Spanish bottom trawl spring survey “Fletán Ártico 2015” in the Slope of Svalbard (ICES Division IIb2)

Abstract

The "Fletán Ártico 2015" spring survey is a continuation of the Spanish bottom trawl survey series started in 1997 on the slope of Svalbard (ICES IIb2) using commercial vessels. The present survey was carried out from the 19th of June to the 10th of July, 2015 on board a Spanish freezer trawler using a bottom trawl gear. There were 81 valid hauls in which Greenland halibut was clearly the predominant species (Catch per unit effort [CPUE] = 2,758.1 kg/hr; abundance index =155,333 (‘000) individuals; and biomass index = 150,385 tons). In the frame of the spring surveys, the present survey shows a positive trend in these indices, but such values are lower than the ones obtained from the autumn surveys. The latitudinal and bathymetric distributions of the species were similar to those observed in previous years. Population structure was also quite similar to those described previously, with a predominance of males. Modal length was 46 cm for males and 48 cm for females. Mature Greenland halibut individuals were dominant in the catches. Cod (1,120.6 kg), redfish (734.7 kg) and roughhead grenadier (460.8 kg), were the three main accompanying species in terms of weight. When compared to the Greenland halibut, the accompanying species show very low CPUE values and very low abundance and biomass indices. By-catches of Vulnerable Marine Ecosystems (VMEs) indicator species were generally absent or low. Only in two hauls the sea pen by-catches exceeded the NAFO threshold for “significant research vessel trawl sea pen catches”.