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Do We Have the Correct Scallop Grass? 1931-2011 – IMEP #29
EPA – DEEP Long Island Sound Study Citizens Advisory
Committee Meeting
CAC Meeting September 13, 2012
The Profound Habitat Reversals for Long Island Sound Fisheries
Postponed from June 14, 2012 – Joint Meeting CAC – STAC Meeting*

--My View--

Timothy C. Visel
Morrison Foerster Law Firm
1290 Avenue of the Americas, New York, NY
Revised to July 1st 2013
For New England Shellfish Commissions
Updated for Capstone Projects, January 2014
IMEP Newsletter#29, October 2014

Habitat Information For Fishers and Fishery Area Managers
Understanding Science Through History
(IMEP Habitat History Newsletters can be found indexed by date on
The Blue Crab.Info™ website: Fishing, eeling and oystering thread
And Connecticut Fish Talk.com Salt Water Reports)
A Capstone Proposal – Case History Discussions Leaves and Brown Waters Hurricane Irene Tropical Storm Lee
September 2014
Timothy C. Visel, Capstone Proposal Series The Sound School
60 South Water Street
New Haven, CT 06519

Abstract
Since our last warming period began in earnest about 1973-74, Long Island Sound and its fisheries have greatly changed. As habitats transitioned, resource productivity on a species level has also changed. Species whose habitats are sustained or created by colder energy filled periods such as bay scallops, and winter flounder have declined greatly while those who benefit from relatively low energy and periods of heat, namely oysters and black sea bass have increased. The overall productivity from Long Island Sound however, has basically remained unchanged for almost two centuries. As colder species declined from habitat failures (lobsters, hard clams and bay scallops) they were matched by increases in soft shell clams, oysters and blue crabs as their habitats improved. The blue crab explosion of the past decade is an excellent example of such habitat population reversals. But Long Island Sound has seen such climate related habitat reversals several times before and this current four decades long hot and relatively storm free period is similar to a period that occurred here before – called The Great Heat (or “hot” term if you lived north of Rhode Island) a period of approximately four decade between 1880-1920 in which summers became increasingly hot and shore communities grew quickly next to stable coastlines absent very strong storms. This was a stark transition from the 1870s a period in which many surmised a possible return of The Ice Age. In 1874-75 it got so cold (30° below Fahrenheit), most of the apple orchards in Connecticut were destroyed – barns were now connected to farmhouses and waterfowl grew scarce in harsh winters. The coastal storms of the 1870s and numerous shipwreck sinking’s and port damage give rise to the federal effort of the 1890s to build stone breakwaters along Connecticut’s coast. The Great Heat was to change all of the above.
Some of the fisheries impacts of The Great Heat caused a tremendous increase in soft clam sets, followed by very strong oyster sets ending with a surprising surge of blue crabs. In southern New England even extending up into Buzzard’s Bay then became significant producers of the blue crab. What also occurred during the same period was a failure of the Southern New England lobster fishery, the collapse of the New York, Connecticut and Rhode Island Bay Scallop Fisheries, and after hard clam set failures Quahogs now became very scarce. The last large quahog bed off Nantucket failed in 1915. Good hard clam sets did not return to Connecticut until 1931-38. Winter flounder fish kills (high heat/sulfur toxicity) were most severe in New York, Long Island bays and harbors. One particularly severe winter flounder fish kill occurred in Moriches Bay, July 29 to August 4, 1917. Water clarity declined and marshes were known to produce “toxic” stinks (sulfide gases) on hot summer nights along Connecticut’s shore in summer. If this sounds familiar it should; it mirrors many Long Island Sound Habitat conditions today; almost precisely.
Problem Statement – The “Trouble” with Eelgrass
Although many recent articles discuss the positive attributes of eelgrass to shellfish sets any such setting capacity is soon lost in high heat and low pH levels from the marine soils in which eelgrass grows. During the recent high heat low energy period (1974-2004) eelgrass trapped organic matter that is reduced in low oxygen (warm water) to produce acidic low pH bottoms. This condition is lethal to bivalves even bay scallops*. In colder water bay scallops will set up upon red algae, (thought now to be preferred) shells and clean sand even pebbles, in warmer water desiring to be off the bottom from sulfur toxic and acidic conditions scallop will set on ropes, tree branches, lobster pots anything including eelgrass. Research articles from overseas now mention red algae producing Mearl as the preferred scallop habitats. Sapropel is a jelly like black to grey organic marine humus (compost). In low heat it contains a sulfur reduction process and as it rots it creates organic acids and sheds ammonia a plant nutrient that favors harmful algae blooms (HABS). Fishers call it black mayonnaise a rotten egg smelling hydrogen sulfide material that collects on bay bottoms during periods of high heat and low energy conditions. It is so acidic it will stain hands black. It has in some embayments become a dominant habitat type and very damaging to both winter flounder and bivalves but Sapropel is rarely if ever mentioned at all in numerous eelgrass habitat reports. Eelgrass meadows naturally trap leaves and organic matter and create some of the first Sapropel deposits, as it lowers pH to below bivalve lethal limits. Few eelgrass studies mention the pH of the marine soil below eelgrass meadows in high heat as it is so acidic and often deadly to shellfish sets. As it collects sulfate reduction tends to make it alkaline without oxygen. But when oxygen is reintroduced it not becomes very acidic.
