MIAMI — In an era of prolonged low interest rates, owners of captive insurers should consider alternative investment strategies to increase returns, a panel of experts said.

By investing in structured financial vehicles in addition to traditional captive investments, owners potentially can achieve significantly higher investment yields and still guarantee return of the principal invested, they say.

When captive insurers became popular in the 1970s and 1980s, interest rates were so high that owners could obtain significant investment income from traditional safe investments, such as short-term bonds and other fixed-interest investments, said Arthur G. Koritzinsky, managing director, captive solutions at Marsh USA Inc.

Since the 2008 financial crisis, however, interest rates have remained in the low single digits, which has led to significantly lower returns from the conservative investment vehicles favored by captive owners, he said Friday during a session at the World Captive Forum, which is sponsored by Business Insurance, in Miami.

But alternative investments such as structured term deposits give captive owners a chance to make better returns, Mr. Koritzinsky said.

“We need to make sure there’s liquidity there because claims have to be paid, that there’s security there — you don’t want the captive picking up unnecessary credit risk — and you need get a return,” he said.

A typical structured term deposit would run for a five-year term guaranteeing return of the principal and the higher of 1% a year or investment returns from an agreed credit index, said Philippe Combescot, managing director, financial institutions at BNP Paribas Securities Corp. in New York.

The indices used can range from the S&P500 to Morningstar Stockpickers to indices tracking more diverse asset classes and regions, he said.

Captive owners can draw down a line of credit against the deposits if they need to pay a significant claim; however, they have to be comfortable with the credit risk of the financial institution that provides the structured term deposit accounts before making the investment, Mr. Combescot said.

“If you can get comfortable with the credit risk, you can do no worse than 1% a year,” Mr. Koritzinsky of Marsh said.