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What's in a number? Giving a score to Puget Sound recovery

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The Ocean Health Index (OHI) project lead Ben Halpern of UC Santa Barbara was at the Center for Urban Waters in Tacoma yesterday to discuss the applicability of the OHI to the Puget Sound scale. Halpern's group will be engaging in discussions along these lines with the the Puget Sound Partnership through the spring and summer. 

The Ocean Health Index (OHI) project lead Ben Halpern of UC Santa Barbara was at the Center for Urban Waters in Tacoma yesterday to discuss the applicability of the OHI to the Puget Sound scale. Halpern's group will be engaging in discussions along these lines with the the Puget Sound Partnership through the spring and summer. 

The OHI is a relatively new framework that uses a complex set of metrics to score the health of the world's oceans from 0 to 100. The score is based on ten factors ranging from food provision (fisheries and mariculture) to carbon storage, tourism, clean waters, biodiversity and even "sense of place." View all ten factors here. It calls these "human goals, which represent the key ecological, social and economic benefits that a healthy ocean provides."

Yesterday's panel discussion included Halpern, one of the OHI's lead architects, and Ray Hilborn, a leading OHI critic based at the University of Washington School of Aquatic and Fishery Sciences. Hilborn wrote a critique of the OHI's food provision metric in last week's issue of the journal Nature, and he pulled no punches as a panelist on Tuesday. He maintained that the index doesn't describe "health" at all— calling such a designation too vague— and that the fisheries metric in particular is inaccurate. (Halpern has written a response to the critique, which will appear in an upcoming issue.)

Taking the middle ground was panelist Phil Levin of NOAA Fisheries, who joked that he agreed with both Halpern and Hilborn in equal measure, arguing that while boiling something as complex as the health of an entire ocean down to a single number may be reductive, the process of getting to that number is kind of interesting.  

OHI's proponents may not see the resulting score as being as important as the evaluation process. By weighting and assigning value to certain ecosystem components, the OHI wants you to ask what matters— what are your priorities, and what are the key drivers of ecosystem change?  Halpern argues that people such as managers and policymakers are making value judgements like these all the time. "People are doing this in their heads anyway," he says. Why not then create a framework that makes the process transparent?

If some of the work around the OHI sounds familiar to scientists working in the Puget Sound ecosystem, it is because groups like the Puget Sound Partnership, and to an extent the Puget Sound Institute, have been involved for a while in a process of identifying indicators for Puget Sound health. The Partnership's "vital signs" are aimed at a watershed scale, but some of the underlying goals are the same as the OHI. The Partnership hopes to use the vital signs to provide a snapshot for identifying and conveying progress in the effort to protect and restore Puget Sound.

Much of the panel discussion centered around the OHI itself, but a question for the future will be how the OHI scales to the much smaller Puget Sound ecosystem. The OHI is also concerned primarily with marine waters, whereas management efforts by the Puget Sound Partnership have focused on the entire watershed. The unique estuarine nature of Puget Sound raises a further question. Would the OHI indices fit such a system? Halpern and his group say they hope to look closer at many of these questions over the course of the next year.