Clinical assessment and postrelease monitoring of 11 mass stranded dolphins on Cape Cod, Massachusetts

Abstract

The health, postrelease movements, and behavior of mass stranded Atlantic white‐sided dolphins (Lagenorhynchus acutus) and short‐beaked common dolphins (Delphinus delphis) from Cape Cod, Massachusetts, were evaluated. Health was assessed through physical examination and blood analysis. Eleven dolphins (eight white‐sided dolphins and three common dolphins) were relocated, outfitted with satellite transmitters, and released during seven mass stranding events. Five transmitters recorded only location, and six also included a time‐depth recorder. Transmission duration ranged from 8 h to 218 d, with a mean of 117 d (median = 118 d, SD = 82 d), after release. All dolphins demonstrated extensive movement throughout the Gulf of Maine. The distribution of tagged dolphins was considered normal based on comparisons with published data for these species. Excluding the dolphin that transmitted for only 8 h, mean minimum speeds for individual dolphins ranged from 3.4 to 6.6 km/h; overall mean for all dolphins was 5.4 km/h (SD = 0.9 km/h). The five dolphins with time‐depth recorders had mean dive depths of 8.6–40.3 m and mean dive durations of 46–296 s. Hematologic and biochemical data revealed only minor abnormalities. Data suggest that at least 10 of the 11 dolphins were likely successfully reintroduced into the wild.

Movements and Dive Patterns of Short-Finned Pilot Whales (Globicephala macrorhynchus) Released from a Mass Stranding in the Florida Keys

“…Sampson et al (2012) have demonstrated the utility of assessing health on the beach to decide if individual dolphins are releasable, and they have tested their judgments through post-release monitoring involving satellite-linked tracking. Our findings from at least one of the two pilot whales released from the stranding site after on-site health assessment suggest that the animal survived and returned to patterns typical of pilot whales.…”

“…In two such cases, marked individuals subsequently restranded at other locations, up to several weeks post-release (Fehring & Wells, 1976;Irvine et al, 1979). Sampson et al (2012) evaluated the health of stranded Atlantic white-sided dolphins (Lagenorhynchus acutus) and short-beaked common dolphins (Delphinus delphis) from mass strandings on Cape Cod, Massachusetts, and then performed satellite-linked follow-up tracking. They determined that it is reasonable to expect that at least some mass-stranded dolphins in stable physical and physiologic condition can be relocated and released on the same day as stranding, and that they will resume behavior and habitat use that is typical of the species.…”

“…Recent findings by Sampson et al (2012) suggest one possible way to reduce the potential impact of human interventions on released cetaceans. Specifically, medical diagnoses on the beach that lead to immediate release should, in some cases, benefit the animals medically by reducing the risks of stress, illness, and injury from rehabilitation, and reduce exposure to humans and unnatural situations.…”

Biological Data of Pygmy Killer Whale (Feresa attenuata) from a Mass Stranding in New Caledonia (South Pacific) Associated with Hurricane Jim in 2006

“…As it was not found restranded in the days following, and given its better health status compared to animal #2, we can hypothesize that it may have survived. This hypothesis is supported by the example of the false killer whales in Florida and recent demonstrations through satellite tracking and monitoring of the successful release of stranded animals in Australia and the U.S., in spite of their poor conditions (Gales et al, 2012;Sampson et al, 2012). The withdrawal of animal #2 on 1 February was artificial, but we can hypothesize that its natural death would have had the same consequence of releasing animal #1.…”

Assessing the neurotoxicological risk of methylmercury exposure for beluga whales (delphinapterus leucas) harvested in the Mackenzie Delta Estuary.

“…Behavioural studies have also been used to complement physical examinations and blood analyses to assess the fitness o f stranded dolphins (Sampson et al, 2012). Beluga whale behaviour is particularly difficult to document in the wild because beluga whales spend approximately 85 % of their time below water (Kingsley et al, 2001 This study documented one case in which a beluga whale was observed to behave very unusually after it was harpooned.…”