief that such purification as is going to take place with the hard clams will occur within the first twenty-four hours. We were strengthened by our belief by the notes kept on the activity of the clams in the tanks where we noted the appearance of waste from the quahaugs, and something of their siphoning and oxygen consumption. Most fecal matter was expelle by the quahaug between the sixth and twentieth hour after entering the tanks for purification.
These trials showed that the ultraviolet system of water recirculation is a practical method of purifying the hard clam. Further tests should substantiate these findings. The process would help to allay consumers' fears of purchasing contaminated shellfish, and should be a boon to the shellfish industry.