Loggerhead Sea Turtle // Emily Holloway

Caretta carretta

The Loggerhead Turtle

By: Emily Holloway

Description and Ecology

Loggerhead turtles get their name from their exceptionally  large heads that contain powerful jaw muscles used to crush hard-shelled prey such as sea urchins and clams. They are the most common sea turtle species  in the Mediterranean and in U.S. waters, but can be found in numerous areas of the ocean around the world. Loggerheads are primarily carnivorous feeding mainly on shellfish that live on the bottom of the ocean. They eat clams, mussels, horseshoe crabs, and other invertebrates along with some fish and jellyfish. 

Their front flippers are short and thick with 2 claws and the rear flippers can have 2-3 claws.This sea turtle species is the largest of all hard-shelled turtles with a reddish-brown coloring on their heart-shaped carapace and dorsal scales of the head and fins. These scales are lined with light to medium yellow margins while their unscaled parts such as their neck are a dull brown. Hatchlings vary from light to dark brown to dark gray and lack the reddish-brown coloration until juvenile or adulthood. The Loggerhead turtle weighs between 175-400 lbs once fully grown with a length of 33-48 inches. They  live to be about 47-67 years old and reach sexual maturity within 17-33 years.

Loggerheads have a wide range encompassing all temperate and tropical regions, avoiding the most frigid waters of the world's oceans. They populate mainly in coastal habitats as well as along the continental shelves of the Atlantic, Pacific and Indian Oceans. 

The three basic ecosystems in which loggerheads live are the:

1. Terrestrial zone- the nesting beach where both egg laying, embryonic development, and hatching occur.
2. Neritic zone- the nearshore marine environment where water depths do not exceed 200m, generally including the continental shelf. This is where the hatchlings swim in a period of frenzied activity.
3. Oceanic zone- the vast open ocean environment where water depths are greater than 200m and turtles follow the surface and subsurface oceanic currents. 

Source: https://www.youtube.com/watch?v=eyzxrbhDAHg

Why Loggerhead Turtles Matter

Loggerhead turtles feed on hard-shelled prey recycling important nutrients and maintaining balanced ocean floor sediments in the process. This species carries populations of small plants and animals on their shells that comprise microhabitats. In fact, as many as 100 species of animals and plants have been recorded living on a single loggerhead turtle!

This is the global distribution of loggerhead nesting assemblages from https://ecos.fws.gov/docs/recovery_plan/090116.pdf

Defining the geographic range for the loggerhead turtle is highly difficult due to the migratory nature of the species. The species is commonly found throughout the North Atlantic including the Gulf of Mexico, northern Caribbean, the Bahamas, and eastward to West Africa, the western Mediterranean, and the west coast of Europe. The loggerhead species globally is comprised of 10 regional management units, or subpopulations, which break down the geographic population segments by looking at nesting sites, DNA studies, movements, and habitats throughout all life stages. The subpopulations are listed below and the total population size is unknown according to the ICUN Red List of Threatened Species. The most common measure for population abundance is the annual number of nests. A total of approximately 200,000 clutches-group of eggs laid by a turtle-are laid annually between all 10 subpopulations. With a range of 3-5.5 clutches annually per female, the total number of clutches can suggest that there are approximately 36,000-67,000 nesting females annually.

This is a map displaying the distribution of the 10 subpopulations for the loggerhead turtle
Source: http://www.iucnredlist.org/details/summary/3897/0

Listing Date

The Loggerhead was first listed as a threatened species throughout its range on July 28, 1978. The population is broken up into 10 population segments around the world with their own listing status or combined to create an entire species listing. 

Source: http://www.iucnredlist.org/details/3897/0

Type of Listing

While each population segment has their unique listing type, the areas that are the most endangered or are critically endangered are the North East Atlantic subpopulation, the West Indian Ocean subpopulation, and the South Pacific subpopulation.

