Principal targets in this period were to:
- Seed 5 shellfish farms and one research farm with ear-hung scallops
- Visit deployment sites to make observations on growth rate, mortality, water temperature, fouling and other operational considerations.
- Deploy alternative spat collection materials, to evaluate effectiveness and profitability
- Begin to track labor and equipment costs
- Create a project web page for hosting details on the effort
Diversification is the biggest need for Maine’s seafood harvesting industry, and the communities that the industry supports. Roughly half of the state’s 9000+ fishermen are lobstermen, the value of the lobster catch accounts for nearly 80% of the statewide landings value – and in the eastern portion of the state, the reliance on lobster is closer to 90% (ME DMR data, 2014). This reliance is inherently precarious – but options to make money working on the water are highly constrained by low stock levels and/or highly limited availability of permits and licenses to diversify into other fisheries. Aquaculture is presently the most promising avenue for diversification, for seafood harvesters. Marine aquaculture in Maine is dominated by the salmon industry, which is typified by high capital investment, and multinational competition – inaccessible to individual fishermen. There is a much smaller shellfish sector, and this sector is growing most rapidly in terms of new businesses being formed. Shellfish is dominated by production of eastern oyster (Crassostrea virginica) and blue mussel (Mytilus edulis). Yet, several studies have indicated that the sea scallop grows well in culture in the state’s waters (Pottle and Hastings 2001, Kuenstner 1996, Morse unpublished data), and the Maine scallop commands top dollar in the marketplace, when compared to trip-fished scallops or imported product. Promisingly, the market for sea scallop meats is large, and increasing.
The US sea scallop fishery is the largest in the world at over $500 million ex-vessel value, and yet ex-vessel prices have continued to increase over time, as supplies of scallops from other parts of the world have experienced setbacks. (http://www.undercurrentnews.com/2015/06/23/us-scallop-prices-to-increase-through-season-on-short-imports/).
Taken together – a working-waterfront need for diversification, strong indications of good growth of scallops in culture, and an improving market – and the opportunity for scallop aquaculture in Maine is clear.
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.
This annual report covers the performance of the current project through the end of 2016. To date, the project has met several of its technical performance actions and measure, has fallen short on some, and has exceeded others. Overall, the actions undertaken in 2016 have advanced our knowledge significantly on the capacity of the ear-hanging system to produce a quality aquaculture product, and it has contributed strongly to the overall understanding of the method well beyond simply the project team. P. magellanicus appears well-suited to this technique in terms of encouraging growth rates and low mortalities, but it is evident that site selection will play a central role in influencing the amount of biofouling control needed, and ultimately, profitability.
1. Three shellfish farms (Atwood, Fischer, Moretti) and one research farm (Darling Marine Center) have been stocked with ear-hung scallops: Atwood approx 600 individuals, Fisher approximately 550 individuals, Moretti approximately 600 individuals, Darling Center approximately 300 individuals) . Note that the N. Perry site was removed from the project at Mr. Perry’s request, because permitting was not forthcoming from the state regulatory agency, that would allowed the site he had in mind to be created. The Fischer and DMC sites have been limited by availability of suitable size scallop seed, but more than enough have been deployed to support an organized data collection and observation effort.
2. At the DMC, Atwood and Fischer sites, scallops have been drilled at different positions on the ear, to mimic research by Hamada et. al. (2001). Details on this are below. Repeated visits have been made to the Atwood, Fischer and DMC sites for collection of growth and mortality data. Data have also been collected on water temperature, together with observations on fouling, handling and other operational considerations.
3. To date, only a modest effort has been made to reconnect with producers to track time and effort, but this item will be summarized principally in 2017.
