Sarah L Mesnick

• Doctor of Philosophy
• ecologist at National Oceanic and Atmospheric Administration

The behaviour of both humans and wildlife is central to the conservation of biodiversity because conservation requires human actions at multiple scales. In species with evidence of socially learned behaviour and culture, the juxtaposition of human and animal culture increases the complexity of human–wildlife interactions and their investigation but...

Culture—socially transmitted behaviours shared within a community—can influence animal populations' structure, vulnerability and resilience. Clans of sperm whales in the Eastern Tropical Pacific (ETP) exemplify the profound influence of culture on these dynamics and highlight the challenges of accounting for culture in conservation efforts. Globall...

Beaked whales (Ziphiidae), with 24 currently recognized species, are arguably the least known large animals on the planet, despite being widespread and at times abundant. Mesoplodon , with 16 currently recognized species, is by far the most speciose cetacean genus. Recent technological and taxonomic advances, long-term photographic-identification s...

The relationship between sexual selection and the diversity and rapid evolution of male genitalia has been well-documented across many animal taxa, while the morphological variability of female genitalia has received comparatively little attention. Female whales, dolphins, and porpoises possess unusual flaps, folds, and blind sacs in their vaginas,...

The world’s cetaceans (like most of biodiversity) are in crisis, and the need for well-informed conservation action has never been greater. Scientific advancements over the last few decades have provided much insight on the reproductive anatomy, physiology, and behavior of whales, dolphins, and porpoises. Our goal in this chapter is to link scienti...

In 2018, it was estimated that fewer than 20 of Mexico’s endemic vaquita porpoise Phocoena sinus remained, and the species was declining by 47% yr ⁻¹ . Entanglement in gillnets is the sole threat to the species, and since the last population size estimate, gillnetting has increased in the small area where most vaquitas remain—a 12 × 24 km area in t...

The Upper Gulf of California is a diverse and highly productive ecosystem supporting some of the most important fisheries in Mexico, yet a history of weak fisheries management and illegal fishing threaten the area’s biodiversity and undermine human well-being in the communities along its shores. The vaquita (Phocoena sinus) is endemic to these wate...

A key goal of conservation is to protect biodiversity by supporting the long-term persistence of viable, natural populations of wild species. Conservation practice has long been guided by genetic, ecological and demographic indicators of risk. Emerging evidence of animal culture across diverse taxa and its role as a driver of evolutionary diversifi...

Background The vaquita of Mexico is critically endangered, with a population less than 19 individuals in 2018. The population continues to decline and gillnet use continues in vaquita habitat. Methods Nine vaquita carcases were examined from 2016 to 2018 to establish cause of death. Concentrations of polychlorinated biphenyls (PCBs), DDTs and poly...

Asymmetric genitalia and lateralized mating behaviors occur in several taxa, yet whether asymmetric morphology in one sex correlates or coevolves with lateralized mating behavior in the other sex remains largely unexplored. While lateralized mating behaviors are taxonomically widespread, among mammals they are only known in the harbor porpoise (Pho...

A reply to Flessa et al. (2019)

Sociality—collective living—confers multiple advantages to oceanic dolphins, including enhanced foraging, predator avoidance, and alloparental care and may be particularly important in oceanic environments where prey is patchy and refuge nonexistent. This chapter covers broad aspects of the social lives of the delphinid community that inhabits the...

Understanding the rich social lives of animals benefits international conservation efforts

The vaquita porpoise (Phocoena sinus) is Mexico’s only endemic, and the world’s most endangered marine mammal. With a population of fewer than 30 individuals (Thomas et al. 2017; IUCN 2018), any delay in taking needed conservation actions will result in its extinction. A recent article (Manjarrez-Bringas et al. 2018) re-asserts, without providing a...

Acoustic communication is an important aspect of reproductive, foraging and social behaviours for many marine species. Northeast Pacific blue whales (Balaenoptera musculus) produce three different call types—A, B and D calls. All may be produced as singular calls, but A and B calls also occur in phrases to form songs. To evaluate the behavioural co...

Mitochondrial DNA has been heavily utilized in phylogeography studies for several decades. However, underlying patterns of demography and phylogeography may be misrepresented due to coalescence stochasticity, selection, variation in mutation rates, and cultural hitchhiking (linkage of genetic variation to culturally transmitted traits affecting fit...

Male genital diversification is likely the result of sexual selection. Female genital diversification may also result from sexual selection, although it is less well studied and understood. Female genitalia are complex among whales, dolphins, and porpoises, especially compared to other vertebrates. The evolutionary factors affecting the diversity o...

Complex foldings of the vaginal wall are unique to some cetaceans and artiodactyls and are of unknown function(s). The patterns of vaginal length and cumulative vaginal fold length were assessed in relation to body length and to each other in a phylogenetic context to derive insights into functionality. The reproductive tracts of 59 female cetacean...

