Towed underwater television towards the quantification of Norway lobster, squat lobsters and sea pens in the Adriatic Sea

No abstracts are to be cited without prior reference to the author.

Norway lobster (Nephrops norvegicus) is of great commercial importance throughout the Northeast Atlantic and Mediterranean, where it lives in burrows within muddy sediments. In several European countries it is assessed using towed underwater TV techniques. This method is particularly suited to Nephrops because the application of normal fishery‐dependent stockassessment methods is not applicable to this species for a number of reasons. The TV methodology relies on the visual assessment of a known surface area of seabed. The number of Nephrops burrows, whose features are distinct, can be counted and their inhabitants quantified. It follows that, in theory, the same can be done for other organisms or key ecological features which appear on the footage. In this study we report the results of two underwater TV surveys (2009 and 2010) carried out jointly by Italy and Croatia in the Pomo pit, an area of the Adriatic Sea important for its Nephrops fishery and its hake nursery grounds. The footage we obtained allowed us to quantify the density and biomass of Nephrops in the area and gain estimates of the abundances of: (i) the squat lobster (Munida rutllanti) a newcomer to the area, recently reported to have substituted the established Munida intermedia and (ii) the sea pen (Funiculina quadrangularis), whose assessment by means of underwater TV has recently been the object of OSPAR attention. The concurrent quantification of trawling activity from the footage has allowed us to place our results in the context of an ecosystem approach to fisheries management.