Diet and dietary variation of New Zealand hokiMacruronus novaezelandiae

Abstract

The diet of hoki was determined from examination of stomach contents of 1992 fish of 26Á112 cm total length (TL) sampled at depths of 209Á904 m on Chatham Rise, New Zealand, from summer research trawl surveys and seasonal commercial fishing trawls, during 2004Á2008. Prey was predominantly euphausiids, mesopelagic fishes and natant decapods. Multivariate analyses using distance-based linear models, non-parametric multi-dimensional scaling and similarity percentages indicated that the best predictors of diet variability were the position of the fish in relation to the subtropical front (STF), fish size and longitude. Pasiphaeids were more important to the north of the STF, and sternoptychid fishes and euphausiids more important in the STF convergence area. Euphausiids and sternoptychid fishes were important for smaller hoki (26Á55 cm TL), myctophid fishes and natant decapods for larger hoki, and macrourids for the largest hoki (!84 cm TL). The longitudinal effect was characterised by pasiphaeids, euphausiids and sternoptychids to the west, and myctophids in the centre of Chatham Rise. Feeding activity was analysed using generalised additive models, and was found to vary with time of day, sample source (research or commercial), longitude, hoki size and depth. The variability in diet suggested hoki forage opportunistically within their preferred habitat and biological limits.

Trophic Interactions and Distribution of Some Squaliforme Sharks, Including New Diet Descriptions for Deania calcea and Squalus acanthias

“…The subtropical front (STF) forms over Chatham Rise, where the mixing of subantarctic and subtropical water masses produces a region of heightened primary productivity [16], supporting abundant mesopelagic biomass [17]. Pronounced ecosystem changes across the STF on Chatham Rise have been correlated with changes in diet for several fish species [18]–[20], presumably because of variations in environmental conditions and prey availability.…”

Spatial variation in the diet of Patagonotothen tessellata (Pisces, Nototheniidae) from the fjords and channels of southern Chilean Patagonia

“…The effect of SL over the number of stomachs with prey indicated that larger fish had higher proportion of empty stomachs. The decrease in the number of stomachs with prey in relation to fish size has been documented in mesopelagic fish and may be associated with a less frequent consumption in larger fish linked to a decrease in metabolic rate compared with smaller fish (Post and Lee 1996;Connell et al 2010;Dunn and Forman 2011). Another factor that could have influenced the absence of prey in larger fish would be related to the reproductive activity of P. tessellata.…”

Diets of deepwater oreos (Oreosomatidae) and orange roughy Hoplostethus atlanticus

“…1000 m (Leathwick et al ., ). The range of habitats (Leathwick et al ., ), and influence of the STF, is expected to provide a variety of foraging opportunities for demersal fishes, which could lead to substantial variability in feeding ecology (Connell et al ., ; Dunn et al ., ; Horn et al ., ; Stevens & Dunn, ).…”

“…In this study, the diets of A. niger, P. maculatus, N. rhomboidalis and H. atlanticus were examined on Chatham Rise, New Zealand. This research was part of a wider study of trophic structure in the fish assemblage on Chatham Rise, and part of a substantial variability in feeding ecology (Connell et al, 2010;Dunn et al, 2010;Horn et al, 2010;. 2011 (all four species), January 2012 (all species except H. atlanticus) and January 2014 (N. rhomboidalis only).…”