Colder seas could be keeping basking sharks away from thewaters around Cornwall.
The Marine Conservation Society (MCS) said it has received hardly any reports of sightings of the sharks so far this year.
Jean-Luc Solandt, a spokesperson for the MSC, said it could be due to water temperatures being cooler than average for the time of year.
"Divers are telling us that the water temperature is 10 or 11 degrees centigrade but at this time of the year it should be nearer 13 degrees.
"This means that the plankton, which is the basking shark's favourite food and the reason they come to our waters, are not blooming in the usual quantities so basking sharks are staying in warmer seas to feed."
The seas around Cornwall are a hotspot for Basking Sharks, which are the second largest fish in the world.
Last year more than 170 sightings were reported to the MCS which runs the database Basking Shark Watch. Numbers are expected to increase in the coming months.