Degradable Cull Ring Panels for Derelict Crab Traps
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Solution Overview
Problem
Derelict crab traps in estuarine waters cause environmental and economic issues due to their continued ability to capture and kill crabs and fish, despite degradable components failing to render them ineffective after degradation.
Innovation Solution
Incorporating degradable cull ring panels made from polycaprolactone or polyhydroxyalkanoate polymers into crab traps, which break down within 3 to 18 months, allowing trapped organisms to escape, and can be easily integrated into existing traps using wire clips or ties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If degradable panels are used in crab traps, then environmental impact is reduced, but traps continue to capture organisms long after degradation
Solution Approach 1:
The trap is divided into degradable panels and non-degradable frame components. The panels are segmented to allow independent degradation while maintaining trap structure, enabling partial functionality loss as panels degrade over time.
Solution Approach 2:
The trap transitions from a static structure to a dynamic one where panels progressively degrade and change properties over time. The trap's trapping effectiveness dynamically decreases as panels degrade, eventually allowing organism escape.
2Object-affected harmful factors
If cull rings are installed to allow small crabs to escape, then juvenile crab mortality is reduced, but trap selectivity is compromised
Solution Approach 1:
Different regions of the trap have different properties: cull rings provide localized escape openings with specific diameter requirements, while other trap regions maintain their trapping functionality. This local differentiation allows simultaneous achievement of juvenile protection and adult crab capture.
3Duration of action of stationary object
If degradable materials are used for trap components, then derelict trap persistence is reduced, but trap structural integrity deteriorates
Solution Approach 1:
The trap combines degradable materials (panels, twine, netting) with non-degradable materials (metal or plastic frame, buoys). This composite construction allows different components to have different durability characteristics, with degradable parts providing temporary structure and non-degradable parts providing long-term framework.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The degradable cull ring panels effectively reduce the entrapment and mortality of undersized crabs and fish by ensuring derelict traps lose their trapping ability within a specified time frame, addressing the ecological and economic impacts of derelict gear.
Implementation Method 1
degradable cull ring panels made from polycaprolactone or polyhydroxyalkanoate polymers into crab traps, which break down within 3 to 18 months
Data Source
AI summary
Herein we describe crustacean fishing traps having degradable cull ring panels, as well as methods for ensuring that such traps have reduced functionality after becoming derelict. Derelict crab and lobster traps have a negative economic and ecological impact, and thus it is advantageous to use degradable traps that will lose their ability to catch and retain fish over time. Incorporating degradable cull ring panels into such traps provides an effective, economical solution. Suitable degradable cull ring panels are described herein.