16 articles in this issue
Secretariat NAMMCO
Christina H. Lockyer, Aleta A. Hohn, Roderick C. Hobbs, Robert E. A. Stewart
Introduction to Volume 10: Age estimation of marine mammals with a focus on monodontids
Aleta A Hohn, Christina Lockyer, Mario Acquarone
The workshop was a 2-day event organised immediately before the Society for Marine Mammalogy biennial conference in Tampa. NAMMCO funding enabled participation of 4 invited experts and also supported the organization and logistics associated with the work... see more
Christina Lockyer, Aleta A. Hohn, Roderick Hobbs, Robert EA Stewart
A workshop convened by C. Lockyer and A. A. Hohn to examine variation among readers in estimating beluga ages was held in Beaufort, North Carolina, US. Terms of Reference for the workshop included the following:1. Provide a guide as to acceptable le... see more
Fiona L. Read, Aleta A. Hohn, Christina H. Lockyer
This paper presents a critical review of methods for estimating absolute or relative age in marine mammals. Absolute age is achieved by counting growth layer groups (GLGs) in hard structures such as teeth, ear plugs, baleen, bones and claws. Relative age ... see more
Barbara E Stewart, Robert EA Stewart
The widely accepted method of determining ages of beluga is to count dentine growth layer groups (GLGs) in median, longitudinal sections of a tooth. It is essential to understand how these growth layers form and to consider developmental factors that can ... see more
Steven E Campana, Robert EA Stewart
Methods for confirming the accuracy of age determination methods are reasonably well established in fishes, but the millions of routine age determinations which take place every year require their own quality control protocols. In contrast, methods for en... see more
Cory JD Matthews, Steven H Ferguson
Isotopic time series from sequentially sampled growth layer groups (GLGs) in marine mammal teeth can be combined to build chronologies allowing assessment of isotopic variation in marine ecosystems. Synchronous recording of baseline isotopic variation acr... see more
Sinéad Murphy, Matthew Perrott, Jill McVee, Fiona L Read, Karin A Stockin
Knowledge of age structure and longevity (maximum age) are essential for modelling marine mammal population dynamics. Estimation of age in common dolphins (Delphinus spp.) is primarily based on counting Growth Layer Groups (GLGs) in the dentine of thin, d... see more
Christina H Lockyer, Gill T Braulik
The South Asian river dolphins (Platanista gangetica minor and P. g. gangetica) are endangered, geographically isolated, freshwater cetaceans. Accurate age estimation of individuals is an important aspect of population biology as it is used for calculatin... see more
Katherine Brill, Miriam Marmontel, Meghan Bolen-Richardson, Robert EA Stewart
Manatees are routinely aged by counting Growth Layer Groups (GLGs) in periotic bones (earbones). Manatee carcasses recovered in Florida between 1974 and 2010 provided age-estimation material for three readers and formed the base for a retrospective analys... see more
Carolina Loch, Donald R Schwass, Jules A Kieser, R Ewan Fordyce
Teeth are important elements in studies of modern and fossil Cetacea (whales, dolphins), providing information on feeding habits, estimations of age and phylogenetic relationships. The growth layer groups (GLGs) recorded in dentine have demonstrated appli... see more
Hikari Maeda, Tadafumi Kawamoto, Hidehiro Kato
We attempted to settle the potential problems of bias caused by too soft earplugs and poor formation of the growth layers in age readings of common minke whales. Thus, we examined the feasibility of a new technique of incorporating gelatin in order to col... see more
Morten Tange Olsen, Jooke Robbins, Martine Bérubé, Mary Beth Rew, Per J Palsbøll
This study examines the applicability of telomere length measurements by quantitative PCR as a tool for minimally invasive age determination of free-ranging cetaceans. We analysed telomere length in skin samples from 28 North Atlantic humpback whales... see more
Nynne H Nielsen, Gísli A. Víkingsson, Steen H. Hansen, Susanne Ditlevsen, Mads Peter Heide-Jørgensen
The ages of three species of cetaceans were estimated by counting the growth layer groups (GLG) and measuring the aspartic acid racemization rate (kAsp) by what is referred to as the Aspartic Acid Racemization (AAR) technique. Data on kAsp and the D/L rat... see more
Eva Garde, Mads F. Bertelsen, Susanne Ditlevsen, Mads Peter Heide-Jørgensen, Nynne H. Nielsen, Anne K. Frie, Droplaug Olafsdottir, Ursula Siebert, Steen H. Hansen
The aspartic acid racemization (AAR) technique has been applied for age estimation of humans and other mammals for more than four decades. In this study, eye lenses from 124 animals representing 25 mammalian species were collected and D/L ratios obtained ... see more