Ameron International Corp. said its first-quarter earnings dropped 72 percent, largely due to lower sales in the slower economy. The industrial products maker also disputed an activist shareholder’s criticisms about its executive compensation.

The Pasadena company, which makes concrete and steel water pipes and fiberglass pipes for the oil and chemical industries, late Tuesday reported net income of $1.08 million (12 cents per share) compared with $3.82 million (41 cents) a year earlier. Sales fell 25 percent to $109 million.

Analysts surveyed by Thomson Reuters expected the company to report per-share earnings 56 cents on revenue of nearly $129 million.

Barington Capital Group, a New York hedge fund that has accumulated 3.7 percent of Ameron shares, earlier this week sent the company a five-page letter criticizing management. The letter detailed actions that the company should take to boost its “significantly undervalued” stock, including steep pay cuts for top executives such as Chief Executive James Marlen.

Marlen took home $39 million in total compensation between 2004 and 2008, compared with an average of less than $22 million for CEOs of 12 peer companies, according to Barington Chairman James Mitarotonda, who has unsuccessfully sought a seat on Ameron’s board.

The company on Wednesday released a response from Marlen, who wrote that “while we wholeheartedly agree with you that Ameron’s stock is undervalued . . . we disagree with many of your theories as to why Ameron is undervalued.”

But Marlen also said he looked forward to talking with Barington about its issues at today’s annual shareholders meeting.

Shares were down $3.93, or nearly 6 percent, to $63.46 in midday trading on the New York Stock Exchange