Appendix I: Agenda
Appendix II: List of Participants
Appendix III: List of Planned Publications
Production of Fish and Benthos on Georges Bank
Collie, J.1, A. DeLong1, and R. Bell1
1Graduate School of Oceanography, University of Rhode
Island, Narragansett, RI 02882
The objective of this study is to elucidate the benthic invertebrate
and fish components of the Georges Bank energy budget. Available
estimates of benthic production are on the order of 100 kcal m-2
yr-1, of which 60% is suspension feeders and 40% deposit feeders.
However, there is considerable temporal and spatial variation, some
of which is attributable to fishing activity. On gravel habitats on
the northern edge of Georges Bank, benthic production is
approximately four times higher in unfished areas than in fished
areas. Bottom fishing therefore has indirect effects on energy
flow, beyond the direct removals of target species. Preliminary
estimates have been made of energy flow through the Georges Bank
food web. The microbial loop is more important than was previously
thought, with 80% of the production derived from recycled nitrogen.
The upper components of the food web are supported by zooplankton
and benthic production. Based on our preliminary estimates, the
upper trophic levels do not appear to be food limited, especially
during periods of depleted fish stocks. We have constructed
biomass-dynamics models of the three trophic guilds of fish:
benthivores, planktivores, and piscivores. Decadal shifts in the
abundance of these trophic guilds can be simulated with bottom-up
forcing and/or by altering the fishing mortality regime. These
models will be refined to fit the actual biomass trajectories of the
three fish guilds.
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