‘WELL SPOTTED’: PANTROPICAL SPOTTED DOLPHINS IN ABACO
Two species of spotted dolphin are found in Bahamas waters. The most common is the ATLANTIC SPOTTED DOLPHIN Stenella frontalis, a species confined to the Atlantic. Less commonly seen – though with a global range – are Pantropical Spotted Dolphins Stenella attenuata.
The BMMRO research boat is out whale-spotting right now, and the team is finding a good variety of cetacean species, from dolphins right up to SPERM WHALE mother and calves. A couple of days ago, the pantropicals surfaced and these great shots of them were taken.
The two spotted dolphin species are very similar to the untrained eye. Identification is further complicated by the fact that both species start life without spots and go through stages ranging from no spots at all to completely spotted. These stages are sometimes referred to as ‘two-tone, speckled, mottled, and fused’. The pantropicals are relatively small, reaching lengths up to 7 feet and weighing c250 pounds at adulthood. Their beaks are longer and more slender than the familiar but larger bottlenose dolphin. The beak has a white tip, a useful identifier.
Atlantic Spotted and Pantropical Spotted range maps for comparison
The pantropicals favour shallower water by day, and at night they move to deeper water where they can dive down for food such as squid. Although they are IUCN listed as ‘Least Concern’ and their world-wide numbers are estimated to be abundant, they face the usual man-related threats to the species throughout their range, especially in the Pacific region. As we see time after time, complacency can turn to concern in a very short time.
THREATS TO THE SPECIES
- Entanglement in fishing gear – captured as bycatch in the course of commercial fishing
- Entangled in discarded fishing gear
- Illegal feeding and harassment – this is a problem in particular locations eg Hawaii
- Overexposure to and interaction with eager tourists in inshore areas
- Hunting – these dolphins are prolifically hunted for food in several parts of the world
- Hunting – they are caught ‘accidentally’ in large numbers in nets set for tuna
- Persecution in eastern tropical Pacific fisheries, according to WDC
- Pollution, plastic ingestion etc – basically, mankind’s negligence over 60 years or so
- General habitat degradation, disturbance and marine noise pollution – mankind again
Credits: BMMRO for all photos; research credits NOAA; WDC