Observing Growth and Survival on Ear-Hanging Lines, and Effects of Drill Position on Growth, Survival and Yield of Ear-Hung Scallops
In 2017, scallops hung previously at the Atwood site were found to have been lost over winter; all equipment was gone. Several lines of scallops were measured, tagged, drilled and deployed for the Moretti farm in Casco Bay, but these lines were damaged in the transportation between the drilling location and the farm site. No data were recovered from this January cohort. However, a second cohort was measured and deployed August 3 2017, and successfully made the transition to the farm site. On June 22, two lines of 70 scallops each were measured, tagged, and deployed to the farm site of the Maine Scallop Company in Casco Bay. These were evaluated and cleaned on 31 August 2017, and were found to be in good condition. Growth and survival intervals were recorded. Two different cohorts callops deployed to the site of the Pemaquid Mussel Farms (PMF) on the Damariscotta River were evaluated during 2017; a set of four lines that were drilled in different positions, and a set of lines that had been deployed for over a year. Final analyses of those growth, survival and yield parameters have not yet been summarized. A set of scallops that had been grown in different nursery densities (30% and 60% bottom coverage) at the Darling Marine Center were prepared and deployed to the PMF on November 15, 2017, as an additional element to this project.
Spat Collection Using Alternative Substrates for Settlement
The spat collectors deployed under this project in fall of 2016 were retrieved in summer of 2017, and evaluated for the effects of depth and settlement substrate material on numbers and sizes of scallops and other bivalves that settled in the collectors. An intern (Melissa Britsch) was hired for the project and mentored by D. Morse and Dr. Heather Leslie, Director of the Darling Marine Center. Ms. Britsch performed analyses of the scallops retained in the collectors and summarized the outputs in spreadsheet form. Subsequent to the successful 2016/2017 deployment, and encouraged by the results seen in that experiment, a second deployment was added to the experiments covered by this project. An additional suite of spat collectors was deployed by N. Perry, D. Morse, M. Britsch in the fall of 2017, and will be retrieved in spring/early summer of 2018. This experiment uses four substrate materials: Netron (standard), 1/4″ polyethylene (inexpensive and equally-productive substitute for Netron) and two other common agricultural nettings: Plurima and R9.
In the spat collection season of 2017-2018, we repeated our spat collector experiment with Nate Perry, and modified it to expand upon what we learned in the prior season. Four lines of experimental collectors were deployed, each with three sets of four collectors, with one set of collectors in the upper water column, one in the middle of the water column and one set of collectors in the lower third. Each replicate set contained the standard material (Netron) and the OV7822 material that was so successful in the prior season. We also tested two other materials, both from the Tenax Corporation: Plurima and R9. Collectors were retrieved in the spring of 2018 and evaluated for numbers of spat, size distribution of spat collected, and with notes made on other species retained incidentally in the catch. Early indications are that the Netron and the OV7822 performed comparably, and that the other materials performed less well. Overall, spat collections were much reduced from the 2016-2017 season.
During the 2018 project year, all ear-hung scallops were sampled for a final time, at the sites for Pemaquid Mussel Company (Damariscotta River), Bangs Island Mussels (Casco Bay) and the Maine Scallop Company (Casco Bay). Measurements were made on shell dimensions, shell weight, and weights for the adductor muscle, gonad (if present) and the remaining viscera. Data will be summarized to give means for each site and to calculate growth rates (given in mm/day for shell height). Limited temperature data are available as well to help describe each site.
A presentation about the project was made to fishermen, shellfish growers and others at the 2017 Maine Fishermen’s Forum. Ms. Britsch prepared a document for distribution to participating shellfish farmers and others to describe the methods and outcomes of spat collection experiment of 2016/2017. Plans are underway to report the outcomes of the project to date, at the 2018 National Shellfisheries Association annual meeting, in Seattle, WA – March of 2018. A number of emails and conversations have continued through 2017 to existing and prospective shellfish producers, and information about the project (including early results) have been incorporated into the curriculum for Aquaculture in Shared Waters, an aquaculture training program developed and implemented by Maine Sea Grant, University of Maine Cooperative Extension, Maine Aquaculture Association, Maine Aquaculture Innovation Center and Coastal Enterprises Inc. NOTE: the scallops that were hung at the PMF, Moretti and Maine Scallop Company sites have all been quite useful as demonstration material for other producers and for Japanese experts. Mutsu Kaden Tokki Co staff were in Maine twice in 2017 and both times encountered the scallops used in this study.
There have been a variety of impacts, outcomes and contributions from this fieldwork already; some anticipated and some not. A summary is as follows:
– Data on growth has proceeded apace, particularly well at two sites and to a smaller degree at two others. Growth rates appear to be consistent with other observations of scallops culture in Maine (Morse, unpublished; Kuenstner 1996, Kuenstner 1998, Pottle et al, 2000), and better than several such estimates. Such data is of interest to the several new producers of scallops in the state, who are considering ear-hanging as a potential technique.
