IMEP #129 - Hydraulic Cultivation of Marine Soils for Clam Mariculture 1985

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IMEP #129 - Hydraulic Cultivation of Marine Soils for Clam Mariculture 1985
National Research Council Presentation
"Understanding Science Through History"
August 14, 1985
Miami, Florida
Timothy C. Visel
Sea Grant/Marine Advisory Service UCONN
Viewpoint of Tim Visel – no other agency or organization
This is a delayed report
June 2023
Thank you, The Blue Crab ForumTM for supporting these Habitat History reports


A Note From Tim Visel – May, 2023
This paper was presented while an employee of the University of Connecticut.  It was not reviewed by peers and is based upon my observations of hydraulic harvesting of soft shell clams on Cape Cod and the hard shell clam in Connecticut.  This paper and two others were combined for a presentation for the Rhode Island Shellfish Conference, August 27, 1990 and the Madison Shellfish Commission on September 20, 1990 (Madison Town Hall).  This paper is not an official UConn Sea Grant publication, it has no CTSG number and I most likely have the only printed copy.  Three presentations were combined as a single report in May, 2009 – as "The Hydraulic Cultivation of Marine Soil to Enhance Clam Production," which included an extensive literature search.  Within the past decade, marine soils have begun to be recognized and mapped.  Their significance to aquaculture has also been recognized (subaqueous soils) in 2017 (See Subaqueous Soil Survey, Mark Stolt, University of Rhode Island, James Turenne and Maggie Payne USDA-NRCS).  The cultivation of marine soil (before and after trials for CEC, sulfide, pH) for clam production, however, remains a much under-studied research area – my view, T. Visel.

Abstract: NRC Presentation
Observations of marine soils were made in Massachusetts and Connecticut estuaries from 1980-1985.  All involved the field operation of hydraulic shellfish harvesting equipment utilized in the hard shell clam fishery Mercenaria mercenaria and soft shell clam fishery Mya arenaria.  Interviews with small boat fishermen and larger shellfish companies provided information on the importance they place upon proper soil preparation.  Additional scientific research in this area also concludes that increased shellfish production is possible with plot rotation, cultivation schedules and marine soil manipulation (Volk, 1984, personal communication, T. Visel).  In this paper, I would like to discuss the application of the successful concepts and procedures of terrestrial soil management to marine soils utilizing underwater cultivation equipment.

Clam Culture
Clam fisheries are important sources of fresh seafood throughout the world.  Natural populations are found in estuarine intertidal and subtidal substrates (soils) of estuaries.  Clam fisheries are also located in deeper offshore areas that are exploited by the use of larger vessels.
Clam mariculture can be of two basic culture procedures of on-bottom and off-bottom, similar to oyster culture.  With on-bottom, hatchery seed can be broadcast onto bottom leases or plots.  The seed can be protected from predators and natural forces, such as storms, etc.  Off-bottom culture can be in trays or racks containing soil or in marina dock systems.  One method consists of hatchery produced seed Mercenaria mercenaria being placed in raised boxes containing 5 cm to 10 cm of soil.  They are arranged in rows in subtidal areas in 1 to 3 meters of water.  The containers, measuring 1m by 2m, have plastic mesh screening, top and bottom, to allow for water and nutrient circulation.  The sides are constructed from wood 2.5 cm thick by 25 cm high.  Periodic thinning of stock and removing fouling organisms from the cages add to the labor intensive aspects.  In some coastal areas, opportunities exist to increase local supplies of seed clams for mariculture.  This is made possible by cultivation and predator protection, known environmental constraints.  Clam production can be increased through environmental improvement of the soil (Burton, 1973).

Low cost, low tech cultivation equipment ideally suited for small scale fishermen is under harvest use today.
Shallow nutrient-rich estuarine soils may especially be suitable for cultivation principles listed above for marine soils.
First, I want to thank Daniel O. Suman for inviting me to the National Research Council meeting regarding Innovative Technologies for Artisanal Fisheries.  I hope that you will find my presentation interesting and helpful in producing food from estuaries throughout the world.
The topic of my presentation is the cultivation of marine soils for the production of mollusks.  This has been an interest of mine for about ten years.  I have tried to collect as much information as possible with some anecdotal and historical references to the product of hard and soft clams.  I want to begin with a brief explanation before I describe equipment and techniques.