Threats to the loggerhead population can be collected into quite an extensive list! This is primarily due to the fact that the species population can be harmed while living in or from destruction of one of their three ecosystems.

The Main Threats

• Resource Use (fisheries)
• Fisheries use an abundance of tactics to collect massive quantities of fish, often at the loggerheads caught and killed as bycatch. From gill net, shrimp and non-shrimp trawling, longline, pot/trap, and dredge fisheries, all are subject to entangle loggerheads. Shrimp trawling in the U.S. is one of the most detrimental threats to all sea turtle recovery. In a study in 1990 conducted by the National Academy of Sciences, between 5,000 to 50,000 loggerheads were killed annually by offshore shrimp catching in the southeast U.S. Atlantic and Gulf of Mexico.
• Resource Use (non-fisheries)



Source: https://goo.gl/images/pBKTaJ

• Loggerhead turtles have been harvested in waters for centuries as a source of protein and for other domestic uses. The ESA prohibits the harvest of loggerhead turtles in U.S. territorial waters, but this does not stop many other countries around the world from doing so. Illegal harvest also can occur.
• Offshore oil and fas production is associated with a number of threats to loggerhead turtles including oil spills, water quality from the operational discharge, seismic surveys, platform lighting, and noise from drillship and production activities. This can lead to capillary damage, debilitation, disorientation, loss of motor control, fatal injuries, or death.

• Habitat degradation during nesting stage
• Success during the nesting stage is critical to the survival of the loggerhead turtle, and it is being threatened by a number of factors that damage the nesting habitats on ocean beaches. Human interference through artificial lighting can confuse baby hatchlings or deter female turtles from coming to shore to lay their eggs. Humans with coastal construction,  recreational beach equipment, beach vehicular driving, etc. can destroy the nests and all of the eggs in it. 
• Beach erosion can stem from short-term events such as tropical storms or hurricanes or human accelerated eroding events can cause nests to be washed away, destroyed, or never uncovered. 

Source: https://goo.gl/images/YRf88Q

• Pollution
• Oil pollution is proven to be fatal to all life stages of loggerheads. Sea turtles are at substantial risk if they encounter an oil spill, petroleum, or large amounts of tar in the environment. This contact impacts respiration, diving patterns, energy metabolism, and blood chemistry.
• Other pollution includes chemical pollution that have come from human use of chemical pollutants that run off through sewage, noise pollution from shipping or military activities, and thermal pollution.
• Marine debris in oceans from human waste such as plastic bags, raw plastic pellets, styrofoam pieces, balloons, tar balls, hooks, etc. are all risks for loggerheads as they are often ingested and lead to death. 
• Predation
• Predation varies at each stage whether it is raccoons, humans, or foxes on land taking the eggs, or large sharks and killer whales eating the loggerhead in water. The magnitude of loggerhead mortality caused by sharks is unknown. 
• Climate Change
• With rising sea levels and ocean temperatures, the loggerhead range varies while their nesting habitats decline. The loggerhead migrates in warm waters, so with rising temperatures they are able to expand their range to waters unknown with predators unknown as well. Rising sea levels along with natural catastophes-also more likely with climate change-can destroy sandy beaches that turtles lay their eggs. With limited habitats to develop young, the species faces stunted population growth.
• Another aspect of climate change is ocean acidification and oxygen levels which impact ranges and changes algal, plankton, and fish abundance which are main prey for loggerheads.

To address the many threats to the loggerhead turtle, naturally, the recovery plan outlined by the National Marine Fisheries Service and the U.S. Fish and Wildlife Service is just as thorough. However, the main points addressed for recovery focus on the monitoring of population and habitat wellbeing, minimization of harmful threats, and action towards further protecting the species. Below is a list of the significant aspects of the recovery plan that will lead to better protection and population growth for the loggerhead turtle. 