It‘s natural that eelgrass in high heat low energy conditions to lower pH in marine soils and extensive pH soil sediment discussions are very much absent from many eelgrass papers. As shellfishers have long known pH is key to good growth (similar to land) and acidic or “sour bottoms” (without shellhash) have been known to be poor shellfishing areas. What can help bivalve sets and eelgrass is in fact energy – bottom disturbance – soil cultivation shellfishers for hundreds of years have talked about the benefits of hard raking and “working the bottom” this introduces basic “sweet” seawater (high pH) into marine soils freeing it of organic acids*. It also raises “blank” shell buried in sediments to the surface helping to modify low pH bottoms. The observations of fishers with soil cultivation are essentially correct as some of the largest bivalve sets, for clams happen after “new sand” from storms are free of acid or after barrier beach breaks. When quahoging in Rhode Island ago bullrakers learned that even small cultivation impacts could raise pH and would seek out areas of mooring chains – sweep, just the rolling of mooring chain over the bottom was enough to cultivate the marine soils to keep pH from lowering to toxic levels for clam sets (personal observations also).
Coastal energy (storms) and cooler temperatures helps both quahogs and bay scallops. It also helps thin out dense compacted eelgrass roots (like thinning carrots) so after coastal storms eelgrass populations can return from the “slimy/furry” eelgrass to the loose sand clean and green eelgrass. Bottom disturbance even dredging can help eelgrass by creating loose acid free soils in which it can grow quickly. Ironically many eelgrass publications/reports list bottom disturbance as a negative factor – short term it is (see thinning carrots) but the densest eelgrass meadows historically occur after periods of cold stormy periods and it is part of a massive habitat transition. High heat and low energy actually helps eelgrass habitats fail faster and then die off and give rise to Sapropel a dominant habitat type that is rarely mentioned in today’s current eelgrass studies. Fishers recognized it; it’s often called black mayonnaise. Such deposits are acidic and deadly to bivalve sets. Quahogers on Cape Cod would often find immense sets of hard clams under eelgrass held Sapropel which all suffocated (Ron Ribb, personal communication – Tim Visel 1982) Connecticut oyster growers a century ago found that the placement of oyster shell for spat falls (thin layers) resulted in huge sets of quahogs below them and determined that shell like lime on land had moderated pH. David Belding a noted shellfish researcher on Cape Cod mentioned similar tests with marine soils a century ago. The pH of marine soils is a critical habitat quality area that seems to be overlooked in nearly all recent eelgrass studies.
Climate and Energy Govern Eelgrass and Bay Scallop Populations
Eelgrass did have population changes also and we have had four habitat reversals since 1860 to follow eelgrass patterns. The colder and stormier period of the 1870s saw bay scallops surge but this constant energy and cold tended to keep eelgrass populations to very low levels; as the warming period commenced eelgrass populations surged, but bay scallop production collapsed and as the densest eelgrass meadows formed, scallop habitat quality further declined. In some coastal communities bay scallops disappeared altogether. Eelgrass in some bays and coves became a nuisance to bathers and boaters, and in dense populations collapsed tidal exchange. In high heat it rotted in oxygen depleted waters creating hydrogen sulfide toxic events. Sulfurous gases caused by rotting eelgrass were termed a public health hazard in Groton CT in the late 1880s. Massachusetts communities hired horse teams to clear eelgrass from Revere beaches. As soon as 1882, New York was hiring people to mow eelgrass in coastal ponds, and a business developed (Cabot Corporation) to harvest “excess” eelgrass for 50 years to be made into home batt insulation (the first). Fishermen that harvested eelgrass were known as “Cabot’s cutters.” But waterfowl especially Brant loved the eelgrass and warmer weather encouraged geese to winter over here and coastal salt marsh hunters were delighted to find a huge increase in game birds. Areas that had been free of eelgrass such as the deep water bay scallop beds in Narragansett Bay in the 1880s had sea grasses cover previous habitats changing the habitat quality for bay scallops. By 1905 bay scallops were gone as eelgrass meadows grew thicker and deeper extending north far beyond the Long Island Sound. As eelgrass meadows spread throughout Narragansett Bay the cold water high energy habitats failed for bay scallops. Eelgrass meadows then suffocated bivalve species and in high heat altered the pH of marine soils. New England bay scallop fisheries “collapsed.” Excellent write ups can be found in the reports of the Rhode Island Shellfish Commissioners during this period.
The Habitat Reversal 1931 to 1951
In the late 1920s temperature and energy conditions changed and 1931 saw energy levels increase as temperatures fell. A habitat reversal was happening- dense eelgrass meadows infected with a mold now wasted away and became scarce. The 1940s and 1950s, as winters became colder and frequent storms became more severe, bay scallop habitats improved. Without eelgrass the Connecticut Niantic Bay scallop fishery soared. This also occurred in other bay scallop producing areas as well. Coastal erosion and seawall damage was extreme in the 1950s and 1960s. Many people will remember the 1950s and 1960s for the number of strong hurricanes. However bay scallops thrived in this high energy period. The bay scallop sets seemed to improve after every hurricane in Niantic Bay without much eelgrass. Marine soils washed of organic acids, now contained huge sets of hard shell clams. Some of the largest hard clam sets occurred in or near abandoned oyster beds (shellhash). By the middle 1970s storm activity dropped as energy levels declined and temperatures increased wide spread hard shell clam sets diminished. As aspect of the pH in soil and the decline of eelgrass is now linked by accumulated organic debris and the sulfur cycle.
Habitat Reversal 1972-1992
