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(Placopecten magellanicus)    

Prepared by the
Gulf of Maine Aquarium
January 10, 2001

Table of Contents 





Our thanks to the many people who have made this project happen.  It would not have been undertaken without the commitment and vision of Linda Mercer, Director of the Bureau of Resource Management at the Maine Department of Marine Resources (DMR).  Her participation at every step of the way is an integral part of the final product.  Particular thanks go for her careful editing of the document.  Sue Inches, Director of Industry Development at DMR saw the opportunity to get funding and has provided support throughout.  Paul Anderson, Director of the Maine Sea Grant Marine Extension Program (MSGMEP), provided funding and his planning skills, took excellent notes, and generously contributed his staff.  The staff of DMR and MSGMEP helped in the planning and in making both the substance and the details of the meetings work.  Finally, without the fishermen and scientists who attended the meetings, this project would not have gone forward nor produced worthwhile results. 


Robin Alden
Don Perkins
Gulf of Maine Aquarium



I.  Background  

The sea scallop (Placopecten magellanicus) had a landed value of $­­­4.4 million in Maine in 1999.  The same year there were 741 boats with commercial scallop licenses and 353 scallop divers in Maine.   The state also licenses non-commercial draggers, and allows unlicensed, limited, non-commercial diving.

Scallops are managed by both the federal and state management agencies.  The federal scallop plan, which is developed by the New England Fishery Management Council and administered by National Marine Fisheries Service (NMFS), is predominantly an offshore plan that is focused on the large scallop resource and fishery on Georges Bank.  With minor exception, Maine boats no longer participate in the federal scallop fishery. Maine is unusual in New England because it has a viable inshore, small-boat scallop fishery, a significant portion of which occurs in state waters.  Of the 741 scallop license holders, only 32 vessels hold general scallop permits that allow them to harvest 400 pounds of scallops per trip outside state waters.  At most a couple of Maine scallopers hold limited access federal permits. 

The Maine scallop fishery is pursued by a variety of fishermen:  lobstermen fishing during the off-season, draggers who also fish for ocean quahogs and sea urchins, and divers who also dive for urchins.  Some groundfish draggers will rig for scallops if the abundance is great enough. 

Maine has retained the right to manage sea scallops within its state waters, despite the federal management.  State management has been limited to season, gear, and scallop size restrictions.  Scallops are a secondary fishery for most Maine fishermen, and the fishery has been managed principally to minimize gear conflict with the lobster industry.  For this reason, the season runs from December 1 to April 15.  Many management decisions continue to be made by the state legislature.  The Department of Marine Resources (DMR) has conducted limited scientific research and biological monitoring of the scallop fishery; however, a position has recently been assigned to focus on scallops and other fisheries in eastern Maine. 

Interest in scallop enhancement is the latest development in the fishery and is providing the impetus for far more research and experimentation.  Information about scallop enhancement techniques came as the result of a trip to Japan in May, 1998 organized by DMR and the Maine Aquaculture Innovation Center.  Fishermen along the coast are now experimenting with setting spat bags to collect spat for redistribution on scallop beds.  There is interest in using the same technique for grow-out in private aquaculture. 


II.  The DMR Research Priorities Project

This scallop research priorities were developed as part of a larger research agenda-setting effort conducted by the Maine Department of Marine Resources (DMR) for five of Maine's major commercial species:  clams, lobsters, scallops, sea urchins, and shrimp. 

Establishment of research priorities was identified during the late 1990’s as a key strategy to accomplish several of DMR's agency goals as well as the King Administration's 1996 Jobs from the Sea Initiative.  The ultimate purpose of the DMR research priority project is to ensure that fishery management decisions are based upon the best scientific and technical information so that Maine's marine resources are sustainable and productive.  The articulation of an agenda, however, will accomplish several other goals.  First, by establishing and communicating a shared vision of comprehensive research needs, it will stimulate the market for research that serves the state's needs.  Second, DMR will be able to direct internal funding decisions appropriately and identify and involve potential research partners from the broader marine science community, including the fisheries and aquaculture industries.  Third, the agenda should enable the entire marine science community to develop quick responses to outside funding opportunities on topics that serve the state's needs.

The project was conducted under contract by the Gulf of Maine Aquarium (GMA).  It was funded by a planning grant from the Economic Development Administration, the DMR, and the University of Maine Sea Grant Program.  The GMA consultants, DMR, and the University of Maine Marine Extension Team staffed the project. 


III.  Methodology

For each fishery, at least one, all-day meeting was held.  The meetings were designed to be non-regulatory, neutral, and inclusive following a format developed by the GMA in previous efforts for other species. The meetings brought together fishermen, academic scientists, government scientists, and fishery managers as equals.   They created an open  environment for curiosity and questioning.  Seven meetings were held on five fisheries to achieve broad input along the coast. 

