Log on line note

On July 6 during a beach walk on the west barrier bar of Fair Haven Bay, a youngster called my attention to an oddity. “Look at my pet fly” he said. He has no wings”. Sure enough the fly on his arm was flightless. A bit of looking around showed it was obvious the fly had recently pupated from a fish carcass. There were dozens of dead fish lying around, mostly bass, a few other species on the beach that day. What had killed them was the subject of considerable speculation, most people opting for water temperature change with a shrug of the shoulders.

I was thinking to myself, well, I don’t know if water temperature change (which had supposedly occurred on July 5 according to DEC) alone was an adequate explanation. Maybe something else is going on too. A number of the dead fish were obviously several days old as they had been colonized by maggots and the dark capsules of fly pupae were evident in the sand around at least one dead perch. Meantime, the kid and I searched and soon found many more wingless flies. There appeared to be two species of flies present, shiny bodied “blue bottle” blow fly types and a more ordinary looking housefly sized flesh fly species. The blue bottles generally had one wing, the flesh flies no wings. We counted at least 20 such flies all in a few square yards near the jetty. I wondered if the deformed flies were the product of a single carcass as we had not noticed ( nor looked for them) anywhere else on the beach. The internet says it takes about 8 days (depending on temperatures) for blue bottle flies to emerge from a dead fish, so presumably the fish washed up around June 28-29 .

I sent off an e mail to the Lake Ontario science community via Jack Manno and in turn got the suggestion that indeed such a fly “birth defect” as it were could be caused by a chemical present in the environment in a fairly high concentration. For those not aware, the adult bass is a predator that eats fish, crayfish frogs and other creatures. This puts the bass up fairly high on the food chain and likely to concentrate any toxins present. Many years ago I attended a conference on toxins in the Great Lakes that included a presentation on toxin levels in blowfish larvae found on a salmon carcass that were in the 100 plus ppm range. So toxic substances are definitely a suspect here. We’re waiting for a toxicologist to respond. If we get a response we’ll add it to this note.

Meantime, join the log editor in being a shoreline steward and monitor. If you notice any odd animals, mutant maggots or wingless flies tell us when and where you saw it/them send it in to susan@silverwaters.com and we’ll post it here.