Effects of Vessels on Harbor Seals in Glacier Bay National Park

We evaluated the effectiveness of harbor seal ( Phoca vitulina )-related vessel regulations in Glacier Bay National Park. We observed 100% compliance with area closures intended to minimize disturbance to dependent pups, yet dependent pups were still present in the inlet after the area was opened to vessels. Compliance with the 463 meter (m) minimum approach distance regulation by vessels was low (22%), although 33% of vessel–seal encounters resulted in disturbance when vessels were still >463 m from seals. Ice cover was the best predictor of disturbance. Our results indicated that vessel regulations might be variably effective due to biological irrelevance, noncompliance, or environmental factors. MPA regulations should be evaluated to ensure achievement of conservation objectives.