Four topics were chosen for each species and scientists were invited to make short presentations on each of the topics.  In addition each of the presenters were asked to write a short analysis on some aspect of the topic or his/her research questions for the final report. 

Meetings ran from 9 a.m. to 5 p.m. with breaks and lunch provided.  Each day was divided into four sessions, each on a specific topic pertinent to the species.  Each of the four sessions had the same format.  First, the group spent ten or fifteen minutes brainstorming the questions they had about the resource.  Then the invited presenter gave a short presentation on a selected topic and his or her major research questions about the species.  After that, the group discussed the topic and the presentation, generating a list of questions that were summarized by one of the facilitators for later ranking.  At the end of the day, one half hour was spent in an informal ranking process where everyone was given 10 sticky notes to stick by the topics of their choice.  The day wrapped up with an oral evaluation and discussion of follow-up and ways to improve the process.

Publicity for the meetings was customized for each fishery.  Methods included direct mail to license holders, personal contact with association leaders, and posters distributed to sites in each town.  All of the meetings were covered in press releases to local and statewide papers.   


IV.  Scallop Research Priority Meeting

The scallop meeting was held May 16, 2000 at the University of Maine at Machias from 9 a.m. to 5 p.m.  Topics and presenters included:

1.  Assessment and Dan Schick, Maine Dept. of Marine Resources

     Current Management

2.  Biology/Oceanography Brian Bea, Ph.D., University of Maine at Machias 

3.  Enhancement  Richard Taylor, Gloucester, MA

4.  Gear  John Higgins, Darling Marine Center 

Forty-one people attended the scallop meeting.  Attendees included scallop draggers and divers, people involved in scallop enhancement, aquaculturists, DMR managers and biologists, a member of the Maine State Legislature, several consultants, a representative of The Nature Conservancy, and researchers from the University of Maine and the University of Maine at Machias.  


V.  Scallop Report Format

Results of the meeting are presented in two different formats: 

1. Priorities voted by the group (Section VI) which are presented with context; and

2. A detailed, categorized listing of questions, observations, and opinions articulated during the discussion (Section VII). 

The dual format is necessary in order to capture the richness of the meeting.  The priorities organize thought and focus effort.  The details are essential because it is the local observations and questions that provide the raw material of good scientific hypothesis.  Although the scallop meeting was divided into four segments:  Assessment and Current Management, Biology/Oceanography, Enhancement, and Gear, the report is not structured around those categories except where it makes sense.  Many topics, such as growth and reproduction, and oceanography were raised in several of the segments.  Therefore we have given precedence to the priorities articulated at the meeting rather than those used to organize the meeting.  Furthermore, we have not attempted to categorize the research questions by scientific discipline.  Under a given priority one might find questions for oceanographers, basic biologists, and economists or anthropologists.  The solutions to these problems require collaboration between disciplines and between science and industry.  The first step is to articulate the questions in such a way that researchers and industry are exposed to the question's rich context.

In every workshop there were questions and suggestions about management process and communication between fishermen, scientists, and managers.  We have included these observations and suggestions in the report.  We have not included specific suggestions for management measures because those fall outside the scope of this study.   


VI.  Priority Research Questions

Research Context and Group Research Priorities

The issues discussed at the scallop meeting were confined entirely to inshore Maine scallop issues and did not cover questions about the offshore Gulf of Maine or Georges Bank fishery.  Scallops have been a cyclical species in inshore Maine, occurring in patches that tend to be fished out quickly.  Research questions focus on techniques to understand the mechanisms that control abundance of scallops, thereby providing insight for actions to harvest within the constraints of the species.

Because the Maine scallop fishery has been managed largely to avoid gear conflict with the lobster fishery, rather than for biological purposes, it exists in an unusual vacuum.  On the scientific side, unlike urchins, scallops do not have a research fund and there has been little or no research done on Maine scallops in the recent past.  There is no one in DMR or the University whose primary interest is scallops, although DMR is in the process of committing staff to scallops.  Fishermen involved in spat collection for enhancement are having difficulty finding scientific advisors with capacity to help them.  On the management side, fishermen and managers have little history of interaction on resource, as opposed to gear or gear conflict, issues.  This provides an opportunity for collaboration with a relatively clean slate.

The Governor's Marine Fellowship program was suggested as one way to address the shortage of principal investigators focused on scallops.  It was suggested that fishermen be included in the mailings about the availability of fellowships, so that the fishermen, as potential one-third funders of a fellowship, could initiate ideas, seek out researchers with students, and stimulate local scientific interest in scallop questions. 

In the traditional fishery, interest in rotational management, spawning refuges, and other measures to reduce the boom and bust features of the fishery increasingly call for scientific guidance that is non-existent at this point. 


