COATES, K.A*; JANTZEN-MARSON, C.; MADEIROS, J.L.; MEYER, E.; Bermuda Biological Station; Bermuda Biological Station and Bermuda Department of Conservation; Bermuda Department of Conservation; Bermuda Biological Station and Rutgers University, Camden, NJ: West Indian topshell, Cittarium pica, reintroduction project in Bermuda: Current status
The West Indian topshell, Cittarium pica, (Trochidae, Archaeogastropoda), a large snail found on the rocky intertidal shore, may have been abundant in Bermuda up to the early 1800’s. However, Abbott, among others, thinks it probably disappeared from the Bermuda shoreline during the most recent glacial low water stages. There have been repeated attempts to reintroduce this snail to Bermuda since 1901, and most recently in 1982. None of the reintroductions were thought to have been successful until about 1989. Since 1989 C. pica has been a protected species in Bermuda. Extensive surveys of the snail in Bermuda were begun in 2000 to determine its abundance, distribution, population structure and dynamics. The snails are now found along the south, east, and west shores of Bermuda. Significant settlement, evidenced by numerous individuals with 2-6mm diameter shells occurs throughout the summer months, from June to at least September, suggesting most spawning occurs after February. Illegal harvesting incidents indicate snails with shell diameters less than 45mm are not reproductive. Thus, snails become reproductive in their third year. Growth rates of snails bigger than 40-50 mm are apparently lower and more variable than in the younger snails, and the largest snails found were 130mm. More specific data on reproductive periods, spawning, settlement, and growth rates are being generated. These data together may be used to determine the feasibility or even desirability of limited harvesting of the snails. A concern about this (re)introduced species is that it might assume the characteristics of an invasive population and negatively impact the diversity of the rocky intertidal shore.
