UC Merced

Consumer demand for sustainably sourced seafood has given rise to eco-label initiatives such as the Marine Stewardship Council and consumer advocacy groups such as Monterey Bay Aquarium’s Seafood Watch. The sustainability metrics of these groups include bycatch avoidance (with a particular emphasis on protected species) and stock abundance but have yet to include the climate impact of seafood production activities. The literature related to the sustainability of seafood generally reflects the emphasis of these eco-label initiatives with an abundance of studies related to stock assessment and eco-system effects of bycatch but comparatively few studies dedicated to the life-cycle assessment of seafood production activities. The dearth of seafood life-cycle assessments that have been conducted are narrowly focused on greenhouse gas emissions during fishing activities. Although greenhouse gas emissions of fishing activities is important, these studies have overlooked the climate implications of several policies (current and proposed) that may influence the sustainability of seafood. First, policy aimed at improving air quality by reducing the sulfur levels in marine fuels may impact the sustainability of seafood because fishing vessels are heavily reliant on diesel fuel and are known to be high emitters of short-lived climate forcing pollutants (including black carbon, sulfur oxides, and organic carbon). Furthermore, as seafood is a globally traded commodity that is typically shipped as freight on large container vessels, the importance of fuel quality in seafood life-cycle assessments may not be limited to the fishing phase of the seafood supply chain. Second, the consumer-driven policy of major retailers to only source seafood caught with highly selective fishing gears—in order to avoid the collateral damage of bycatch—may influence the sustainability of seafood because these gear types may require more fuel per fish caught compared with less selective gear types. Third, it has been argued that a proposed policy to ban fishing the high seas would allow the high seas to serve as an ecological bank. However, this proposal could impact the sustainability of seafood because fishermen may use less fuel by fishing in coastal areas. Furthermore, restricting fishing activities to coastal areas would mean that fishermen would be subject to more stringent fuel sulfur laws in regions where emission control laws have been enacted. Despite the potential benefits of these policies—improved air quality, reduced bycatch, and improved stock abundance—the climate impact of these sustainable fishing practices is largely unknown. This dissertation seeks to study the climate impact of these practices so as to broaden the discourse surrounding sustainable fishing practices.

This work is divided in three research efforts. First, this research investigates the role of fishing vessels in the context of global shipping inventories. It develops a global inventory of fuel consumption and emissions of short-lived climate forcing pollutants of fishing vessels. A first-order global and Arctic estimate for the emissions and climate forcing of combined long-lived climate forcing (i.e. well mixed-greenhouse gases) and short-lived climate forcing emissions from fisheries using recently published plume-sampling data from an ensemble of ships is developed. Second, this research evaluates the climate impact of current and proposed policies (fuel quality policy to improve air quality, consumer-driven retailer policy to source seafood from highly selective fishing gears, and the proposed ban of fishing the high seas) in the context of U.S. tuna fisheries. A first-order climate forcing assessment of fishing activities of selected U.S. tuna fleets was conducted and the results were compared to land-based protein sources. Third, this research investigates the role of short-lived climate forcing pollutants upstream of the fishing phase of the seafood supply chain. A life-cycle assessment model was developed that includes fishing, processing, and the transport of two Alaskan pollock seafood products. Short-lived climate forcing pollutants were added to an existing model of battered-and-breaded white-fish fillets. Furthermore, a first-order assessment of a pollock surimi product, crab-flavored sticks (i.e. imitation crab), was compared to climate forcing associated with battered-and-breaded pollock fillets.