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Lineage – Scientific methodology

Annual distribution of the ‘giant’ lineage

The ‘giant’ or whip-lash squid Idioteuthis (previously ) cordiformis (Chun, 1908) (Family Mastigoteuthididae) is a widespread deepwater species reported from the western and central South Pacific Ocean, the Tasman Sea, and off northwestern Australia (Lu & Phillips 1985, Lu & Boucher-Rodoni 2001). It appears to be widely but irregularly distributed in the seas around New Zealand.

1. Literature

Using the keywords Idioteuthis cordiformis, extracts were made from Google, Aquatic Sciences and Fisheries Abstracts, Web of Science, and NIWAcat (all records at 22 November 2005). Relevant publications were obtained and used to help define distribution. Outside New Zealand waters, the species seems to have been reported mainly from depths around 800 m (e.g., Chun 1908). O’Shea (1997) illustrated a specimen taken at 900 m off East Cape. O’Shea (1999) illustrated a further specimen, this one from the northern Challenger Plateau, and reported specimens from the Lord Howe Rise and on the Bay of Plenty seamounts. It appears that this species has become locally extinct in areas where it once had been common—particularly along the Chatham Rise and off the east coast of the North Island south of East Cape.

2. Museum holdings

NIWA’s AllSeaBio database was examined for records on 26 August 2005, with no specimens recorded. Additions made to the collection since about 1995 have not been loaded onto this database; a search on 30 November 2005 for identified and shelved Idioteuthis cordiformis revealed no samples. There are three formally identified specimens of I. cordiformis in the National Museum of New Zealand Te Papa Tongarewa collection (Bruce Marshall, Collection Manager Molluscs, pers. comm.), all having come from north of the Chatham Rise. No other museum holdings were considered because discussions with Dr O’Shea, Auckland University of Technology, Auckland, indicated that any material held would not have been formally identified.

3. Ministry of Fisheries databases

The trawl and obs databases were examined for information on the distribution of this squid (species code ICQ) on 30 November 2005, with a single report from the Campbell Rise at 600 m. However, this is most unlikely to have been I. cordiformis this far south (Steve O’Shea, pers. comm.).

4. Summary

The 100% distribution takes in all parts of the New Zealand region, within the depth range 500–1000 m, north of the Subtropical Convergence on the east coast and on and north of the Challenger Plateau on the west coast. This squid is associated with areas of hard bottom, on both seamounts and elsewhere, but it is not possible on the distribution map— to be viewed at the national scale—to distinguish areas of hard bottom from soft. Whereas hotspots of occurrence might in earlier times have included the Chatham Rise and the east coast of the North Island south of East Cape, these areas are now considered to be no more than part of the 100% layer; trawling may have contributed to this apparent reduction in stock size. The Known not to exist layer comprises all regions south of the 100% distribution, and all depths throughout <500 m and >1000 m. However, so little detailed information is available for this squid that this understanding of its distribution is very tentative and it may change radically as more material becomes available and as the ecological requirements of the species become better known.

This information on the distribution of I. cordiformis was synthesised by John D. Booth NIWA, Wellington and reviewed by Steve O’Shea (Auckland University of Technology). The rounded 100% and Known not to exist distributions were digitised and imported into a GIS software package as layers. The area of each distribution class was calculated and the layers linked to attribute and metadata files.

No additional records of the species outside of the known range were identified in reviews carried out in November 2007 and May 2009.

5. References

Chun, Von C. (1908). Uber Cephalopoden de Deutschen Tiefsee- Expedition. Zoologischer Anzeiger 33: 86–89.

Lu, C.C.; Phillips, J. (1985). An annotated checklist of the Cephalapoda from Australia waters. Occasional Papers from the Museum of Victoria 18: 277–310.

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Lu, C.C.; Boucher-Rodoni, R. (2001). from the waters around Wallis and Fortuna Islands in the central South Pacific. Memoires du Museum National d’Histoire Naturelle 185: 369–399.

O’Shea, S. (1997). Giant squid in New Zealand waters. Seafood New Zealand November: 32–34.

O’Shea, S. (1999). Bycatch—the common, unique, and bizarre. Seafood New Zealand June: 45–51.

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