Collection planning for the next 100 years: What will we commit to save in zoos and aquariums?

OCCURRENCE OF GERM CELL NEOPLASIA IN MALE STRIPED BASS (MORONE SAXATILIS) UNDER HUMAN CARE IN A PUBLIC AQUARIUM: SURGICAL TREATMENT AND OUTCOME

The striped bass (Morone saxatilis) has been a fish species of special concern in Canada since its marked decline in the early 21st century in the St. Lawrence River. Individuals kept in public aquaria contribute to public education and could support conservation efforts through research. Over a 3-yr period, 12 male striped bass housed in a multispecies exhibit developed coelomic distension. The testes were enlarged (12/12), cystic (2/12), and heterogeneous (3/12) on coelomic ultrasound. Upon coeliotomy, enlarged (12/12), partially (4/12) or totally white discolored (6/12) testes were noted. These were associated with coelomic hemorrhage (8/12), effusion (3/12) or adhesions to surrounding organs (9/12). Orchiectomies were performed in all fish. Among these, seven fish survived 2 mon postsurgery, and four fish were still alive 900 d postsurgery. Germ cell neoplasia was diagnosed on histopathological examination in 9 of 12 individuals, but no abnormalities were found in the three other cases. Preventive orchiectomies were performed on the remaining six male striped bass in this exhibit. Germ cell neoplasms were present in two of these six fish. No anesthetic or surgical complications were noted; all six cases were alive 2 mon postsurgery and four of the fish survived 900 d postsurgery. Survival times were not significantly different between fish that underwent preventive or curative orchiectomy (P = 0.19). Although risk factors associated with the development of these gonadal tumors remain unknown, a genetic or environmental origin is suspected. Orchiectomy should be considered in suspected cases of testicular tumors.

Food-related substrate preference in juveniles seastar Echinaster (Othilia) brasiliensis (Müller & Troschel,1842) in captivity

There are only a few studies that describe the larval development of Echinaster or aspects on culture systems for the genus. For starfishes, the choice of suitable substrates has received special attention since it could influence the acid-base balance of the water, movement capacity and predation rate. The objective of this study was to evaluate the ideal food-related substrate for the rearing of juvenile Echinaster brasiliensis. A batch of fertilized eggs released in spontaneous spawning was collected and kept in a plankton-kreisel until metamorphosis. Data on preference of food-related substrate was recorded for 10 weeks from day 58 post-release. From release to 132 days old, arm length increased from 0.81 mm to 1.31 ± 0.03 mm. Considering the sudden increase in arm length (AL), it was estimated that feeding started around 40 days of age. Regarding food-related substrate preferences, biofilm grown on "rocks" showed a significant difference among other treatments, adding up to 50% of preference (p < .05). For sponge and biofilm from bio media, there was no statistical difference for the whole period. In this study, sponges showed to be the least preferred food-related substrate for post-settlement juveniles. Considering that Echinaster and other starfish are commonly maintained on a diet of collected or cultured sponges, difficulties in sourcing a ready supply throughout the year represent limitations to their sole use within commercial or laboratory-scale production. In this sense, the use of biofilm from biological media for the feeding of juvenile starfish is not yet reported in the literature and showed to be an easy and promising option.

Losing the forest for the tree? On the wisdom of subpopulation management

Animal habitats are changing around the world in many ways, presenting challenges to the survival of species. Zoo animal populations are also challenged by small population sizes and limited genetic diversity. Some ex situ populations are managed as subpopulations based on presumed subspecies or geographic locality and related concerns over genetic purity or taxonomic integrity. However, these decisions can accelerate the loss of genetic diversity and increase the likelihood of population extinction. Here I challenge the wisdom of subpopulation management, pointing out significant concerns in the literature with delineation of species, subspecies, and evolutionarily significant units. I also review literature demonstrating the value of gene flow for preserving adaptive potential, the often-misunderstood role of hybridization in evolution, and the likely overstated concerns about outbreeding depression, and preservation of local adaptations. I argue that the most effective way to manage animal populations for the long term be they in human care, in the wild, or if a captive population is being managed for reintroduction, is to manage for maximum genetic diversity rather than managing subpopulations focusing on taxonomic integrity, genetic purity, or geographic locale because selection in the future, rather than the past, will determine what genotypes and phenotypes are the most fit. Several case studies are presented to challenge the wisdom of subpopulation management and stimulate thinking about the preservation of genomes rather than species, subspecies, or lineages because those units evolved in habitats that are likely very different from those habitats today and in the future.

