Joint Meeting of Ichthyologists and Herpetologists, 2015

† Paul J. Clerkin1*, Jenny M. Kemper2, David A Ebert1

Investigation and taxonomy of Southwestern Indian Ocean Chimaeridae
1 – Moss Landing Marine Laboratories, 2 – College of Charleston, Oral Presentation, 2013 Joint Meeting of Ichthyologists and Herpetologists, American Elasmobranch Society, Reno, Nevada., July 2015.

Abstract

Historically understudied, the Chimaeriformes (Chondrichthyes: Holocephali) has received increased attention over the past decade and half, with the expansion of deep-sea fisheries, with 19 species having been described. Despite this recent focus, 59% of all known chimaeras are data deficient as accessed by the IUCN. This lack of information is due to taxonomic uncertainty and the intrinsic complexities associated with sampling at great depth in remote areas. The Southwestern Indian Ocean (SWIO) offshore ecosystem is a poorly explored, remote region characterized by extreme topology that includes the massive Madagascar Ridge. This region is punctuated by seamounts that function as isolated underwater islands, supporting high abundance of fish, and a number of chimaera species. Currently, very little is known about SWIO Chimaeras, since only two species have been verified from the area, Hydrolagus africanus, and Chimaera notafricana. During two surveys (2012 and 2014) onboard a commercial deep-sea trawler in the SWIO offshore, six distinct species of Chimaeridae (4 Chimaera, 2 Hydrolagus) were collected. A comprehensive set of morphometric and meristic measurements, and genetic samples were collected from each specimen encountered. Comparisons with geographic congers using standard morphological methods along with comparative genetic samples were made between SWIO offshore chimaeras and those from South Africa, Australia, and New Zealand to investigate similarities and differences between these geographical regions. Taxonomic resolution of this enigmatic Chondrichthyan group will lead to improved species-specific identification.

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