HomeMy WebLinkAboutDraft_Selldorff_Shellfish_Rev02
Shellfish Habitat Assessment Report
To: Town of Barnstable Conservation
Commissioners
From: Pamela Neubert, Megalodon
Environmental LLC
Conservation Commission Administrator P.O. Box 329 Woods Hole MA 02543
File: Selldorff - 102 Bluff Point Drive, Cotuit Date: October 19, 2022
Megalodon Environmental LLC (Megalodon), performed two shellfish habitat assessments at the launch and recovery
location of an amphibious vehicle located adjacent to 102 Bluff Point Drive, Cotuit, Massachusetts (Figure 1). The
surveys occurred in June and September of 2022. The purpose of the study is to document the shellfish abundance in
and around the area of the amphibious vehicle. The project is within the estuarine waters of Cotuit Bay. This area is
surrounded by year round and seasonal residential development.
The study location is within an area determined by Massachusetts Division of Marine Fisheries (MADMF) to be
approved for shellfish growing and suitable habitat for quahogs (Mercenaria mercenaria) and soft shell clams (Mya
arenaria) (Figures 2 and 3). Massachusetts Department of Environmental Protection (MADEP) has not mapped
eelgrass (Zostera marina) in the Project area.
The shellfish surveys provide a description of the shellfish resources at the proposed amphibious vehicle launch and
recovery location. This information will assist the Conservation Commission and other regulatory agencies with their
responsibility to protect the Town of Cotuit beachfront resources. The resource areas within 100 feet of the project
site include: land under the ocean, land containing shellfish, coastal bank and land subject to coastal storm flowage.
Survey Methodology
Megalodon’s survey methodology followed a process of interfacing with the Town of Barnstable Shellfish Warden
(Amy Croteau) to perform shellfish assessment surveys that were approved by the Town to determine the potential
impact of a single amphibious vehicle to a specific shellfish species Mya arenaria (soft shell clams). Soft shell clams
are found within intertidal beach areas in Cotuit and the Town’s concern that prompted this shellfish assessment
study was to determine if the weight of the amphibious vehicle was significantly and negatively impacting soft shell
clams that may occupy the area where the amphibious vehicle is operated.
Shellfish stations at the Project location were arranged in a grid pattern (Figures 4 through 7). The study included
surveying the area along transects perpendicular to the shoreline within the area that is typically utilized by the
transiting amphibious vehicle from its parked location to a water depth that allows for its use by floating as well as
areas that served as control locations in regions of the beachfront that are not utilized by the transiting amphibious
vehicles. A centerline transect that was perpendicular to the beach in the area most often used by the amphibious
vehicle for transiting was established. Additional transects were established also perpendicular to the beach at 50
and 150-ft. on either side of the proposed transiting area. Samples were approximately 1-cubic foot of substrate and
processed through a 0.25-inch mesh basket at each of the station locations. General sediment texture, shellfish
abundance, and other observations were recorded (Figures 4 through 7) for June and September 2022.
Figure 1. Shellfish survey area, 102 Bluff Point Drive, Cotuit, Massachusetts.
Figure 2. MADMF Shellfish Suitability.(October, 2022).
Proposed Project
Location
Figure 3. MADMF Shellfish Growing Areas (October , 2022).
Proposed Project
Location
Figure 4. Sediment type within Survey Area 102 Bluff Point Drive, Cotuit, Massachusetts June 2022.
Figure 5. Shellfish abundance within Survey Area, 102 Bluff Point Drive, Cotuit, Massachusetts June 2022
Figure 6. Sediment type within Survey Area 102 Bluff Point Drive, Cotuit, Massachusetts September 2022.
