Survey work in the early 1990's established that many beaches on St. Croix support marine turtle nesting, but nesting was concentrated on Sandy Point NWR and the East End Beaches known as East End Bay, Isaac's Bay, and Jack's Bay.  Sandy Point had (and continues to have) a comprehensive research and monitoring program for the leatherback population.  However, significant Hawksbill (Eretmochelys imbricata) and Green (Chelonia mydas) nesting activities were being identified during daytime surveys.  Lack of funding and resources prevented nighttime monitoring.

During the 1994 nesting season, additional support was made possible under the U.S, Fish and Wildlife Service (USFWS) and National Park Service (NPS) Interagency Agreement, which allowed for the initiation of night monitoring on both Sandy Point NWR and the East End Beaches.  Nesting at Sandy Point NWR proved to be much too diffuse within the refuge for effective coverage without a large number of research personnel.  As a result, daytime surveys were carried out at Sandy Point NWR and night monitoring efforts were concentrated on the East End Beaches.  Night monitoring also revealed how limiting daytime surveys can be (Amy Mackay, 2004).  Night monitoring with saturation tagging allows researchers to better understand the population as you can track individual turtles, their nesting habits, and their fecundity (i.e. hatchling production).

These preliminary data elicited an even larger commitment from USFWS during the 1995, 1996 and 1997 nesting seasons.  However, once baseline monitoring was completed only partial funding was available for the 1998-2000 seasons.  In 1999, The Nature Conservancy (TNC) purchased the 300 acres that make up Jack’s and Isaac’s Bay.  This area adjoins another 300 acres owned by the territorial government and creates a 600-acre protected area including the East End Beaches.  Beginning in 2001, TNC began funding sea turtle monitoring on the East End Beaches and nighttime monitoring was resumed. (Amy Mackay, 2004).

In 2005, TNC enlisted the assistance of WIMARCS to manage and operate this valuable sea turtle monitoring project.  Through TNC funding, WIMARCS continues to expand and meet its goals of protecting and conserving local marine resources on St. Croix.

This relatively narrow beach is approximately 1.0 km in length and ranges in width from approximately 3m to 15m.  This beach lacks any wave formed berm or other features associated with wave action.  Surface water runoff from the surrounding hills creates temporary gullies that cut across the beach and into the sea.  Vegetation adjacent to the beach is composed of dense stands of sea grape (Cocoloba uvifiera) mixed with thorny scrub.  The sand on this beach is typically fine-grained and compact, partially mixed with marine debris and vegetation and covered with dense mats of sandbur grass (Cenchrus incertus) and sea purslane (Sesuvium portulacastrum).

Study Area Coverage

The East End Beaches are periodically patrolled during the day throughout the year with nighttime monitoring being carried out from August 1st through November 15th.  Daytime patrols will continue through December 15th.

Hourly patrols are conducted from 2000 hours to 0400 hours.  These patrols are conducted by a team consisting of a principal investigator and three field leaders.

Data Collection

Basic data collection procedures are similar to previous years, and follow the techniques described in the Manual of Sea Turtle Research and Conservation Techniques (Pritchard et al., 1983).

Each time a turtle is encountered a data sheet is completed.  Morphological, nesting, behavioral data, and nest parameters are recorded along with time and date of encounter.  Nests will be excavated after hatchlings emerge, and the contents categorized to determine hatching success. 

Unobserved activities are also recorded.  In these instances, an attempt is made to determine if the activity had resulted in egg deposition and the species and location are recorded.

When a turtle is observed, data is collected using the following methods:

Nesting

When a turtle is encountered, the date and time as well as the behavior at the time of sighting are recorded.  In order to minimize the potential impact on the turtle, no further information is collected until egg deposition begns. 

If a turtle leaves the beach before successful egg deposition (dry run), at least one of her tags is read before she enters the water.  If the turtle has no inconel flipper tags and no PIT tag she is considered “untagged” and at least one inconel flipper tag is applied as the turtle is leaving the beach. 

Beach marker stakes are placed every 20 meters along the vegetation of each of the three beaches.  These stakes are made from 2”x 2”x 4’ lumber and provided by The Nature Conservancy.  All of the stakes are numbered and each beach is numbered independently of the other beaches.

Nest locations are recorded by measuring the distances from the two nearest stakes.  In the event that a nest is laid behind the stake line, negative measurements are recorded.  This system has proven very useful for locating nests after emergence, without leaving any markers indicating the presence of individual nests, except when stakes are lost or removed, as is the case each season.  Because this is not a new problem, additionally, a wooden popsicle stick is labeled with the date and the turtle’s id number (one of her tag numbers) and placed in the nest to assist with nest confirmation upon excavation.  

When a previously untagged turtle or one that has lost one of its tags is encountered, tags are applied.  Ideally, each turtle leaves the beach after nesting with two external tags and one internal PIT tag.

An inconel tag (PPQ, NNV, XXX, XXZ, or RRN prefix) is applied to the posterior edge of one of the two front flippers in the most suitable scale closest to the body (usually the first or the second).  Another inconel tag is placed along the interior edge of one of the rear flippers proximal and adjacent to the first large scale.   The tags are applied so there is less than 1cm of tag extending beyond the edge of the flipper.  Tags are oriented so the tag number is on the dorsal side of the flipper.  Whenever possible, each turtle is tagged on the right front flipper and the left rear flipper.

Turtles are also tagged with a Passive Integrated Transponder (PIT) tag (Avid, 12mm).  This tag is a small, glass-encased microchip that is injected into the muscle of the front shoulder.  It is detected with a portable scanner and a tag-specific nine-digit number is read.  The tagging site is treated with Betadine before and after the injection of the PIT tag.  Tagging sites are closely examined for signs of infection during subsequent nesting activities.

During prior seasons, PIT tag application and retention are investigated by comparing two tagging sites.  As a result, some nesting females have a PIT tag in one of the front flippers, between the scales closest to the body.  However, retention in the shoulder muscle is shown to be comparable and stranded animals are often missing flippers but shoulder muscle is much more likely to be intact and available for scanning.

A blood sample is taken from each female for ongoing genetic analysis.  Blood is obtained from the dorsal cervical sinus using a sterile syringe (3cc) with a 21g x 1.5” needle.  A small amount of heparin is used to prevent clotting.  Blood samples are prepared in lysis buffer shortly after collection.  A back-up sample is also prepared and frozen.

As with PIT tagging, the sampling area is treated with Betadine before and after blood sampling.  Sampling areas are closely examined for signs of infection during subsequent nesting activities.

Sampling only takes place during egg deposition, and samples are only collected in accordance with issued endangered species permits.

Each turtle is closely examined, usually during tamping or disguising, and all identifying characteristics such as scars from old injuries, barnacles and other ectobiota, tag scars, and other diagnostic markings are recorded on the data sheet.

Standard measurements are taken including the curved carapace length and width.  Curved carapace length (CCL) is measured from the nuchal notch to the posterior tip of the carapace along the medial line.  Length is recorded to the longest side, if one posterior marginal is longer, and this information is noted on the data sheet as either right or left.  An additional carapace length is measured for hawksbills: from the nuchal notch to the notch between the pair of posterior marginal scutes (supracaudals).  (Green turtles lack a significant notch and are measured only once.)  Curved carapace (CCW) width is measured at the widest point posterior to the front flippers and perpendicular to the medial line. 

All measurements for each female are averaged for the season.

West Indies Marine Animal Research and Conservation Service, Inc.

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