Fishing Gear, Craft and Techniques
Fishing Gear, Craft and Techniques
This domain tests gear classification, selectivity, craft types, and fishing operations. You must know why a gear is chosen for a species, depth, and seabed.
Core rules
- Passive gear waits for fish: gillnets, entangling nets, traps, and longlines. Active gear chases or encircles fish: trawls, purse seines, and cast nets.
- Gillnets catch fish by the gills or body behind the operculum; mesh size determines selectivity. Small mesh catches juveniles and increases bycatch.
- Trawls are towed; the codend mesh releases undersized fish. Square-mesh codends reduce discard mortality compared with diamond mesh.
- Purse seines encircle pelagic schools with a purse line; they are not bottom trawls.
- Craft: catamarans, plank-built boats, and FRP boats. Safety equipment and registration are examinable.
Worked example
A trawler uses a 30 mm codend and lands mostly 12 cm juvenile croakers. The operator changes to a 40 mm codend. The larger mesh lets small fish escape before they are crushed in the codend, so the catch has fewer juveniles and a higher average price per kg. The trade-off is a temporary loss of bulk catch, offset by better market value and compliance.
Traps
Do not call a gillnet an active gear; do not confuse purse seine with trawl; do not measure mesh as the distance between knot centres when the rule asks for stretched mesh; and do not ignore bycatch and discards.