Listening for marine mammals in and around the Maryland Wind Energy Area Photo courtesy of Helen Bailey Offshore windfarms provide a clean, renewable source of energy, but activities during the construction phase can potentially affect marine mammals. To collect baseline data on when and where marine mammals occur within the proposed Maryland Wind Energy Area (WEA) off Ocean City, MD, scientists deployed underwater listening devices to record the ambient noise levels and marine mammal calls. The large whales (fin, humpback, minke, and North Atlantic right whale) and harbor porpoises were mainly detected from November to April. Dolphins were most common during April to October within and inshore of the WEA whereas they tended to occur more frequently offshore of the WEA from December to May. These results will help inform regulators so that appropriate protection and mitigation measures can be developed. Marine mammals use sound for communication, hunting, and navigating. Information on the occurrence of marine mammals can therefore be obtained non-invasively by listening to their calls, an approach called passive acoustic monitoring. Dr. Helen Bailey’s team, at the University of Maryland Center for Environmental Science, and Dr. Aaron Rice’s team, at Cornell University, moored underwater microphones (called hydrophones) on the seabed to listen for the calls that whales, dolphins and porpoises produce. By recording and analyzing these calls, researchers are able to understand each species’ distribution in space and time, seasonal patterns of their occurrence, and behavior. Data was collected from November 2014 to October 2017. Underwater listening devices were deployed inside and outside the Maryland WEA. Twelve ! devices sensitive to the low-frequency calls ! Sources: Esri, GEBCO, NOAA, National Geographic, of large whales (MARUs) were deployed Ocean City ! ! ! throughout the WEA, inshore and offshore of ! ! ! ! the WEA (red circles). Four devices that can ! ! !! detect dolphin and porpoise clicks (C-PODs) were deployed in a transect line across the Legend Wind Energy Area (WEA) area studied (black circles) and a further four N MARU sites were added inside the WEA in 2017 (gray C-POD 01^5 0 C-POD added in 2017 km circles). Ocean City, Maryland Esri, Garmin, GEBCO, NOAA NGDC, and other contributors Marine mammal seasonal patterns ottlenose dolphins were frequently detected over all sites year-round, except February, but Bot tlen or porpoise os were more prevalent within and inshore Harb e d olp hi of the WEA. Common dolphins n occur offshore of the H um p b WEA and detections were June a ck J w consistent from December y uly h le a a le M le a a to May. arbor porpoise h h w w e k k c Harbor porpoise were present in a A b u M g p il r u consistently from m p s t u A H Bottlenose dolphin December to June Humpback whale Su ng m and detections ri m p e S r S e revealed foraging p M t e a m r mainly occured in c b h Minke whale e r r F the evening to e a t l n l i early morning W H F e r hours. Minke u b e m r b u North Atlantic right whale o p a t r c whales, b y Fin whale O e a l c a k h the smallest of the large w w h in a Ja r F whales, were occasionally l n be e ua Common dolphin m ry ve No detected in January and N o December rt h from March to May. At M lan i tic nk rig umpback whales e ht w wh hale ale during their migration Humpback whale through the mid-Atlantic in December, January and March through May. Occasional detections Co mmon dolphin Occasional detections were recorded in February, July, and August. The critically (10-29% days per month) Frequent or regular detections endangered North Atlantic right whales (NARW) were most prevalent (30% or more days per month) from November to April, with occasional detections until July. NARW primarily moved within a nd offshore of the WEA, including through an area of high ship trafc on the offshore edge of the WEA approaching Delaware Bay. Endangered fin whales were the most frequently detected large whale species with the highest detections offshore of the WEA. Fin whales were detected year round, but less so in June. This study describes the seasonal occurrence of whales, dolphins and porpoises within and around the Maryland Wind Energy Area. This information can be used to inform which species will be most at risk of disturbance by offshore wind energy construction and operation activities, as well as when and how those impacts can be most effectively mitigated. This material is based upon work supported by the Maryland Department of Natural Resources, Maryland Energy Administration’s Offshore Wind Development Fund and the U.S. Department of Interior’s Bureau of Ocean Energy Management, Environmental Studies Program (Contract numbers 14-14-1916 BOEM & 14-17- 2241BOEM). Symbols courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/symbols/). Disclaimer: The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Government, the Maryland Department of Natural Resources, or the Maryland Energy Administration. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Government or the state..