Five Harbour Seals at The Bermuda Aquarium, Museum & Zoo are causing a storm in scientific circles.

The seals were thought to have only a short and rigidly timed reproductive cycle, but research at the Aquarium has shown otherwise.

And last month, volunteer associate Jamie Bacon presented the findings to the World Marine Mammal Conference in Monaco where the news went down like a storm.

"The response at the workshop was overwhelming,'' Dr. Bacon said.

"I found that our results will not just affect future work with Harbour Seals, but they are going to have considerable significance for current studies being done on Hawaiian monk seals and grey seals as well.

"The data obtained showed a number of important things. It provides the first hormonal evidence which shows that individual females can be either monoestrus or polyoestrus.'' Dr. Bacon also explained that if during seal's heat she was unable to mate and the ovum matured and was passed through the body, a second oestrus cycle could start.

"It's like having a reproductive spare tyre,'' she said.

Harbour Seals are native to the North Atlantic and range from Rhode Island in the United States all the way to the Canadian Arctic.

And although they have been seen as far south as Florida and once in Bermuda in the 1800s -- when one was shot and killed -- having the seals in captivity in warm Bermuda has caused a situation ripe for study.

Aquarium officials give the lone male, Archie, contraceptive injections to keep the population manageable. Archie and his harem eat 60,000 pounds of imported herring a year.

"Our intentions were to determine the timing and duration of the reproductive cycle in our female seals in order to ensure that we could prevent further reproduction,'' Dr. Bacon explained.

She and the other volunteers have discovered that their practice of keeping Archie segregated from the females for part of the summer prompts a second oestrus period.

Conventional wisdom held that the animals had only one and it was timed for mid June, shortly before the warmest time of year in the arctic and north Atlantic.

"Our research showed that each animal had an individual variability,'' Dr.

Bacon explained.

"Two females were showing one cycle and two were showing two oestrus cycles that were delayed.'' The report centres around three findings: Individual variability; Induced ovulation; and Certain seals having a second oestrus.

Dr. Bacon explained that humans have spontaneous oestrus cycles and the animal kingdom has animals with spontaneous cycles or cycles induced by natural stimuli.

"Calico was separated from Archie but did have her expected ovulation,'' she continued. "When he was put in she entered a second oestrus and ovulated, which they are not supposed to do.'' The surprising findings were submitted for peer review, but were not entirely new.

Dr. Bacon said a scientist in the 1970s did seem to pick up two cycles, but did not have concrete hormonal evidence and his work was forgotten.

"We just have better proof!'' Dr. Bacon explained. "And with his findings we're not out on a limb.''