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BENTHIS Case Study: Modified beam trawl reduces fuel costs in the Samsun Shelf Area, Black Sea, Turkey
In the Black Sea, BENTHIS focusses on the beam trawl fishery for rapa whelks (Rapana venosa) in the littoral zone of the southern Black Sea. Researchers test the performance of the traditional fishing gear against innovative fishing gear, in order to reduce fuel costs.
The traditional fishing gear (algarna trawl) consists of a beam with two shoes and a steel rope between the shoes. The major modifications in the innovative trawl were the use of sledges instead of traditional shoes and the removal of the steel rope between the shoes.
By doing this, the researchers observed a 4-5 % reduction in fuel consumption by the modified gear. Camera footage showed that the modified gear fished just as well as the traditional one. The results also indicated that the steel rope between the shoes does not penetrate into the sea bottom contrary to the researchers’ previous assumptions.
Both trawl types were also tested in terms of resistance of the fishing gear against the sea bottom by using a digital force gauge meter. The trials were repeated in different types of substrates such as sand, sandy mud and muddy sand. All operations were supported by underwater video camera shots (GoPro Hero 4) to observe the functionality of modified fishing gear.
Juvenile fish were mostly able to escape from the gear except some small flatfish species such as scaldback (Arnoglossus kessleri) and some pipefish species (Syngnathus sp). Besides the target species Rapana venosa, the main bycatch species were common bivalves Anadara cornea and striped venus (Chamelea gallina) and crustaceans such as the arch-fronted swimming crab (Liocarcinus navigator) blue-leg swimming-crab (L. depurator) in the Samsun Shelf Area.
