Utilizing Air-Scenting Search Dogs to Locate Drowning Victims: A Research Report
Prepared by: Alice J. Stanley
Virginia Search and Rescue Dog Association (ARDA-VA)
Part 2 of 2
Part II: Totally-Submerged Subjects
Case #1: A 16-year-old girl had become separated from her hiking companions along Whiteoak Canyon in the Shenandoah National Park, and the Virginia Unit's assistance was requested, with three dog/handler teams responding. Dogs were deployed along the ridges and stream which ran the length of the two mile Canyon, utilizing an "overlapping" technique wherein handlers exchanged areas during the course of the day.
All three dogs "alerted" (indicated the presence of human scent) at various points along the stream and, late in the afternoon, one dog made a pronounced alert at the base of a waterfall which was the PLS (her companions had left her sitting on a rock in the middle of the stream below the falls). Although the pool at the base of the falls had been dragged twice during the day, divers were requested to check it because of the dogs' continued interest. The girl's body was subsequently recovered and it appeared she had attempted to jump from the rock to the trail, slipped, and was held under by the strong current when her leg became wedged between two rocks. She had been submerged 24 hours at the time of the strong alert and the water depth was four to six feet.
Case #2: The New Jersey Unit was requested to aid in the search for a young boy who drowned while swimming with three companions. The boys had boarded a raft, which was tied near the dam of a man-made lake. As the raft began drifting farther from shore, the boys jumped overboard in an attempt to swim to the dam. Three made it to the dam, and realized the fourth had disappeared.
One dog/handler team began working across the dam and, after proceeding about 200 feet, the dog made a strong alert at the opening of a concrete shaftway. The dog immediately picked up a stick to play (ARDA dogs are trained using the play-reward system). He then made several attempts to enter the water, which was two feet below the top of the dam. The dog was allowed to enter the water just beyond the shaftway and directed to swim back past the structure. When he was about thirty feet past it, the dog suddenly whirled around 180 degrees as though he had a definite scent, went several feet back toward the shaftway and then whirled again. Search efforts in the alert area with grappling hooks produced negative results. Several days later, a worker opened a sluiceway immediately below the alert area and the boy's body was propelled from the dam in the surge of water. Time missing when the alert was recorded was five days and the water depth was 35 feet.
Case #3: Two teenaged brothers failed to return from a canoe trip on a large river in northern Virginia, and the Virginia Unit's assistance was requested in searching the heavily wooded shoreline on both sides of the river. One dog made an extremely pronounced alert from the shore toward the water, several hundred yards upstream above an inlet where the boys' empty canoe had been found. Other dogs were brought in by boat and from the shore and all alerted in the same area. Search efforts by dragging and diving were restricted by debris and murky water conditions. One week after the Virginia Unit's search, both boys surfaced in the alert area approximately 60 feet from shore. They had been submerged three weeks at the time of the alert, and the water depth was 60 feet.
Case #4: Two men were overdue from a fishing trip on Lake Gaston in North Carolina. Their boat had been found capsized by a large power dam on Saturday morning, and a witness reported seeing the craft floating in the middle of the lake on Friday evening. Three Virginia Unit dog/handler teams began systematic sweeps by boat over the 200 acre area of water, and one dog consistently alerted at a point in the middle of the lake. During the day, the other two dogs were taken through the area and both made strong alerts.
Another dog had made an alert near a point of land across the lake from the dam and subsequent checks with the other dogs produced the same results. Markers were dropped at the site of the mid-lake alert and dragging operations were begun. One rescue worker reported picking up something "buoyant", but was unable to recover it. A boat equipped with a "fish finder" was taken through the area and the device indicated something floating five feet off the bottom. Two weeks later, one body was found floating in the area of alerts near the point of land, and three days later the second body surfaced by the mid-lake alert markers with dragging hook marks on the face. The subjects had been submerged six days at the time of the Virginia Unit's search and the water depth was 75 feet.
Case #5: A 17-year-old boy drowned in a man-made lake when thrown from his capsizing boat. Witnesses designated the general area and divers began search operations. Eight days after the boy's loss, the Virginia Unit's assistance was requested and four dog/handler teams responded. Two dogs were placed on a "pontoon" boat and began a sweep parallel to the shoreline. They began alerting some distance to the north of the original search area and subsequent sweeps with the other two dogs produced the same results. Additional sweeps consistently produced alerts, even when the area was approached from directions other than downwind.
Diving efforts were moved to the alert area and the following day, as divers prepared to continue their search, the subject surfaced on the perimeter of the alert area. It is assumed the body had started to rise as the divers began searching the bottom and they apparently passed under him on their first sweep through the area. It should also be noted that on the day of the Virginia Unit's search, a boat equipped with a fish finder had moved through the alert area and received a reading of an object floating at a depth of 25 feet in the middle of the area, although the subject surfaced approximately 100 feet from the site of the reading. The water depth in the search area was 35 feet.
Conclusions: Experience has shown that scent behavior in water is such that the exact location of the subject is often impossible to pinpoint with the dogs. Surface current and wind conditions can carry scent several hundred feet and repeated passes with the dogs from different directions have proven the most effective in reducing the area. Underwater contours may also "funnel" the scent to the shoreline, where it may cling to shore vegetation. There have two been instances where the subject surfaced some distance (100 feet or more) from the alert area, but it is believed the bodies drifted or were propelled by "prop wash" from passing boats as they began to rise to the surface. In those cases, two or more days had passed since the dog search and there had been heavy boat traffic in that time span as dragging operations continued. In one of these searches, a boat with a powerful inboard motor was requested to circle through the area in an effort to bring the subject to the surface (the diving team had experienced previous success with this method). There is a possibility the subject did move but failed to surface. In this same search, the dog efforts did in fact move the search effort closer to where the subject surfaced than the area being worked prior to the dogs' arrival.
Air-scenting dogs have proven effective in those cases where a large area of water must be reduced for effective use of manpower. Scent behavior in water is a relatively unknown entity and the scent itself must be assumed to be body gases being carried to the surface on oxygen bubbles. How much effect underwater currents or contours have on scent behavior can only be a matter of conjecture and this must be considered by search managers when committing resources. However, the dogs have in most cases narrowed the search area to within 100 feet or less of the subject's location. Recovery techniques have produced the greatest difficulty in "proving" the dogs, as dragging and diving efforts often work only the bottom and are hindered by debris and murky water. If the subject has started to rise, these methods may easily fail and recovery becomes a matter of waiting until the body surfaces. "Fishfinders" or some portable sonar devices may prove helpful in pinpointing the subject once the dogs have indicated the general area. As stated before, the body may be moved by currents or boat traffic and verification of the dogs' alerts in those instances is impossible. In most cases to date, however, the subject has been found in the alert area.
It should also be noted that the success of the dog efforts in deep water may be greater after the subject has been submerged for several days due to excessive scent buildup and more pronounced release of body gases. The strongest, most accurate alerts in water 35 feet or deeper have been after 48 hours have passed since the drowning occurred.
Although more research must be done in an effort to determine scent behavior in water, it appears that air-scenting dogs are capable of locating drowning victims and may provide an effective additional resource to those faced with this difficult search situation.
Page 1: Partially-Submerged Subjects