I would like to start with a brief introduction of the concept of marine soils.  For too long, we in the research and academic communities have described estuaries' bottoms as just that, bottoms.  Certainly, no one could argue that these terms do not sufficiently describe the water body or basin but does a terrible injustice to its food-producing potential as a soil.

The bottoms of the estuaries contain soil of all descriptions.  Only when you examine the literature regarding inundating water flood plains, do you find references of it as a soil.  Once you accept the fact that marine soils exist, the rest is easy and easily understood as a feature of soil science.
The area of the country I worked in New England includes the states of Rhode Island, Massachusetts, and my home state of Connecticut.  It was surprising for me to find how the cultivation of marine soils had lagged far behind that of terrestrial soils and how the concept is underresearched – the impact of oyster culture on the habitat benefits to the hard clam (pH moderation).

My first exposure to the technique of cultivation marine soils came from a retired oysterman, George McNeil in Clinton, Connecticut.  As part of the Cooperative Extension System, his description of oxen-drawn plows for cultivation on the beach off West Haven, Connecticut in the 1880's for soft shell clam astounded me.  The teams of oxen would cultivate large, subtidal flats each spring and again in the late fall.  One of the earliest findings from such a practice was the observed increase in clam sets and faster growth of seed clams.  George McNeil detailed how the area "The beach" could produce 10,000 bushels of soft shell clams a year, and was combined with an oyster fattening operation.  Oysters would be laid out on the beach in June in squares and fatten up in the fall prior to the clam harvest.  Upon researching the historical literature, I came across a reference date 1881 from George Goode "After many trials of all sorts (types) of plows and cultivators, surface and subsoil and proving them unadapted to the turning of the dense, wet heavy mixture of sand and mud, Mr. Wheeler Hawley of Bridgeport succeeded in inventing a light plow, having a thin narrow, steel mold board which did the work satisfactorily." (US Fish Commission)

The question is "Can soil cultivation improve clam sets, increase growth and be managed similar to terrestrial agriculture?"  I believe so.
Another example, prior to 1956, all clam dredging performed in Connecticut was what is now termed a dry dredge.  That is it was towed from a fishing vessel mechanically.  A wet or hydraulic dredge soon came into use in the late 1950's and 1960's after many oyster companies turned to hard clams to boost income and make up for rapidly declining oyster harvests.  This is when oyster companies, such as Dolan Brothers, reported increased clam (hard clam) sets below seed oyster plantings.  A wet dredge utilizing streams of water to emulsify the soil, thus loosening up clams for easy entrance into the bottom dredge.  Not only did dredge mortality (those clams broken or crushed) drop to less than 4%, oystermen noticed increased clam sets.   In fact, they soon learned that if they cultivated clam beds in late July-August (which the oyster cultch had been planted and seed oyster season closed), good sets can be obtained.  Further, if they rotated their leased beds under cultivation harvest schedules, yields increased dramatically.  Connecticut today produces more hard shell clams than it did 100 years ago even with 70% of its shallow waters are polluted (bacterial closures).  This rotational cultivation technique has been an accepted industry practice for more than twenty years.

Also, every bayman or shellfisherman will tell that it is beneficial to work the "bottom."  This work can be accomplished by hand implements, such as rakes and tongs.  Unfortunately, the benefits of this soil cultivation do not result in great shellfish yield.  Being a common property resource, few, if any, rotational cultivation trials or long-term catches have been possible.  On private leased or granted grounds, long-term observations are known.
Dolan shellfish operations noticed on log journals changing marine soils after hydraulic clam harvests.

