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Placopecten magellanicus

In 2009, DEI received a grant from the National Marine Fisheries Service - Saltonstall Kennedy program - to undertake research to examine methods to enhance local (coastal) stocks using wild and/or cultured juveniles.

Please click on this link to read the Grant Proposal.

 

First Progress Report (15 December 2010)

Second Progress Report (11 April 2011)

Third Progress Report (1 December 2011)

Fourth Progress Report (7 June 2012)

Fifth Progress Report (16 December 2012)

Sixth Progress Report (29 June 2013)

Seventh Progress Report (29 December 2013)

Eighth Progress Report (29 June 2014)

Ninth Progress Report (2 August 2014)

 

Please click on this link to read the Final Report.

 The project began in July 2010 with the construction of a "boreal culture room" at DEI for the purpose of conditioning sea scallop broodstock and rearing larvae and juveniles.

The room was fully insulated and was designed to keep room and seawater temperatures below 50oF (10oC).

A chilling unit was installed with an ability to keep temperatures within +/- 2oF.

Two larval culture tanks (500 gallons) plus a 300-gallon juvenile and broodstock holding tank were the first to be used in the new room.

The first project involved collecting wild sea scallop juveniles, and was initiated in August 2010.

A series of five spat bags (2 mm aperture) were tied to a single line that was anchored by a cinder block filled with cement.

With the help of Rock Alley, we set out five sets of lines at 10 shallow water sites (< 20 m) and 10 deep water sites (> 25 m) around the Western Bay off Great Wass Island (town of Beals, Maine).

All five hundred bags (100 cement blocks and lines) were loaded onto the Miss Carmen.

Here is one set of five bags attached to a single line.

Each bag was stuffed with a piece of NETRON, a plastic, flexible mesh that helps increase the surface area of the bag and potentially gives scallop spat more surface upon which to attach during its settlement phase.

Lines getting ready to set.

Bags were thrown overboard first, then the cement block anchors.

The position of each of the 100 lines were recorded according to the data from Rock Alley's GPS unit.

The lines were left in the ocean all fall and winter, and were retrieved on 29 April 2011

In April 2011, we collected only 245 (49%) of the bags we had deployed the previous year.  Winter storms and other factors led to the disappearance of the rest of the gear.  Here, a juvenile scallop is measured with digital calipers.  All scallops from each bag were counted and measured.

The contents of some bags were taken to DEI to be processed.  Here, Cody Jourdet is spraying scallops off a piece of NETRON that had been stuffed inside a spat bag.

Each bag on a line was given a tag to identify the location of the line, the line number at each location, and the position of the bag on the particular line.

Unfortunately, the average number of sea scallop juveniles per bag was less than 10, hardly worthwhile from a commercial perspective if the goal is to produce hundreds of thousands or millions for stock enhancement enterprises.  Here, the NETRON is fouled with a species of jingle shell (*Anomia*) that was very common in many of the spat bags.

Given that wild scallop spat procurement did not seem a feasible enterprise (for this project and for a similar scallop project funded through the Northeast Consortium - see our "Sea Scallop Restoration" page - we focused our attention on culturing sea scallops for stock enhancement purposes.  In this photo, we are trying to induce adult scallops to spawn by placing them from seawater that was around 55oF into water that was close to 68oF.  Thermal shocking often times stimulates bivalves to spawn, and is a standard technique used at DEI to induce spawning in most bivalve speceis we culture.

Sometimes, it is not possible to collect well-conditioned broodstock from the wild.  Therefore, we developed a regimen of feeding adult scallops with several species of cultured microalgae and, with decreasing and gradually increasing seawater temperatures, we were successful in getting sea scallops to spawn just about any time of year we wanted.  Typically, sea scallops spawn in the late summer or early fall.

Scallop larvae typically take between 25-35 days to metamorphose and become juveniles.  This photomicrograph was taken by Kyle Pepperman and it shows a healthy, 20-day old sea scallop larvae with fully-developed larval shell and a full gut of digested cultured microalgae.  Photo taken on 29 December 2012.

Photomicrograph of recently metamorphosed sea scallop juveniles.  Animals are around 200 microns in shell length. Photo taken by Kyle Pepperman.

Two videos are available showing recently metamorphosed sea scallops.  Both videos were taken by Kyle Pepperman.  Link to Video 1Link to Video 2.

Although we tried numerous methods over a two-and-a-half year period to produce large numbers of sea scallop juveniles for stock enhancement purposes, we were unable to repeat most of the trial results with any consistency.  Problems generally were encountered after Day 20 in the larval culture.  Here, we show several sea scallop juveniles that successfully settled onto NETRON material that we placed inside a culture tank.

Cultured sea scallops - Downeast Institute - June 2013. (Mesh in background is approximately 3 mm.)

 

 

 

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