Seasonal distribution of orange roughy (Hoplostethus atlanticus) on the Porcupine Bank west of Ireland

Unexpected panmixia in a long‐lived, deep‐sea fish with well‐defined spawning habitat and relatively low fecundity

“…The orange roughy ( Hoplostethus atlanticus ) is a deepwater species found along continental slopes and seamounts between depths of 450 and 1800 m in the Atlantic, Indian and Pacific oceans (Branch 2001). In the northeast Atlantic, orange roughy have been found along the continental slope to the west of the British Isles (Shephard & Rogan 2006), north to the Faroe Islands (Thomsen 1998), off the south coast of Iceland (Magnusson & Magnusson 1995), and southwards along the Mid‐Atlantic Ridge to the Azores (Hareide & Garnes 2001). In the northwest Atlantic, orange roughy have been found to occur off Baffin Island southwards to the Corner Seamounts south of the Grand Banks (Kulka et al .…”

“…Fecundity is also very low relative to other teleost species of similar body size, with mean relative fecundity of 22 000–33 000 oocytes per kilogram (Pankhurst & Conroy 1987; Minto & Nolan 2006). Orange roughy are found year‐round on the ‘flat’ ground of the continental slopes, but mature fish migrate to form large spawning aggregations on seamounts or ‘hill’ features during the spawning season (Shephard & Rogan 2006). Eggs and larvae only spend approximately 10 days in the water column (Bulman & Koslow 1995; Zeldis et al .…”

Thermal, trophic and metabolic life histories of inaccessible fishes revealed from stable‐isotope analyses: a case study using orange roughy Hoplostethus atlanticus

“…atlanticus in the North Atlantic Ocean has proved difficult. Koslow () suggests that in the Southern Ocean, juvenile H. atlanticus are dispersed over the open sea floor prior to recruiting to seamounts, a conclusion supported by Shephard & Rogan () for the North Atlantic Ocean and consistent with the relatively deep location of juvenile H. atlanticus identified in this study. Recent trawl surveys of the Porcupine Bank conducted by the Marine Institute, Galway, recovered significant quantities of juvenile H. atlanticus between 50 and 250 mm L S in discrete locations at depths from 1000 to 1500 m, but rarely at depths much shallower than 1000 m, consistent with predictions here based on otolith chemistry (Marine Institute Galway, unpubl.…”

New records of orange roughy Hoplostethus atlanticus juveniles in Chile

“…Spatial and bathymetric distribution, duration, habitat and feeding of early life stages are poorly known (Shephard et al , 2007). Sexual maturity is reached at a wide range of sizes, between 24 and 37 cm fork length ( L F ), and ages between 21 and 40 years (Francis & Horn, 1997; Horn et al , 1998; Clark et al , 2000; Minto & Nolan, 2006; Shephard & Rogan, 2006). Therefore, for comparative purposes in the following discussion, fish <24 cm ( L F ) or younger than 21 years will be regarded as juveniles.…”

“…The evidence is, however, far from conclusive. Spawning migrations have been suggested by Francis & Clark (1998) and Shephard & Rogan (2006) between lower density areas where both immature and mature (spawning and non‐spawning) fish coexist to others dominated by dense spawning aggregations. Otolith microchemistry studies have suggested, however, limited dispersion of both juveniles and adults (Lester et al , 1988; Thresher & Proctor, 2007).…”