Nava, M.

Sea Turtle Conservation Bonaire (STCB) has been protecting sea turtles on Bonaire since 1991, so this year represents the 26th Anniversary of our organization. In 2002, we standardized our research and monitoring efforts, following the appointment of a Scientific Officer. Annually we monitor our nesting beaches around Bonaire, conduct intensive in-water netting and snorkel surveys, and we regularly track sub-adult and post-breeding migrations using satellite telemetry. These techniques provide us with a better understanding of Bonaire sea turtles’ breeding success, abundance, health, growth rates, migratory paths and distant feeding grounds, residency duration, habitat quality, and threats. In 2017, Scientific Advisor Dr. Frank Rivera-Milán analyzed in-water transect counts, net captures, and nesting data that STCB has collected over the years. In cooperation with STCB, Rivera-Milán will produce scientific publications in the coming years, as well as review STCB’s methodology for netting (net captures), in-water surveys (transect counts) and nesting. 

During the 2017 season, we recorded 78 nests at our index beach on Klein Bonaire. A total of 61 hawksbill and 17 loggerhead nests and suspected nests were documented on “No Name Beach”. On the beaches on Bonaire and Klein Bonaire combined, we observed three sea turtle species (hawksbills, loggerheads and green turtles) crawling 228 times, which included a total of 128 confirmed or suspected nests. 21 green turtle nests were recorded in northeastern Bonaire. Hawksbills and loggerheads mainly nested on Klein Bonaire and the beaches of southern Bonaire. That said, three loggerhead and three hawksbill nests were recorded in northeastern Bonaire. The nesting period on Bonaire in 2017 ran from April to December with the highest number of nests laid between mid-June and mid-September. 

Estimates of clutch size and hatch success suggest that around 12,155 turtles hatched from nests on Klein Bonaire and Bonaire in 2017, including approximately 7,988 hawksbills, 2,033 loggerheads, and 2,134 green turtles. Sea turtle nesting activities across Klein Bonaire and Bonaire have been increasing since monitoring began in 2002. 

During in-water snorkel surveys, we counted and, when possible, captured green turtles and hawksbills in all regions sampled, including Klein Bonaire, along the west coast of Bonaire, and near the reef bordering Lac. Netting in Lac was conducted in three weekly sessions across the year. The aggregation of green turtles near Lac remains much larger than sites along the west coast, and greens captured there were bigger than conspecifics elsewhere, perhaps a result of the composition and high densities of sea grasses in Lac. 

The total occurrence of fibropapillomatosis (FP) among green turtles captured in nets at Lac declined considerably in 2017, continuing the downwards trend observed in 2015. This year only 5.5% of green turtles captured in and around Lac had visible FP tumors. 

STCB co-authored an important research paper in 2017: “Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic” together with researchers led by Karen A. Bjorndal.

During 2017, there were 35 sea turtle hotline incidents reported, 32 of which were directly related to turtles in trouble; one involved the general public harassing sea turtles; and one call was related to poaching. The fishing industry and associated by-catch, one of the biggest threats Caribbean-wide, was implicated in approximately 23% of the turtles in trouble. A total of nine incidents were related to a large mass of seaweed sargassum that drifted inside the Lagoen and Sorobon area at the end of December. In the open ocean, these floating mats are extremely diverse, providing important habitat for over 250 species of fish and invertebrates, many of which are not found anywhere else. Young sea turtles often spend their tender years finding refuge and a plentiful food supply in these floating seaweed mats. However, when it enters coastal areas and starts rotting, it can cause mortality. Unfortunately, climate change has brought warmer temperatures, which increases algal growth rates, and possibly stronger currents/shifting currents, which combined with more and more land-based nutrients flowing into our oceans, are thought to be the reason why we are seeing more and more massive ‘strandings’ of these floating seaweed mats.

Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long-lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio-temporal effects on hawksbill growth dynamics over a 33-yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio-temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region-wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0- or 1-yr lags: positive with the Multivariate El Niño Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs.

Sea Turtle Conservation Bonaire (STCB) has been protecting sea turtles on Bonaire since 1991, so this year represents the 25th Anniversary of our organization. In 2002 we standardized our research and monitoring efforts, following the appointment of a Scientific Officer. Annually we monitor our nesting beaches around Bonaire, conduct intensive in-water netting and snorkel surveys (capture-mark-recapture), and we regularly track sub-adult and post-breeding migrations using satellite telemetry. These techniques provide us with a better understanding of Bonaire sea turtles’ breeding success, abundance, health, growth rates, migratory paths and distant feeding grounds, residency duration, habitat quality, and threats. 

