Local Govt | National News Video | Parliament Headlines | Politics Headlines | Search

 


Boaties need to be mindful of dolphins

Friday, January 31, 2014

Boaties need to be mindful of dolphins


Click for big version.

Severe propeller strike wound on a bottlenose dolphin photographed at Great Barrier Island in September 2012. Photo Credit: Sarah Dwyer, Massey University.

Boaties heading out into the Hauraki Gulf over the summer need to take greater care in sharing the water, Massey researchers say, as they uncover the impact of collisions between vessels and marine mammals in the area.

In a new paper published this month in the New Zealand Journal of Marine and Freshwater Research, the impact of a boat propeller injury on a bottlenose dolphin was reported, with dismaying results.

Coastal-Marine Research Group (C-MRG) PhD student Sarah Dwyer was lead researcher for the recently published paper describing severe propeller strike injuries sustained by an immature bottlenose dolphin (Tursiops truncatus).

“In this instance, the bottlenose dolphin sustained injuries that penetrated to the bone. Considering the severity of the wounds, it was surprising that these injuries weren’t immediately fatal,” says Ms Dwyer.

The injured dolphin was identified as a calf when first sighted in May 2010, based on its size and associated swimming position with an adult bottlenose dolphin presumed to be its mother. The pair were always photographed together for the next two and a half years, until the mother was seen without her offspring a number of months after the injured dolphin was last sighted.

Post injury, the young bottlenose dolphin was observed with a very large open wound behind its dorsal fin and two more evenly spaced parallel wounds on the tail that were consistent with propeller strike injuries. Over the next 23 days, the wounds changed significantly, with increased soft tissue deterioration. The last reported sighting, in the shallow bays of Great Barrier Island, was on October 21, 2012.

It is highly unlikely the mother would have abandoned her injured offspring if it was still alive, therefore it is assumed that the injured dolphin did not survive even though a carcass was not recovered.

Bottlenose dolphins are particularly susceptible to human impacts because they are a coastal species, but Director of the Coastal-Marine Research Group Dr Karen Stockin says that the probability of vessels striking marine mammals decreases when speed is reduced.

“When the injured bottlenose dolphin was observed, it was towards the end of winter, when boat traffic is traditionally low. Risks to marine mammals increase as the number of vessels out on the water rises, so we need boaties to be acutely aware that they’re sharing the waters with other marine mammals, and, more importantly, to immediately report any incidents of vessel strike,” Dr Stockin says.

“Part of our research at the Coastal-Marine Research Group involves performing necropsies on dead mammals to ascertain the cause of death. Some die as the result of blunt force trauma where a vessel has hit a dolphin or a whale hard enough to kill it. We also observe dolphins and other marine mammals with wounds or scars from propeller strikes – some of which they can recover from, and others that later die from their injuries.”

The Hauraki Gulf is home to one of the busiest ports and shipping lanes in New Zealand, with a marked increase in traffic during weekends, with sail boats, personal watercraft (including jet-skis) and recreational fishing boats. It’s also shared with a wide range of marine mammals, including a number of different species of dolphins and whales using the waters to feed and nurse their young.

It’s difficult to work out how many marine mammals are killed or injured by vessel collision or propeller strike, mainly due to the lack of reporting when collisions occur as well as difficulties in recovering fatally-struck animals.

Marine mammals in New Zealand are legally protected under the Marine Mammal Protection Act (1978) — anyone who accidentally kills or injures a marine mammal is required to report the incident to a fishery officer or the Department of Conservation within 48 hours.

The Marine Mammal Protection Regulations (1992) covers commercial whale and dolphin watching activities, and incidental recreational interaction. Under these regulations vessels must avoid rapid changes in both speed and direction and not exceed speeds faster than the slowest mammal within a vicinity of 300 metres. Vessels travelling at speeds over 15 knots are more likely to kill a whale or dolphin if they hit it, and can still cause severe damage if travelling over five knots (or no wake speed).

