Aquatic Ecosystems and Fisheries: Current Research
Improving Rebuilding Plans for Overfished West Coast Fish Stocks Through Inclusion of Climate Information
- Nate Mantua UW Climate Impacts Group
The Magnuson-Stevens Fisheries Conservation and Management Act mandates that overfished fish stocks be rebuilt in as short a time as possible. A key component of a rebuilding plan is a technical rebuilding analysis. Rebuilding analyses determine the trade-off between the time for the stock to recover to the population size at which Maximum Sustainable Yield is achieved, BMSY, and the fishing mortality during the period of rebuilding. However, the results of rebuilding analyses may be impacted by climatic regime shifts that impact both stock productivity and BMSY The aims of this project are to: a) assess whether climate indices can be linked to measures of productivity for fish stocks off the U.S. west coast, and b) modify existing tools for conducting rebuilding analyses to include climate impacts (and their associated uncertainties).
As part of this study, we have submitted a manuscript that compares two commonly used methods for identifying spring transition in the California Current that use data on wind-driven upwelling and coastal sea levels to two newly developed methods that use data on sea levels as well as satellite-derived sea-surface temperatures (SST). We assessed whether methods typically used in northern regions of the California Current could be applied to other regions. To demonstrate the biological implications of those methods, we evaluated relationships between timing of spring transition and recruitment of two groundfish species, Pacific ocean perch (Sebastes alutus) and sablefish (Anoplopoma fimbria).
Our results suggest that while dramatic changes in wind-derived upwelling and coastal sea levels consistently indicate spring transition in the northern California Current, this is not the case for central and southern regions. In those regions, spring transition may be better represented by the rate of change in sea levels and/or changes in spatial patterns of SSTs. Only metrics based on wind-driven upwelling and sea levels were related to groundfish recruitment; when transitions in upwelling and sea levels were delayed, recruitment tended to be poor. Although spatial-temporal patterns in SSTs were not related to recruitment, they may correlate with other biological variables not investigated here. We advise caution when identifying dates of spring transition and applying them to analyses of ecological phenomena; a combination of several methods may be required to reveal the multidimensional physical and biological changes that occur during that transition.
NOAA's Northwest Fisheries Science Center, NASA's Jet Propulsion Lab
NASA Jet Propulsion Lab
For more publications on CIG's research on climate and aquatic ecosystems, please see CIG Publications.
Hare, S. R. and N. J. Mantua. 2000. Empirical evidence for North Pacific regime shifts in 1977 and 1989. Progress in Oceanography 47:103-145.