Response by vessel operators to protection measures for right whales Eubalaena glacialis in the southeast US calving ground

Abstract

Vessel strikes are the leading cause of mortality for the endangered North Atlantic right whale Eubalaena glacialis. Prior to a December 2008 implementation of a mandatory, seasonally based vessel-speed rule (10 knots, 18.5 km h -1) along the eastern US seaboard, voluntary recommended speeds and routes were established. We used Automatic Identification System (AIS) data to evaluate and compare the compliance rates between the mandatory and voluntary measures to protect right whales in the southeast US critical habitat area off Florida and Georgia during the winters from 2005-06 to 2008-09. Vessel compliance was significantly higher under mandatory versus voluntary recommended speed restrictions, with compliance rates of 75 and 16%, respectively. Average vessel speeds were slower under mandatory speed restrictions (10.5 knots, 19.6 km h -1) compared to voluntary recommended speed restrictions (14.5 knots, 26.9 km h -1). Although vessels only slow down when mandated, they change their routing voluntarily. Compliance rates with voluntary recommended routes steadily increased during this period, from 43% prior to rulemaking, to 52% during the first year, 84% in the second year, and 96% in the final year of the study. Combining reduced speeds with recommended routes reduces the probability of right whale mortality from ships by 71.9% from the pre-implementation period. These results support long-term implementation of both vessel-speed reduction and restricted vessel routes for the survival and recovery of the North Atlantic right whale. © Inter-Research 2011.