Size matters: Large Marine Protected Areas work for dolphins

March 27, 2012
This is a female Hector's dolphin jumping off Banks Peninsula, New Zealand, inside the Banks Peninsula Marine Mammal Sanctuary. Credit: Copyright Steve Dawson

Ecologists in New Zealand have shown for the first time that Marine Protected Areas – long advocated as a way of protecting threatened marine mammals – actually work. Their study, based on 21 years' monitoring and published today in the British Ecological Society's Journal of Applied Ecology, reveals that a marine sanctuary off the coast of Christchurch has significantly improved survival of Hector's dolphins – one of the rarest dolphins in the world.

Covering 1170 km2 of sea off New Zealand's South Island, Banks Peninsula Sanctuary was designated in 1988 to prevent the being killed by gillnet and trawl fisheries.

Over 21 years between 1986 and 2006, researchers conducted regular photo-identification surveys of Hector's dolphins, photographically capturing 462 reliably-marked individuals, whose survival they studied.

According to one of the team, Dr Liz Slooten of the University of Otago: "We can identify individual dolphins from their battle scars – which range from small nicks out of the dorsal fin to major scarring following shark attacks."

The team analysed the photographic re-sightings using a so-called Bayesian mark-recapture technique and then used a population model to assess the impact of the Marine Protected Area (MPA) on Hector's dolphins.

The results showed that since the MPA was designated, the dolphin's survival has increased by 5.4%. According to Dr Slooten: "This study provides the first empirical evidence that Marine are effective in protecting threatened marine mammals."

But she warns that while survival has improved significantly, it is not yet high enough to prevent the population from continuing to decline.

MPAs, in which certain fishing methods are banned or restricted, are often used to help conserve marine mammals. Until now, there has been little if any empirical evidence of their effectiveness, so measuring their impact is crucial to justify setting up MPAs.

As well as providing the first hard evidence that MPAs work, the study illustrates the importance of long-term ecological monitoring, as Dr Slooten explains: "Estimating population changes in marine mammals is challenging, often requiring many years of research to produce data accurate enough to detect these kinds of biological changes."

The study also shows that to be effective, MPAs need to be sufficiently large. "The take home message is that size matters. work, but they have to be large enough in order to be effective," she concludes.

Explore further: Bacteria responsible for the death of Maui’s dolphins

More information: Andrew M Gormley, Elisabeth Slooten, Steve Dawson, Richard J Barker, Will Rayment, Sam du Fresne and Stefan Brager (2012). 'First evidence that Marine Protected Areas can work for marine mammals', doi: 10.1111/j.1365-2664.2012.02121.x , is published in the Journal of Applied Ecology on Tuesday 27 March 2012.

Related Stories

Dolphin population at risk in Britain

May 16, 2007

A report from the Wildlife Trusts and an animal charity has found that commercial fishing in Britain is placing the regional dolphin population at risk.

Marine protected areas conserve Mediterranean red coral

May 11, 2010

A team of Spanish and French researchers has undertaken a pioneer analysis of red coral populations in the oldest Marine Protected Areas (MPA) in the Mediterranean and the impact that fishing activity has had. Results show ...

Marine Protected Areas are keeping turtles safe

March 18, 2012

Marine Protected Areas (MPAs) are providing sea turtles with an ideal habitat for foraging and may be keeping them safe from the threats of fishing. A study by an international team of scientists led by the University of ...

Recommended for you

Researchers design first artificial ribosome

July 29, 2015

Researchers at the University of Illinois at Chicago and Northwestern University have engineered a tethered ribosome that works nearly as well as the authentic cellular component, or organelle, that produces all the proteins ...

Studies reveal details of error correction in cell division

July 29, 2015

Cell biologists led by Thomas Maresca at the University of Massachusetts Amherst, with collaborators elsewhere, report an advance in understanding the workings of an error correction mechanism that helps cells detect and ...

Researchers discover new type of mycovirus

July 29, 2015

Researchers, led by Dr Robert Coutts, Leverhulme Research Fellow from the School of Life and Medical Sciences at the University of Hertfordshire, and Dr Ioly Kotta-Loizou, Research Associate at Imperial College, have discovered ...

Stressed out plants send animal-like signals

July 29, 2015

University of Adelaide research has shown for the first time that, despite not having a nervous system, plants use signals normally associated with animals when they encounter stress.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.