I saw this one from the letters to the DFG, but felt it needed further review. Shooting a paintball at a Sea Lion is OK? Huh?

legally this boat owner could have had some target practice

Question: If I am fishing and am continually harassed by seals and sea lions, is it lawful to shoot them with a non-lethal paint ball? (T. Jay D.)

Answer: DFG does not manage or regulate interactions with marine mammals. California sea lions and Pacific harbor seals have been federally protected under the Marine Mammal Protection Act since 1972, and thus harassing, capturing, killing or attempting to do so is prohibited and carries a hefty fine ($10,000). According to the National Oceanic and Atmospheric Administration (NOAA), in recent years the populations of these animals have increased dramatically and are now considered healthy and robust.

Unfortunately, with the good often comes the bad - the increased abundance of animals has also resulted in a growing number of negative interactions with humans and incidents of property damage. People seeking legal methods for deterring marine mammals in order to protect their property, fishing gear and catch from damage by sea lions and seals can find recommendations and approved methods on NOAA's Web site at http://www.nwr.noaa.gov/Marine-Mammals/Seals-and-Sea-Lions/Deterring-Pinnipeds.cfm
And yes, paint balls are an approved method that may be used under certain conditions, but please read the NOAA information before doing so.

Here's the basics :

Q. May I deter a Pacific harbor seal or California seal lion that is hauled out on a beach or breakwater, or is swimming in an area where I want to fish?
A. The MMPA does not allow private citizens to deter marine mammals from undeveloped property (e.g., a beach) or public property (e.g., a breakwater). Private citizens may deter only Pacific harbor seals and California seal lions that are exhibiting problem behavior resulting in, or that could result in, damage to private property, fishing gear or catch.

Q. Who may deter sea lions or seals?
A. In summary, certain private citizens, marina owners, government officials, and commercial and recreational fisherman may deter sea lions and seals under certain conditions, as described below:

*Private Citizens – Only the owner of the private property (e.g., a dock or vessel) may deter Pacific harbor seals and California seal lions to prevent damage to their private property.

*Commercial and Recreational Fishermen – Fishermen can deter Pacific harbor seals and California seal lions from damaging gear or depredating catch, only if they are actively fishing.

*Marina Owner – Only the marina owner, or an employee of the owner, or an agent of the owner may deter Pacific harbor seals and California seal lions to prevent damage to the marina.

*Government Officials – City, county, state or federal officials or their employees may deter listed and non-ESA-listed sea lions and seals determined to be “nuisance” animals to prevent damage to private or public property, or to protect the public from potential threats.

Endangered Species Act (ESA) -Listed Species: Steller Sea Lion (Threatened) may NOT be deterred by public

Non-ESA-Listed Species: Pacific Harbor Seal and California Sea Lion may be deterred by public

Here's a few ways of "deter":

cracker shells "deployment"

sprayer system swimstep