Norfolk/VA Beach Bottlenose Dolphin Photo-ID Surveys

Keywords: Observation, Occurrence,Norfolk-VABeach Vessel,Marine Animal Survey,Marine Biology,Marine mammals,Sea turtles,Visual Sighting,Vessel, Occurrence
Temporal coverage: 2012/2015

Original provider:
HDR Environmental, Operations and Construction, Inc.

Dataset credits:
The U.S. Navy Marine Species Monitoring Program

Abstract:
A combination of visual line-transect survey, photo-
identification (photo-ID), and automated acoustic 
monitoring methods was used to gather important baseline 
information on the occurrence, distribution, and density 
of marine mammals near Naval Station Norfolk (NSN) and 
adjacent areas. The study area was designed to cover areas 
where United States Navy activity is substantial, 
including Chesapeake Bay waters near NSN and Joint 
Expeditionary Base Little Creek-Fort Story, as well as a 
Mine Exercise (MINEX) Area (W-50) in the Atlantic Ocean 
off the coast of Virginia Beach, Virginia. Sixty-one line-
transect surveys were completed in two zones (INSHORE and 
MINEX) between August 2012 and August 2015, with 6,550 
kilometers (km) and 349.6 hours completed on-effort. The 
majority of sightings were of bottlenose dolphins 
(Tursiops truncatus), although humpback whales (Megaptera 
novaeangliae), harbor porpoises (Phocoena phocoena), and 
short-beaked common dolphins (Delphinus delphis) were also 
sighted in the study area on occasion. In addition, 
loggerhead sea turtles (Caretta caretta), leatherback sea 
turtles (Dermochelys coriacea), and a Kemp’s ridley sea 
turtle (Lepidochelys kempii) were sighted during surveys. 
Conventional line-transect analysis of bottlenose dolphin 
sightings showed both spatial and seasonal variation in 
density and abundance, with greatest density in the 
INSHORE zone during fall months. Densities in the INSHORE 
zone were calculated as 3.88 individuals per square 
kilometer (km2) (abundance[N]=1,203) in fall, 0.63 
individuals per km2 (N=195) in winter, 1.00 individuals 
per km2 (N=311) in spring, and 3.55 individuals per km2 
(N=1,101) in summer. Densities in the MINEX zone were 
calculated as 2.14 individuals per km2 (N=1,277) in fall, 
0.06 individuals per km2 (N=37) in winter, 1.53 
individuals per km2 (N=913) in spring, and 1.39 
individuals per km2 (N=829) in summer. Twenty-seven photo-
ID surveys were completed, and a photo-ID catalog was 
created using photos taken during both dedicated photo-ID 
and line-transect surveys through May 2014; it contains 
878 identified individuals to date. Subsequent photos will 
continue to be added and analyzed. One hundred ten 
individuals were re-sighted; however, most re-sightings 
were less than 4 months and 30 km apart. Additional survey 
effort and further analysis will be required before any 
clear movement patterns can be determined. C-POD acoustic 
data-loggers were initially deployed at four sites 
throughout the study area to cover areas of high United 
States Navy activity. Bottlenose dolphins were detected in 
each deployment location during all deployments from 
August 2012 to December 2015. Though deployments did not 
provide consistent coverage in all seasons for all sites 
due to loss of gear, results from two deployment sites 
nearest to NSN showed a greater level of occurrence during 
fall months, and a diel pattern of occurrence with 
increased detections during nighttime hours for three 
deployment sites.

Purpose:
The HDR Marine Species Monitoring (MSM) Team was tasked to 
initiate a monitoring project in coastal waters around 
NSN, JEB-LC, JEB-FS, and the Virginia Beach waterfront, 
including the VACAPES MINEX W-50 training area. The main 
objective is to provide quantitative data and information 
on the seasonal occurrence, distribution, and density of 
marine mammals. Effort was dedicated to working with local 
researchers and employing proven marine mammal monitoring 
and research techniques to accomplish the following:

1. Conduct monthly systematic line-transect surveys to 
determine distribution of marine mammals in the vicinity 
of NSN, JEB-LC, JEB-FS, and the MINEX W-50 area.

2. Conduct monthly photo-identification (photo-ID) surveys 
during summer months to determine the site fidelity and 
distributional patterns of marine mammals utilizing the 
areas listed above.

3. Supplement visual surveys by deploying and retrieving 
four C-POD acoustic recording devices to monitor for 
dolphin echolocation clicks in specific locations.

Supplemental information:
[2019-08-27] New data were appended and some columns with 
empty values were removed. The dataset name is changed by 
dropping the time period part.

This dataset includes sightings from photo-id surveys. No 
images and information on individual animals are provided.

This dataset includes a subset of the data collection for 
the Norfolk-VABeach Vessel surveys.
Other data of the collection are available in the 
following datasets:
<a href="http://seamap.env.duke.edu/dataset/1071">Norfolk/VA Beach Inshore Vessel Surveys 
Nov 2012- Nov 2013</a>
<a href="http://seamap.env.duke.edu/dataset/1072">Norfolk/VA Beach MINEX Vessel Surveys</a>

All the US Navy-funded survey datasets are found in the <a href="http://seamap.env.duke.edu/partner/NAVY">OBIS-SEAMAP US Navy</a> page.