Efficacy of voluntary mitigation in reducing harbor seal disturbance

Abstract

Marine and coastal tourism has rapidly expanded worldwide in the past 2 decades, often occurring in once secluded habitats. In Alaska, tourism near tidewater glaciers has attracted millions of visitors and increased the presence of ships, tour vessels, and coastal development. Although sustainable tourism, resulting from balanced effects on wildlife and client satisfaction, is a goal of most tourism operators, it is not always achieved. Voluntary compliance with viewing guidelines and codes of conduct have been encouraged, but few assessments have the longitudinal scope to evaluate long‐term changes in impacts on wildlife and the ability of vessel operators and kayak guides to sustain lower impact operating practices over time. This study assessed vessel and kayak visitation and resulting impacts on harbor seals in the Kenai Fjords National Park, southcentral Alaska. We obtained observations from 2002 to 2011, using remotely controlled video cameras located near Aialik and Pedersen Glaciers in the Kenai Fjords National Park. Overall, disturbance was associated with 5.1% of vessel sightings, 28% of vessel interactions (vessel observed within approx. 300 m of seals), 11.5% of kayak sightings, and 61% of kayak interactions. Results demonstrated that voluntary changes in operations significantly reduced vessel and kayak disturbance of seals by 60–80%. Even with prior establishment of operating guidelines, tour vessel captains were able to further reduce their effect on wildlife with more careful operations. Rapid growth of guided kayak excursions that occurred during this study caused greater disturbance to seals than motorized vessels but guide trainings helped reduce disturbances. Diminished impacts of motor vessels and kayakers persisted across years although effects of kayaks were less consistent than motor vessels, which reflected greater variability in inter‐annual spatial use patterns by kayakers. Long‐term monitoring, including assessments of wildlife responses to vessel and kayak operations, combined with 2‐way communication with vessel operators and guides, enhanced the effectiveness of mitigation and facilitated adaptive adjustments to mitigation protocols over time. © 2013 The Wildlife Society.

Haul-out patterns and effects of vessel disturbance on harbor seals (Phoca vitulina) on glacial ice in Tracy Arm, Alaska

“…Observations were made from 27 May through 30 June 2001. entering the water increases with decreasing seal-vessel distance (Figs. 5 and 7)-a finding that agrees with those of other studies (Calambokidis et al 1 ;Jezierski, 2009;Jansen et al, 2010;Hoover-Miller et al, 2013, Young et al, 2014. However, seals in Tracy Arm during our study appeared to be less responsive to vessels at a given distance than seals in Disenchantment Bay, where only cruise ships were monitored (Jansen et al, 2010), and in Muir Inlet in GBNP where all vessel types were monitored (Calambokidis et al 1 ), and they were far less sensitive than seals in Johns Hopkins Inlet in GBNP (Young et al, 2014), even when accounting for vessel type.…”

“…Some other studies had also noted that kayaks disturb seals at greater distances than those of motorized vessel types (e.g., power boats) (Jezierski, 2009;Hoover-Miller et al, 2013), but Calambokidis et al 1 found that harbor seals were equally sensitive to kayaks and tour boats (and less sensitive to pleasure boats [i.e., private vessels in our study]) and Young et al (2014) found seals were less sensitive to kayaks than any type of power vessel. It is possible that harbor seals can habituate to the noise of power boats and can determine a boat's approximate location by the sound of its engine.…”

“…These visits introduce the potential for the disturbance of seals and other wildlife in these fjords. With dramatic increases in tourism in Alaska and worldwide over the past 2 decades, and the coincident high use of glacial fjords during summer by both harbor seals and tourists, the possibility for unintended harassment of seals increases-harassment that is in violation of the Marine Mammal Pro-tection Act (Calambokidis et al 1 ; Allen 2 ; Suryan and Harvey, 1999;Henry and Hammill, 2001;Johnson and Acevedo-Gutiérrez, 2007;Jezierski, 2009;Young, 2009;Jansen et al, 2010;Hoover-Miller et al, 2013). From May through September, approximately 850 cruise ship trips carrying a total of nearly 1 million passengers visit southeastern Alaska each year (Nuka Research and Planning Group 3 ).…”

“…Wald chi-square statistics (P>~0.05) were used to eliminate unimportant variables one at a time (Hosmer and Lemeshow, 2000). After this model fitting (i.e., after we determined useful environmental predictors), mother-pup pairs and vessel predictors were included and evaluated in the same way.…”

“…The effect of age and distance class*age were investigated by using a data set that separated observations of pups and nonpups; a data set that included both pups and nonpups was used to investigate all other predictors. For 2 distance*vessel categories (skiff: >300 m; kayak: >300 m), there were no observations of seals entering the water-a situation that prevented successful model fitting and estimation of parameters (Hosmer and Lemeshow, 2000). To overcome this problem and facilitate model fitting, we added 0.1 (i.e., added one-tenth of a water entry) to one observation in each category.…”