Scallop Priority 1:  Nearshore Oceanography  

As with clams and urchins, using enhancement as a lens focuses scallop research questions on understanding nearshore oceanography and scallop life history at a most basic and local level.  If spat is to be collected, the very nearshore currents need to be understood, as does the transport of spat.  The desire to collect scallop, as opposed to starfish or any other spat, focuses questions on scallop spawning behavior, triggers, and location of broodstock.  

Research priorities are:
        a)      Fine scale research and current modeling to determine scallop larval dispersement patterns. 
b)      Where is the effective broodstock for each scallop area? 
c)      What are the mechanisms that determine the relationship between adult scallop biomass and recruitment success?
     d)      Do adult scallops or scallop larvae move inshore and/or offshore? 


Scallop Priority 2:  Life History  

Life history, growth, and behavior questions also rise to the top.  What is the growth rate in scallops in different parts of Maine?  What are the significant determinants of growth?  The role of predators also emerges as important because of both the spat collection and the distribution of seed later. 

Research priorities are:
a)      What triggers scallop spawning?  Is it density dependent?
b)      Document and understand scallop growth rates in different areas.
c)      Study predation on scallops at larval and juvenile life stages. 

“First, what is the relationship between spawning stock biomass in Maine scallop beds and recruitment success in those beds?  What percentage of scallop larvae that settle in Maine scallop beds come from Maine scallops?  … Second, what is the relative value of refugia and larger ring size in terms of recruitment success in the population?”

Daniel Schick

Attachment C



Scallop Priority 3: Gear

With the national focus by environmental groups on the effects of dragging, scallopers place a high priority on credible studies of the impact of scallop gear on the bottom and its impact on the scallop resource and discard rate.  Conservation engineering on scallop gear emerged as a very high priority.

Research priorities are:
        a)      Improve the design of scallop gear to better select out juveniles, reduce discards, and reduce bottom impacts.
        b)      Develop and communicate credible methods for doing gear impact research.
        c)      Research impact of dragging on bottom and bay ecology with credible methods. 
        d)      Study cumulative effect of dragging on Cobscook Bay. 


Scallop Priority 4:  Enhancement 

Scallop enhancement activities are stimulating an unprecedented level of discussion, both about enhancement and management of the traditional fishery.  The discussion includes basic science questions, new opportunities for monitoring and assessment, and numerous policy questions.  The discussion seeks information on a very fine scale, about local phenomena rather than statewide or Gulf of Maine wide issues. 

A May, 1998 trip to Japan provided information about spat collection, bottom aquaculture and wild reseeding that supports the scallop industry in that country.  Since then, local efforts by fishermen to collect spat have started in a number of locations including Cobscook Bay, Stonington, and Saco.  The effort is in a very early stage of development.  The development of enhancement techniques provides an opportunity for collaborative work that links basic questions with specific gear and activities.  As for any reseeding or restocking effort, evaluation of its effectiveness is essential. 

Scallop enhancement is bringing to the fore policy issues about aquaculture and the wild fishery.  Enhancement is being used by some local groups to involve fishermen in stewardship of the local resource.   Enhancement techniques may prove useful to scallop aquaculturists.  There is concern about the ultimate ownership of the scallops that grow from collected spat.  A number of regulatory issues will need resolution.  

Research priorities are:
        a)      Refine scallop spat collection methodologies:  gear, oceanographic monitoring, seeding techniques and timing.
        b)      Create standard evaluation techniques for scallop spat collection, reseeding efforts.
     c)      Study the socio-economic issues of governance, community capacity, and necessary new regulatory structure for enhancement and wild scallop management. 

“Specific local areas have been important to the fishery over time.  Where does scallop seed show up over and over?  Where does scallop seed occur only sometimes, but where they grow well?”  

Richard Taylor
Attachment B



Scallop Priority 5:  Monitoring and Assessment

Maine does no assessment of scallops in the inshore area and has very little data that could be used in a formal assessment.  What emerged from the discussion was a recognition that statewide work may not be the best use of limited resources and that focus on specific areas, such as Cobscook Bay which is the center of much of the scallop fishing activity now, could provide more useful information.  Potentially enhancement could create a demand for a number of monitoring programs, including spawning, spat abundance, and currents.  Experimenting with a local, collaborative approach emerged as a good strategy.

Research priorities are:
        a)      Do a Cobscook Bay scallop assessment.
        b)      Use spat bags to develop a spawning index for scallop assessment.
        c)      Develop local scallop gonadal indices and local oceanographic monitoring.  

“No assessment of the status of the scallop stock along the Maine coast has ever been done.”

Daniel Schick
Attachment C




VII.  Scallop Observations and Questions from Discussion


Can aquaculture help the wild fishery by maintaining a large broodstock to provide eggs to it?

Are there any natural markers for scallop populations that are heritable that could provide a mechanism for tracking populations? 

