Conservation Comment: Sightings mean time to act

The reappearance of tohora and discovery of blue whales locally means iron sand mining must be prevented, Margie Beautrais says. Photo / File

THERE was great excitement at the North Mole in Whanganui last week after the unusual and unexpected appearance of a massive whale and her calf close to shore.

Spectators watched for about an hour until the pair slowly began making their way westwards along the coast. Judging by the adult's size, lack of dorsal fin and the presence of callosities (large, white, rough growths) on the skin around the adult's head, it was suggested they were Southern right whales.

Tohora, or Southern right whales (Eubalaena australis), are a New Zealand native migrant species. They live mostly in sub-Antarctic waters around the Auckland and Campbell islands and breed during winter and spring. Tohora are the only large baleen whales seen from our beaches, and there are occasional sightings around mainland New Zealand.

A few months ago, Wellington residents were entertained for several weeks by a tohora frolicking in the harbour. In August another two mothers and their calves were seen offshore, one at Petone and one off the Kāpiti Coast. This was the first recorded sighting of a tohora mother and calf in Wellington Harbour in modern times.

A century ago, tohora were hunted almost to extinction because they were the "right whale" to catch. Before that, they were common enough for the South Taranaki Bight to be called "Mothering Bay" because of the large numbers of mother whales and their calves that gathered here.

Recent marine studies have revealed there is also a resident population of pygmy blue whales in the South Taranaki Bight. They feed on an up-welling ocean current that produces massive amounts of krill, the tiny crustaceans that blue whales eat.

By using biopsy darts to collect DNA samples and recording whale-songs, researcher Leith Torres, from Oregon State University, was able to identify 151 individual blue whales in the area. Her study demonstrated this is a genetically distinct population, estimated at 718 whales, and could possibly be a new sub-species of pygmy blue whales.

Margie Beautrais

With the reappearance of tohora off the Whanganui coastline and the significant discovery of a resident blue whale population in our area, it is even more imperative public pressure is applied to prevent Trans-Tasman Resources Ltd from mining the seabed of the South Taranaki Bight for iron sand.

The company's website claims its operation to remove 50 million tons of sand per year will create 1600 jobs and increase New Zealand's GDP by $150 million per year. The company states this will translate to more than 290 jobs in Whanganui and South Taranaki, and increase GDP locally by $150m per year.

There is no detail provided to support these claims. While the High Court has recently overturned the Environmental Protection Authority's decision to allow mining to proceed, the company is launching an appeal to the High Court. So it's not time to celebrate yet.

If we want the South Taranaki Bight to be a healthy marine habitat for such stupendous and amazing creatures as Southern right whales and pygmy blue whales, we need to continue applying public pressure and defending the right of these incredible creatures to remain living undisturbed in their own patch of ocean.

Margie Beautrais is educator and team leader of education and life-long learning at the Whanganui Regional Museum