Hurricane Island's GSI Project

Written by Madison Maier, Aquaculture Manager

Madison underwater! Photo by Carl Huntsberger

Even though I work on a scallop farm, I don’t get scallop dinners any night I want them.  After all, you can’t eat your research project! 

GSI, or gonadosomatic index, is the ratio of gonad mass to total body mass (Langton et al. 1987).  I find out what these masses are by shucking a scallop, then weighing everything but the shell and then weighing just the scallop’s reproductive organ, the gonad.  For our scallops (P. magellanicus), GSI are a proven way to determine when spawning happens.  Their gonad is self-contained and the follicles are retained after spawning; so the majority of weight differences before and after spawning can be attributed to the presence or expulsion of gametes (Langton et al. 1987).  So, if we take GSIs every week, we can see as the gonad becomes a bigger proportion of the scallop’s total body weight.  After they spawn, and release their eggs and sperm, the gonad becomes a much smaller proportion.  In order to see this difference, regular sampling is required!  

Research team descending to collect wild scallops.

Each week, we conduct GSIs on 45 scallops from our farm, 25 scallops from farms in North Haven and Stonington, and have a special license from the DMR to take wild scallops as well!  Most of the farmed scallops are being grown in lantern nets 10-30 feet below the surface of the water.  On our farm we’re also growing scallops in bottom cages, so we can actually compare this between gear types, and we collect wild scallops at depths between 30-80 feet while scuba diving.  With all of this data, we can compare spawning times of farmed and wild scallops as well as spawning times of scallops at different sites within the Penobscot Bay.  

So, stay tuned as we collect more data over the summer to help us understand this important process on farms and in the wild scallop population! 

GSI prep! All of these scallops are waiting to be weighed. Female scallops have an orange/red gonad, while male scallops have a white gonad.

Madison lives out her dream of becoming a ribbon dancer...underwater. Filmed in Penobscot Bay off the shore of Hurricane Island.

Scallop Tagging Study

Written by Phoebe Jekielek, Director of Programs and Research

Greetings from the Island!! We are missing the “normal” hustle and bustle of students, teachers, bird banders, first responders, visitors and the broader community as a whole out here on the Island. BUT, there is a lot that has been happening in the research and facilities worlds and we are still hustling. The scallops are still growing, on our farm and in the wild, and some of our research is helping to better understand how that looks in the wild population.

In Spring 2019, we received Maine Sea Grant Program Development funds to conduct a scallop tagging study in collaboration with Maine Department of Marine Resources. This tag-recapture study will improve area-specific growth rate models to inform and assess rotational management strategies and to specifically address DMR research priorities. This study will provide spatially explicit growth information, help identify areas for closures and enhancement, and shine light on the scale of movement, the potential for exchange of scallops between management areas, and potential size ranges at which scallops are less likely to disperse away from an enhanced area. Learn more about how Maine manages the wild scallop fishery here.

We worked with local wild scallop harvesters to identify ideal areas for collection around Hurricane Island and communicated with our local lobster fishing industry, the second largest in the state, to have as little impact on the benthos and surrounding lobster fishing activity. Once the scallops arrived on the Hurricane dock, we drilled a 0.8mm hole in the corner of the right hinge on the top side of the scallop shell using a Dremel tool with a tungsten carbide tip in a drill press. We then threaded a 0.6 mm wire with a labeled tag through this hole and recorded the tag number, shell height, and shell width. Each tag was printed with the tag number and DMR contact phone number.

We tagged and measured 800 scallops in the Lower Penobscot Bay rotational closed area and then redeployed them. The hope is that, when caught again during the scallop season in the Lower Penobscot Bay management area, the tag number, catch location, and shells will be returned to us by fishermen so that we can better understand scallop movement and growth in the rotational closed areas. The shells will be sent to DMR to record the same measurements, shell height and width, that we collected this Spring. We are growing 200 tagged scallops in our aquaculture site as a comparison for growth and to understand tag retention and mortality.

