Question

The square mesh cod end is suggested in trawl net fishing gear for

• A. Closing the mouth of trawl net
• B. The escape of juvenile fish
• C. The escape of turtles
• D. Opening the mouth of trawl net

Hint:

Bycatch Reduction Devices (BRDs):
Square Mesh Cod-end $\rightarrow$ Escape of JUVENILE UNDERSIZED FISHES.
TED (Turtle Excluder Device) $\rightarrow$ Escape of SEA TURTLES.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Bycatch reduction technology and trawl selectivity: square mesh cod-ends remain wide open under towing tension, allowing juvenile and undersized non-target fishes to escape unharmed to prevent growth overfishing.
Key Formula or Approach:
\[ \text{Towing Tension: Diamond Mesh (Closes Shut } \implies \text{Trap Juveniles)} \quad \longleftrightarrow \quad \mathbf{Square \text{ } Mesh \text{ (Stays Open } \implies \text{Juveniles Escape)}} \]

Step 2: Detailed Explanation:
In fishing gear selectivity, bycatch reduction devices (BRDs), and sustainable fisheries management:
1. Diamond Mesh Cod-ends (Traditional): When a trawl net is towed under heavy hydrodynamic drag, diamond-shaped meshes stretch longitudinally and narrow sideways, closing the mesh lumens completely shut and suffocating/trapping undersized young fishes.
2. Square Mesh Cod-ends (B): The netting bars are oriented horizontally and vertically at $90^\circ$. Under towing tension, square meshes do not collapse and maintain their full open lumen dimensions, permitting the escape of juvenile and sub-adult fishes unharmed during trawling, thus mitigating growth overfishing.
3. (Turtles escape via Turtle Excluder Devices [TEDs]).

Step 3: Final Answer:
Therefore, square mesh cod-end is suggested for The escape of juvenile fish, corresponding to option (B).