Search

Recent scientific developments have made possible something that would once—not long ago—have seemed out of a science fiction film: the creation of a human and non-human chimaera with human brain cells and their eventual birth. This has posed novel challenges for lawmakers. Laws have been established to allow for the creation of these entities; the challenge now is to define their legal status. Such chimaeras are neither entirely animal nor entirely human, but unlike other chimeric creatures, they share a feature with humans that has long been considered the basis of the special legal status afforded to the human person: human brain cells. This feature is unlikely to prove sufficient to replicate the human brain. Likewise, it is improbable that these creatures will reach the same levels of autonomous thinking and consciousness as humans. Still, such enhanced chimaeras might acquire capacities that distinguish them from other animals. As such, a special legal status must be created to accommodate their specific characteristics. This paper will analyse the legal status that should be granted to these chimeric entities in light of the existing laws. [ABSTRACT FROM AUTHOR]

In this review of the behavioural patterns of chondrichthyan fishes, we have strived to produce a comprehensive catalogue of events and states and develop standardized terminology. Hence, actions that are slightly different, will be pooled under inclusive titles. Those used by different investigators are included in quotations within the textual descriptions of the motor patterns. This standardized ethogram will ideally lead to an increase in inter-observer reliability, giving researchers more confidence when reading colleagues' papers that report behaviours that appear similar to theirs despite being described for different species. The descriptions are presented under the following categories: (1) maintenance (2) courtship (3) filter feeding (4) scavenging (5) predation (6) sociality (7) aggression and (8) defence. The many actions are illustrated by line drawings and photographs in composite figures with an attempt to provide an example of each action for a chimaera, shark, and ray. The diversity of patterns is evident from this ethogram, consistent with observation that the brain-to-body mass ratios of cartilaginous fishes are greater than a third of the bird species and greater than those for some mammalian species. The major impetus for assembling this ethogram is to demonstrate the diversity of behaviours exhibited by members of the Chondrichthyes and to dispel the apocryphal belief that members of this taxon are 'simple feeding machines'. [ABSTRACT FROM AUTHOR]

Sharks, skates, rays and chimaeras (chondrichthyans) are of high conservation concern; especially obligate freshwater chondrichthyans, given their restricted ranges, proximity to humans, and threatened habitat. The biological traits that increase chondrichthyan susceptibility to extinction are well known. Less attention has been put on the human determinants of chondrichthyan conservation status. Socio-economic development, scientific research, and exploitation affect natural resource management and conservation. We assessed the relationship between these factors and chondrichthyan conservation. We ran generalized linear models with number of Threatened (THR), Least Concern (LC), and Data Deficient chondrichthyans as dependent variables, and indicators of socio-economic development (governance, human security, human development, and corruption indices), scientific research (number of papers on chondrichthyans), and exploitation (total, industrial, and foreign catch of chondrichthyans), as independent variables. Human density instead of exploitation was a predictor for obligate freshwater chondrichthyans. Socio-economic development (regardless of the index used) and scientific research were associated to desirable conservation status, such as low THR and high LC, for both marine and obligate freshwater species. Exploitation and human density (for obligate freshwater chondrichthyans) were associated to negative conservation status, i.e. high THR and low LC. Current human density projections translated into a 69% decrease in obligate freshwater chondrichthyans LC by 2050. Development produces desirable conservation status for chondrichthyans, but resource overconsumption must be reduced. Scientific research appears to assist sustainable use of chondrichthyan resources, and should be promoted in developing countries. Assessment and conservation of obligate freshwater chondrichthyans, and freshwater biota in general, must be pursued with urgency. [ABSTRACT FROM AUTHOR]

The objective of this paper was to characterize bycatch in an experimental fishery for Patagonian toothfish in Ecuador during 2017–2021. Diversity was analysed using Shannon, Margalef, Simpson, and Dominance indices. Bycatch representativity was calculated as the difference percentage between the target catch and non-target, in weight. The bycatch comprised 51 taxa and was composed primarily of fish. In addition, 12 species of pelagic habits (i.e. fishes and sharks) were also captured during the deployment/retrieval of fishing gear. The most frequent species (by number of individuals) were chimaeras (Hydrolagus melanophasma), grenadiers (Antimora rostrata , Coryphaenoides delsolari , and Coryphaenoides armatus), and sharks (Etmopterus granulosus and Centroscymnus owstonii). The diversity was medium low, according to the Shannon indices (0.5–1.8), with a negative trend for dominance and a positive trend for equitability. [ABSTRACT FROM AUTHOR]

