Atlantic Sea Scallop Dredge Design Challenge


Channa Comer

Urban Assembly Academy of History & Citizenship for Young Men, Bronx

Summer Research Program for Science Teachers

August 2011



Subject:  Biology

Grade Levels: 9-10

Introduction:  This is lesson number six in a series on sea scallops. In this lesson, student will be challenged to design a sea scallop dredge to collect scallops within a given set of constraints and conditions.  The lesson can be completed in five 50 minute periods. For the entire series, contact:




Per Class

·         Paper towel

·         Plastic tablecloths to cover tables


Per team     


Simulated ocean floor



*If your school has a firewall that prevents you from accessing You Tube videos, you can use any free video conversion site (like this one) to convert the video into and FLV file which can be opened on any video viewer installed on your computer.


The diagram below represents the engineering and/or design process. Teams do not follow a linear path from problem to solution, but rather weave in and out of conceptualizing, constructing and testing, and acquiring knowledge, all the while applying multiple skills and habits of mind of innovators. Through the Design Challenge process, students have the opportunity to build broad skills useful throughout their lives, regardless of the specifics of the challenge. In using this open-ended approach that leads to the creation of numerous designs, students are challenged to apply their domain knowledge, personal experiences, interests and talents to the process of creating an inventive, team driven solution. This approach creates a powerful learning experience, where students are intrinsically inspired to learn and have pride in achieving a goal as a team. In a traditional design approach, students would research before developing potential solutions. Your order will depend on the goal of the design challenge and your students.







Construct & Test

Acquire Knowledge

Sea Scallop Dredge

It is acknowledged by nearly everyone working on the ocean that fishing gear causes some alteration of the seabed, although the significance and duration of this alteration continues to be debated. In the absence of clear scientific evidence, qualitative rankings of relative impacts of different fishing gears have been made based on observations and experience. Scallop dredges are generally felt to have a large impact compared to other gears.

The Atlantic sea scallop Placopecten magellanicus industry contributes significantly to the economy of New England. The Northeastern United States sea scallop fishery landed over 60 million pounds of scallop in the 2005-2006 season. This stock now produces a value of over $300 million annually. In 2005, the overall biomass of scallops exceeded BMSY and was therefore no longer overfished.

Scallop dredges used in New England are constructed of heavy steel bar welded into a triangular-shaped frame, with a bag hung from the back made of steel rings (Figures 1 & 2). Current regulations require a 4” ring for scallop size selectivity and a 10” twine mesh on the upper side to reduce finfish by catch. The dredge rides along the sea floor on shoes welded to the dredge at the corners of the triangle where the bag is attached. A pressure plate is mounted along the top rear of the triangular frame to provide some downward hydrodynamic pressure, however, the weight of the frame and chain bag is the predominant downward force assuring bottom contact. A cutting bar (Figure 2) provides structural support to the dredge and plays a much debated role in scallop capture. From underwater video, it is known that the cutting bar can remove the tops of bottom features such as small sand dunes. 

The underside of the chain bag is supported by a chain sweep that hangs in a catenary from either side of the frame. As shown in the photo, it is also common to have tickler chains preceding this sweep chain, presumably in order to lift scallops from the bottom in anticipation of the approaching chain bag. Also shown are rock chains intended to prevent rocks and boulders from entering the bag and damaging the gear and the catch.




The combined weight and amount of hardware in contact with the seabed explains why this type of gear is singled out as uniquely damaging to ocean habitat. Yet, the economic significance of the east coast sea scallop fishery and the traditional use of this gear make the adoption of alternate gear challenging. In spite of this challenge, a clear mandate exists for developing a habitat-friendly and economically viable method of catching scallops.


Vocabulary:  Sea Scallop, dredge, ecosystem, constraint, habitat


·        Prepare a packet of materials for each student team. Snack size zip lock bags can be used to separate small items (nuts, paper clips, etc.) and all materials can be placed in a large (gallon sized) zip lock bag.

·        Plastic tablecloths can be used to protect tables and make cleanup easier.

·        Prepare model ocean environment by placing sand at the bottom of the tank, then model organisms and plants. Fill the tank with water. The tank should be placed so that several groups can gather around the tank at once to make observations


·        Students should work in teams of two or three. (Do not give students design supplies until they are ready to begin the actual building. Once they receive their supplies, most will want to start building right away).

·        Review handout (especially constraints) and assessment rubric with an opportunity for students to ask clarifying questions.

