Dr Darryn Sward1, Dr Jacquomo Monk1, Dr Neville Barrett1
1University Of Tasmania – Institute Of Marine And Antarctic Studies, Taroona, Australia
The spatially explicit nature of visual transects from remotely operated vehicles (ROVs) makes them a robust tool for visually surveying demersal fish across a range of habitats and depths necessary for comprehensive monitoring. Here we explore the influence of local and regional scales for seabed terrain on demersal fish distributions using abundance and biomass estimates for three key fisheries-targeted species (Nemadactylus macropterus, Cheilodactylus spectabilis, and Notolabrus tetricus). We paired estimates with multibeam echosounder-derived seabed terrain attributes (e.g. aspect, slope, rugosity, hardness) generated across various analysis window scales from 3 m x 3 m to 21 m x 21 m off the coast of the Tasman Peninsula, Tasmania. Generalised additive models were then used to predict regional abundance and biomass estimates for these species and to create species distribution maps across the Tasman Peninsula. Accuracy (i.e. explained deviance, Akaike’s Information Criterion, and root mean square error of training and test datasets) and precision (i.e. coefficient of variation) were used to evaluate the performance of models based on terrain attributes calculated at varying analysis windows. Seabed terrain attributes generated at larger scales (i.e. 21 m x 21 m), particularly for depth, improved the accuracy and precision of most models for N. macropterus and N. tetricus relative to smaller-scale models, but showed inconsistent results for C. spectabilis. This study demonstrated the value of developing an effective methodology for assessing species-habitat dynamics and spatial distributions at ecologically relevant scales that may better inform monitoring strategies.
Presentation Slides – Darryn Sward
Biography:
Dr. Darryn Sward recently graduated with a PhD in Marine Ecology from the University of Tasmania. Her research developed remotely operated vehicles as a tool for visually surveying fish assemblages.
