The Socio-ecological System of Urban Fisheries in Estuaries

Abstract

Fisheries and urban marine ecology meet within the world’s densely populated estuaries and coasts, where the imperative of dredging, construction and catchment modification occurs alongside the socio-economic characteristics of urban communities. Estuarine fisheries in urban areas have often shifted away from commercial harvest towards recreational fishing, fuelled by a diverse range of motivational factors. These systems are thus often dominated by recreational and subsistence fisheries, with the fisheries system variously impacted by eutrophication, contamination and pollution, altered trophic structure, habitat loss and hard structure. Urban marine ecosystems may be distinguished by the absence of spawning by exploited finfish, coupled with the gradual loss of environmental signals for recruitment, reduced larval supply and loss of nursery habitats for juveniles, but alongside an abundance of hard structure habitats for adults. The shift from commercial fishing to preferential harvest of more predatory “sportfish” means that the historical trophic structure has shifted towards lower trophic levels (e.g. prawns, detritivores, planktivores). We outline urban estuarine fisheries ecology as a developing paradigm defined by the unique ecological attributes of urbanised estuaries, the socio-economic objectives of fishers therein, and bottlenecks to productivity of the species they exploit. We identify goals for future research and management and illustrate these concepts through discussion of stock enhancement with a large estuarine predatory fish.