·        Have students make written observations of the model ocean environment and share out to the class.

·        Show students two videos (sea scallop tow, dredging simulation). The schematics of a dredge should not be provided to the students prior to their own design attempts. The purpose of the design challenge is for students to use their own ideas to develop a solution. You may want to share the design schematics with students once they have completed two cycles of design and testing.

·        Students brainstorm ideas with their team. All brainstorming ideas should be written on chart paper. Each team should have several possible solutions to choose from.

·        Using graph paper, students should create a labeled drawing of their proposed solution on chart paper with dimensions.

·        Students build their prototype according to their design.

·        Prototype is tested in the model ocean environment.

·        After the first test, students should be given time to troubleshoot and modify their design.

·        Once they have modified their design, they should re-test and if time allows, make further modifications.

·        Once their design is finalized, students should work together to answer the analysis questions and write their presentations.

·        Each team presents their solution/rationale and answers to questions to the class.

·        Class discussion with feedback and questions from other students.


Student designs must meet the following criteria/constraints:

1.      Students can only use must use only the materials provided (it is not required that they use everything)

2.      Dredge must fall to the ocean floor on its own.

3.      Dredge must remain (flat) on the ocean floor for the duration of the tow

4.      Dredge must capture scallops


Additional Notes

·        Depending on student level, you may choose to assign roles within the group.

·        This activity can be scaled up or down to meet the needs of younger students or more advanced students. The level of challenge will change depending on the constraints given.

·        If space, time and resources permit, each team can be given a small (5 gallon fish tank) model ocean system to use as they work on their design.



Each team will be assessed on how well their design meets the provided constraints. Additionally, each group will prepare an oral and written presentation describing the rationale for their final design and their answers to the analysis questions. See attached rubric.


Science/Engineering Learning Standards:   

New York State Living Environment Core Curriculum


Standard 1

Key Idea 1: The central purpose of scientific inquiry is to develop explanations of natural phenomena in a continuing and creative process.

Performance indicator: 1.1, 1.2

Key Idea 2: Beyond the use of reasoning and consensus, scientific inquiry involves the testing of proposed explanations involving the use of conventional techniques and procedures and usually requiring considerable ingenuity.


Key Idea 3: The observations made while testing proposed explanations, when analyzed using conventional and invented methods, provide new insights into natural phenomena.

Performance indicator: 3.1, 3.4


Standard 4

Key Idea 6: Plants and animals depend on each other and their physical environment.

Performance indicator: 6.1f, 6.1g, 6.3a, 6.3c


Key Idea 7: Human decisions and activities have had a profound impact on the physical and living environment.

Performance indicator: 7.1c, 7.2a, 7.2b


New York State Technology Learning Standards


Standard 5 - Technology

Engineering Design

1. Engineering design is an iterative process involving modeling and optimization used to develop technological solutions to problems within given contraints.


Impacts of Technology

6. Technology can have positive and negative impacts on individuals, society, and the environment and humans have the capability and responsibility to constrain or promote technological development.



1.    National Oceanic and Atmospheric Administration Fishwatch – U.S. Sea Food Facts. “Atlantic Sea Scallops.” Web. Jul 29 2011 <>


2.    Ocean Literacy, The Essential Principles of Ocean Sciences K-12. National Geographic Society. <>


3.    “What is a scallop dredge design.” Web. Jul 29 2011 <>


4.    Garmire, Elsa. "The Engineering Design Method." The Technology Teacher (Dec/Jan 2003): 22-28. Print.


5.    Burghardt, David M and Hacker, Michael. “Informed Design: A Contemporary Approach to Design Pedagogy as the Core Process in Technology.” The Technology Teacher (Sept 2004): 6-8. Print.


6.    Sadler, Philip M, Harold P. Coyle and Marc Schwartz. “Engineering Competitions in the Middle School Classroom: Key Elements in Developing Effective Design Challenges.” The Journal of The Learning Sciences 9:3 (2000): 299-327. Print.


7.    Smithsonian Cooper Hewitt , National Design Museum.  “Educator Resource Center.” Web. 31 Jul 2011 <>


8.    The Tech Museum.  “Design Challenge Curriculum.” Web. 31 Jul 2011 <>


9.    Zubrowski, Bernard. “Integrating Science into Design Technology Projects: Using a Standard Model in the Design Process.” Journal of Technology Education 13.2 (Spring 2002): 48-67. Print.