DOI: 10.5061/dryad.np5hqc01m
title: Extreme longevity may be the rule not the exception in Balaenid whales

description: We fit ongoing 40+ year mark-recapture databases from the thriving
 southern right whale (SRW); Eubalaena australis, and highly endangered
 North Atlantic right whale (NARW); Eubalaena glacialis, to candidate
 survival models to estimate their lifespans. The median lifespan for SRW
 was 73.4 years, with 10% of individuals surviving past 131.8 years. NARW
 lifespans were likely anthropogenically shortened, with a median lifespan
 of just 22.3 years, and 10% of individuals living past 47.2 years. In the
 context of extreme longevity recently documented in other whale species,
 we suggest all balaenid and perhaps most great whales have an unrecognized
 potential for great longevity that has been masked by the demographic
 disruptions of industrial whaling. This unrecognized longevity has
 considerable implications for the basic biology and conservation of
 whales.
description: Mark-Resight Data. From 1979
 to 2021, SRW were annually surveyed in October by helicopter between
 Nature’s Valley and Muizenberg, False Bay along the south coast of South
 Africa. All individuals sighted were noted, and callosity patterns of
 females with calves were carefully photographed for identification
 purposes. Photos were compared to a long-running photo-identification
 catalog and matched. Over the 42-year period, this resulted in a
 mark-recapture data set of 2476 unique females, of which 139 have known
 birth years. Survey methods and photo identification details are available
 in (1) and (2). Mark-recapture records for NARW spanned
 approximately the same period. Starting in the mid-1970s a photographic
 catalog of all NARWs began, and the observation effort intensified and
 became more organized in the 1980s. Unlike the SRW mark-recapture data,
 observations for NARW are assembled by a large group of collaborating
 scientists working across the species’ entire range. The photographic
 catalog and data are maintained by the North Atlantic Right Whale
 Consortium, which made the mark-recapture records of females available for
 this analysis. All NARW encountered by members of the consortium at any
 time during the year and in any geographic region, were photographed.
 These photos are compared to the master catalog maintained by the
 consortium and matched to individuals on file. This much more intense
 survey effort results in many observations per year for most individuals.
 Here, we analyze only observations from females. 
 
 Following (3), these multiple detections per year were reduced so
 that the detection period was simply annual, and individuals in a given
 year were either detected (1) or not detected (0). In total, this data set
 spanned 1974 to 2020 and included 328 unique females, of which 205 had
 known birth years. Further details on data collection and the
 photo-identification catalog can be found in (3) and (4).
 One notable difference between the NARW and SRW mark-recapture
 time series is the size and trajectory of the respective populations that
 were observed. As the SRW population is large and growing, new individuals
 have steadily been incorporated into the SRW dataset since the study’s
 inception, most of which do not have known birth years. Individuals with
 unknown birth years detected after 1990 also have short observation
 periods (relative to lifespan), and thus provide minimal information about
 the shape of the survival function. Therefore, we limited the analysis of
 SRW data to individuals with known birth years or individuals first
 observed (but without a known birth year) prior to 1985. The resulting SRW
 dataset included 361 individuals, 139 with known birth years and 222 with
 unknown birth years but observation periods &gt;35 years. Similar
 subsampling was not required for NARW because most of the individuals in
 the dataset have known birth years and nearly all individuals added to the
 mark-recapture database without known birth years were added before 1990
 and thus have long observation periods relative to their lifespans. Both
 the SRW and NARW mark-recapture datasets have had relatively steady
 observation efforts over their respective time series with no missing
 observation years. Thus the analyzed samples for SRW and NARW were of
 similar size, length, and quality and, as they both included hundreds of
 individuals, were more than adequate for estimation of
 longevity. References 
 P. B. Best, A. Branda ̃o, D. S.
 Butterworth, <em>J. Cetacean Res. Manage.</em> pp. 161–169
 (2001). E. Vermeulen, T. Thavar,
 M. Glarou, A. Ganswindt, F. Christiansen, <em>Scientific
 Reports</em> 13, 3228 (2023).
 R. M. Pace, P. J. Corkeron, S. D. Kraus,
 <em>Ecology and Evolution</em> 7, 8730 (2017).
 R. D. Kenney, North Atlantic Right Whale
 Consortium Reference Document 1 (2010).
description: # Extreme longevity may be the rule not the exception in Balaenid whales
 [https://doi.org/10.5061/dryad.np5hqc01m](https://doi.org/10.5061/dryad.np5hqc01m) The data contains annual sightings (0: not observed that year; or 1: observed that year) for uniquely marked right whales. Sighting records are as early as 1936 to the present, but most observations were made after 1975. ## Description of the data and file structure Each row contains the sightings history for a unique whale. Column 1 "ID" contains the whale ID Column 2 "Birth": Year of birth, if known. If unknown, contains a 0. Column 3 "Death": Year of death, if known. If unknown, contains a 0. All remaining columns: Observations years. Contains a 1 if the animal in that row was seen, contains a 0 if the animal in that row was not seen. ## Sharing/Access information NA ## Code/Software NA