Testing the influence of survey method for building species distribution models of marine fishes

Accurate estimates of fish species occurrence are important to any species’ assessments and habitat suitability model. However, surveys of marine fishes are often biased by method. Surveys of marine fishes are often biased by method. Such bias could influence the interpretation of any habitat suitability model. With increasing emphasis on non-destructive sampling, underwater video techniques are commonly used without a thorough understanding of their advantages and disadvantages. This study compared data collected from baited remote underwater stereo-video systems and towed-video systems to provide occurrence data to develop habitat suitability models of nine temperate marine fishes. While numerous studies have compared modelling approaches in terms of model performance (i.e. via AUC or Kappa) the point of this paper was to highlight how very sensiblelooking, well-performing (based on AUC) models can provide different predictions of habitat suitability depending on which dataset is used.

Predicting changes to seascapes under future climate, with the Coorong as a case study

The marine and estuarine ecosystems of South Australia are likely to alter significantly in response to a changing climate, but also in response to managerial decisions we make. The allocation of fishing effort is an example of one such decision. We summarise some projections on a state-wide basis for how different components of these ecosystems may be expected to change. We anticipate that tropical elements will expand in range but cold-temperate communities will contract or disappear from South Australia. As a specific example, we have modelled the ecosystem states of the Coorong and the Murray Mouth. We combined biological and physico-chemical components of an ecosystem into co-occurring units (termed ecosystem states) with well-defined thresholds between them. Predictions were then made using time series of inputs from modelled water flows and other predictors. Using this model, we will discuss the likely implication of a range of climate change and management scenarios, highlighting the potential impact on the commercial fishing opportunities. Specifically we will discuss the potential sensitivity of the fishery to climate changes versus various management options. Understanding these possible future changes should allow the industry to adapt before climate change reduces the sustainability of the industry.