Regression of cumulative vaginal fold length on number of vaginal folds. The non-phylogenetically controlled residuals of cumulative vaginal fold length on total body length were used. The solid black line indicates the line of best-fit from a phylogenetic reduced major axis regression (R2 = 0.113, t = 10.997, df = 19, P < 0.01). (TIF)

Counts and measurements of the specimens. Measurements were not scaled by body length. The U.S. state (or country for New Zealand) where each specimen stranded is listed. The median is listed in parentheses when it varies from the mean. (DOCX)

Poor communication between academic researchers and wildlife managers limits conservation progress and innovation. As a result, input from overlapping fields, such as animal behaviour, is underused in conservation management despite its demonstrated utility as a conservation tool and countless papers advocating its use. Communication and collaborat...

The interplay of natural selection and genetic drift, influenced by geographic isolation, mating systems, and population size, determines patterns of genetic diversity within species. The sperm whale provides an interesting example of a long-lived species with few geographic barriers to dispersal. Worldwide mtDNA diversity is relatively low, but hi...

Cetaceans exhibit vaginal folds, unusual protrusions of the vaginal wall into the vaginal lumen. Inconsistent terminology and a lack of anatomical landmarks in the literature have hindered comparative studies of the form and function of vaginal folds. Our objectives are to: 1) develop a standardized measurement protocol for the reproductive tracts...

The role of behavioral ecology in improving wildlife conservation and management has been the subject of much recent debate. We aim to answer two foundational questions about the current use of behavioral knowledge in conservation: 1. To what extent is behavioral knowledge used in wildlife conservation and management? 2. How does the use of behavio...

Fishing, farming and ranching provide opportunities for predators to prey on resources concentrated by humans, a behavior termed depredation. In the Gulf of Alaska, observations of sperm whales depredating on fish caught on demersal longline gear dates back to the 1970s, with reported incidents increasing in the mid-1990s. Sperm whale depredation p...

California sea lions (Zalophus californianus) are often viewed as a sentinel species whose health can be affected by prevailing oceanographic conditions and environmental quality. For this reason, it has become increasingly important to study natural stressors and anthropogenic impacts that can lead to diminished health and survival among individua...

Many severely depleted populations of baleen whales (Mysticeti) have exhibited clear signs of recovery whereas there are few examples in toothed whales (Odontoceti). We hypothesize that this difference is due, at least in part, to social and behavioural factors. Clearly, a part of the lack of resilience to exploitation is explained by odontocete li...

Pinnipeds vary in adult pelage color and pattern ranging from uniform white to black or brown and from solid coloration to subtle spotted or bold markings. Moreover, pelage color often differs by sex and age with neonates having radically different color and patterning from those of adults. We explored the functional significance of these patterns...

Sperm whale social groups can be assigned to vocal clans based on their production of codas, short stereotyped patterns of clicks. It is currently unclear whether genetic variation could account for these behavioural differences. We studied mitochondrial DNA (mtDNA) variation among sympatric vocal clans in the Pacific Ocean, using sequences extract...

In the eastern Gulf of Alaska, depredation of demersal longline fishing gear set for sablefish (Anoplopoma fimbria) by sperm whales (Physeter macrocephalus) has occurred since at least the mid‐1970s. In 1995, with the implementation of Individual Fishing Quotas, the season expanded from a 2 week derby style fishery to 8 months. This change allowed...

We use mitochondrial DNA (mtDNA) (400 bp), six microsatellites and 36 single-nucleotide polymorphisms (SNPs), 20 of which were linked, to investigate population structure of sperm whales (Physeter macrocephalus) in the eastern and central North Pacific. SNP markers, reproducible across technologies and laboratories, are ideal for long-term studies...

Background: Ocean pollution affects marine organisms and ecosystems as well as humans. The International Oceanographic Commission recommends for ocean health monitoring programs to investigate the presence of marine contaminants and the health of threatened species and to include multiple and early-warning biomarker approaches.

Ocean pollution affects marine organisms and ecosystems as well as humans. The International Oceanographic Commission recommends ocean health monitoring programs to investigate the presence of marine contaminants and the health of threatened species and the use of multiple and early-warning biomarker approaches. We explored the hypothesis that biom...

Microsatellite allele data have long been plagued by size shifts that can at best make it difficult to accurately assign genotypes to allele products, and at worse can cause whole batches of data from different instruments, dates or laboratories to be incorrectly assigned. Although modern genotyping technology (capillary electrophoresis) has overco...

