AUSTIN, TEX. -- Total earnings for U.S. savings and loan institutions fell 80 percent for the first quarter of 1987, compared with the same period last year, reflecting deep problems in the S&L industry in the Southwest, according to a banking industry consulting company.

Savings and loan associations in 35 states reported declines in earnings, but the greatest problems were focused in Texas and the Southwest. Repossessed assets as a percent of total assets came to 1.28 percent, up from 1.11 percent during the previous quarter, the report released Tuesday said.

Of the $2 billion increase in repossessed assets, $1.1 billion came from Texas thrifts.

"The savings and loan industry today presents a study in contrasts that is relected in the performance of individual thrifts," said Alex Sheshunoff, president of Sheshunoff and Co.

"On one hand, there are many conservative institutions that have performed well because they never strayed far from the thrifts' traditional role of providing home mortgages. At the other extreme, there are what I call 'renegade' thrifts that have clearly operated unsoundly and in some cases outside of the law," he said.

Nationwide, combined earnings for the first three months of the year for all 3,228 federally insured savings and loan associations came to $340.1 million, compared with earnings of $1.7 billion for the same period last year. Annualized return on assets came to 0.11 percent, down from 0.61 percent reported for the first quarter of 1986.

"A major portion of the industry's problems can be traced to fewer than 300 savings and loans," Sheshunoff said.

He said that the thrift industry performed reasonably well if results from the Southwestern states were not included. Savings and loan associations nationwide earned $1.6 billion if the $1.2 billion loss in the Southwest is excluded