Clams –
Historical information details cultivation experiments with plows at the turn of the century.  Massachusetts reports mention clam bottoms as soils – David Belding (1912) on Cape Cod and Brown University soft shell clam researcher A. D. Mead in Rhode Island around 1902.  In researching the topic in 1984, I came across a Clinton, CT article (1902) in which soil experiments described as new or placed sand as having heavy soft shell clam sets.  This man-caused sand was monitored for new sets, opening the possibilities of soil cultivation.

Oysters –
Oysters have been successfully cultured for centuries.  Until recently, much of this culture was based upon manipulation of seed beds.  This allowed increased production of seed for transplanting to offshore to grow out grounds or protected near shore areas.  Various technologies and procedures have been developed for predator protection, harvesting equipment and cultivating techniques worldwide, such as the transplanting such as seed collection.
From seed to grow out beds, soil cultivation and pH monitored could be an important consideration in mollusk soils.  It is reported in US Fish Commission reports "Sudden clam harvest expansion linked to storm activity – such as barrier spit breaks."

Small Boat Operations – Hand Digging and Elimination of Environmental Constraints
It may be possible to implement soil cultivation procedures long utilized in terrestrial agriculture to eliminate or mitigate soil conditions, such as soil circulation and pH.  Buried shells found in Clinton Harbor crumbled in black organics from acids or pH, soil composition and water quality in the soil itself.
In some coastal areas, it may be possible to increase shellfish production by applying successful concepts and procedures of terrestrial soil management to marine soils.  These soils (land agriculture) have been studied for centuries.

In some coastal areas, an opportunity may exist to increase clam production by the application of terrestrial soil management procedures and concepts to marine soils.  These procedures, such as cultivation schedules plot rotation, soil manipulation may eliminate environmental constraints upon clam populations, such as low pH.

I have prepared a slide presentation for hard clam hydraulics – Madison, CT and two presentations for Dennis, MA salt ponds hydraulic jet or wand and finally a shellfisherman's project Bourne-Sandwich Shellfish Association experiments in Bourne, MA.  Slides will show growth bands on soft shell clams in sandy cultivated soils as compared to high organic soils (pH concerns) in which growth is measurably slowed.  This equipment is presently being used in small scale fisheries in shallow water in Massachusetts and Connecticut.
I will answer questions after the slides – Thank you!

Appendix #1

National Research Council
Board on Science and Technology for International Development
Innovative Technologies for Artisanal Fisheries
Meeting Program

August 13-16, 1985
Miami, Florida


August 13 (Tuesday)    Arrival during afternoon
            Key Biscayne Hotel
            701 Ocean Drive
            Key Biscayne, FL 33149

7:00 p.m.         Informal Reception, Palm View Room
August 14 (Wednesday)   Rosenstiel School of Marine and Atmospheric Science (RSMAS)

9:00 a.m.         Welcome, purpose and expectations of Committee
            John Sainsbury, Chairman, Steering Committee
            E. Griffin Shay, BOSTID, Professional Associate
            Daniel Suman, NRC Fellow

9:00 a.m. – 12:00 N      Presentations by committee members and invited specialists
9:15 a.m.         Edward Harper
9:30 a.m.         John Sainsbury
9:45 a.m.         John Shortall
10:00 a.m.      Steve Drew
10:15 a.m.      William Alevizon

10:30 a.m.      Coffee Break

10:45 a.m.      Jeff Polovina
11:00 a.m.      James Bohnsack
11:15 a.m.      Norbert Simmons
11:30 a.m.      Arthur Lyons
11:45 a.m.      M. Ben-Yami

12:00-13:30      Lunch – RSMAS
13:30 p.m.      Edward Lipuma
13:45 p.m.      Timothy Visel
14:00 p.m.      Walter Adey
14:15 p.m.      Judith Hansen
14:30 p.m.       Jim McVey
14:45 p.m.      Frank Williams
15:00 p.m.      Coffee Break
15:15 p.m.      Don McCreight
15:30 p.m.      John Kubaryk
15:45 p.m.      Sarah Meltzoff



Appendix #2

Innovative Marine Technologies
General Chapter Outline

Introductory –
      Relevant historic background.
      Highlights and importance of topics covered.