Sea Turtle Conservation Bonaire (STCB) was formed in 1991 in order to protect the island’s marine turtle populations. In 2002 we standardized our research and monitoring efforts, following the appointment of a Scientific Officer. Annually we monitor our nesting beaches around Bonaire, conduct intensive in-water netting and snorkel surveys (capture-mark- recapture), and track post-breeding migration using satellite telemetry. These techniques provide us with a better understanding of Bonaire sea turtles’ breeding success, abundance, health, growth rates, migratory paths and distant feeding grounds, residency duration, habitat quality, and threats.

During the 2015 season, we recorded 56 nests at our index beach on Klein Bonaire. Total hawksbill (46) and loggerhead (10) nests documented there were once again similar to numbers observed during recent years. Across Bonaire and Klein Bonaire, we observed three sea turtle species crawling 233 times, which includes 77 confirmed or suspected nests. Eight green turtle nests were recorded in northeastern Bonaire with a further five green turtle nests on Klein Bonaire. Hawksbills and loggerheads exclusively nested on Klein Bonaire and the beaches of southern Bonaire. Total nesting activities peaked from mid-June through to mid-September, with nests being laid between April and the end of December 2015.

We continue to be concerned about false crawls (unsuccessful nesting attempts) for both hawksbills and loggerheads as we again documented a much higher number of false crawls in 2015 than in 2013 when our concerns first developed. This phenomenon may result from a small number of individuals which were inefficient nesters (i.e., false crawled multiple times before successfully laying a nest), disturbance to turtles during nesting, and/or indicate deterioration in the quality of particular nesting sites, perhaps due to factors such as presence of an invasive vegetation species on our index beach. Estimates of clutch size and hatch success suggest that nearly 8,170 sea turtles hatched on the beaches of Bonaire and Klein Bonaire during 2015, including some 5,170 hawksbills, 1,700 loggerheads and 1,300 green turtles.

During in-water snorkel surveys, we observed and captured green turtles and hawksbills in all regions sampled, including Klein Bonaire, along the west coast of Bonaire, and near the reef bordering Lac. This year netting in Lac was conducted in four weekly sessions across the year, as a result of research in 2014 that suggested this may be a more effective sampling strategy. The aggregation of green turtles near Lac remains much larger than sites along the west coast, and greens captured there were bigger than conspecifics elsewhere, perhaps a result of the composition and high densities of sea grasses in Lac.

The total prevalence of fibropapillomatosis (FP) among green turtles captured in nets at Lac and Lagoen marginally declined in 2015 for the first time in five years, although there were still nearly a third of captures in the nets observed to have external tumors present (30%). The highest incidence was at Lagoen where six of the seven green turtles captured in the net there were observed with external FP tumors.

During 2015 STCB began the fieldwork component of a five-year research program in partnership with a research team funded by the Dutch National Research Organization (NWO) to study connectivity among sea turtles between the Dutch Caribbean Islands. As part of this research, satellite tags were fixed to four sub-adult green turtles; 19 nests were equipped with temperature loggers; and a long term experiment was set up in Lac Cai to learn more about turtle grazing and seagrass productivity there.

There were 27 sea turtle hotline stranding incidents reported during 2015, involving 35 individual sea turtles. Once again, one of the biggest threats Caribbean-wide to sea turtles was the fishing industry and associated by-catch. There were two turtles in trouble in separate incidents requiring rehabilitation early in 2015, including an olive ridley sea turtle which was successfully returned to the wild post rehabilitation. 

Raw data of sea turtle in-water-catch monitoring on Bonaire, including locations, species, carapace size, diseases, parasites, etc.

Please contact STCB for more information.

Raw data of sea turtle nesting monitoring on Bonaire, including nesting efforts, nest locations, species, number of eggs, number of hatchlings, etc.

Please contact STCB for more information.

