Frenchman Bay: Clam seeding and clam flat resiliency

Contacts

Joe Porada – Frenchman Bay Regional Shellfish Committee
acadiabaysclamandoyster@gmail.com

Mark Whiting – Hancock County Soil and Water Conservation District
mark.c.whiting@gmx.com

short project summary (PDF)

BAckground

The Frenchman Bay Regional Shellfish Committee (FBRSC) formed in 2010 in response to intensive harvesting on local flats during red-tide closures. The shellfish ordinance covers seven towns—Ellsworth, Franklin, Hancock, Lamoine, Sorrento, Sullivan, and Trenton—which span the bay from Bar Harbor to the Schoodic Peninsula.

Nursery net project sites at Marlboro Beach, Lamoine and Settler’s Landing, Hancock

Clam seeding

FBRSC is several years into a partnership with the Hancock County Soil & Water Conservation District (HCSWCD) focused on enhancing clam harvests on Frenchman Bay mudflats.

Early efforts involved directly seeding the flats with the goal of enhancing clam populations. However, the hatchery spat struggled to survive the first year. The group also experimented with clam seed recruitment boxes with mixed results.

Starting in 2020, FBRSC purchased seeds from the Downeast Institute and grew them on the flats under 5 ft. by 14 ft. mesh nursery nets designed by Joe Porada and created by clammers. The nets are inspired by “Beal Boxes,” but are able to hold more clams, and can be placed at the bottom of the water column. At the end of the season, the juvenile clams were overwintered in a lobster pound at the Downeast Institute in floating oyster bags. These older, viable clams were then transplanted into recently harvested flats and covered with predator exclusion nets, which proved mostly effective in shielding the clams from crabs and gulls. At the end of the second growing season, the nets were removed.

In 2021, the Shellfish Committee replicated the experiment with quahog seed on two study sites at Marlboro Beach, Lamoine and Settler’s Landing in Hancock. The nets were damaged, and mortality was high.

This netting project led to two successful seasons seeding clam spat, although scalability remains a challenge. FBRSC recognized the importance of maintaining the breeding population of large, wild clams, and in a similar vein to Maine’s lobster law, moved to protect clams over four inches in length, which have greater reproductive potential.

Harvesters were hired for project management and data acquisition work, a decision which increased the equity of the project and directly engaged clammers in the management and conservation of their resource.

ongoing projects

The 610 Project is an initiative to reopen 610 acres of closed clam flats in Frenchman Bay. The project aims to build capacity for opening flats by improving communication, and identifying and fixing pollution sources. Through collaborations with DMR, DEP, and the towns, project partners made progress in opening more than 70% of the acres that were closed at the start of the project. They also used Microbial Source Tracking (MST) to identify sources of contamination and worked with UMaine scientists to understand tidal patterns that were influencing continued closures in Egypt Bay and in the western part of Frenchman Bay.

Through the Green Crab Control Project, FBRSC trapped green crabs in certain coves, measured the impact of this trapping, and researched marked-based options for green crab control, such as participating in live-markets, supplying processing facilities, or providing suppliers with chitin from green crab shells.

takeaways

Clam survival was best in low intertidal habitat
The current approach to seeding, netting, and using recruitment boxes may be too labor intensive for large scale application
FBRSC had difficulty completing the work with volunteer conservation hours; it may be necessary to hire people for the most labor-intensive work
This work may have an aquaculture application, but few members are interested in aquaculture projects
The FBRSC will continue to hire local harvesters
FBRSC will explore the direct seeding of quahog spat in future research
An area of future opportunity could be mentorship to encourage a younger generation of clammers

The FBRSC is two years into a successful—albeit labor intensive—seeding project, and over a decade into ongoing shellfish sustainability work. FBRSC benefits from regional partnerships and the support of the seven communities that make up the shellfish ordinance, but managing the mudflats of Frenchman Bay is no small task. As a next step, FBRSC hopes to test the idea that establishing large reproductive clams will provide the natural spat needed to keep flats productive, especially in heavily harvested areas.

timeline

2011

FBRSC and Frenchman Bay Partners create the 610 Project and apply for funding
2011-2012

Groups collaborate on a conservation action plan for Frenchman Bay

Frenchman Bay Partners work with AmeriCorps volunteer Emma Fox to develop an economic report on the impacts of closed clam flats
2013

An agreement between clammers and mussel harvesters leads to the first
Intertidal Mussel Ordinance in the state

FBRSC received funding for 610 Project
2014

FBRSC received funding to survey and trap green crabs and continue the 610 Project
2016-2017

Jordan River becomes key an area of concern due to declining water quality
2018

Hancock County Soil & Water Conservation District and Frenchman Bay Regional Shellfish Committee begin exploring ways to sustain soft-shell clam harvests
2019

FBRSC used hatchery spat to seed harvested clam flats and accelerate recovery, and conducted Beal Box experiments

Hancock County Soil & Water Conservation District received funding for pollution tracking in Jordan River and Egypt Bay
2020-2021

Two-year nursery net experiment