Do Lunar Cycles Influence Shark Attacks?

Erich Ritter1, *, Raid Amin2, Aletheia Zambesi2
1 Shark Research Institute/Florida Office, 5970 Osprey Place, Pensacola, FL 32504, USA
2 University of West Florida, Department of Mathematics & Statistics, 11000 University Parkway, Pensacola, FL 32514, USA

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© 2013 Ritter et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Shark Research Institute/ Florida Office, 5970 Osprey Place, Pensacola, FL 32504, USA; Tel: 28609292092120505; Fax: 6099211505; E-mail:


One recurring factor seemingly causing an increase in shark attacks is lunar cycles, especially the full moon. However, the potential association between shark attacks and lunar cycles has never been verified. Our results show that a correlation between shark attacks and moon cycles does not statistically exist. With no correlation between shark attack rates―independent of people's activities―and lunar cycles found, we also applied the same statistical procedures to surfer incidents only. The reasoning for narrowing the attacks to those on surfers was as follows: (1) Surfers indicate the best conditions to surf exist during the full and new moon. (2) Surfers are more exposed to shark attacks than non-surfers. However, as with the initial results, shark attacks involving surfers did not show any correlation to lunar cycles, neither did those involving non-surfers. These results indicate that potential triggers for shark attacks need to be studied in a more pragmatic manner, using, for example, mathematic approaches to test for global phenomena and then individual instances, leaving guess work largely aside.

Keywords: Full moon, lunar cycle, shark attack, tide.