Featured Research

from universities, journals, and other organizations

Competition with humans responsible for decline of New Zealand's endangered sea lions, study shows

Date:
August 2, 2011
Source:
Wiley-Blackwell
Summary:
Marine researchers in New Zealand have identified the direct impact of fishing as the largest known human factor in the decline of the endangered native sea lion population. The team's findings discount non-human factors, such as disease and identifies resource competition and by-catch incidents as the most likely causes.

Marine researchers in New Zealand have identified the direct impact of fishing as the largest known human factor in the decline of the endangered native sea lion population. The team's findings, published in Mammal Review, discount non-human factors, such as disease and identifies resource competition and by-catch incidents as the most likely causes.

The New Zealand sea lion Phocarctos hookeri is the country's only native pinniped species and is listed as 'nationally critical'. The species breeds in the sub-Antarctic, south of New Zealand's mainland, with 71% of the population on the Auckland Islands and the remaining 29% on Campbell Island.

Breeding at the Auckland Islands has declined by 40% since 1998 with only 1501 pups being born in 2009. This decline is directly linked to females not returning to breeding areas. However, while the Auckland Island population has declined, the Campbell Island population appears to be slowly increasing.

Potential reasons for the decline in the Auckland Island population, but not in the Campbell Island colony, include non-human factors such as disease, predation, migration or environmental change. However, possible human factors include population 'overshoot', the effects of contaminants, resource competition and by-catch deaths.

Of the nine potential reasons for the decline of the sea lion population the team discounted six by comparing the Auckland island population with the colony on Campbell Island.

"The most plausible hypotheses based on available evidence is that the decline of breeding females in the Auckland Island population is caused by fisheries-induced resource competition and by-catch incidents" said author Dr Bruce Robertson, from the University of Otago. "Resource competition can lead to nutrient stress and decreased reproductive ability in sea lions and this should be a priority area for future research."

"A fundamental component of assessing and managing any species in decline is the long-term monitoring of changes in numbers and population dynamics in each population of the species," said Robertson. "Both human and natural influences must be taken into account and our study indicates the need for further research and greater conservation management to protect the species."


Story Source:

The above story is based on materials provided by Wiley-Blackwell. Note: Materials may be edited for content and length.


Journal Reference:

  1. Bruce C. Robertson, B. Louise Chilvers. The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes. Mammal Review, 2011; DOI: 10.1111/j.1365-2907.2011.00186.x

Cite This Page:

Wiley-Blackwell. "Competition with humans responsible for decline of New Zealand's endangered sea lions, study shows." ScienceDaily. ScienceDaily, 2 August 2011. <www.sciencedaily.com/releases/2011/08/110802085825.htm>.
Wiley-Blackwell. (2011, August 2). Competition with humans responsible for decline of New Zealand's endangered sea lions, study shows. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2011/08/110802085825.htm
Wiley-Blackwell. "Competition with humans responsible for decline of New Zealand's endangered sea lions, study shows." ScienceDaily. www.sciencedaily.com/releases/2011/08/110802085825.htm (accessed July 29, 2014).

Share This




More Plants & Animals News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
Jane Goodall Warns Great Apes Face Extinction

Jane Goodall Warns Great Apes Face Extinction

AFP (July 29, 2014) The world's great apes face extinction within decades, renowned chimpanzee expert Jane Goodall warned Tuesday in a call to arms to ensure man's closest relatives are not wiped out. Duration: 00:58 Video provided by AFP
Powered by NewsLook.com
How Your Face Can Leave A Good Or Bad First Impression

How Your Face Can Leave A Good Or Bad First Impression

Newsy (July 29, 2014) Researchers have found certain facial features can make us seem more attractive or trustworthy. Video provided by Newsy
Powered by NewsLook.com
Rat Infestation at Paris' Tuileries Garden

Rat Infestation at Paris' Tuileries Garden

AFP (July 29, 2014) An infestation of rats is causing concern among tourists at Paris' most famous park -- the Tuileries garden next to the Louvre Museum. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins