8/20/2019 Doug Fraser Turtles 4

1/1

A4 Sunday, March 29, 2015 | Cape Cod Times | capecodtimes.com

495

Mass.

Fla.

Texas

Cuba

GULF OFMEXICO

ATLANTICOCEAN

Gulf Loopcurrent

Eddy

Kemp’s ridleys have a long voyage to reach Cape

About 90 percent of Cape Cod’s stranded sea turtles are Kemp’s ridleys. How many are here and how

many strand depend on many factors, f rom the variable path of oceanic currents to wind direction

during the stranding months of November and December. One scenario posits that ridleys hatched in

June get caught up in currents and end up in Cape Cod Bay the following April or May.

Area enlarged below

Gulf Stream

Once they round Florida, juvenile turtles can

be caught up in the Gulf Stream. The turtles

arrive in New England waters in a week to a

month. They also may bail out along the way,

swimming west toward coastal waters.

Cape Cod

Turtles that arrive in Cape Cod Bay could have:

1. Drifted west with loops of warm water spun off

the Gulf Stream.2. Been pushed in from Stellwagen and areas

north by Northeast storms.

3. Been led in by the migratory route south along

the coast and couldn’t find their way out. Some

may be swimming to Cape Cod Bay as a food

stop along an annual migratory route.

The Sargasso Sea

Hatchling sea turtles of other species,

including ridleys, may find their way

to the large floating weed mats of

Sargasso Sea, which is due east of

southeastern coastline. They couldbe part of a group that is older and

may migrate to and from New England

waters one or more times in their

 juvenile years.

Gulf Loop

If the loop current extends north into the

Gulf of Mexico toward Louisiana, where

there are more ridleys, it can capture those

less than a year old that are not powerful

swimmers and sweep them through the

Strait of Florida into the Atlantic.

Many ridley hatchlings congregate

in open sea and in floating mats

of Sargassum weed off Louisiana,

where they find food and shelter.

Adults can be found here as well.

Majornesting siteRancho Nuevo,Mexico

Adults

migrate to

mating areas

Nesting on

beach

Lost years

(5-20 years)

Developmental

migration

(5-20 years)

Hatchlings

Life cycle of Kemp’s ridley

sea turtles

MEXICO

Tamaulipas

Minor nesting sitePadre Island, Texas

95 percent of nestingoccurs on three beachesin Tamaulipas, Mexico

Kemp's ridley range Ocean current

COLD-STUNNING

As cold-blooded animals, sea turtles cannot produce their own heat but absorb the heat needed to maintain body

functions from the surrounding water. This means they require less food to survive, but the chemical reactions

needed to keep body processes and organ functions slow as the temperature drops.

50ºTurtles stop eating. Undigested

food can rot in the intestines and

produce gases that cause the

77-86ºOptimal core body temperature. Cold-stunned

turtles have internal temperatures as low as

33 degrees and heart and respiration rates

44-41ºTurtles die within 24 hours

when water temperatures

fall this low

Kidneys and liver stop

filtering blood properly

Core body

temperature

lowers

Nearly empty

digestive tractOrgans shut down

Cloaca prolapse

WHAT HAPPENS Immune system is suppressed as their metabolismslows, making them vulnerable to infections

and diseases. Most turtles have pneumonia,

which may, in part, occur because in their

immobilized state they have trouble breathing

without also ingesting water.

Muscles weaken

Turtles may be injured as

they wash up on shore, 

swallowing sand and

having it driven into

their eyes and other

openings, as well as

receiving abrasions to

their limbs and shell

from hitting rocks and

being dragged over the

sand by wave action.

Sea turtles float on the surface 

because their low metabolic

rate also leaves them unable

to swim, dive and surface,which is necessary to breathe.

