There are not enough fish this year.
Due to the low number of specimens monitored by the SEMARNAT (Secretariat of the Environment and Natural Resources), the tourist activity of swimming with whale sharks is suspended until further notice.
There aren't enough whale sharks present. This is rare, but it has happened in the past.
Whale sharks are endangered and protected under Mexican law. There are strict rules governing the whale shark tours, one of them being there needs to be a minimum number of them in the area. That number has dropped recently, so they need to stop offering tours until the number increases. It may be due to a drop in the water temperature, so we may need to wait awhile.
Whale sharks are the biggest sharks and the largest fish in the world, but they are endangered and under threat from unregulated fishing, in addition to entanglements in nets and vessel strikes.
Whale sharks are usually solitary creatures, although they are known to gather in large schools as they migrate to areas with an abundance of plankton and warm waters—like La Paz Bay. They are known for their friendly behavior as they will often swim alongside boats.
In some other places in the world, they are known as Grandma's shark. The name derives from the belief that the shark embodies a kind-hearted grandmother spirit. When local fishers encounter a whale shark on one of their trips, they see it as a sign of good fortune and prosperity.