Gov. Jerry Brown has signed a bill to close a loophole in the state's ban on importing, buying or selling elephant ivory or rhinoceros horns.

Supporters said California is a major market for ivory, and the ban would help dry up demand.

The measure by Assembly Speaker Toni Atkins, D-San Diego, aimed to end the state's exemption for selling ivory imported before 1977. She said clamping down on the illegal ivory trade would help bring an end to the poaching of elephants and rhinoceros.

"Ninety-six elephants die every day for their ivory. Elephants and rhinos are being slaughtered at a faster rate they are being born, which will result in their extinction if we don't step up," Atkins said in a statement Sunday. "The governor's signature on AB96 strengthens enforcement against the illegal ivory trade in California, which will, in turn, help put an end to poaching."

Brown announced Sunday he signed the bill.

Critics said the legislation would do little to help if other countries and states continue allowing sales of ivory products. But supporters argued California can make a difference by serving as a model for other states.

The measure includes exemptions for musical instruments made before 1975 that are less than 20 percent ivory; antiques over 100 years old that are less than 5 percent ivory; and sales or imports of ivory for educational or scientific purposes if the item was acquired before 1991.

San Francisco and Los Angeles make up two of the country's top three hubs for ivory sales. New York, which wildlife officials call the country's biggest ivory market, banned the sale of most elephant ivory, mammoth tusks and rhinoceros horns last year.

On Saturday, the governor vetoed separate legislation by Sen. Ricardo Lara, D-Bell Gardens, to ban the use of bullhooks to guide and discipline elephants starting in 2018. That bill is SB716.