Figure 7. Shellfish abundance within Survey Area, 102 Bluff Point Drive, Cotuit, Massachusetts September 2022
Survey Results
Megalodon’s survey found no eelgrass within the project area, which was consistent with MADEP findings within
the MassGIS MassMapper website. In both surveys the project area consisted of coarse to fine sand based on
visual inspection. (Figure 4 and 6). In June 2022 a total of thirty two (32) quahogs and two (2) whelks were
identified (Figure 5). In September 2022 a total of thirty seven (37) quahogs and 3 softshell clams were identified
(Figure 7). Similar numbers of quahogs were found throughout the sampled area, including the centerline where
the amphibious vehicle routinely transits. The presence of multiple quahog (Mercenaria mercenaria) individuals
suggested that the amphibious vehicle is not having a significant negative impact to this shellfish species.
Soft shell clams, which were the target species of this shellfish study, were only found during the September
survey with a low number collected (3 individuals). The soft shell clams were identified well outside the area that
is frequently used for the amphibious vehicle transits from the upper intertidal into open water. Additionally, shell
hash or broken shell fragments from soft shell clams were not observed within the amphibious vehicle transit lane
or on either side of the transit lane out to 150 meters. From Megalodon survey results, it appeared that soft shell
clams were not commonly present in the study area. Accordingly, there is no evidence of any significant negative
impact to soft shell clams in the area where the vehicle is commonly used.
Conclusions and Literature Review
There is a paucity of data available that investigates the potential impacts from amphibious or other vehicles that
utilize the shoreline or beachfront areas for recreational purposes and there is no study available that investigates
the impact of five or fewer vehicles that use the beach areas for recreational purposes. Shalacher and Thompson
(2007) studied the potential impact of offroad vehicles (ORV) to sandy beaches. Their conclusions were that
activities for ORV had less impact in the lower sandy intertidal beach area where the sediment was compact and
easier to drive than on the upper beach areas where vehicle driving could damage coastal dunes. Their study
observed beaches with numerous vehicles (in some cases 500 vehicles) and the impact to the sandy beach habitat
was not quantifiable. The only other study found in Megalodon’s literature review for determining potential
impacts of amphibious vehicles (or other vehicles) to soft shell clams was a study performed by Taylor et al. (2012).
In this study, New Zealand sandy beaches were sampled from areas that receive numerous offroad vehicles as well
as horse riding activities. The beaches studied were heavily used by offroad vehicles with hundreds of vehicles
utilizing the beachfront per day. They concluded that determining impacts from recreational vehicle use was
complex and to protect shellfish resources applying several management strategies over utilizing a single strategy
may be more effective to protect shellfish and other natural resources inhabiting the beach where recreational
vehicles are used. Management strategies suggested by Taylor et al. (2013) included permitting a zoned area for
vehicle use, implementing short-term, time of year restrictions to coordinate with peak shellfish spawning time to
allow shellfish to settle, and vehicle speed restrictions. They also reported that the shallow subtidal area had
lower potential for impact to shellfish resources when compared to the intertidal area as the shallow subtidal area
was not as frequently transited by recreational vehicles. Therefore, permitting measures were not as necessary for
shallow subtidal habitat.
There is no study that could be found by Megalodon that investigates the impact of one amphibious vehicle to
intertidal and shallow subtidal beachfront area. Based upon the limited literature currently available and our on-
site study results, we conclude that the use of the amphibious vehicle is not having significant, negative impact to
soft shell clam abundances in or around the transiting area and it does not have an effect to quahog abundances in
the shallow subtidal.
Literature Cited:
Taylor, G.F., Marsden, I.F. and Hart, D.E., 2012. Management of vehicle and horse users on sand
beaches: Implications for shellfish populations.
Schlacher, T.A. and Thompson, L.M., 2007. Exposure of fauna to off-road vehicle (ORV) traffic on sandy
beaches. Coastal Management, 35(5), pp.567-583.
Please do not hesitate to contact me if you have any questions.
Sincerely yours,
Pamela Neubert, Ph.D.
Principal
Megalodon Environmental, LLC
megalodonev@gmail.com