Ecological Modeling of American Lobster ( Homarus americanus ) Population in the Gulf of Maine
The Gulf of Maine (GOM) ecosystem has experienced large changes over the last several decades, switching from a groundfish species dominated system to a system dominated by crustacean species such as the American lobster and crabs. Several hypotheses have been developed to explain such a switch, ran...
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DigitalCommons@UMaine
2005
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/1526 https://digitalcommons.library.umaine.edu/context/etd/article/2550/viewcontent/ZhangY2005.pdf |
| Summary: | The Gulf of Maine (GOM) ecosystem has experienced large changes over the last several decades, switching from a groundfish species dominated system to a system dominated by crustacean species such as the American lobster and crabs. Several hypotheses have been developed to explain such a switch, ranging from trophic interactions between groundfish and crustacean species to increased food availability to crustacean species due to discarded baits in the lobster fishery. The objective of my study is to develop a lobster ecosystem model to evaluate the dynamics of GOM lobster ecosystem. I developed a mass-balance ecosystem model separately for the two time periods (1980s and 1990s) using Ecopath with Ecosim (EwE). The model has twenty-four function-groups including lobster, its key predator and prey species, and other important groups in the ecosystem such as zooplankton, phytoplankton and detritus. The input data were obtained from published papers and reports. Using the models developed, I conducted a comparative analysis of trophic interactions and community structure of the GOM American lobster ecosystem for the mid-1980s and mid-1990s. I also simulated ecosystem dynamics in the GOM from 1985 to 1997 using Ecosim, evaluated the interactions of population dynamics of Atlantic cod and American lobster, and predicted the possible response of the lobster population with respect to the possible recovery of Atlantic cod stock in the GOM. The study shows that the Ecopath model, which snapshots the ecosystem in a given time, and Ecosim model, which tracks the long term dynamics of ecosystem, can well simulate the lobster ecosystem in the GOM. The trophic structures of the ecosystem in the mid-1980s are different from those in the mid-1990s with a decrease in top predator biomass and an increase in lower trophic-level organism biomass. The derived key ecosystem parameters suggest that the mid-1990s ecosystem tends to be more mature than the mid-1980s ecosystem. The results also suggest that there is a negative ... |
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