Ecological consequences and population changes from intensive fishing of a shallow-water mollusc, Strombus gigas: A site study of Parque Nacional del Este, Dominican Republic

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Kathleen Sullivan-Sealey - Committee Chair


This study was undertaken to determine the effects of fishing pressure on a Strombus gigas population in a shallow water marine lagoon (Canal de Catuano), southeastern Hispaniola and to examine the possibilities of restoring this important fishery resource after a long history of human impacts. The history of S. gigas fishing for the area was studied through the excavation of several shell middens to detect changes in fishing pressure. Concurrently, an extant S. gigas population was surveyed to assess the current status and the short-term trend for the population in the study area. Lastly, an enclosure experiment was carried out over ten months under natural conditions to determine the effects of changes in S. gigas density on its habitat and the implications such changes may have for future management and restoration efforts.I found that fishing pressure for Strombus gigas changed dramatically over the past 6,000 years. Shell measurements obtained from midden excavations showed that the mean shell length of S. gigas changed since the earliest available record of human impacts. However, pulses in fishing pressure since human impacts began have allowed the recovery of the still highly impacted juvenile population in the shallow waters of Parque Nacional del Este (PNE). Juvenile S. gigas density was estimated at 30.63 individuals per ha during 2000, but mean density declined to 1.40 individuals per ha by 2001. The most likely cause of this decline was fishing. Population estimates for juvenile S. gigas were 41,980 individuals during 2000, but only 1,919 individuals by 2001. Adult S. gigas density was estimated at 0.03 individuals per ha in 2000, but only 0.08 individuals per ha by 2001. Population estimates for adult S. gigas were only 47 individuals during 2000 and 110 individuals in 2001. Experimental studies indicated that high S. gigas densities directly impacted benthic vegetation and herbivory competition on soft-sediment communities, causing declines in seagrass shoot density and blade length and changes in seagrass coverage from dense to moderate cover. (Abstract shortened by UMI.)


Biology, Ecology; Agriculture, Fisheries and Aquaculture

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