An Aerial Survey Method for Estimation of Boater Use in Biscayne National Park During 2003-2004

Over the past several decades, the combination of rapidly growing human populations, overfishing, and habitat alterations have placed significant stress on marine resources in the Florida Keys ecosystem, including Biscayne National Park. In response to concerns about resource sustainability, the Park is currently formulating management plans to balance Park visitor use and impacts on fishery and habitat resources. A key information need in this planning effort is the extent of boater use in Park waters. This study was undertaken to establish a costeffective method for estimating boater use of Biscayne National Park. The study plan was to conduct an aerial census of vessels in Park waters, conduct a concurrent census of boat trailers at major public boat ramps in and around the Park, and use the vessel and trailer data to develop a statistical model for predicting total boater use. The complexity of the study environment required development of a mobile GIS recording system to collect real-time in-flight data on vessel usage including position (latitude and longitude), time of sighting, vessel number and characterization, and disposition. Direct counts of vessels within Park waters were obtained using a small fixed-wing Cessna 182 aircraft. A census of boat trailers was carried out on the same days and time frames (1200-1500h) as the flight surveys at five public marinas. A total of 52 vessel-trailer surveys were conducted from March 2003 to February 2004. Sampling effort was allocated by season (spring, summer, fall, and winter) and day of the week category (midweek and weekend/holiday) to conduct the vessel-trailer surveys on days that reflected the full gradient of boater use of Park waters, from lowest-use to highest-use days. Our results showed that the number of trailers at public marinas was a generally good predictor of the number of boats in Park waters.

The to develop an aerial survey GIS database which will also be instrumental for ongoing and future studies evaluating biological and socioeconomic aspects of Park visitor use, including estimation of spatial fishing effort.

Rrecommendations for precise estimation of boater use in

Biscayne National Park are:

• Implement an automated system for obtaining daily trailer counts at the following 5 marinas:

Homestead/Bayfront Park, Black Point, Matheson Hammock, Dinner Key, and Crandon Park.

• Calibrate and verify automated trailer counts with occasional direct trailer counts by creel census personnel.

• Use the combined season boat-trailer regression model,

Boats= 44.279 + 0.9577*Trailers (r2=0.943) for estimation.

• Conduct aerial surveys to obtain vessel counts on special high-use days (e.g., Columbus Day Regatta weekend, lobster mini-season, etc.), since model predictions may be unreliable.