I was looking for a study from Appalachian St U, but I can't spell Applalachian
http://www.sportsci.org/news/compeat/fat.html
RESPONSE TO HOT AND COLD SWIMMING ENVIRONMENTS
Neilsen, B. (1977). Physiology of thermoregulation during swimming. In B. Eriksson & B. Furberg (Eds.), Swimming Medicine IV - Proceedings of the Fourth International Congress on Swimming Medicine. Baltimore, MD: University Park Press.
EFFECTS OF SWIMMING ON ANTHROPOMETRIC MEASURES AND FAT ACCUMULATION
Avlonitou, E., Georgiou, E., Douskas, G., & Louizi, A. (1997). Estimation of body composition in competitive swimmers by means of three different techniques. International Journal of Sports Medicine, 18, 363-368.
Sorry no time for more...this quote from an inconclusive study....is my POV, JMHO
It is commonly reported that swimmers store greater amounts of body fat than runners.