National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

244

3.6 SEA TURTLES

There are seven species of sea turtles worldwide: loggerhead, green, hawksbill, Kemp’s ridley, olive ridley, 

flatback, and leatherback. All but the flatback (which is endemic to northern Australia) are present 

throughout U.S. coastal and marine waters, including all navigationally significant U.S. waters, extending 

seaward to the limits of the EEZ. A list of sea turtle species in the action area, including current status and 

region of occurrence, is provided in Table 3.6-1.

All sea turtles in U.S. waters are protected under the ESA by NMFS while in water and by the USFWS while 

onshore. Under the ESA, a species is considered endangered if it is “in danger of extinction throughout all 

or a significant portion of its range.” A species is considered threatened if it “is likely to become an 

endangered species within the foreseeable future throughout all or a significant portion of its range.” Sea 

turtles and their nests are also protected to varying degrees by some states and localities.

3.6.1 Affected Environment

The following sections provide discussions of sea turtle species including acoustic capability, regional 

distribution, and descriptions of ESA-listed listed species.

The order Testudines includes all turtles and tortoises. The Cheloniidae family includes hard-shelled 

turtles and comprises six of the seven sea turtle species. The Dermochelyidae family lacks a bony shell 

and includes only one sea turtle species, the leatherback. 

Sea turtles are air breathing reptiles that are primarily aquatic, generally coming ashore only to lay eggs. 

Hatchlings immediately enter the sea and migrate to the pelagic zone where they may shelter and feed in 

drift communities for 1 to 15 years. All but two species then return to coastal zones at the early-to-mid 

juvenile stage. The turtles then remain in the coastal zone unless their migration routes to breeding and 

nesting areas include movements through pelagic habitat. The exceptions to this are leatherbacks and 

olive ridleys, which remain in the pelagic zone for the majority of their lives. Adult sea turtles range in size 

from the Kemp’s ridley, measuring about 0.6 m (2 ft) and weighing 45 kilograms (kgs) (100 pounds [lbs]), 

to the leatherback, reaching up to 1.7 m (5.5 ft) and 1,000 kgs (2,200 lbs) (NMFS, No Date-a). All species 

are thought to be long-lived, with life spans expected to range from at least 30 years to over 80 years. Sea 

turtle bodies are fusiform, that is, tapering at the front and rear. This improves their movements in aquatic 

environments but prevents retraction of their heads and limbs. Sea turtle limbs are adapted to aquatic 

movements and feeding. Their diets differ by species and life-stage, including herbivory, carnivory, and 

omnivory. Likewise, feeding strategies also vary by species and life stage. Sea turtles breathe by coming 

to the surface.

All sea turtles are protected by the ESA throughout their ranges. Additionally, four species have critical 

habitat designated for their entire range or one of their constituent DPSs. Table 3.6-1 lists the six species 

of sea turtles and nine DPSs occurring in the action area. Three entire species are listed as endangered 

along with four DPSs. One species is listed as threatened along with the five remaining DPSs.
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

245

Table 3.6-1. Sea Turtles Occurring in the Action Area

DPS

(if applicable) ESA Status Lead Agency Region*

Critical 

Habitat General Habitat

Loggerhead – Caretta caretta

Northwest Atlantic Threatened NMFS, USFWS GAR, SER Yes Nesting: occurs from April to September, peaking in June 

and July. Within the action area, nesting for the Northwest 

Atlantic DPS typically occurs on high energy, narrow, 

steep, coarse-grained beaches from Texas to Virginia. 

Most nesting within the action area occurs within Florida, 

Georgia, South Carolina, and North Carolina. Outside the 

action area, the North Pacific DPS nests in Japan and the 

South Pacific DPS nests mainly in Queensland, Australia.

Post hatchling: local downwellings with floating algae 

and/or seaweed.

Pelagic developmental phase (7-15 years): offshore 

oceanic zone.

Late juvenile and adult: nearshore coastal and/or 

continental shelf.

North Pacific Endangered NMFS, USFWS WCR, AR No

South Pacific Endangered NMFS PIR No

Green - Chelonia mydas

North Atlantic Threatened NMFS, USFWS GAR, SER Yes Nesting: Occurs from June to September. Nesting typically 

occurs on beaches with a sloping platform and minimal 

disturbance. Most nesting within the action area occurs in 

Florida and Hawai’i, with some nesting occurring in the 

U.S. Virgin Islands, Puerto Rico, Georgia, South Carolina, 

and North Carolina.

Pelagic developmental phase (5 to 7 years): offshore 

oceanic zone, pelagic drift communities.

Late juvenile and adult: Nearshore, bays, lagoons, reefs, 

especially areas with seagrass beds.

South Atlantic Threatened NMFS, USFWS SER No

Central North Pacific Threatened NMFS, USFWS PIR No

Central West Pacific Endangered NMFS, USFWS PIR No

Central South Pacific Endangered NMFS, USFWS PIR No

East Pacific Threatened NMFS, USFWS WCR No
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

246

DPS

(if applicable) ESA Status Lead Agency Region*

Critical 

Habitat General Habitat

Hawksbill - Eretmochelys imbricate

-- Endangered NMFS, USFWS GAR, SER, 

WCR, PIR

Yes Nesting: Occurs April to November. Nesting occurs on 

beaches and “pocket” beaches with little or no sand. Most 

nesting within the action area occurs within the U.S. Virgin 

Islands, Puerto Rico, and Hawai’i. Nest sites have also been 

documented in American Samoa and Guam.

Pelagic developmental phase: offshore oceanic zone, 

floating algal mats, flotsam and jetsam drift lines.

Late juvenile and adult: shallow coastal zones, coral reefs, 

high-energy shoals, and mangroves.

Kemp’s Ridley - Lepidochelys kempii

-- Endangered NMFS, USFWS GAR, SER No Nesting: Occurs from April to July. Nesting within the 

action area occurs primarily on Texas beaches of the Gulf 

of Mexico, although nest sites have been documented on 

Atlantic beaches of North Carolina, South Carolina, and 

Florida.

Pelagic developmental phase (1 to 2 years): offshore 

oceanic zone primarily of the Gulf of Mexico but also the 

Atlantic by way of the Gulf Stream, floating Sargassum 

mats.

Juvenile and adult: nearshore, areas of the Gulf of Mexico 

or northwestern Atlantic.

Olive Ridley - Lepidochelys olivacea

-- Threatened NMFS, USFWS SER, WCR, PIR No Nesting: Occurs from June to December up to 3 times in a 

single nesting season. Nesting occurs outside the action 

area in the Pacific beaches of Mexico and Costa Rica; and 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

247

DPS

(if applicable) ESA Status Lead Agency Region*

Critical 

Habitat General Habitat

in Indian Ocean beaches of India, Bangladesh, Myanmar, 

Malaysia, and Pakistan.

Breeding: coastal areas

Juvenile/adult: mainly pelagic, but can inhabit coastal 

areas, bays, and estuaries.

Leatherback - Dermochelys coriacea

-- Endangered NMFS, USFWS All Yes Nesting: Occurs from March to July on beaches. Nesting 

within the action area occurs on the Atlantic coast of 

Florida, the U.S. Virgin Islands, and Puerto Rico.

Juvenile/adult: pelagic

Sources: ECOS, No Date-a; NMFS, No Date-a

*GAR = Greater Atlantic Region (includes the U.S. portions of the Great Lakes, New England, and the mid-Atlantic); SER = Southeast Region (includes the 

southern portion of the U.S. Eastern Seaboard, the U.S. Caribbean Islands [Puerto Rico and the U.S. Virgin Islands], and the Gulf of Mexico); AR = Alaska Region 

(includes Alaskan waters and the Arctic); WCR = West Coast Region (includes coastal California, Oregon and Washington); PIR = Pacific Islands Region (includes 

Hawai’i and territories of the U.S.)
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

248

3.6.1.1 Sound Production and Hearing

NOAA’s Ocean Noise Strategy Roadmap (NOAA, 2016) recognizes that the biological importance of 

hearing in sea turtles has not been studied in great detail, but that it “seems likely that they use sound for 

navigation, to locate prey, to avoid predators, and for general environmental awareness”. It is thought to 

be unlikely that turtles use sound for communication, though recent research is exploring this hypothesis. 

Sea turtle hearing has been inferred from studies of the animals’ physiology and morphology and from 

electrophysiological studies. 

Sea turtle hearing is better suited to aquatic than open-air conditions and varies by species, size, and age, 

with smaller and younger turtles having the broadest sensitivity ranges and larger, older turtles having 

the narrowest. Sea turtle hearing in aquatic conditions generally ranges from 50 Hz to 1600 Hz, with the 

highest sensitivities falling in the 200 Hz to 400 Hz range (BOEM, 2014b; NOAA, 2016; Piniak, 2012; and 

Southwood et al., 2008). Avoidance is generally observed at 166 to 174 dB re 1 μPa and behavioral 

harassment is considered to occur at sound intensities equal to or greater than 175 dB re 1 μPa, though 

studies have been limited and the Bureau of Ocean Energy Management (BOEM) recognized that this 

results in incomplete or unavailable information with regard to sea turtle physiology and behavioral 

response to intense sounds (BOEM, 2014b).

3.6.1.2 Regional Distribution

Sea turtles are found throughout the action area. Like marine mammals, sea turtles are known to make 

wide-ranging movements and may not be present in a specific region year-round; however, some species 

are considered distinct populations and do not migrate as broadly. Range varies by species and DPS, with 

some migrating up to 16,000 km (10,000 mi) per year and diving to nearly 1,200 m (4,000 ft) deep (NMFS, 

No Date-a). The distribution of sea turtles may be influenced by ecological conditions, physical features, 

and seasonal movements. Movements are most often associated with development stage and seasonal 

feeding, breeding, and nesting activities. 

3.6.1.2.1 Greater Atlantic Region

Five of the six sea turtle species in the action area occur in the Greater Atlantic Region, as indicated in 

Table 3.6-1. Only the olive ridley are absent. The loggerhead Northwest Atlantic DPS and green North 

Atlantic DPS are listed as threatened. The hawksbill (rare in this region), Kemp’s ridley, and leatherback 

are listed as endangered. There is no designated critical habitat and few known nest sites in the Greater 

Atlantic Region, although loggerhead sea turtles nests have recently been documented in Delaware and 

Maryland coastal areas.