Assessment and Surveys

Do scallops have natural cycles?  If so, what causes them?

Can we include younger year classes in assessments?

What is a realistic purpose for a scallop assessment?  Projection of yield from scallops that are already on the bottom?  Projection of future population levels?

Best means of getting a good scallop assessment would be to have a fishery- independent survey that samples all areas, not just the heavily fished areas.

Use spat collection as an index for assessment. 

Should inshore assessment be regional or local?

Do a Cobscook Bay assessment.

Develop an annual pre-season industry or DMR survey to determine scallop size classes on various grounds and decide whether to open based on the survey results.  This could be done statewide or in specific areas such as Cobscook.

Need a calculation of catch at age from shucked fishery.

How do you calculate fishing mortality rate in a rotational fishery?


What is the relationship between scallop spawning and starfish spawning?

What is the relationship between good scallop and starfish sets?

Do urchins and scallops compete at any life stages?

When I find a scallop bed covered with barnacles, the meats are larger.  Why?

Why is Cobscook Bay such a good place for scallops?

Compare Cobscook and Machias Bays.  Why are they so different?  Is it because of the size of the lobster fishery?


How do we repopulate areas that were once productive scallop beds?

Do an accurate assessment of what is in an area prior to enhancement.

Use a flow cam as they do in Prince Edward Island to understand the spawning dynamics and advise fishermen when the spat are in the water.

Does netron out-perform gillnet for spat collection?

What collection strategies would avoid predation?  Should we collect spat earlier? 

What are the best places to collect spat:  general characteristics and specific locations?

Mike Dadswell in Canada has found good spat collection in circular gyre over a mud hole where larvae won't settle.

What are the best places to put spat for grow out?

Should predator control be done prior to reseeding?

Develop a protocol to measure success of enhancement across the state.  Can we identify standardized measures that can be used in different places?

Need consistent protocol for collection and evaluation for enhancement statewide.

Can we identify indicators for spawning in order to establish efficient spat collection strategies?

Be careful not to spread disease through spat transfer.

Develop site specific gonadal index so that people know when to put out spat collectors.

Develop gonadal index monitoring program.

Develop a tag for the spat so we know whether enhancement is working.

Connect with Canadian 10-year spat collection time series.


Can we limit the impact of dragging on small scallops?

Are juveniles getting out of the drags?

Set up the rings so they do cull and allow fishermen to close up spaces between rings.  Hang rings staggered?

If 3 1/2" rings don't work, then research other ring sizes and configurations.  What about cookies, liners?

Solve the discard problem.  Scallops that freeze on deck are dead when they are discarded.

Can we minimize the environmental impact of dragging?

Does a rigid drag cause less damage?

When we changed drag width, we made impact worse by not addressing the weight of drags.

Collate past work on drag impacts to identify what work needs to be done.

Define better what a functional benthic (bottom) community is.  

BACI (Before, After, Control, Impact) studies assess impact by measuring change.  Look at the variability of the system in the control and test sites and then measure impact on the test site. 

Too complex to study gear impacts on the bottom given there are no untouched areas. Many variables in how dragging is done.

Need gear impact done by credible scientists.

Coordinate gear design and restrictions with what we know about the size of scallop necessary to protect as broodstock.


Examine the cumulative impacts of dragging in Cobscook Bay on the scallop population, the habitat, and the water column.  What is the impact of the sediment plumes from dragging?

Life History

Understand the role of predation through the scallop life cycle. 

Understand what triggers spawning in male and female.  What role does density of scallops play in setting off synchronous spawning?

What are the relative contributions to spawning of scallops at different sizes/ages?  Do we know what size we need to protect to preserve broodstock?

What is the relationship between parents and juveniles?  What is the source of juveniles that settle in a given location? 

Understand the factors that contribute to the very high natural mortality in scallop larvae.

Understand larval settlement coastwide. 

Canadian work on spat collection shows high levels of spat in areas they won't settle. 

Understand the variation in growth rates of larvae and adults statewide. 

Are there multiple sources of spat that supply good growth areas?

Is there any relationship between the length of the cilia and the ability to feed the way there is in urchins?

What determines color in scallops? 

Why are scallops in Calais either tiny or dead? 


How do we keep the scallop resource sustainable without privatization or ITQs?

Monitor management tools for their success:  gear restrictions, etc.

Do input controls include limits on crew size.  Those limits are significant factor. 

Are there benefits to spawning refuges or rotational management? 

To maximize egg production, should large scallops be protected the way large lobsters are?

Research regulatory options for issues such as movement of seed and protection of seeded areas.

Need to learn from other enhancement efforts worldwide:  Canada, Japan and New Zealand.

What can be learned from the Passamaquoddy Bay scallop management approach?

Migration and Behavior

Is there a relationship between foggy weather in the summer and peaks in scallop abundance historically?  If so, is it related to spawning or growth?

