Mark Bethke (Ferreter) wrote, >For those out there that say the numbers are not declining , whatever happened to terebra taurinum which at one time was common throughout florida, strombus gallus that was as common as alatus mitra florida , you never see these anymore, or cymatium parthenopeum or cittarium pica both at one time were as common as mud, futhermore not one of these species is commercially havested , the numbers were whiped out by collectors who had not restrictions . That's quite an accusation, and I'd like to ask the old-timers some questions about it. First, is the decline real? Second, are collectors definitely the cause, or change of habitat as the area was developed? There are a lot more people on Sanibel Island (Florida) now. Where does their sewage go? How has the Sanibel environment changed in the last 30 years or so? It's hard to tell why a species declines in any given case. In some cases, the decline is sudden and the species is slow to recover. This can be due to unusually cold weather, storms, disease, introduction of a new predator or parasite, oil spills, etc. ("mass mortality"). In others, the species declines over a period of time, perhaps due to overfishing, overcollecting the breeding adults, or to a gradual change in habitat (dredging, trawling, lower influx of fresh water due to dams upstream, pollution, etc.). The Pleistocene extinctions of large animals were probably due to overhunting. By analogy, if only the largest and most attractive Sanibel mollusks are in decline, then collecting may well be the cause of their decline. Is this the case here? Don't be quick to accuse. People have great confidence in themselves and tend to think that they are responsible for changes in the ecosystem. This is very often true, starting probably with the invention of fire and weapons. But people sometimes blame themselves unfairly. Shallow-water marine systems tend to have extreme, natural fluctuations in the populations of plants and animals, even without people's interference. Anecdotal data from collectors who settled on sparsely populated coasts suggest this, and the paleontologic record proves it. It would be remarkable if Sanibel molluscan populations were absolutely constant from year to year. Well, I've never visited Sanibel, so I don't have a clue. To those who have the experience to answer a very complex question: How have Sanibel and its mollusks changed over the years? Andrew K. Rindsberg Geological Survey of Alabama Tuscaloosa, Alabama, USA P.S. Of the species that Mark listed, Cittarium pica is eaten in the Bahamas as a supposed aphrodisiac--as discussed in a previous thread. This species is therefore one that may well have been overharvested by Man, but not necessarily by horny shell collectors. P.P.S. To North Americans: Have a pleasant, thoughtful, and thoroughly enjoyable holiday this Thanksgiving.