UNH Atlantic Marine Aquaculture Center: Publications

Demonstration of Technology and Methods for Open Ocean Aquaculture of Molluscan Shellfish in New England

CINEMar/Open Ocean Aquaculture Annual Progress Report for the period 1/01/02 through 12/31/02

Principal Investigator: Richard Langan

I. Accomplishments

A. Scheduled Tasks:
Tasks identified period included refinement of materials, equipment, husbandry and technology transfer as follows:
Materials

Evaluate the performance of two different types of core ropes, with particular attention to the strength of byssal attachment at different densities
Evaluate the effectiveness and cost of several buoyancy options for submerged longlines

Equipment

Improve the design of the Canadian continuous socking machine for operational effectiveness and safety.

Husbandry

Determine the effect of seed stocking density on growth and condition index of mussels
Develop a seed collection strategy consisting of three seed collections (spring, summer, fall) and evaluate the relative length growout period for the three annual cohorts
Evaluate the performance (growth and condition index) of seed from different sources
Continue to evaluate the growth and culture potential of sea scallops
Continue to produce commercial quantities of mussels

Technology Transfer

Transfer information on optimal materials, equipment and husbandry methods to the regional commercial fishing community

B. Progress on Tasks
Materials

Five different growout ropes were identified and sourced from suppliers and in New Zealand (2), Norway (2) and Canada (1) (see Figure 1). One of the ropes, a Norwegian netcord, was determined to be unsuitable for use with the continuous socking machine and was not used in the byssal attachment growout trials. A minimum of seven replicate 30' lengths of each of the four rope types were seeded in December 2002. Byssal attachment will be determined by comparing the initial seeding density of each type of rope with the density at market size. Several 6" to 1' samples will be taken monthly beginning in January 2003. Based on the results of these trials, recommendations will be made on the optimal growout rope.
Following some successful but operationally impractical experimentation with propane tanks and beer kegs, a Canadian company that manufactures a thick-walled, rotationally-molded buoy by a was identified and a number of buoys were purchased. The buoys cost $6.50 USD, and are therefore quite affordable for mussel culture. They are 16" in diameter and provide approximately 72 lbs. of buoyancy. The manufacturer claims the buoys have a working depth of 40 meters. A number of buoys were deployed on the longlines in the fall of 2002 and they will be evaluated throughout the 2002 cohort growout cycle.

Equipment

The height of the seed hopper component of the continuous socking machine was reduced by 24 inches and a washdown manifold was added to aid with seed flow. The original machine and the adjusted version are shown in Figures 2 and 3.

Husbandry

Analysis of meat yields and growth rates at different densities indicated that neither meat yield nor growth was affected at densities up to 220 mussels per foot (Figure 4). Mussels socked at densities of 300 per grew somewhat slower but meat yield was not affected. Mussels grown at higher densities did, however, tend to slough off the growout rope when the line was lifted to the surface. We estimated up to 10% loss of mussels on high density ropes during harvest operations.
Three seed collector lines were be deployed from the longlines every three weeks from May through late November and monitored monthly for mussel settlement and fouling. The array consisted of two 30' and one 60' lengths of rope. Based on preliminary analysis, the some mussel set was observed throughout the period, within the highest density observed in late June. Fouling by hydroids affected all collector ropes and created difficulties with seed sorting. The 2002 seed settlement evaluation did not support the possibility of a third major settlement period and production cycle. It should be noted, however, that 2001-2002 was an unusual year, with heavy sets reported in December 2001 by the project's fouling community study, and a large overset of mussels on buoys and line in March. This was the first time since 1999 that we observed mussel set during those times. The ropes were also inspected to determine the maximum settlement depth of mussels at the site. The longline to which the ropes were attached was maintained at a depth of 30' from the surface during the evaluation period. The upper parts of all ropes showed higher densities and virtually no mussel set was observed beyond 20' (55' from the surface)
Mussel seed from the New Hampshire offshore site and from Blue Hill Bay, ME were seeded onto growout ropes in the late fall of 2002. NH seed was much smaller (20 mm) than the Maine seed (29 mm) therefore direct growth comparisons will not be possible. Growth rates (mm/month), however, will be monitored throughout the growout cycle.
Sea scallop seed (Placopecten magellanicus), which were deployed in pearl nets from the longline in the spring of 2001, were measured monthly for shell height throughout the project period. Figure 5 shows scallop growth from deployment in 2001 through November 2002. The frequent thinning required to maintain scallops at low density resulted in handling mortalities during the first year of growth, however, once the scallops reached 35 mm shell height, they fared much better and mortalities were very low (< 2%). Some mortality associated with mussel seed attachment to individual scallops and virtual entombment in byssal threads was observed.
Mussel growout to market size was carried out on one half of one longline and approximately 1/3 of a second line. Growth rates of the two cohorts harvested during 2002 are shown, along with all cohorts produced since 1999, in Figure 6. Harvest of the seed deployed for growout in December 2000 was delayed until March 2002 while waiting for the USFDA to approve NH's growing waters application for certification. Approximately 5,000 lbs. of mussels were harvested in March and April 2002 from this cohort using the custom designed and built mussel harvesting machine (Figure 7). Mussels were processed and packaged by Great Eastern Mussel Farms. Great Eastern sold the bulk of the mussels and returned a portion to NH for distribution to area markets and restaurants. Mussels seeded to growout ropes in December 2001 were harvested September through November 2002. Several hundred pounds were harvested pounds at a time, processed and packaged on the harvest vessel. These mussels were distributed locally under the brand name "Isles of Shoals Supremes" (Figure 8) to restaurants and markets. A market survey was distributed with the mussels (Appendix I, See below) and results are being tabulated. Approximately 3,000 lbs. were harvested from the in the fall of 2002.