What are the migratory patterns of offshore scallops?  Do they move inshore?  Do they repopulate the bays? 

Is there migration of inshore scallops offshore? 

Do scallop larvae from different regions behave differently?


Understand the oceanographic characteristics that relate to scallop larval transport.

Scallop landings may be best when sea surface temperature is between 8-9° C.

Nutrient and transport questions in Cobscook Bay are important to pursuing enhancement but they need to be done at a finer scale than has been done -- ground-truthed and made real time.

Canadian circulation model uses different system for data management and may be useful in improving the resolution of the models.

Need synthesis of what is already known in layman's language for use in planning and doing collaborative scallop enhancement efforts. 

Socio-economic Issues

What are the market implications of various size restrictions such as increases in minimum size or the imposition of a large measure. 

Concern that spat collection will lead to aquaculture rather than enhancement of the traditional fishery.   

Once we develop enhancement techniques, who will own those scallops?  Will these be regional efforts?  Implications for whole fishery?

Will DMR draw the line between fishermen doing enhancement and aquaculturists doing this for personal gain?

What will the governance structure be for enhancement efforts?

Integrate the social questions from the beginning as an integral part of all the science research necessary to make enhancement work.

Don't rush to decide policy issues before we have worked out what really works and is cost effective for enhancement.

What will be the issues between scallop enhancement efforts and other fisheries?

Stock Structure

Do genetics studies to understand inshore/offshore migration and stock structure along the coast.  Are there differences between scallops?


Attachment A: 



May 16, 2000 at University of Maine at Machias 

41 Participants           

Barry Huckins                Lubec                                                                  733-2042
Jamie Huntsberger         GSH1 Sunset, 04683                                            266-2167
Rep. Martha Bagley       Machias                                                               255-6567
Sandra Wallace             Pembroke                                                            726-0651
James Wallace              Pembroke                                                            726-0651
Carlo Doria                    Portland                                                               878-2616
Anthony Doria                Lyman                                                                 499-7212
Cecil Cates                   138 Water St., Eastport 04631                               853-4423
Jesse Leach                  Rt. 15 Box 1220, Penobscot 04476                        326-4719
Ralph DeWitt                 9 High St., Eastport 04631                                    853-0662
Hank Stence                  Lubec                                                                 733-4489
Lanny Wood                  HCR 70, Box 36, Machiasport                               255-8854
Bruce McInnis                1 High St., Eastport 04631                                   853-4328
Austin Humphrey            P.O. Box 94, Perry 04667                                    853-6694
Marsden Brewer             RFD Box 1455, Stonington 04681                         367-5100
Donna Brewer                 RFD Box 1455, Stonington 04681                         367-5100
Brian Beal                      University of Maine, Machias                                255-1314
Jane Harrison                 HC 70 Box 28, Machias 04654                             255-3841
Dan Placzek                   37 Hillside Rd, Orono 04473                                866-3700
David Cox                       Box 153, Searsmont 04973
Harry Shain                     P.O. Box 27, Perry 04667                                   853-2518
John Higgins                   UM Darling Marine Center, Walpole 04573            563-3146
Dennis Fraughton            2161 Friendship Rd, Waldoboro 04572                  832-4389
Richard Taylor                 Box 7002, Gloucester, MA                                  978-281-2718
Kenny Daye                    27 School St, Lubec 04652                                 733-0908
Bill Daye                         27 School St. Lubec 04652                                 733-0908
Sean Daye                      27 School St. Lubec 04652                                 733-0908
Kristan Porter                                                                                          259-3306
Will Hopkins                    4 Favor St., Eastport 04631                                853-4560
Anne Hayden                   6 Bowler St., Brunswick 04011                           725-9743
Jim Dow                          P.O. 974, Blue Hill 04614                                   374-2998
Dana Morse                     Sea Grant / UM Cooperative Extension               563-3146 x205
Linda Mercer                    DMR, Boothbay Harbor                                     633-9525
Laura Taylor                     DMR, Augusta                                                 624-6576
Penn Estabrook                DMR. Augusta                                                 324-6553
Sue Inches                       DMR. Augusta                                                 642-6558
Dan Schick                      DMR, Boothbay Harbor                                     633-6528
Paul Anderson                  Sea Grant / UM Cooperative Extension              581-1422
Chris Bartlett                    Sea Grant /UM Cooperative Extension               853-2518
Don Perkins   Gulf of Maine Aquarium
  PO Box 7549, Portland  04112        871-7804
Robin Alden                     PO Box 274, Stonington 04681                         367-2473



Attachment B: 

Very Brief History of Scallop Seeding 
Richard Taylor, Scalloper, Gloucester, MA 

Maine DMR Coastal Fishery Research Priority Meetings 

May 16, 2000 

I.    Spat collection from the wild and reseeding:  Japan, New Zealand, Magdalen Islands, Canada 

II.  Hatchery based seed production for contained culture:  China, Chile, France 

III.   Choices:  What do you want the scallop fishery of the future to look like? 

1.      Status quo - meaning continue the way the fishery is now:  "findem, catchem." 

2.             Develop area management, where scallops are allowed to grow to a large size to increase the value of each scallop.  With the success of the 1999 Maine inshore spat collection, you can see the size of these animals at the end of the year, about the time the scallop season starts. 

