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

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

Summary

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.

Objectives/Performance Targets

Principal targets in this period were to:

1. Seed 5 shellfish farms and one research farm with ear-hung scallops
2. Visit deployment sites to make observations on growth rate, mortality, water temperature, fouling and other operational considerations.
3. Deploy alternative spat collection materials, to evaluate effectiveness and profitability
4. Begin to track labor and equipment costs
5. Create a project web page for hosting details on the effort

Accomplishments/Milestones

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.

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.

2. 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. Spat collectors were set by Nate Perry and Edward Perry, on 22 September, 2016, and later on, in October. Four lines of 12 collectors each were deployed. Each line was paired with a ‘control’ line that the Perry’s will use for their own production; the pairs were set out as endlines to an anchor, and the anchors were connected via a groundline. This arrangement has been found to ensure better holding power, and to facilitate better retrieval success. Each line contained three depth strata (high, medium low) and each stratum had each of the experimental collection materials (1/6” mesh, ¼” mesh and ½” mesh) as well as the control material, called Netron. These collectors will remain deployed until April-June at which point they will be retrieved and examined for their collection effectiveness.

4. 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.

5. A project web page has been created for this project, at

http://www.seagrant.umaine.edu/extension/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.

Impacts and Contributions/Outcomes

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.

– 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.

Collaborators: