sea turtle migration-tracking & coastal habitat educators ......sea turtle survival league -...

4424 NW 13th Street, Suite A-1, Gainesville, Florida 32609(352) 373-6441 FAX (352) 375-2449

E-mail: [email protected] Web Page: http://www.cccturtle.org

Sea TurtleMigration-Tracking &

Coastal HabitatEducation Program

A program of Caribbean Conservation Corp.

An Educator's Guidewith information about sea turtle natural history, coastal

habitat ecology, high technology research and conservationefforts to protect sea turtles and their habitats.

Prepared by

Sea Turtle Survival League - Educator's Guide

Sea Turtles:The Five Species Found in U.S. Waters

Loggerheads lay eggs atintervals of 2, 3, or more years.Nesting season runs from Maythrough September in the U.S.They lay 4 to 7 nests per season,approximately 14 days apart.The average number of eggs ineach clutch ranges from 100 to126, and the eggs incubate forabout 60 days. Loggerheadnesting is concentrated in twomain areas of the world -- atMasirah Island, Oman, in themiddle east and on the coast ofthe southeastern United States.The Masirah Island's annualnesting population is about30,000 females, while up to25,000 loggerheads nest in thesoutheast U.S. each year. Themajority of nesting in thesoutheast U.S. takes place onFlorida's Atlantic coast betweenthe inlet at Cape Canaveraland Sebastian Inlet, especiallywithin the Archie Carr NationalWildlife Refuge.

Green turtle(Chelonia mydas)

Green turtles are an endan-gered species around the world,but they still nest in significantnumbers on the east coast ofFlorida. They are easily distin-guished from other sea turtlesbecause they have a single pairof scales in front of their eyesrather than two pairs as othersea turtles have. The greenturtle is the largest of theCheloniidae family. Female

green turtles that nest in Floridaaverage more than three feet incarapace length, and averageabout 300 pounds in weight.The largest green turtle everfound was 5 feet in length and871 pounds.

Green turtles nest at inter-

vals of 2, 3, or more years. Theylay an average of 3 to 5 eggclutches, with about 12 daysbetween each nesting. Thereare an average of 115 eggs perclutch and they incubate forabout 60 days. Nesting seasonruns from June through Octoberin the U.S. The largest nestingsite in the western hemisphere isat Tortuguero, Costa Rica.

Leatherback(Dermochelys coriacea)

Leatherbacks are alsoendangered, but a few nest onthe east coast of Florida eachyear. The leatherback is thechampion of sea turtles. Thisspecies grows the largest, divesthe deepest, and travels thefarthest of all sea turtles. Matureleath-erbacks typically reachabout 4 to 8 feet in length and

Loggerhead hatchling

ost scientists recognizeseven living species ofsea turtles, which are

grouped into six genera. Thefive species regularly found inU.S. waters are described below:

Loggerhead(Caretta caretta)

Of all the sea turtles thatnest in the United States, theloggerhead is the one seen mostoften. While all other speciesfound near the U.S. coastlineare listed as endangered, theloggerhead is classified asthreatened. This means logger-heads are more numerous thanthe other species, but they arestill in danger of extinction.

Adult loggerheads weigh up

to 350 pounds and have areddish-brown carapace (uppershell) and a dull brown toyellow plastron (lower shell).Fully grown, a loggerhead'scarapace is typically 32 to 41inches long (82-105cm).

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Green turtle nesting

Sea Turtle Survival League - Educator's Guide Page 9

weigh from 650 to 1,300pounds. The largest leatherbackever recorded was almost 10 feet(3 m) from the tip of its beak tothe tip of its tail and weighed inat 2,019 pounds (916 kg). Theleatherback is the only sea turtlethat lacks a hard shell. It isnamed for its large, elongatedshell which is composed of alayer of thin, tough, rubberyskin, strengthened by thousandsof tiny bone plates. Sevennarrow ridges run down thelength of the carapace, which istypically black with many whitespots. The lower shell is whitishto black and marked by 5 ridges.The body of a leatherback isbarrel shaped, tapering at therear to a blunt point. With thisstreamlined body shape and thepowerful front flippers, a leath-erback can swim thousands ofmiles over open ocean andagainst fast currents.