3.   Begin small scale spat collection to start getting a better sense of the potential of reseeding small scallops.  The initial effort last fall was quite productive.  One advantage of the spat collection/reseeding method is that scallop can be put out in areas where they don't show up very often but where we know from occasional sets in the past that they will thrive.  Reseeding a single year class allows letting scallops grow before going through them with the gear. 

4.             Develop intermediate culture areas where scallops within spat collectors can be left to grow to a size suitable for reseeding. 

5.             Develop contained scallop culture (cages, lantern or pocket nets).  This option offers the benefit of maintaining a larger spawning biomass to increase larval supply to the fishery and for spat collection. 

6.   A combination of most or all of the above. 

IV. Yield or landings as a function of the number of participants: 

An increase in the scallop population will result in increased landings and increased total earnings, however as long as the numbers of boats are allowed to increase unchecked earnings for each boat will stay about the same.  There are at least two approaches to this situation. 

One method is to limit the number of licenses, that is, limit the number of slices of the pie, and with this comes a particular set of other problems involving who gets to participate. 

Another solution is to greatly increase the number of scallops by using methods that increase the survival of scallops during the first year, or 'grow the pie bigger'.  The Japanese system had a stated objective in 1970 of increasing economic development in fishing communities.  Their methods have allowed increased participation by a larger number of fishermen and increased employment in the processing sector.   

V.     Topics for further research and consideration: 

  1. The fishing grounds: 

Specific local areas have been important to the fishery over time.  Where does scallop seed show up over and over?  Where does scallop seed occur only sometimes, but where they grow well?  We know that scallop larvae are carried by the currents for about 40 days and we can see that certain areas seem to retain the larvae repeatedly.  The role of bottom type or substrate is a key factor here:  generally we know that gravelly areas seem to have a lot of scallops.  We know that the role of predators such as starfish and crabs is important as well. 

      Although it would be great to get the best scientific level information about these areas, we don't have to completely understand and document the 'why' of it to treat these areas as special.  Every fisherman who has been a part of the industry knows pretty much where they are.  The harder question is how these areas should be managed to maximize what they already provide.  The success of the area closures on Georges is one way to go, but is much easier to enforce when the areas are a hundred miles offshore and each scallop vessel has a satellite-tracking device.  It's a harder problem to solve inshore and really goes to the issue of how we think about what we are doing. An old skipper of mine said way back,  'Do you think human nature is going to change?'  Probably not, but if you see there is more product and more money to be made by doing something a little different, that change will come. 

  1. Basic scallop biology: 

Some basic information will help us to make better choices looking ahead.  Perhaps the most important is figuring out when and where spawning occurs.  Generally we figure it is in the fall but this is one aspect that needs to be documented if spat collection is to be reliably integrated into any future plan.

 VI.      Bibliography: 

These papers have provided insight into the many parts of the solution: 

Bull, M.F. (1994) Enhancement and Management of New Zealand’s 'Southern Scallop' Fishery, In Proceedings of the 9th International Pectinid Workshop, Nanaimmo, BC, Canada, April 22-27, 1993, Bourne, N.F., B.L. Bunting, and L.D.Townsend (eds), Vol. 2, pp131-136. 

Cliché, G. and M. Giguere (1998) Final report of the research program on scallop culture and restocking (REPERE), 1990-1997, Canadian Industry Report of Fisheries and Aquatic Sciences 247, 74 p. 

Dow, R.L. (1971) Periodicity of sea scallops abundance fluctuations in the Northern Gulf of Maine, Maine Dept. Sea and Shore Fish. Res. Bull. 31. 

Gallager, S.M., J.L. Manuel, D.A. Manning, R. O'Dor (1996) Ontogenetic changes in the vertical distribution of giant scallop larvae, Placopecten magellanicus, in 9-m deep mesocosms as a function of light, food, and temperature stratification, Marine Biology 124:679-692. 

Hatcher, B.G., R.E. Scheibling, M.A. Barbeau, A.W. Hennigar, L.W. Taylor, A.J. Windust (1996) Dispersion and mortality of a population of sea scallop (Placopecten magellanicus) seeded in a tidal channel, Canadian. Journal of Fisheries and Aquatic Sciences, 53:38-54.  