After 1972 the NAO climate pattern moderated to New England winters became progressively mild and energy storm intensity declined. Eelgrass started to decline in Europe. First in France and resembles the current eelgrass cycle. Organic matter from land started to accumulate faster on eelgrass meadows (eelgrass in 1931 died off worldwide from slime mold disease) mostly leaves and manure a century ago. Eelgrass can hold terrestrial organic matter between blades and such eelgrass meadows between 1880 – 1920 that will rise over time sealing the oxygen bacterial process from oxygen limited sulfur bacteria below. High temperatures in the 1890s was thought now to create vast deep water eelgrass meadows reported by Nichols just at the turn of the century. AT the same time sulfate digestion rose to the top of some salt marshes and bacteria consumed stored organic matter.
It can be argued that eelgrass was already beyond its habitat clock by 1920 and that populations after 1920-1925 can be considered a monoculture legacy from organic free estuarine bottoms four decades before. As organic matter below eelgrass continued to rot it created a disease medium for a monoculture worldwide pandemic, which started in Europe in the 1920s. Monocultures are vulnerable to such disease outbreaks as current aquaculture and agriculture industries can attest. 1931 is the year that the cyclic pandemic became worldwide and many weakened eelgrass meadows from exposure to the sulfur cycle (root damage) left them vulnerable to disease and strong storms (energy). Sulfide levels under eelgrass meadows are high from sulfate reducing bacteria, which thrive below them. This affects the root health of eelgrass and strong storms tend to destroy such meadows and release Sapropel deposits under them. It is now evident that eelgrass in our region is susceptible to terrestrial organic inputs (mostly leaves) and that organic matter can sustain disease-causing bacteria. Sulfide and aluminum levels are high beneath spartina meadows in coastal marshes for much of the same reason – sulfide-reducing bacteria.
The natural cycle of eelgrass is part of the sulfur cycle, which can create habitat reversals in our estuaries over long time periods. These events have been captured as evidence of coastal cores which portray organic layers between layers of sandy / shell layers. The habitat value over time greatly changes for eelgrass as it first occupies cultivated low organic soils / high sand good soil porosity and dies in soils that contain waxes high sulfides and general low soil porosity. Some eelgrass replanting experiments have failed because they were planted in composting deposits called black mayonnaise, which can have high sulfide levels if it then becomes reduced to Sapropel.
By 1992 eelgrass succumbed to a second disease die-off that was very similar to the 1931 – 1951 reversal
Mixed Eelgrass Habitat Values
In 1979 while working at the University of Rhode Island Department of Fisheries, I had the opportunity to bay scallop in Point Judith Pond; 1978 was a cold energy filled period (The Blizzard of 1978). Bay scalloping in Point Judith was very good the following year but arguments soon developed between older scallopers and those –well, let’s just say younger fishers that avoided eelgrass beds and those who persisted in dredging through the middle of them. A couple of us challenged some scallopers about that, and while we were the younger ones, we felt that eelgrass was important to bay scallops ecology: that is what we had read and learned at school. Those more senior scallopers set dredges to purposely rip it out and told us it (eelgrass) was not good for scallops. I felt at the time they were very wrong, I no longer feel that way. It was while I was working for the University of Rhode Island I heard my first direct account of sea grass damage to bay scalloping in Narragansett Bay at the turn of the century.
In the late 1970s, I attended some New York fishermen forums to speak about inshore fishing gear but was soon surrounded by fishers that were concerned about Peconic and Great South Bay – grasses and organic matter was ruining bay scallop and winter flounder habitats. The bay bottoms there once clear and firm now they were turning soft and foul smelling giving rise to the term “sour bottoms.” I would listen to repeated accounts from Long Island Sound Baymen for over two hours – the decline of “good bottoms” where winter flounder once thrived.
By 1981, I found myself on Pleasant Bay on Cape Cod and living in Chatham working for the University of Massachusetts; here I found more shell fishermen who told more stories about eelgrass overrunning and ruining hard shell clam beds, oysters and even bay scallop habitats, but this time it was different, they had federal reports from the Army Corps of Engineers and other older Massachusetts reports that also mentioned the same thing, and not just for Cape Cod, but most of the areas to the south to the Rhode Island border.
By 1984 my views towards eelgrass were changing and while at UCONN Sea Grant, as more and more Niantic Bay Connecticut fishermen described the damaging impacts of eelgrass populations, I began to question the value of eelgrass habitat and possible damaging impacts of eelgrass populations. These accounts did not fit those commonly accepted habitat associations or bulletins printed for the public at the time but were very similar to those mentioned by Rhode Island, Cape Cod and now Niantic Bay Connecticut shell fishermen. I wrote up an account for the Niantic Bay eelgrass fisher experience in part for Dr. Sheila Stiles of the NOAA, Milford Laboratory in 2007. It is on our adult education website http://www.soundschool.com/directory.html as paper #25, Bay Scallop Genetics and Transplant Programs to Niantic Bay, 1916 to 1935: An Historical Account (March 2007). In the next three years I would research the habitat history of several species including eelgrass beginning in earnest in 2008 as interest in it increased as a possible indicator species for estuarine health related to natural cycles.
Uncertain Habitat Values – An Incomplete Habitat History
