Baby steps in sea scallop aquaculture

An admittedly optimistic (over)statement:
Mark your calendars, because June of 2012 will be the month that the sea scallop aquaculture industry got moving in Maine. 

This is not to say that other important work has not already been done in the state before: Tommy Pottle's work in Cobscook Bay, Schuyler Belle's polyculture project before that, and goodness knows how much other experimentation happened in the past too, and all contributed to today's understanding.  Please also note that in previous posts I've highlighted many other folks who have significant experience with sea scallops, and who have graciously and generously agreed to share that knowledge with me - and by extension, other prospective scallop farmers.   That's important, and not to be missed.  That said, I'm gonna bet exactly 25 cents that we've got a start now that will take the Maine scallop culture endeavor further along than it has been to date, and perhaps further along than anyone in the US.  Okay - that's the end of boastful statements.

And to be fair, all the work done by Maine fishermen and scientists since 2000; in spat collection and stock enhancement, allows us to be where we are now. I'll single out Capt. Marsden Brewer and former DMR scientist Dan Schick, as well as Leslie-Anne Davidson of DFO in Moncton as extra deserving of notice, but there's a bunch of other folks too.  That's a whole different story, and one certainly worth telling, but I'm going to skip to the item of today for the time being.

The other morning I met with Nate Perry and his father Ed; Ed's got over 30 years as a lobsterman, and his son started an oyster farm a few years ago.  Nate and I have known each other since, and he grows a nice oyster indeed - Pine Points he call them, grown in the speedy waters of the Scarborough River.  Nate's been interested in sea scallops for a while, and so he, his dad and his brother Ben (also a lobsterman) set out some spat collectors last fall, hoping to catch a few.

For those of you who aren't familiar with them, a spat collector for scallops is a mesh bag, with more mesh inside it - all made of polyethylene. The bag mesh is pretty small; best size seems to be about 1.5mm, and the mesh inside is larger and more rigid. When you put some of the stuffing into the bag, the bag ends up puffed up, like a pillow.  The bags get set on a single up-and-down line, and if you put them out in the right place and at the right time (September generally, in Maine), you end up with scallops.  What actually happens is that the scallop larvae float their way into the bag, and settle out onto the mesh stuffing.  Since the scallop larvae are about 450 microns (0.45mm), they can fit through the outer mesh, and once they begin to grow, they eventually can't get back out through the bag. Voila! Scallop seed.

One of the bags that Nate, Ed and Ben set, with an estimated 300+ juvenile scallops inside. Scallop size was good, bags were clean, and few competing settlers were found inside. Great to see!

A very nice collection of beautiful juvenile scallops, ready for stocking to cages

The seed we checked out was pretty good size, and the bags were not too fouled at all. Moreover, the catch was almost completely scallops; just a few jingle shells (Anomia simplex), and nary a starfish to be seen in the whole shebang.  That's good.

So now, with the help from some development $ from Maine Sea Grant for cages,  and collaborating with 11 or so fishermen and shellfish growers, we'll have scallops grown around the coast so that we can monitor growth and mortality. We'll also take a look at effects of density, and compare results from our different sites.

In addition - and this is really, REALLY important, the Maine Dept. of Marine Resources has pledged support for biotoxin testing during this project.  The goal is to understand the toxin loads from red tides, in the different tissues of the scallops.  The reason why this is so critical is that scallops can accumulate biotoxins in their tissues, easily enough to make a person sick, or dead.  The meat (or adductor muscle) - the part that we Americans generally eat - does NOT accumulate those toxins to any real extent, which is good for everyone. But, if we're going to develop aquaculture as a going concern, we'll have to look at selling products like roe-on scallops, whole or live scallops, etc...and there are plenty of chefs who would love to get their hands on some beautiful whole scallops. It's those other tissues that are problematic - they accumulate the toxins from certain algae, and they can hold on to it for a long time.  So - by gathering information on biotoxins at each site, we can begin to get a picture of toxicity, and to develop the important monitoring and testing programs that will help to ensure that safe product goes to market.

Here is an adult female scallop, with a full roe sac (bright red). While normal spawning season in Maine is in July, this photo was taken in January; the roe sac will condition either for a winter spawn, or as a mechanism to store energy - the true reason is unclear to me at this point. The roe is also a desired product in the market, but it and the other tissues can carry dangerous levels of biotoxins, so proper testing and monitoring is absolutely critical. 

The field data on growth, survival, density and all those other husbandry issues will be matched up with the data we gather regarding product safety, and eventually we'll have a leg up from where we've been this last many years.

Also, I spent a very nice morning (by which I mean poor weather but great company and enjoyable work) the other day with Marsden and his neighbor Bob, retrieving spat collectors that Marsden had set last September. We steamed from Stonington out to Isle au Haut, where he'd had the bags out of the way for overwintering, and went through the process of counting, seiving, and stocking some shellfish bags.  Marsden has been expert in collecting spat for many years now, and although the scallops were smaller than they've been in recent years, he was still in the 3000+ per bag area.  

The stuffing inside the collector bag provides a nice, clean substrate for scallop larvae to settle. They then grow too large to exit the bag, and are effectively captured. This photo is a pretty nice set of small scallops; other settlers include jingle shells (Anomia sp.) and a few rock borers (Hiatella arctica), but otherwise is quite clean, for having been deployed 9 months.

So. We now have a couple of sites with initial stocking to cages, with more to follow.  I'm so excited I can barely stand it. The next months will be telling, and I'm looking forward to more work with the fishermen, growers and the DMR staff as this little experiment runs its course.  Stay tuned, scallop lovers!