CFF researchers conduct ongoing studies at-sea and in the lab to understand fishing gear interactions and improve gear design and testing. Our research has contributed to improved fishing practices, the reduction of catch of non-target species, the development of equitable and sustainable fishing regulations and protection of endangered species.

Development of an extended link apron and determining selectivity characteristics using a dredge cover net
Principal investigators: Farrell Davis, Ricky Alexander and Liese Siemann

Funding provided by: NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program

Since 2016, CFF has been developing and field-testing a dredge apron with extended links in both the horizontal and vertical direction (two-way apron) and in only the vertical direction. The traditional apron configuration for a scallop dredge consists of 4-inch rings connected by two links side-by-side. While the two-way apron is effective in reducing the relative catch of small scallops and flatfish, the catch of larger scallops is also impacted to a lesser degree. CFF researchers hypothesized that an apron using extended links only in the vertical direction could achieve the same conservation objectives while still maintaining catch of larger scallops.


Preliminary testing of the vertical extended link apron indicates this hypothesis is valid, however, a more comprehensive understanding of the non-target species efficiency of the one-way extended link apron is needed for an accurate assessment of this modification’s impact on flatfish bycatch and mortality in the scallop fishery. The current project evaluates this by using a dredge cover net. Results from the project are providing greater insight about the impacts of implementing the one-way extended link apron.

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Testing of a low-profile scallop dredge (LPD) for bycatch reduction via field testing and computational fluid dynamics (CFD)

Principal investigators: Farrell Davis and Liese Siemann

Funding provided by:  Commercial Fisheries Research Foundation, NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program; NOAA/NMFS Saltonstall Kennedy Grant Program.

This ongoing investigation addresses the ongoing issue of reducing flatfish bycatch.  In 2011, CFF designed variations of dredges that had a lower height or profile than the standard scallop dredge. hypothesized that this reduced height made it easier for flatfish to swim over the dredge’s frame. Testing of these low-profile dredges (LPDs) on commercial scallop vessels in the Limited Access (LA) fleet and the Limited Access General Category (LAGC)[MN1]  fleet showed the LPDs either did not reduce bycatch, or reduced it with a significant, unacceptable loss in scallop catch. Because of the reduced scallop catch, CFF scientists hypothesized the lowered height of the LPD, which had reduced the depressor plate angle of 22.5º rather than 45º typical of commercial dredges, was changing the fluid dynamics of the dredge, and thus the ability to capture scallops.

To test this hypothesis, CFF contracted with Memorial University to run computational fluid dynamics (CFD) simulations of the flow of water around the original LPD and a new version with a 45º depressor plate. Results from the CFD modelling demonstrated that the original LPD failed to generate the complex flow believed to facilitate the capture of scallops, while the LPD design with a standard depressor plate angle did generate a complex flow that was comparable to standard dredges. A new frame was built based on this analysis. Field testing of the newly redesigned frame in 2015 indicated that its scallop catch increased to commercially acceptable levels but that the efficiency was being affected. CFF again employed CFD analysis, this time in-house, coupled with flume tank testing at Memorial University using a set of dredge frames and dredge bag scaled to 1/6th of the standard dredge. These scale models can be used in flume tanks at scaled speeds that match speeds used in the commercial scallop fishery. Flow pattern results from the flume tank tests and CFD simulations indicate that the simulation results are comparable to flume tank results. [MN2] CFD analysis and flume tank testing both suggest that turbulence behind the redesigned LPD might contribute to its lower efficiency relative to the standard-height frames. Current research focuses on increasing the LPD dredge efficiency through two potential avenues: 1) reducing the turbulent flow by modelling a range of depressor plate sizes and angles, and 2) testing redesigned dredge bags on CFF’s scaled dredge frames at Memorial University.

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Testing selectivity and raised webbing gillnets on target and non-target species in the northeast haddock fishery

Principal investigator: Jason Clermont

Funding provided by:  Bycatch Reduction Engineering Program

Working with local groundfish gillnet fishermen, CFF is testing the effect of mesh size and raised webbing on selectivity and bycatch rates. Through our combination of field sampling and in situ video and data recording, we are identifying optimal gear configurations, mortality and depredation rates of haddock and bycatch species. We are also characterizing factors that influence gillnet catch and retention efficiency with the aim of improving efficiency and reducing bycatch in the Georges Bank haddock (Melanogrammus aeglefinus) fishery.


