THE VIRGINIAN-PILOT
Copyright (c) 1996, Landmark Communications, Inc.
DATE: Sunday, January 21, 1996 TAG: 9601210048
SECTION: LOCAL PAGE: B5 EDITION: FINAL
SOURCE: BY DEBBIE MESSINA, STAFF WRITER
DATELINE: VIRGINIA BEACH LENGTH: Medium: 80 lines
Marine researchers have found that for the third consecutive year about 75 percent of all bottlenose dolphins that summer off Virginia's coast prefer Virginia Beach's waters.
After analyzing the data from last summer's third annual dolphin count, Virginia Marine Science Museum scientists this month validated earlier beliefs that the state's dolphin population is concentrated in Virginia Beach.
``It's been so close it's weird,'' marine biologist W. Mark Swingle said of the distribution. ``It's been within a few percentage points, between 75 and 80 percent.''
Swingle, leader of local dolphin research, cannot yet explain the uneven distribution but said water temperature and food sources are potential factors.
Preliminary numbers from the July count show that 795 dolphins were recorded along 120 miles of Virginia coastline. However, after a recently completed analysis that eliminates duplicate counts of the same animals, the number dropped to 485.
In 1994, the analyzed count was 407. In 1993, 335 were counted. These are only estimates. It's difficult to count dolphins, as they spend 90 percent of their time under water and are in constant motion.
While the number is steadily increasing, Swingle said that he cannot say that means there are more dolphins.
``We cannot make a strong, verifiable conclusion as far as abundance goes,'' he said. ``We don't know enough yet as to what these numbers mean.''
When you break these numbers down further to a one-hour count, the numbers have remained more steady. The one-hour count was 165 in 1995. It was 161 in 1994, and 188 in 1993.
``Because these are so similar, that leads us to believe there is no major increasing or decreasing trend here,'' Swingle said.
The larger, overall counts represent several hours on a Saturday morning of scanning the ocean, counting dorsal fins and tail flukes. The likelihood of duplicate counts increases over a longer period of time. And each year, volunteers are spending more hours on the beaches conducting their counts.
What's proven to be more significant than the actual numbers is the distribution of where the dolphins were spotted.
The count indicates that there are few animals north of the Chesapeake Bay, which at first surprised researchers. They expected to find greater concentrations of our finned friends off the Eastern Shore's barren barrier islands.
They assumed the dolphins would be attracted to the Eastern Shore's pristine habitat, undisturbed by major shipping channels, hordes of tourists or high rise hotels looming over the shoreline.
Instead, most of the dolphins have been spotted along Virginia Beach's coast. The greatest concentration each year has been at Cape Henry, the northern tip of the city. The numbers and energetic activities of dolphins at Cape Henry has inspired researchers to name the point ``Dolphin Disneyland.''
One possible explanation, Swingle said, is that the food-rich waters around the mouth of the Chesapeake Bay attract dolphins, which feed mostly on fish - primarily spot, croaker and trout.
The bottlenose dolphin's population was designated as ``depleted'' by the National Marine Fisheries Service as a result of the 1987-88 dolphin deaths, in which about 750 dolphins died along the East Coast. It was the largest mass poisoning of marine mammals on record.
The counts will help piece together the mystery surrounding the bottlenose dolphin, the most common, yet one of the least understood, marine mammals on the East Coast.
Virginia is a critical area for studying the coastal migratory dolphin population. South of Cape Hatteras, dolphins live near shore year round. But in Virginia, coastal dolphins appear in May and leave in November.
The Virginia Marine Science Museum has taken the lead in the effort to learn more about the number and migration of these dolphins. The ultimate goal of the research is to conserve the species. ILLUSTRATION: Photo
CHARLIE MEADS/The Virginian-Pilot file
For the third year, researchers say, 75 percent of the bottlenose
dolphins that visit Virginia in the summer hang out off Virginia
Beach. Their numbers have remained fairly constant over that time.
by CNB