An example why captive dolphin studies should not be used to make conservation decisions

The marine mammal research listserve MARMAM has just posted a paper appearing in the journal Aquatic Mammals (Rechsteiner, E. et al. 2013. Seasonal resting metabolic rate and food intake of captive Pacific white-sided dolphins (Lagenorhynchus obliquidens). Aquatic Mammals 39(3) 241-252) which  concludes:

"Our estimates of resting metabolic rates and relative changes in total energy intake can be used to parameterize bioenergetic models needed to estimate the ecological impacts and energetic requirements of Pacific white-sided dolphins in the wild, which will have conservation implications."

The partner paper in a different journal (Rechsteiner, E. et al. 2013. Energy requirements of Pacific white-sided dolphins (Lagenorhynchus obliquidens) as predicted by a bioenergetic model. Journal of Mammalogy. 94(4) 820-832) also says that the study has useful data for conservation.

But if you look in the MS thesis from which this paper is derived you find:

“The extent to which my results are representative of dolphins in the wild is uncertain given that the behaviours and activities of dolphins in aquaria do not necessarily mimic those of wild dolphins. I am also uncertain whether the occasional heating of the water in the dolphin habitat at the Vancouver Aquarium influenced my results, and I recognize that my conclusions are limited by the small number of animals studied.

Despite such shortcomings, the data collected from the three individuals represent the most comprehensive energetics study conducted to date with Pacific white-sided dolphins, and the only cetacean energetics study that has spanned multiple seasons and examined both resting metabolic rates and total calories ingested”

(p. 49 in Rechsteiner, E. 2013. Testing metabolism, energetics, and seasonal distribution of Pacific white-sided dolphins.  MS thesis. University of British Columbia).

Throughout the papers and thesis are statements about how these data can be used to inform management, in particular issues relating to how many fish dolphins consume and therefore potential conflicts with fisheries.

My first thoughts when I read this were this could immediately be used by certain bodies to try to justify culls of dolphins. Japan already has a large take of Pacific white-sided dolphins (86 dolphins were hunted in the 2010-2011 season; http://en.elsaenc.net/report/publiccomment/) and could use this study to justify that by taking more dolphins they are protecting fisheries.

But really how representative of the thermoregulation and energy use of wild populations are data from 3 individuals that live in a heated pool (in contrast sea surface temperatures in the winter off of British Columbia drop to 3^oC), who move limited distances. Pacific-white sided dolphins can move 10s of kilometers in a day, and importantly, are known to migrate, including southwards to warmer waters of Southern California during the winter (e.g. Leatherwood et al.  1988.  Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Artic Waters. New York:  Dover Publication). So how representative of wild populations really is this study? Probably not very, yet conservation decisions could be made on this study, which the authors appear to be encouraging, but how many managers will read the caveats?

One of the problems with captive cetacean facilities is that they are so desperate to suggest that they have value in the modern world, especially to conservation, that they fiercely push and publicize the few studies that they produce. However, if managers do use these studies they are likely making the wrong decisions as the behavior and ecology of captive animals is vastly different to wild animals. For example, using studies on the sound sensitivity of captive cetaceans (which may suffer hearing loss due to high noise exposure and medical treatments) to predict the impacts on wild populations have wildly underestimates the sensitivity, and therefore underestimate man-made noise impacts on, wild cetaceans (Wright, A.J. et al. 2009. Urging cautious policy applications of captive research data is not the same as rejecting those data. Marine Pollution Bulletin 58: 314-316; Parsons, E.C.M. et al. 2008. Navy sonar and cetaceans: just how much does the gun need to smoke before we act? Marine Pollution Bulletin 56: 1248-1257).

So, my take home message is, studies on captive whales and dolphins have limited applicability to the actual ecology and behavior of wild cetaceans, and as a such using these studies to make conservation, management and policy decisions is inappropriate and possibly even detrimental.