I'm preparing an FAO report on methods to estimate the efficiency and duration of gillnet and trammel net ghost fishing and the density of derelict gear, and synthesizes estimates of derelict gear and ghost fishing by these gear types.
This is not my area but I know that some work has been done for Northern Australia. The 2012 annual report from GhostNet Australia has information on what types of nets are arriving there and a reference to modelling work on the subject of ghost nets (not a specific on gillnets in the modelling though).
Wilcox C, Hardesty BD, Sharples R, Griffin DA, Lawson TJ, Gunn R. Ghostnet impacts on globally threatened turtles, a spatial risk analysis for northern Australia. Conservation Letters. 2013;6:247-54.
There is some also FAO work in the area (section 2 in particular)
Macfadyen, G.; Huntington, T.; Cappell, R. Abandoned, lost or otherwise discarded fishing gear. UNEP Regional Seas Reports and Studies No.185; FAO Fisheries and Aquaculture Technical Paper, No. 523. Rome, UNEP/FAO. 2009. 115p.
This also just came out, Kim et al.The estimation of derelict fishing gear in the coastal waters of South Korea: Trap and gill-net fisheries. Marine Policy.
We have a paper that is due out shortly which looks at the impacts and 'kill rates' of various types of derelict fishing gear. Send me an email if you are interested in chatting about it or want a pre-print. Cheers, Denise