Pilot aquaculture production of sea scallops (Placopecten magellanicus) in Maine, Japanese technique

Project Overview

Project Type: Partnership
Funds awarded in 2016: $14,665.00
Projected End Date: 04/15/2019
Grant Recipient: University of Maine
Region: Northeast
State: Maine
Project Leader:
Dana Morse
Maine Sea Grant and University of Maine Cooperative Extension

Annual Reports

Information Products


  • Animals: shellfish


  • Animal Production: aquaculture
  • Education and Training: on-farm/ranch research
  • Farm Business Management: agricultural finance, feasibility study, labor/employment, new enterprise development
  • Production Systems: aquaculture, shellfish production

    Proposal abstract:

    The Issue: Aquaculture for sea scallops (Placopecten magellanicus) is recognized as an alluring opportunity for Maine producers (Anonymous, 2001), though a challenging one. Scallops are a high-value crop, they grow well in Maine’s coastal waters, and a growing market exists for the already half-billion dollars’ worth of scallops harvested from the wild fishery. Maine scallops command a premium, with ex-vessel prices exceeding $12.70/lb (Anonymous, 2014); and an aquaculture crop has the additional advantage of year-round supply, compared to the seasonal fishery. Cage culture is expensive because scallops require space to grow well, and cannot be grown in high densities, as oysters can, but the technique known as ‘ear-hanging’ presents unique opportunities for scallop culture in Maine. Our Objective: Building on existing, leading work by Maine growers in scallop aquaculture, we will evaluate the established Japanese technique of ear hanging as a cost-effective culture method. Key Components: Over the course of 18 months, five Maine aquaculture farms and one experimental/demonstration station will grow pilot-scale numbers of ear-hung scallops, to evaluate parameters such as growth rate, mortality, adductor muscle (meat) weight, fouling, best husbandry practices, and cost inputs for labor and equipment. Resulting data will form the basis by which growers make decisions about investing in the necessary equipment for larger-scale production. Results will be made publicly available, and will be transmitted to other producers, regulatory agencies, buyers and scientists. If successful, strong groundwork will have been laid for a new, highly productive and valuable aquaculture sector.

    Project objectives from proposal:

    Our work addresses the central question:
    Is ear-hanging a profitable aquaculture production method for sea scallops in Maine?

    Our goal is to create a new aquaculture sector in Maine.
    To that end, this project addresses the following objectives:
        1. Document growth rates of scallops grown via ear hanging
        2. Understand the yield/value of ear-hung scallop meats
        3. Begin to estimate the costs for growing ear-hung scallops

    Although the Partnership Grant is limited in scope, this project could easily have an inordinate impact. Interestexists to develop ear hanging through investment in farming infrastructure, provided that the biological parameters and husbandry methods are conducive to such investment. In short: if we can provide data that indicates a >positive outlook, new investments are likely to follow, with concurrent impacts on landings, value and waterfront jobs.

    Past work
    This project builds on over a decade of experimentation in seed collection, stock enhancement and cage culture production in Maine. We can procure a steady supply of scallop seed, and can grow a high quality product in a rapid time frame (http://www.seagrant.umaine.edu/research/projects/dv/scallop-trials). We know that growth rates compare quite favorably with other work done in the state, and to growth rates published elsewhere (Pottle and Hastings, 2001; Kuenstner 1996; Smolowitz, 1999). Product sold into the live market in recent years has captured excellent value; $1-3 per piece (Morse, unpublished). The principal problems with cage-cultured, live-market production are twofold: live sales require a prohibitively expensive level of product testing to document safe levels of phycotoxins (those that cause so-called red tide poisoning); and secondly, that cage-grown scallops do not perform well at high stocking densities, meaning high capital costs for equipment. We propose to use the ear-hanging method, whereby scallop shells are drilled through one shell near the hinge, and attached to a specialized plastic pin (‘age-pin’ - pronounced ‘Ah-gay’) that has been inserted into a growout line. Lines are hung vertically in the water column, and allowed to grow from one to three years. Scallops must be cleaned periodically, but work by Grant et. al. (2003) indicated that the adductor muscle - the most marketable part of the scallop - grew significantly faster using ear hanging, than through cage culture. Small trials with earhung scallops in Maine recorded growth rates at 0.09mm/day during winter months (Morse, unpublished), an encouraging rate which bodes well for year-round production.

    This project differs from our earlier work, which has focused on the live market. Our understanding of the earhanging method has emerged through the sister-state relationship between Maine and Aomori Prefecture, Japan, and through this relationship a major manufacturer of ear-hanging equipment (Mutsu-Kaden Tokki Co., LTD) has assisted with donated ear-hanging lines and advice, so that we can evaluate the method here in Maine. This access to expertise and equipment is a major benefit to the development of this new farming technique. Specifically, a Maine delegation visited Aomori in 2010 - including project partners Davis and Cowperthwaite - and met with Mr. Hiroaki Sugiyama, owner of Mutsu-Kaden, and were given a tour of his plant and the production methods (https://www.youtube.com/watch?v=B3OW3RrTo3E). Mr. Sugiyama’s most recent visit to Maine was through the auspices of Coastal Enterprises Inc in 2014; he presented his equipment and ear-hanging methods (posted at: http://www.seagrant.umaine.edu/resources-for-shellfish-growers/species/scallop) to several shellfish. Mr. Sugiyama obviously sees a business opportunity for his company here in Maine, because the fundamentals of Maine scallop production appear soli