Technology Transfer

Information on all aspects of the offshore mussel project was made available to a variety of audiences through presentations, demonstrations, panel discussions, written reports, abstracts and manuscripts. Reports, project updates, photos and videos are posted on the project website (http://ooa.unh.edu). Presentation venues ranged from meetings with local fishermen to invited talks at international conferences. A series of meetings with the Portsmouth and Yankee (Seabrook) fishing cooperatives has led to the identification by the fishermen of two large areas off the NH coast where offshore farms would not interfere with commercial capture fishing activities. An individual has been identified who, along with the mussel project team, will assist individual fishermen and/or cooperatives with site selection and permitting.
The mussel project team had valuable technology exchange via e-mail, meetings and site visits with representatives of the mussel industries in the US, Spain and New Zealand. A number of countries are confronting a shortage of space for expansion for surface-referenced culture and are interested in the UNH-developed technology for submerged culture in exposed waters. While growers in several countries have deployed surface longlines in some exposed sites, the UNH project is currently the only submerged mussel operation in the open ocean. Valuable information on growing ropes, buoys, moorings and mechanization was gained by the project though the exchange of ideas.

C. Important Results or Findings

The growth and product quality has been consistently good since the throughout the growout of five seed cohorts since 1999.
New buoys and a better understanding of the growth rates (increased weight burden on the longline) has led to better maintenance of line depth, fewer imploded buoys and fewer operational difficulties.
Larval settlement can vary a great deal from year to year and better monitoring of larval presence settlement would be an important component of a commercial mussel industry. Growers and seed suppliers need to be prepared to take advantage of good sets that may occur at different times of the year. Settlement, though quite consistent over the long term, may be locally or regionally dependent on water temperatures. The set in December 2001 was likely due to the to the warm temperatures in the fall and early winter. An unusual phytoplankton bloom also occurred in December 2001 and coupled with the warm temperatures may have affected gamete production and release. The March set may also have been the result of faster warming of surface waters in early 2002,
The excellent meat yield of the mussels is due to some extent to the very thin shells. While we have been aware of this for several years, this year’s harvest and processing by Great Eastern Mussels Farms resulted in a very high percentage of shell breakage (>40%). Great Eastern only processes bottom-grown mussels at their plant in Tenant’s Harbor, Maine and their customary product handling and machinery are a bit rough on thin-shelled, rope-cultured mussels. The appropriate handling procedures and machinery would need to be implemented to process large quantities of mussels with minimum product loss through breakage.
Mussel were distributed directly to eight restaurants in the Portsmouth area, and to an additional six restaurants by a local wholsaler/retailer who also sold them at his retail establishment. Response from consumers was excellentr, and most respondents expressed a preference for open ocean mussels to the cultured mussels they currently buy from Canada.