Leatherbacks feed almostexclusively on jellyfish. It isremarkable that this large,

active animal can survive on adiet of jellyfish, which arecomposed mostly of water andappear to be a poor source ofnutrients. Young leatherbacks

in captivity can eat twice theirweight in jellyfish each day.

Leatherbacks approachcoastal waters only duringbreeding season. Nesting occursthroughout the Caribbean, onthe northern coast of SouthAmerica, the Pacific coast ofCentral America, and on theeast coast of Florida. Nestingseason runs from Marchthrough July. Leatherbacks nestevery 2 to 3 years, laying 6 to 9egg clutches in a nesting season.Each clutch contains approxi-mately 80 fertilized eggs the sizeof billiard balls and 30 smaller,unfertilized eggs. There is anaverage of 10 days betweennestings. The eggs incubate forapproximately 65 days.

Hawksbill(Eretmochelys imbricata)

Hawksbills are endangeredin large part because people killthem to get their beautifulshells, which are used to makejewelry and other products.Although they are found in U.S.waters, they rarely nest in NorthAmerica.

The hawksbill is one of thesmaller sea turtles, measuring 30to 36 inches in carapace length(76-91 cm) and weighing 100 to150 pounds (40-60 kg).

Hawksbill turtles nest atintervals of 2, 3, or more years.An average of 2 to 4 eggclutches are laid approximately15 days apart during nestingseason. An average of 160 eggsper clutch are laid and theyincubate for approximately 60days. Although they nest onbeaches throughout the Carib-

Adult hawksbill

bean, they are no longer foundanywhere in large numbers.

Kemp’s ridley(Lepidochelys kempii)

Kemp’s ridleys are the mostendangered of all sea turtles;they are also the smallest.Adults measure 24 to 28 inches(62-70 cm) in carapace lengthand weigh between 77 and 100pounds (35-45 kg). The cara-pace of adults is olive green andthe plastron is yellowish.

Unlike other sea turtles,Kemp’s ridleys nest annually.They lay about 2 clutchesduring each season, about 25days apart. Each nest containsaround 105 eggs, which incu-bate 55 days. The only majorbreeding site of the Kemp’sridley is on a small strip of beachat Rancho Nuevo, Mexico.Kemp’s ridleys nest in masssynchronized nestings calledarribadas(Spanish for “arrival”).

The arribada of Kemp'sridleys occurs at regular intervalsbetween April and June. In1942, a Mexican architectfilmed an estimated 42,000ridleys nesting at RanchoNuevo in one day. During1995, only 1,429 ridley nestswere laid at Rancho Nuevo.

Leatherback hatchling

Sea Turtles:Behavior Patterns

ea turtles are generallysolitary creatures thatremain submerged for

much of the time they are at sea,which makes them extremelydifficult to study. They rarelyinteract with one anotheroutside of courtship and mating.Ridleys, however, do cometogether in massive groupsduring their arribadas. But evenwhen large numbers of turtlesgather on feeding grounds orduring migration, there is littlebehavioral exchange amongindividuals. Because of thedifficulty in studying marineturtles in the open ocean, thereare a great many things stillunknown about their behavior.Decades of research, however,including observations at sea,have produced useful insightsinto daily activities and behav-iors such as courtship, matingand nesting.

Daily ActivitiesSea turtles are known to feed

and rest off and on during atypical day. During the nestingseason, research conducted inthe southeast United States hasshown that loggerheads followregular patterns between thenesting beach and offshore reefsand other rocky structures. It ispresumed that mating and/orfeeding occur at these offshoreareas. Sea turtles may migrate

hundreds or even thousands ofmiles during their migations.

Sea turtles can sleep at thesurface while in deep water oron the bottom wedged underrocks in nearshore waters.Many divers have seen greenturtles sleeping under ledges inreefs and rocks. Hatchlingstypically sleep floating on thesurface, and they usually havetheir front flippers folded backover the top of their backs.

