Cetacean Strandings 
43 
distinct seasonality, with strandings typically occurring during the winter 
and spring months. Despite small sample sizes, the northern right whale 
(Eubalaena glacialis (Miiller)) and humpback whale (Megaptera novaeangliae 
(Borowski)) also fit into this category. The short-finned pilot whale, 
long-finned pilot whale, Risso's dolphin ( Grampus griseus G. Cuvier), 
Atlantic spotted dolphin ( Stenella frontalis G. Cuvier), rough-toothed 
dolphin ( Steno bredanensis (Lesson)), and dwarf sperm whale ( Kogia 
simus (Owen)) display significiant monthly variation in stranding with- 
out exhibiting well-defined seasonal patterns. Not included in Table 
1 are Bryde’s whale (Balaenoptera edeni Anderson), blue whale (. B . 
musculus (Linnaeus)), and short-snouted spinner dolphin ( Stenella clymene 
(Gray)), species that have stranded to the north and south of North 
Carolina but not within state boundaries. Also, the pantropical spinner 
dolphin (, Stenella attenuata (Gray)) was not included because we were 
unable to verify stranding records in North Carolina. These four species 
probably inhabit state waters seasonally or as occasional strays (Lee 
et al. 1983, Webster et al. 1985). 
Overall, cetaceans strand significantly more frequently during 
the winter and spring months in North Carolina (Table 1). Several 
abiotic and biotic factors that are not necessarily related could cause 
this trend, and examples of each are apparent in these data. Winter 
storms (known as nor’easters because of the direction from which 
they blow), coupled with relatively colder water temperatures that 
slow the process of decomposition, increase the likelihood that a carcass 
will wash ashore during the winter and spring months. Also, circum- 
stantial evidence suggests that mortality may be greater for some species 
during the winter and spring months. Finally, certain species of ceta- 
ceans are clearly more abundant during the colder months of the year, 
thus increasing the likelihood of finding stranded animals. 
Stranding records for the bottlenose dolphin comprise almost 61% 
of the total number of cetacean strands reported from North Carolina. 
Bottlenose dolphin strandings increase during the winter and spring 
months as local neritic populations are augmented by more northerly 
inshore and pelagic populations (True 1891, Schmidly 1981, Kenney 
1990). Increased winter and spring strandings might simply be an 
artifact of a larger population during those seasons of the year or 
mortality rates might be greater during the winter months. Significant 
stranding increases associated with the dolphin die-off of August- 
October 1987, when the brevetoxin from the dinoflagellate ( Ptychodiscus 
brevis) weakened dolphins such that they contracted lethal secondary 
bacterial and fungal infection (Geraci 1989), were clearly evident (Fig. 
i). 
