Adam, T.C.; Ruttenberg, B.I.; Roycroft, M.V.; Burkepile, D.E.

Impacts of fishing on parrotfish grazing in St. Croix - A case study on the ecological impacts of fishery management actions: Final Report

2020

NOAA; NMFS; Southeast Fisheries Science Center

"This report summarizes information from a three year study to evaluate the impacts of fishing on parrotfish grazing in St. Croix, U. S. Virgin Islands. The largest parrotfish fishery in the U. S. Caribbean is located on St. Croix. For many years, commercial landings of parrotfishes on St. Croix had approached or exceeded 400,000 lbs. annually, with parrotfishes accounting for nearly one third of landings. There is concern that these high levels of parrotfish fishing in St. Croix may negatively impact coral reef ecosystems through a reduction in parrotfish grazing, resulting in an increase in algae that can inhibit the recruitment, growth, and survivorship of reefbuilding corals. In order to quantify potential impacts of the parrotfish fishery on coral reefs around St. Croix, we combined data on parrotfish foraging behavior with data sets on parrotfish abundance and size-structure from fishery-dependent and fishery-independent monitoring efforts. The project had three interlinked components. First, we conducted behavioral observations of parrotfishes on coral reefs in St. Croix to parameterize species- and size-specific models of parrotfish grazing. Next, we applied these species- and size-specific models of parrotfish grazing to NOAA monitoring data sets on the abundance and size-structure of fishes to understand how the grazing impacts of parrotfishes vary spatially around St. Croix. Finally, we synthesized data on parrotfish populations, parrotfish foraging behavior, and the parrotfish fishery to predict the ecosystem-level impacts of the fishery in St Croix. Our results suggest strong fishing impacts on parrotfish populations and ecosystem level processes, and we conclude with a series of management recommendations for ways to reduce negative impacts of parrotfish fisheries on reef ecosystems in St. Croix."

FY20; CRCP Project ID: 30061; Project Title: Impacts of fishing on parrotfish grazing in St. Croix -A case study on the ecological impacts of fishery management actions; Principal Investigator: Jay Grove