BassBlaster

Science: Save a Bass, Eat a Flounder

Keep too many largemouth and you might start looking like this guy.

Keeping with the Delta theme this week due to the Bassmaster Classic, some more science news, this time giving you another good reason to practice catch and release. Lets face it, you don’t want to show up at the ramp looking like the basser on the left. Chances are you’d be left standing on the bank no matter how cool your tourney jersey. How could this happen, and what does KVD know that ties in with this story?

A recently published study on the mercury levels in bass and flounder on the Mobile-Tensaw Delta shed some interesting light on what is going on. First though, a little mercury history lesson. The Mad Hatter from the ‘Alice in Wonderland’ novel is based on an actual disease believed to have been prevalent in the hat making industry during the 1800’s. “Mad Hatter’s Disease” stems from the bio-accumulation of mercury in hat makers bodies from using a mercury solution to turn fur into felt. Typical symptoms resulting from mercury poisoning include trembling and loss of coordination, slurred speech, loosening of teeth, and memory loss. But I digress…back to the fishing.

The study out of Auburn University* found a couple interesting things. One was that the mercury contamination in largemouth bass matched a salinity gradient in the Delta. In other words, largemouth bass in the saltier southern part of the Delta had lower average mercury levels than similar bass in the more northern freshwater areas. The further north they went, and the more the salt levels in the water decreased, the higher the average mercury levels.

Interestingly, when they tested flounder along a similar gradient, they didn’t see this pattern. In fact, across the board, flounder had much lower levels of mercury regardless of location when compared to the largemouth bass. Why might this be so? One theory proposed was due to the difference in diets.

Diet analysis of largemouth bass found that the bass in the less saltier northern sections ate more vertebrate prey such as bluegills, while their cohorts to the south in the saltier sections ate more invertebrates (blue crabs, shrimp). Analyzing these prey species found that the bluegill did, in fact, have higher levels of mercury in their tissues than did the blue crab. This finding provides some key insights into what might be behind the difference in mercury patterns.

As relates to human health, the authors conclude that “…largemouth bass that are harvested under current practices have a high probability of exceeding the USEPA advisory level of 0.3 lg/g”, and that “ …a 356-mm (i.e., 14-in) minimum length limit for largemouth bass would not be recommended. In fact, from a public health perspective, no reasonable minimum length limit (e.g., 305 mm [12 in] or 254 mm [10 in]) can be recommended.”

So the take home message here; if you fish in the Delta and want to keep some fresh fillets for the table, you’d be wise to err on the side of caution and release every bass that you catch, and instead toss a few flounder into the livewell without concern.

And here’s that bonus bass tip from KVD himself on how to match those blue crabs when chasing those green fish down in the Delta: “I mainly stick to fishing Strike King Elite double rattle black/blue/purple jigs with powder-blue Zoom super-chunks, which resembled the crabs…”

*Mercury Concentration in Two Estuarine Fish Populations across a Seasonal Salinity Gradient. Troy M. Farmer, Russell A. Wright, and Dennis R. DeVries. Transactions of the American Fisheries Society 139:1896–1912, 2010.

1 Comment

1 Comment

  1. Jason

    February 14, 2011 at 8:51 am

    Not to mention that a flounder will blow a largie away when it comes to table fare [in my not-so-humble opinion].

    Give me a big ol’ saddle blanket stuffed with crawfish and lump crabmeat over one of those funky green fish any day!

    Mmmm… if this don’t make you want to slap yo’ momma’, your taste buds ain’t calibrated right.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Gitcha Bassin' Fix

To Top