3.6.1.2.2 Southeast Region

All six of the sea turtle species in the action area occur in the Southeast Region, as indicated in Table 3.6-

1. The loggerhead Northwest Atlantic DPS, green North Atlantic DPS, and olive ridley are listed as 

threatened. The hawksbill, Kemp’s ridley, and leatherback are listed as endangered. Critical habitat is 

designated in the region for leatherback, green, hawksbill, and loggerhead (Figure 3.6-1). Leatherback, 

hawksbill, green, loggerhead, and Kemp’s ridley sea turtles are known to nest in the Southeast region 

(Figure 3.6-1).
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

249

Sources: ECOS, No Date-a; NMFS, No Date-a; SWOT, No Date

Figure 3.6-1. Southeast Region Sea Turtle

Designated Critical Habitat and Nesting Sites

3.6.1.2.3 West Coast Region

Five of the six sea turtle species in the action area occur in the West Coast Region, as indicated in Table 

3.6-1. Only the Kemp’s ridley are absent. The loggerhead North Pacific DPS, hawksbill, and leatherback 

are listed as endangered. The green East Pacific DPS and olive ridley are listed as threatened. Critical 

habitat is designated in the region for leatherback sea turtles (Figure 3.6-2), but there are no known nest 

locations for any species of sea turtle.
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

250

Sources: ECOS, No Date-a; NMFS, No Date-a

Figure 3.6-2. West Coast Region Sea Turtle

Designated Critical Habitat

3.6.1.2.4 Alaska Region

Four of the six species of sea turtles in the action area have ranges or have been sighted in the Alaska 

Region. Leatherback sea turtles have the broadest range in the region, though green sea turtles also have 

a limited range in southeastern areas. Alaska Department of Fish and Game (ADF&G) also lists sightings, 

but no range, of olive ridley and loggerheads (ADF&G, No Date-a). Leatherbacks are listed as endangered 

throughout their range. The loggerhead North Pacific DPS includes the Alaska region and is listed as 

endangered. Though DPS descriptions for green turtles do not extend into the Alaska region, the nearest 

DPSs are the East Pacific, listed as endangered, and Central North Pacific, listed as threatened. Olive ridleys 

are listed as threatened throughout their range. No critical habitat is designated for sea turtles in the 

region, and there are no known sea turtle nest sites.

3.6.1.2.5 Pacific Islands Region

Five of the six sea turtle species in the action area occur in the Greater Atlantic Region, as indicated in 

Table 3.6-1. Only the Kemp’s ridley are absent. The loggerhead South Pacific DPS, green Central West 

Pacific DPS, green Central South Pacific DPS, hawksbill, and leatherback are listed as endangered. The 

green Central North Pacific DPS and olive ridley are listed as threatened. No critical habitat for sea turtles 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

251

has been designated in the Pacific Islands Region, although green, hawksbill, leatherback, and loggerhead 

sea turtles are known to nest there (Figure 3.6-3). 

Sources: ECOS, No Date-a; NMFS, No Date-a, SWOT, No Date

Figure 3.6-3. Pacific Islands Region Sea Turtle Nesting Sites

3.6.1.3 Threatened and Endangered Species

All six species of sea turtles and their constituent DPSs are federally listed in the action area. Four species 

or their constituent DPSs also have designated critical habitat. These species are shown in Table 3.6-1 and 

described in detail below. 

3.6.1.3.1 Loggerhead (Northwest Atlantic, North Pacific, and South Pacific Distinct Population 

Segment)

Loggerhead sea turtles (Figure 3.6-4) can generally be found in temperate and tropical waters around the 

world. Upon hatching, loggerheads swim to sea for up to several days before settling at localized 

downwellings where floating materials, such as rafts of Sargassum, may accumulate. In this habitat, they 

expend little energy while floating and feeding opportunistically on small animals (Conant et al., 2009). 

Currents eventually move the young turtles into the pelagic zone where they remain for 7 to 15 years 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

252

before migrating to coastal areas. As juveniles and adults, loggerheads are primarily carnivorous and have 

large heads with strong jaws with which to feed on benthic invertebrates, whelks, mollusks, horseshoe 

crabs and sea urchins. Loggerheads may take 20 to 30 years to mature and at full growth reach 

approximately 1 m (3 ft) in length and weigh up to 113 kgs (250 lbs). Upon reaching maturity, loggerheads 

nest every 2 to 3 years on the beaches where they hatched. The lifespan of the turtles is thought to be 70 

to 80 years or more (NMFS, No Date-a).

Photo credit: Nathalie Jacque, Solv LLC

Historically, human encroachment on nesting beaches, harvest of eggs, harvest of subadults and adults, 

depredation, insufficiency of protective regulations, and incidental fishing takes led to the decline of 

loggerhead populations. In 1979, loggerheads were listed as threatened under the ESA wherever the 

species occurs (Conant et al., 2009). In 2011, USFWS determined that loggerheads comprise nine DPSs, of 

which four are listed under the ESA as threatened and five as endangered (ECOS, No Date-a). Loggerheads 

continue to face threats from bycatch in fishing gear, ocean pollution and debris, and intentional killing 

(NMFS, No Date-a).

Three DPSs occur in the action area: North Pacific, South Pacific, and Northwest Atlantic. The North Pacific 

DPS includes individuals that hatch on beaches in Japan and spend their entire lives in the north Pacific 

without crossing the equator. After hatching, the turtles initially move in a passive manner with the North 

Pacific gyre, and then use the Kuroshi and North Pacific currents on their developmental migration, which 

serves to isolate them from the South Pacific DPS. As adults, the turtles return to nest on the beaches 

where they were hatched, thus maintaining the pattern of separation. North Pacific DPS turtles forage off 

the west coast of North America as far south as Baja California Sur, Mexico (Conant et al., 2009) and have 

been observed as far north as Alaska (NMFS, No Date-a). The North Pacific DPS is listed as endangered 

and has no designated critical habitat (ECOS, No Date-a). Populations are estimated to be small, declining, 

and at risk of extinction (Conant et al., 2009).

The South Pacific DPS includes individuals hatched mainly in Queensland, Australia, but also in New 

Caledonia, Vanuatu, and Tokelau. These genetically distinct sea turtles are the only loggerheads inhabiting 

the Pacific south of the equator. New hatchlings travel passively generally with the South Pacific gyre and 

spend developmental phases in the central and southeastern Pacific before returning to the west to mate 

and nest (Conant et al., 2009). The South Pacific DPS is listed as endangered and has no designated critical 

habitat (ECOS, No Date-a). Populations are at risk of extinction (Conant et al., 2009).

Figure 3.6-4. Young Loggerhead
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

253

The Northwest Atlantic DPS includes loggerheads hatched primarily in the southeast U.S. and the Yucatan 

Peninsula of Mexico and Central America, and secondarily from other nesting sites throughout the 

Caribbean and western Atlantic as far south as northern South America. Hatchlings and juveniles use the 

North Atlantic gyre for early life stage movements before generally returning to neritic habitats nearby 

the areas where they hatched. Northwest Atlantic DPS juvenile loggerheads have some overlap in 

distribution with Northeast Atlantic and Mediterranean DPSs. Later-stage juveniles and adults inhabit 

neritic zones from Florida to Massachusetts, the Bahamas, Cuba, and the Gulf of Mexico (Conant et al., 

2009). The DPS is listed as threatened and 38 discrete areas of critical habitat have been designated in the 

Gulf of Mexico and the Atlantic (ECOS, No Date-a). Populations are at risk of extinction (Conant et al., 

2009). 

3.6.1.3.2 Green (North Atlantic, South Atlantic, Central North Pacific, Central South Pacific, 

Central West Pacific, and East Pacific Distinct Population Segment)

Green sea turtles (Figure 3.6-5) can be found across broad ranges of the Atlantic and Pacific. Young green 

sea turtles inhabit the pelagic zone for 5 to 7 years before migrating to coastal areas, bays, and lagoons 

for later stages of life. They primarily feed on algae and seagrass, though sponges and invertebrates 

occasionally make up part of their diet. Green sea turtles may take 25 to 35 years to mature and at full 

growth reach approximately 1 m (3-4 ft) in length and weigh up to 160 kgs (350 lbs). Upon reaching 

maturity, they nest every 2 to 5 years. The lifespan of the turtles is thought to be 60 years or more (NMFS, 

No Date-a).

Photo Credit: Ali Bayless, NOAA/NMFS/PIFSC

In 1978, green sea turtles were listed as threatened wherever found except for the breeding colonies in 

Florida and the Pacific coast of Mexico, which were listed as endangered. In 1998, marine critical habitat

was designated around Culebra Island in Puerto Rico (NMFS and USFWS, 2007). In 2016, 11 green sea 

turtle DPSs were designated as endangered or threatened (81 FR 20058, April 6, 2016). Six of these DPSs 

occur in the action area: the threatened North Atlantic, South Atlantic, East Pacific, and Central North 

Pacific DPSs and the endangered Central West Pacific and Central South Pacific DPSs (ECOS, No Date-a). 

Green sea turtles currently face threats from bycatch in fishing gear, ocean pollution and debris, disease, 

harvest of eggs, and intentional killing (NMFS, No Date-a).

The North Atlantic DPS includes turtles that nest and hatch on beaches along the Atlantic, Caribbean, and 

Gulf coasts of Central and North America and islands of the northwest Caribbean, and the Atlantic coast 

of Mauritania. The population is widespread. There are approximately 167,500 nesting females in the DPS 

Figure 3.6-5. Green Sea Turtle
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

254

at 74 known nesting sites, with 79 percent nesting at a single site in Costa Rica. Of the nesting sites with 

enough data to establish population trends, three sites were stable and four were increasing as of 2015 

(Seminoff, 2015).

The South Atlantic DPS includes turtles that nest and hatch along the Atlantic and Caribbean coasts of 

South America, southeast Caribbean islands, and west coast of Africa. The population is widespread. There 

are approximately 63,300 nesting females in the DPS at 51 known nesting sites, with 51 percent nesting 

at a single site in Bissau. Of the nesting sites with enough data to establish population trends, two sites 

were stable and one could not be determined as of 2015 (Seminoff, 2015).

