A comparison of the efficiency of escape gaps and deck grid sorters for the selection of legal-sized rock lobsters Jasus lalandii
Crous, H.B. (1976). A comparison of the efficiency of escape gaps and deck grid sorters for the selection of legal-sized rock lobsters Jasus lalandii. Fisheries Bulletin (South Africa) 8: 5-12
In: Fisheries Bulletin: Contributions to Oceanography and Fisheries Biology = Visserye-bulletin: Bydraes tot oseanografie en visserybiologie. Department of Agriculture and Fisheries. Sea Fisheries Institute: Cape Town. , more
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| Keywords |
Catching methods
Data > Fishery data > Catch/effort
Escapement
Fishing > Catching methods > Trap fishing
Fishing grounds
Gear selectivity > Mesh selectivity
Nets > Fishing gear > Fishing nets > Trap nets
Population characteristics > Population structure > Size distribution
Population functions > Mortality
Jasus lalandii (H. Milne Edwards, 1837) [WoRMS]
Marine/Coastal |
| Abstract |
A comparison between the results obtained by using traps fitted with escape gaps and standard traps used in conjunction with a deck grid sorter showed that the latter combination was more efficient, probably because of the larger area available for sorting. The use of escape-gap traps was not advantageous, because emptying these traps required a more complicated procedure than simply releasing the slip knot on the bag attached to a standard trap. As fishing often takes place under adverse conditions at sea, there is also the likelihood that the grids fitted to escape-gap traps could become distorted, gap sizes could change and the system would therefore become less efficient. An additional advantage of the deck grid sorter would be the costs involved in outfitting a boat. The cost of a deck grid sorter averages out at +- R150 per unit compared to R10 per trap in the case of escape-gap traps. As most of the commercial trap-fishing boats operate with {approx} 60 traps, this makes it an expensive modification compared with the deck grid sorter. Although escape gaps do allow rock lobsters below the legal size to escape, the deck grid sorter proved to be the most efficient and economical escape mechanism available to the commercial rock-lobster fisherman. |
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