Courtship & MatingCourtship and mating for

most sea turtles is believed tooccur during a limited “recep-tive” period prior to the female'sfirst nesting emergence. After-wards, only females come ashoreto nest; males almost neverreturn to land once they leavethe sand of their natal beach.During mating season, malesmay court a female by nuzzlingher head or by gently biting theback of her neck and rear

flippers. If the female does notflee, the male attaches himself tothe back of the female's shell bygripping her top shell with clawsin his front flippers. He thenfolds his long tail under her shellto copulate. Females observedon the nesting beach afterrecently mating often havescratched shells and may bebleeding from where the maleswere hooked to their shells.

Copulation can take placeeither on the surface or under

water. Sometimes several maleswill compete for females andmay even fight each other.Observers of sea turtle matinghave reported very aggressivebehavior by both the males andfemales.

Females may mate withseveral males just prior to nest-ing season and store the spermfor several months. When shefinally lays her eggs, they willhave been fertilized by a varietyof males. This behavior mayhelp keep genetic diversity high


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in the population.

Nesting, Incubationand Emergence

Very little is known aboutwhy sea turtles nest on somebeaches and not on others. InFlorida, loggerheads nest by thethousands on the central eastcoast, while identical lookingbeaches to the north see farfewer loggerheads. This nestingdistribution may reflect condi-tions that existed centuries ago,when temperature, beachprofiles or the lack of predationmade some areas preferable tosea turtles.

Today, humans are affectingthe places where sea turtles nest.Beach erosion caused by coastalarmoring and navigationalinlets, artificial lighting andbeach renourishment are allimpacting once pristine beaches.These changes will likely havelasting effects on future nestingpatterns. The more we under-

stand about how, where andwhen sea turtles nest, the betterwe will be able to protect theirnesting habitat.

Beach Selection

Most females return faithfullyto the same beach each timethey are ready to nest. Not onlydo they appear on the samebeach, they often emerge withina few hundred yards of wherethey last nested.

Nesting Behavior

Only the females nest, and itoccurs most often at night. Thefemale crawls out of the ocean,pausing frequently as if carefullyscoping out her spot. Sometimesshe will crawl out of the ocean,but for unknown reasons decidenot to nest. This is a "falsecrawl," and it can happennaturally or be caused by artifi-cial lighting or the presence ofpeople on the beach.

Most females nest at leasttwice during the nesting season,

Step 1: Crawling to a suitable nesting site Step 2: Digging the body pit

although individuals of somespecies may nest only once andothers more than ten times. Seaturtles are generally slow andawkward on land, and nesting isexhausting work.

Constructing the Nest

The female turtle crawls to adry part of the beach and beginsto flings away loose sand withher flippers. She then constructsa "body pit" by digging with herflippers and rotating her body.After completing the body pit,she digs an egg cavity using hercupped rear flippers as shovels.The egg cavity is shaped roughlylike a tear drop and is usuallytilted slightly.

Laying and Burying the Eggs

When the turtle has finisheddigging the egg chamber, shebegins to lay eggs. Two or threeeggs drop out at a time, withmucus being secreted through-out egg-laying. The average sizeof a clutch ranges from about 80

Step 3: Digging the egg chamber

Eggs incubating in the nest. Hatchlings begin breaking out of shells. Hatchlings work their way to top of nest.

Page 12 Sea Turtle Survival League - Educator's Guide

Step 4: Laying the eggs

to 120 eggs, depending on thespecies. Because the eggs areflexible, they do not break asthey fall into the chamber. Thisflexibility also allows both thefemale and the nest to holdmore eggs.

Nesting sea turtles appear toshed tears, but the turtle is justsecreting salt that accumulatesin her body.

Many people believe thatwhile laying her eggs a seaturtles goes into a trance fromwhich she cannot be disturbed.This is not entirely true. A seaturtle is least likely to abandonnesting when she is laying hereggs, but some turtles will abortthe process if they are harassedor feel they are in danger. Forthis reason, it is important thatsea turtles are never disturbedduring nesting.

Once all the eggs are in thechamber, the mother turtle usesher rear flippers to push sandover the top of the egg cavity.Gradually, she packs the sanddown over the top. She then

begins using her front flippers torefill the body pit and disguisethe nest. By throwing sand inall directions, it is much harderfor predators to find the eggs.After the nest is thoroughlyconcealed, the female crawlsback to the sea to rest beforenesting again later that season orbefore beginning her migrationback to her feeding ground.Once a female has left her nest,she never returns to tend it.

