engleski

FISH POPULATION ASSESSMENT IN THE EASTERN ADRIATIC SEA: BAITED, REMOTE, UNDERWATER VIDEO (BRUV) VERSUS TRAMMEL NET SAMPLING

Development of non-destructive, fisheries- independent methods of fish population assessment, behavioural ecology, and habitat choice are a conservation priority within the European Union. In this paper we evaluated (1) the suitability of two alternative methods for fish population assessment: trammel net sampling and non-destructive BRUV (Baited Remote Underwater Video), and (2) the potential to cross-calibrate the methods based on a set of shared species with high catch probabilities within the eastern Adriatic Sea (Croatia). A statistical power analysis concluded that BRUV can be conducted with sufficient sample size to perceive small changes in fish population size with high power, and therefore can be used as a sentinel monitoring method. We found that fish species detected by both methods amounted to almost a third of the number of species in each method’s catch, and that 90% of these species are candidates for cross-calibration. 74% of the species at BRUV and 50% at trammel had occurrence probabilities above 10%, a reasonable threshold allowing stock assessment of these species. The sampled and predicted total species richness, extrapolated from the species accumulation curves, was almost identical across methods. We conclude that cross-calibrating the two methods and eventual replacement of the trammel method with non- destructive BRUV is a feasible goal in the eastern Adriatic Sea. The most needed areas of improvement currently are optimization of night-sampling methods and development of more effective strategies of attracting sedentary species within three-dimensional habitat cover. This work has been supported under the Croatian Science Foundation under the project COREBIO (3107).

Fisheries independent methods, trammel netting, Baited remote Underwater Video, BRUV, cross-calibration

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