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A Statistical Method for Analyzing Data Collected by a Creel/Angler Survey (Part 2)
Abstract
This article describes a unique analytical method employed to characterize angler activities on the lower 6-mile stretch of the Passaic River in New Jersey. The method used data collected by a creel/angler survey that was designed to capture the information necessary to calculate the exposure factors needed to characterize the fish consumption pathway for recreational anglers in a human health risk assessment for the river. The survey used two methods to address the challenges of conducting a creel/angler survey in an urban and industrial setting with limited river access. While unique, the analytical method described in this article is based upon accepted methods of interpreting survey data and basic laws of probability. This article was written as a companion to two other articles, also in this issue and cited here, of which one describes in detail the survey methodology designed for the lower Passaic River creel/angler survey to meet various challenges unique to conducting such a survey in urban and industrialized rivers, and the other presents, validates, and interprets the results of the lower Passaic River work relating to human exposure factors using the methodology described in this article.
... This study used the weighting approach developed for the Passaic River Creel and Angling Survey, (3,6,7) which has been peer reviewed and accepted as an appropriate technique. (8) This approach was designed for an infrequently visited system and improves upon earlier attempts to correct for avidity bias, such as that developed by Price et al. (9) The sampling weight (w i ) for an angler interview is the inverse of the probability (p) that the respondent is interviewed at least once during the study period. ...
... where pn ij is the probability of angler i not being interviewed in stratum j. Ray et al. (6) show that the probability of not being interviewed within a stratum is represented by the hypergeometric distribution parameterized using the number of interviews for that angler (in this case, 0), the angler's trips within that stratum (t ij ), the number of times that stratum was sampled (n j ), and the total number of opportunities to sample within that stratum (N j ): ...
A one-year angler intercept survey was conducted on Choccolocco Creek, a rural, limited access tributary to the Coosa River in northeastern Alabama. The purpose of the survey was to collect data and information about the behaviors and fish consumption habits of the recreational anglers who fish there. Nine survey locations were included in the stratified sampling plan, and sampling occurred throughout daylight hours, on weekdays and weekends/holidays, during all four seasons of the year. Surveys were completed on a total of 101 survey days between June 28, 2008 and June 27, 2009.(6) Seventy-two anglers were observed fishing during the survey period, and 52 (72%) of those individuals agreed to participate in the survey. Based on the information collected by the survey clerks, the angler population fishes the Creek between 1 and 54 times per year, with an average frequency of seven trips per year. The average number of months fished was three months per year, with a range of one to nine months. Only 15% of the anglers who participated in the survey (eight individuals) had succeeded in catching fish by the end of their trips, and only four of those individuals (8%) had retained any of the fish they had caught for consumption. Reasons provided for not retaining fish were that they either only fished for sport, did not catch enough fish to eat, or the fish they caught were too small to keep. Because so few anglers used and harvested fish from the resource, fish consumption rates could not be determined with a high degree of confidence. However, from these limited data it was estimated that the three anglers for whom consumption rates could be estimated had annualized average daily fish consumption rates of 0.14, 0.44, and 7.9 grams per day (g/day). The majority of anglers traveled less than 10 miles to fish the Creek. It was estimated that a total population of 173 anglers use the Creek each year. The results of this survey indicated that Choccolocco Creek is a local fishery that is not heavily used by area residents.
... Confidence limits were also derived as described in the work of Haas et al. (27).29, 41, 42), and USEPA considered this to be a complete pathway in their draft risk assessment of the Lower Passaic River (7). Again, a triangular distribution was assumed for incidental ingestion (mg/day) for adults and adolescents (minimum 25, mode 50, maximum 95). ...
