Impact of reducing investment disincentives on the sustainability of the Moreton Bay prawn trawl fishery

•On average Moreton Bay prawn trawl fishery is economically unsustainable.•Economic performance could be improved with investment in fewer, larger, vessels.•Concerns exist that this would result in increased effort and reduced sustainability.•Increasing vessel size results in less than proportional increases in catch.•The existing hull unit capacity cap appears sufficient to maintain sustainability.