Collapse of a historic oyster fishery: diagnosing causes and identifying paths toward increased resilience

Abstract

ABSTRACT. Diagnosing causal factors of change at the ecosystem level is challenging because multiple drivers often interact at various spatial and temporal scales. We employ an integrated natural and social science approach to assess potential mechanisms leading to the collapse of an estuarine social-ecological system, and recommend future paths to increased system resilience. Our case study is the collapse of the eastern oyster (Crassostrea virginica) fishery in Apalachicola Bay, Florida, USA, and the associated impacts on local resource dependent communities. The oyster fishery collapse is the most recent in a series of environmental stressors to this region, which have included hurricanes and tropical storms, drought, and the Deepwater Horizon oil spill. We found it likely that the oyster collapse was not related to contamination from the recent oil spill, but rather to factors affecting oyster recruitment and survival, which may have been mediated by both human, e.g., fishing-related habitat alteration, and environmental, e.g., increased natural mortality from predators and disease, factors. The relative impact of each of these factors is likely to increase in the future because of changing climate and increased demand for fishery, water, and petroleum resources. Successful restoration and persistence of a viable oyster fishery will depend on: (1) implementation of some minimal best management practices, e.g., extensive habitat restoration via shell addition, and some spatial closures to harvest, (2) improving environmental knowledge and promoting episodic learning through enhanced monitoring and experimental management, and (3) continued community engagement necessary to produce adaptable governance suitable to responding to future unexpected challenges.

Impacts of anthropogenic and natural “extreme events” on global fisheries

“…In some instances, effects observed in fisheries are due to a succession of extreme events rather than one particular extreme event. The collapse of the oyster fishery in Apalachicola Bay, Florida (USA) was the result of a succession of disasters in the region including hurricanes, droughts and oil spills (Camp et al., ). One particular disaster was not the cause of the collapse, rather the accumulation of environmental and man‐made stressors, thereby pointing to an accumulative effect.…”

Potential impacts of the 2010 Deepwater Horizon oil spill on subtidal oysters in the Gulf of Mexico

“…In contrast to these oil-induced closures, the commercial fisheries in Florida and Texas remained open in 2010. Adult oyster abundances may have de clined in Florida in 2010 after the spill in part as a result of increased fishing in this region to compensate for reduced harvesting in the closed regions and in anticipation of a looming anthropogenic perturbation even though no evidence of oiling has been found in Apalachicola Bay (Havens et al 2013, Camp et al 2015. Collectively, our results suggest that the magnitude of impact from the oiling and response activities might be underestimated since fishing decreased in the most heavily impacted areas relative to previous years and after the spill in less impacted areas (Galveston Bay, Texas, and Apalachi cola Bay, Florida).…”

“…Because higher salinities within estuaries increase oyster diseases, parasites, and predators, intermediate salinities are thought to promote higher oyster survival and potentially greater fishery productivity (Wilber 1992, Seavey et al 2011, Garland & Kimbro 2015; but see Turner 2006Turner , 2009. The Apalachicola Bay oyster fishery collapsed in 2012 likely as a consequence of consistent low river flow leading to increased sal inity, increased oyster parasites and predators, elevated oyster mortality, and eventual recruitment failure and population collapse (Oczkow ski et al 2011, Petes et al 2012, Havens et al 2013, Camp et al 2015. Even after accounting for this and other confounding factors that differed among regions, we found elevated levels of oyster mortality after the DWH oil spill predominately in the regions that were most heavily impacted by it.…”

Freshwater Detention by Oyster Reefs: Quantifying a Keystone Ecosystem Service

“…Oyster reefs also face a variety of anthropogenic threats, making them one of the most endangered marine habitats [4]. The most significant human-induced pressures on reefs include overfishing [5], coastal development [6], changes in hydrology and water chemistry driven by local/regional water management [7], global climate change [8], and interactions among multiple stressors [9]. Globally, estimates of oyster reef decline exceed 85% [4, 10].…”