High levels of pathogenic microorganisms have been documented previously in waters of the Lower Passaic River in northern New Jersey. The purpose of this study was to characterize the microbial contamination of river sediments near combined sewer overflows (CSOs), a known source of pathogens. Concentrations of fecal coliform, total coliform, fecal Streptococcus, fecal Enterococcus, Pseudomonas aeruginosa, Staphylococcus aureus, Giardia lamblia, and Cryptosporidium parvum organisms were measured in 16 samples from three mudflat locations along the Lower Passaic River, as well as from an upstream location. Selected samples were also analyzed for antibiotic resistance. All of the samples contained high concentrations of total coliform, fecal coliform, fecal Streptococcus, and fecal Enterococcus organisms. Analysis of isolates of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli from several samples indicated that each strain was resistant to at least one antibiotic typically used in clinical settings. Eight of 16 samples contained Giardia, and one sample contained Cryptosporidium. With these sampling data, a quantitative microbial risk assessment was conducted to evaluate the probability of infection or illness resulting from incidental ingestion of contaminated sediments over a 1-year period. Three potential exposure scenarios were considered: visitor, recreator, and homeless person. Single-event risk was first evaluated for the three individual exposure scenarios; overall risk was then determined over a 1-year period using Monte Carlo techniques to characterize uncertainty. For fecal Streptococcus and Enterococcus, annualized risk estimates for gastrointestinal illness ranged from approximately 0.42 to 0.53 for recreators, 0.07 to 0.10 for visitors, and 0.62 to 0.72 for homeless individuals across the three sampling locations. Annualized risk of Giardia infection ranged from 0.14 to 0.64 for recreators, 0.01 to 0.1 for visitors, and 0.30 to 0.87 for homeless individuals, across all locations where detected. Cryptosporidium was detected at one location, and the corresponding annualized risk of infection was 0.32, 0.05, and 0.51 for recreators, visitors, and homeless individuals, respectively. This risk assessment suggests that pathogen-contaminated sediments near areas of CSO discharge in the Lower Passaic River could pose a health risk to individuals coming into contact with sediments in the mudflat areas.
A one-year angler intercept survey was conducted on the lower 17 miles of the Passaic River, an urban industrialized river that flows through Newark, New Jersey. The purpose of the survey was to collect data about anglers’ behaviors and fish consumption habits in order to calculate exposure factors for a human health risk assessment of the Study Area. This paper focuses on estimating site-specific fish consumption rates for LPRSA anglers that consume their catch. The study design included on-site interviews and counts (angler enumeration). Forty survey locations were included in the stratified random sampling plan; interviews were conducted on 136 days and counts on 164 days. After matching intercepts with the same angler, a total of 294 anglers were interviewed, of which 25 reported consuming their catch. LPRSA fishing trips ranged from 2 to nearly 50 annual trips for anglers who reported consuming their catch. Species caught and reported to be consumed included carp, catfish, white perch, smallmouth bass, and eel. The estimated mean and 90th percentile consumption rates for the population of consuming anglers are 5.0 and 8.8 g/day, respectively. Based on sensitivity analyses, the 90th percentile fish consumption rates range from approximately 4 to 18 g/day.
Although many recreational anglers reside in urban areas, important policy questions, such as how to optimally improve urban shorelines and increase urban angler participation rates, are unresolved. This article presents an econometric model that quantifies the relationships between site quality, angler characteristics, and urban angling behavior in five northeastern New Jersey counties. The model employed (repeated nested logit) is prominent in the environmental economics literature but has not to our knowledge been applied to urban fishery management. The results indicate that the repeated nested logit can effectively characterize urban anglers’ site choices, participation rates, and resource values. The article presents two models whose differences highlight considerations in modeling urban angling behavior. The first includes variables typically found in recreational-fishing, site-choice models. The second (and preferred) model includes variables that more appropriately characterize urban angling. This model predicts approximately 2,341,000 total annual trips. Adding a fishing site in a centrally located but industrial area (Newark) generates direct economic benefits to recreational anglers that are estimated at US312,419 per year. This new site draws an expected 14,814 trips annually. Of these trips, 247 arise from increased angling rates and 14,567 are diverted from other sites. These results illustrate the usefulness of this modeling approach for assessing management objectives. For example, a manager hoping to increase angling participation might prefer the Newark project if it could be completed at half the price; a manager intending to maximize social benefits or reduce pressure at other sites would pay a substantial premium for the Garfield project.Received November 3, 2009; accepted December 30, 2010
Urban et al. (2009) presented a human health risk assessment for the Lower Passaic River that very narrowly defines fish consumption, ignores crab consumption, and is not consistent with current NJ or EPA risk assessment procedures and guidance. The restrictively defined consumption then leads to inappropriate conclusions on the risk of eating fish from this highly contaminated estuarine river. The paper underestimates angler exposure to contaminated fish, does not evaluate exposure to contaminated crab, and underestimates the cancer risks and non-cancer health hazards associated with these exposure pathways. The New Jersey Department of Environmental Protection along with the NJ Department of Health and Senior Services issues fish and crab consumption advisories for all state waters; these advisories should be followed for the Passaic River and surrounding waters: http://www.state.nj.us/dep/dsr/FishSmartEatSmartNJ.org.
