While many explanations have been proposed for the 1990s Atlantic Canadian groundfishery collapse-ranging from natural causes to over-fishing and damaging technologies, to failures of fishery management and science-this paper examines the possibility that underlying these, at the roots of the collapse, liae set of entrenched attitudes that have driven fishery decision making. These attitudes, about the natural world, about management and about how the fishery should function, became influential especially where they prevailed at the institutional level, as the accepted wisdom among the dominant players in government and the fishery. Four sets of conservation-related attitudes are considered, dealing with (1) the extent to which management responsibilities are accepted and shared by fishery regulators and fishers, (2) the burden of proof and where it should lie in judging conservation concerns, (3) a view that conservation can wait , to avoid disrupting catches and fishing activity, and (4) a belief that the system works , that fundamental change in fishery management is unnecessary. It is noted that a failure to modify attitudes in the fishery may well lead to a situation in which history once again repeats itself