The film explores environmental issues affecting oceans, including plastic pollution, ghost nets and overfishing,[2] and argues that commercial fisheries are the main driver of marine ecosystem destruction.

[15][16] Seaspiracy also prompted responses from other environmental organisations, academics and seafood industry groups, and several media outlets fact-checked certain statements in the film.

[17] The film's settings are global, including the Taiji dolphin drive hunt in southern Japan, whaling in the Faroe Islands, Thai and Chinese fish markets, coastal West Africa, and salmon aquaculture farms in Scotland.

At various moments, Tabrizi and his crew appear to face imminent peril from local authorities or corrupt fishing industry players; some of the action is presented through hidden camera techniques, and animation is used to depict scenes of violence.

The film suggests that aquaculture is untenable due to the problem of feed for farmed fish and the prevalence of disease and coastal degradation.

[20] Seaspiracy received production support and initial funding by British renewable energy entrepreneur Dale Vince after meeting Cowspiracy director Kip Anderson in 2016.

[23][24] The documentary was one of the top ten most watched films on Netflix in several countries in the week of its release and generated significant traction on social media.

[25] Natalia Winkelman of The New York Times gave a mixed-to-negative review, concluding that the film "does present some pieces of reporting — including an inquiry into dolphin-safe tuna can labels — that are surprising and memorable.

But even the film's notable points seem to emerge only briefly before sinking beneath the surface, lost in a sea of murky conspiratorial thinking.

"[29] Common Sense Media gave the film a 4 out of 5 stars and 15+ rating, calling it "tough but necessary viewing" and "backed with evidence from journalists, authors, marine biologists, oceanographers, frontline activists, and industry insiders".

[38][39] A representative of Fauna and Flora International wrote that the film has "bitterly divided the environmental community" and described its interpretation of scientific studies as "highly problematic and often woefully misleading."

[40] Charles Clover of Blue Marine Foundation and author of the book The End of the Line criticised the film's scientific accuracy, saying "there are a few jaw-dropping factual errors" such as its framing of whale strandings.

He said such strandings have a variety of causes other than plastic pollution alone, and accused Seaspiracy of deriving its narrative from previous documentaries, such as the film adaptation of his book.

Nonetheless, he praised its communication of marine fisheries and conservation issues to a new audience, stating "[t]he problem of overfishing is immense, global, remote, horrifying and it is really hard to get people to focus on.

[12][22] A reviewer in Hakai Magazine wrote, "had Tabrizi looked at any of these issues in greater depth, he'd have found that journalists have been covering these sorts of stories for years and have not glossed over the nuance.

[16] Bryce Stewart, a University of York marine ecologist and fisheries biologist, criticised the film's scientific accuracy and neutrality, calling it "the worst kind of journalism" and questioning its lack of coverage of the impacts of climate change on oceans.

However, he said it also "undermines [its message] with an avalanche of falsehoods", citing its coverage of marine debris, bycatch and sustainable fishing, as well as "blames the ocean conservation community, i.e., the very NGOs trying to fix things, rather than the industrial companies actually causing the problem".

[46] The Marine Stewardship Council, Earth Island Institute and Plastic Pollution Coalition disputed their negative portrayal in the documentary, and suggested that their representatives' comments were cherry-picked.

While acknowledging some inaccuracies, Monbiot says that the main point of the film is correct: the fishing industry is the greatest cause of the ecological destruction of the oceans, and cites the 2019 IPBES report as evidence to back this assertion.

The fact check cites Jenna Jambeck, the author of the coastline study, saying "no-one really knows how much of it is straws, but experts agree that it is certainly a lot less than dumped fishing gear."

The author of the latter study on the Great Pacific garbage patch, is quoted as saying "[fishing gear] fragments much more slowly and is also very buoyant; prime candidates to hang around in the GPGP", as opposed to thinner plastics like straws and bags, which disintegrate and sink.

[53] This is in response to Mark Palmer, associate director of the International Marine Mammal Project of the Earth Island Institute, who says on camera that "dolphin safe" tuna cannot be guaranteed, and that observers can be bribed.

[15][48] Senior fisheries scientist Sara McDonald of the Monterey Bay Aquarium was quoted by Newsweek in a Seaspiracy fact check article: "The U.S. dolphin-safe program has been very effective.