The East Pacific DPS includes turtles that nest and hatch on beaches along the Pacific coasts of North, 

Central, and South America and islands of the eastern Pacific. The population exhibits a limited spatial 

range. There are approximately 20,000 nesting females in the DPS at 39 known nesting sites, with 58 

percent nesting at a single site in Mexico. The only nesting site with enough data to establish a population 

trend was increasing as of 2015 (Seminoff, 2015).

The Central North Pacific DPS includes turtles that nest and hatch on the islands of the Hawaiian 

Archipelago. The population exhibits a limited spatial range. There are approximately 3,800 nesting 

females in the DPS at 13 known nesting sites, with 96 percent nesting at a single site in Hawai’i. The only 

nesting site with enough data to establish a population trend was increasing as of 2015 (Seminoff, 2015).

The Central West Pacific DPS includes turtles that nest and hatch in an area very roughly bounded as 

follows: 41° north to 13° south latitude and 129° east to 175° west longitude. The highest levels of nesting 

in the area include sites in Micronesia, two islands of Japan, Marshall Islands, and Palau. The population 

is moderately dispersed. There are approximately 6,500 nesting females in the DPS at 51 known nesting 

sites, with 22 percent nesting at a single site in Micronesia. The only nesting site with enough data to 

establish a population trend was increasing as of 2015 (Seminoff, 2015).

The Central South Pacific DPS includes turtles that nest and hatch in an area very roughly bounded as 

follows: nine degrees north to 40° south latitude and 171° east to 96° west longitude. This includes a 

portion of New Zealand, Fiji, Tuvalu, Kiribati, French Polynesia, American Samoa, Cook Islands, Tokelau, 

Tonga, and Easter Island, Chile. The population is widespread. There are approximately 167,500 nesting 

females in the DPS at 59 known nesting sites, with 36 percent nesting at a single site in French Polynesia. 

No nesting sites had enough data to establish population trends as of 2015 (Seminoff, 2015).

3.6.1.3.3 Hawksbill

Hawksbill sea turtles (Figure 3.6-6) can generally be found in tropical waters of the Atlantic and Pacific, as 

well as the Gulf of Mexico, Caribbean Sea, and along the east coast of the U.S. as far north as 

Massachusetts. Young hawksbills spend a few years among drift materials in the pelagic zone before 

moving to coastal areas. As adults, the turtles can be found in coral reef, hard bottom, sea grass, algal 

bed, mangrove, and estuary habitats. Hawksbills are omnivorous, feeding on sponges, algae, corals, 

invertebrates, and inorganic material. The shapes of hawksbill mouths and beaks give the turtles their 

name and help them obtain food from small holes and difficult to reach areas of coral reefs. They take 20 

to 35 years to mature and at full growth reach approximately 1 m (30 to 35 in) in length and weigh up to 

70 kgs (150 lbs). Upon reaching maturity, hawksbills nest every 2 to 7 years in the vicinity of beaches 

where they hatched. Hawksbills can migrate from 80 to over 1,600 km (50-1,000 mi) between feeding and 

nesting grounds. The lifespan of the turtles is unknown but expected to be relatively long (NMFS, No Datea; NMFS and USFWS, 2013a).
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

255

Photo credit: Don McLeish, NOAA/NMFS/PIFSC

Historically, a combination of factors led to the decline of hawksbill populations, the most detrimental of 

which was the taking of turtles for their shells. The shells exhibit a unique marbled appearance and were 

the source of “tortoise shell” used in jewelry, handicrafts and other decorative applications. The tortoise 

shell trade led to the near extinction of the species. In 1970, hawksbills were listed as threatened wherever 

the species occurs (ECOS, No Date-a) and trade in their shells has been internationally banned (NMFS, No 

Date-a). In 1982, terrestrial critical habitat for hawksbill was designated in Puerto Rico in the vicinity of 

Isla Mona, Culebra Island, Cayo Norte, and Isla Culebrita. In 1998, marine critical habitat was designated 

around Isla Mona and Isla Munito, Puerto Rico (NMFS and USFWS, 2013a).

Hawksbills currently face threats primarily from habitat loss, but also from bycatch in fishing gear, vessel 

strikes, pollution and debris, intentional killing, and hybridization. Global populations modelled at 88 sites 

showed that all 63 of the sites with conclusive data had population declines over the last 100 years, while 

25 sites were inconclusive. More recently, 41 sites were assessed and showed about two thirds of the 

sites were still in decline, while about a quarter were increasing and the remaining were stable (NMFS 

and USFWS, 2013a). Internationally, the species is currently identified as critically endangered with 

declining populations (IUCN, 2022).

3.6.1.3.4 Kemp’s Ridley

Kemp’s ridley sea turtles (Figure 3.6-7) can generally be found in the Gulf of Mexico and the northwest 

Atlantic as far north as the Grand Banks and Nova Scotia. Nesting occurs on beaches along the Gulf coasts 

of Mexico and the U.S. and at isolated locations along the Atlantic coast from Florida through North 

Carolina (NMFS and USFWS, 2015). Young Kemp’s ridleys move into the pelagic zone of the Gulf of Mexico 

and sometimes the Atlantic and spend 1 to 2 years amongst Sargassum floats. Upon reaching about 20 

cm (8 in) in size the turtles migrate to coastal zones for the remainder of their development and adult 

lives. Kemp’s ridleys are omnivorous as young and early juveniles feeding among Sargassum mats, but 

generally prefer crabs as late-juveniles and adults when inhabiting coastal waters; they may also perform 

scavenging roles. They take about 13 years to mature and at full growth reach approximately 0.7 m (2.25

ft) in length and weigh up to 45 kgs (100 lbs). Upon reaching maturity, Kemp’s ridleys nest every 1 to 3

years en masse in arribadas (large waves of arriving females). The lifespan of the turtles is unknown but 

expected to be at least 30 years (NMFS, No Date-a).

Figure 3.6-6. Hawksbill
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

256

Photo credit: Kate Sampson, NOAA Fisheries

Kemp’s ridley sea turtles were once abundant in the Gulf of Mexico, with a single arribada observed in 

1947 containing up to 40,000 turtles. By the late 1960s, the largest recorded arribadas contained 1,500 to 

5,000 turtles. Nesting sites that hosted tens of thousands of turtles in the 1940s were estimated to be 

used by only 250 females in 1985. The historical decline of Kemp’s ridley populations has been attributed 

to egg collection, killing of nesting females, and bycatch (NMFS and USFWS, 2015). In December 1970,

Kemp’s ridleys were listed as endangered wherever the species occurs (ECOS, No Date-a). No critical 

habitat has been designated for the species.

Although the Kemp’s ridley made a limited recovery from its low in the mid-1980s, overall nests again 

declined from 2009. The turtles currently face threats from chemical pollution, fisheries interactions, and 

habitat degradation and loss (NMFS and USFWS, 2015; NMFS, No Date-a).

3.6.1.3.5 Olive Ridley

Olive ridleys (Figure 3.6-8) are the most numerous of the sea turtles with global estimates of 800,000 

females nesting annually (NMFS, No Date-a). Olive ridleys can generally be found in tropical waters of the 

Pacific and Atlantic, though they have been observed as far north as Alaska. In the Atlantic they are 

generally observed only south of Florida. Olive ridleys do not nest in the U.S. (NMFS and USFWS, 2014).

They are one of two sea turtle species that inhabit pelagic zones throughout their lives, apart from 

migrating to breeding and nesting grounds and occasional instances of populations inhabiting coastal 

waters. Olive ridleys are omnivorous foragers and have been observed over 3,800 km (2,400 mi) from 

shore. They take 7 to 17 years to mature and at full growth reach approximately 0.5m (22 to 31 in) in 

length and weigh up to 45 kgs (100 lbs). Upon reaching maturity, olive ridleys nest yearly en masse in 

arribadas. The lifespan of the turtles is unknown but expected to be relatively long (NMFS, No Date-a).

In 1978, olive ridleys were listed as threatened wherever the species occurs except for the endangered 

breeding colony populations on the Pacific coast of Mexico (ECOS, No Date-a). No critical habitat has been 

identified for olive ridleys.

Endangered olive ridley populations in Mexico seem to have stabilized. Threatened populations in the 

eastern Pacific are in decline at some nesting beaches, while they are stable or increasing at others, with 

too little data to assign an overall trend. Threatened populations in the western Atlantic are very small, 

with some nesting populations declining and others increasing (NMFS and USFWS, 2014). Olive ridley 

Figure 3.6-7. Kemp’s Ridley Sea Turtle 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

257

populations continue to face threats from bycatch in fishing gear, vessel strikes, pollution and debris, 

harvest of eggs, and killing of adults (NMFS, No Date-a).

Source: World Wildlife Fund

3.6.1.3.6 Leatherback

Leatherback sea turtles (Figure 3.6-9) can generally be found in very broad ranges of the Atlantic and 

Pacific, with known ranges along nearly the entire coastline of the continental U.S., Hawai’i, Puerto Rico, 

the U.S. Virgin Islands, and observations as far north as Alaska (NMFS and USFWS, 2013b). They are one 

of two sea turtle species that spends the majority of its life in pelagic habitat apart from nesting. 

Leatherbacks’ mouths are adapted to their carnivorous diet of soft-bodied jellyfish and salps (planktonic 

tunicates). It is believed that the turtles take 9 to 29 years to mature. At full growth leatherbacks reach 

approximately 1.5 m (4.5 to 5.5 ft) in length and weigh up to 1,000 kgs(2,200 lbs). Upon reaching maturity, 

they nest every 2 to 3 years, often on different beaches. The turtles can migrate up to 16,000 km (10,000 

mi) each year, including up to 6,000 km (3,700 mi) each way to and from foraging and nesting grounds. 

Leatherbacks can dive to almost 1,200 m (4,000 ft) below the ocean surface. The lifespan of the turtles is 

unknown but expected to be relatively long (NMFS, No Date-a).