A very important part of this effort was working with local wild scallop harvesters and the local Vinalhaven community, it would not have been possible without their support, knowledge, and assistance. THANK YOU!! Now we just have to wait for 1.5 years, the next open scallop season in our rotational management area, to collect the rest of our data. Stay tuned!!

Social Distancing with Scallops

Written by Carl Huntsberger, Research Assistant

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Me with one of our scallop cages that needs to be sorted and cleaned.

This week marks the end of my first month of the 2020 research season on Hurricane Island, and what a great month it has been! Despite the challenges of the COVID-19 crisis the research team has been lucky enough to be able to continue our projects on the island while taking necessary precautions to keep us all safe. Hurricane Island has a research aquaculture lease site which is largely dedicated to projects focused on providing more information to improve scallop aquaculture. Along with other growers and institutions, we’re involved in projects monitoring growth rates in different gear types and water quality on our farm and others. We’re also monitoring potential gear effects on the timing of spawning events and, as part of the Maine eDNA Project, working with the University of Maine and Bigelow Laboratories to develop how we might use eDNA (environmental DNA) as a tool for monitoring both wild and farmed scallop populations. More on that in future blogs.

As the scallops grow they become crowded in the aquaculture gear, reducing their feeding ability and increases their stress, resulting in slower growth. Thus, each spring we clean the cages holding the scallops and move some to new cages giving them room for appropriate social distancing. Allowing the scallops room to feed and move freely not only improves their general health, it also reduces the risk of direct transmission of any diseases present. In my previous position at Coonamessett Farm Foundation, I was part of the team which monitored the wild population of scallops on Georges Bank for signs of disease or stress. The disease we had identified in the scallops poses no risk for consumption but decrease the quality of the scallop, either making the scallop unmarketable or significantly reducing the price and taste. There is no evidence of this phenomenon at our site that we are aware of, but this year we will start careful monitoring of the scallop meat quality during our existing spawning data collection. I actually developed the method we’ll be using to evaluate meat quality (Pic #2) and look forward to using it on Hurricane!

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Examples of the range of scallop meat quality found on Georges Bank with normal scallops on the left and poor quality scallops on the right. We will be using a similar scale to evaluate the condition of the scallops at our site.

While lower densities of scallops improves their growth in the gear, the high densities on farms overall makes them great potential spawning locations, with the possibility of enhancing wild populations of scallops. Early observations from a pilot study on the Hurricane Island site suggest that scallops grown in bottom cages on our site are spawning sooner than scallops grown in lantern nets. This difference might allow the juvenile scallops a longer growing season before the winter, potentially improving their chances of survival. These are some of the other questions we’re exploring in our research. Again, more on that later, so stay tuned for more information, results from our projects, and more about our aquaculture site. We would love to hear from you with any questions or words of wisdom!

Fall 2019 Research Team Update – By the Numbers!

Written by Jessie Batchelder, Aquaculture Manager

I think the entire Hurricane Island staff would agree with the statement, “it’s been a crazy summer on the island”. Crazy busy, crazy productive, crazy stressful, but also crazy fun. It’s been an awesome ride, and as the crisp dry air blowing through my window this morning and whitecaps dancing across the sound reminded me, fall is here. While the season is far from over and there’s plenty more work to do, it’s a nice moment to look back on the summer and highlight a few things that the research team has accomplished. 

Spat bags that were built with the help of a Bowdoin College Class of 2023 orientation group

7128: scallops that are currently being grown in bottom cages and lantern nets out at our newly approved 3.2 acre lease site off of Gibbons point. 

22: spat bags that were sorted through, largely with the help of students! You can read more about our spat bags and baby scallops in Madison’s blog.

3142: baby scallops that were collected from the spat bags! In the next few weeks these baby scallops will be transferred out to the farm where they will continue to grow over the winter.

156: spat bags built with a Bowdoin College orientation group which will be deployed later this month around Hurricane Island to collect scallop spat for next year.