Sea Turtle Conservation Bonaire (STCB) was initiated in the early 1990s to protect the island’s marine turtle populations. Our current research and monitoring efforts, which were standardized more than a decade ago, include monitoring important nesting beaches around Bonaire, conducting intensive in-water netting and snorkel surveys (capture-markrecapture), and tracking post-breeding turtle migration using satellite telemetry. These techniques provide us with a better understanding of Bonaire sea turtles’ breeding success, abundance, health, residency duration, habitat quality, growth rates, migratory paths, distant feeding grounds, and threats.
During the 2013 season, we observed 77 nests at our index beach on Klein Bonaire. Total hawksbill (54) and loggerhead (23) nests documented there were similar to numbers observed during recent years. Across Bonaire and Klein Bonaire, we observed four species crawling 231 times, including 126 confirmed or suspected nests. Because our coverage of the island was not complete and weather conditions can quickly obscure crawls, these nation-wide figures represent the minimum number of crawls and nests that occurred on Bonaire and Klein Bonaire during 2013. As in previous years, nesting activities peaked during June through August. Thirty-four green turtle nests and a single leatherback nest were recorded in northeastern Bonaire, whereas hawksbills and loggerheads primarily nested on Klein Bonaire and beaches of southern Bonaire.
We observed green turtles and hawksbills along the west coast of Bonaire, around Klein Bonaire, and adjacent to Lac during snorkel surveys. Green turtle sightings were particularly high near Lac, and netting surveys also suggested large aggregations of green turtles in shallow, sea grass foraging sites of Lac. Green turtles documented there were larger than individuals reported elsewhere in Bonaire.
Five green turtles tagged in 2003 and 2006 were reported in Nicaragua’s sea turtle harvest, valuable data about sea turtle movements which complement our satellite tracking program. Unfortunately, incidences of fibropapillomatosis among green turtles were more widespread in 2013 than recent seasons.
In 2013, we tracked a post-nesting female hawksbill turtle using satellite telemetry from Bonaire to Honduras over a period of 85 days. The turtle passed through six national territorial waters, swimming over 5,000 km (3,000 mi) to reach a general area proven to be important foraging grounds for Bonaire breeding turtles.
We also outfitted a hawksbill with a datalogger to gather information on hawksbill habitat use and behaviors. The device, which collects GPS locations and depth information, was retrieved in July, 2013. Preliminary results are consistent with previously deployed dataloggers, indicating regular movements in and out of Lac Bay.
Sadly, we recorded 18 turtles stranded during 2013, 12 of which were found dead or had to be euthanized.
We will be undertaking several new research initiatives in the year ahead, including using our tagging data to estimate the total population of sea turtles using Bonaire’s waters (which will help to inform management policy) and to estimate the tremendous growth rates of green turtles in Lac, as well as reviewing our monitoring program to ensure that protocols are as efficient as possible.

Sea Turtle Conservation Bonaire (STCB) was initiated in the early 1990s to protect the island’s marine turtle populations. Our current research and monitoring efforts, which were standardized more than a decade ago, include monitoring nesting beaches around Bonaire, conducting intensive in-water netting and snorkel surveys (capture-mark-recapture), and tracking post-breeding migration using satellite telemetry. These techniques provide us with a better understanding of Bonaire sea turtles’ breeding success, abundance, health, growth rates, migratory paths and distant feeding grounds, residency duration, habitat quality, and threats.
During the 2014 season, we recorded 63 nests at our index beach on Klein Bonaire. Total hawksbill (45) and loggerhead (18) nests documented there were similar to numbers observed during recent years. Across Bonaire and Klein Bonaire, we observed three species crawling 260 times, including 83 confirmed or suspected nests. Only two green turtle nests were recorded in northeastern Bonaire, whereas hawksbills and loggerheads exclusively nested on Klein Bonaire and the beaches of southern Bonaire. Total nesting activities peaked during June through August, with nesting extending through December.
We documented a much higher number of false crawls (unsuccessful nesting attempts) for both hawksbills and loggerheads in 2014 than in 2013. This phenomenon may result from a small number of individuals which were inefficient nesters (i.e., false crawled multiple times before successfully laying a nest), disturbance to turtles during nesting, and / or indicate deterioration in the quality of particular nesting sites, perhaps due to factors such as removal of vegetation. Estimates of clutch size and hatch success suggest that nearly 8,700 turtles hatched on the beaches of Bonaire and Klein Bonaire during 2014, including some 6,300 hawksbills, 2,200 loggerheads and 160 green turtles.
During in-water snorkel surveys, we observed and captured green turtles and hawksbills in all regions sampled, including Klein Bonaire, along the west coast of Bonaire, and near the reef bordering Lac. Netting in Lac and Lagoen resulted in a record number of captures during 2014, primarily green turtles. The aggregation of green turtles near Lac remains much larger than sites along the west coast, and greens captured there were bigger than conspecifics elsewhere, perhaps a result of the composition and high densities of sea grasses in Lac. Analysis of the 2013 and 2014 capture data from Lac indicates that netting during the second week of a two-week session is less efficient at capturing turtles. These results suggest that conducting netting sessions during non-consecutive weeks may be a more effective sampling strategy.
We received reports from the WIDECAST Marine Turtle Tagging Centre of 5 green turtles caught in nets by Nicaraguan fishers in the sea turtle harvest during the past 18 months. These recoveries provide invaluable information about international movements and migratory behaviors. The prevalence of fibropapillomatosis (FP) among green turtles captured in and near Lac again increased in 2014, as roughly one-third of all captures were observed with external tumors. However, we recaptured two green turtles that were previously treated to eliminate the fibropapilloma tumors. In both cases, the results were positive, perhaps suggesting that removing tumors via surgery or ligation can improve the health of individual turtles and reduce the incidence of FP in Lac.
 
