Crabeater seals and their mysterious attraction to the Hutt River (the sequel)

Crabeater seals and their mysterious attraction to the Hutt River (the sequel)

About three years ago, vertebrate curator Colin Miskelly made the ‘rash’ claim that the best bet for seeing a crabeater seal in New Zealand was to visit the mouth of the Hutt River in Wellington Harbour – and wait approximately 25 years.

But we didn’t have to wait that long, as one showed up there a few days ago. Colin gives his thoughts on why they come here. 

Hutt River mouth, looking across to Petone Beach. Photo by Colin Miskelly. Te Papa

Why 25 years?

The ‘rash claim’ was made in a Te Papa blog about vagrant Antarctic seals in New Zealand waters, which reported on eight known occurrences of crabeater seals, between 1885 and 2015.

Of these eight animals, a remarkable five of them were found up the Hutt River or on the adjacent Petone Beach. These animals turned up in 1916, 1933, 1934, 1963, and 2015.

While there was considerable spread in these occurrences (1 to 52 years apart), the average interval was just under 25 years.

Perforated pearlers – the bizarre teeth used by crabeater seals to sieve krill from Antarctic waters. Photo by Jean-Claude Stahl. Te Papa

Why the Hutt River?

I proposed two hypotheses as to why so many Antarctic seals turn up in Wellington, and the Hutt River in particular. The first was that unusual seals turning up near Wellington were more likely to be reported, and correctly identified, than those that turned up in more remote parts of the country. The second was that the orientation of the main islands of New Zealand would mean that any seal swimming north was likely to be guided up the east coast of the South Island and into Wellington Harbour, and then onto Petone Beach or up the Hutt River – provided that the animals were determined to keep swimming north.

Seal resting on land
The 2015 crabeater seal on the edge of the Hutt River. Image: Anneke Mace, Department of Conservation

I suggested that the first hypothesis could be tested over time, as the ubiquitous use of cellphone cameras means that it is more likely that vagrant seals anywhere in the country will be reported and correctly identified from these images. And this has proven to be the case. Since that last blog, five further rare vagrant Antarctic seals have reached the New Zealand coast – three crabeater seals and two Weddell seals. While there has been considerable spread in the sightings (from Southland to Hawke’s Bay), there is again a concentration in the southern North Island, including the latest animal videoed swimming strongly up the Hutt River, about 7 km from the mouth.

A crabeater seal swimming in the Hutt River, 20 July 2019. Video supplied by Kirsty Morrison

Additional records of wayward seals

The two additional Weddell seals were found alive at Awarua Bay, Southland, in April 2017, and at Kaikoura in July 2018, with the second animal also turning up at Napier the following month. The next two crabeater seals were an emaciated animal euthanised at Waikawa beach, Horowhenua, in July 2017, and one that crawled a kilometre inland from the head of Lyttelton Harbour (and subsequently died) in May 2019.

Like a moth to a flame

Crabeater seal at Karitane, Otago, 2 July 2019. Image: Gerard O’Brien, Otago Daily Times

The latest animal was first detected at Karitane, Otago, on 2 July. Recognisable by a distinctive pattern of injuries on its lower back, the same animal came ashore at Birdlings Flat, Canterbury, on 7 July. It then disappeared for a couple of weeks before resurfacing in the Hutt River on 20 July.

Crabeater seal at Birdlings Flat, Canterbury, 7 July 2019. Image: Sue Manson

Unfortunately, the animal was in poor condition when found on the edge of the river on 22 July, and it expired during an attempt to return it to the Wellington south coast.

Its movements since the first sighting support the suggestion that Wellington Harbour in general, and the Hutt River in particular, are natural traps for any southern fauna intent on heading north.

Now the average wait-time between sightings has been reduced to a more manageable 20.6 years!

Crabeater seal on the edge of the Hutt River, 22 July 2019. Photo by Colin Giddy, Department of Conservation

Further reading

The mysterious attraction of the Hutt River to crabeater seals

A crabeater seal – a long way from home

Miskelly, C.M. 2015. Records of three vagrant Antarctic seal species (Family Phocidae) from New Zealand: crabeater seal (Lobodon carcinophaga), Weddell seal (Leptonychotes weddellii) and Ross seal (Ommatophoca rossii). New Zealand Journal of Marine and Freshwater Research 49: 448-461.

5 Comments

  1. Avatar

    Really interesting and a little sad, thanks for keeping us informed.

  2. Avatar

    Liked this info..and pics..espec. the teeth!

    1. Colin Miskelly
      Author

      Kia ora Neil
      Yes – it is a great image. It is one of many superb Jean-Claude Stahl images included in the book ‘100 Natural History Treasures of Te Papa’ published by Te Papa Press a few months ago.
      Ngā mihi
      Colin

  3. Avatar

    So it is not just because the Hutt is a great place to catch crabs?

    Good blog e hoa, very interesting.

    1. Colin Miskelly
      Author

      Thanks very much for your feedback Jack
      Ngā mihi
      Colin

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