Ito, H. (1990) Some aspects of offshore spat collection of Japanese scallop, in Marine Farming and Enhancement, Proceedings of the 15th US-Japan Meeting on Aquaculture, A.K.Sparks (ed), NOAA Tech. Report NMFS 85, 85:35-48.  

Ito, H. (1991) Successful HOTAC methods for developing scallop sowing culture in the Nemuro District of East Hokkaido, Northern Japan, in Marine Ranching, Proceedings of the 17th US-Japan Conference on Aquaculture, R.S. Svrjcek (ed.), NOAA Tech. Report NMFS 102, 102:107-116. 

Ito, H. (1992) Breeding season of Japanese scallop off the eastern coast of Hokkaido, Marine Ranching, in Proceedings of the 18th US-Japan Conference on Aquaculture, R.S. Svrjcek (ed), NOAA Tech. Report NMFS 106, 106:77-83. 

Ito, S. and A. Bykuno (1990) A history of scallop culture in Japan, in Proceedings of the Australasian Scallop Workshop 1988, M.C.L. Dredge, W.F. Zacharin, and L.M. Joll (eds.), Tasmanian Government Printer, Hobart, Australia, pp. 166-181. 

Levitan, D.R. and M.A. Sewell (1998) Fertilization success in free-spawning marine invertebrates: review of the evidence and fisheries implications, in Proceedings of the North Pacific Symposium Invertebrate Stock Assessment and Management, G.S. Jamieson and A. Campbell (Des), Canadian Special Publication of Fisheries and Aquatic Science 125, pp.159-164. 

Tegner, M. J. (1989) The feasibility of enhancing red sea urchin, Strongylocentrotus franciscanus, stocks in California, Marine Fisheries Review, Scientific Publ. Office NMFS, Seattle, Wash., 51(2): 1-22. 

Thompson, J. (1990) Administrative, legal and sociological difficulties of scallop culture enhancement. Proceedings Australasian Scallop Workshop, M.C.L. Dredge, W.F. Zaccharin, and L.M. Joll, (eds.), Tasmanian Government Printer, Hobart, Australia, pp. 264 -271. 

Wing, S.R., L.W. Botsford, J.F. Quinn (1998) The impact of coastal circulation on the spatial distribution of invertebrate recruitment, with implications for management, in Proceedings of the North Pacific Symposium Invertebrate Stock Assessment and Management, G.S. Jamieson and A. Campbell (Des), Canadian Special Publication of Fisheries and Aquatic Science 125, pp. 285-294.


Attachment C: 

Scallop Assessment and Management 
Daniel Schick, Maine Department of Marine Resources 
Maine DMR Coastal Fishery Research Priority Meetings 

May 16, 2000

The population biology of a stock can be described in a few simple terms.  First, there are three factors that can make the population grow, or make the biomass larger.  The first is recruitment:  the addition of animals to the stock through reproduction.  The second is growth of individuals.  The third is immigration of animals into the area defined as being the location of the stock.  There are three factors that can make the population decrease, or make the biomass smaller.  The first is natural mortality, which includes death due to old age, disease, or predation.  The second is emigration:  the moving of animals out of the area defined as being the location of the stock.  The third is fishing mortality, or death caused by fishing activity of man.   This can be divided into individuals caught and kept, caught and discarded but died anyway, and individuals killed by the fishing activity but not caught. 

In managing a stock, there is usually only one of the above factors that can be manipulated to influence the size of the biomass of the stock and that is fishing mortality.  In the case of the sea scallop, it may be possible to manipulate the recruitment of individuals into the stock as well as fishing mortality. 

Assessment of the status of a stock can be done by several methods.  The method used depends on the data available and the length of time that data has been gathered.  Some indices of abundance can be obtained from the landings record, especially if the landings can be broken down by area fished.  If there is any effort information collected in the fishery, i.e. number of hours fishing, the catch per unit of effort can provide another index of abundance.  If there is any biological data collected from the fishery, i.e. size frequency of scallops caught, then a catch at age matrix can be developed and more sophisticated population models can be used.  Finally, if there is a fishery independent survey of the population from which a separate catch per unit effort (CPUE) index and catch at age matrix can be produced each year, then the data lends itself to the best modeling possible.   

Most of these data elements are available for the offshore scallop population and that population has been modeled using the Collie-Sissenwine modification of the DeLury model for USA stocks.  This model estimates biomass and total mortality and is based on survey indices of abundance and fishery removals at size, or assumed age.  The catch at size is not always well represented, which increases the error in the model results.  Canadian assessments give indices of abundance on the basis of survey data, logbooks and port sampling data and in periodic assessments they use cohort analysis, or separable virtual population analysis to generate estimated numbers at age, biomass at age and fishing mortality (F) at age.  From this data they use a yield per recruit analysis to develop Fmax (fishing mortality rate that will give maximum yield/recruit) and F0.1 (fishing mortality rate where the slope of increasing yield with increasing F is a tenth of the initial slope) and then develop catch projections using these F’s, other selected F values and assumed average recruitment to predict biomass over the next year and therefore what the TAC should be under various fishing scenarios.  In some assessments, the Canadians use a Leslie depletion estimator to generate an exploitation rate from catch, effort and survey data.  The F from the exploitation rate is compared to Fmax and F0.1 values to assess whether the fishery is taking too much. 