D. Difficulties Encountered
Mussel culture
Difficulties experienced over the past year included hauling the weight of a fully loaded longline, fouling by hydroids, and temporally variable seed settlement. Discussions with mussel growers from New Zealand combined with personal experience with a 40' fishing vessel have led us to believe that for greater efficiency and maximum production, a specialized vessel such as a catamaran (60-80 ft) that can haul and tend along the centerline would be needed.

Hydroid fouling of seed lines was problematic in 2002, adding additional weight to the line, and creating seed grading difficulties. This was exacerbated by the unusual timing and sporadic nature of spat settlement, which, due to lower percent cover by mussel spat, provides more attachment surface for hydroids to become established.

Sea scallops
Problems encountered with sea scallop culture included fouling of pearl nets by hydroids and mussels, and labor associated with changing nets, grading and reducing densities

E. Anticipated Success in Meeting Project Objectives in the Scheduled Project Period
Expectations for the commercial success of mussel culture remain very high, however, more attention needs to be directed toward the timing of mussel spat settlement.
Because of the labor associated with suspension culture of sea scallops, the vast majority of the scallops were bottom seeded when the reached approximately 50 mm shell height. The seeded area will be surveyed in the spring of 2003 to determine the viability of bottom culture.

F. Reports, manuscripts, and presentations resulting from the project
Oral presentations on offshore shellfish culture were given at:

Aquaculture America 2002 in San Diego, CA Jan 2002
A meeting of the Northeast Shellfish Sanitation Association (NESSA) in Manchester, NH, June 2002
First International Mussel Forum at Aquaculture Canada, 2002, Charlottetown, PEI, CA. September 2002
Korean-US Symposium on offshore aquaculture in Honolulu, HI in October 2002
US-Japan Council on Natural Resources (UJNR) in Yokohama, Japan, October 2002

Abstracts :
Aquaculture America 2002
Aquaculture Canada 2002
21st UJNR Symposium
2002 NESSA Meeting

Manucsripts:
Langan, R. 2002. Balancing Marine Aquaculture Inputs and Extraction: Combined Culture of Finfish and Bivalve Molluscs in the Open Ocean. Journal of the National Fisheries Institute of Japan. 2002.

II. Tasks and activities for next reporting period

A. Tasks for the next reporting period

Continue with materials evaluation
Continue with recruitment (spat settlement) studies
Continue technology transfer with local fishing community
Continue to work with international mussel industries on advancing offshore culture technologies
Continue mussel production and marketing

B. Workplan to Accomplish tasks

Buoys evaluation will be done by documenting performance during normal operations and by mooring buoys at depth (> 100') for extended periods. The strength of byssal attachment to growing ropes will be evaluated as described in section I.
Seed line deployment will continue at bi-weekly intervals throughout the year.
The project team will provide technical assistance to the local fishing industry for permitting, equipment and materials acquisition, longline construction and deployment and husbandry techniques.
The project team will maintain contact with New Zealand, Spanish and Canadian industries to exchange ideas and technology on longline design and vessel configuration (see Figure 9).
The project will
Continue to produce mussels and work with local restaurants and seafood markets on brand recognition and promotion.

C. Concerns or difficulties
None anticipated

III. Expenditures
Expenditures were consistent with original plans and timeline for the project

Appendix I. Consumer Survey

Isles of Shoals Supreme Mussels

Customer Survey
Thank you for agreeing to serve Isles of Shoals Supreme mussels in your restaurant or market. Shoals Supremes are rope cultured mussels grown in the pristine offshore waters of the Gulf of Maine and are produced as part of a comprehensive effort by the University of New Hampshire to develop viable offshore aquaculture in the Northeast. As our coastal populations increase, the nearshore waters and embayments are subjected to competing uses and increased pollution. Therefore, offshore waters represent the only opportunity for growth in cultured seafood production. UNH, along with several New England Research Institutions, the local fishing community and marine industry partners has embarked upon this exploration of the “New Frontier “of aquaculture.

In addition to developing the biological and engineering capabilities to move finfish and shellfish culture offshore, we are also very interested in the economics of offshore operations. A component of the economics is market reaction to the seafood we produce. We would appreciate it if you could take the time to answer a few questions for us.

Please mail or fax your completed survey to:
Richard Langan, Project Director
Environmental Technology Building, UNH
35 Colovos Road
Durham, NH 03824
Fax 603-862-2940

From the Kitchen:

1) How would you compare the appearance of the uncooked product to the mussels you currently purchase and serve?