Leatherback Sea Turtle- Michael Avila

Photo source: http://dinoanimals.com/animals/leatherback-sea-turtle-the-largest-turtle/

Leatherback Sea Turtle
Michael Avila

The Leatherback Sea Turtle (Dermochelys coriacea) is the largest and heaviest turtle alive in the modern world.  There are seven species of sea turtles, and the Leatherback Sea Turtle is the only marine turtle species without a hard shell.  Instead they have a thick leathery carapace that allows for better insulation when swimming in cold waters.  The Leatherback Sea Turtle was first listed as endangered in 1973 and has been endangered or threatened ever since (Alaska).

Description

Photo source: http://www.thesuperfins.com/do-turtles-eat-jellyfish/

Leatherback Sea Turtles are very large creatures; adults can reach 4 to 8 feet long, and have been recorded weighing up to 2000 pounds.  Its skin is primarily dark grey with the addition of white spots all over its body.  Once a female leatherback reaches sexual maturity at age 16, she will nest about 6 times within a single nesting season producing a yield of about 80 eggs per nest (Florida USFG).

The Leatherback Sea Turtle's diet typically consists of jellyfish, but also has been known to include seaweed, squid, crustaceans, fish, and sea urchins.  Their throats have adapted to have esophageal papillae, pictured to above, which grabs ahold of the jelly fish so it doesn't slip out while the turtle releases excess salt water from its mouth.  These 3-inch spines also protect against the jellyfish stings (Florida USFG).

Population and Geographic Range

Photo source: https://nature.nps.gov/biology/migratoryspecies/leatherbackturtle.cfm

The Leatherback Turtle has the largest global distribution of any reptile.  They can be found in moderate water temperatures and places such: the Atlantic, the Pacific, the Indian Oceans and the Mediterranean Sea.  Since their range is broad, some specimen have evolutionarily adapted by acquiring a thick, leathery-back, which replaced what was once a shell. This adaptation allows for them to be able to traverse water that is colder than tropical waters.  In the Atlantic, they can be found as far north as Norway and the Arctic Circle, on the other hand, some venture down to the southern tip of Africa.  Thus it has been determined that as a direct result of their wide range, the Leatherback's migration pattern is the longest of all sea turtles, and they spend almost half their lives at sea (see picture below).

Migration Pattern of the Leatherback Sea Turtle
Photo source: https://www.umces.edu/cbl/release/2012/feb/29/landmark-study-leatherback-turtle-migration-identifies-pacific-danger-zones-crit

The population of the Leatherback Sea Turtle is typically estimated by how many nesting sites are found in a single area which is then measured over many years.  The largest nesting population is in the western Atlantic department French Guiana, with nesting sites varying between 5,029 and 63,294 nests between 1967 and 2005.  No nesting occurs on beaches under United States jurisdiction currently, as the Leatherback Sea Turtle prefers nesting on black sand.  The estimated total population of Leatherback Sea Turtles was 115,000 individuals in 1980.  The population estimates have declined over the years, as recent estimates put their population at around 30,000 individuals.  The adult Leatherback Sea Turtle are highly migratory, therefore making them a challenge to study (ECOS). 

Main Threats

The Leatherback Sea Turtle is listed as endangered under the U.S. Endangered Species Act (ESA) of 1973 as a direct result of the severe declination in its worldwide population.  "Primary threats to the species are incidental take in coastal and high seas fisheries, and the killing of nesting females and collecting of eggs at the nesting beaches." (ECOS)  

https://franslanting.photoshelter.com/image/I0000ek.8apgTedg

One of the main threats to the Leatherback Sea Turtle occurs as a result of net fishing.  Leatherbacks are regularly caught in drifting fishing nets and active longline fishing lines.  These fishing methods have a long history of ensnaring and killing leatherback turtles in the Northern Pacific (ECOS).  Between 1935-1982, Leatherbacks were reported to be the most common species caught in fishing lines.  During most of that span, the populations were almost fourfold of what they are now.  As fishing effort increases, so does the reported amount of Leatherbacks caught in nets.  Another threat from fisheries is the ingestion of fishing debris, such as nets and other manmade objects, which has been found in the stomach of dead Leatherback Sea Turtles.  

A paper published in 1983 stated that almost all of the Leatherback eggs in Thailand were poached, and in some other regions the practice of harvesting eggs and illegal poaching has removed more than 95% of the eggs (WWF Global).  Humans negatively affect nesting beaches in three main ways: taking eggs from the nesting sites, increased human presence near nesting sites, and coastal construction near nesting sites.  Harvesting eggs from nesting sites is a constant widespread threat to the species population growth.  Increased recreational and commercial use of nesting beaches leads to loss of habitat for the turtles to nest on.  Finally, coastal property is valuable in the modern world, especially when it includes a stretch of sandy beach.  Construction occurs quickly and takes nesting beaches away from Leatherback Sea Turtles; this also can include walkways, roadways, hotels, homes, sea walls and jetties.

Recovery Plan

According to ECOS, Leatherback Sea Turtles in the Pacific Ocean should be given the highest priority when it comes to recovery actions.  The overall goal of the recovery plan is to remove the species from the U.S. Endangered Species Act (ESA).  

The U.S. Fish and Wildlife Recovery Plan has a 5 step process to achieve recovery; the steps are in the following list:

1) Eliminate incidental take of leatherbacks in U.S. and international commercial fisheries.
2) Support the efforts of Mexico and the countries of Central America to census and protect nesting leatherbacks, their eggs, and nesting beaches.
3) Determine movement patterns, habitat needs and primary foraging areas for the species throughout its range.
4) Determine population size and status in U.S. waters through regular aerial or on-water surveys.

5) Identify stock home ranges using DNA analysis. 

How can you help?

The average individual may have a difficult time making a direct impact in the Leatherback Sea Turtle's marine recovery, unless you are a fisherman or can convince a fisherman against using longline nets.  Instead the common person has to focus on how they can protect Leatherback Sea Turtles' nesting on land.

• Do not litter.  Litter on beaches can make it hard for the turtles to find a nesting site.
• Turn all lights off near beaches.  This can include car's headlights or home lights if you live near the beach. 
• Dispose of fishing materials properly.  Improper disposal of fishing materials can lead to tangling the Leatherback Sea Turtles fins.  This leads to permanent damage of their fins, or death. 
• Do not drive on the beach.  Cars scare the Leatherback Turtles from choosing their nesting sport or there could be nested eggs already on the beach that the car may run over and damage.
• Leave the beach better than you found it.  Leaving items behind on the beach, or having bonfires, can impair the turtles from finding proper nesting sites.

Sources:

Environmental Conservation Online System, U.S. Fish and Wildlife Recovery Plan of the Leatherback Turtle (ECOS), https://ecos.fws.gov/docs/recovery_plan/981201d.pdf

WWF Global (WWF Global), http://wwf.panda.org/what_we_do/endangered_species/marine_turtles/leatherback_turtle/

Alaska Department of Fish and Game (Alaska), http://www.adfg.alaska.gov/index.cfm?adfg=specialstatus.fedsummary&species=leatherbackseaturtle

U.S. Fish and Wildlife, Florida Office (Florida USFG), https://www.fws.gov/northflorida/seaturtles/turtle%20factsheets/leatherback-sea-turtle.htm