Food and feeding relationships of three sympatric slickhead species (Pisces: Alepocephalidae) from northeastern Chatham Rise, New Zealand

Abstract

The food and feeding relationships of mid-slope slickheads in New Zealand waters are little known compared with those from the northern hemisphere. This study examines the feeding relationships of three common slickhead species from approximately 1000m on Chatham Rise, New Zealand: Alepocephalus antipodianus (Parrot, 1948), A. australis (Barnard, 1923), and Xenodermichthys copei (Gill, 1884). The Alepocephalus species were predominantly benthopelagic feeders with a small benthic component to their diets. Alepocephalus australis fed on pelagic tunicates, notably Pyrosoma atlanticum Péron, 1804. Alepocephalus antipodianus fed on fish and pelagic tunicates, and also crustaceans. Xenodermichthys copei fed primarily on crustaceans. Considerable material was recovered from the intestines of all three species, and much of it was identifiable and only partially digested, including the remains of pelagic tunicates. There was little dietary overlap between the stomach contents of the three slickhead species indicating a degree of niche partitioning. Intestinal contents differed from stomach contents in weight, but not in number of items for all three species. The composition of stomach and intestinal contents differed for A. australis, but not for A. antipodianus or X. copei, which suggests that intestinal contents could be potentially useful in lieu of stomach content. There was a high level of overlap between the intestinal contents of A. antipodianus and A. australis, suggesting a possible closer dietary relationship between these two species than that indicated by stomach contents alone. Despite limitations in sample size and spatial and temporal coverage, the results from this study indicate that the three slickhead species could play an important role in the structuring of the demersal community at mid-slope depths on northeastern Chatham Rise.