Photo credit: Dru Devlin, NOAA

In 1970, leatherbacks were listed as endangered wherever the species occurs. In 1978, terrestrial critical 

habitat was designated in the U.S. Virgin Islands on the southwestern side of St. Croix at Sandy Point 

National Wildlife Refuge, and the following year marine critical habitat was designated along the same 

Figure 3.6-8. Olive Ridley Sea Turtle

Figure 3.6-9. Leatherback Sea Turtle
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

258

coast. In 2012, additional marine critical habitat was designated off the coasts of California, Oregon, and 

Washington (NMFS and USFWS, 2013b).

Leatherbacks currently face threats from habitat alteration and loss, bycatch in fishing gear, vessel strikes, 

pollution and debris, harvest of eggs, intentional killing (NMFS, No Date-a), and depredation (NMFS and 

USFWS, 2013b). Eastern Pacific populations of leatherbacks have collapsed, while Atlantic populations 

seem to be stable or increasing. This could be due to more consistent availability and quality of forage in 

the Atlantic resulting in higher reproduction rates (NMFS and USFWS, 2013b).

3.6.2 Environmental Consequences for Sea Turtles

This section discusses the potential impacts on sea turtles, all of which are ESA-listed, and sea turtle 

habitat of Alternatives A, B, and C. Activities described in Sections 2.4.1 through 2.4.13 that occur on NOS 

projects and that could be expected to have impacts on sea turtles and their habitats in the action area

include crewed vessel operations, anchoring, ROV and autonomous vehicles, use of echo sounders, use 

of ADCPs, use of acoustic communication systems, use of sound speed data collection equipment, 

operation of drop/towed cameras and video systems, collection of bottom grab samples, tide gauge

installation/maintenance/removal, GPS reference station installation, and SCUBA operations.

3.6.2.1 Methodology

The factors from NOS activities that could impact sea turtles and sea turtle habitat include: (1) active 

underwater acoustic sources (e.g., echo sounders, ADCPs, and acoustic communication systems); (2) 

vessel and equipment sound (e.g., from surface vessels, ROVs, and autonomous vehicles); (3) vessel 

presence and movement (e.g., surface vessels, ROVs, and autonomous vehicles); (4) vessel wakes (e.g.,

from surface vessels; ROVs; and autonomous vehicles); (5) accidental leakage or spillage of oil, fuel, and 

chemicals into surrounding waters (e.g., from vessel operations); (6) underwater activities (e.g., use of 

underwater survey equipment; anchors; and divers); and (7) onshore activities (e.g., installation, 

maintenance, and removal of tide gauges and GPS reference stations). These potential impact causing 

factors and their associated impacts on sea turtles and sea turtle habitat are discussed below. Note that 

use of the term “sea floor” in the analysis below also includes lake and river bottoms where NOS activities 

could occur.

As discussed in Section 3.2.2, significance criteria were developed for each resource to provide a 

structured framework for assessing impacts from the alternatives and the significance of the impacts. The 

significance criteria for impacts to sea turtles were developed to encompass the context and intensity of 

NOS activities as they relate to direct and indirect impacts to sea turtles and designated critical sea turtle 

habitat. The significance criteria for sea turtles are shown in Table 3.6-2.

Table 3.6-2. Significance Criteria for the Analysis of Impacts to Sea Turtles

Impact 

Descriptor Context and Intensity

Significance 

Conclusion

Negligible

Impacts to sea turtles would be limited to temporary (lasting 

several hours) behavioral disturbances to individuals located 

within the project area. No mortality or debilitating injury to any 

individual sea turtle would occur. There would be no 

displacements of sea turtles from preferred breeding and feeding 

areas, nesting beaches, or migratory routes. Impacts (e.g., 

Insignificant
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

259

Impact 

Descriptor Context and Intensity

Significance 

Conclusion

increased water turbidity, displacement of marine 

macroinvertebrate prey) on sea turtle habitat would be 

temporary with no lasting damage or alteration. 

Minor

Impacts to sea turtles would be temporary or short-term (lasting 

several days to several weeks) and within the natural range of 

variability of species’ populations, habitats, and the natural 

processes sustaining them. This could include non-lifethreatening injury to individual sea turtles and small short-term 

disruptions of time-sensitive behaviors such as breeding, nesting, 

or the emergence and dispersal of hatchlings. Displacement of 

sea turtles from preferred breeding and feeding areas, nesting 

beaches, or migratory routes would be short-term and limited to 

the project area and immediately surrounding areas. Any 

resulting increased competition, additional energy expenditure, 

or loss of hatchlings would not affect overall sea turtle population 

numbers or demographic structure. Impacts on habitat (e.g., 

short-term displacement of marine macroinvertebrate prey, 

increased turbidity) would be easily recoverable with no longterm or permanent damage or alteration. 

Moderate

Impacts to sea turtles would be short-term or long-term (lasting 

several months or longer) and outside the natural range of 

variability of species’ populations, habitats, and the natural 

processes sustaining them. This could include debilitating injury 

or mortality and some short-term disruption of time-sensitive 

behaviors such as breeding, nesting, or the emergence and 

dispersal of hatchlings. Behavioral responses and displacement 

would be expected from individual sea turtles within the project 

area, its immediate surroundings, or beyond. Long-term 

displacement of individuals from preferred breeding and feeding 

areas, nesting beaches, or migratory routes would occur. 

Resulting increased competition and energy expenditure would 

cause losses of breeding or egg-bearing adults and hatchlings, but 

not at large enough scales to negatively impact overall sea turtle 

population numbers or demographic structure. Impacts would 

not threaten the continued existence of any species. Habitat 

would be damaged or altered potentially over the long term (e.g., 

degradation of seagrass beds) but would continue to support 

dependent species. 

Major

Impacts to sea turtles would be short-term or long-term and well 

outside the natural range of variability of species’ populations, 

habitats, or the natural processes sustaining them. This could 

include extensive (i.e., affecting a large proportion of the local 

population), life-threatening, or debilitating injury and mortality, 

and substantial disruption of time-sensitive behaviors such as 

breeding, nesting, or the emergence and dispersal of hatchlings. 

Significant
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

260

Impact 

Descriptor Context and Intensity

Significance 

Conclusion

Long-term displacement of sea turtles from preferred breeding or 

feeding areas, nesting beaches, or migratory routes would occur 

within project areas, their immediate surroundings, and beyond. 

Behavioral disruptions and displacement would result in the loss 

of breeding and egg-bearing adults and hatchlings due to 

increased competition or energy expenditure at scales large 

enough to affect overall sea turtle population numbers or 

demographic structure. Full recovery of sea turtle populations 

would not be expected to occur in a reasonable time. Habitat 

would be degraded over the long term or permanently such that 

it would no longer be able to support dependent populations of 

sea turtles. 

3.6.2.2 Alternative A: No Action - Conduct Surveys and Mapping for Coastal and 

Marine Data Collection with Current Technology and Methods, at Current

Funding Levels

Impacts of Alternative A are discussed below by impact causing factors for sea turtles and their associated 

habitat. Under Alternative A, excluding survey effort in the Great Lakes which would not impact sea 

turtles, NOS survey effort would continue to cover a total of 2,633,374 nm (4,877,009 km) across all five 

regions over the five-year period. Although the survey effort under Alternative A would vary by year (see 

Table 3.5-6), approximately 47 percent of the total linear nautical miles surveyed over the five-year period

would continue to be in the Southeast Region. The survey effort in each of the other four regions would 

continue to be approximately 10 percent of the total survey effort. A slightly higher level of effort would 

occur in the Alaska Region, which contains approximately 18 percent of the total survey effort, but this 

area is only rarely visited by sea turtles. In general, it is expected that level of effort and overall impacts 

trend together (i.e., greater impacts where the survey effort is higher), but there are other factors, such 

as location and depth of surveys, hearing frequency of the animals, and population density of sea turtles, 

that add nuance to this trend.

The analysis of impacts on sea turtles considers all of the impact causing factors introduced above and 

their impacts on sea turtles and sea turtle habitat. Potential impacts could occur in all of the geographic 

regions. All regions include several sea turtle species and designated critical habitat. The Pacific Islands 

Region contains the greatest number of sea turtle species, and the Greater Atlantic and Southeast Regions 

contain the most designated critical habitat areas (see Table 3.6-1). 

3.6.2.2.1 Active Underwater Acoustic Sources

Active underwater acoustic sources are used to survey a variety of ocean features and could cause impacts 

to sea turtles from the propagation of underwater sound. The intermittent acoustic pulses used in NOS 

active surveying range from 0.5 to 1,200 kHz and decrease in intensity with distance from the vessel used 

by NOS; acoustic characteristics of the active acoustic underwater equipment used by NOS are detailed in 

Section 2.4. As such, acoustic pulses are typically considered a potential temporary disturbance limited to 

the immediate vicinity of the vessel used by NOS. Sea turtles are low frequency specialists with a 

generalized hearing range of 30 to 2,000 Hz (0.03 to 2 kHz) and are most sensitive to sound between 200 

and 400 Hz (0.2 and 0.4 kHz) (BOEM, 2014b; NMFS, 2018b; NOAA, 2016; Piniak et al., 2012; and 

Southwood et al., 2008). Hearing below 80 Hz is less sensitive but still possible (Lenhardt, 1994). Sea 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

261

turtles may be able to hear low frequency sources that go down to 0.5 kHz. These low frequency sources 

are used in deeper water, so animals exposed would likely be farther away from the source. However, 

underwater sound produced by active underwater acoustic sources would mostly be at frequencies 

reaching up to orders of magnitude above the documented sea turtle hearing range and would therefore 

be imperceptible to sea turtles and unlikely to cause direct injury, hearing threshold shifts, auditory 

masking, or behavioral changes. 

Similarly, active underwater acoustic sources are not perceptible to sea turtle macroinvertebrate prey 

(see Section 3.8.2.2.1.1) and would not affect any other characteristics of sea turtle habitat, including 

designated critical habitat. Sea turtles and their prey are expected to return to project areas after the 

completion of NOS activities and are not expected to experience any long-term changes in habitat 

availability, habitat use, or energy expenditure. Any resulting impacts from active acoustic underwater 

sources to sea turtles and sea turtle habitat, including designated critical habitat, would continue to be 

potentially adverse, but negligible and therefore insignificant. 

