Backhoe Moving Fish Killed by Golden Alga at Lake Granbury. Photo courtesy Texas Parks & Wildlife Dept. © 2004In January through July 15, 2001, there was a confirmed outbreak of golden alga (Prymnesium parvum) at Possum Kingdom Lake (PKL) in Texas. The event was followed by two additional confirmed golden alga events at the PKL. As various fish populations at the lake have been affected and catchability (or perceived catchability) has been reduced, we expected recreational fishing at the lake by non-residents and residents alike to decrease and the regional economy (Palo Pinto, Stephens, and Young counties) to be impacted negatively.

 

The purpose of the study was to estimate the extent of economic impact associated with the algal events using three different time-series secondary data sets. First, data for sales tax and county level gross sales were obtained for five tourism-related SIC code categories (grocery stores, eating and drinking places, retail stores not else classified, hotels and motels, and miscellaneous amusement and recreation services) for the three county study area for the period starting with the first quarter of 1986 to the second quarter of 2004. Second, data for the number of visitors to PKL State Park were provided by TPWD for the period of September 1996 to January 2005. Third, monthly gross sales for recreational fishing related items were obtained for the years 1998- 2004 from the local store concession operating at the PKL State Park.

To examine the impacts of the 2001 and 2003 golden alga events, intervention analysis was used. ARIMA (AutoRegressive Integrate Moving-Average) models were used to test the effects of exogenous interventions. Using an intervention time-series modeling methodology with economic impact assessment, three intervention components (the 9-11 terrorist attacks and two algal blooms) were inserted to estimate the economic impacts of each event.

Economic Impact Losses

  • From the first golden alga event in 2001, total economic impact was estimated as a loss of $2.8 million, equivalent to about 5% of total output in the three counties in the PKL study area.
  • For comparison purposes, the 9-11 terrorist attacks on the U.S. and the second golden alga bloom were followed by economic losses of $2.2 million and $1.1 million, respectively.

State Park Visitation

  • The algal blooms in 2001 explained a 57% reduction in the number of visitors to PKL State park or about 4,793 per month.
  • The 9-11 terrorist attacks had a negative impact of 1,489 visitors.
  • The algal bloom in 2003 resulted in a reduction of 1,615 visitors.

Concessionaire Sales

  • The 2001 and 2003 algal blooms explained sales declines of $9,658 and $22,318, respectively for the business.
  • Interestingly, the 9-11 terrorist attacks indicated a positive impact on sales of $52,234, likely the result of people staying closer to home.

 

Prymnesium parvum. Photo by John Laclaire, courtesy Texas Parks & Wildlife Dept. © 2004The intervention time-series method provided a reliable tool for analyzing the influence of external events on various time series of interest. TPWD damage assessment values can be added to what we have reported here to more fully understand event impacts. It was impossible for us to focus our research exclusively on recreational fishing in the study area due to a lack of information specifically on recreational fishing. Also, there is no SIC code devoted exclusively to the recreational fishing business. Instead, we focused on outdoor recreation-related tourism as reflected by the SIC codes used. The total economic impact of golden alga at PKL might have been higher had other data and understandings been available to us regarding angler use of the lake, their willingness-to-pay above trip costs (consumer’s surplus) and their expenditures for fishing by category. Our results are likely reflective of recreational fishing since other recreation activities were not directly impacted by golden alga events. However, there is some likelihood that potential visitors who participate in other activities have been impacted.

In light of what anglers “know” about fishing at PKL, many are likely substituting other lakes in the region as fishing destinations that can be accessed at similar cost and yield the same level of angling satisfaction available previously at PKL. This pattern is also likely to continue to do so until their perceptions of PKL fishing change. What can be done to better understand/ offset these effects?

 

  • First, fishing at PKL needs to get as much good press and media coverage as possible. The coverage should be truthful and devoted to all types of fishing at PKL.
  • Second, it is in the best interest of the local area to encourage the TPWD-Inland Fisheries to institute an annual creel intercept survey at PKL. Because the TPWD does not conduct creel intercepts at each and every lake in Texas, some type of cost sharing arrangement may be necessary.
  • Third, when recreational fishing makes a full recovery at PKL, an angler survey should be completed using the creel intercept as a sampling frame as has been done previously at a number of other lakes in Texas. In the meantime, a survey of anglers in the Dallas- Ft.Worth Metroplex would be useful for understanding the distribution of current and previous angling activity by anglers residing in this region, and what the competition is for PKL in terms of other lakes available at a similar cost

Other Texas lakes known for their recreational fishing and tourism activity have much to learn from the PKL case. It is not just enough to say that recreational fishing is important to the local economy. A creel intercept survey as well as other types of data should be collected on a regular basis to ascertain recreational fishing use of the lake by month as well as use trends over time. This will allow for understanding the extent of impacts of various possible exogenous events (golden alga, oil spills, contaminants, drought, increased gasoline prices, etc.) on recreational fishing activity and related expenditures. Such a data base is a principal requirement for being in the tourism business and needs to be up and operational at all major Texas fishing lakes prior to any other such events so effects can be fully understood and remediation justified.

The Texas Parks and Wildlife Department funded this research project with additional funding support from the Texas Agricultural Experiment Station.

 

Final Report

 

Dr. Robert B. Ditton (r-ditton@tamu.edu) is the Principal Investigator for this project and Chi-Ok Oh (chibb@tamu.edu) is the Research Assistant for phase one of this study. Dr. Ditton is affiliated with Department of Wildlife and Fisheries Sciences at Texas A&M University, College Station, TX.

Picture 1: Backhoe Moving Fish Killed by Golden Alga at Lake Granbury. Photo courtesy Texas Parks & Wildlife Dept.© 2004
Picture 2: Prymnesium parvum. Photo by John Laclaire, courtesy Texas Parks & Wildlife Dept. © 2004  Back to top