Increasing Yellow Tang Abundance in West Hawai‘i and Resolution 130’s Relationship with the Data

administrator . News 2102

While some anti-trade activists have alluded to “other data” contradicting the data put forth by the state aquatic biologist Dr. William Walsh, I learned in my interview last Thursday with County Council Member Brenda Ford, who authored 130, that she believes Walsh’s data is sufficient to warrant a statewide ban. 
I was fortunate to have the opportunity to spend the better part of a day with Walsh while I was in Hawai‘i researching the story for MASNA and Coral Magazine. An edited (for space) version of my interview with Walsh will published in the Nov/Dec issue of Coral (the full interview will be available online), but I’d like to share a few highlights from the interview here.
An Apparent Flip-Flop on Management of the Marine Aquarium Fishery in Hawai‘i
Despite the apparent flip-flop of the Hawai‘i County Council from supporting the fishery management tools proposed last September and opposing a ban late this September to voting in favor of a ban in early October 2011, Walsh told me “nothing fundamental has changed since last year.” If anything, we know more about the fishery today, and there is more data to support Walsh’s assertion the fishery is moving in the direction of one that is well managed and sustainable.
So how is it Council Member Brenda Ford, the author of Resolution 130, claims Walsh’s data shows “devastation” necessitating a statewide ban on aquarium collection? The answer, I think, is quite simple. As I reported previously, many opponents of the aquarium fishery refuse to call the marine aquarium fishery a fishery, and Ford is no exception. As such, for Ford and others like Robert Wintner (aka Snorkel Bob), the commonly accepted litmus test for fishery sustainability (or lack thereof) does not apply. While I believe Ford’s assertion of devastation is worth exploring (the reefs of Hawai’i certainly are being heavily impacted by a wide range of anthropogenic stressors), it does not appear to be an assertion about sustainability using traditional fisheries management language.
A Fishery is a Fishery
Using the standard definition of a fishery widely accepted by fisheries biologists and others who manage and create legislation to manage fisheries, a marine aquarium fishery is really no different from a food fishery in terms of how it is defined and how sustainability is determined. The Magnuson-Stevens Fishery Conservation and Management Act, the primary law governing marine fisheries management in the United States (primarily in federal waters), asserts a fishery is “one or more stocks of fish which can be treated as a unit for purposes of conservation and management and which are identified on the basis of geographical, scientific, technical, recreational, and economic characteristic.” Likewise, according to the Magnuson-Stevens Act, “the term fishing means the catching, taking, or harvesting of fish.” Hawaii Administrative Rule 13-74 likewise defines fishing as “catching, taking, or harvesting, or attempting to catch, take, or harvest, aquatic life. The use of a pole, line, hook, net, trap, spear, or other gear which is designed to catch, take, or harvest aquatic life, by any person who is in he water, or in a vessel on the water, or on or about the shore where aquatic life can be caught…”
If we can agree the marine aquarium fishery is indeed a fishery (and that marine aquarium collectors are indeed fishers), then we can get down to brass tacks and ask the real question: Is the marine aquarium trade in West Hawai‘i being fished sustainably? 
The Magnuson-Stevens Act, states “the terms ‘overfishing’ and ‘overfished’ mean a rate or level of fishing mortality that jeopardizes the capacity of a fishery to produce the maximum sustainable yield on a continuing basis.” Is that what is happening on the reefs of Hawai‘i? Here is some data that may help us to answer that question. Everything below in quotation marks is a direct quotation from Walsh based on the data collected by DAR staff biologists and others along the Big Island’s Kona Coast. 
“In 2010 over 430,000 animals were collected on West Hawai‘i reefs with yellow tang comprising 81 percent of the catch,” says Walsh. “From 1999, when we began WHAP [the West Hawai‘i Aquarium Project], to 2010 the number of collected yellow tang increased from 165,254 to 311,480—an increase of about 88 percent.”
“From 1999 to 2010 the yellow tang population of mostly immature fish in the 30’-60’ depth range in West Hawai‘i increased from an estimated 2,236,858 to 2,573,909, an increase of 337,050 or slightly more than 15 percent. [For reasons explained in the full interview in Coral Magazine, that 15 percent statistic likely underestimates the West Hawai‘i yellow tang population increase since 1999.].” 
“Over this same time frame the number of collected yellow tangs has increased 88 percent. So while yellow tang take has increased along the coast over the past decade, the total abundance of yellow tangs has also increased.”
That Surely Doesn’t Look Like Devastation
That surely doesn’t look like devastation—in fact, it might even look like categorical sustainability everyone could embrace…except for the fact the data, averaged over the last three years, shows 68-percent less abundance of yellow tang in open areas compared to FRAs. Walsh told me this number concerns him, and opponents of the trade use this abundance differential statistic frequently to argue management is not working.
According to the data, the yellow tang is one of only six species on the proposed white list to show a consistently lower abundance in open areas than closed areas. Unlike the other five species, which show more variability, from 1999 to 2008 the disparity between the abundance of yellow tang in open areas and FRAs generally widened. Following a good recruitment year (and possibly recession impacts) the disparity has started to narrow in 2009 and 2010. 
I asked Walsh what he thought of the oft-cited disparity statistic, which is frequently used by opponents of the marine aquarium fishery. While Walsh says this number does concern him, and he says he wants to reduce it, he also points out the following:
“It is important to note that a large part of the difference in yellow tang abundance between the FRAs and the open areas relates to the fact that yellow tang abundance has increased so much in the FRAs—it’s up 71 percent since 1999. The protected areas are working very well. During this same time period the open areas have decreased by 19 percent [and] this is where the fishing—at increasing levels—occurs.” 
“Even if there was no decline in open area yellow tang abundance,” Walsh continues, “the difference between those areas and the FRAs would be substantial just due to the increased numbers of fish in the protected FRAs. Overall, on West Hawai‘i reefs as a whole, yellow tang populations have increased by 15 percent in the 30’-60’ depths since 1999.”
Other Species of Concern
For the record, I want to be very clear there are other targeted species to consider besides the yellow tang, but the yellow tang is the vast majority of the catch and it is the species that gets a lot of the airtime, so it’s a good place to start. In a future post, I’ll share some of the data showing downward trends in a few of the species currently targeted by the marine aquarium fishery on the Kona Coast of the Big Island. I assume these are the species, in addition to the yellow tang, about which Council Member Ford was speaking. I’ll also let you know what Walsh shared with me about the proposed management for those species. 
Spoiler alert: While there are indeed some downward trends in Walsh’s data, there is nothing I have seen leading me to conclude the fishery cannot be managed in a sustainable manner if we use science-based management and the widely accepted language of fisheries management.