Differences in fisher demographics and fishing behaviour from concurrent phone-recall and smartphone app surveys of recreational angling in south-western Australia

Traditional methods for collecting robust samples of recreational effort and catch data from offsite mail or telephone surveys are becoming increasingly difficult to obtain. Smartphone applications (apps) that allow recreational fishers to report their effort and catch are a potentially viable data collection tool, but may be biased. We evaluated demographics, effort, and catch of freshwater anglers in south-west Western Australia by comparing independent data from concurrent phone-recall and app-diary surveys for a 12-month period in 2017-2018. Survey modes differed, with higher proportions of app respondents angling in freshwater and being avid anglers. For both survey modes, unweighted mean effort (days fished) was higher in dams than rivers, but was higher from the phone-recall survey for dams and rivers. The unweighted distribution of kept and released catches (number of fish per angler) of rainbow trout (Oncorhynchus mykiss) and redfin (Perca fluviatilis) were similar between survey modes, with higher retention of redfin and higher release of rainbow trout. Kept and released rates of freshwater cobbler (Tandanus bostocki) and brown trout (Salmo trutta) were less common in both survey modes. Lower response rates and higher survey participation by avid anglers (>= 20 days per year) from the app-diary survey may bias survey data. Such bias needs to be addressed when using digital data collection methods, along with improving recruitment and retention of app participants.