    Production Trial
    Five shellfish farms and one research/demonstration farm will be outfitted with ear hanging lines sufficient to grow
    at least 1000 scallops. NOTE: 200 scallop lines are being donated by Mutsu-Kaden Tokki Co in support of this project, and the Maine Aquaculture Innovation Center has purchased a high-speed drill for use in the project specifically. Scallops (provided by the producers) will be drilled in the upper hinge only, in the byssal groove of the lower valve, with a 1.5mm diamond-tipped drill. Per earlier observations and recommendations from Japan, minimum scallop size at drilling will be 45mm. Scallops will then be attached manually to each pin, such that the barb of the pin comes through the upper valve - this positioning prevents the barb from coming in contact with soft tissues, which could cause damage. Initial measurements will be taken on shell height/length/width and live weight: 50 individuals as a representative sample for the initial size. These individuals will form one line, and will also be tagged individually, by attaching a Tyvek tag to the barb of each pin, marked with permanent marker. In this way, both group growth and individual growth can be tracked. A data-logging temperature sensor (Onset Instruments TidBit) will accompany each line of tagged scallops, so that we can develop observations about the important relationship between temperature and growth.

    Quarterly, each farm will be visited by Sea Grant and/or MAIC staff to assess growth, mortality, general condition and to document husbandry considerations and suggestions as given by each farmer, for later distribution to interested individuals. One line will be chosen at random by the producer, and all scallops (50) will be measured for length/weight/height/mortality. We will avoid measuring the same line for each visit, to avoid accumulated effects from sampling stress. At the end of the project - November, 2017 - a final sampling will include one line chosen at random and the individually-tagged line. These will be evaluated for all prior parameters plus weights for adductor muscles (meats), roe and viscera. Sampling will produce information on the effects of depth, and an estimate on the yield of the harvest, which will be compared to historical values for dayboat scallops, to arrive at a value of the crop; we will also request that producers report on the prices received for any sales from this crop.

    The project will begin in April of 2016.

    Track labor and capital inputs
    We will track input costs such as equipment (ear-hanging lines, other ropes, buoys, anchors, etc) and labor (such as for drilling, maintenance, harvesting), to begin to estimate the costs for ear-hanging production. The scope of the available funding does not permit a thorough production model, but we can begin to understand the major
    inputs in an organized fashion.

    Document husbandry considerations
    Husbandry techniques, observations, operational details and all results will be captured in photos and videos, so that others can learn about our work. All materials will be posted to the Maine Sea Grant web site; references earlier in this proposal give examples of the intention and ability for project partners to make information readily available to any interested individuals.

    Evaluate low-cost seed production
    The equipment to procure seed stock is simple and effective, having been adapted from proven Japanese technology. The central equipment is a ‘spat bag’ consisting of a polyethylene mesh (1.5mm mesh opening) bag the size of a bed pillow, and a larger-sized polyethylene mesh ‘stuffing’ which provides good substrate for scallop larvae to colonize. A video of the process exists: https://www.youtube.com/watch?v=NZBI9hN2e9Y. The stuffing material most commonly used is called “Netron” and is very expensive - roughly $300 for 300 linear feet. We will examine commonly-available agricultural nettings, to see if collection performance compares to Netron. Specifically, we will evaluate three commonly-used polyethylene netting products from International Netting Inc: OV-7100 (1/6” mesh), OV-7822 (1/4”) and OV-1581 (1/2”); these are all less than one-third the cost of Netron. We will deploy four spat collection lines, which hang vertically in the water. Each line will have four spat bags at a given depth stratum; one bag of each mesh type, and each line will be divided into three depth strata (surface, middle, bottom), for a total of 12 spat collectors per line, and 48 spat collectors overall. Spat lines will be set in September of 2016, and retrieved in the spring of 2017, per customary procedure. For each bag, we will:- measure dry-pack volume (ml) of all bivalves - retain three 10ml dry-pack samples per spat bag - evaluate each sample for number bivalves, by species - measure 30 scallops chosen at random, for size frequency - extrapolate numbers/volume from our samples to the entire bag volume, to arrive at an estimate for total number of scallops caught by each collector. By calculating simple means and standard error for our catches, we will determine if catches are different between mesh types, per depth stratum.

    Production Trial
    Who: Morse will coordinate, with all collaborating farmers, student help (to be hired), Davis and Cowperthwaite. When: Begin seeding in April of 2016, project to terminate November 2017 (20 months). This aspect of the project is a 12-months-a-year activity, with sampling possible at any month, provided that weather is acceptable. Producers will supply their own scallop seed of an appropriate size for ear-hanging, above 45/50mm. Labor/Capital Inputs
    Who: Cowperthwaite will lead, with all producers. Commence at project initiation (April, 2016), complete in 20 months (November, 2017). Cowperthwaite will communicate with producers throughout the project, to gather information as the producers acquire experience.
    Husbandry Documentation
    Who: All producers, Morse and Davis will compile and organize observations
    When: Throughout entire project; updates given quarterly to project web page, and summarized at end of project
    (Nov 2017)
    Seed Production Trial
    Who: Cowperthwaite coordinate, Morse and Davis assist, Nate Perry is the collection expert.
    When: Commence September 2016, June 2017. Spat collectors are commonly deployed at the end of September, and retrieved between May and July of the following year, when the spat have grown to a size that can be transferred to nursery or growout gear.

    Outreach plans

    Who: Morse, Davis and Cowperthwaite coordinate.
    When: Updates will be posted to project web page quarterly at minimum, an initial article to be submitted to an appropriate outlet at commencement of the project, and again a year later (April-June 2017). A presentation will be requested for the 2017 Maine Fishermen’s Forum, normally held in March. We will design and implement a workshop for growers and others to take place October of 2017, near the end of the project. We will have collected sufficient experience and data at that point to be of value to prospective growers, regulators and others.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.