This heatmap shows which days all recorded shark encounters between 1959- 2018 have landed on a single calendar

Here we can see seasonality really begin to take shape. Some of the interesting takeaways for me on this one:

• Most encounters happen not only in the summer months when more people are in the water, but also on the weekends

• I expected to see more encounters in the winter when more adults are present in Northern California feeding on seals and are closer to the shores

• We can see that the ‘safer’ months appear to be winter through spring

Another interesting result from this plot is that the intersection between human behavior and shark behavior comes into view. The two most important factors of considering shark encounters are how many people are in the water at the same time that sharks are nearby. We know that in Southern California baby sharks are around in the summer months feeding on stingrays and other fish. This is also the same time that most people in Southern California are going into the water. It is also believed that younger sharks have not learned yet that humans are not a good source of food and may be responsible for a large percentage of attacks in Southern California by way of ‘investigative bites.’

On a personal note: despite what this plot shows, I’m still wary of the winter months in Northern California. There are regular shark sightings all through winter in Northern California, whether there are recorded incidents or not. Also, I believe a big reason why there are less incidents in the winter is because there are far less people in the water.