Discussions –
Description of specific techniques, processes or equipment including benefits and possible areas of use.
Case histories, if available.
Products or techniques in development.
Other possible applications.

Limitations –
Anticipated problems (including health, safety, environmental, social) in use of new techniques and products.

Research Needs –
Work required to expand application of described techniques or bring those in development to fruition.

Research Contacts –
Names and addresses of active researchers in the areas described who may be willing to provide readers with further information.

Selected Readings –
      Significant reviews and general books and articles.

Subcommittees
I.   Socio-bioeconomics            IV.    Boats
Frank Williams                  Edward Harper
Sarah Meltzoff                  John Sainsbury
Edward Lipuma                  John Shortall
                        M. Ben-Yami

II.   Gear and Equipment            V.    Artificial Reefs
Arthur Lyons                  Jeff Polovina
M. Ben-Yami                  James Bohnseck
Steve Drew                  Jim McVey
Norbert Simmons               William Alevizon
Tim Visel

III.   Coastal Mariculture            VI.   Fish Preservation
Walter Adey                  Dom McCreight
Judith Hansen                  John Kubaryk
John Kubaryk                  Norbert Simmons
Jim McVey
Tim Visel                  VII.   Alternate Energy Sources
                        Steve Drew
                        John Sainsbury               
Appendix #3
NATIONAL RESEARCH COUNCIL
OFFICE OF INTERNATIONAL AFFAIRS
2101 Constitution Avenue    Washington, DC 20418    USA


            

2 August 1985

Timothy Visel
Sea Grant/Marine Advisory Service
UConn, Avery Point (Bldg. 24)
Groton, CT 06340

Dear Tim,

   Since there are less than two weeks before our Miami meeting concerning appropriate technologies for artisanal fishermen in the Third World, I wanted to inform you of the latest developments.

   A final program for the meeting is included, as is a list of participants.  I feel that we have a well-rounded group of highly qualified people.

   Your presentation on Wednesday need not be formal.  It is for our "internal consumption" and will not be published.  If you would like to distribute copies, excellent, if not, that is acceptable.

   We are more interested in exchanging ideas on innovations that could help small-scale fisheries.  Please bring materials, reprints, bibliographies, names and address of research contacts, and photographs which will help us write the manuscript.  We hope that you will be prepared to discuss research needs and the limitations of the technologies, as well.

   Included is an NAS travel voucher, so that you can begin to record your expenses.  Please save all receipts.

   Have a good trip to Miami.  We'll see each other on Tuesday!

                     Sincerely,
                     Daniel
                     Daniel O. Suman
NRC Fellow


Appendix #4
THE UNIVERSITY OF CONNECTICUT
COOPERATIVE EXTENSION SERVICE
SEA GRANT MARINE ADVISORY PROGRAM
Avery Point Campus, Groton, CT 06340   Telephone: (203) 445-XXXX or 446-XXXX, Ext. 234

February 12, 1986

TO:      Norm Bender, Program Leader
FROM:   Tim
SUBJECT:   pH Meter and Field Demonstration Projects

   I recently met with Dr. Gary Griffen (UConn Soil Testing Laboratory) concerning marine soils and pH testing equipment.  Gary loaned me two texts, one on soil chemical analysis and one on eutrophication.  He also provided me with two pH meter descriptions that he thought would satisfy some of the projects outlined in my memo "Shellfish Aquaculture Development Programs for Connecticut" – December, 1985.
   I feel that we should go with the Model 107 pH meter at a cost of $210.00.  Gary felt it would be sufficient also.  Perhaps if there is extra registration money left after purchase of workshop materials, it may be put towards purchase.
   What do you think?


TCM: em
Encl.

