males, "sneakers" mimic female colouring and form to gain access to the females being protected by the dominant males, which are extremely territorial. Male genetic material is deposited in sperm receptacles directly. The females, which potentially lay hundreds of eggs, extract one egg at a time and fertilise it by passing it over the sperm receptacle before attaching it to the underside of a rock at depths of . Conservation An unsuccessful application to list this population of giant cuttlefish as a threatened species under Australian law was made during the government's consideration of BHP Billiton's Olympic Dam mine expansion project. The application was made following an observed and unexplained population decline and public concerns about future risks posed by industrial pollution. On February 2, 2011, the Australian government's Threatened Species Scientific Committee ruled that the species was not eligible for listing, as the affected population was not taxonomically distinct from the rest of the species for the purposes of the Act. Further scientific work has determined the cuttlefish of northern Spencer Gulf to be genetically distinct from other giant cuttlefish populations in Australian waters though the results remain unpublished. Commercial fishing Prior to the mid-1990s, the upper Spencer Gulf population was fished for snapper bait, with annual catches of around 4 tonnes (4,000 cuttlefish). During the 1995 and 1996 spawning seasons, commercial fishing of the spawning grounds harvested around 200 tonnes annually. Overexploitation was recognised after 245 tonnes were harvested in 1997, leading to 50% of the grounds being closed to commercial fishing in 1998. Despite half of the grounds being closed, commercial fishers took 109 tonnes in 1998 (about half of the estimated biomass) before dropping to 3.7 tonnes in 1999. The catch data for 2000 to 2005 were initially withheld citing commercial confidentiality. Catch data for the South Australian cuttlefish fishery are reported in annual reports of the Marine Scalefish Fishery, published by SARDI. The pre-2014 data are graphed below. From its establishment in 1987 to the financial year ending June 1992, the fishery caught less than 3 tonnes per annum. Population decline Surveys indicated that the cuttlefish biomass remained stable from 1998 to 2001 as commercial fishing pressure was reduced by regulation. A survey in 2005 revealed a 34% decrease in biomass since 2001 that was attributed to natural variability and illegal fishing during the peak spawning period. The closure was subsequently expanded to the entire