STORY BY DOUG FRASER, CAPE COD TIMES • GRAPHIC BY FRED MATAMOROS, GATEHOUSE MEDIA

CAPE COD STRANDINGS

Cape Cod's unique hook shape confuses many animals as they attempt

to find a way out to deeper water and run into land on three sides.

Where sea turtles strand is controlled by wind direction. Turtles are

generally floating on the surface and are pushed shoreward by an

onshore wind. If the wind is offshore they die at sea.

79in the

1990s

20in the

1980s

95in the

2000s

193in 2010

and 2011

400in 2012

Over Over

1,200in 2014

87Barnstable

15Provincetown

1Yarmouth Port

287Wellfleet

99Brewster

14Bourne

1Chatham

1Nantucket

2Falmouth

1Martha’s Vineyard

Average number of Cape Cod cold-stunned turtles per year.

'

40Dennis

4Sandwich

 317Eastham

297Truro

61Orleans

 3Hull

Number ofstranded turtles

6

28

 3 10 miles

in the Atlantic and Gulf of Mexico. Even inridley hotspots such as the northern Gulfof Mexico, where an extensive search wasconducted for fouled turtles following theDeep Horizon oil spill, fewer than 1,000 werefound.

It caused many to question whether some-thing else might be in play. Was the numberof sea turtles in Cape waters far greater thanpreviously believed? Was a warming oceanencouraging them to linger longer, jeopardiz-ing their escape in the fall? Or was this yearsimply the perfect combination of windsand water temperature, trapping a higherpercentage than normal and pushing immo- bilized victims to shore and not out to sea?

Good questions, said Kathleen Hunt, asenior scientist at New England Aquarium inBoston.

“There is almost no research done on it atall,” Hunt said of turtle population estimatesand their life history in New England. MostKemp’s ridley research focuses on the epicen-ter of that population in the Gulf of Mexico. With more than 4.5 million hatchlingsreleased into the Gulf of Mexico since 1978,the fate of the Cape contingent is believed, bysome, to be inconsequential to the fate of theoverall population.

“Some scientists think that, in general, rid-

leys that get into the Atlantic and are takennorth beyond Virginia are lost to the popula-tion,” Putman said.

But there may be more of a push to study what’s happening in the Atlantic now thatKemp’s ridleys, once thought to be readyto take a major step back from the brink ofextinction, seem to be in a tailspin.

 All sea turtle species, including the fourthat visit Massachusetts — the Kemp’sridley, loggerhead, green and leatherbackturtles — are listed as endangered under theEndangered Species Act. As coastal species,their life cycle intersects with humans attoo many critical points: on beaches, whereshoreline development affects nesting sites,and in the water, where boating, fishing, pol-lution and climate change all can harm seaturtles.

The life history of Kemp’s ridley turtles in

particular makes them a prime candidate forextinction, with more than 95 percent bornalong an 18-mile stretch of beaches on Mex-ico’s Yucatan peninsula. A film taken in 1947showed more than 40,000 female ridleysnesting on one beach in Tamaulipas. Localsharvested many of the eggs and by the 1980s,there were fewer than 300 nesting femalesand just 800 nests on Mexican beaches.

But Mexico, with help from the U.S., pro-tected those nesting areas decades ago andstarted a nesting program in Texas. Along with cooperative efforts from the fishingindustry to reduce mortality from fishinggear, Kemp’s have seen a remarkable come- back. By 2009, there were more than 20,000nests and 8,000 nesting females. With anearly 20 percent annual growth rate in the

population, scientists predicted that by 2011,ridleys would move from endangered tothreatened, at risk of becoming endangered.

Cape Cod Bay: A false paradiseJust after the 2009 nesting season,

however, the number of Kemp’s ridley seaturtle nests made each year started droppingmysteriously. On Nov. 18, the same day bignumbers of ridleys were being rescued onthe Cape, participants at this year’s annualInternational Kemp’s Ridley Sea TurtleSymposium in Brownsville, Texas, were being told of an estimated 45 percent drop innesting females from 2009 to 2014.