Species diversity assessments are an important step to evaluate the conservation status of a community, both in marine and terrestrial ecosystems. These assessments are pivotal if related to both, the constant increase of human pressure on ecosystems and the anthropogenic climate change occurring nowadays. Sharks and rays are globally threatened, and the situation is particularly alarming in the Mediterranean Sea where more than 50% of species are listed at risk of extinction by the International Union for Conservation of Nature (IUCN). In this paper, we revise and discuss the chondrichthyan species richness of the Mediterranean and the Black Sea. Through an accurate review of published taxonomic studies, historical data on species occurrence, analyses of scientific survey data and biodiversity databases and other scientific papers, we produced a revised list of species whose presence in the Mediterranean Sea is confirmed or highly probable and discussed on current taxonomic and occurrence disputes on the species that are instead rarer or claimed to be locally extinct. We listed a total of 88 species, representing 30 families and 48 genera that are currently present in the Mediterranean and the Black Sea. This number includes 48 shark species, 38 batoids, and 2 chimaeras. The review represents a reference for future conservation assessments of cartilaginous fish in the region and a guide for decision-makers when promoting the sustainable exploitation of fisheries resource within an ecosystem-based framework. This paper can help to set a baseline of the Mediterranean species and thus resolve some uncertainties regarding their conservation status, explaining the reasons for their prolonged absence in the reports. Indeed, failure to record over time may not be due to grubbing up, but because after careful review this species was not really part of the Mediterranean fauna. [ABSTRACT FROM AUTHOR]

Species diversity assessments are an important step to evaluate the conservation status of a community, both in marine and terrestrial ecosystems. These assessments are pivotal if related to both, the constant increase of human pressure on ecosystems and the anthropogenic climate change occurring nowadays. Sharks and rays are globally threatened, and the situation is particularly alarming in the Mediterranean Sea where more than 50% of species are listed at risk of extinction by the International Union for Conservation of Nature (IUCN). In this paper, we revise and discuss the chondrichthyan species richness of the Mediterranean and the Black Sea. Through an accurate review of published taxonomic studies, historical data on species occurrence, analyses of scientific survey data and biodiversity databases and other scientific papers, we produced a revised list of species whose presence in the Mediterranean Sea is confirmed or highly probable and discussed on current taxonomic and occurrence disputes on the species that are instead rarer or claimed to be locally extinct. We listed a total of 88 species, representing 30 families and 48 genera that are currently present in the Mediterranean and the Black Sea. This number includes 48 shark species, 38 batoids, and 2 chimaeras. The review represents a reference for future conservation assessments of cartilaginous fish in the region and a guide for decision-makers when promoting the sustainable exploitation of fisheries resource within an ecosystem-based framework. This paper can help to set a baseline of the Mediterranean species and thus resolve some uncertainties regarding their conservation status, explaining the reasons for their prolonged absence in the reports. Indeed, failure to record over time may not be due to grubbing up, but because after careful review this species was not really part of the Mediterranean fauna.

Copyright of Cybium: International Journal of Ichthyology is the property of Societe Francaise d'Ichtyologie (SFI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Size measurements are crucial for studies on the growth, maturation, maximum size, and population structure of cartilaginous fishes. However, researchers use a variety of measurement techniques even when working on the same species. Accurate comparison of results among studies is only possible if the measurement technique used is adequately defined and, if different techniques are used, a conversion equation can be derived. These conditions have not always been met, leading to invalid comparisons and incorrect conclusions. This paper reviews methods used for measuring chondrichthyans, and summarises the variety of constraints that influence the choice of a measurement technique. Estimates of the variability present in some measurement techniques are derived for shortfin mako shark, Isurus oxyrinchus, porbeagle shark, Lamna nasus, blue shark, Prionace glauca, Antarctic thorny skate, Amblyraja georgiana, and Pacific electric ray, Torpedo californica. Total length measured with the tail in the natural position (sharks) and disc widths (batoids) have higher variability than other methods, and are not recommended. Instead, the longest longitudinal axis should be measured where possible and practical; i.e., flexed total length for sharks, total length for batoids (excluding suborder Myliobatoidei), pelvic length for batoids of the suborder Myliobatoidei, and chimaera length (snout to posterior end of supracaudal fin) for chimaeroids (except for Callorhinchus, for which fork length should be measured from the anterior edge of the snout protuberance). Straight-line measurements are preferred to measurements over the curve of the body. Importantly, measurement methods must be clearly defined, giving information on the anterior reference point, the posterior reference point, and how the measurement was made between these two. Measurements using at least two different methods are recommended on at least a subsample of the fish in order to develop conversion regression relationships. [ABSTRACT FROM AUTHOR]