Incubation

Incubation takes about 60days, but since the temperatureof the sand governs the speed atwhich the embryos develop, thehatching period can cover abroad range. Essentially, thehotter the sand surrounding thenest, the faster the embryos willdevelop. Cooler sand has atendency to produce moremales, with warmer sand pro-ducing a higher ratio of females.

Emerging from the Nest

Unlike baby alligators, which

Step 5: Burying and disguising the nest

Hatchlings erupt and head for water. Many animals eat hatchlings in the ocean. Hatchlings eat and drift in sargasso weed.

are liberated from their nest bytheir mother, sea turtlehatchlings must do it all them-selves. To break open theirshells, hatchlings use a sharp,temporary egg-tooth, called a"caruncle." The caruncle is anextension of the upper jaw thatfalls off soon after birth.

Digging out of the nest is agroup effort that can take severaldays. Hatchlings usually emergefrom their nest at night orduring a rainstorm when tem-peratures are cooler. Once theydecide to burst out, they eruptfrom the nest cavity as a group.The little turtles orient them-selves to the brightest horizon,and then dash toward the sea. Ifthey don't make it to the oceanquickly, many hatchlings willdie of dehydration in the sun orbe caught by predators like birdsand crabs.

Once in the water, theytypically swim several miles offshore, where they are caught incurrents and seaweed that maycarry them for years beforereturning to nearshore waters.

There are many obstacles forhatchlings in the open ocean.Sharks, big fish and circling birdsall eat baby turtles, and they dieafter accidentally eating tar ballsand plastic garbage. The ob-stacles are so numerous for babyturtles that only about one in1,000 survives to adulthood.


Sea Turtles:

Threats to their Survivalach year thousands ofhatchling turtlesemerge from their nests

along the southeastern coast ofthe United States and enter theAtlantic ocean. Sadly, only anestimated one in 1,000 to10,000 will survive to adult-hood. The natural obstaclesfaced by young and adult seaturtles are staggering, but it isthe increasing threats caused byhumans that are driving them toextinction. Today, all sea turtlesfound in U.S. waters are feder-ally listed as endangered, exceptfor the loggerhead, which islisted as threatened.

Natural ThreatsIn nature, sea turtles face a

host of life and death obstaclesto their survival. Predators suchas raccoons, crabs and ants raideggs and hatchlings still in thenest. Once they emerge,hatchlings make bite-sized meals

for birds, crabs and a host ofpredators in the ocean. Afterreaching adulthood, sea turtlesare relatively immune to preda-tion, except for the occasionalshark attack. These naturalthreats, however, are not thereasons sea turtle populationshave plummeted toward extinc-tion. To understand what reallythreatens sea turtle survival, wemust look at the actions ofhumans.

Human-Caused ThreatsIn many cultures around the

world, people still harvest seaturtle eggs for food. Mostcountries forbid the taking ofeggs, but enforcement is lax.Poaching is rampant, and theeggs can often be found for salein local markets. In these sameareas, adult sea turtles areharvested for their meat. Turtleproducts, such as jewelry madefrom hawksbill shells, also create

a direct threat to sea turtles.Lack of information about seaturtles leads many Americansto unwittingly support theinternational trade in theseendangered species. Buying andselling turtle products within theU.S. is strictly prohibited by law,but turtle shell jewelry andsouvenirs are the most frequentcontraband seized by customsofficials from tourists returningfrom the Caribbean.

Indirect threats are harder toquantify, but it is likely that theyare causing the greatest harm tosea turtle survival.

Commercial Fishing

The waters of the Gulf ofMexico and west Atlantic coastare a major habitat for turtles,but are also the main shrimpinggrounds in the U.S. Each year,thousands of turtles becomeentangled in fishing nets anddrown. Worldwide, shrimp

The killing of sea turtles for meat is still a significant problem in many Caribbean countries.


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nests. If renourishment isallowed to proceed duringnesting season, nests can also beburied far beneath the surface orrun over by heavy machinery.