Zoo studies in primate physiology, health, and welfare

Researchers have been studying primates in zoos for more than half a century. There are numerous benefits to conducting research with zoo collections, such as access to a variety of species, ease of sample collection, and the potential to manipulate some research variables. While much of the primate research conducted in zoos is behavioral, there also is a tradition of research focused on reproduction and endocrinology, especially in North America. The contributions to this special issue exemplify how this tradition continues today through a collection of articles on basic and applied research on reproduction and using physiological measures of health and welfare that could be beneficial across primate taxa. As is the case for primatological research in zoos more broadly, the articles in this special issue reflect a taxonomic bias for great apes despite the high species diversity found across zoo collections. Given this bias as well as the threat of extinction faced by many species, there remains a pressing need to increase primatology in zoos through research dedicated to both conservation in the wild and wellbeing in human care.

Ex situ breeding programs benefit from science-based cooperative management

Science-based management confers a variety of benefits to wildlife populations that are cooperatively managed by zoos and aquariums, including those managed through the Association of Zoos and Aquariums. Briefly, when management strategies are successful, they result in reproductively robust populations that better retain genetic diversity and limit inbreeding than unmanaged populations. Although the benefits of demographic and genetic management have been well documented throughout both the scientific and popular literature, it has also been established that the majority of managed populations in zoos and aquariums are not meeting the minimum criteria believed to convey long-term biological viability. For most of these populations, an inability to meet viability criteria is not an inherent failure of how cooperative management is implemented. Furthermore, in recent years, we have perceived that the need to meet specific viability goals sometimes has obscured the benefits that these populations receive from rigorous, science-based management. To better clarify the conversation surrounding population viability in zoos and aquariums, we seek to decouple viability measures and how they predict population persistence from the benefits conferred to populations through science-based management. A primary goal of population management is to facilitate the persistence of priority species for longer than would be expected if no such management were implemented. Although current viability measures and future projections of viability are important tools for assessing the likelihood of population persistence, they are not indicators of which populations may most benefit from science-based management. Here, we review the history and purpose of applying science-based management to zoo and aquarium populations, describe measures of population viability and caution against confusing those measures of viability with population management goals or long-term population sustainability, and clearly articulate the benefits conferred to zoo and aquarium populations by science-based management.

A Census of Federally Regulated Big Cat Populations within the United States as of December 2020

No comprehensive assessment of the populations of big cats in federally regulated facilities in the United States is currently available. Concerns about big cat use are increasingly of strong public interest and the lack of data about their number and distribution has ramifications impacting zoological industry function, conservation programs, rescue work, and legislation. In this work a dataset has been compiled using publicly available USDA (United States Department of Agriculture) records and direct information requests. The resulting census was derived from the animal inventories listed on inspection records for all 2272 facilities with animal exhibition licenses. The total number of big cats in federally regulated facilities is on the order of 4100 animals and appears to be declining.

Breeding Centers, Private Ranches, and Genomics for Creating Sustainable Wildlife Populations

Human-induced changes to environments are causing species declines. Beyond preserving habitat (in situ), insurance (ex situ) populations are essential to prevent species extinctions. The Conservation Centers for Species Survival (C2S2) is leveraging space of breeding centers and private ranches to produce “source populations”—genetically diverse reservoirs that also support research and reintroductions. The initial focus is on four African antelopes. C2S2 has developed a program, the Source Population Alliance, that emphasizes animals living in spacious, naturalistic conditions in greater numbers than can be accommodated by urban zoos. Simulation modeling demonstrates how herds can rapidly increase population abundance and retain genetic diversity. Advances in genomics and resulting DNA data allow monitoring of genetic diversity and parentage as well as refined decision-making. This approach, neither pure in situ nor ex situ, but rather “sorta situ”, is an innovative way of linking public and private sector resources to ensure that endangered species survive.

Collection planning for the next 100 years: What will we commit to save in zoos and aquariums?

The "sustainability crisis" in zoos and aquariums has been a sobering reminder of how limited our resources are for maintaining viable populations of species threatened with extinction. This, combined with increasing concern among the public about the value of zoos and aquariums, suggests that the zoological profession should engage in a thorough re-examination of our guiding principles, philosophies, and practices with regard to collection planning at global, regional, and institutional scales. An analysis of AZA cooperative breeding programs reveals that in order to make these populations viable, many more founders and tens of thousands more spaces for animals, either in existing facilities or new ones, are necessary if we want to maintain all of the species that are covered by cooperative breeding programs currently. Regional zoological associations and their associated cooperative breeding programs must be more strategic and make more scientifically defensible decisions about which species to try and safeguard in zoos and aquariums. This would enable the zoological profession to give society a "Promise List" of species that we will commit to save from total extinction. Developing such a list will require a collaborative, inclusive process that transcends zoological regions. Regional association leaders, zoo & aquarium directors, and curators must make commitments to safeguard the species on the Promise List regardless of other interests. As our profession re-examines its philosophies and practices and finds ways to increase its capacity to provide refuge for species facing extinction in the wild, it may be possible to expand the Promise List.