Snorkeling with a sunfish

1: new research boat that provides a better work space, can haul lots of gear out to the farm, and goes fast! 

400: milliliters of 6 mm oyster seed that we are now growing in addition to our scallops and kelp.

180: scallops that have been dissected this summer as part of our work with gonadosomatic indices (GSI’s). GSI’s are a calculation of gonad mass as a proportion of the total body mass. As scallops become ready to spawn, the GSI increases. Since the beginning of July, we’ve dissected 20 scallops each week to see how the GSI’s have changed as we near scallop spawning season. You can read more about scallop GSI’s here or here.

How much gear do 4 divers need?

3757.81: grams of scallop gonads that were weighed this summer for our GSI work. And still more to come!

13: phytoplankton samples that Madison and Hallie analyzed as part of the Department of Marine Resources phytoplankton monitoring program. This program identifies toxic phytoplankton species to help inform the closures of shellfish harvesting areas.

1: spontaneous snorkel with a sunfish in between dives. What else would you do when you’re on your surface interval and see a sunfish swim by? 

3: lost moorings found by our dive team in the mooring field. 

Our amazing 2019 Research Team!

10: scallop dive transects completed, 6 still to go! Read more about our scallop dive transects in Flora’s blog.  

29.5: cumulative hours that our dive team spent underwater this summer.

5: incredible hard working women on the research team! In the 3 seasons I’ve worked for Hurricane the research team has always been an all women team, but this is the biggest team we’ve had ever had and it shows in all the work we accomplished this summer!

Everybody Loves Baby Scallops: Combining Education and Research

Written by research assistant, Madison Maier

There is something about Hurricane Island that lingers in a visitor’s memory.  It’s an easy job to create a place that people are fascinated by; the island itself does all of the heavy lifting.  The staff borrows this power of place and incorporates it into curriculum. It is not an original idea but it is an incredibly effective one.  Placed-based educational theory is based on connecting students and curriculum to their local ecological, cultural, and historical contexts and emphasizes ‘real world’ learning experiences.  In short, our curriculum is hands-on and community-based (Sobel 2005).  

For the research team, our bridge to form these connections to our unique place on a Maine island is our spat, or young scallops.  Scallops are broadcast spawners, meaning that the eggs are fertilized in the water column.  Then, the new scallop spends its larval stage floating in the water column, their travel dictated by the currents in the spawning area (Hart and Chute 2004).  Successful scallops will settle down on hard substrates, like rocks. Some scallops, however, settle out into our spat bags, set out in the water column specifically to collect them.  

Spat bags are simple devices, a mesh bag filled with a hard substrate that is suitable for scallop settlement.  While in their larval stage, scallops can flow through the mesh bag, but once they settle on the inner substrate, they grow too large to escape.  Of course, scallops aren’t the only things settling in these bags.  

Our research team and program participants collaborate to sort through the spat bags, pulling out any small scallops that we find.  At this point in their life cycle, the scallops have the distinctive shape of the curved shell, with two ‘ears’ on one end, just miniaturized. I like to have an ongoing challenge of trying to find the smallest scallop in each spat bag.  We’ve found some that are only about a millimeter in height, which is the same as the thickness of a driver’s license! After we’ve sorted through the entire bag, we count each individual scallop that we found. This data helps us to know the best places to put our spat bags to collect scallops, and can be telling about the health of scallop populations in that area. 

At some point in this process, I like to pull out an older scallop that started as spat we collected and has been grown in our aquaculture gear.  The student’s work in sorting through spat bags is invaluable to our aquaculture farm and research because these are the next generation of scallops that we will study and grow.  Our spat is the link that encourages collaboration between our participants, the Hurricane Island community, the local economy, and the environment. And, small scallops are really cute.  

Hart D. R., and A. S. Chute. 2004. Sea Scallop, Placopecten magellanicus, Life History and Habitat Characteristics.

Sobel, D. 2005. Place-Based Education: Connecting Classrooms & Communities (2nd ed.). The Orion Society.

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