Pollution

Pollution can have seriousimpacts on both sea turtles andthe food they eat. New researchsuggests that a disease nowkilling many sea turtles(fibropapillomas) may be linked

to pollution in the oceans andin nearshore waters. Whenpollution kills aquatic plant andanimal life, it also takes away thefood sea turtles eat. Oil spills,urban runoff of chemicals,including fertilizers and petro-leum, all contribute to waterpollution.

It may seem that the threatsto sea turtles are almost too bigto overcome, but they are not.Through personal actions, suchas making sure that oil, paintsand other toxic chemicals aredisposed of properly, reducingthe amount of fertilizer andchemicals used on lawns, partici-pating in plastic recyclingprograms and teaching othersabout what they can do help areall ways to make a difference.

trawling probably accounts forthe incidental death of morejuvenile and adult sea turtlesthan any other source. At onetime, as many as 55,000 seaturtles were killed each year inshrimp nets in the southeasternUnited States alone. Today, allU.S. shrimpers are required toput Turtle Excluder Devices(TEDs) in their trawl nets.Unfortunately, not all fishermencomply with the law, and seaturtles continue to drown inshrimp nets.

Ingestion of Debris and Plastic

Thousands of sea turtles diefrom eating or becoming en-tangled in nondegradable debriseach year, including packingbands, balloons, pellets, bottles,vinyl films, tar balls, andstyrofoam. Trash, particularlyplastic bags thrown overboardfrom boats or dumped nearbeaches and swept out to sea, iseaten by turtles and becomes adeadly meal. Leatherbacksespecially, cannot distinguishbetween floating jellyfish — amain component of their diet —and floating plastic bags.

Artificial Lighting

Nesting turtles once had notrouble finding a quiet, darkbeach on which to nest, butnow they must compete withtourists, businesses and coastalresidents for use of the beach.U.S. beaches are rapidly beinglined with seaside condomini-ums, houses and hotels. Lightsfrom these developments dis-courage females from nestingand cause hatchlings to becomedisoriented and wander inland,

where they often die of dehydra-tion or predation.

Coastal Armoring

Coastal armoring includesstructures such as sea walls, rockrevetments and sandbags thatare installed in an attempt toprotect beachfront property fromerosion. These structures oftenblock female turtles from reach-ing suitable nesting habitat andaccelerate erosion down the

beach. Armoring is especiallyproblematic along the east coastof Florida, where beach develop-ment is occurring in the veryplaces where sea turtles come tonest by the thousands.

Beach Nourishment

Beach nourishment consistsof pumping, trucking or other-wise depositing sand on a beachto replace what has been lost toerosion. While beach nourish-ment is often preferable toarmoring, it too can negativelyimpact sea turtles. If the sand istoo compacted for turtles to nestin or if the sand imported isdrastically different from nativebeach sediments, it can affectnest-site selection, diggingbehavior, incubation tempera-ture and the moisture content of

Leatherbacks feed on jellyfish, but can die by eating discarded plastic bags.


Sea Turtles:

Conservation Strategieso truly protect seaturtles around theworld, many different

countries and cultures mustcooperate and share responsibil-ity. International laws andagreements, research, and thework of dedicated organizationsand individuals each must play apart. Long-term protection ofsea turtles also means developingsolutions that reduce reliance onmanagement methods requiringdirect human involvement --such as moving nests or raisinghatchlings in captivity. If seaturtles cannot survive andreproduce on their own, withouthelp from humans, then they aredoomed.

Feeding and nesting groundsmust be protected, and a publicwildlife conservation ethic mustbe fostered that can withstandgaps in government regulations,pressure from private interests,and changes in the politicalclimate.

National Laws

Sea turtles are given legalprotection in the United Statesand its waters under the Endan-gered Species Act (ESA). TheESA lists the hawksbill, leather-back, Kemp’s ridley and greenturtle as endangered; and liststhe loggerhead as threatened.This designation makes it illegalto harm, harass or kill any seaturtles, hatchlings or their eggs.

It is also illegal to import, sell, ortransport turtles or their prod-ucts. In the United States, theNational Marine FisheriesService has jurisdiction over seaturtles in the water, while theU.S. Fish and Wildlife Service isresponsible for them on land.Other countries have their ownconservation laws and regula-tions that apply to sea turtles.

