Survey-based assessment of recapture data for Atlantic sturgeon (Acipenser oxyrinchus) in Lithuanian fisheries

Against the background of ongoing European activities since the mid-1990s to restore stocks of the extinct Atlantic sturgeon in the Baltic Sea region, from 2011–2018, a total of 6366 sturgeon have been tagged in Lithuania. Despite an information campaign, there has been a drastic decline of reported recaptures within this national, non-reward tagging study. Similar trends have been observed across the whole Atlantic sturgeon distribution area in the Baltic Sea. As commercial fisheries account for most recaptured tagged sturgeon, a survey of Lithuanian fisheries and analysis of fish landings during the 2014–2018 period was performed to evaluate conventional tagging study results. The survey data revealed that reporting rates of tagged sturgeon in Lithuanian territorial waters were 13.3% of the true numbers recaptured in the Curonian Lagoon and 19.3% in coastal Baltic waters. The results showed a marked difference between fishing gear types as the sturgeon bycatch in gill nets was up to eight times higher than in fyke nets. This study emphasized the vulnerability of stocked sturgeon to commercial fishing. The increasing use of fyke nets in conjunction with its lower bycatch of sturgeons could be a strong argument to limit gill net usage in order to reduce fishery-related mortality of sturgeon to safe limits.