The State of Maine collects scallop landings information, but collects no effort data, nor does it do any fisheries independent survey work.  Thus the State has little information with which to determine the status of the stock of scallops along the coast.  The National Marine Fisheries Service does not do a scallop survey in the Gulf of Maine.  As a result, almost nothing is known about the stock.  No assessment of the status of the scallop stock along the Maine coast has ever been done. 

There are two general types of controls imposed on fisheries to limit fishing mortality.  They are input controls, related to limiting effort, and output controls, related to limiting catch directly through some form of quota.  Input controls can be limits on season length, days at sea, boat size, numbers of vessels, gear restrictions, etc.  Output controls can be limits on catch per trip, individual quotas, or overall annual or seasonal quota. 

In the current Maine scallop fishery, management is based on input controls, i.e., season length and gear size (dredge width) restrictions.  Traditionally there has been a 3" shell height minimum and more recently a graduated 3" to 3-1/4" to 3-1/2" ring size increase.  The ring size limits are the first regulations that deal with the biology of the scallop.  The season timing and duration is simply a measure for reducing gear conflict with fixed gear fisheries, rather than anything to do with the capacity of the scallop population to support the fishery.  The drag width limits have more to do with competition between different vessel size classes and their associated socio-economic differences than condition of the stock.  The minimum shell size was purportedly directed at the minimum spawning size of the scallop, but was unenforceable, as the unshucked scallops were a mix of the legal and too small scallops on the sorting table and the relationship between shucked meat size and shell size was not a good one.  

The ring size minimum of 3-1/2" starts to address the need for considering the rapid growth rate and rapid increase in meat yield as scallops increase in size.  Once a scallop reaches 3", its meat yield will almost double each year it is allowed to grow for at least the next three years.  Allowing scallops to increase their meat yield prior to capture increases their yield per recruit.  It may well be that the best yield per recruit, and therefore the best yield from the resource can be gained by using 4", or perhaps larger rings. 

In order to build a management plan for scallops in coastal Maine, we need to establish some goals in terms of what we want from this fishery.  Do we want greater yield per recruit?  Do larger meats command a better price in the market?  Do we want a consistent annual harvest rather than the boom and bust fishery evident from the landings record?  Will protecting a portion of the spawning stock biomass provide us with a constant supply of recruits?  

We might gain some insight by looking at the offshore scallop fishery along the East Coast.  For years the fishery was severely overcapitalized with too many large vessels that had a combined capacity easily capable of fishing down each successful year class very quickly.  This created a fishing mortality rate that was much too high and the boom or bust landings typical for that scenario.  A few years ago, large areas of Georges Bank scallop grounds were closed to scalloping due to depletion of the groundfish resources there.  The scallops in these areas increased in size each year and new recruits settled into these areas and grew in good concentration.  After three years, there was a huge biomass of scallops there.  Some of these areas have been opened to scalloping on a limited basis and two areas off the mid-Atlantic were closed due to the heavy concentration of small scallops there.  

A system is evolving in the offshore fishery that is based on rotating open and closed areas to maximize yield per recruit by protecting juvenile scallops until they reach optimal market size.  A system such as this might work very well along the Maine coast, especially if the recruitment to the resource is enhanced by the capture and growout of scallop spat for release at a size that is beyond the high natural mortality size range.   If the scallop population biomass grows, especially at the hands of fishers engaged in enhancement of the stock, the issue of how many more fishers to let in to the fishery will have to be addressed. 

In order to choose what form of management is appropriate for Maine scallops, there are two huge questions to be answered.  First, what is the relationship between spawning stock biomass in Maine scallop beds and recruitment success in those beds?  What percentage of scallop larvae that settle in Maine scallop beds come from Maine scallops?  If a reasonable percentage of Maine scallops are a product of Maine scallop spawning, then there is a good reason to manage the scallop stock to protect the spawning stock at some appropriate level.  If there is no parent progeny relationship, then there is no need to maintain a spawning stock biomass and the best management would be to maximize yield per recruit.  

The second question is what is the relative value of refugia and larger ring size in terms of recruitment success in the population?  In a refuge, all scallops are protected and with a large ring size, scallops are allowed to spawn before recruiting to the fishing gear.  In a refuge, large scallops would exist in close proximity presumably to maximize their spawning synchrony and therefore spawning success.  With large ring size, all scallops would spawn before being caught, providing a much wider distribution of scallop spawning.



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