Semiquantitative invertebrate benthic data from the Ecosystem Survey collected in 2023 with bottom Campelen trawl.

This benthos data set from the Barents Sea 2023 covers 175 trawl stations and taxonomic identified by 2 shifts (one person) on each of the three involved research vessels (R/V) and made up nine different taxonomists/technicians in 2023. This dataset therefore represents a non-standardized dataset between stations because trawl distance varies between stations, and the skills and qualities vary among the taxonomists/technicians involved.

In the Barents Sea, three R/Vs: G.O. Sars (GS), Johan Hjort (JH) and Kronprin Haakon (KH) used a Campelen 1800 bottom trawl to harvest fish and invertebrate benthos from the seabed. In addition, the trawl also harvested organisms entering the trawl when it is lowered or heaved. R/V “GS” operated in the period 20 August – 14 September 2023, R/V “JH” operated 25 August – 29 September 2024 while “KH” operated in the period 18-30 September 2023.

The Campelen bottom trawl was standardized across the three R/Vs by a rigging of a rock-hopper ground gear and by being towed on double warps. The mesh size was 80 mm (stretched) in the front and 16–22 mm in the cod end. The horizontal opening was 11.7 m, and the vertical opening 4 –5 m. The trawl configuration and bottom contact was monitored remotely by SCANMAR trawl sensors.

The standard procedure for all three research vessels is to tow after the trawl had contacted the bottom with towing speed of 3 knots (this varied from 2.8 - 3.6 knots), equivalent to a towing distance of approximately 0.75 nautical miles (this varied from 0,4-2.2 nautical miles).

The trawl catch was sorted into fish and invertebrate benthos onboard the three R/Vs. In this dataset we present the invertebrate benthos (hereafter called benthos) not the fish catch, and all data registrations represent a single trawl, hence not standardized across trawls or research vessels.

Each benthos taxon is identified to closest possible taxa from the best skills of the taxonomist/technician. The use of standardized taxonomic literature onboard is introduced with annual three-day obligatory coursing for the involved taxonomists/technicians.
After identification the taxa are counted and weighed (i.e., biomass is wet mass) onboard the ship. The count of individuals per solitary species/taxa in the trawl (Number of ind._Total_trawl) and the wet-weight of the individuals per species/taxa in the trawl (Biomass (g wetweight)_Total_trawl) were recorded (colonial species were only wet-weight). We consider the abundance and wet weight as “semiquantitative” because the trawl catch is constantly sieved through the mesh while tawed on the seabed, hauled through the water, entering the ship and finally the ship laboratory.