3.6.2.2.2 Vessel and Equipment Sound

Vessel and equipment sound (hereafter vessel sound) represent the majority of the ambient ocean 

auditory environment and are becoming more prominent with increased human marine activity. Vessel 

sound is a combination of tonal sounds (sounds with discrete frequencies such as music notes) and 

broadband sounds (sounds with a combination of many frequencies such as a choir harmonizing) 

(Richardson et al., 1995), which respectively contribute to hearing threshold shifts and acoustic masking. 

Vessel sound ranges in frequency from 10 Hz to 10 kHz and is generated predominantly through propeller 

operation, including cavitation, singing, and propulsion. The intensity of the sound received by sea turtles 

is dependent on the size and speed of the vessel in question and the distance of the sea turtle from the 

vessel. Vessel sound has the potential to disrupt normal sea turtle behavior because of their high hearing 

sensitivity between 200 and 400 Hz.

Underwater sound has the potential to impact sea turtles through hearing threshold shifts or auditory 

masking. Hearing threshold shifts refer to changes in the hearing range of an organism due to exposure 

to high intensity sounds. Threshold shifts can be short-term or long-term depending on the intensity of 

the sound exposure and can result in permanently reduced hearing capabilities of the affected organism. 

Although hearing threshold shifts in sea turtles are not well studied, the U.S. Navy estimates that exposure 

to sound intensities of 189 dB and 204 dB could respectively cause temporary and permanent threshold 

shifts in sea turtles (Navy, 2017b). These estimates were derived using the best available data on sea turtle 

hearing thresholds and mathematical relationships of threshold shifts in similar species. However, the 

vessels used by NOS typically produce source levels of 130 to 160 dB while transiting, and only larger 

vessels outside the scope of this Final PEIS, such as tankers or icebreakers, emit sound with the potential 

to cause threshold shifts in sea turtles (Erbe, 2013; Erbe et al., 2019). Note that this discussion of impacts 

on sea turtles from sound intensity (measured in dB) should not be confused with impacts from sound 

frequency (measured in Hz and kHz); see discussion of underwater sound in Section 3.0. Auditory masking 

refers to those sounds which do not cause direct changes to hearing thresholds, but have the potential to 

obscure ecologically relevant sounds to sea turtles. Masking sounds can interfere with the acquisition of 

prey or mates, the avoidance of predators, and the identification of appropriate nesting sites. There is a 

small possibility that sound from vessels used by NOS could contribute to auditory masking, but it is 

unclear whether masking would realistically have any effect on sea turtles since the role of hearing in sea 

turtle ecology is unknown; there are no quantitative data demonstrating masking effects for sea turtles 

(BOEM, 2014b).
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

262

Underwater sound intensities of 175 to 176 dB, which are roughly equivalent to the airborne sound 

intensity of a motorcycle engine, evoke erratic behavioral changes in green and leatherback turtles,

including evasive maneuvers such as diving or changes in swimming direction or speed (McCauley et al., 

2000a). Source levels as low as 166 dB can induce avoidance behaviors in sea turtles and may temporarily 

displace them from project areas. Although sound produced by vessels used by NOS would typically be 

outside of this range, source levels may vary by 20 to 40 dB within a ship class due to variability in design, 

maintenance, and operational parameters (Simard et al., 2016) and could potentially elicit behavioral 

responses in sea turtles. However, vessel sound attenuates quickly towards the surface of the water 

column and would not likely be perceptible to sea turtles outside several meters of the immediate vicinity 

of the vessel or persist after the conclusion of vessel activity. As such, any behavioral changes and 

displacements would last only for the duration of vessel activity within a given area and would not cause 

any long-term or permanent changes in sea turtle habitat use, prey availability, or competition.

Vessel sound could potentially have an adverse effect on sea turtle habitat, including designated critical 

habitat, through the disturbance and displacement of prey populations. Sea turtles, depending on the

species, eat seagrasses, algae, fish eggs, and marine macroinvertebrates such as sponges, sea squirts, 

squid, shrimp, crabs, jellyfish, cuttlefish, or sea cucumbers. Marine invertebrates, including squid, jellyfish, 

and cuttlefish, are sensitive to low frequency sound ranging from 50 to 400 Hz, although the exact range 

of invertebrate sound perception is unknown (Mooney et al., 2010; Solé et al., 2016). These important 

sea turtle prey species could temporarily be disturbed or displaced from project areas by vessel sound 

(see Section 3.8 Aquatic Macroinvertebrates). However, displacement would likely only last for the 

duration of vessel operation in the immediate area, and vessel sound is not expected to cause any longterm changes in marine invertebrate behavior or habitat use. Any increased foraging effort, competition, 

or energy expenditure resulting from displacement of prey species is not expected to substantially affect 

sea turtles. 

Vessel sound would likely only displace sea turtles and prey within the immediate vicinity of vessels used 

by NOS and would not cause any mortality or direct injury to sea turtles. Sea turtles and their prey are 

expected to return to project areas after the completion of NOS activities and are not expected to 

experience any long-term changes in habitat availability, habitat use, or energy expenditure. Sound is a 

common byproduct of oceanic vessel activity, and the impacts created by sound from vessels used by NOS 

would be indistinguishable from those produced by all other vessels. As such, the impacts to sea turtles 

and sea turtle habitat, including designated critical habitat, from vessel and equipment sound generated 

during NOS activities would continue to be adverse, negligible, and therefore insignificant. 

3.6.2.2.3 Vessel Presence and Movement

Although many NOS projects involve vessel operations and activity, they comprise only a very small 

proportion of the total amount of vessel operations within the action area (see Section 2.4.1). As such, 

the resulting impacts of vessel operations on sea turtles only contribute marginally to the overall impact 

of all vessel presence and movement within a given area. Nevertheless, vessel presence and movement 

as a result of NOS projects could cause sea turtle–vessel interactions including visual disturbance, vessel 

strikes, underwater turbulence from vessel wakes, and reduction or displacement of sea turtle prey. To 

minimize turtle-vessel interactions, if one or more sea turtles is sighted while the vessel is underway, 

attempts would be made to maintain a distance of 45 m (50 yards) or greater whenever possible. 

Much like vessel sound, the visual presence of vessels used by NOS could disrupt normal sea turtle 

behavior and displace individuals from project areas. Very little research exists on sea turtle responses to 

vessel disturbance, but one study suggests that sea turtles may habituate to vessel sound and may be 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

263

more likely to respond to the presence of vessels (Hazel et al., 2007). The visual presence of vessels used 

by NOS in a given area could potentially cause behavioral changes in nearby sea turtles, including evasive 

maneuvers such as diving or changes in swimming direction or speed. Sea turtles would also likely be 

temporarily displaced from project areas while vessels are present. However, only sea turtles within 

approximately 10 m (33 ft) of vessels appear to alter their behavior, regardless of the primary vessel 

stressor (i.e., sight or sound) motivating the response (Hazel et al., 2007). These behavioral changes and 

displacements would last only for the duration of vessel activity within a given area and would not cause 

any long-term or permanent changes in sea turtle habitat use, prey availability, or competition. Vessels 

operating at night would also use the appropriate lighting necessary to comply with navigation rules and 

best safety practice in order to avoid visual disturbances to nesting sea turtles and emerging hatchling. As 

such, increased evasive behavior and additional energy expenditure as a result of vessel presence is not 

expected to harm individuals or the population.

Vessels used by NOS within the action area could potentially collide with sea turtles, resulting in 

debilitating injury or death of individuals. Propeller and collision injuries to sea turtles arising from 

interactions with boats and ships are relatively common; 20.5 percent of observed leatherback sea turtles 

in the Atlantic Ocean and Gulf of Mexico had sustained propeller injuries in 2004 (NMFS and USFWS, 

2008). The sea turtle collision probability of any vessel is contingent upon its size and speed. Larger, 

relatively slow-moving vessels are less likely to strike sea turtles than smaller vessels travelling at higher 

speeds because turtles more easily recognize and avoid larger, slow-moving vessels. Given the low speed 

and small size of most vessels used by NOS (see Section 2.4.1) and NOS would constantly monitor for 

protected species, collisions are expected to be generally avoided during NOS projects and during transit 

to a project site. However, behavioral observations of sea turtle vessel avoidance reveal that some sea 

turtles may be susceptible to vessel strikes at speeds as low as two knots (Hazel et al., 2007). Regardless, 

the overall probability of collision between vessels used by NOS and sea turtles remains low given that

adult and sub-adult sea turtles only spend small proportions of their time at the water surface where they 

are most susceptible to vessel strikes. Poor visibility conditions at night would impede the ability of vessels 

used by NOS and sea turtles to recognize and avoid each other, potentially resulting in a higher risk of 

vessels striking sea turtles engaged in nocturnal feeding, mate searching, and movement towards nesting 

beaches. Additionally, project areas would be continuously monitored for protected species at all times 

during vessel operations. However, as sea turtles are predominantly diurnal and do not surface often 

during the night, and because NOS operations are uncommon at night, the overall probability of nighttime 

collisions is expected to be very low. As such, the probability of vessels used by NOS striking sea turtles 

would be very low. 

Wakes associated with the movements of vessels used by NOS could also disturb the water column and 

adversely impact sea turtles within the project area. Moving vessels would displace large amounts of 

water, and the resulting underwater turbulence could disturb and displace nearby sea turtles. However, 

this displacement would be temporary, and would occur only while vessels used by NOS are within 10 m 

(33 ft) of sea turtles (Hazel et al., 2007). Any evasive behavior and energy expenditure as a result of water 

disturbance from vessel wakes is not expected to substantially affect individuals or populations; sea 

turtles are expected to return to preferred feeding, breeding, and migratory routes upon departure of the 

vessel used by NOS. Impacts to sea turtles as a result of displacement would likely increase if the frequency 

of disturbance increases (i.e., spatially or temporally replicated passes in a given project area), but NOS 

projects would be coordinated carefully to ensure project areas are not repeatedly sampled unnecessarily 

(see Section 2.2). 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

264

The presence and movement of vessels used by NOS could affect sea turtle habitat, including designated 

critical habitat, through the disturbance and displacement of macroinvertebrate prey. As with active 

underwater acoustic sources and vessel sound discussed above, vessel presence and movement would 

likely displace motile (capable of self-powered motion) macroinvertebrate prey species from project areas 

through underwater visual disturbance or turbulence from wakes. Prey are expected to return to project 

areas immediately following vessel activity, and any increased foraging effort, competition, or energy 

expenditure resulting from the displacement of macroinvertebrate prey is not expected to harm sea turtle 

individuals or overall sea turtle populations. 

