STUDY TITLE: Occurrence of Commercially Important and Endangered Fishes in Delaware 

Wind Energy Areas Using Acoustic Telemetry

REPORT TITLE: Occurrence of Commercially Important and Endangered Fishes in Delaware 

Wind Energy Areas Using Acoustic Telemetry

OCS STUDY NUMBER: BOEM 2020-020

NUMBER OF PAGES: 80

CONTRACT NUMBER(S): M16AC00009

SPONSORING OCS REGION: Office of Renewable Energy Programs

APPLICABLE PLANNING AREA(S): Mid-Atlantic 

FISCAL YEAR(S) OF PROJECT FUNDING: FY 2016; FY 2017; FY 2018

COSTS BY FISCAL YEAR: FY 2016: $252,807; FY 2017: 4148,916; FY 2018: $35,407

CUMULATIVE PROJECT COST: $437,130

COMPLETION DATE OF REPORT: January 2020

PROJECT MANAGER(S): Matthew J. Oliver

AFFILIATION (OF PROJECT MANAGER): College of Earth, Ocean, and Environment, 

University of Delaware

ADDRESS: 700 Pilottown Rd. Lewes, DE 19958

PRINCIPAL INVESTIGATOR(S)*: Danielle E. Haulsee, Matthew J. Oliver, Dewayne. A. Fox

KEY WORDS: Atlantic Sturgeon, Winter Skate, offshore wind energy development, species 

occurrence and distribution, acoustic telemetry

BRIEF ABSTRACT: There is increasing interest in the development of offshore wind energy 

projects to supply electricity to growing coastal populations. How these projects may affect 

commercially or ecologically important fish species is unknown. This study was conducted to 

document the occurrence and distribution of a commercial fish species, winter skate (Leucoraja 

ocellata), and an endangered species, Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus), over 

a two-year period in the Delaware Wind Energy Lease Area using acoustic telemetry. A total of 

124,710 acoustic detections from 26 species were recorded at stations around the perimeter of 

the Delaware Wind Energy Lease Area, allowing us to summarize areas of intensive use, and 

environmental predictors of occurrence of key species. 
BACKGROUND: There are 10 wind energy lease areas in the Mid-Atlantic. Wind energy lease 

areas are often in coastal waters (< 30 m depth), where their impacts on coastal marine fish and 

mammals is unknown. To better understand the impacts that installing and maintaining large 

wind turbine structures may have on the local fish species, we developed a baseline dataset 

describing their occurrence and distribution in project areas. Information on the seasonal 

occurrence, spatial distribution, and residency/movement behavior of key species is useful for 

environmental impact assessments and project development. Quantitative estimates of the 

likelihood and degree of impact of offshore wind energy projects may have on species in the 

region can be derived from data collected during this study.

OBJECTIVES: Characterize the seasonal occurrence, spatial distribution and 

residency/migratory behavior of Atlantic sturgeon and winter skate in the Delaware Wind 

Energy lease area, as well as other species detected by acoustic telemetry receiver arrays over a 

two-year period.

METHODS: Twenty-five VEMCO acoustic receiver stations were deployed around the 

perimeter of the Delaware Wind Energy Lease Area between Feb 2017 and Feb 2019. In 

addition, 100 VEMCO acoustic transmitters were deployed in Atlantic sturgeon and winter skate 

in April 2017. Acoustic receivers were downloaded on a bi-monthly schedule (weather 

dependent), and detection data was matched to transmitter codes in the Atlantic Cooperative 

Tagging Network database. The seasonal occurrence, distribution, movement behavior and 

habitat preferences of Atlantic Sturgeon and Winter Skate were quantified from the acoustic 

detection dataset. 

RESULTS: A total of 124,710 acoustic detections from 26 species were recorded at stations 

around the perimeter of the Delaware Wind Energy Lease Area. Atlantic sturgeon were observed 

during all months of the two-year study period, however occurred most frequently in the late 

fall/early winter. Atlantic sturgeon were also most concentrated in the northern portion of the 

study region, except in the late fall/early winter when they were detected throughout the entire 

array. Winter skate occurred less commonly and were concentrated in the shallowest portion of 

the study region. Both species appear to be related to bottom type and topography, which is most 

distinctive in the northern portion of the Delaware Wind Energy Area. 

CONCLUSIONS: It will be difficult for offshore wind energy development projects to 

completely avoid impacting Atlantic Sturgeon, which occur throughout the entire lease area and 

can occur year-round. Predictive species distribution models revealed that Atlantic Sturgeon 

occurrence is predicted by water temperature (surface and bottom), bottom type and topography 

in this region, indicating that it may be an important feeding ground for this species. Winter skate 

are less likely to be impacted by construction efforts, or the presence of these structures, as their 

occurrence is much less common in the lease area. Construction during the summer months 

would likely impact the fewest number of individual animals from all 26 species including our 

focal species, however there is an increased presence of highly migratory and often protected 

elasmobranch species (e.g. blacktip sharks, dusky sharks, sand tiger sharks, tiger sharks, white 

sharks) transiting through the lease area during the summer. 
STUDY PRODUCT(S):

1. BOEM study report: Haulsee, D.E., M.J. Oliver, D.A. Fox. 2020. Occurrence of 

Commercially Important and Endangered Fishes in Delaware Wind Energy Areas Using 

Acoustic Telemetry. US Department of the Interior, BOEM, Environmental Studies 

Program, Sterling, VA. OCS Study BOEM 2020-020. 80 p. 

2. Complete acoustic detection database (124,710 detections) for future analyses. 

* The affiliation of the Principle Investigator(s) may be different than that listed for Project 

Manager(s). 

MAP SHOWING AREA OF STUDY (Figure 1 of 30 of report OCS Study BOEM 2020-020):

Figure 1. Map of study region. 

BOEM Outer Continental Shelf (OCS) wind energy areas off of Delaware and Maryland, and the Delaware Bay 

shipping lanes. Black points represent locations of VEMCO acoustic receiver stations deployed between 27 Feb 

2017 and 23 Feb 2019.