– We were able to make use of the lines donated by Mutsu Kaden, to examine the question of what is the best position on the scallop shell, in which to create the ear-hanging hole. Work by Hamada et al indicated that a single drill hole through the upper shell (Itimae-ake in Japanese) is preferable to drilling through both shells (Nimai-ake), because the single-shell approach limits damage to soft tissues. We have created smaller reproductions of this research at the Atwood, Fischer and DMC sites, and early returns are consistent with Hamada’s observations. For example, at a recent visit to the Atwood site, the Itimae-ake scallops were growing at a rate of just over 0.1mm/day, whereas the Nimai-ake scallops were growing at just over 0.06mm/day, even though the two sets of scallops were growing immediately next to one another. This reinforces the approach set forth by Hamada and reinforced by Mr. Sugiyama (personal communication), and will be a useful consideration for producers. Similarly, we have been able to recover dataloggers from the Fischer and Atwood sites, and have downloaded the temperature data for both sites.
– We have been able to observe very different fouling communities for all sites investigated. For example, the Fischer site is typified by solitary and colonial ascidians such as Botryllus schlosseri (golden star tunicate), Botrylloides violaceus (orange sheath tunicate), Ciona intestinalis (sea vase) and Ascidiella aspersa (European sea squirt). Just upriver from the Fischer site is the DMC site, and fouling there appears to be filamentous green and brown macroalgae (unidentified). Tubularia is common at both sites and the Fischer site interestingly had a set of Palmaria palmata (Dulse) very near the surface. The Atwood site is typified by harder fouling organisms such as the common barnacle (Balanus sp) and blue mussel (Mytilus edulis), as well as colonial tunicates B. schlosseri and Didemnum vexillum. It is clear that cleaning of lines at all locations observed will be necessary at several times per year. This is in contrast with advice from Mutsu Bay producers who observe that once or perhaps twice per year is necessary for cleaning. We regard this as effect of depth; the scallops in the current study are hung very near the surface, whereas the Japanese producers employ ear-hanging lines beginning at 15’ or so from the surface; this specifically to limit biofouling and the adverse effects of too much turbulence at the surface.
Education & Outreach Activities and Participation Summary
A project web page has been created for this project, at http://www.seagrant.umaine.edu/aquaculture/resources-for-shellfish-growers/species/scallop/ear-hanging
A presentation on the project was made at the Northeast Aquaculture Conference and Expo (NACE), in January of 2017; NACE was attended by approximately 500 people over the two days of the conference, coming from places between Atlantic Canada, Virginia, and beyond.
A presentation at the 2018 National Shellfisheries Association annual meeting was made on the project, to an audience of approximately 70 individuals.
A presentation by Morse and Cowperthwaite was given at the 2018 US/Japan Natural Resources Panel (UJNR) Panel on aquaculture, in Mystic Ct, to an audience of 25; mostly scientists from both the US and Japan.
The project was included in a presentation at the 2017 International Pectinid Workshop, in Portland, Maine, to an audience of approximately 75 scallop experts from around the world, with several Maine producers and fishermen present as well.
– The lines set out at the DMC, the Clark’s Cove site and the Atwood site have themselves become very important for education and outreach – they are materials for hands-on, applied learning about this method of scallop farming and aquaculture in general. For example, the scallops on the Damariscotta have been used by several students in the current Sea Grant-funded aquaculture training project Aquaculture in Shared Waters; for students involved in the UMaine course Applied Techniques in Shellfish Farming (at Darling Center, taught by Dr. Chris Davis), and for individuals not associated with either program, but interested in shellfish production. The scallops at the Atwood site have been integral to the outreach to commercial fishermen in that area, including being helpful to members of the first aquaculture cooperative to be developed in the state of Maine. All lines have been seen by our Japanese colleague Mr. Hiroaki Sugiyama, owner of Mutsu Kaden Tokki Co; his company manufactures ear-hanging equipment, and we all have benefitted from his visits to these sites. It is hard to overstate the value of having the lines from this project available for interested parties to observe, handle and learn from.