Some scientists suggested food produc-tion in the Gulf of Mexico had declined andfemale ridleys were eating less and there-fore nesting less frequently, or that shrimptrawlers were catching and killing them ingreater numbers than previously thought, but the majority of symposium presentationsfocused on the impact of the massive DeepHorizon oil spill in April 2010 that occurredin areas where ridleys congregate.

“I don’t think we are pushing the extinc-tion panic button, but there certainly isconcern when an animal goes from exponen-tial increase to a decrease or leveling off,” saidErin Seney, a marine and fisheries ecologist with the Florida Fish and Game Conserva-tion Commission.

It’s hard to know the role that NewEngland turtles play without an idea of howmany are actually here and their behavior when they are here.

There are competing theories on whytropical turtles are found in New England.One premise says they come here deliber-ately, migrating north as do other species, insearch of food, from the Sargasso Sea and offthe Southern Atlantic coastline.

Putman’s ridley studies on juvenile migra-tion show that the number that do get herecan vary significantly from year to year. Hiscomputer models reveal that the numberof juvenile ridleys entering the Atlantic inany given year from the Gulf of Mexico vary widely and are dependent on the direction ofthe Gulf Loop Current.

“Most turtles getting pulled into the Atlantic are 1 to 2 years old,” said Putman,

and either may not be able to swim out of astrong current or are happy to remain withthe seaweed and food moving with it. Like

the jet stream, the Gulf Loop meandersand can remain south in the Gulf of Mexico before passing into the Atlantic through thenarrow strait between Cuba and Florida orloop north entering the sargassum weedmats of Kemp’s ridley territory and carryingoff juveniles living there. After they are sweptaround the Florida Keys, turtles get into the

Gulf Stream for a quick trip north.Most of the ridleys that washed up onCape beaches this fall likely hatched on beaches in Mexico or Texas in June, werecaught up in these powerful oceanic riversand reached New England by the next Aprilor May, Putman said.

Ridleys either enter Cape Cod Bay delib-erately or blunder into it, and it is a falseparadise of warm water and plentiful food.Fall descends quickly and unpredictably andit is not easy finding the way out of the Cape’sunusual hook-shaped shoreline. How manyescape is another unknown.

A chance to surviveFor those turtles that found their way into

Cape Cod Bay last summer, it was blissfully warm through October, with air tempera-

tures as high as 81 degrees. But change wascoming.

The shortened days meant less solar heat-ing of ocean waters. By Halloween, CapeCod Bay’s surface temperature was 55 to60 degrees, with rapidly expanding pools ofcold, 50-degree water.

By mid-November, whatever chance theturtles still remaining in Cape Cod Bay hadof getting south was gone because the ther-mal door had slammed shut. Along the coast,65-degree water had retreated south to LongIsland. Cape Cod Bay was locked in by animpassable barrier of cold water in the low50s for hundreds of miles in any direction.

Death was certain, because when youare a cold-blooded reptile, heat, or the lackof it, is the cruel master of your fate. Withthe exception of the massive jellyfish-eating

leatherbacks that use a heat-exchangemechanism to regulate their body tempera-ture, sea turtles’ body temperature matchestheir environment and the chemical reac-tions underlying basic body functions slow,then fail, as temperatures drop and heart rateand respiration slow and organs shut down.

 Although they can remain active at tem-peratures between 55 and 65 degrees, seaturtles stop eating once water temperaturesdrop to 50. They bob to the surface, possibly because their metabolism has slowed to thepoint where undigested food is producinggas that makes them buoyant or becausethey need to breathe and no longer have theenergy to swim. A black algae that grows nat-urally on their shell takes over once they areimmobilized, and their normal gray, white

and green color is covered in a mat of blackfuzz. With their immune system shut down,opportunistic diseases such as pneumonia

STRUGGLE TO SURVIVE T

TURTLESFrom Page A3