Any injury or death to sea turtles would constitute a moderate or greater impact, depending on the 

species, given the protection status afforded to sea turtles by the ESA. However, there is a very low 

likelihood of vessel strikes, displacement of sea turtles and their prey by vessel presence or wakes would 

be limited to the immediate project vicinity, and the duration of NOS projects would be on the order of 

hours, days, or weeks, although a small number of projects may last several months spread across years 

(see Section 2.4.1). As such, any resulting impacts to individual sea turtles or to overall sea turtle

populations, sea turtle prey, and their respective habitat availability would be well within the natural 

range of variability. Furthermore, vessels used by NOS only represent a negligible portion of overall vessel 

traffic within the U.S. EEZ, and the impacts created by the movement of vessels used by NOS would be 

indistinguishable from those produced by all other vessels. Overall, the effects of vessel presence and 

movement on sea turtles and their habitat, including designated critical habitat, would continue to be

adverse, negligible to minor, and therefore insignificant. 

3.6.2.2.4 Accidental Leakage or Spillage of Oil, Fuel, Chemicals, and Waste

Accidental oil, fuel, or chemical spills as a result of NOS projects could affect sea turtles through various 

pathways including direct contact, inhalation of the oil or fuel and its volatile components, and ingestion. 

Several aspects of sea turtle biology and behavior place them particularly at risk for exposure to spilled 

fuels, including lack of avoidance behavior, indiscriminate feeding in areas where ocean currents 

converge, and inhalation of large volumes of air before dives (Shigenaka et al., 2021). Turtles surfacing 

within or near an oil or fuel release may inhale petroleum vapors, causing respiratory stress. Ingested oil 

or fuel, particularly the lighter fractions, can be acutely toxic to sea turtles. The direct exposure of sensitive 

tissues (e.g., eyes or other mucous membranes) and soft tissues to diesel fuel or volatile hydrocarbons 

could produce irritation and inflammation. Oil and fuel also can adhere to turtle skin or shells, prolonging 

and exacerbating the direct effects of tissue exposure. Larger spills would contaminate areas beyond the 

immediate project area and increase the likelihood of sea turtle exposure to volatile chemicals and 

resulting injury or mortality. However, the vast majority of spills or releases are confined to the immediate 

project area and would disperse quickly within the ocean typically within a day or less (NOAA, 2020a). A 

small spill would not be likely to result in the death or life-threatening injury of individual turtles or 

hatchlings, or the long-term displacement of adult turtles from preferred feeding, breeding, or nesting 

habitats or migratory routes. 

All crewed vessels produce some waste through normal operations; during activities, vessels operated by 

NOS could accidentally lose or discard debris, a major form of marine pollution (Laist, 1997). Vessels used 

by NOS would generate some waste in the form of metal, wood, glass, paper, and plastic, primarily 

through galley and food service operations on larger vessels. Marine debris can potentially impact sea 

turtles through entanglement and ingestion. Entanglement with marine debris is a far more likely cause 

of mortality to sea turtles than its ingestion; loggerhead turtles have been found entangled in debris 

ranging from fishing lines to onion sacks (NMFS and USFWS, 2008). Impacts from discarded trash and 

debris are expected to be avoided through vessel operators’ required compliance with USCG and EPA 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

265

regulations. In addition, no intentional vessel discharges would occur if a protected species is sighted 

within 91 m (100 yds) of the vessel used by NOS, and all MARPOL discharge protocols would be followed.

Accidental discharge of oil, fuel, chemicals, or waste could potentially affect sea turtle habitat, including 

designated critical habitat, through the contamination of prey and sensitive foraging areas. Important sea 

turtle food sources, such as macroinvertebrates and seagrasses, could become contaminated and 

bioaccumulate (concentrate ingested substances in tissue) spilled contaminants. These food resources 

would be additional routes for exposure to and ingestion of volatile chemicals by sea turtles. Breeding 

and nesting habitat along coastlines adjacent to spills could also potentially be degraded as spilled 

substances are washed ashore. However, it is unlikely that a small spill in the ocean would reach turtle 

nests, which are usually located above the high tide line. Large spills that extend beyond the immediate 

project area have a much greater likelihood of degrading sensitive sea turtle foraging and nesting habitat 

and could result in long-term changes in sea turtle habitat availability. Assuming proper adherence to 

waste disposal regulations, prey species would very rarely be exposed to trash and debris from NOS 

projects. As such, the exposure of sea turtles to oil, fuel, chemicals, or waste from contaminated prey 

would be negligible and is not expected to threaten individual sea turtles or sea turtle populations.

Such accidents may be caused by equipment malfunction, human error, or natural phenomena and are 

not expected during the course of NOS operations. In the unlikely event of an accidental spill, there would 

be very low likelihood for contaminants to make contact with the water because vessel operations 

personnel are required to respond immediately using established spill response procedures. For example, 

on NOAA fleet vessels, in the event of an oil, hazardous substance, or marine pollutant spill, the 

Commanding Officer takes appropriate action to minimize the effects of the spill. OMAO Procedure 0701-

06 VRP/SOPEP provides policy and guidance to all NOAA vessels regarding oil pollution emergency 

planning and response, in accordance with MARPOL 73/78, Annex I. The plan contains all the information 

and instruction required for responding to shipboard oil spills, such as general spill mitigation and 

response, shipboard spill mitigation and response, reporting requirements, completing Corrective Action 

Assessments, trainings, drills, and exercises. This plan has been approved by the USCG, and complies with 

the Oil Pollution Act of 1990 and Federal Water Pollution Act of 1973.

Any injury or death to sea turtles would constitute a moderate or largerimpact, depending on the species, 

given the protection status afforded to sea turtles by the ESA, NMFS, and USFWS. However, there is only 

a very low likelihood of small spill occurrence and no possibility of large spills given the size of vessels used 

by NOS. Displacement of sea turtles and their prey by small amounts of discharged oil, fuel, chemicals, or 

waste would likely be limited to the immediate vicinity of vessels and dispersal period of the discharged 

substance. Any resulting impacts to individual sea turtles or sea turtle populations, sea turtle prey, and 

their respective habitat availability would be well within the natural range of variability. Small spills are a 

normal byproduct of oceanic vessel activity, and the impacts created by potentially small NOS spills would 

be indistinguishable from those produced by all other vessels. As such, adverse impacts to sea turtles and 

sea turtle habitat, including designated critical habitat, from accidental leakage or spillage of oil, fuel, 

chemicals and waste would continue to be adverse, negligible to minor depending on the spill size and 

location, and therefore insignificant. 

3.6.2.2.5 Underwater Activities

The vast majority of NOS underwater activities would result in temporary disturbance to the water 

column, potentially impacting sea turtles. The lowering and raising of echo sounders, anchors and chains, 

CTD equipment, sound speed data collection equipment, camera and video systems, and grab samplers 

could temporarily displace sea turtles and disrupt their behavior. Any evasive behavior and energy 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

266

expenditure as a result of water disturbance is not expected to affect individuals or populations in the 

long term; if displaced, sea turtles are expected to return to preferred feeding, breeding, and migratory 

routes and resume normal activities after completion of NOS projects in the area. The impact on sea 

turtles should be minimal and cease when the anchoring system or equipment comes to rest or is taken 

out of the water. However, sea turtles are particularly sensitive to disturbances during seasonal breeding 

periods and within coastal areas adjacent to nesting habitat. Repeated, prolonged underwater activities 

in these areas could disrupt important, time-sensitive behaviors, which would likely have more severe or 

more intense adverse effects on turtles. 

Similarly, a number of NOS activities involve trailing the equipment listed above with lines or wire behind 

and beneath vessels used by NOS, which poses a risk of entangling nearby sea turtles. Although sea turtle 

entanglement with marine debris is recognized as a major source of mortality, entanglement with 

equipment is not well studied and is typically limited to fishery-related bycatch (Duncan et al., 2017). 

Anecdotal accounts indicate that sea turtle mortalities have resulted from entanglement with trailed 

seismic equipment off the West Coast of Africa (Nelms et al., 2016), which suggests that sea turtles could 

also become entangled in the various trailed equipment used by NOS during projects. Entangled sea 

turtles may drown or starve or be struck by vessels due to restricted mobility in addition to potentially 

suffering physical trauma and/or systemic infections (NMFS, 2018b). However, the trailed equipment 

used during NOS would only be submerged for periods of time ranging from minutesto hours (see Section 

2.4), limiting the potential exposure to sea turtles and possible entanglement. Trailed equipment is also 

typically more conspicuous than common entanglement hazards such as discarded monofilament fishing 

line, and nearby sea turtles would likely be able to recognize and avoid trailing equipment. Furthermore, 

the majority of trailed equipment would stay within meters of the towing vessel and would only 

potentially impact sea turtles within close range; however, they would likely be displaced by the visual 

disturbance and sound of the vessel itself (Section 3.6.2.2.2) before they could interact with any trailed 

equipment. As such, entanglement with trailed NOS equipment is not expected to be a substantial threat 

to sea turtles.

SCUBA diving activities are included in 248 NOS projects under Alternative A (see Table 2.6-1) and have 

the potential to adversely affect sea turtles through behavioral responses to diver presence. Although 

SCUBA diving is largely considered a non-invasive activity, exposure to human presence can alter sea turtle 

behavioral patterns. Recent studies demonstrate that sea turtles are susceptible to disturbance by divers 

(Schofield et al., 2006; Dunbar et al., 2008) and spend less time foraging when divers are present (Hayes 

et al., 2017). These behavioral changes would only last for the duration of diver activity in the immediate 

area and any increased energy expenditure, competition, or nutritional deficiencies are not expected to 

affect individual sea turtles or the overall sea turtle population. Prolonged or repeated disturbances in 

seagrass habitat, migratory routes, or sensitive coastal areas adjacent to nesting beaches could disrupt 

important, time-sensitive behaviors, which would likely have more severe, adverse effects on turtles.

