| Summary: | Executive Summary This study was focused around Becher Point, a cuspate foreland located at the southern tip of Warnbro Sound along the lower west coast of Australia in the Shoalwater Islands Marine Park. Becher Point is a well-known ‘nursery’ site for juvenile Whitebait, which are an important food source for Little Penguins from nearby Penguin Island. This study, which forms a companion project to that by Cannell (2013) to determine current penguin population estimates and diets, had two overarching aims. The first aim centered on understanding the extent and key ‘drivers’ of any historical, interannual changes in both the (1) abundance of Whitebait and composition of the broader fish community in the nearshore waters at Becher Point since the mid-1990s (Objective 1), and (2) survival and breeding performance of Little Penguins since the mid to late-1980s (Objective 2). The data sets used to address this aim included (i) fishery-independent fish data collected by the WA Department of Fisheries (DoF) using a 60.6 m beach seine net in most years since 1996 for Whitebait and all years since 2007 for the full fish assemblage; (ii) penguin survival estimates and breeding performance measurements collected by Murdoch University researchers in various years since 1986; (iii) a suite of environmental variables that may influence fish abundance and/or penguin biology, collated from various sources since 1988, and; (iv) catch-per-unit-effort data for Whitebait and other penguin prey species (Blue Sprat, Australian Sardine, Australian Anchovy and Southern Garfish) obtained from commercial fish catches in the Warnbro Sound and surrounding regions. The second aim was to determine whether a boat ramp constructed at Becher Point in 2010 has impacted the distribution and abundance of Whitebait, or the characteristics of the fish community, in this region (Objective 3), and design a cost-effective Whitebait monitoring regime for the future (Objective 4). The fish faunal data sets used here included those collected by Murdoch University researchers using a 21.5 m seine at (i) five nearshore sites around Becher Point (including at the boat ramp) from August-January of 2011-12, 2012-13 and 2013-14 (hereafter 2011, 2012 and 2013), and; (ii) two of the above sites in 1996/7 (hereafter 1997), 2000 and 2001, which was used to provide some comparable historical basis for understanding the ‘pre-boat ramp’ fish fauna. The inability, however, to collect fish data at the full suite of sites using the same net type in the year(s) immediately preceding boat ramp construction is recognised as a weakness of this part of the study.
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