"The threats that have caused marbled murrelets to decline throughout their range have not been remedied," said Beissinger. "Coastal old growth forests will require 50 to100 years of restoration, and prey resources haven't recovered from the sardine fisheries collapse in the mid-20th century. Other prey items that the murrelets feed upon, including rockfish, have had to have seasonal closures because of heavy harvest for commercial markets. Similarly, the anchovy fishery in central California has declined by 75 percent since 1974."
The study results support the need for fisheries to be managed to address their broader impacts on the ecosystem, the researchers said. "Traditionally, decisions on how much to harvest were made by calculating the impact of fishing on a single species, or by determining how much can be fished in order for the population to rebound in subsequent years," said Becker. "Now, more people are taking an ecosystem approach, considering how harvesting one species will impact other species that rely upon it. However, so little is known about the diet of the murrelet that a study like this is important in informing fishery management decisions."
"Our study also highlights the need to consider locations that improve the production of seabird prey in the ongoing process to determine where to place marine protected areas along the California coast in order to restore marine food webs and conserve seabirds," Beissinger added.
The researchers are conducting additional studies using feathers from a wider range of seabirds and from a greater selection of time periods to get a clearer picture of impacts of oceanic conditions and fishing pressure throughout the past century.'"/>