Retreived from http://www.bonaireturtles.org on April 13, 2015

We observed green turtles and hawksbills along the west coast of Bonaire, around Klein 
Bonaire, and adjacent to Lac during snorkel surveys. Green turtle sightings were 
particularly high near Lac, and netting surveys also suggested large aggregations of green 
turtles in shallow, sea grass foraging sites of Lac. Green turtles documented there were 
larger than individuals reported elsewhere in Bonaire. 
Five green turtles tagged in 2003 and 2006 were reported in Nicaragua’s sea turtle harvest, 
valuable data about sea turtle movements which complement our satellite tracking 
program. Unfortunately, incidences of fibropapillomatosis among green turtles were more 
widespread in 2013 than recent seasons. 
In 2013, we tracked a post-nesting female hawksbill turtle using satellite telemetry from 
Bonaire to Honduras over a period of 85 days. The turtle passed through six national 
territorial waters, swimming over 5,000 km (3,000 mi) to reach a general area proven to be 
important foraging grounds for Bonaire breeding turtles. 
We also outfitted a hawksbill with a datalogger to gather information on hawksbill habitat 
use and behaviors. The device, which collects GPS locations and depth information, was 
We observed green turtles and hawksbills along the west coast of Bonaire, around Klein 
Bonaire, and adjacent to Lac during snorkel surveys. Green turtle sightings were 
particularly high near Lac, and netting surveys also suggested large aggregations of green 
turtles in shallow, sea grass foraging sites of Lac. Green turtles documented there were 
larger than individuals reported elsewhere in Bonaire. 
Five green turtles tagged in 2003 and 2006 were reported in Nicaragua’s sea turtle harvest, 
valuable data about sea turtle movements which complement our satellite tracking 
program. Unfortunately, incidences of fibropapillomatosis among green turtles were more 
widespread in 2013 than recent seasons. 
In 2013, we tracked a post-nesting female hawksbill turtle using satellite telemetry from 
Bonaire to Honduras over a period of 85 days. The turtle passed through six national 
territorial waters, swimming over 5,000 km (3,000 mi) to reach a general area proven to be 
important foraging grounds for Bonaire breeding turtles. 
We also outfitted a hawksbill with a datalogger to gather information on hawksbill habitat 
use and behaviors. The device, which collects GPS locations and depth information, was 
retrieved in July, 2013. Preliminary results are consistent with previously deployed 
dataloggers, indicating regular movements in and out of Lac Bay. 
Sadly, we recorded 18 turtles stranded during 2013, 12 of which were found dead or had to 
be euthanized. 
We will be undertaking several new research initiatives in the year ahead, including using 
our tagging data to estimate the total population of sea turtles using Bonaire’s waters 
(which will help to inform management policy) and to estimate the tremendous growth 
rates of green turtles in Lac, as well as reviewing our monitoring program to ensure that 
protocols are as efficient as possible. 
 

2005 was a very successful year for Sea Turtle Conservation Bonaire as we built upon the accomplishments of 2004. In all the program areas, staff and volunteers worked hard to move us forward in pursuit of our mission: to ensure the protection and recovery of Bonaire’s sea turtle population throughout their range.

On the research front, we observed sea turtle nesting in 2005 at lower levels than during 2004, with a total of 61 nests recorded for all the beaches of Bonaire and Klein Bonaire. The in-water surveys on the turtle foraging grounds yielded a total of 105 turtles handled, of which 21 were recaptures from 2003 and 2004. Satellite tracking of breeding turtles was again a success, with four turtles fitted with transmitters: three on hawksbills and one on a loggerhead turtle, all at Klein Bonaire. We successfully followed all tracked turtles during their long-distance migrations to their foraging grounds. We generated daily maps and gave relevant information via our newsletter to the public, creating awareness about the situation of the sea turtles around the globe.

In the area of education and public awareness, our year long education and outreach campaign that started in 2004 and done in collaboration with the Dutch Caribbean Nature Alliance, STINAPA Bonaire, and Coral Resource Management was completed. The very successful and well-received campaign focused on sea turtles and provided a year of constant attention through the distribution of newsletters, posters, flyers, buttons, school and community presentations, beach clean-ups and press releases. Our regularly scheduled ‘Sea Turtles of Bonaire’ slide presentation continued to draw the interested public. During the year, we generated a record number of press releases in our effort to bring attention to sea turtle conservation and alert the public to vital issues.

This last year we were able to take a step forward in the organizational arena. Our staff team grew with the addition of Dr. Robert van Dam as our Scientist Coordinator, Eric van der Keuken as our financial advisor and accountant, and a part-time field assistant. Volunteer support and assistance was significantly increased with the addition of three new island residents contributing their time and talents in a consistent fashion. We were also contacted by scores of people offering to assist on an ad-hoc basis.

Our website and electronic newsletters became important and very effective tools for us to share information about the endangered sea turtles and inform about our continuing efforts to protect these animals.