The Lower Passaic River (LPR) in New Jersey has been impacted by variety of human activities over the course of the last two centuries. In this risk assessment, we assessed potential human health risks associated with consumption of fish from the LPR, the human exposure pathway of greatest concern when addressing contaminated sediments. Our risk assessment incorporates fish consumption information gathered during a year-long, intercept-style creel angler survey and representative fish tissue concentrations for 156 chemicals of potential concern (COPCs) obtained from USEPA's public database (OurPassaic website: http://www.ourpassaic.org/projectsites/premis_public/index.cfm?fuseaction=contaminants). Due to the large number of COPCs investigated, this risk assessment was divided into two phases: (1) identification of COPCs that contribute to the majority of overall excess cancer risk and hazard estimates using deterministic and probabilistic methods, and (2) probabilistic characterization of risk using distributions of chemical concentration and cooking loss for those compounds identified in Phase 1. Phase 1 relied on point estimates of COPC concentrations and demonstrated that PCDD/Fs and PCBs (dioxin-like and non-dioxin-like) are the greatest contributors to cancer risk, while non-dioxin-like PCBs are the primary contributors to non-cancer hazard estimates. Total excess cancer risks for adult and child and receptors estimated in Phase 1 were within USEPA's acceptable excess cancer risk range, with the exception of RME child (3.0 x 10(-4) and 1.3 x 10(-4) for deterministic and probabilistic approaches, respectively). Phase 2 focused on PCDD, PCDF, and PCBs and used distributions of chemical concentrations in fish. The results showed that all excess cancer risk estimates were within the acceptable risk range, although non-cancer hazard estimates for PCBs slightly exceeded a Hazard Index of 1. This HHRA of LPR fish ingestion represents the most comprehensive evaluation conducted to date, and demonstrates that measured concentrations of COPCs are not likely to pose a health risk to people who currently consume fish from the LPR.
The potential human health risks associated with consuming fish containing hazardous substances are related to the frequency, duration, and magnitude of exposure. Because these risk factors are often site specific, they require site-specific data. In anticipation of performing a risk assessment of the lower 6 miles of the Passaic River in New Jersey (Study Area), a year-long creel/angler survey collected such site-specific data. The lower Passaic River is urbanized and industrialized, and its site conditions present unique survey design and sampling challenges. For example, the combined population of the municipalities surrounding the Study Area is nearly 330,000, but because the Study Area is tidal, state law does not require fishing licenses for anglers to fish or crab in the Study Area. The sampling challenges posed by the lack of licensing are exacerbated by the industrialization and lack of public access in the lower half of the Study Area. This article presents a survey methodology designed to overcome these challenges to provide data for accurately estimating the Study Area's angling population and the fish and crabs they catch, keep, and eat. In addition to addressing the challenges posed by an urban and industrial setting, the survey methodology also addresses the issues of coverage, avidity, and deterrence, issues necessary for collecting a representative sample of the Study Area's anglers. This article is a companion to two other articles. The first companion article describes the analytical methodology designed to process the data collected during the survey. The second presents, validates, and interprets the survey results relating to human exposure factors for the lower Passaic River.