A modified flounder sweep for flatfish bycatch reduction in the LA and LAGC scallop fishery

Principal Investigators: Ricky Alexander, Chris Parkins and Farrell Davis 

Funding provided by NOAA/NMFS Bycatch Reduction Engineering Program and NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program

The initial phase of this project tested the use of a flounder cookie sweep (FCS) to deter flatfishes from entering the dredge and thus reducing bycatch. Initial testing of the design in the Limited Access General Catgory (LAGC) fleet indicates that despite high variability in trends, the FCS is largely successful in reducing undesirable bycatch and filtering out sub-commercial size scallops in the LAGC fishery. Current research is focused on a FCS featuring various-sized rubber cookies that, together, create a vibration shown to induce upward swimming in flatfish when attached to a trawl net. 


Development of ecosystem friendly scallop dredge

Principal Investigators: Farrell Davis, Liese Siemann, and Melissa Campbell

Funding Provided by: NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program


The goal of the project is to develop an alternative gear design to reduce the impact of fishing effort on pre-recruit scallops. The project will utilize six 7-day research trips to test an extended link apron, adding two consecutive links between the 4 inch rings in the vertical and horizontal direction. Extended link design increases inter-ring spacing of the apron encouraging the mechanical sorting of pre-recruit scallops. Gear testing will take place in the Mid-Atlantic and Nantucket Lightship scallop rotational access areas, particularly in areas with high abundances of harvestable scallops found in combination with pre-recruit scallops.

Development and testing of an inexpensive GPS radio buoy system for early notification of whale entanglements
Principal investigators: Liese Siemann,  Samir Patel, and Farrell Davis 
Funding provided by: Marine Mammal Commission and CFF

Protected species of whales continue to be caught regularly in the vertical buoy lines of bottom-set pots and gill nets of commercial fishers. Current regulations to mitigate these entanglements, primarily through the use of weak links, have had limited success, and entanglements are increasing worldwide. Fishing gear modifications may eventually reduce entanglements to low levels, but more immediate solutions are needed to protect critically endangered species like the North Atlantic right whale.

In response, CFF is developing and testing an inexpensive, GPS radio buoy system that provides early notification of marine mammal entanglements in the vertical buoy lines of commercial fishing gear.


Using inexpensive parts and open source technology, CFF's "bsBuoy" system provides fishers with a readily available, rapid notification system to identify entanglement events. The technology has the potential to reduce to response times of rescue crews and thus improve the  frequency and outcomes of disentanglement efforts. Additional uses for this technology are currently being explored.


Determination of the impacts of dredge speed on bycatch reduction and scallop selectivity

Principal investigators: Farrell Davis, Christopher Parkins and Liese Siemann - Coonamessett Farm Foundation, Inc (CFF) David Rudders, Virginia Institute of Marine Sciences (VIMS)

Funding provided by:  NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program

Estimating incidental mortality in the sea scallop fishery

Principal investigators: Liese Siemann, Carl Huntsberger, Jasper Leavitt, Farrell Davis, and Christopher Parkins, Ron Smolowitz

Funding provided by:  NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program


Relative efficiency of a Coonamessett Farm Turtle Excluder Dredge equipped with escape windows

Principal investigators: Farrell Davis and Christopher Parkins

Funding provided by:  NOAA/NMFS Bycatch Reduction Engineering Program and NOAA/NMFS Atlantic Sea Scallop Research Set-Aside Program

Determining the catch efficiency of a caple sorting grid in the summer flounder trawl fishery

Principal investigators: Christopher Perkins and Ron Smolowitz

Funding provided by:  NOAA, NMFS, NEFC

Improving a scallop dredge bag to reduce fish bycatch using flume tank testing
and computational fluid dynamics

Principal investigators: Liese Siemann and Farrell Davis

Funding provided by:  NOAA Scallop Research Set-Aside