Blue whale Balaenoptera musculus songs can be divided into at least 10 types worldwide, each type retaining the same units and similar phrasing over decades, unlike humpback whale song which changes substantially from year to year. Historical acoustic recordings dating back as far as the 1960s were examined, measuring the tonal frequencies of 1000s...

The mechanisms that determine population structure in highly mobile marine species are poorly understood, but useful towards understanding the evolution of diversity, and essential for effective conservation and management. In this study, we compare putative sperm whale populations located in the Gulf of Mexico, western North Atlantic, Mediterranea...

We investigate the phylogeography of California (Zalophus californianus) and Galápagos (Z. wollebaeki) sea lions and describe within-population structure for the California sea lion based on mitochondrial DNA. Fifty control-region haplotypes were found, 41 from Z. californianus and 9 from Z. wollebaeki, with three fixed differences between the two...

We report the characterization of 18 new single nucleotide polymorphism (SNP) markers for an endangered species, the sperm whale (Physeter macrocephalus), developed using a targeted gene approach. SNP markers were derived from autosomal regions of the genome using primers originally characterized for genome mapping in other mammals. These SNP marke...

Blue whale songs provide a new means for characterizing blue whale population structure worldwide. These songs are divided into nine regional types, which maintain a stable character. Five of the nine song types have been recorded over time spans greater than 30 years showing no significant change in character. We suggest that distinct differences...

Sequence polymorphism of homologues ZFX and ZFY, in a 604-base pair exon region, was examined in 10 known males and 10 known females across seven cetacean families and used to design a simple, highly sensitive and widely applicable fluorescent 5' exonuclease assay for gender determination in cetaceans. Multiplex amplification, cloning, and sequenci...

The trophic position and the predator–prey relationship between the sperm whale Physeter macrocephalus and the jumbo squid Dosidicus gigas were examined by measuring stable isotope ratios of carbon and nitrogen. Skin samples of sperm whales and muscle samples of small and large jumbo squid were collected between 1996 and 1999 in the Gulf of Califor...

A bstract We offer the first report for a cetacean of geographical variation in mating system based in morphology. Analysis of samples from 1,678 male spinner dolphins from the eastern Pacific revealed that testis + epididymis weight was greater (to 1,354 g) in the whitebelly form of the species than in the eastern form (to 843 g). Sexual dimorphis...

A bstract In October 1997 we observed a herd of approximately 35 killer whales ( Orcinus orca ) attack a pod of nine sperm whales ( Physeter macrocephalus ) 130 km off the coast of central California. During the four hours we watched, adult female killer whales, including some with calves, attacked in waves of four to five animals in what was appar...

Results of genetic analyses show that social groups of female and immature sperm whales are comprised of multiple matrilines as evidenced by the presence of multiple mitochondrial (maternally inherited) control region haplotypes. These data suggest: (1) a social environment in which the transmission of cultural information, such as vocal dialects,...

The frequency of occurrence of naturally sloughed skin was investigated to verify the feasibility of this method to study blue whale genetics off Baja California. Sloughed skin was recorded in 97% of 337 surfacing intervals with blue whales, Balaenoptera musculus, along the Baja California peninsula, Mexico. No significant difference (P > 0.05) was...

H. Whitehead ([1][1]) explains low nucleotide diversities in the control region of the mitochondrial DNA (mtDNA) of matrilineal whale species with the use of a theory developed for molecular “hitchhiking,” in which diversity at a neutral locus is reduced by selection at a linked locus. As

In a comparative review of mateship alliances, Mesnick (this volume) argues that one benefit to females of forming a heterosexual pair-bond is reduction in risk of sexual aggression from other males. Several subsidiary hypotheses follow from this “bodyguard hypothesis,” including (1) that females may be especially attracted to large and/or dominant...

For many species of animals, mating serves more than a procreative function, and much more than gametes are exchanged between partners (Wilson, 1978). Females are expected to be discriminating among males on the basis of a wide variety of properties, including resources that males actually or potentially hold, their abilities as parents, and their...

During mating attempts by males, female elaphant seals, Mirounga angustirostris, are sometimes injured or killed as they return to sea at the end of lactation. We tested two predictions from the general hypothesis that females behave in a way that reduces the possibility of injury or death from sexual encounters with males: 1) departing females att...

Adult female mortality in Mirounga angustirostris was monitored at Ano Nuevo, California. Only 17 female deaths were recorded over a 20 yr period; 11 were caused by traumatic injuries inflicted by males during mating attempts as the females departed harems for the sea at the end of lactation. The probability of a female being killed by a male durin...

Adult female mortality of northern elephant seals, Mirounga angustirostris, was monitored daily throughout the breeding season and weekly during the non-breeding season at Ano Nuevo, California, during the period 1968 to 1987. Behavioral observation and necropsy findings were collected and circumstantial evidence was compiled to determine the cause...