Underwater activities including anchoring, bottom sampling, drop cameras, and mobile ADCPs can disturb 

the sea floor, increasing sedimentation and potentially adversely affecting sea turtle habitat, including 

designated critical habitat. Seagrass and macroalgae, important sources of forage for some species of sea 

turtle, can be directly uprooted by disturbance to the sea floor and are highly sensitive to changes in water 

quality. Seagrass fields in the Southeast and Greater Atlantic Regions are designated as critical habitat for 

turtles; direct destruction of seagrass in these areas would adversely impact sea turtle populations.

Furthermore, reductions in water quality can also result in displacement of marine macroinvertebrate sea 

turtle prey. However, seafloor disturbance would be limited to relatively small portions of a given project 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

267

area and any resulting changes to water quality would be quickly dissipated by the prevailing ocean 

currents in the area.

To minimize or avoid the potential adverse effects of underwater activities, mitigation measures would 

be implemented, including (also see Appendix D):

• NOS would not drag anchor chains and would ensure that anchors are properly secured so as to 

minimize bottom disturbance.

• Deployment of all autonomous systems, instruments, and divers would be suspended if any 

protected species is sighted within 92 m (100 yards) of the vessel. Work already in progress may 

continue if the activity is not expected to adversely affect the animal.

• During all buoy deployment and retrieval operations, buoys would be lowered and raised slowly 

to minimize risk to listed species. In addition, observers would monitor for listed species in the 

area prior to and during deployment and retrieval. Work would be stopped if listed species are 

observed in the area to minimize entanglement risk.

• When using a boat or platform to conduct SCUBA operations, at least one person would maintain 

visual watch for protected species to ensure none are sighted within the working area. If a listed 

species moves into the work area, cessation of operation of any moving equipment within 15 m 

(50 ft) of the animal would occur and only resume when the species has left the project area. 

SCUBA divers involved in in-water activities would have proper training and be capable of 

responsible dive practices such that they minimize injury to organisms and avoid unnecessary 

habitat impacts.

Underwater activities would likely only displace sea turtles and prey within the immediate vicinity of 

vessels used by NOS or divers and would not cause any mortality or direct injury to sea turtles. Sea turtles 

and their prey are expected to return to project areas after the completion of NOS underwater activities 

and are not expected to experience any long-term changes in habitat availability, habitat use, or energy 

expenditure. As such, the impacts to sea turtles and sea turtle habitat, including designated critical 

habitat, from underwater activities would continue to be adverse, negligible to minor, and therefore

insignificant. 

3.6.2.2.6 Onshore Activities

NOS onshore projects would comprise installation, operation, and maintenance of shore-based GPS 

reference stations and installation and maintenance of tide gauges. The majority of sea turtle species 

move seasonally between foraging and nesting areas (Mansfield et al., 2009; Hawkes et al., 2011). Impacts 

from onshore projects could potentially occur if the site is located near a nesting beach, in which case it 

is likely that large numbers of sea turtles would be present both on the beach and within nearshore waters 

during the nesting season. Female sea turtles are particularly sensitive to human and other artificial 

disturbances (e.g., anthropogenic light sources) while selecting nest sites, and disturbance resulting from 

onshore projects could disrupt nesting behavior and decrease nest success. However, since female sea 

turtles come ashore and dig their nests at night, there is little likelihood of any NOS activities conducted 

onshore during daytime hours directly disturbing them. Sea turtles are long-lived organisms that have a 

very low likelihood of surviving to sexual maturity (Davenport, 1997), and decreased nest success would 

have long-term, adverse effects on the populations of all sea turtle species.

Low-flying aircraft, specifically helicopters, are infrequently used to access GPS reference stations and tide 

gauges in remote areas of the Alaska Region and could also disturb sea turtles through sound and visual 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

268

disturbance. Behavioral responses to low-flying aircraft are similar to those caused by vessel sound,

presence, and movement and include evasive diving or rapid changes in swimming speed and direction. 

The level of sea turtle disturbance caused by passing aircraft is contingent upon the aircraft’s altitude, the 

aspect (direction and angle) of the aircraft relative to the receiver, receiver depth and water depth, and 

seafloor type. However, any exposure of individual sea turtles to aircraft-related sound would be expected 

to cause only temporary disturbance or displacement from the project area. Furthermore, sea turtles only 

rarely occur within the Alaskan region, which substantially lowers the likelihood of their exposure to 

aircraft. 

Onshore activity would likely only displace sea turtles and prey within the immediate vicinity of the project 

area and would not cause any mortality or direct injury to sea turtles. Sea turtles and their prey are 

expected to return to project areas after the completion of NOS onshore activities and are not expected 

to experience any long-term changes in habitat availability, habitat use, or energy expenditure. Given the 

relatively low level of onshore project activity anticipated, along with the short duration of exposure to 

sound and visual disturbance, the impacts to sea turtles and sea turtle habitat, including critical habitat,

from NOS onshore activities would continue to be adverse, negligible, and therefore insignificant. 

3.6.2.2.7 Air Emissions

Smokestack and two-stroke outboard motor emissions from vessels used by NOS would release 

pollutants, including CO2, into the atmosphere of the project area and immediately surrounding areas. 

Higher atmospheric CO2 levels increase dissolved CO2 and bicarbonate ions in seawater, which 

subsequently leads to a decrease in seawater pH and carbonate ions. In general, a decrease in pH 

corresponds to a simultaneous increase in acidity, termed “ocean acidification.” Changes in seawater 

carbon chemistry may adversely affect marine biota through a variety of biochemical, physiological, and 

physical processes and interactions. Ocean acidification resulting from higher atmospheric CO2 levels due 

to anthropogenic emissions is within the range of sea turtle tolerance and is not expected to cause any 

direct harm to individuals and the population. Nonetheless, air emissions could potentially degrade sea 

turtle habitat indirectly, including designated critical habitat, by reducing the availability of 

macroinvertebrate prey species which are particularly sensitive to acidity during their larval life stages. 

It is important to note that vessels used by NOS make up only a small proportion of the total amount of 

vessel operation (Section 2.4.1) and would only marginally contribute to the overall level of emissions 

within the action area. However, any emissions of anthropogenic GHG (CO2, CH4, and N2O) by vessels used 

by NOS would contribute negligibly to ongoing changes in oceanic conditions (as well as atmospheric and 

terrestrial conditions) (Limpinsel et al., 2017). Thus, NOS projects would not substantially increase air 

emissions in the oceans and any increased sea turtle competition, foraging effort, or energy expenditure 

as a result of reduced prey availability from ocean acidification is not expected to substantially affect sea 

turtle individuals or populations. 

Air emissions or their resulting contribution to ocean acidification would not cause any mortality or direct 

injury to sea turtles. Sea turtle macroinvertebrate prey populations could potentially be affected by ocean 

acidification, but any changes in population size would be well within the natural range of variability. Sea 

turtles are not expected to experience any long-term changes in habitat availability, habitat use, or energy 

expenditure from air emissions as the amount of emissions from vessels used by NOS would be negligible 

when compared to emissions from all other vessel activity in the action area. Thus, impacts to sea turtles 

and sea turtle habitat, including critical habitat, from air emissions would continue to be adverse,

negligible to minor due to the ability of air emissions to travel beyond the immediate project area, and

therefore insignificant. 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

269

3.6.2.2.8 Conclusion

Although the effects of impact causing factors on sea turtles and their associated habitat range from 

negligible to moderate, moderate impacts are only expected in the very unlikely occurrence of an 

accidental spill of oil, fuel, or chemicals. Since all other impacts range from negligible to minor, the overall

impact of Alternative A on sea turtles and their habitat, including designated critical habitat, would 

continue to be adverse and minor; therefore, impacts of Alternative A would continue to be insignificant. 

3.6.2.3 Alternative B: Conduct Surveys and Mapping for Coastal and Marine Data 

Collection with Equipment Upgrades, Improved Hydroacoustic Devices, and 

New Tide Stations

Projects under Alternative B would take place in the same geographic areas and timeframes as under 

Alternative A; however, Alternative B would include more projects, activities, and nautical miles traveled 

than Alternative A. Under Alternative B, excluding survey effort in the Great Lakes which would not impact 

sea turtles. NOS survey effort would cover a total of 2,896,712 nm (5,364,710 km) across all five regions 

over the five-year period. Overall, survey effort would cover an additional 263,337 nm (487,701 km) under

Alternative B (see Table 3.5-14), a 10 percent increase over Alternative A (2,633,374 nm [4,877,009 km] 

total) across all regions over the five-year period. Thus, the greatest number of nautical miles surveyed 

each year would be in the Southeast Region (with approximately 47 percent of the survey effort); the level 

of effort in the other four regions would be at similar levels (approximately 10 percent of the survey effort 

in each region), and perhaps slightly greater in the Alaska Region where the survey effort would be 

somewhat higher overall (approximately 18 percent), but this area is only rarely visited by sea turtles. In 

general, it is expected that level of effort and overall impacts trend together (i.e., greater impacts where 

the survey effort is higher), but there are other factors, such as location and depth of surveys, hearing 

frequency of the animals, and population density of sea turtles, that add nuance to this trend.

Under Alternative B there would be crewed vessel operations covering 577,000 nm (1,070,000 km), as 

compared to 518,000 nm (959,000 km) under Alternative A. Vessel operations are among the most 

disruptive NOS activities to sea turtle populations and could contribute to impacts on sea turtles and sea 

turtle habitat through visual disturbance, direct collision, vessel sound, vessel wake and underwater 

turbulence, trailing equipment, accidental spills or waste disposal, and air emissions. Although the amount 

of crewed vessel operations would be greater under Alternative B than under Alternative A, the additional 

59,000 nm (109,000 km) would be distributed across the five regions of the EEZ. While these additional 

operations would result in greater impacts overall, the associated impact-causing factors would not be 

concentrated enough in any given area to substantially increase the magnitude of impact (e.g., from 

negligible to minor). This relationship is consistent for all other impact causing factors from proposed 

activities, such as onshore disturbance from the installation, maintenance, and removal of tide gauges 

and installation GPS reference stations; and entanglement risk from anchoring, bottom sample collection, 

and trailing video equipment.

