Lineage Annual Distribution of the Paddle Crab 1. Literature Sources

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Lineage

Annual Distribution of the Paddle Crab

1. Literature sources

The literature was searched for distributional information for adults of the paddle crab, Ovalipes catharus (White, 1843). This crab is locally common on open sandy beaches and in harbours and the mouths of estuaries throughout mainland New Zealand, Stewart Island, and the Chatham Islands, from the intertidal to more than 10 m (McClay 1988, Stevens 1999, O’Driscoll et al 2003). It is also found in east and south Australia. Size at maturity varies geographically, those from Tasman Bay maturing smaller (50 mm carapace width - CW) than those in Pegasus Bay (65 mm CW) (Osborne 1987, Armstrong 1988, Stevens 1999). In this layer 55 mm CW is taken to be the minimum adult size.

a. Using the keywords paddle crab* or ovalipes catharus or o catharus, extracts were made from Aquatic Sciences and Fisheries Abstracts (all records at 27 July 2003) and NIWAcat (all records at 27 July 2003). Using the keywords paddle crab new zealand (pages from New Zealand), extracts were made from Google (all records, 2 October 2003). Relevant publications were obtained but none was useful in extending the distribution of the species beyond that described above. b. Using subject indices for 1986–2002, Seafood New Zealand was checked for articles dealing with paddle crab distribution and research. None was useful in extending the distribution of the species beyond that described above. c. New Zealand Fishing News, 1998–2002 inclusive, was checked for articles dealing with paddle crabs to help estimate presence/absence. None was useful in extending the distribution of the species beyond that described above. d. Using the keywords (anywhere or global) crab and thesis or ovalipes and thesis (The University of Auckland, Auckland University of Technology, The University of Waikato, Massey University, Victoria University of Wellington, University of Canterbury, University of Otago), library catalogues were checked between 7 July and 12 August 2003, and relevant theses obtained and examined. None was useful in extending the distribution of the species beyond that described above, but some provided more detailed local distribution and abundance information.

2. Ministry for Primary Industries electronic databases

a. Estimated mean annual CELR database catches for the period 1 October 1989 to 30 June 2003 (extracted in mid 2003) were plotted by statistical area. All significant (> 1 t) reported landings were made from the northeast of the North Island (Statistical areas 002, 003, 008, 009, and 013), the southeast of the North Island (013 and 014), the southwest of the North Island (039), Tasman and Golden Bays (038), and Pegasus Bay (020). The statistical areas of some ostensibly offshore catches were not considered to have been accurately reported (eg., 001, 021, and 609). b. The main fishing areas for paddle crabs are the east coast of New Zealand (PAD 1, PAD 2 and PAD 3), the northwest of the South Island (PAD 7), and the southwest of the North Island (PAD 8) (Stevens 1999, Anon 2003). Paddle crabs reported from the subantarctic islands (PAD 6; up to 50 t per year) are probably Nectocarcinus spp. c. Research bottom trawl records: trawl database. All records of this crab at least 55 mm CW being taken, 10 February 1979 to 11 September 2003, were extracted on 11 September 2003 and the positions of the stations plotted in 0.25 degree rectangles. The data were used to estimate presence and absence. They did not extend the distribution of the species beyond that described above, all having been reported from inshore waters of the Bay of Plenty. d. Scientific observer records from larger vessels: obs and obs_lfs databases. All records of this crab at least 55 mm CW being taken to 11 September 2003 were extracted on 11 September 2003 and the positions of the stations plotted in 0.25 degree rectangles. The data were used to estimate presence and absence. Many reports of this crab, in waters on the edge of the Snares Shelf, around the Auckland Islands, and on the Chatham Rise are thought to be misidentified Nectocarcinus spp. e. The recreational fishing database rec_data was examined on 18 August 2003. The recRamp database contained no records for this crab. The recDiary database contained just under 50 records, most from Bay of Plenty, eastern Northland, but others as far south as Otago. Presumably the low number of records was why Bradford (1998) did not include O. catharus in her analysis of the 1996 National Marine Recreational Fishing Survey. Provisional results from the 1999-2000 National Marine Recreational Fishing Survey showed highest estimated harvests (in numbers) of paddle crab to be in PAD 1 (east coast North Island north of Cape Runaway) and PAD 8, the next most important areas being PAD 9 (northern half of the west coast of the North Island) and PAD 2 (east coast North Island south of Cape Runaway). In summary, recent recreational catches of paddle crabs have been highest in the northeast and southwest of the North Island.