International Agreements

Some regulations affecting seaturtles are global in scope. The"Convention on InternationalTrade in Endangered Species"(CITES) controls internationaltrade in endangered and threat-ened species. Sea turtles arecovered under Appendix I ofthis agreement and receiveprotection from internationaltrade by all countries that havesigned the treaty.

State and Local Protection

In many states where seaturtles nest, state laws have beenpassed to protect the species.These laws meet or exceed therequirements of the ESA. InFlorida for instance, the MarineTurtle Protection Act waspassed giving state agencies thepower to enforce regulationsprotecting turtles and theirhabitat.

Some local governmentshave passed regulations toeliminate or control artificial

beachfront lighting, which isknown to deter females fromnesting and disorient hatchlings.

Conservation GoalsThe threats facing sea turtles

are numerous and, for the mostpart, humans are the problem.For those of us trying to protectsea turtles, it is a mixed blessingthat so many threats are human-caused. On one hand, it is veryhard to change human behav-ior. On the other hand, at leastthere is hope for eliminatingthreats. If sea turtles were goingextinct because of geological orclimatic changes, there would bevery little we could do to help.

Some immediate goals forprotecting sea turtles include:

* Crack down on illegalinternational trade in seaturtles and their products byenforcing laws and agree-ments.

* Decrease the turtle deathscaused by commercial fishingthrough enforcement ofTurtle Excluder Device(TED) and gill net regula-tions.

* Protect nesting beaches byestablishing parks and refugesor through regulationscombined with public educa-tion initiatives.

* Eliminate disturbances atnesting beaches by decreas-ing artificial lighting, halting


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beach armoring, regulatingbeach nourishment andlimiting the impacts of peopleon the beach.

* Enforce national and inter-national laws to minimize thedumping of pollutants andsolid waste into the oceanand nearshore waters.

* Continue research andmonitoring activities so thatthe population can bemonitored and conservationefforts can be focussed wherethey are most needed.

* Increase public awarenessand community participationin sea turtle conservationthrough educational pro-grams such as this one.

As sea turtles continue to be killed around the world by poachers on thenesting beach, in commercial fishing nets or by pollution, it is very difficultto explain the severe consequences this has on the species when thenumbers of nesting turtles seems to remain stable in areas. This visual aid,prepared by Dr. Jeanne Mortimer, is helpful in explaining how the completeharvesting of nesting females in a particular population (which is happeningnow in some parts of the world) may actually take decades to manifestitself on the nesting beach in reduced numbers of nesting adults. Whilethere may seem to be a never-ending supply of adult turtles to harvest, atsome point there will be no more maturing new generations of sea turtles toreplace those that have been killed. And once these too have been slaugh-tered, the population will crash suddenly.

In Florida and other stateswhere sea turtles nest, turtlewatches are conducted by trainedand permitted individuals. Thegoal is to educate people about seaturtles through direct contact,without disturbing the turtles. Ifyou are interested in going on aturtle walk, you can call SeaTurtle Survival League at (352)373-6441 for a list of guides nearyou. Sometimes people encountersea turtles on their own whilewalking on the beach at nightduring nesting season. If thishappens to you, here are somesimple rules to follow:

* Do not walk on the beach witha flashlight or shine a light inthe sea turtle's face. The lightmay cause the female to abort

the nesting process, or othersea turtles nearby may bediscouraged from nesting ifthere are lights on the beach.

* Do not take pictures usingflashes. This high-intensitylight can be even more disturb-ing than the flashlights.

* Stay clear and out of sight ofthe turtle until she beginslaying eggs, otherwise you mayscare her back into the sea.

* For your safety, stay away

from the turtle's head. Seaturtles, especially loggerheads,have very strong jaws and canharm you if provoked.

* Do not handle the eggs or putany foreign objects into thenest. You can introducebacteria or injure the eggs.

* Do not handle or ride the seaturtle. In addition to beingillegal, you may injure theturtle or cause her to leavewithout finishing nesting.

* Do not disturb tracks left byturtles. Researchers sometimesuse the tracks to identify thetype of turtles that nested andto find and mark the nests.

* Do enjoy the experience andremember it for the rest ofyour life.

What to Do If You Encounter a Nesting Sea Turtle


sea turtle migration-tracking & coastal habitat educators ......sea turtle survival league -...

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