During precipitation events, untreated human sewage is often intentionally discharged to surface water bodies via combined sewer overflow (CSO) systems in order to avoid overloading wastewater treatment plants. The purpose of this analysis was to evaluate the risk of pathogen-related disease associated with CSO discharges into the Lower Passaic River. Concentrations of fecal coliform, total coliform, fecal Streptococcus, and fecal Enterococcus bacteria were measured at six river locations on six different days in 2003 (n = 36). In addition, water samples (n = 2) were collected directly from and in the immediate vicinity of a discharging CSO in Newark, NJ. These samples were analyzed for fecal coliforms, total coliforms, fecal Streptococcus, fecal Enterococcus, Giardia lamblia, Cryptosporidium parvum, and several viruses. Risk estimates for gastrointestinal illness and Giardia infection resulting from indirect and direct ingestion of contaminated water were calculated for three potential exposure scenarios: visitor, recreator, and homeless person. Single-event risk was first evaluated for the three individual exposure scenarios; overall risk was then determined over a 1-year period. Monte Carlo techniques were used to characterize uncertainty. Nearly all of the pathogen concentrations measured in the Passaic River exceeded health-based water quality criteria and in some cases were similar to levels reported for raw sewage. The probability of contracting gastrointestinal illness due to fecal Streptococcus and Enterococcus from incidental ingestion of water over the course of a year ranged from 0.14 to nearly 0.70 for the visitor and recreator scenarios, respectively. For the homeless person exposure scenario, the risk for gastrointestinal illness reached 0.88 for fecal Streptococcus and Enterococcus, while the probability of Giardia infection was 1.0. This risk analysis suggests that, due to the levels of pathogens present in the Lower Passaic River, contact with the water poses, and will continue to pose, significant human health risks until CSO discharges are adequately controlled or abated.
A Creel/Angler Survey (CAS) was conducted to provide site-specific information on recreational fishing in the lower six miles of the Passaic River (Study Area). Information collected during the CAS will be used to develop site-specific exposure factors, including fish consumption rates, for use in the human health risk assessment required by an Administrative Order on Consent as part of the Remedial Investigation/Feasibility Study for the Study Area. An expert panel was convened to provide an independent opinion regarding the need for, design of, and implementation of the CAS. The expert panel was charged with evaluating whether the conduct of a CAS is necessary to support an accurate risk assessment for the Study Area and whether the proposed CAS is sufficient to characterize local fish consumption behavior for risk assessment purposes. The expert panel agreed that a CAS is necessary and concluded that the proposed CAS, with specific modifications to the study design and data analysis, would provide the information necessary to estimate site-specific fish consumption rates. Revision of the CAS to accommodate the expert panel recommendations enhanced the quality of the data collected and ensured that the data will support the assessment of human health risks from consumption of fish from the Study Area.
We develop a "perceived hazard" model that estimates consumers' endogenous risk perceptions about products. These perceptions are then linked to a model of product choice. Our approach thus departs from the expected utility model that depends upon external risk assessments. In an application to recreational fishing, we find that anglers' perceived hazards associated with fish consumption advisories do affect product (recreational site) choice. Anglers' perceptions also affect welfare measures because the benefits of contaminant removal flow from these perceptions. The perceived hazard/product choice model is applicable to a wide variety of risky choices consumers face. Copyright 2003 by Kluwer Academic Publishers
EPA guidance recommends that 30 grams per day be used to represent the consumption rate of fish caught from large bodies of water by a typical angler. This estimate is based on the combined results of the Pierce et al. and Puffer et al. surveys of marine and estuarine anglers. An examination of these surveys demonstrates that the method used in both studies - creel survey - oversamples frequent anglers and produces a distribution of consumption rates that overestimates intake rates of the total angler population using the surveyed waterbodies. Weighting the individual survey responses by the inverse of the angler self-reported fishing frequency corrects this bias and produces a more accurate characterization of the total population of anglers using the surveyed waterbodies. This approach is an extension of the methodology used by both Puffer et al. and Pierce et al. to estimate the size of the total angler populations. The results of the reanalysis of the Pierce et al. survey indicate that the median consumption rate for the total angler population is 1.0 g/d. The results of the Puffer et al. reanalysis indicate a median consumption rate for total angler population of 2.9 g/d. The recalculated distributions of consumption rates were found to be consistent with the results of other angler surveys that use survey methods that do not oversample frequent anglers. The angler intake rate of 30 g/d corresponds to roughly the 90th and 95th percentiles of the total angler populations in the Pierce et al. and Puffer et al. surveys respectively. The results of this paper indicate that the current estimate of 30 g/d significantly overestimates consumption for typical marine and estuarine anglers.
