Hyperoglyphe

Abstract: The diet of the bluenose or deepsea trevalla Hyperoglyphe porosa (Richardson) was determined from the stomach contents of 78 trevalla caught at five localities over the continental slope off south‐eastern Australia (37–39° S, 142–151° E). The pelagic tunicate Pyrosoma atlanticum Peron was the most common organism present, although squids, pelagic and benthic fishes, and crustaceans were found in the stomachs of some trevalla. Trevalla are probably benthopelagic and feed mainly above the bottom during the day; at night they stop feeding and move to the bottom.

Abstract: Epipelagic juvenile bluenose, Hyperoglyphe antarctica (Carmichael 1818), are recorded from New Zealand for the first time. Two specimens were collected beneath flotsam nearNga Motu/Sugar Loaf Islands, west coast North Island in September 1996, and at least 20 were found inside a piece of trawl net drifting east of Cape Kidnappers, east coast North Island in September 1997. Live specimens between 65 and 87.3 mm standard length were cryptically coloured and were able to change their body colour from dark coppery‐bronze to blue. Freshly dead specimens lacked the thick mucous coat found in juveniles of other Hyperoglyphe species known to associate with jellyfish. We suggest that H. antarctica recruitment may be higher along the lower east coast North Island because of retention of flotsam‐associated juveniles in the East Cape and Wairarapa Eddies, and that juveniles spawned off south‐east Australia may reach New Zealand in the Tasman Current.

Abstract: Diet of bluenose warehou, Hyperoglyphe antarctica, was investigated from samples collected during commercial fishing (trawling and longlining) on seamounts in the Tristan da Cunha EEZ in the South Atlantic Ocean. Bluenose warehou (57–123 cm TL, N = 309) was found to forage on a broad range of prey, dominated by mesopelagic cephalopods (squid families Onychoteuthidae and Histioteuthidae, Pholidoteuthis massyae and octopus Haliphron atlanticus), Thaliacea (salps and pyrosomes) and a sternoptychid Maurolicus inventionis. Bluenose warehou exhibited a range of foraging strategies from browsing on dense aggregations of passively drifting jelly-like zooplankton to catching mobile nektonic fish. Bluenose also consumed body parts of the gelatinous giant octopus H. atlanticus, which may have been scavenged or predated. The study indicates that bluenose warehou has an unusually broad prey range for a teleost. The diversity of prey and high flexibility of the hunting strategies permitted the bluenose warehou to prosper in the highly changeable and dynamic environments of underwater seamounts.