No other Ministry for Primary Industries databases were checked because none was thought to contain any useful information on the distribution of paddle crabs.

3. Museum holdings

Holdings of O. catharus in the following museums were examined. Other museum holdings were not investigated because it was considered that they would not add anything to the record. Data were used to help estimate presence/absence.

a. NIWA Greta Point. The AllSeaBio database was examined for records on 23 July 2003, with no O. catharus being taken from beyond North, South, or Chatham Islands. Additions made to the collection since about 1995 have not been loaded onto this database; in a search on 19 October 2003, none of the O. catharus identified and shelved were taken from beyond the North, South, Stewart, or Chatham Islands. b. Museum of New Zealand Te Papa Tongarewa (Te Kahui) records of this species based on voucher specimens held in their collection were examined, all having been collected around the North, South, or Chatham Islands. One specimen came from about 90 m depth east of the Chathams.

4. Summary.

Adult paddle crabs O. catharus live around the North, South, Stewart, and Chatham Islands, mainly on both sheltered and exposed sandy beaches and in harbours and the mouths of estuaries. They are also found in east and south Australia. Fishery records of this species from south of Stewart Island are thought to be misidentified Nectocarcinus spp. They are most often found at depths of less than 10 m, but can be found anywhere in the water column in much deeper offshore waters, to 100 m or more (Osborne 1987a, b). For example they were abundant in dredge samples to at least 60 m at the Chathams (Bull 1990). Abundance seems to have increased significantly since the 1970s, possibly the result of a decline in abundance of predators.

Tagging and other studies have shown that paddle crabs are migratory, these movements being related to breeding, moulting, and feeding. Males and females aggregate and mate in sheltered inshore waters during winter, and it is thought that the females then migrate offshore to deeper waters, generally during September to March (Osborne 1987a, b). This migration is not well enough known to be depicted as separate seasonal distributions: it appears to be largely confined to females and there is no evidence that their migration takes them along the coast rather than simply to deeper waters.

Most of the information on the distribution and abundance of O. catharus is general in nature. It is found from the far north off Cape Reinga to the harbours and beaches of southern Stewart Island and the Chatham Islands. It is not known from the Three Kings Islands, Kermadec Islands,

or any of the subantarctic islands. The commercial CELR and the recreational databases were accorded most weight when estimating relative abundance around the coast. This crab is most abundant in northern and central parts of New Zealand. Hotspots of occurrence are the east coast of Northland, Bay of Plenty, Poverty and Hawkes Bays, the Wellington west coast beaches, Tasman and Golden Bays, and Pegasus Bay.

The above information on the distribution of O. catharus, derived mostly from accounts in the literature, museum collections, and fishery records, was reviewed by Mr Rick Webber, Collection Manager Marine Invertebrates, Museum of New Zealand Te Papa Tongarewa and then integrated by hand onto a large-scale map of New Zealand. The rounded lines were then digitised and imported into a GIS software package as layers. The areas of each distribution class were calculated and the layers were linked to attribute and metadata files. The map, because of its scale, cannot be taken to accurately define the local distribution of this species.

5. References.

The following publications were the key references and/or the ones most useful in describing the recent/current annual distribution of the paddle crab, O. catharus. The list is not intended to be an exhaustive bibliography of publications about this species.