For eelgrass it is not a great habitat history story, in fact the habitat value of eelgrass overall is highly mixed. In colder times in loose sandy bottoms I find reference to positive structural (artificial reef) and feeding habitats for many fish and crustaceous species including lobsters and blue crabs. But that is the “clean and green” patch eelgrass that is in cooler, well circulated tidal areas and relatively rare today1. The law of habitat succession comes in - these habitats get old and lacking energy to reinvigorate them they “age” in high heat with acidic leaves from land they often become sulfur containing composting habitats. Firm bottoms with slight eelgrass in low energy/high heat become soft, the eelgrass blades widen and become weak as it traps more organics that in high heat cause dense root systems themselves to fail. The sulfide soil level below eelgrass meadows becomes so high the roots rot and the plant actually drifts away. This is the brown and furry eelgrass of many coves and bays. In time these monocultures fall victim to molds and fungus infections and perish as in the 1930s as they “waste” away.
Eelgrasses over such areas have high hydrogen sulfide smells beneath them and they tend to raise flat elevations below which often contain buried bivalve sets. It is in the eelgrass meadow in which the first Sapropel deposits are formed.
After a cold and stormy period eelgrass has a very different habitat story, it quickly colonizes recently disturbed marine soils, similar to the invasive terrestrial plant phragmites. Its reproductive and growth capacity over time out competes other species as its blades slow currents and traps sediments; it can and does create its own habitat. Shellfish species that may have set first into these recently recultivated marine soils are gradually buried and then suffocated. As the monoculture spreads and heat intensifies previously alkaline bottoms gradually become acidic, unstable to the bivalve setting and growth and hostile to fish such as winter flounder. The combination of eelgrass and low pH displaces red algae now shown to be a significant scallop habitat type. Additional research is now linking eelgrass growths to fin rot disease in winter flounder (Saprolegnia). If extremely thick, eelgrass may reduce embayment circulation; add to stagnation of marine soils accelerating acidification and in high heat, oxygen depletion. At this point it starts to end its own habitat clock as high heat die off occurs as it did worldwide in 1931 following four decades of enormous growth. This happened in other countries as well as the United States, it dies off. Dense monocultures are subject to widespread disease outbreaks and eelgrass is no different.
Shellfish regulators researchers and often biologists noticed this succession tendency decades ago and it became a scourge rather than a welcomed guest. As John Clint Hammond, a retired oyster grower on Cape Cod said something to the effect that it’s “like a house guest that visits and decides to take over your house.” Numerous articles and attempts to control eelgrass occurring in all the shellfisheries even bay scallops during the 1950s and 1960s included esters of 2, 4, 5-T thought to be herbicide Agent Orange (Cape Cod Experiments).
The methods and attempts to control eelgrass growths are numerous and lengthy and documented in other reports. One has to take into account what people saw and experienced and recorded rather than repeat much of the same information again2. Quite simply eelgrass would come into productive soft shell and quahog habitats and kill them.
One of the things I have discovered in conducting this limited research for eelgrass (habitat history) is that it likes bottom disturbances (energy), and dredging might be the only way it can recover. I would look at recent dredging projects as cleaning deep organics accumulated in the decades of increased terrestrial leaf deposits (oak and maple leaves are very acidic 3.4.3.6) and rot in high temperatures causing eelgrass roots to weaken. A cleaned and energized marine soils (increased tidal flow) would create better habitat conditions for eelgrass. Deep soft, thick eelgrass meadows in Clinton, Chatham, Pleasant Bay and Niantic Connecticut frequently had buried shellfish below them. That is the eelgrass habitat history in many areas as it traps sediments and raises reliefs. There is a write up of an attempt to improve bay scallop habitat on Martha’s Vineyard by dredging. The deeper dredged section had many more bay scallops than the shallows (NOAA reference, Clyde Mackenzie).
Summary
While many recent publications highlight the value of eelgrass as a key indicator of estuarine health, long term records show otherwise. It is a much better indicator of habitat succession and a needed effort to include climate and energy cycles in estuarine studies. In high heat and low energy periods as the pattern progresses (or habitat succeeds) eelgrass at first grows thick and then dies off – this appears to be a worldwide natural cycle repeated several times since 1850. Estuarine core and sediment pH studies are needed to be included in current eelgrass studies especially its relationship to winter flounder and bay scallops which often have on negative (inverse) abundance relationship – not positive. Shellfishers and shellfish researchers recorded this habitat successional attributes of eelgrass and the negative impacts of eelgrass upon shellfish resources even bay scallops a century ago and again in the 1960s. These reports now appear to be “forgotten” in the current literature but we need a full habitat review of all these sources – especially in relation to the bay scallop.
While few studies mention it, marine habitat succession is real; it exists but takes much longer to see. If you stopped cutting a residential lawn (energy input) in two years a passerby could easily see the habitat succession in the marine environment that same view takes 25 years. Any “pictures” less than 50 years give viewers a snap shot that has the bias of time and not the completed habitat succession movie which could be a century to record. Environmental fisheries history is a critical area for investigation. As far as eelgrass we really don’t have a complete habitat history.
Addendum September 12, 2012
I would like to summarize my comments by including a short report I submitted to the Habitat Restoration Work Group on September 10, 2012 following our September 5 meeting. It details some of the concerns around eelgrass and the need to fully review the impacts from energy and temperature upon Long Island Sound habitats and the fisheries they sustain.
Thank you.
Tim Visel