• Determine demographic paramedics, refine population genetic structure, and monitor distribution, abundance, and trends
• Monitoring nesting abundance and trends by recovery unit
• Maintain and/or adopt standardized criteria for on-the-ground nesting surveys
• Monitor in-water population abundance and trends
• Determine and monitor female reproductive output by recovery unit
• Determine geographic distribution patterns of in-water populations
• Develop and maintain a comprehensive GIS database of distribution and abundance
• Determine migratory pathways for all life history stages
• Assess, monitor, and protect habitats
• Ensure beach sand placement projects are conducted to accommodate loggerhead needs and does not degrade or eliminate nesting habitat. This will minimize the effects of beach and dune sand placement projects on loggerheads
• Minimize degradation of nesting habitat from barriers to nesting
• Maintain and acquire nesting beaches and adjacent uplands to be held in public trust
• Minimize the effects of climate change on loggerhead habitats
• Describe effects of sea level rise on loggerhead nesting beaches
• Implement measures and develop agreements to reduce atmospheric greenhouse gasses
• Minimize effects of light pollution on hatchlings and nesting females
• Implement and enforce lighting ordinances on lands under local/state/federal govt jurisdiction
• Protect neritic and oceanic habitats used by loggerheads
• Assess human activities and their effects on habitat (effects of bottom trawl and dredge fisheries, eutrophication, water management, oil/gas production, channel dredging, etc)
• Assess human activities (oil and gas, marine debris, other pollutants)
• Prevent over utilization for commercial, scientific, or education purposes
• Work with nations to quantify and eliminate commercial and subsistence harvest
• Education local communities in foreign nations on the benefits of sea turtle ecotourism as an alternative to harvest
• Minimize take of wild turtles for captive display
• Assess and manage disease and predation
• Reduce nest predation
• Develop diagnostic health assessment protocols and establish baselines for wild populations
• Ensure adequacy of regulatory mechanisms
• Develop, implement and enforce regulations to ensure long-term protection of loggerheads and their habitats
• Minimize loggerhead bycatch in fisheries using a gear-based strategy
• Facilitate recovery through public awareness, education, and information transfer

Minimize beach lighting

   Baby loggerhead hatchlings use light and reflections from the moon to guide them to the ocean. With extra light from beach fires, flashlights, and other artificial lighting can confuse the babies and lead them astray, thus killing them. This lighting can also deter female turtles from going onto the beach and laying their eggs, so it is important during nesting season to minimize the artificial lighting and disturbances on potential nesting beaches.

Keep beaches clean and free of trash!

   Turtles can get tangled or even eat the plastic and other trash both on shore and in the water, so limit your waste and discard items such as fishing lines, hooks, plastic bags, etc. 

Be aware of nesting areas and steer clear of nesting and hatching turtles

  While it is tempting to watch or touch the cute turtles seen on the beach but this disturbs the nesting and hatching process. Be conscious of where nesting sites are so ensure that they are preserved. 

Reduce the amount of chemicals you use

   The chemicals you use on your lawn, or in your everyday life can run off into the sewage system then further into coastal waters. These chemicals can have harmful effects on plant and animal life. A solution would be to either limit the use of these damaging chemicals or to switch to biodegradable alternatives.

Volunteer!

   Volunteer to organize or participate in beach day clean ups, fundraisers that donate to loggerhead turtle conservation efforts, and spread the word to others on what they can do to lessen the loss of these beautiful creatures.

 

Video Source: https://www.youtube.com/watch?v=vHPeEhp_6UU

https://ecos.fws.gov/docs/recovery_plan/090116.pdf

https://ecos.fws.gov/ecp0/profile/speciesProfile?spcode=C00U#recovery

http://www.iucnredlist.org/details/3897/0

https://www.worldwildlife.org/species/loggerhead-turtle

https://conserveturtles.org/information-sea-turtles-loggerhead-sea-turtle/

https://defenders.org/sites/default/files/publications/five-things-you-can-do-to-save-sea-turtles.pdf