Anon (2003). Paddle crabs (PAD) (Ovalipes catharus) http://www.environment.govt.nz/indicators/marine/fish/catch/pad/ Armstrong, J.H. (1988). Reproduction in the paddle crab Ovalipes catharus (Decapoda: Portunidae) from Blueskin Bay, Otago, New Zealand. New Zealand Journal of Marine and Freshwater Research 22: 529–536. Bradford, E. (1998). Harvest estimates from the 1996 national marine recreational surveys. New Zealand Fisheries Assessment Research Document 98/16. Bull, M.F. (1990). Report on a survey of the scallop resource at the Chatham Islands, 22 April – 5 May 1990. Central Fisheries Region Internal Report 16. McClay, C.L. (1988). Brachyura and crab-like Anomura of New Zealand. Leigh Laboratory Bulletin No. 22. O’Driscoll, R.L.; Booth, J.D.; Bagley, N.W.; Anderson, O.F.; Griggs, L.H.; Stevenson, M.L.; Francis, M.P. (2003). Areas of importance for spawning, pupping or egg-laying, and juveniles of New Zealand deepwater fish, pelagic fish, and invertebrates. NIWA Technical Report 119. Osborne, T.A. (1987a). Seasonal distributions and movements of the paddle crab Ovalipes catharus in Canterbury coastal waters. Maui Ora 14: 43– 55.

Osborne, T.A. (1987b). Life history and population biology of the paddle crab, Ovalipes catharus. Unpublished PhD thesis, University of Canterbury. Stevens, D.W. (1999). A summary of biology and commercial landings and a stock assessment of paddle crabs, Ovalipes catharus (White, 1843) (Crustacea, Portunidae), in New Zealand. New Zealand Fisheries Assessment Research Document 99/18.

2007 Update.

A Google search (Ovalipes catharus) on 7 September 2007, and searches of Seafood New Zealand (September 2005 to August 2007) and New Zealand Fishing News for 2006, did not yield any information that extended or altered the above distributions.

An examination on 17 September 2007 of the specify database of the NIWA National Invertebrate Collection for any new (post-July 2005) collections and any new (post-July 2005) identifications of old material did not lead to any extension or change to the distribution map. Similarly, there have been no further, formally identified shelvings of material in the Te Papa collections that extended or altered the distribution (Rick Webber, Collection Manager Marine Invertebrates, Museum of New Zealand Te Papa Tongarewa, pers. comm.).

The above was discussed with Rick Webber on 24 September 2007 and it was agreed that the current distribution map remains the best understanding of the distribution of this species. However, because of its scale, this map cannot be taken to accurately define the local distribution of this species. It remains unknown if this crab lives on Mernoo Bank.

2010 Update.

A Google search (Ovalipes catharus) on 6 September 2010, and searches of Seafood New Zealand (September 2007 to September 2010) and New Zealand Fishing News (October 2009 to October 2010), did not yield any information that extended or altered the above distributions.

An examination on 12 September 2010 of the specify database of the NIWA National Invertebrate Collection for any new (post-August 2007) collections and any new (post-August 2007) identifications of old material, as well as catch effort data from the Ministry for Primary Industries (1 August 2007 to 19 October 2010, Rep Log 7940) did not lead to any extension or change to the distribution map.

The above was discussed with Rick Webber on 29 October 2010 and it was agreed that the current distribution map remains the best understanding of the distribution of this species. However, because of its scale, this map cannot be taken to accurately define the local distribution of this species. It remains unknown if this crab lives on Mernoo Bank.

2012 Update.

A Google search (Ovalipes catharus) on 9 August 2012, and searches of Seafood New Zealand (September 2007 to September 2010) and New Zealand Fishing News (October 2009 to October 2010), did not yield any information that extended or altered the above distributions.

An examination on 3 August 2012 of the specify database of the NIWA National Invertebrate Collection for any new (post-June 2010) collections and any new (post-June 2010) identifications of old material did not lead to any extension or change to the distribution map.

The above was discussed with Rick Webber on 21 August 2012 and it was agreed that the current distribution map remains the best understanding of the distribution of this species. However, because of its scale, this map cannot be taken to accurately define the local distribution of this species. It remains unknown if this crab lives on Mernoo Bank.