Appendix #5
THE UNIVERSITY OF CONNECTICUT
COOPERATIVE EXTENSION SERVICE
SEA GRANT MARINE ADVISORY PROGRAM
Avery Point Campus, Groton, CT 06340   Telephone: (203) 445-XXXX or 446-XXXX, Ext. 234


March 23, 1987
Mr. John Scillieri
26 Sea Breeze Drive
Waterford, CT 06385

Dear John:
   I have enclosed the information you requested on clam management and restoration of marine habitats.  I have completed several restoration programs for seed oyster beds and noticed that small and adult flounder soon return.
   In addition, we now realize how important it is to cultivate marine soils in order to get good sets of clams.  I presented a paper a year ago August for the Board of Science and Technology of the National Academy of Science on this topic.  It should be printed this summer and I will be sure to forward a copy to you.
   I'm sorry you won't be able to make the Forum but I look forward to meeting with you soon.

                     Sincerely yours,

                     Timothy C. Visel
                     Regional Marine Extension Specialist
                     Fisheries/Aquaculture

TCV/doc
Enc.


Appendix #6

Yankee Magazine, October 1974
Reprinted with permission Judson D. Hale, Editor
Aquaculture and the Man with the Blue Thumb
By Stephen C. Altschuler

When Rev. Richard W. Burton went to Scituate, Massachusetts, hearing to seek permission to raise and harvest soft-shell clams in the tidal flats of the North River, he was startled at the response to his aquaculture proposal. 

   "Before the hearing started," the West Bridgewater minister and Brockton High School oceanography teacher told me, "one woman in the back of the room got up and said, "I don't know what they want to do but I'm against it anyway."  Then another man said, "So am I."

   Reverend Burton, who has been a marine biologist for about 25 years, believes New England realizes only a small fraction of its marine fishery potential.  As a former government biologist, he saw "billions spent in research" and a vast amount of knowledge accumulated, "but it bothered me at the end of a year you'd think over what you accomplished – and you learned a lot – but you couldn't point to one solitary clam or oyster that was there because you helped it get there."  There are some exceptions, but present aquaculture efforts in this area are generally piecemeal and provincial.

   After designing and building some equipment from discarded scrap metal, he received some generous volunteer help from the U.S. Coast Guard, and eventually produced a good number of healthy clam sets on a flat that had been out of production for years.

Rev. Richard Burton, founder of Project Dominion, demonstrates his homemade cultivator. Seawater p
umped through the device agitates the surface of an ecologically stagnant clam flat and adds oxygen and nutrients – resulting in a healthy set of clams.   
Reprinted with permission from the October, 1974 issue of Yankee Magazine, published by Yankee Publishing, Incorporated, Dublin, NH 03444.

Appendix #7
Barnstable County
Cooperative Extension Service
COLLEGE OF FOOD AND NATURAL RESOURCES
University of Massachusetts and U.S. Department of Agriculture Cooperating




Cape Cod Extension Service
Deeds and Probate Building
Railroad Avenue
Barnstable, Massachusetts 02630

October 10, 1985

Tim Visel
Connecticut Marine Advisory Service
University of Connecticut
Avery Point
Groton, CT 06340

Dear Tim,

   Thank you for participating in our December 3 conference on coastal pollution and shellfisheries.  Some conference objectives are in identifying some of the current trends in Massachusetts (!) and providing some solutions via programs currently in effect in other states.  I have titled your talk "Regeneration of Non-productive Bottom," and scheduled it for 1 pm.  I will be sending you a flyer on the conference soon.

   If you have any questions, let me know.

Sincerely,
Karl
Karl Rask
Regional Marine Extension Specialist

Appendix #8

Proceedings of the National Shellfisheries Association
Volume 57 – June 1967

FACTORS AFFECTING THE RELATIVE ABUNDANCE OF MERCENARIA MERCENARIA IN THE PROVIDENCE RIVER, RHODE ISLAND

S. B. Saila, J. M. Flowers, and M. T. Cannario

MARINE EXPERIMENT STATION
UNIVERSITY OF RHODE ISLAND
KINGSTON, RHODE ISLAND
and
RHODE ISLAND DIVISION OF CONSERVATION
WOCKFORD, RHODE ISLAND



ABSTRACT

A simultaneous examination of sediment properties which included particle size, pH, cation exchange capacity, organic carbon, total nitrogen, available phosphorus, and water depth was made in an effort to discriminate between two classes of bottom sample in the Providence River.  Once class contained relatively large numbers of Mercenaria mercenaria and the other had a low abundance.  The linear discriminant function was found to be significant utilizing the eight measured variables.  However, it was found that only two variables, organic carbon and particle size greater than 2 mm diameter, effectively contributed to the discrimination of the two levels of abundance.

