No abstract

The population dynamics of five remnant rock-wallaby populations (Petrogale lateralis) persisting on granite outcrops in the central wheatbelt region of Western Australia were monitored over a six year period. From 1979 to 1982 all populations remained relatively static or declined for unknown reasons, but circumstantial evidence implicated fox predation. A fox control program was implemented in 1982 on two outcrops and was maintained for four years with the result that the two resident rock-wallaby populations increased by 138 and 223%. Two rock-wallaby populations occupying sites not subjected to fox control declined by 14 and 85%, and the third population increased by 29%. It was concluded that the fox has probably been a significant factor in the demise and decline of native mammals in the past, and that surviving populations are still at risk. Control of predation pressure on nature reserves was shown to be feasible from a management perspective.

No abstract

The Rottnest Island Reserve, located off southwestern Australia, is one of the most popular recreational fishing locations in Western Australia. In the reserve, standard Western Australian recreational fishing regulations apply and there are two small "no-take" conservation sanctuary areas. A roving creel survey of shore-based recreational angling in the reserve was conducted from January to December 2003. In total, 1 053 anglers were recorded which included individuals, families, school groups and angling club members. The total annual shore-based angling effort for Rottnest island was calculated to be 23 899 angler outings and the total catch estimated at 53 994 retained fish. Fishing effort was concentrated in the settlement area on the eastern side of the island and the highest levels of catch and effort were recorded in April, May and July. During the survey, 33 fish species were identified in the catch and the small, pelagic species Australian Herring dominated with 7.27 tonnes caught during the study. Shore-based anglers also caught and released a large number of non-target species. The survey has provided spatial and temporal data that can be used as a benchmark and to support decision making by the Rottnest Island Authority with respect to biodiversity conservation and the Department of Fisheries with regard to management of shore-based recreational angling in the Rottnest Island Reserve.

The abundance of eggs and larvae of sardine (pilchard) (Sardinops sagax) off the south coast of Western Australia was investigated using geostatistical and bootstrap resampling techniques. A two-dimensional correlogram showed that the patch of newly spawned pilchard eggs had dimensions of 8 nautical miles (M) in diameter in the offshore direction and 10 M in the alongshore direction. For older stages, the size of the patch tended to increase and the level of cohesion decrease. It was more difficult to determine the size of the patch from directional variograms. The abundance of 1- and 2-day-old eggs in the study area was estimated using ordinary kriging. A bootstrapping analysis suggested that the optimal sampling design for day 1 eggs should use 4 × 10 M grids, an increase in intensity on the 5 × 15 M grids used in previous surveys.