The results of an analysis of site-specific creel and angler information collected for the lower 6 miles of the Passaic River in Newark, NJ (Study Area), demonstrate that performing a site-specific creel/angler survey was essential to capture the unique characteristics of the anglers using the Study Area. The results presented were developed using a unique methodology for calculating site-specific, human exposure estimates from data collected in this unique urban/industrial setting. The site-specific human exposure factors calculated and presented include (1) size of angler population and fish-consuming population, (2) annual fish consumption rate, (3) duration of anglers' fishing careers, (4) cooking methods for the fish consumed, and (5) demographic information. Sensitivity and validation analyses were performed, and results were found to be useful for performing a site-specific, human health risk assessment. It was also concluded that site-specific exposure factor values are preferable to less representative "default values." The results of the analysis showed that the size of the angling population at the Study Area is estimated to range from 154 to 385 anglers, based on different methods of matching intercepts with anglers. Thirty-four anglers were estimated to have consumed fish; 37 people consumed fish from the river. The fish consumption rate for anglers using this area was best represented as 0.42 g/day for the central tendency and 1.8 g/day for the 95th percentile estimates. Anglers fishing at the river have relatively short fishing careers with a median of 0.9 yr, an average of 1.5 yr, and a 95th percentile of 4.8 yr. Consuming anglers tend to fry the fish they caught. The demographics of anglers who consume fish do not appear to differ substantially from those who do not, with no indication of a subsistence angling population.
The potential human health risks associated with consuming fish containing hazardous substances are related to the frequency, duration, and magnitude of exposure. Because these risk factors are often site specific, they require site-specific data. In anticipation of performing a risk assessment of the lower 6 miles of the Passaic River in New Jersey (Study Area), a year-long creel/angler survey collected such site-specific data. The lower Passaic River is urbanized and industrialized, and its site conditions present unique survey design and sampling challenges. For example, the combined population of the municipalities surrounding the Study Area is nearly 330,000, but because the Study Area is tidal, state law does not require fishing licenses for anglers to fish or crab in the Study Area. The sampling challenges posed by the lack of licensing are exacerbated by the industrialization and lack of public access in the lower half of the Study Area. This article presents a survey methodology designed to overcome these challenges to provide data for accurately estimating the Study Area's angling population and the fish and crabs they catch, keep, and eat. In addition to addressing the challenges posed by an urban and industrial setting, the survey methodology also addresses the issues of coverage, avidity, and deterrence, issues necessary for collecting a representative sample of the Study Area's anglers. This article is a companion to two other articles. The first companion article describes the analytical methodology designed to process the data collected during the survey. The second presents, validates, and interprets the survey results relating to human exposure factors for the lower Passaic River.
National Marine Fisheries Service Marine recreational fisheries statistics— National Marine Fisheries Service—Marine Recreational Fisheries Statistics Survey Angler survey methods and their applications in fisheries management
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New York: John Wiley & Sons. National Marine Fisheries Service. 2000. Marine recreational fisheries statistics— National Marine Fisheries Service—Marine Recreational Fisheries Statistics Survey, ed. J. F. Witzig. Retrieved February 5, 2000. Available at http:// www.st.nmfs.gov/recreational/survey/overview.html. Pollock, K. H., Jones, C. M., and Brown, T. L. 1994. Angler survey methods and their applications in fisheries management, pp. 136, 287. Special Publication 25. Bethesda, MD: American Fisheries Society.
Integration of risk assessment and natural resource damage assessment: Case study of Lavaca Bay
- K E Mathews
- K J Gribben
- W H Desvousges
Mathews, K. E., Gribben, K. J., and Desvousges, W. H. 2002. Integration of risk assessment and natural resource damage assessment: Case study of Lavaca Bay. In Human and ecological risk assessment theory and practice, ed. D. J. Paustenbach, pp. 1161–1192.