Estimating the Potential Fishery Benefits from Targeted Habitat Repair: a Case Study of School Prawn (Metapenaeus macleayi) in the Lower Clarence River Estuary

Abstract

Development around estuaries leads to degradation of tidal wetlands and alteration of tidal flows, which impacts on fishery productivity. Contemporary management seeks to lessen land-use impacts on aquatic environments and restore ecosystem services, and knowledge of potential benefits will inform investment and galvanize community action. We present a framework to estimate the potential benefits that may be derived from wetland repair, demonstrated through a case study for School Prawn (Metapenaeus macleayi) in Lake Wooloweyah, Clarence River estuary. Under a scenario of good School Prawn recruitment, habitat repair could yield a benefit of ~94 kg ha−1 of subtidal creek habitat, equating to a gross value of around AUD876 ha−1 and total output of around AUD5,175 ha−1 annually. Upscaling these calculations to reflect a scenario restoring 27.6 ha of subtidal channels at the mouth of Lake Wooloweyah would contribute an expected annual yield of 2569 kg in School Prawn harvest. These estimates are conservative, not accounting for the economic outcomes derived from other species directly utilising the additional habitat, or the outwelling of additional saltmarsh-derived productivity. Simple models such as this are useful for assessing the potential benefits of habitat repair, and supporting investment of resources into on-ground works.