The rich variety of biological forms and behaviours results from one evolutionary history on Earth, via frozen accidents and selection in specific environments. This ubiquitous baggage in natural, familiar model species obscures the plasticity and swarm intelligence of cellular collectives. Significant gaps exist in our understanding of the origin of anatomical novelty, of the relationship between genome and form, and of strategies for control of large-scale structure and function in regenerative medicine and bioengineering. Analysis of living forms that have never existed before is necessary to reveal deep design principles of life as it can be. We briefly review existing examples of chimaeras, cyborgs, hybrots and other beings along the spectrum containing evolved and designed systems. To drive experimental progress in multicellular synthetic morphology, we propose teleonomic (goal-seeking, problem-solving) behaviour in diverse problem spaces as a powerful invariant across possible beings regardless of composition or origin. Cybernetic perspectives on chimaeric morphogenesis erase artificial distinctions established by past limitations of technology and imagination. We suggest that a multi-scale competency architecture facilitates evolution of robust problem-solving, living machines. Creation and analysis of novel living forms will be an essential testbed for the emerging field of diverse intelligence, with numerous implications across regenerative medicine, robotics and ethics. [ABSTRACT FROM AUTHOR]

Chondrichthyes (including sharks, rays, and chimaeras) are a class of jawed cartilaginous fishes (with skeletons composed primarily of cartilage), with major relevance to the marine ecosystems and to humanity. However, cartilaginous fishes are facing various threatens, inflicting abrupt declines in their populations. Thus, critical assessment of available molecular genetic variation, particularly retrieved from Chondrichthyans' transcriptomic analyses, represents a major resource to foster genomics research in this ancient group of vertebrate species. Briefly, RNA-Seq involves the sequencing of RNA strands present on a target tissue, which can assist genome annotation and elucidate genetic features on species without a sequenced genome. The resulting information can unravel responses of an individual to environmental changes, evolutionary processes, and support the development of biomarkers. We scrutinized more than 800 RNA-Seq entries publicly available, and reviewed more than one decade of available transcriptomic knowledge in chondrichthyans. We conclude that chondrichthyans' transcriptomics is a subject in early development, since not all the potential of this technology has been fully explored, namely their use to prospectively preserve these endangered species. Yet, the transcriptomic database provided findings on the vertebrates' evolution, chondrichthyans' physiology, morphology, and their biomedical potential, a trend likely to expand further in the future. [ABSTRACT FROM AUTHOR]

Copyright of Cybium: International Journal of Ichthyology is the property of Societe Francaise d'Ichtyologie (SFI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Washed-up chondrichthyan egg cases were collected along three different sandy beaches around Plettenberg Bay, South Africa, between April 2016 and March 2017. GPS location was recorded upon collection, and, after being soaked in fresh water for 12 hours, egg cases were identified to species level. Additionally, boreholes, damage, biofouling and state of the hatchling slit were recorded. The hatching success of each egg case was inferred from these factors. Over the year, 6 996 egg cases of nine species were collected. Egg cases of the tiger catshark Halaelurus natalensis had the highest hatching rate at 70%. Egg cases of the leopard catshark Poroderma pantherinum had the highest predation rate at 57%. Season had no significant effect either on overall egg-case counts or on per-species counts. Location, however, significantly affected the overall egg-case counts, as well as per-species counts, with the exceptions of H. natalensis and the St Joseph Callorhinchus capensis. The results of this study provide insight into chondrichthyan species occurrence and spatial variation along a section of the Garden Route in the Western Cape Province and can act as a baseline for future research. [ABSTRACT FROM AUTHOR]

In cooperation with NMFS Northwest Fisheries Science Center and Southwest Fisheries Science Center, Santa Cruz Lab, researchers from the Pacific Shark Research Center/Moss Landing Marine Laboratories have been participating and assisting in groundfish surveys since 2002. Vertebrae for age and growth estimation, reproductive tracts, and/or stomachs for feeding analyses were collected from over 5,000 specimens. Studies on the age and growth of the roughtail (Bathyraja trachura) and sandpaper (Bathyraja kincaidii) skates were completed, with one paper having been published and another having been accepted for publication. Age and growth studies for several other commonly encountered chondrichthyans are continuing. Studies on the reproductive biology of the big (Raja binoculata), California (Raja inornata), longnose (Raja rhina), roughtail, and sandpaper skates, and the white-spotted chimaera (Hydrolagus colliei) were completed and manuscripts are currently being prepared for publication. A study on the reproductive biology of three deepsea catsharks (Scyliorhinidae) was completed, with two publications currently in press. Dietary studies were completed for four species, the big, California (Raja inornata), longnose, and sandpaper skates, with analyses continuing for several other species. Research results for this project have resulted in two Masters Theses, ten publications, and 18 presentations at seven conferences. This project funded two California Sea Grant trainees both of whom worked on projects that served as their Masters Theses.