Addendum – October 2014
Since the outline of the first paper of eelgrass/bay scallops habitat association in 2007 other research implications have been raised. Today several researchers are examining the North Atlantic Oscillation – for patterns of habitat change, several core studies in Connecticut estuarines (1992-1994) have been made public and research into Native American shell middens all indicate previous habitat types or reversals here with the past 800 years. A guiding factor in estuarine habitat restoration policy is climate factors – some of which appeared in the scientific literature a half century ago.

Interest in habitat modification/creation has increased tremendously since Hurricanes Irene and Sandy. Efforts continue to bring temperature and energy patterns into public policy discussion as they did in the 1950s and 1960s with federal flood and erosion control legislation. The 1950s and 1960s was a cooler and energy filled period for Connecticut, it was also a negative NAO (climate) period. We can learn from past habitat patterns as we prepare for future restoration efforts. Shellfishers have long known that periodic cultivation of oyster lots (beds) tends to reduce leaf accumulations and prevented the accumulation of Black Mayonnaise which under low oxygen conditions (high heat low energy) becomes Sapropelic.

Capstone questions – This research are also appears to be under students interested in researching the eelgrass/bay scallop habitat association should research the Mearl producing coralline red algae worldwide. Many publications are on the internet now and readily accessible, the best one available is The Settlement of Cues of an Articulated Coralline Alga Marginisporum crassissima for the Japanese Top Shell Turbo cornutus. JSR28 (3) pg 5 69-575. This article lists another 30 references. After reviewing this publication do you feel we have the correct scallop grass?

