Deaths among California’s sea otter populations have been increasing in the last few years. The last few years have set records for dead otters washing ashore on beaches throughout central California. The real reason for this was recently discovered (and covered earlier today by Andrew here), but I wanted to stress what was NOT responsible. For years, many people have been blaming the increased otter deaths on sharks instead of the real culprit, toxic freshwater algae. While great white sharks do bite otters, these predators are drastically declining in population. For this reason, assigning them all the blame for increased otter deaths never sat well with me- if there are fewer sharks, why are more otters being bitten by sharks? Some blame changing migration patterns of sharks due to warming seas, but that doesn’t tell the whole story. Fortunately, this mystery has been solved- toxic algae, not sharks, are responsible.
Both species (otters and great whites) are protected due to low population numbers. The suggestion by some to kill great whites to protect otters shows extremely flawed conservation logic.
I should also note that otters are not part of a great white’s usual diet. When sharks bite otters, it is usually a “test bite”. When the sharks realize that otters aren’t the more fatty seals that they resemble, the sharks usually do not bite again. Sometimes, the initial test bite can be fatal.