The Role of Fishing Piers in Brown Pelican (Pelecanus occidentalis) Entanglement

Abstract

Throughout their range, Brown Pelicans (Pelecanus occidentalis) are one of the most common species to become entangled in fishing gear. We surveyed four piers every other week for one year (6/2019−5/2020) in the Tampa Bay region, FL, USA, to determine frequency of pelican entanglement associated with fishing piers, and explored factors that might influence the rate of entanglement. We conducted a generalized linear model (GLM) to determine the influence that pier, pier closure due to COVID-19, time of day and season, number of anglers, and presence of human behaviors that might attract pelicans to the pier had on the number of entangled pelicans. We conducted 144 surveys and counted 3766 pelicans of which 254 (7%) were entangled. The variables significantly associated (p < 0.05) with entanglement were the pier, time of day, and pier closure status, while the number and behavior of anglers were not significant. The two piers that most significantly influenced the number of entanglements both had extensive perches within 10 m of the fishing pier. The management action most likely to reduce the number of entangled pelicans appears to be deterring pelicans from perching near piers or decreasing fishing near perching structures.

Keywords: Brown Pelican; COVID-19 closure; Pelecanus occidentalis; entanglement; fishing pier.

Figure 1

The four fishing piers located in the Tampa Bay region, Florida, USA. The Gulf and Bay piers are at Ft. De Soto County Park and the North and South Skyway piers are adjacent to the Sunshine Skyway Bridge.

Figure 2

Estimated marginal mean (SE bars) number of injured and dead Brown Pelicans at the four piers for each survey after controlling other variables in the model. The South Skyway and Gulf piers had significantly more injured and dead pelicans than the Bay and North Skyway piers (p < 0.05, LSD post hoc test). Sample size = 144 surveys.

Figure 3

Estimated marginal mean (SE bars) number of injured and dead Brown Pelicans during three times of day after controlling for the other variables in the model. The 7–10:59 am and 11–2:59 pm time periods had significantly more injured and dead pelicans than the 3–7 pm time period (p < 0.05, LSD post hoc test). Sample size = 144 surveys.