“Boaters are held responsible if they damage seagrasses.” |
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| Faye Grubbs, Texas Parks and Wildlife Department | |
When it became evident that seagrass beds in Texas were being severely damaged by the propellers of recreational boats, coastal resource managers took regulatory action. A monitoring program incorporating a geographic information system (GIS) and aerial photography has been able to show that the new protective measures are being effective.
“This new regulation has definitely made a difference,” says Faye Grubbs, a natural resource specialist with Coastal Fisheries in the Texas Parks and Wildlife Department. “We not only have the aerial imagery showing this, but those results have been supported by visual observations and the physical counting of prop scars.”
Grubbs notes that extensive outreach has also contributed significantly to the success of the new rule, which makes it illegal to uproot any of the five species of seagrasses found throughout the Redfish Bay State Scientific Area.
“People are definitely more aware of seagrass, its importance ecologically, and how they can change their behavior to avoid damaging it,” she says.
More Than a Nursery
A seagrass meadow supplies everything that many marine organisms need, including being “the nursery, the roof over their heads, and the grocery store all rolled into one,” Grubbs says.
Over time, there has been a general decline in seagrass coverage in Redfish Bay caused by propeller scars—or “prop scars”—where boat propellers cut trenches into the bay floor. Prop scars can take from one to seven years to heal. If currents erode them, they may never recover.
Voluntary Action
Because of the proliferation of prop scarring, in 2000 the Texas Parks and Wildlife Department designated Redfish Bay as a scientific area. Three voluntary no-prop zones were marked with posts and signs visible to boaters.
In the summer of 2005, analysis found continued prop scarring in those areas. “The voluntary measures were basically ineffective,” Grubbs says.
Getting Serious
A “first of its kind” regulation affecting all Redfish Bay boaters went into effect on May 1, 2006, making it illegal to uproot seagrass with an outboard propeller. “It doesn’t include any closed areas, but boaters are held responsible if they damage seagrasses,” Grubbs says.
Local game wardens act as both educators and enforcers. Boaters who are caught uprooting seagrasses can receive a fine of up to $500.
Since 2007, after a one-year grace period to help educate boaters about the regulations, 12 boaters have been convicted.
Making an Impression
Grubbs says extensive outreach by the state and area nonprofits has helped ensure that boaters are aware of the regulations and how to respond when boating near seagrass. Outreach has included public service announcements, brochures, group presentations, and talking with boaters one-on-one.
Department staff members have also been featured in many media articles and programs. “We estimate 10.2 million impressions made through those venues,” she says.
Aerial View
Since the regulation went into effect, monitoring has been conducted to assess how well it’s working. A variety of monitoring techniques are being used, including capturing aerial photography in 2007, 2008, and 2009 on 8,000 acres of the bay, and analyzing prop scarring using a GIS.
Ashley Summers, Coastal Fisheries GIS analyst for Texas Parks and Wildlife, notes that in 2007, “NOAA did a prop scar assessment in Redfish Bay to determine how different aerial cameras work. They quantified the scars using an automated feature extraction tool, where you train a computer program to look at imagery and pull out the features that you are most interested in.”
Summers says they started with the idea of using the feature extraction tool to do annual assessments but discovered some systematic problems. Instead, they shifted their efforts to selecting a sample and visually inspecting the aerial photographs for scarring.
Scars on the bay are also assessed by swimming transects and ground truthing.
“It is a huge time commitment for a GIS analyst,” acknowledges Summers, “but getting the aerial imagery is worth it. You can assess a lot more of the bay in comparison to the time it takes field crews to go out and manually inspect.”
Changing Behavior
While it’s still early, a concurrent study in the same area showed a 45 percent decrease in scarring since 2005. “We feel very confident that the regulation is in fact working,” Grubbs says.
She adds, “Ultimately, this regulation is really changing the way people are boating through this area. It’s really informed the public about why it’s important to protect this resource.”
For more information on Texas efforts to protect seagrasses, go to www.tpwd.state.tx.us/landwater/water/habitats/seagrass/. You may also contact Faye Grubbs at (361) 729-2328 or Faye.Grubbs@tpwd.state.tx.us, or Ashley Summers at (512) 389-8199 or Ashley.Summers@tpwd.state.tx.us.
