The Part of the Fish With the Most PFAS Is Also the Part Almost Nobody Eats

PFAS, the so-called forever chemicals, keep turning up in fish tissue studies, and it's easy to read those headlines and assume every fillet is a risk. A new study out of northern New Mexico tested PFAS in fish you catch, common carp, catfish, smallmouth bass, walleye, northern pike, white crappie, and white sucker, and the actual pattern in the data is more specific than the headlines suggest. The chemicals concentrated hardest in fish liver. Muscle, the part you actually fillet and eat, came back consistently lower.

The Study

Researchers collected 40 fish total, from Abiquiu Reservoir, Cochiti Reservoir, and five sites along the Rio Grande, using gillnets, hoop nets, and rod-and-reel over the summer of 2023. They tested both muscle and liver tissue from each fish for 39 different PFAS compounds. This is the kind of unglamorous, direct sampling work that doesn't make headlines on its own, forty fish, three water bodies, a lab running compound panels, but it's exactly the data you'd want before anyone tells you whether your catch is safe to eat.

Where the PFAS in Fish You Catch Actually Concentrates

Here's the part worth sitting with. PFAS showed up in nearly every fish tested, roughly 37 of 40 fish had detectable PFAS in muscle tissue, and all 38 liver samples the researchers were able to collect came back positive. But the concentrations weren't close. Average PFOS, the compound found at the highest concentrations, measured 41.21 nanograms per gram in liver tissue versus 1.31 nanograms per gram in muscle, a statistically significant gap. Most liver samples, 35 of 38, came back above the 10 ng/g threshold used in published fish consumption advisories. Muscle told a different story entirely. As the researchers put it plainly, "all muscle samples fell below these guidelines." Nobody's frying up fish liver for dinner. The tissue anglers actually eat was the tissue where this study found the least contamination.

What Else They Found

A few other patterns showed up. Rio Grande muscle samples mostly measured under 1 ng/g, with one exception, a channel catfish that came in at 3.28 ng/g. In the reservoirs, PFOS in muscle ranged from about 0.4 to 4.2 ng/g, averaging under 2 ng/g. Bottom-feeding fish carried higher PFOS in their liver than predatory fish like pike and bass, though that trend reversed in the muscle tissue. The researchers also found a correlation, not a stronger claim than that, between a fish's position in the food chain and its concentration of one specific compound, PFDA, describing the evidence as moderate. And zoomed out, the fish in this study averaged lower total PFAS than the reported U.S. average, with about 70 percent falling under the European Union's stricter combined threshold for four commonly regulated PFAS compounds.

The Catch

The researchers are upfront about what this study doesn't nail down. They didn't record the age or sex of the fish they sampled, both of which could shift PFAS levels on their own. Water levels ran unusually high in 2023, and without separate water-sample data, they can't say for certain whether that affected what showed up in the fish. And they're clear that this study documents what's present, not whether it's dangerous. The authors say plainly that more research is needed before anyone can say whether the levels found here pose a real risk to fish or the people eating them. This is one river system and two reservoirs in New Mexico, not a verdict on PFAS in fish everywhere.

Should You Worry About Eating What You Catch

I've never fished New Mexico, so I can't tell you anything about Abiquiu or Cochiti Reservoir from experience. But I've eaten a lot of walleye. Multiple trips to Canada with my uncle, eating walleye almost every meal for a week at a time, and that's exactly the kind of high-frequency consumption where accumulated contaminants would matter most if they were going to. Reading this study didn't scare me off that tradition, but it did make me want to actually know what's in the water I'm fishing, not just assume. Most states publish their own fish consumption advisories by species and water body, and they exist for exactly this reason. My honest takeaway, and this is my read, not the study's, is that trimming the fillet and skipping the organs was already standard practice for most anglers I know, and this is a real, specific reason that habit matters. This is one study on one river system, worth knowing about, not worth panicking over.

Citation

Clements, J., Stanek, J., Conrad, C., Celmer, J., Mora, H., Jones, Z., Gallegos, K., Gadek, C., & Gaukler, S. (2025). Per- and polyfluoroalkyl substances (PFAS) in fish collected from the Rio Grande and reservoirs in northern New Mexico. PLOS ONE, 20(11), e0336856. https://doi.org/10.1371/journal.pone.0336856