OOA Progress Report for the period 1/01/01 through 12/31/01

Principal Investigator: Richard Langan

Accomplishments
Scheduled Tasks:

1. Refine methods for seed handling, socking and harvest of rope cultured mussels
2. Evaluate the potential for offshore suspension culture of sea scallops
3. Compare mussel growth rates and production cycles with other mussel culture operations in the US and Canada
4. Assess potential advantages of integrated aquaculture activities
5. Transfer technologies to the user community

1. The major advances over the past year were the implementation of continuous socking technology (Figure 1) and the design and construction of harvesting equipment (Figures 2 and 3) that can be used for stripping seed from collection ropes as well as harvesting market size mussels from the growout ropes. The continuous socking equipment was purchased from a grower in Maine while the harvesting machine was designed by the project team with assistance from a project consultant (John Bonardelli). The harvester consists of a ramp, a hopper with a mussel stripper and a hydraulic hauler attached to the back end. The equipment is capable of harvesting 100 meters of seed line or growout rope in ten minutes.
2. Sea scallop culture was initiated in April 2001. Fifteen spat collectors (Figure 4) that were deployed in Pennobscott Bay by the Stonington Fishermen's Alliance in September 2000 were delivered to the project in April 2001. Spat bags were stripped of scallop seed at the UNH Coastal Marine Laboratory, and the seed counted, measured and placed in appropriate mesh size pearl nets (Figure 5). The nets were initially deployed at an inshore location prior to deployment offshore. The fifteen collectors yielded approximately 60,000 scallop seed that ranged in size from 2 mm to 10 mm (Figure 6). The seed were graded into two size classes (> 10 mm and < 10mm) in June 2001 and were deployed from the offshore longline in strings of 5 to 7 nets. Scallops were sampled and measured periodically between June and December. Seed were graded and thinned on four occasions during the period. Growth was highly variable and averaged approximately 1mm per week (Figure 7). The seed of the largest size at deployment grew to > 50 mm by December 2001 (Figure 8).
3. Growth for two cohorts of mussel seed was monitored throughout the period (Figure 9). The seed deployed in June 2000 grew from 25 mm to 74 mm in 12 months and reached market size of 55 mm in 8 months of growout. These seed were socked at a density of 220 mussels per foot and yielded approximately 8 lbs. of market sized mussels per foot. Seed deployed in December 2001 using the continuous socking method grew from 22 mm to 66 mm in 12 months. This cohort was socked a higher density (320/ft) had slower growth by comparison with the June 2000 cohort (Figure 10). These growth rates compare very favorably with those reported for the Northeast US and Atlantic Canada. In addition, the ability to initiate two production cycles per year (spring and fall seed collections) results in having uniform sized product available all months of the year.
4. During 2001, only small numbers of fish, and therefore only a small amount of feed was used in finfish culture operations. With such a small amount of organic matter (relative to what was naturally occurring in the water column), it was not possible to estimate the contribution of uneaten fish feed to mussel diet. While the benefits true polyculture may be difficult to determine in the open ocean, it may be possible to balance inputs of nitrogen (N), carbon (C) and phosphorus (P) from finfish operations with removal of N, C and P using marine plant and bivalve culture.
5. Technology transfer activities consisted of presentations at local, regional and national meeting, and conferences, and posting of project progress on the project website (http://ooa.unh.edu). Five presentations on the shellfish culture component of the project were made in 2001. Additional technology transfer activities are planned as soon a s sale of the mussels is sanctioned through State of NH and US FDA agreement.

Important Results or Findings
As reported above, the results of 2001 project activities as reported above indicates that the potential for commercially viable mussel culture in offshore environments is high. While growth rates for sea scallops are favorable, issues such as those reported in Section D below may affect commercial viability.

Difficulties Encountered
Difficulties experienced over the past year include continued problems with submerged floatation, difficulties hauling a fully loaded longline, fouling by hydroids and for the first time since the project commenced, predation by sea ducks. As described in last year's report, many of the 16" plastic submersible floats manufactured in Canada collapsed at the working depths used in the project and resulted in the longline sinking to the bottom. A British Colombia, CA vendor of plastic floats from China was identified and several floats were purchased in June 2001. Though these floats claimed to have a working depth of 100 m, all the floats failed at a depth of 20 m (Figure 11). Several stainless steel beer kegs were acquired in November 2001 from the Red Hook Brewery in Portsmouth, NH. Buoyancy was measured at 115 lbs., and pressure testing will be conducted in early 2002. We continue to seek other manufacturers and distributors of submersible floatation.

In June of 2001, when the June 2000 seed were market size, the fishing boat outfitted to tend the longline experienced some difficulty in lifting the line. We calculated that even at approximately 75% capacity on the line, the weight of mussels and fouling was approximately 18,000 lbs. Fully loaded, the weight would exceed 25,000 lbs. While the longline could probably handle that amount of production, it is unlikely that a 40ft fishing vessel as equipped for the project ca safely tend more than 15,000 lbs. per line. A specialized vessel such as a catamaran (60-80 ft) that can haul and tend along the centerline would be needed to handle full production weights.

