Snailfish

Abstract: Observations and records for fish exceeding 6000 m deep are few and often spurious. Recent developments in accessing and sampling the hadal zone 6000–11,000 m) have led to an acceleration in new findings in the deep subduction trenches, particularly in the Pacific Ocean. This study describes the discovery of two new species of snailfish (Liparidae) from the Mariana Trench; the ‘Mariana snailfish’ (6198–8076 m) and the ‘Ethereal snailfish’ (7939–8145 m). These new findings represent respectively the deepest known specimen caught with corroborating depth data, and the deepest fish seen alive. Further specimens and observations of the Kermadec Trench snailfish, Notoliparis kermadecensis , are also presented, as well as the first hadal records of Synaphobranchidae and Zoarcidae (6068 and 6145 m respectively) and a depth extension for the Macrouridae (maximum depth now 7012 m). Details of these new snailfish specimens caught by baited trap and behaviour observations filmed by baited cameras are presented. An updated assessment of fishes from hadal depths is also reported.

Abstract: This study represents the first demersal trawl survey of marine fishes and invertebrates in offshore waters of the Beaufort Sea since 1977. Species composition, distribution, and abundance of demersal fish and benthic invertebrates were assessed with standard methods and demersal trawl gear by the Alaska Fisheries Science Center. Fishes made up 6% of the total catch weight, and invertebrates made up the remaining 94% of the catch weight. A total of 32 species of fish were identified, two taxa were identified to genus and one to family, and 174 taxa of invertebrates were identified. The most abundant demersal fishes were polar cod (Boreogadus saida), eelpouts (Lycodes spp.), Bering flounder (Hippoglossoides robustus), and walleye pollock (Theragra chalcogramma). The most abundant invertebrates were notched brittle stars (Ophiura sarsi), snow crab (Chionoecetes opilio), mussels (Musculus spp.), and the mudstar (Ctenodiscus crispatus). We documented or confirmed extension to the known ranges of four species of fishes: walleye pollock, Pacific cod (Gadus macrocephalus), festive snailfish (Liparis marmoratus), and eyeshade sculpin (Nautichthys pribilovius). We also documented the presence of commercial-sized snow crab (Chionoecetes opilio), which has not previously been recorded in the North American Arctic.

Abstract: Pseudoliparis swirei sp. nov. is described from 37 individuals collected in the Mariana Trench at depths 6898–7966 m. The collection of this new species is the deepest benthic capture of a vertebrate with corroborated depth data. Here, we describe P. swirei sp. nov. and discuss aspects of its morphology, biology, distribution, and phylogenetic relationships to other hadal liparids based on analysis of three mitochondrial genes. Pseudoliparis swirei sp. nov. is almost certainly endemic to the Mariana Trench, as other hadal liparids appear isolated to a single trench/ trench system in the Kermadec, Macquarie, South Sandwich, South Orkney, Peru-Chile, Kurile-Kamchatka and Japan trenches. The discovery of another hadal liparid species, apparently abundant at depths where other fish species are few and only found in low numbers, provides further evidence for the dominance of this family among the hadal fish fauna.

Abstract: The mesopelagic community of fishes and squids are fundamental in the diet of apex predators, but in most cases their life histories and habitat requirements are poorly understood. In May 1999, a pilot study was conducted to identify mesopelagic nekton, describe dominant physical characteristics of their habitat, and compare their relative abundances over several study sites in the southeastern Bering Sea. Biological samples were collected at 250, 500, and 1000 m depths with an open pelagic rope trawl lined with 1.2-cm mesh in the codend. Net type, mesh size, and trawling techniques were designed to parallel those of extensive Russian research surveys in the western Bering Sea, permitting direct comparisons between study results. Forty-three species of fish and 15 species of cephalopods were identified, including a new species of gonatid squid and a range extension for Paraliparis paucidens, a snailfish never before observed in Alaskan waters. Faunal biomass was high with over 25,000 (1400 kg) fish and squid collected in only 13 trawls. Concentrations of fish in this area surpass published records from the western Bering Sea and North Pacific Ocean by an order of magnitude, driven primarily by Leuroglossus schmidti, a deep-sea smelt. Generally, specimens were of high quality, and new size records were established for several species of fish and squid. The physical environment as determined from altimetry, satellite-tracked drifters, and water properties (temperature and salinity) was typical of the last decade for this area. Spatial patterns in species distribution were observed, but further research is needed to determine whether these are a factor of mesoscale variability or of habitat characteristics.