Appendix 2 – Do We Have The Correct Scallop Grass?

Page 6 February 10, 1983 VILLAGE ADVERTISER

EDITORIAL

TOO MUCH EELGRASS? “Working Bay Bottoms”

I was pleased to read Mr. Nawoichik’s letter in the February 3rd edition of the Village Advertiser commenting on Mr. Dow’s January 20th article about shellfishing. One thing was mentioned in both the articles regarding how beneficial eelgrass is in our bays. I wonder how many studies have been done on eelgrass, codium and other grasses when they become over abundant.

In the Hyannis bays, the over abundance is more than obvious by the huge windrows piled high on the beaches, the nuisance caused by blocked marsh ditches as well as the considerable expense to the town to remove it each year.

If great amounts of eelgrass are the criteria for good crops of shellfish, then certainly this area should produce extremely well each year. Just the opposite is the case and it appears that other towns up Cape from Barnstable are experiencing the same effects. In some of the bays, the eelgrass and codium are slime and silt covered, greatly reducing the flow of nutrients to the shellfish. This silt laden mess is certainly not preferred as a setting place for shellfish as they leave the veliger stage. When the roots finally get so thick that they crowd one another out, the losers decay; and with no oxygen in the soil create gases that shellfish cannot live in.

I have glassed the bays on the south side of the Barnstable for a third of a century and when I started, there was very little eelgrass, no codium, and small amounts of floating grasses. We had a good crop of scallops each year, were allowed a bushel of oysters per week on our family permit as well as a peck of clams and quahogs. As the grasses closed in, silting became much more noticeable. The oysters had no place to set except on the stones, shells or grass at the shore’s edge and this area is periodically blasted by severe winter weather and most oysters are frozen and lost. Finding very few areas to set, scallops have greatly diminished in numbers and are found in small places where the bay floor is grass free. I would assume that the grasses will again get a blight as they did in the nineties and twenties and a more balanced shellfish situation will return.

During the late 1920’s and all through the 30’s, there were unbelievable amounts of shellfish and finfish in our bays. This was a period of practically non-existent eelgrass. I realized that weather conditions during that period were the reasons for such unusual shell fishing because the predators were greatly reduced but also the bay floors were clean, creating a fine environment for shellfish and finfish to live on and in.

It is time to talk facts about our bays, their potentials and the wise use of them. There can be a very good shellfish resource there and with cooperation from the shellfishermen, users of the waterway, and the shore owners, this could be accomplished. The shellfishermen, by continually working the bay bottoms, prepare the soil for future crops by realizing predators’ eggs and destroying predators living there. With some help from Mother Nature in the eventual reduction of grasses and some work by the shellfish department when the time presents itself, all could enjoy much better fishing.

John B. Farrington
50 Fire Station Road, Osterville.

