Image source: SeaWorld Entertainment.

What: Shares of SeaWorld Entertainment (SEAS 0.51%) fell more than 11% Thursday after the company announced a wider-than-expected fourth-quarter 2015 loss and made a surprising admission.

So what: Quarterly revenue climbed 1.3% year over year to $267.9 million, while adjusted earnings before interest, taxes, depreciation, and amortization fell 5.2% to $47.3 million. That translated to an adjusted net loss of $9.6 million, or $0.11 per share, narrowed from a net loss of $17.8 million, or $0.20 per share in last year's fourth quarter. Analysts, on average, were anticipating roughly the same revenue to result in a slightly narrower adjusted net loss of $0.10 per share.

Meanwhile, SeaWorld reported Q4 attendance of 4.41 million, up from 4.37 million in last year's fourth quarter. Noting this increase as well as the fact that adjusted EBITDA for the year (at $361.1 million) fell within their latest guidance, CEO Joel Manby said, "Our near term priorities remain clear: execute our strategy with a focus on operational excellence and deliver the consistent and sustainable financial performance expected of our great organization."

During the subsequent conference call, however, management described attendance as "soft" so far in the first quarter. In addition, Manby admitted SeaWorld employees had been sent to pose as animal rights activists to spy on groups like PETA, effectively confirming allegations of as much brought by the group in a lawsuit last year. More specifically, Manby stated SeaWorld's board "directed management to end the practice in which certain employees posed as animal rights activists," while at the same time insisting the practice was "undertaken in connection with efforts to maintain the safety and security of employees, customers, and animals in the face of credible threats."

Now what: Regardless of SeaWorld's intentions, the admission of spying on animal rights groups will almost certainly bring more bad press for a company still struggling to recover from negative publicity surrounding its alleged mistreatment of animals, notably as depicted in the 2013 documentary Blackfish. Combined with its slight earnings miss and light attendance in the current quarter, it's no surprise SeaWorld investors are taking a step back today.