Abstract
In 2024, a series of fish kill events were observed at the Coastal Virginia Offshore Wind-Commercial (CVOW-C) project located 44 km off of the coast of Virginia Beach, VA USA during a period of project-related construction activities. Fish kills have not previously been reported in the peer-reviewed literature in relation to offshore wind construction activities worldwide. Observational data collected by protected species observers during the CVOW-C fish kill events indicate that approximately 18,000 fish were killed. The majority of dead fish were identified as Atlantic croaker (Micropogonias undulatus) and a smaller number were identified to be spot (Leiostomus xanthurus). Two separate opportunistic necropsies were conducted by independent institutions on 35 fish killed. The injuries identified by the necropsies included skeletal trauma, muscle damage, internal and external decapitation, deflated swim bladders, and intravascular gas bubbles within the gills. Neither necropsy was able to determine a definitive cause of fish mortality or injury based on the information available. The combination of injuries reported in the necropsies suggest that specimens may have experienced acute trauma prior to or during rapid ascent in water supersaturated with dissolved oxygen. Analysis of passive acoustic monitoring (PAM) data from PAM recorders located in the area found no correlation between changes in the acoustic environment and observations of the fish kills. Although the fish kills are suspected to be associated with construction activities, their specific cause is not known. Other activities that occur during the offshore wind construction process should be evaluated. In particular, the operation of the double big bubble curtain may have played a role and should be examined to determine its potential involvement in the mortality of affected species. The CVOW-C fish kill events were unexpected, and therefore, there were no plans in place for addressing such events at the time they occurred. There is a clear need to establish a standardized protocol that is incorporated into the terms and conditions of BOEM’s approval of a developer’s Construction and Operation Plan (COP) to address the potential for future fish kills associated with construction activities for offshore wind or other marine development projects on the outer continental shelf. The addition of a fish kill Monitoring and Response Plan included in future COP terms and conditions should detail when and how to collect, preserve, analyze, report, store, and share data associated with potential future fish kill events. A standardized established protocol will enable a better understanding of potential causes of these events and help to advance approaches for avoiding, minimizing, and/or mitigating future events.