Using predator cues to enhance prey defenses may improve survival of cultivated species and enhance species restoration efforts, but assessment of such benefits across relevant scales and identifying the chemical cues responsible for these morphological changes is needed. Oysters, Crassostrea virginica, develop heavier, stronger shells in response to chemical cues from predators and injured conspecifics. We investigated if oyster morphology could be manipulated with predator cues to improve survival and bolster restoration. Through a series of collaborative experiments with state agencies, NGOs, and industry, we tested the costs and benefits of this approach in the field. Although diploid and triploid seed oysters exposed to predator cues were initially smaller after one month of exposure to blue crab Callinectes sapidus predators (Figure 1), after one year, they had similar sizes and tissue masses to controls (Figure 2). We restored an oyster reef using spat-on-shell raised with blue crabs or raised in controls without predators and found that oysters raised with blue crabs had 68% higher survivorship than controls after one year (Figure 3). Concurrently, we ran bioassays to identify the chemical cues predators release that stimulate oysters to grow stronger shells. We exposed oysters to eight different concentrations of urine extracted from blue crabs as well as candidate molecules for inducing defenses. Oyster shell strength increased by 20 – 100% when exposed to predator cues and followed a standard dose response curve with crab urine concentration causing shell strength to peak at ~0.19 mL urine/L seawater. Five molecules in blue crab urine that trigger shell hardening in oysters have been identified. Thus, remote setting can benefit from manipulating oyster shells with predator cues to improve survival for oyster restoration and on-bottom aquaculture. Our findings demonstrate the utility of using predator cues to enhance the survival of target species and highlight an opportunity to employ nontoxic methods to control pest-based mortality.