Using the last taxonomic review of chondrichthyans of the world, we selected the species distributed in the north‐western Atlantic Ocean (NWA) and compared it with the available published literature related to the class Chondrichthyes in the Venezuelan exclusive economic zone. We also revised information from worldwide databases such as: FAO (NWA‐31 area), GBIF, iSpecies, IUCN and OBIS, as well as available museum collection databases. The taxonomic validity was checked using the Catalogue of Fishes of the California Academy of Sciences and recent references. The past published Venezuelan lists of chondrichthyans combined included nine orders, 30 families and 108 species. The updated list with 12 orders, 36 families and 122 species increased by three new orders, six families, three shark genera, nine shark species (one replacing another species), one chimaera genus, two chimaera species, three batoid genera and six batoid species (two replacing other species). Four holotype specimens (two sharks and two rays) are deposited in Venezuelan Museums. Most of the species have an IUCN conservation status, including four species catalogued as Critically Endangered, six as Endangered and 18 species as Vulnerable. Deep‐sea fisheries, scientific exploration and taxonomic/genetic revisions might add future increments to the Venezuelan chondrichthyan list. [ABSTRACT FROM AUTHOR]

The checklist presented in this study includes the latest taxonomic and systematic modifications and updates (early 2018) for the Chondrichthyes that inhabit the Exclusive Economic Zone (EEZ) of Mexico. The list is based on a literature review of field-specific books, scientific publications and database information from collections and museums worldwide available online such as, the Ocean Biogeographic Information System (OBIS), Global Biodiversity Information Facility (GBIF), Encyclopedia of Life (EOL), iSpecies, FishBase and the National Biodiversity Information System (SNIB-CONABIO). Information was crossreferenced with digital taxonomic systems such as the Catalog of Fishes of the California Academy of Sciences, the World Register of Marine Species (WoRMS), and the Integrated Taxonomic Information System (ITIS). There is a total of two subclasses two divisions, 13 orders, 44 families, 84 genera, and 217 species that represent approximately 18% of all living and described species of chondrichthyans worldwide. For the Mexican Pacific and the Gulf of California, 92 species of chondrichthyans are listed compared to 94 species for the Gulf of Mexico and the Caribbean Sea. Additionally, 31 species listed occur on both coasts of Mexico. The species richness of the Mexican chondrichthyans will surely continue to increase, due to the exploration of deep-water fishing areas in the EEZ. [ABSTRACT FROM AUTHOR]

Holt, R. E., Foggo, A., Neat, F. C., and Howell, K. L. 2013. Distribution patterns and sexual segregation in chimaeras: implications for conservation and management. – ICES Journal of Marine Science, 70: 1198–1205.Chimaeras such as Chimaera monstrosa and Hydrolagus mirabilis are commonly found in commercial bycatch of deep-sea fisheries in the Northeast Atlantic. Very little information exists on their life history, ecology or behaviour. Segregation of populations by sex and/or age classes has been demonstrated in several elasmobranchs, but whether segregation occurs in chimaeras, and if so what mechanisms are involved, remains unknown. This study investigates the distribution and sexual segregation of four species of chimaera (C. monstrosa, H. mirabilis, C. opalescens n. sp. and Harriotta raleighana) in relation to sex, size (maturity) class, bottom depth, and latitude. Data were obtained from annual trawl surveys undertaken by Marine Scotland, Aberdeen, from 1998–2009, at 400–2000 m in the Northeast Atlantic (55–59°N 5–11°W). A factorial General Linear Model (GLM) with planned contrasts indicated complex patterns of age- and sex-related segregation. All adult males and females were sexually segregated by depth: in all four species investigated females occurred at greater depths than males. Potential birthing grounds were identified for H. mirabilis. Latitudinal spatial segregation was not evident in relation to sex or maturity stage. The patterns of segregation reported here suggest a potential for differential exploitation of the sexes by spatially focused fisheries. [ABSTRACT FROM PUBLISHER]