Assessing conservation conflict: Does intertidal oyster aquaculture inhibit foraging behavior of migratory shorebirds?

Abstract

Abstract Conservation is increasingly in conflict with human activities due to global human population growth, particularly in areas that support threatened species. Conflicts often impede effective implementation of needed conservation measures and also have implications for social inequality, resource use and economic development. Bivalve molluscan shellfish aquaculture is commonly considered one of the least impactful forms of protein production worldwide but, in some locations, may interfere with essential activities of threatened species such as the stopover ecology of migrating shorebirds. Here we assess the impact of oyster aquaculture as practiced in Delaware Bay (New Jersey, USA) on the presence and foraging behavior of migratory shorebird species of conservation concern. We conducted counts and behavioral observations of shorebirds across a 4.8‐km stretch of the Delaware Bay and tested the effect of regulated aquaculture structures and activities on shorebird presence relative to various environmental factors. We also evaluated differences in mean peck rates for each species within and away from aquaculture areas, and we examined multiple factors influencing foraging rates for each species. For all species, we found that oyster tending reduced the probability of shorebird presence by 1–7%, whereas the untended aquaculture structures had no detectable impact. Foraging rates were mostly influenced by environmental conditions, particularly the presence of competitors (gulls or other shorebirds), and the foraging substrate. None of the focal species substantially altered their time budget or foraging rates in the presence of tended or untended oyster aquaculture. This evidence suggests that intertidal oyster aquaculture and migrating shorebirds can co‐utilize the resource rich intertidal areas on which they occur.

Keywords

• aquaculture
• evidence‐based conservation
• red knot
• ruddy turnstone
• semipalmated sandpiper
• stopover ecology