Abstract
BackgroundThe objective of this study was to enhance removal of fishing gear from right whales (Eubalaena glacialis) at sea that evade disentanglement boat approaches. Titrated intra muscular injections to achieve sedation were undertaken on two free swimming right whales.Methodology/Principal FindingsFollowing initial trials with beached whales, a sedation protocol was developed for right whales. Mass was estimated from sighting and necropsy data from comparable right whales. Midazolam (0.01 to 0.025 mg/kg) was first given alone or with meperidine (0.17 to 0.25 mg/kg) either once or four times over two hours to whale #1102 by cantilevered pole syringe. In the last attempt on whale #1102 there appeared to be a mild effect in 20–30 minutes, with duration of less than 2 hours that included exhalation before the blowhole fully cleared the water. Boat avoidance, used as a measure of sedation depth, was not reduced. A second severely entangled animal in 2009, whale #3311, received midazolam (0.03 mg/kg) followed by butorphanol (0.03 mg/kg) an hour later, delivered ballistically. Two months later it was then given midazolam (0.07 mg/kg) and butorphanol (0.07 mg/kg) simultaneously. The next day both drugs at 0.1 mg/kg were given as a mixture in two darts 10 minutes apart. The first attempt on whale #3311 showed increased swimming speed and boat avoidance was observed after a further 20 minutes. The second attempt on whale #3311 showed respiration increasing mildly in frequency and decreasing in strength. The third attempt on whale #3311 gave a statistically significant increase in respiratory frequency an hour after injection, with increased swimming speed and marked reduction of boat evasion that enabled decisive cuts to entangling gear.Conclusions/SignificanceWe conclude that butorphanol and midazolam delivered ballistically in appropriate dosages and combinations may have merit in future refractory free swimming entangled right whale cases until other entanglement solutions are developed.
Highlights
Human impacts on North Atlantic right whales (Eubalaena glacialis) have largely erased potential population growth despite robust recent calving rates [1]
In 1999 an entangled right whale catalogued by the New England Aquarium as #2030 proved to be refractory to multiple disentanglement attempts. It was first sighted entangled on May 10 1999 with fishing gear stretched taught between both axillae that had stripped off large pieces of dorsal blubber and skin
A pole syringe based on a cantilevered pole system [4] was prepared and attempts to physically restrain the animal using a tail harness were made by PCCS and others
Summary
Human impacts on North Atlantic right whales (Eubalaena glacialis) have largely erased potential population growth despite robust recent calving rates [1]. Newer techniques developed in the 1980’s by the Provincetown Center for Coastal Studies, Provincetown, MA, USA, (PCCS) are being used to disentangle free-swimming entangled whales. In 1999 an entangled right whale catalogued by the New England Aquarium as #2030 (http://rwcatalog.neaq.org) proved to be refractory to multiple disentanglement attempts It was first sighted entangled on May 10 1999 with fishing gear stretched taught between both axillae that had stripped off large pieces of dorsal blubber and skin. Despite earlier predictions of the dire consequences of using immobilizing drugs in free swimming animals [8], an initial attempt to deliver sedatives to a right whale has been briefly reported [9]. Titrated intra muscular injections to achieve sedation were undertaken on two free swimming right whales
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