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Alaska Department of Fish and Game


Mariculture
Intertidal Geoduck Clam Mortality Study

ADF&G Southerly Intertidal Geoduck Clam Seed Plantings

The department believes that intertidal geoduck clam farming may help facilitate the expansion of the mariculture industry in Alaska. Therefore, in addition to the work Tom Manning is doing at the northern range of the geoduck clam, the mariculture section acquired a Fish Resource and Transport Permit for an experiment to examine survival of small geoduck clam seed (6 millimeters) during the winter in the intertidal zone at a southernmost location in Alaska.

In September, the Southeast Regional Resource Development Biologist, Flip Pryor, and contractors Tom Carruth and Dale Stanley, picked up small geoduck clam seed that had been shipped from the Qutekcak Hatchery, and traveled aboard the FV Sable to a site 60 miles south of Ketchikan. They planted three geoduck clam seed in each of three groups of 27 four-inch diameter PVC pipes at the -1 foot Mean Lower Low Water (MLLW) tidal elevation, then again at the 0 foot MLLW tidal elevation as the tide was coming in, and finally at the -2 foot MLLW, with divers, for a total of 729 geoduck seed planted in 243 PVC pipes. Each PVC pipe had a piece of 1/4" predator net stretched over the open end, held in place with a heavy duty rubber band.

Staff and contractors were concerned about the effect that tidal surge, logs moving through the area at high tide, and seaweed and kelp washing up on the beach would have on the project. They noted that six pipes were washed out of one plot with the tide change and determined that the rocky soil kept the pipes from being properly seated. They replaced and reseeded that plot. They were also concerned that some seed may have washed out through the 1/4" mesh.

Tom Carruth checked the site when he was in the area participating in a commercial fishery near the end of the year. He observed that many tubes at the highest elevation of plantings had been knocked out by logs. Staff will check the site for cleaning and maintenance in the Spring of 2004.

At the end of the first year of study, the animals from six of the twenty-seven tubes in each group of nine will be checked for survival and the animals will be measured for growth. A first year analysis will include an evaluation of survivability based on tidal elevation and events of extreme weather. The department plans to monitor this project for five years.

Oyster Growth Study

The department issued a Fish Resource and Transport Permit to Sea Culture of Alaska for a mariculture research project in Chernofski Harbor, on the northwest corner of Unalaska Island, to explore the potential of the area for oyster culture. Growth trials were conducted at the Tanadgusix dock located directly across from Mutton Cove, near Observatory Point. Four hundred twenty-six oyster spat that averaged 24.1 millimeters in length were placed in wire mesh trays suspended from the dock on July 12, 2003. On October 3, 2003, three hundred twenty-nine live oyster spat averaged just 25.2 millimeters in length. One millimeter of growth over twelve weeks is extraordinarily slow for Pacific oysters.Rock Scallop Growth Study.

The department issued a Fish Resource, Acquisition and Transport Permit to Sea Culture of Alaska to acquire rock scallops, Crassadoma gigantea, from oyster culture gear within the Southeast Alaska drift zone at Port Althorp, transport some scallops to other areas in the Southeast Alaska drift zone, and transport others to the Central and Westward Alaska drift zones, for growth studies. The permit also allowed the placement of spat collectors in Port Althorp, in Southeast Alaska, Hawkins Island, near Cordova, and Chernofsky Harbor, on Unalaska Island, for the acquisition of indigenous rock scallops for future growth and studies.

The scallops in the oyster gear at Port Althop concentrated in a few nets, encompassing only a small swatch of the longline grid. Study participants collected 100 scallops in the 12-30 millimeter range, 260 scallops in the 31-39 millimeter range and 555 scallops in the 40-76 millimeter range.

One hundred-eighty scallops in the 12-39 millimeter range were shipped to Chernofsky Harbor and one hundred-eighty scallops in the 12-19 millimeter range were shipped to Hawkins Island. The remaining 555 scallops in the 40-76 millimeter range were shipped to Kosciusko Bay in Southeast Alaska. The transport to the Aleutians failed when all 180 scallops died during transit. Nine scallops died during transit to Hawkins Island and the rest were gaping upon arrival. After a month long recovery period in which there was no growth noted, the Hawkins Island scallops grew 12 millimeters in three months. The average growth of 4 millimeters per month compares to an average monthly growth rate at Kosciusko Bay of 5.3 millimeters.

The largest scallops were transferred from Port Althorp to Kosciusko Bay with two mortalities and no stress noted, and averaged 17.2 millimeters of growth over the four-month period, compared to the 11.39 millimeters recorded at Hawkins Island. Spat collectors were deployed at Port Althorp, Hawkins Island and in Chernofsky Harbor. The collectors at those locations will be retrieved and the contents examined during 2004.

Abalone Growth and Reproduction Study

The department issued Greg Clark, of Fisherman’s Harbor Ocean Products, a Fish Resource Permit to collect 48 adult pinto abalone, Haliotis kamtschatkana, and hold them alive in land-based tanks at Cape Pole for observation, conditioning and spawning. Greg also held a permit that allowed him to collect kelp.

Greg worked with known abalone expert, Carl Demetropoulos, to develop the project. Johnny and Myra Pugh and Kevin Dau of Kahli Cove Shellfish and Jon Agosti from the Qutekcak Shellfish Hatchery in Seward participated with Greg on the project. They worked drying kelp on racks then compacting it into bales, building tanks and a water conditioning unit, building the tumble culture system for Palmaria spp., recording project progress with a video camera, converting it into a powerpoint presentation and acquiring funding for the project.

The group was successful getting the animals to spawn. Greg Clark’s experiment has been delayed as he has been missing since January 22, 2004, the date his 32 foot boat grounded and broke up on rocks northwest of Prince of Wales Island. John and Myra Pugh and Kevin Dau plan to continue working on this project.