It Takes a Village

Saving the Wild Soft-shell Clam

by Jessica Gribbon Joyce, Roger Stephenson, and Susie Arnold, Ph.D.

“Despite declines, the soft shell clam industry remained the third most valuable commercial fishery in the state at around $12 million in 2017. Using innovation and technology, along with harvester-collected data, and collaborations with DMR, shellfish dealers, citizen-scientists, and students, we can increase our knowledge of this resource and figure out how to best mitigate the population declines related to climate change and predation.” Fishermen’s Voice photo.

Recent media attention has been raising awareness around the precipitous decline in Maine soft-shell clam landings over the last five years as well as the declining trend in licenses over the last several decades. Over a five-year period from 2013 to 2017, landings decreased over 4 million pounds (from 11.3 to 6.9 million pounds). In just one year, from 2016 to 2017, the value declined $3.8 million. In 2017, the decline in landings was due in part to multiple harvest closures due to harmful algal blooms. Despite these trends, this industry remained the third most valuable commercial fishery in the state at around $12 million in 2017.1

While immediate causes for decline can vary locally throughout the State, the major causes for population decline are known. Clams are susceptible to predation by green crabs and milky ribbon worms2; ocean acidification and other impacts from a shifting climate are proving to be real threats.3 More frequent and stronger rain events (2” rain events in 24-hrs) biotoxins and closures due to poor water quality are hampering access to the resource.

Solutions to these issues have been proposed and tested by members of the softshell clam industry, the research community, and municipal and state managers. Conservation ideas range from collecting wild seed or buying cultivated clam seed and then planting it in the intertidal and protecting it with netting, to instituting rolling harvesting closures, and changing the minimum and/or maximum harvest sizes. Some of these measures have been implemented within a specific municipality; others in a shared, regional waterbody through collaborations between municipalities, schools, harvesters, nonprofits, and scientists. However, these measures are likely to continue on a small-scale until there is improved access to science-based practices, funding, and an increase in leadership and collaboration across diverse groups.

In contrast to these local and regional initiatives, there is one state-wide event that brings all these groups together on an annual basis, together with staff from the Maine Department of Marine Resources (DMR) and others: the Maine Fishermen’s Forum, an industry event and trade show held in late winter. Shellfish Focus Day (previously called Clam Day) during the Forum centers on wild and aquaculture bivalve shellfish and provides an opportunity to share updates on the latest in science, management, outreach, and education throughout the state.

This past March, volunteers organized a networking session at the end of Shellfish Focus Day to connect the stakeholder groups and discuss research and management needs in the fishery.

Some of the ideas that researchers, harvesters, and dealers raised during this session called for additional data collection and resource surveys to better inform conservation and management initiatives. Tim Sheehan, a shellfish dealer in Pembroke asserted that Maine could use more baseline data on the flats. “The diggers are the citizen-scientists out there each and every day,” Sheehan said. Using innovation and technology, along with harvester-collected data, and collaborations with DMR, shellfish dealers, citizen-scientists, and students, we can increase our knowledge of this resource and figure out how to best mitigate the population declines related to climate change and predation.

Gathering this type of information would build on the existing baseline of landings data (i.e. the volume of clams harvested and brought to market), which is currently the primary source of information used to track population declines. Using landings as a proxy for the status of clam populations is one indicator, though there are several other indicators that can be used in fisheries when assessing the status of the resource.

One of these indicators is a biological survey of the resource, which is done with scientists, industry members and other volunteers, generally utilizing a “quadrat”, or square tool, to count and measure the clams in a particular area. Some municipalities in Maine conduct these surveys with the members of their shellfish committees, license holders, shellfish wardens, and sometimes with support from DMR biologists or other researchers. Kohl Kanwit, Director of the DMR’s Bureau of Public Health, explained that “DMR is interested in seeing municipalities expand surveys of all the shellfish resources included in their respective ordinances because this basic information will enable more informed decisions on effective resource management strategies and license allocations.”

Another useful gauge, and where diggers can play an important role, is effort data, referred to as “Landings Per Unit Effort” or LPUE. LPUE provides finer resolution data to help understand how the number of people harvesting clams and days on the flats correlate with the volume landed in a particular area. Few towns are collecting this type of data; however, the Town of Biddeford represents one example in which this type of reporting is required. According to their ordinance, clammers are required to submit a monthly log including the date, location and number of bushels harvested during each day. Biddeford has also created a zone system for management and reporting.

For fisheries in general, collecting and analyzing these data sources is typically under the authority of a state and/or federal management agency. However, in the case of soft-shell clams, and several other species of bivalve shellfish in Maine, management is shared between the municipalities that have authority over their intertidal zone and DMR. Thus, collecting data and assessing the population size is also shared.

The municipal shellfish committees know their local resources and have a say in how many, when, and where clams are harvested in their ordinances, and the state provides overarching regulations, support from biologists, and water quality and biotoxin monitoring services to ensure clams are safe to eat. While there are benefits to this approach of co-management, there are also drawbacks.

Under good conditions and in the past, this “shared” management model has sustained the resource. However the rapidly changing environment today requires a heightened level of coordination and communication, and ready access to good data and their implications. Under these conditions the state and municipal bodies would improve their capacity to make more informed and timely decisions to adapt to the changes we are seeing, for example, an increase in predation by green crabs.

Recommendations that emerged at Shellfish Focus Day that the industry should consider building upon include 1) increasing coordination among municipalities and other partners in a shared watershed or region; 2) increasing coordination and collaborative data collection among industry members, municipalities, and DMR; 3) improving communication and training around proven research and management practices to conserve soft-shell clams; and 4) obtaining sufficient funding for continued research, through state, federal and private funding sources.

A growing number think we don’t take immediate steps on this call to action with wild clams, then we may need to look towards aquaculture methods to maintain access to this important species to our culture, ecosystem, and economy. The risk, as characterized by Bailey Bowden, a harvester from Penobscot is that “Our iconic boiled lobster with steamers dinner will soon be boiled lobster and raw oysters.”

1 Maine Department of Marine Resources: http://www.maine.gov/dmr/commercial-fishing/landings/documents/softshellclam.table.pdf

2 Brian F. Beal et al. Spatial Variability in Recruitment of an Infaunal Bivalve: Experimental Effects of Predator Exclusion on the Softshell Clam (Mya arenaria L.) along Three Tidal Estuaries in Southern Maine, USA, Journal of Shellfish Research (2018). Available: http://www.bioone.org/doi/abs/10.2983/035.037.0101

3 Green, Mark A. et. al. 2013. Carbonate mineral saturation state as the recruitment cue for settling bivalves in marine muds. Estuaries and Coasts 36: 18-27.*