Impacts of Alternative B on sea turtles and sea turtle habitat, including designated critical habitat, would 

be the same or slightly, but not appreciably, larger than those discussed above under Alternative A for 

each impact causing factor given that impacts do not scale proportionally with survey effort. Impacts to 

sea turtles resulting from Alternative A do not cause long-term changes in habitat use or behavior and 

would not substantially increase in intensity with the increased survey effort of Alternative B. Overall, 

impacts on sea turtles and their habitat, including designated critical habitat, would be adverse, minor, 

and therefore insignificant.
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

270

3.6.2.4 Alternative C: Upgrades and Improvements with Greater Funding Support

Projects under Alternative C would take place in the same geographic areas and timeframes as under 

Alternatives A and B; however, Alternative C would include more projects, activities, and nautical miles 

traveled, than Alternatives A and B. Under Alternative C, excluding survey effort in the Great Lakes which 

would not impact sea turtles, NOS survey effort would cover a total of 3,160,049 nm (5,852,411 km) across 

all five regions over the five-year period. Overall, NOS survey effort would cover an additional 263,337 nm 

(487,701 km) under Alternative C (see Table 3.5-21), an approximate nine percent increase over 

Alternative B (2,896,712 nm [5,364,710 km] total); and an additional 526,675 nm (975,402 km), an 

approximate 20 percent increase over Alternative A (2,633,374 nm [4,877,009 km] total) across all regions 

over the five-year period. Thus, the greatest number of nautical miles surveyed each year would be in the 

Southeast Region (with approximately 47 percent of the survey effort); the level of effort in the other four 

regions would be at similar levels (approximately 10 percent of the survey effort in each region), and

perhaps slightly greater in the Alaska Region where the survey effort would be somewhat higher overall 

(approximately 18 percent), but this area is only rarely visited by sea turtles. In general, it is expected that 

level of effort and overall impacts trend together (i.e., greater impacts where the survey effort is higher), 

but there are other factors, such as location and depth of surveys, hearing frequency of the animals, and 

population density of sea turtles, that add nuance to this trend.

Under Alternative C, crewed vessel operations would cover 637,000 nm (1,180,000 km), as compared to 

the 577,000 nm (1,070,000 km) under Alternative B and the 518,000 nm (959,000 km) under Alternative 

A. Vessel operations are among the most disruptive NOS activities to sea turtle populations and could 

contribute to impacts on sea turtles and their habitat through visual disturbance, direct collision, vessel 

sound, vessel wake and underwater turbulence, trailing equipment, accidental spills or waste disposal, 

and air emissions. Although the amount of crewed vessel operations would be greater under Alternative 

C than under Alternatives A and B, the additional 119,000 nm (220,388 km) as compared to Alternative A 

and the additional 60,000 nm (111,000 km) as compared to Alternative B would be distributed across the 

five regions of the EEZ. While these additional operations would result in greater impacts overall, the 

associated impact-causing factors would not be concentrated enough in any given area to substantially 

increase the magnitude of impact (e.g., from negligible to minor). This relationship is consistent for all 

other proposed activities contributing potential impacts, such as onshore disturbance from the 

installation, maintenance, and removal of tide gauges and installation GPS reference stations; and 

entanglement risk from anchoring, bottom sample collection, and trailing video equipment.

Impacts of Alternative C on sea turtles and sea turtle habitat, including designated critical habitat, would 

be the same or slightly, but not appreciably, larger than those discussed above under Alternative A for 

each impact causing factor. Impacts to sea turtles resulting from Alternative A do not cause long-term 

changes in habitat use or behavior and would not substantially increase in intensity with the increased 

survey effort of Alternative C. Overall, impacts on sea turtles and their habitat, including designated 

critical habitat, would be adverse, minor, and therefore insignificant.

3.6.2.5 Endangered Species Act Effects Determination

All species of sea turtles occurring within the action area are listed under the ESA, and federal agencies 

are required under the ESA to formally determine whether their actions may affect sea turtles or their 

designated critical habitat. Effects determinations divide potential effects into three categories: 

• No Effect; 

• May Affect, but Not Likely to Adversely Affect; and 

• May Affect, and is Likely to Adversely Affect. 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

271

Actions receiving a “No Effect” designation do not impact listed species or their designated critical habitat

(hereafter listed resources) either positively or negatively; this designation is typically only used in 

situations where no listed resources are present in the action area. Actions receiving a “May Affect, but 

Not Likely to Adversely Affect” designation have only beneficial, insignificant, or discountable effects to 

listed resources. Effects are considered insignificant if they are of low relative impact, undetectable, not 

measurable, or cannot be evaluated. Adverse effects are considered discountable if they are extremely 

unlikely to occur. Actions designated as “May Affect, and is Likely to Adversely Affect” will negatively 

impact any exposed listed resources. 

Sea turtles cannot hear the frequencies emitted by active underwater acoustic sources. Furthermore, due 

to the mobile and temporary nature of the projects, the small area of the sea floor affected during the 

projects relative to the entire EEZ, and the possibility of any individual sea turtles and their prey

temporarily moving away from sounds, the impacts of sound propagation from active underwater 

acoustic sources to sea turtles would be short term, limited to only a few individuals, and therefore

discountable (i.e., extremely unlikely to occur).

The proposed amount of vessel traffic associated with activities would be small in comparison to all the 

other non-project related vessel traffic in the EEZ. Disturbances from increased vessel traffic, including 

sound, presence and movement, water column disruption, and accidental waste discharge would be 

temporary to short-term and would likely only temporarily affect a few individual sea turtles. Additionally, 

mitigation measures for minimizing or avoiding impacts when one or more sea turtles are sighted while 

the vessel is underway are included in Appendix D. Because sound disturbance would be of temporary or 

of short duration and would occur infrequently in any given project area, the response by sea turtles to 

sound, wakes, and increased traffic from vessels used by NOS would be short term, limited to only a few 

individuals, and therefore discountable (i.e., extremely unlikely to occur).

The likelihood of an accidental spill is expected to be discountable (i.e., extremely unlikely to occur), and 

exposure of sea turtles and critical habitats to oil, fuel, and other contaminants is not expected. Such 

accidents may be caused by equipment malfunction, human error, or natural phenomena and are not 

expected during the course of NOS operations. In the unlikely event of an accidental spill, there would be 

very low likelihood for contaminants to make contact with the water because vessel operations personnel 

are required to respond immediately using established spill response procedures. Thus, effects from 

chemical contamination on sea turtles are discountable (i.e., extremely unlikely likely to occur).

Although underwater activities and equipment, such as ROVs, ADCPs, bottom samplers, drop cameras, 

and SCUBA divers could temporarily disturb and displace nearby sea turtles, effects would be temporary 

and negligible. Mitigation measuresthat would further minimize any disturbance are included in Appendix 

D. No large areas of seafloor disturbance by NOS underwater equipment and activities is planned or 

expected. Thus, the response to underwater equipment and activities by sea turtles would be short term, 

limited to only a few individuals, and therefore discountable (i.e., extremely unlikely to occur).

Onshore activities, such as aircraft use and the installation of onshore equipment, could potentially 

disturb and displace sea turtles from sensitive nesting areas, although if this occurs, it would be on a small 

scale and not widespread (e.g., limited to a few individuals). No substantial changes in sea turtle behavior 

or habitat use are expected in response to onshore activity; the response of sea turtles to onshore activity 

would be short term, limited to only a few individuals, and therefore discountable (i.e., extremely unlikely 

to occur). 
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

272

NOS concludes that the Proposed Action “May Affect, but Not Likely to Adversely Affect” all sea turtle 

species occurring in the action area, as listed in Table 3.6-3, except hawksbill turtles in the GAR. This 

species very rarely occurs within GAR and likely would not be encountered during any NOS projects or 

activities occurring under any of the action alternatives. As such, NOS concludes that the proposed project 

would have “No Effect” to hawksbill turtles within the GAR.

Since activities may occur in some areas within or adjacent to designated critical habitats, there is the 

potential for impacts on critical habitat that support sea turtles. Critical habitat may be minimally 

disturbed through short-term displacements or reductions of sea turtle prey and forage but would remain 

functional to maintain viability of dependent species. Due to the potential for effects that could range 

from negligible to minor as described in Sections 3.6.2.2-4, the Proposed Action “May Affect, but Not 

Likely to Adversely Affect” the designated critical habitat occurring in the action area (except for hawksbill 

turtles in the GAR as discussed above) as listed in Table 3.6-3.

Table 3.6-3. Summary of Effects Determinations for ESA-Listed Sea Turtles and Critical 

Habitat

ESA- Listed Sea Turtles, DPS

(if applicable) Species Determination Critical Habitat Determination

Loggerhead – Caretta caretta

Northwest Atlantic May Affect, but Not Likely to 

Adversely Affect

May Affect, but Not Likely to 

Adversely Affect

North Pacific May Affect, but Not Likely to 

Adversely Affect

N/A* (no critical habitat 

designated)

Green – Chelonia mydas

North Atlantic May Affect, but Not Likely to 

Adversely Affect

May Affect, but Not Likely to 

Adversely Affect

South Atlantic May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

Central North Pacific May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

Central West Pacific May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

Central South Pacific May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

East Pacific May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

Hawksbill – Eretmochelys imbricate

Hawksbill turtles within the SER, 

WCR, and PIR

May Affect, but Not Likely to 

Adversely Affect

May Affect, but Not Likely to 

Adversely Affect

Hawksbill turtles within the GAR No Effect No Effect
National Ocean Service Surveying and Mapping Projects in U.S. Waters for

Final Programmatic Environmental Impact Statement Coastal and Marine Data Acquisition

273

ESA- Listed Sea Turtles, DPS

(if applicable) Species Determination Critical Habitat Determination

Kemp’s Ridley – Lepidochelys kempii

-- May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

Olive Ridley – Lepidochelys olivacea

-- May Affect, but Not Likely to 

Adversely Affect

N/A (no critical habitat 

designated)

Leatherback – Dermochelys coriacea

-- May Affect, but Not Likely to 

Adversely Affect

May Affect, but Not Likely to 

Adversely Affect