That's the title of the latest article by Ralph Manns over on the BFHP. You can link to the article here. If you've fished around Indiana much, you've probably run into this phenomenon a time or two. It seems more prevalent on certain lakes than others. This past year I noticed one lake in particular that had a very high incidence of bass with these black blotches. They look almost like fingerprints on a basses body. Sometimes on the tail or fins and other times on the mouth. I actually have pictures showing the condition on bass here in Indiana going back to the late 80's [pic (upper left) of me with a bass from L. Lemon from around 1990 - click to enlarge], so it's certainly not a new occurrence. If you're still not certain of what I'm referring to, take a look at this blurb from the TN Wildlife Resource Agency. They refer to the anomaly as hyperpigmented melanosis. The fish in the picture has a more extreme case.
Ralph makes some interesting observations, though I'm not certain I agree completely with them. That's the inherent problem with anecdotal evidence. I'll be very curious to see what Auburn U. comes up with in their studies. I was noticing this blotching on bass enough last year that I made a call to our state pathology lab. It is located up at Purdue University and is where all fish forensic studies for the state take place. I was able to speak with one of the lead pathologists at the lab concerning the blotching and he mentioned 3 possibilities. One was the trematode parasite Digene. For more information than you probably care to have on the Digene life cycle and trematodes in general, see this West Virgina University PowerPoint presentation.
The second suggestion was some type of chemical or environmental contamination. This would be hard to track down though without extensive and expensive water quality parameter testing. Ironically enough this particular lake was one of only 9 in Indiana to be selected at random by the EPA for its 5-year revolving National water testing program. They took samples early last summer and I'm hoping to be able to get my hands on the full report sometime later this year or next.
The final possibility suggested was 'unknown', that being we simply don't know what is causing the blotching. Not a very satisfying answer but certainly a practical one. They said I was more than welcome to bring a bass or two harboring this blotching to their labs for testing if I'd like. Unfortunately the testing runs several hundred dollars, so I chose to hold off on pursuing that avenue. I think this year I'm going to try and take detailed notes from this lake. I'll document total fish caught, number showing the blotching, size and weight of bass with the blotching as well as a general location of the blotching for each fish. It might give some clues to the mystery, particularly if this is a seasonal occurence which might be more in line with the Digene theory. And if I stumble across an extra couple hundred dollars, I may even just run some fish up to the path lab in West Lafayette.
Fishing for Food
There is a very interesting article in the most recent issue of "Fisheries" magazine. It's a human dimensions article dealing with one of fishings sociological issues, that of subsistence fishermen. The article is entitled Searching for Subsistence: In the Field in Pusuit of an Elusive Concept in Small-scale Fisheries. It can be found midway through the publication on page 592 (page 20 of 52). It is a decent sized download at just over 5MB in case you have dial-up. It examines some of the definitions, stereotypes and self-descriptions of subsistence anglers and starts laying the foundation for future research. I found it particularly interesting because of the many comments and observations I hear from other anglers of subsistence fishermen in our neck of the woods, most notably from bank anglers and river anglers chasing smallmouth bass. I think it will be particularly interesting once studies progress enough to start dealing with the management implications associated with the perceived problem.
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