2023_programme: Understanding the impact of ping interval on acoustically based abundances

• Session: 09. New frontiers in fisheries acoustics: applications- analysis- decision and management tools
  Organiser(s): Victor Espinosa
• Lecture: Understanding the impact of ping interval on acoustically based abundances
  Paper ID: 2068
  Author(s): Boyra Guillermo, Paradiñas Josu, Rico Iñaki, Martinez Udane Nogueira Enrique
  Presenter: Boyra Guillermo
  Abstract: The ping interval is the main parameter controlling along-transect sampling resolution in acoustic surveys. An increase in the detection range or the synchronization of sensors to avoid crosstalk might increase ping interval, reducing sampling resolution. Here we study whether pinging resolution affects the mean acoustic backscattering energy, causing uncertainty and/or bias in abundance estimations. To this end, we echo-integrated a real acoustic survey, followed by the application of a systematic resampling scheme to simulate an increase in ping interval. In each transect, the mean NASC calculated for each simulated ping interval was compared to the original mean NASC values. Transects were characterized according to their heterogeneity and spatial autocorrelation to study their effects on the relationship between abundance error and sampling resolution. The uncertainty increased with the ping interval owing to the highly skewed distribution of fisheries acoustics data. Higher heterogeneity and the lack of spatial autocorrelation were observed to accelerate the loss of precision for increased ping intervals. Although the mean bias across repetitions was zero, the asymmetry of the bias distributions increased with ping interval, leading to a likely underestimation at intervals higher than ~2.5 s. An interactive figure summarizing the obtained results can be found in https://aztigps.shinyapps.io/PingRateStudio/.
• Corresponding author: Dr Guillermo Boyra
  Affiliation: AZTI
  Country: Spain
  e-mail: