Hatchery - Costa Rica

From Day 1 in Costa Rica, and likely until the end of the season, hatchery work has been a focus of our Field Biologist team. Since the end of last season, roots and weeds have infiltrated the sand within the enclosed area. This is problematic for young hatchlings as they may get entangled in the fibrous roots and never reach the surface. In order to prevent such a tragedy, our team pulled weeds and dug trenches in the sand to remove the hazardous plants. After several weeks of blistered hands and sore bodies, we had dug one meter deep throughout the hatchery. This process of digging and turning over the sand has also helped to aerate it. Once the sand was prepared, square 1x1 meter plots were marked off in a grid. Separated by a center aisle, one side is reserved solely for relocated nests while the other is punctuated with experimental plots that are testing the effects of shading on sand temperatures. Improvements to the fence are an ongoing endeavor which is aided by Jesús Suárez, our station handy-man. These efforts are being made to dissuade pesky raccoons from entering our hatchery. Until their access is completely restricted, additional fortifications are needed for each relocated nest. We have developed a strategy of covering the nests with a wire mesh, similar to chicken wire, and held in place by short rebar stakes which line the outsides of each plot. Thus far, it has successfully prevented raccoons from getting the eggs within our hatchery. 

A nest will get relocated to the hatchery if it has an increased risk of predation or was laid below the high tide mark and risks being inundated with rising tidal waters. Our hatchery is filling up fast with Olive Ridley nests which are all being relocated due to the shallowness of their nest and subsequent risk of predation. We also have several Leatherback nests and a couple of Green Sea Turtle nests in the hatchery.

Each of the biologists on our team has been tasked with specific duties to perform throughout the season. We have team members who are responsible for collecting nest temperature data, in-situ nest triangulations, managing our research equipment, and managing the hatchery operations. My position is Hatchery Manager. I am responsible for making sure that nest relocation and hatchling emergence data are completely recorded for each nest in the field notebook and then entered on the data computer. Much of the data collection work is accomplished at night by the team of biologists and volunteers who are patrolling the beach when turtles are most active in carrying out their nesting behavior.

Nest Predation - Costa Rica

Raccoon Predation

For millions of years, mother sea turtles have been visiting the terrestrial environment just to lay their eggs. Usually arriving near high tide, most likely in order to reduce the distance traveled on the beach, a female turtle drags herself onto land and finds a suitable place to make her nest. Sometimes such a place is not found and the turtle simply turns around and leaves, this is called a false crawl, or she goes ahead and digs a nest anyway. A turtle may undertake this arduous task multiple times within the same nesting season. Each species undergoes these nesting activities in their own way. Leatherbacks dig deep nests for their eggs and then make several large body pits by disturbing nearby areas in order to conceal the true location of the nest. Olive Ridleys are quicker and dig shallow nests. After laying her eggs, an Olive Ridley will cover the nest by packing sand down on top of it. Alternating her rear flippers in a sort of stomping motion, she rocks side to side and performs what we fondly call the “Ridley Shuffle.” Average nest depth, clutch size, egg size, incubation period, and nest attempts vary widely from species to species. However, they all share some fundamental characteristics. They all must come on land to nest and parental care is non-existent. This life-history strategy has its pros and cons. It allows for more energetic investment in additional offspring, rather than expending that energy in raising young. Millions of eggs are produced with the safe bet that some will survive into adulthood, yet many do not last that long. Many do not even get a taste of the ocean waters.

One of the major quandaries facing sea turtle populations is nest predation. Shallow nests are breached by dogs, raccoons, coatis, crabs and even ants shortly after being laid. Hungry for the nutritious yolk, these animals devour turtle eggs and leave remaining eggs exposed and susceptible to infection. If given sufficient time to incubate, emerging hatchlings are then vulnerable to further predation by those same creatures which now include predatory birds. If they manage to avoid predators as they cross the beach and are not disoriented by human caused light pollution, arrival at the sea introduces a host of new and threatening dangers. This is why turtles invest so much energy into producing as many offspring as possible. The trade-off is that they are unable to care for their young. That is where biologists and conservationists like myself come in. In a form of altruistic behavior, we sacrifice our time and strength for the unrecompensed benefit of sea turtles. Here at Playa Grande we have a turtle hatchery, where nests that have a higher risk of predation or being drowned by rising tidal waters can be relocated. We have developed a system to protect these relocated nests by deterring unwelcome predators. In the hatchery, and under our watchful eyes, turtle eggs are in a safer location and can grow up unmolested by predatory critters. Our work in the hatchery helps minimize the loss of nests by predation and augments the number of hatchlings that enter the ocean.

Predated Nest

Dog Predation

Playa Ventanas - Costa Rica

Last night was the first official patrol on Playa Ventanas. Due to the timing of the ocean tides and our growing staff of biologists (now up to 7), we were able to have 3 teams patrolling the entire beach from 11 PM until 5 AM. Fortunately, I was scheduled to walk Playa Ventanas on its inaugural patrol. On our very first sweep of the beach we came across 2 nesting Olive Ridley Sea Turtles (Lepidochelys olivacea). We collected data from the turtles and then needed to relocate both clutches of eggs due to high risks of predation and tidal inundation. On our trek to the hatchery with bags full of turtle eggs, we were pleasantly surprised to find a bale of hatchlings crawling their way to the sea. We stopped for a while to ensure that all of the hatchlings successfully arrived in the water and began their journey out to sea. As we neared the hatchery, we discovered another sea turtle laying her eggs. That clutch also needed to be relocated and we had the team from North beach arrive to assist in the relocation process. Once the nests were safely buried in the hatchery, we returned to our patrolling activities along Playa Ventanas. The excitement was over, yet we had 3 more hours to patrol the beach. (I will explain patrol activities in greater detail on future posts and I apologize for not having photos of turtles/hatchlings. Due to our permits and regulations within the national park, we are not allowed to take photographs at night.) This night was a little busier than usual, but it had the added bonus of witnessing hatchlings emerge. Finishing as the sun came up, we returned to the station, cleaned up our sandy-selves, and caught up on some much-needed sleep.

Playa Ventanas