INTRODUCTION

Data from sampling surveys as well as information from catch statistics have clearly demonstrated that the hard clam or quahog, Mercenaria mercenaria L., is a resource or major economic importance in Rhode Island.  During recent years, its annual value to local fishermen has approximated one million dollars.  Annual yield during this time have been in the vicinity of 200,000 bushels.  Pratt (1953) has shown that the hard clam is the most abundant animal of its size living in or on the bottom, and that it constitutes a significant portion of the total bottom-dwelling community in Narragansett Bay.

Pratt (1953) demonstrated that hard clams grow faster in sand than in mud when other variables are eliminated but also indicated a high level of abundance in fine sediments with larger particles such as shell and rock as minor constituents.  The significance of particle size greater than 2 mm (variable 2) was clearly demonstrated in this analysis, and supports the previously completed growth comparisons mentioned above.  Pratt and Campbell (1956) in summarizing observations on environmental factors controlling growth of the hard clam in Narragansett Bay stated that growth was not appreciably influenced by existing differences in current speed, dissolved oxygen content or the salinity of the bottom waters.

CONCLUSIONS

Since exploitation appeared to be relatively low and the sampling gear has been previously demonstrated to be efficient, it is reasonable to conclude that the observed differences in the abundance of hard clams in the sampling units were real.  This indicates that the distribution of the clam was not uniform but instead showed aggregation.  When the samples were partitioned into two groups (high and low abundance), it was found that only the organic carbon content of the sediment and particle size greater than 2 mm diameter contributed significantly to the separation of the samples in the two abundance classes.


Appendix #9

The Day, New London, Conn., Wednesday, June 12, 1985

Specialist Warns Agency of "Black Mayonnaise" Threat
By William Hanrahan
Day Staff Writer

GROTON – they call it black mayonnaise – it's the murk and muck, sometimes several feet deep that collects on river bottoms.  It's also the stuff stifling the area's oyster crops, according to an expert.
Addressing the town's Shellfish Commission Tuesday night, Timothy C. Visel, a marine resource specialist for the University of Connecticut, said the build-up of debris in shellfish areas can weaken or eliminate growth.
Working in waters off Old Saybrook, Clinton and Madison, Visel said production of oysters there has more than quadrupled thanks to clean-up efforts during the past three years.

"There seems to be a trend that our rivers are filling up with black mayonnaise," he said. "We have seen a dramatic increase in river life as the dead stuff is removed."

The accumulation of debris occurs in waters with poor circulation. "We get so many nutrients going into these sluggish coves without a lot of circulation," Visel said.  "This causes a build-up and no oxygen gets down in the water."

Visel said removing debris not only enhances oyster growth, but has increased the presence of a number of other fish, including flounder.
Visel said Connecticut used to be a leader in oystering about 100 years ago, with local areas such as the Poquonnock River as prominent beds. More than 100 oyster companies on Cape Cod used to rely on seed oysters from Connecticut which were brought there to mature.
Production dwindled to almost nothing as waters became polluted, he said.  A clean water act in the late 1960's helped rekindle the industry during the 1970's, but things are still not what they used to be.

Removing black mayonnaise helps oysters and other life forms grow and even cultivate in areas previously devoid of life.
"About 1500 bushels came out of Old Saybrook last year and no shells were put in the water," he said.
Visel said areas where mud is a problem often smell bad or show a white, milky substance floating on the water.  Commission members said they had seen signs of this in town waters.

Debris can be removed from river and cove bottoms with oyster dredges, Visel said.  By stirring up the mud at high tide, the debris is able to flow out of the area when the tide changes.