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

Principal Investigator: Larry G. Harris

I. Accomplishments

A. Scheduled Tasks:
There were three major efforts scheduled for the first year of the study:

1. production of juvenile urchins for caging studies in a hatchery system under development
2. continuation of a long term natural recruitment study and
3. growth studies comparing suspended and bottom based caging systems.

B. Progress on Tasks:

1. Juvenile Production: Cultivation of larval sea urchins through metamorphosis was successful for the third year in a row. Testing of a new phytoplankton species, Tetraselmis sp., showed that larval urchins were not able to digest it and reversion to a diet of Isochrysis and Duneliella was needed to produce viable juvenile urchins. We now have five year classes (1998 through 2002) in culture for growth and cultivation studies. The 2002 production was over 300,000 juveniles.
   
2. Juvenile Recruitment: Recruitment studies begun in 1983 were continued with collectors set out at sites from Eastport, Maine to the Isles of Shoals, New Hampshire from May through July. Analysis of results is continuing, but the decline in recruitment that has paralleled declining harvests appears to have stabilized over the last two years. Actual recruitment in the southeastern portion of the Gulf of Maine has declined to almost no replacement due to intensive crab predation.
   
3. Growth Studies: A variety of growth studies involving suspended and benthic cages have been conducted over the spring and summer months and are continuing. The initial phase of the studies was to compare growth and survival of urchins placed above and below the summer thermocline at the fish pen site south of the Isles of Shoals with cages placed at similar depths on the bottom at both the Isles of Shoals and at a sea urchin lease site in Portsmouth Harbor. Two sets of cages were lost at the fish pen site due to mechanical failures and a third trial is currently underway.
   The cages placed in the Portsmouth Harbor lease site and above and below the thermocline (25 and 45 ft respectively) provided interesting and somewhat unexpected results. The temperature from Hobo recorders on the cages show a pattern of higher temperatures in Portsmouth Harbor and some stratification by depth at the shallow and deep Isles of Shoals sites (Figure 1). Growth rates were highest at the shallow Isles of Shoals site and lowest in Portsmouth Harbor. It was anticipated that growth and survival would be highest below the thermocline at the Shoals site, but both were much higher above the thermocline (Figure 2). It appears that greater water motion from surge above the thermocline had a greater impact on growth than the slightly lower temperatures below the thermocline. Crab predation was a greater problem in the deep cages and explains the high mortality in those cages. Wire mesh envelopes were also deployed near the Coastal Marine Laboratory to look at growth rates and mortality for juvenile urchins. The initial results gave comparable growth rates to the animals in the caging studies of 40 to 60% increase in test diameter over about four months. Modification of the envelope design is currently underway and we will be greatly expanding our studies with juvenile growth in the coming year. The most significant result utilizing the envelope system occurred in one deployed in early June 2002. Twenty-five juvenile urchins were added to the cage in June and 46 urchins were present in October. Growth rate for all animals was 55%, which included some individuals that were smaller than the original cohort of animals. The mean growth rate for the 25 largest animals was 112%. It appears that suspended envelopes deployed through the recruitment period promote both active growth and act as recruitment sites for settling larvae, which is unlikely to happen in benthic cages where crabs are present. We will be focusing much of our effort in the coming year to test the feasibility of utilizing suspended mesh cages to promote both growth and recruitment of young urchins.

C. Important Results or Findings
The most important results to date have been to (1) continue progress on the hatchery system to produce juvenile urchins and also (2) test the feasibility of suspended cages for juvenile grow out of urchins for out planting to aquaculture lease sites. We are refining our larval culture system and have expanded it to almost commercial production capacity for the winter, 2003 culture period. The field growth studies have demonstrated that juvenile grow out is possible and that suspended cages show more promise for both growth and survival than benthic cages. In addition, it appears that suspended cages may function to promote growth of hatchery-reared juveniles as expected and also to increase production through natural recruitment.

D. Difficulties Encountered
It was anticipated that wave surge would be a problem with the offshore fish pens and in the winter months at the Isles of Shoals sites. Wave surge did cause problems for the cage systems deployed at the fish pens, but the size of the cages was likely a factor. Future efforts will be focusing on smaller envelope systems that should be less impacted by surge.

E. Anticipated Success in Meeting Project Objectives in the Scheduled Project Period:
This was the first year of the project and some setbacks did occur with a species of algae tested for larval cultivation and with efforts to deploy caging experiments on the fish pens. We were successful in producing two sets of juvenile urchins and have expanded our capabilities for much greater capacity in the second year of the project. The initial growth trials with difference cage designs and comparisons of suspended versus benthic cage deployment have provided us with encouraging growth results and confirmation that a suspended cage deployment has the greatest potential for commercial applicability in sea urchin aquaculture.

F. Reports, manuscripts, and presentations resulting from the project
We will be presenting results from our current studies at Sea Urchin 2003, Sea Urchin Conference, Puerto Varas, Chile in March 2003. Additional manuscripts are also being prepared on juvenile growth.

II. Tasks and activities for next reporting period

A. Tasks for the next reporting period:
There are three major tasks to be undertaken in the second year of the project.

1. Larval cultivation will be standardized for the production of juvenile urchins at near commercial scale (millions).
2. Suspended caging studies with juvenile urchins are underway and will be greatly expanded.
3. Winter out planting experiments with small urchins will be conducted to measure growth and survival at two sea urchin aquaculture lease sites.

B. Brief work plan to accomplish tasks
The hatchery in the basement of Portsmouth Scuba has been renovated to hold eight 300L vats for larval culture and algal cultures are underway. Initial spawning is expected to begin in January and larval cultivation will continue until May 2003. Cage-based growth studies are underway and a greatly expanded effort is planned to begin in the spring utilizing juveniles produced in the hatchery. Greater efforts to utilize the fish pens for suspended cage testing are in preparation. Winter deployment will be attempted, but most of the effort will begin in April. Cohorts of small (10 to 20mm test diameter) urchins will be out planted at sea urchin lease sites in Portsmouth Harbor to monitor growth and survival over the year. The animals will be placed in cobble habitats where only large urchins now occur and monitored at two-month intervals.

C. Anticipated concerns or difficulties
There are a number of aspects to working in the offshore environment that involve trial and error. The offshore fish pens offer a great opportunity for testing caging systems for juvenile grow out for sea urchin aquaculture. We do not anticipate greater than normal problems associated with working offshore and look forward to the coming year of studies.

III. Expenditures
The expenses have been within the range anticipated for the work accomplished so far and that planned for the near future.