The popular and highly manoeuvrable jet-ski has quieter underwater acoustics than normal boats. This makes them even harder for marine mammals to detect and avoid, as highlighted in a recent 2013 publication by Dr Stockin and C-MRG research associate Dr Emmanuelle Martinez, who reported the case of a common dolphin that died in the Hauraki Gulf as a result of blunt force trauma caused by a jet ski incident.

Recent C-MRG research aligns with previous studies that suggest most of the dolphins hit by vessels are either young calves or juveniles, or mothers with their young.

“There are several reasons why this occurs. Younger animals are slower swimmers, with limited diving capabilities. They spend more time at the surface and in shallower waters. They’re also naturally inquisitive and less cautious about vessels, so they lack awareness of danger until it’s too late,” says Dr Stockin. “We need people in all kinds of vessels – from commercial ships to motorboats, yachts, jet-skis and kayaks – to be considerate of other species sharing the waterways. The problem is far larger than just container ships hitting whales, yet most people seem oblivious to this.”

Sightings of dolphins can be reported to the Department of Conservation on 0800 DOC HOTline (0800 362 468) and there are also online forms on the website: http://www.doc.govt.nz/conservation/native-animals/marine-mammals/marine-mammal-sightings/marine-mammal-sighting-form/

Links to the published papers can be found here: www.cmrg.massey.ac.nz under the Publications tab.

ENDS

© Scoop Media

 
 
 
 
 
Parliament Headlines | Politics Headlines | Regional Headlines

'Tea Break Bill' Passes: Gordon Campbell On Bad Labour Laws And Poor Safety

By co-incidence, one of the prime dangers of the government’s new employment relations law has been underlined by the release of the death and injury statistics among workers at New Zealand ports. These are highly profitable enterprises for the port owners.

The Port of Tauranga for instance, is expecting its current full-year profit to be between $78 million and $83 million and other ports are enjoying similar boom times – but they are also highly dangerous places for the people who work on or around the port premises. At the Port of Tauranga, there have been 26 serious accidents since 2011, and two deaths. More>>

 

Parliament Today:

No Charges: Outcome Of Operation Clover Investigation

Police have completed a multi-agency investigation, Operation Clover, into the activities of a group calling themselves “The Roast Busters”. The 12 month enquiry focused on incidents involving allegations of sexual offending against a number of girls in the Waitemata Police district and wider Auckland area... More>>

ALSO:

UNICEF Report: NZ Cautioned On "Stagnating" Child Poverty

An international report by UNICEF has found that child poverty rates in New Zealand have barely changed since 2008, despite similar sized countries significantly reducing child poverty during the recent recession. More>>

ALSO:

Funding Report: Two Pathways For Transport In Auckland

Commissioned by Auckland Council, the group was asked to investigate two possible pathways for raising $300 million per year ($12 billion over 30 years) to pay for the improvements needed to help fix Auckland’s transport system. More>>

ALSO:

Pay Equity: Equal Pay Win In Court Of Appeal

CTU: The Court of Appeal has made a historic decision paving the way for a substantial equal pay claim for aged care workers. More>>

ALSO:

Gordon Campbell: On The TPP Finishing Line, And Amazon’s Woes

If the Trans Pacific Partnership trade deal wasn’t such a serious matter, this would be pretty funny… More>>

ALSO:

TV3 Video: Three Die On Roads Over Labour Weekend

The official holiday period ended at 6am Tuesday, with three deaths on the roads during the Labour Day weekend. More>>

Employment Relations Bill: Govt Strains To Get Tea Break Law Through

The Government has been left with egg on its face - failing to get its much-vaunted, but hugely unpopular, meal break law passed in the first week of its new term, Labour spokesperson on Labour Issues Andrew Little says. More>>

ALSO:

Guns: Police Association Call To Arm Police Full Time

"The new minister gave his view, that Police do not need to be armed, while standing on the forecourt of parliament. The dark irony was that the interview followed immediately after breaking news of a gunman running amok in the Canadian parliament in Ottawa..." More>>

ALSO:

Get More From Scoop

 

LATEST HEADLINES

 
 
 
 
 
 
 
 
Regional
Search Scoop  
 
 
Powered by Vodafone
NZ independent news