Hydroid fouling was heavy in 2001, however, besides adding additional weight to the line, no real problems were encountered.

During a trip to the longlines in September 2001, a flock of sea ducks was observed swimming in the vicinity of the vessel while the longline was at the surface for tending. On a return trip to the site several weeks later, a flock of 50-60 ducks was rafted immediately above the longline and left only when disturbed by the approach of the vessel. When the line was raised to the surface, it was obvious that the ducks had stripped a large quantity of mussels from some lines, in some cases reducing the diameter of the mussels from six to four inches or less. The ducks were identified as female and/or immature common eiders, a species that is common in winter at the Isles of Shoals and known to prey on small mussels. They were not immediately identified on the September trip because there were no adult males with the distinctive black and white plumage. While eiders have been present at the Isles of Shoals all years of the project, this is the first year in three in which we had encountered duck predation. We speculate that while the ducks would not be normally be looking for mussels well offshore in deep water, the flock that happened to be in the area when the line (and mussels) were at the surface, discovered the presence of the longline and did their damage over a period of several weeks. No additional predation or ducks were observed in the vicinity of the longline after late October 2001.

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

In summer and early fall, pearl nets became completely fouled with hydroids in a little as three weeks (Figure 12). In addition to reduced flow and food availability for the scallops, the hydroids added a great deal of weight to the lines that had to be compensated for by additional buoys. Fouling by mussel seed resulted in clumps of scallops that were heavily byssed to the nets and had to be separated by hand. The handling required to remove mussels, as well as the handling when thinning and grading scallops, required a great deal of labor and resulted in scallop mortalities.

Anticipated Success in Meeting Project Objectives in Scheduled Project Period Expectations for the commercial success of mussel culture remain very high, however, we have far less optimism for the commercial viability of suspension culture of sea scallops due to problems cited above.

Reports, Manuscripts, and Presentations Resulting from the Project Report
Oral presentations on offshore shellfish culture were given at:

1. Aquaculture America 2001 in Orlando Florida, Jan 2001
2. Annual OOA Investigator's meeting in Portsmouth, NH Jan 2001
3. A special meeting of NH regulators and legislators in April 2001
4. OOA IV in St. Andrews New Brunswick, CA in June 2001
5. A special meeting of the Coastal Conservation Association in October 2001

Tasks and activities for next reporting period

Tasks for the next reporting period
Tasks identified for the next two-year period include refinement of materials, equipment, husbandry and technology transfer as follows: Materials

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

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

1. Determine the effect of seed stocking density on growth and condition index of mussels
2. 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
3. Evaluate the performance (growth and condition index) of seed from different sources
4. Continue to evaluate the growth and culture potential of sea scallops
5. Continue to produce commercial quantities of mussels

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

Work plan to accomplish tasks
Materials Evaluation

1. We will evaluate the strength of byssal attachment of seed mussels on Canadian "fuzz" rope and New Zealand "Christmas tree" rope by socking equal samples of the two types of rope at different densities.
2. We will identify, purchase and evaluate the performance at depth of commercially available floats and beer kegs.

1. The continuous-style socking machine owned by the project proved to be cumbersome and potentially dangerous due to the height of the seed hopper (76 inches high). We will redesign the socking machine such that the seed hopper is no higher than 40 inches.

1. The effects of stocking density will be evaluated by measuring growth and meat yield of mussels grown at different densities
2. Seed collector lines will be deployed from the longlines every two weeks from May through October for each year of the project and monitored monthly for mussel density and growth. Density, growth and fouling will be used to determine whether three seed collection periods are possible, and which months produce optimal results for annual production cycles.
3. Mussel seed from three sources (New Hampshire, Blue Hill Bay, ME and Rhode Island Sound) will be graded to equivalent size, seeded at equal densities and monitored monthly for growth and meat yield throughout a complete growout period.
4. Sea scallop seed (Placopecten magellanicus), which were deployed in pearl nets from the longline in the spring of 2001, will be measured monthly for shell height throughout the project period to determine growth rates and culture potential at open ocean sites. Mortality will also be determined.
5. One longline will be committed to full-scale mussel production for each of the next two years of the project. Density, growth and condition index will be monitored monthly for each growout cycle.

1. Information on all aspects of offshore mussel culture including supplies and materials, methods, equipment, husbandry techniques, and production cycles will be made available to fishermen, scientists, resource managers, regulators and the general public through written reports, articles in trade journals, presentations at workshops, conferences and meetings, web available text, images and video, and manuscripts published in the scientific literature.

Concerns or difficulties
None anticipated

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