Nautica Enterprises Inc reported an 11 per cent increase in net sales to $135.2 million from $121.3 million in the first quarter of last year. Net earnings rose slightly to $3.2 million compared with $3.1 million in the same period last year. Diluted earnings per share were $0.09, comparable to the first quarter of the prior year due primarily to the company's investments in new businesses and its infrastructure.