Source: Blackfish. 

SeaWorld (SEAS 2.01%) has suffered another quarterly attendance drop, according to new SEC documents. The aquatic amusement park had a controversial year thanks to Blackfish -- a documentary film that follows an orca that has played a role in two trainer deaths and that continues to reside at a SeaWorld park. However, has Blackfish driven down SeaWorld's attendance numbers on its own or is the falling attendance an industry trend also felt by Walt Disney and Cedar Fair

The latest quarterly attendance drop appeared in a filing that described a planned share buyback. The news came as the latest in a long string of SeaWorld-related stories that included several high-profile musicians canceling scheduled gigs at the parks. SeaWorld was also caught manipulating an online poll that asked whether Blackfish would keep visitors away. 

So SeaWorld has shown fear in the face of Blackfish. However, how much has attendance dropped since the first release of the film in summer 2012? 

Attendance numbers 
SeaWorld recently filed a registration statement to announce the planned repurchase of 1.75 million shares. Included in the statement were preliminary attendance numbers for the quarter ending March 31. SeaWorld expects to report a total of about 3 million guests, which would amount to around a 16% decrease from the 3.5 million guests it saw in the first quarter of 2013.

How do those numbers stack up to attendance pre-Blackfish

SeaWorld's attendance has seasonality built into it because several of the parks are only open for part of the year. So the second and third quarter should show the strongest attendance numbers. Attendance in the second quarter of 2013 declined nearly 10% year-over-year and the third showed a decline of nearly 4%.

The second-quarter drop came before the release of Blackfish, so the lowered attendance likely stemmed from a combination of poor weather and ticket price increases. However, some of the third-quarter drop could have come from the Blackfish backlash. 

Competitor comparison 
Regardless of why SeaWorld's attendance has slipped, the numbers don't match up with the overall trends of the industry. Walt Disney World in Florida welcomed record numbers last summer. Cedar Fair reported that its Cedar Point park had flat attendance in the third quarter, year over year, but that jumped to 2% growth with the omission of the two water parks that the company sold in the period.  

SeaWorld's fourth-quarter attendance dropped 1.4% to 4.5 million. Cedar Fair had 2% growth in comparable-park attendance for that quarter. 

What to watch this year 
Investors should watch SeaWorld's attendance numbers in the second and third quarter of this year for signs of further weakness. Blackfish has continued to gain new viewers through word of mouth and a continued presence on Netflix. I've encountered several people who purposefully put off watching the film until their families' SeaWorld season passes expired -- and now have no plans for renewal.

Foolish final thoughts 
SeaWorld definitely suffered a public-relations black eye thanks to Blackfish. However, it's hard to tell what portion of the attendance drop came as a response to the film. Further weakness during next year's seasonal quarters will mean that SeaWorld has a serious attendance problem on its hands -- regardless of the reason.