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Land-based effects on coastal fisheries may occur through a diversity of mechanisms. Changing inputs from the land have included large volumes of suspended sediments and nutrients into the coastal zone, following large-scale clearances of New Zealand’s forests, and the expansion of land-based industries such as pastoral livestock farming, dairying, and exotic plantation forestry. More localised effects from urbanisation have included elevations of heavy metal concentrations and pollution from sewage. Impacts from such activities have continued into the present day. Commercial coastal fisheries have been established over the same time period, with initial periods of heavy utilisation leading to overfishing of many stocks, and subsequent catch reductions to more sustainable levels. Most fisheries are now managed under the Quota Management System which generally applies Maximum Sustainable Yield (MSY) targets, under which stocks are fished down to a level where productivity is thought to be highest. This inevitably leads to large reductions in overall (meta-) population size, and fishing down of the larger and older size/age classes. One assumption inherent in most stock assessment models used to provide advice on changes to catch limits (and of the generally stable catch limits for stocks for which there is no stock assessment model) is that fished populations will move back towards their original size following any reduction in fishing pressure. It is also assumed that environmental influences on the stock and the carrying capacity of the system remain constant over time or fluctuate without much trend. However, substantial changes in …