Leatherback Turtle, Trent Larson
ESA Assignment:
Dermochelys coriacea (Leatherback Turtle)
by Trent Larson
Source: https://www.miamidiscounttours.com/product_images/uploaded_images/leath
Description and Ecology
The leatherback turtle is the largest turtle among the seven other sea turtle species. They are also capable
of diving the deepest and traveling the furthest compared to the rest of the sea turtles.
The size of these species ranges from four to eight feet, and can weigh between 500-2000 pounds.
It’s shell is actually a mosaic of small bones that are layered by a tough, rubbery skin, making it the
only sea turtle species without a hard shell. They have high thermal tolerances, and have been observed
as north as Alaska and as south as Chile and New Zealand; this may be due to their large body mass
along with other features. Nesting occurs between March and July. When females reach the sexually
mature age of 16, they can nest five to seven times per nesting season. The staple of their diet consists
of jellyfish, but are also known for eating sea urchins, squid, crustaceans, fish, and floating seaweed.
In terms of habitat, they are the most pelagic (open ocean dwelling) sea turtle. Though during nesting
season, sandy nesting beaches backed with vegetation and sloped sufficiently so the distance to dry
sand is limited (FWS). Ecologically, these turtles play a critical role in the jellyfish populations
around the world. The decline in leatherback turtles have a trophic cascade effect, increasing jellyfish
populations and therefore decreasing fish populations. Leatherback turtles also play a significant role
in nutrient cycling between the oceans and beaches.
of diving the deepest and traveling the furthest compared to the rest of the sea turtles.
The size of these species ranges from four to eight feet, and can weigh between 500-2000 pounds.
It’s shell is actually a mosaic of small bones that are layered by a tough, rubbery skin, making it the
only sea turtle species without a hard shell. They have high thermal tolerances, and have been observed
as north as Alaska and as south as Chile and New Zealand; this may be due to their large body mass
along with other features. Nesting occurs between March and July. When females reach the sexually
mature age of 16, they can nest five to seven times per nesting season. The staple of their diet consists
of jellyfish, but are also known for eating sea urchins, squid, crustaceans, fish, and floating seaweed.
In terms of habitat, they are the most pelagic (open ocean dwelling) sea turtle. Though during nesting
season, sandy nesting beaches backed with vegetation and sloped sufficiently so the distance to dry
sand is limited (FWS). Ecologically, these turtles play a critical role in the jellyfish populations
around the world. The decline in leatherback turtles have a trophic cascade effect, increasing jellyfish
populations and therefore decreasing fish populations. Leatherback turtles also play a significant role
in nutrient cycling between the oceans and beaches.
Geographic and Population Changes
The leatherback turtle is distributed worldwide in temperate and tropical waters of the Atlantic,
Indian, and Pacific Oceans. Their physiological characteristics allow them to travel the most
extensive migration of any reptile. Their migration patterns are thousands of miles long, allowing
most to spend nearly half of their lives at sea. This picture below illustrates just how
Indian, and Pacific Oceans. Their physiological characteristics allow them to travel the most
extensive migration of any reptile. Their migration patterns are thousands of miles long, allowing
most to spend nearly half of their lives at sea. This picture below illustrates just how
Source:https://conserveturtles.org/stc-programs-research-partnerships/
much distance a leatherback sea turtle can travel for a migration. A majority of their
distribution is focused along the Pacific Ocean border. This is largely due to the fact that the coast
of Mexico is regarded as the most important leatherback breeding ground in the world. However,
studies have noticed a significant decline in leatherback turtle populations in Mexico within the decade
of 1985-1995. The nesting grounds used to carry 65 percent of the leatherback turtle’s population in
1980, and is now one percent of the estimated size. This trend in Mexico also reflects ongoing patterns
with leatherback turtle populations around the world. There were around 115,000 reproducing females
in 1980, with an estimated 34,000-36,000 existing worldwide today (Vanaqua).
of Mexico is regarded as the most important leatherback breeding ground in the world. However,
studies have noticed a significant decline in leatherback turtle populations in Mexico within the decade
of 1985-1995. The nesting grounds used to carry 65 percent of the leatherback turtle’s population in
1980, and is now one percent of the estimated size. This trend in Mexico also reflects ongoing patterns
with leatherback turtle populations around the world. There were around 115,000 reproducing females
in 1980, with an estimated 34,000-36,000 existing worldwide today (Vanaqua).