THE COMMONWEALTH OF MASSACHUSETTS

Department of Natural Resources

BOARD OF NATURAL RESOURCES

Thomas a. Fulham, Chairman

William S. Brewster Joseph W. Lord
Frederick G. Crane, Jr. Arnold D. Rhodes
Robert L. Yasi
Commissioner

DIVISION OF MARINE FISHERIES

A Study of the Marine Resources of the Westport River is the seventh in a series of monographs initiated by the Division of Marine Fisheries in 1963. These reports relate the extent and value of the marine resources of the major bays and estuaries in Massachusetts. (Page 32)

The major factor limiting quahog abundance seems to be lack of favorable bottom. During the past decade eelgrass has been rapidly spreading on bottom areas which were formerly productive in quahogs. Quahogs sampled in eelgrass areas have reflected poor growth suggesting that the dense eelgrass interferes with circulation and food supply to the quahog. Soft bottom and dense eelgrass is especially obvious in the west branch of the river. The tendency toward less forceful ebb and flow of the tide in the west branch may be associated with hydrographic changes which have occurred with the gradual filling in of the lower harbor. Future dredging projects may bring about hydrographic changes which will favor the ecology of the quahog. (Page 31)

It has generally been acknowledged that current, or circulation is of major importance to the growth of the scallop, although certain studies in recent years (Cooper and Marshall, 1963) have suggested that current may not necessarily be the main factor accounting for the condition of the scallop. While no extensive sampling was conducted in the Westport River to compare the size of the scallops from areas of good and poor circulation, the shellfish officer and fishermen have reported that scallops growing on the flats among dense growths of eelgrass are considerable smaller in size than those growing on the adjacent relatively clean channel bottoms. On September 23, 1966 biologists made a survey of scallops occurring on an extensive shallow eelgrass flat in the west branch of the river. This sampling occurred about one week before the opening of the scallop fishing season. The average size (dorso-ventral height) of 60 scallops gathered in the area was 54.8mm, or about 2 3/16 inches. The “eyes” were notably small and not of commercial quality. Because of the small size of the scallops and the density of eelgrass in the area which hampers dredging, fishing during the scallop season was confined to the deeper areas further downstream in the estuary. (Page 31)

Eelgrass

Below mean low water, eelgrass (Zostera marina) is the most prevalent vascular plant growing in the Westport River. In recent years eelgrass has been rapidly spreading in the Westport River just as it has in other protected bays and estuaries of Southern Massachusetts. In moderate density, eelgrass is beneficial to many forms of marine animals. For instance, bait fishes and the juvenile forms of large species find shelter amidst the eelgrass clumps. Young bay scallops, upon reaching the setting stage, anchor themselves to the grass blades. Decomposing eelgrass forms detritus which is fed upon by many mollusks and crustaceans. (Page 43)

Detriment to shellfisheries also occurs when dead eelgrass accumulates in dense mats and smothers beds of shellfish. (Page 44)

Because of the increasing growth of eelgrass on shellfish beds, considerable research is presently being conducted to find an effective method of control. To date, no attempted methods have proven themselves completely practical. One town on the south shore of Massachusetts has attempted to cut eelgrass with an underwater mower designed for cutting submerged vegetation. At best, this method is only temporary since the plan stalk is cut off above the substrate surface leaving the stems and roots to produce new growth. Experimentation by various agencies with herbicides is presently being conducted. While certain chemicals such as 2, 4-D have effectively destroyed eelgrass, the toxicity of the chemicals to associated fauna is not clearly known. Similarly, it is still not known to what degree herbicide residues may accumulate in the live bodies of shellfish within and adjacent to the treatment are. Further investigation and analysis may pave the way for future practical and safe us of herbicides in the estuarine environment. Until such time, no herbicides should be introduced indiscriminately into our coastal bays and rivers. (Page 44)

An experimental attempt was made in 1961 to improve bottom conditions in areas void of shellfish by applying lime. Fifty-two tons of lime were spread over 12 acres of the river. During that same year fishermen were hired to dredge and remove starfish from the river. Similarly, dredges were used tin 1962 to thin out blue mussels which had become a problem by encroachment in mats upon valuable quahog producing bottom. (Page 30)
The blue claw crab is a species which were formerly abundant n the south shore of Massachusetts but has been declining in numbers for a t least the last decade. Such decline has also been observed in waters south of Massachusetts. Jeffries (1966) noted that the blue crab began to decline in Rhode Island in the mid-1930’s and that by 1938 they had diminished to the point that it was no longer profitable to fish for them commercially. The cause of the decline of this crab in our waters is unknown. Many fishermen along the shore have expressed the belief that the loss of blue claw crabs- also fiddler crabs (Uca spp.) is due to the careless use of pesticides in coastal areas. While it is certainly possible that pesticides have had a detrimental effect upon crab populations no conclusive evidence has been documented in this regards. (Page 39)