Directional Acoustic Emitters for Trawl Fish Guidance
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Solution Overview
Problem
Conventional trawls experience low fishing efficiency as fish often evade the net by leaving the towing trajectory, leading to prolonged fishing times and increased fuel consumption, despite sonar identification of fish shoals.
Innovation Solution
The trawl is equipped with directional acoustic emitters that emit sound forwardly at an angle to the towing direction, creating virtual barriers to startle fish and direct them into the net, forming a funnel-shaped virtual extension of the trawl.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional trawls are used without acoustic emitters, then the device complexity is low, but the fishing efficiency is low as fish elude the trawl
Solution Approach 1:
The patent replaces the purely mechanical net structure with an acoustic field-based system. Directional acoustic emitters generate sound barriers that startle fish and redirect them into the trawl, substituting mechanical capture with acoustic manipulation of fish behavior. This increases productivity by preventing fish escape while adding controlled acoustic components to the traditional mechanical trawl design.
Solution Approach 2:
The patent introduces sound as an intermediary between the trawl and the fish. The acoustic emitters generate sound waves that act as a mediating force, startle the fish, and redirect their swimming path toward the net. This intermediary acoustic field enables the trawl to capture fish without direct mechanical contact, improving capture efficiency while maintaining relative simplicity in the overall system.
2Productivity
If acoustic emitters are added to the trawl, then fishing efficiency improves by preventing fish escape, but the device complexity increases
Solution Approach 1:
The patent applies acoustic emitters selectively at specific locations on the trawl - namely on the trawl doors and at the leading edges of the bag-shaped net. This localized placement creates directional sound barriers precisely where needed to intercept and redirect fish, improving capture efficiency at critical points without requiring acoustic emitters throughout the entire trawl structure, thus limiting the increase in device complexity.
Solution Approach 2:
The acoustic emission system is segmented into discrete emitters positioned at specific locations (trawl doors and leading edges) rather than a continuous system. This segmentation allows the system to achieve effective fish redirection through strategic placement while keeping the overall complexity manageable by using only essential emission points rather than comprehensive coverage.
3Productivity
If sound is emitted continuously to maintain fish redirection, then fishing efficiency remains high, but energy consumption increases
Solution Approach 1:
The patent employs periodic or intermittent acoustic emission rather than continuous operation. The directional acoustic emitters operate in controlled cycles, emitting sound at intervals sufficient to maintain fish redirection and startle effects while allowing energy consumption to be managed. This periodic action maintains fishing efficiency through repeated acoustic barriers while preventing excessive energy expenditure from continuous operation.
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
This approach significantly increases fishing efficiency by preventing fish from eluding the trawl, reducing the need for extended fishing times and fuel consumption, while the acoustic emitters' specific frequency range and intermittent operation ensure effective startling without interfering with vessel systems.
Implementation Method 1
the trawl comprises directional acoustic emitters adapted to emit sound forwardly at an angle to the towing direction
Implementation Method 2
barriers of sound are provided in front of the trawl. These barriers form virtual extensions of the trawl because the sounds will startle fish approaching the barriers of sound, and make the fish change swimming direction when they approach the barrier
Data Source
Figure 1~2
Figure 3~4
AI summary
A trawl (1) adapted to be towed in a towing direction (D) along a desired towing trajectory behind a towing vessel (4). The trawl (1) comprises directional acoustic emitters (13) adapted to emit sound forwardly at an angle to the towing direction (D). The sound is adapted to startle fish (8) and provide barriers of sound (12) for the fish (8), thus forming a virtual extension of the trawl (1). The trawl (1) is used in a method of fishing.