Causes/Main Threats
The Leatherback Sea Turtle was 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. The two most
The Leatherback Sea Turtle was 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. The two most
impactful threats to leatherback are the incidental take of them as bycatch, and the poaching of
them for their eggs and meat. For example, a paper published in 1983 stated that almost
100% of leatherback eggs in Thailand were poached, while in some areas the egg harvest
and illegal poaching has removed more than 95% of the clutches (WWF). The persistent collection of eggs will result in guaranteed reduced recruitment, leading to an eventual population decline. The collection of reproducing females is also detrimental on the leatherback population. Fisheries also stand as a significant threat to the leatherbacks, since they often fish along migratory patterns of adults off the Pacific. According to a study, Fishermen "regularly" catch leatherbacks in drift/gill nets off Monterey Bay, central California (ECOS). Other threats that are worth noting are:
- habitat degradation/destruction
- climate change
- pollution
- other human disturbances.
Recovery Plan
The recovery plan for leatherback turtles was published by the Pacific Sea Turtle Recovery
Team for the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Fish
and Wildlife Service. The plan itself is focused on the populations of leatherbacks among
the Pacific U.S.. They placed seven specific objectives that must be met in order for the
leatherback turtle to be delisted as endangered, noted below:
Team for the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Fish
and Wildlife Service. The plan itself is focused on the populations of leatherbacks among
the Pacific U.S.. They placed seven specific objectives that must be met in order for the
leatherback turtle to be delisted as endangered, noted below:
1) All regional stocks that use U.S. waters have been identified to source beaches based on
reasonable geographic parameters.
reasonable geographic parameters.
2) Each stock must average 5,000 (or a biologically reasonable estimate based on the goal
of maintaining a stable population in perpetuity) FENA over six years.
of maintaining a stable population in perpetuity) FENA over six years.
3) Nesting populations at "source beaches" are either stable or increasing over a 25 year
monitoring period.
monitoring period.
4) Existing foraging areas are maintained as healthy environments.
5) Foraging populations are exhibiting statistically significant increases at several key
foraging grounds within each stock region.
foraging grounds within each stock region.
6) All Priority #1 tasks have been implemented.
7) A management plan designed to maintain sustained populations of turtles is in place.
The overall goal of this recovery plan is to delist the leatherback turtle as endangered.
What Can You Do?
There are actually many things you can do to make a positive impact on the survival of the leatherback
turtle. There are a few simple things you can do to mitigate your impact and lessen the chance of
harming sea turtles. Here are a few examples:
Turn off any visible lights from the beach: This will lessen the chances of leatherback hatchlings
mistaking the reflections of the moon on the water for urban lighting.
Reduce your garbage production at home and on the beach: Practicing this easy step could prevent
the sea turtles from eating plastic that could be mistaken for jellyfish. Dispose of fishing materials
and chemicals properly.
Be aware of sea turtle hatchling sights: Being conscious of the hatchlings and leaving them
completely undisturbed with improve their mortality and relieve stress from the hatchlings.
References and Resources
Nice blog! I liked all the photos you used, they were informative. The actions you listed that we can do are very interesting and I wouldn't have thought of them. I found it super interesting that the Leatherback Turtle's shell is made of small bones.
ReplyDelete- Gina Harris
I had no idea about that this species is the largest and dives the deepest! I found your section about their ecology interesting. I also did a blog on turtles and was curious to find that both turtles suffer from the same threats and call for the same actions from everyday people.
ReplyDelete-Emily Holloway
I liked the photos used, and the maps of migration movement and the loggerhead turtle range were nice visuals and easy to follow. I knew that by-catch was a problem, but I did not know that was poaching for their eggs and meat which was interesting.
ReplyDelete-Julia Galvan
This turtle is so interesting. You had great photo choice in your blog, it made it very interactive and clear. It's sad to see all of these turtles are all experiencing similar threats.
ReplyDelete-Cierra Heiland
I like the use of the graph that shows their migration patterns. It helps to show that the issue is literally worldwide and that we can effect and animal halfway across the globe.
ReplyDelete-Dean Harris
It's crazy to hear how big these turtles can get and how far they travel during migration. It's too bad hearing about how drastically their populations have decreased. -Benjamin Holland
ReplyDeleteI really like your layout, because it made the information easy to follow and read. I never knew that there was a turtle without a hard shell and the fact that their eggs are poached is very unfortunate.-Ainsley Henderson
ReplyDeleteLoved reading about this turtle, they're so cool! I think the information about not having a traditional hard shell and instead a layer of thick skin over bones was really interesting. The maps were really helpful too. -Erin Ichimura
ReplyDeleteYour article has such a great flow! So interesting to hear the stats that the numbers of this turtle dropped from 115,000 reproducing females in 1980 to 34,000-36,000 today.
ReplyDelete-Elisabeth Huetter