title: Distribution, population biology, and trophic ecology of the deepwater demersal fish Halosauropsis macrochir (Pisces: Halosauridae) on the mid-Atlantic Ridge.
abstract: Halosauropsis macrochir ranked amongst the most abundant and widespread demersal fishes on the mid-Atlantic Ridge of the North Atlantic (Iceland-Azores) with greatest abundance at 1700-3500 m. All sizes, ranging from 10-76 cm total length, occurred in the area without any apparent spatial pattern or depth trend. Using otolith sections displaying growth increments assumed to represent annuli, the age range recorded was 2-36 years, but most individuals were <20 years. Length and weight at age data were used to fit growth models. No differences between sexes in length and weight at age were observed. The majority of samples had a surplus of males. Diet analysis showed that H. macrochir feeds on Crustacea, Teleostei, Polychaeta, and Cephalopoda, but few prey could be identified to lower taxonomical levels. The mid-Atlantic Ridge constitutes a major portion of the North Atlantic living space of the abyssal halosaur where it completes its full life cycle, primarily as an actively foraging euryophagous micronekton/epibenthos and infauna feeder, becoming a partial piscivore with increasing size.
authors.affiliation: Institute of Marine Research, Flødevigen, His, Norway. oddaksel@imr.no
authors.forename: Odd Aksel
authors.initials: OA
authors.lastname: Bergstad
authors.forename: Laura
authors.initials: L
authors.lastname: Clark
authors.forename: Hege Øverbø
authors.initials: HØ
authors.lastname: Hansen
authors.forename: Nicola
authors.initials: N
authors.lastname: Cousins
mesh_terms: D000821:Animal Feed; D053180:Animal Nutrition Sciences; D000818:Animals; D004463:Ecology; D005260:Female; D005399:Fishes / Q000502:physiology*; D005843:Geography; D008018:Life Cycle Stages; D008297:Male; D008954:Models, Biological; D009792:Oceans and Seas; D011157:Population Dynamics; D012737:Sex Factors; D013270:Stomach / Q000502:physiology