An international research team led by University of Otago scientists has shown that New Zealand’s Chatham Islands were once home to a unique population of sea lion, that was driven to extinction soon after first human settlement.
The researchers used ancient-DNA analysis, radiocarbon dating and computational modelling to reveal the relationships of the unique prehistoric population, and also to understand the reasons for its sudden extinction a few hundred years ago.
Dr Nic Rawlence, who carried out the genetic study, says the team found a previously undiscovered lineage of sea lion on the isolated Chatham Islands, 650 km east of mainland New Zealand. The unique prehistoric Chathams sea lion was genetically clearly distinct from the modern population that persists in the Auckland and Campbell Islands, and mainland New Zealand today.
“The Chathams supported a large, genetically diverse population of this unique sea lion, which went rapidly extinct around 1650 AD, following Polynesian settlement of the islands only 200 years earlier” says Dr Rawlence.
“The regional New Zealand sea lion population now contains only a fraction of the genetic diversity it once had”, says Dr Catherine Collins, who was also involved in the study.
The Otago team used computational modelling to determine the level of human hunting likely to have caused the Chathams sea lion extinction.
“Modelling indicated that hunting rates greater than one sea lion/person/year resulted in the extinction of native populations with 200 years of first human settlement”, says Dr Justin Maxwell, an Otago archaeologist involved with the study.
“Sea lions were not able to withstand even low levels of sustained hunting pressure”, says Dr Maxwell.
The findings may also have important implications for the continued survival of New Zealand’s modern sea lions, says project leader Professor Jon Waters. “We used the same modelling approach to estimate the survival prospects for the modern population under different mortality rates”.
Sea lions are listed as endangered by the IUCN Red List. With only around 10,000 individuals remaining, the population is in serious decline (50% decline in pup births since 1998), with fisheries bycatch and resource competition the likely culprits.
“The team’s computer models suggest that current reported and unreported bycatch levels may be unsustainable for the long–term survival of the species. Our study adds to the growing evidence that undetected sea lion bycatch may still be driving the decline of the species, something the government’s recently released sea lion threat management plan (TMP) dismisses.” says Assoc. Prof Bruce Roberston, an Otago sea lion biologist, who was involved in the study.
“Overall, this study is a great example of how ancient-DNA can be used to inform conservation strategies of currently endangered species”, says Dr Rawlence.
“What our research shows is that human harvesting and sea lions do not mix. Unless measures are taken to mitigate continuing bycatch levels, the outlook for our sea lions is bleak”.
This Marsden and Allan Wilson Centre funded research included team members from the Universities of Otago, California, and Southern Methodist University, as well as the Museum of New Zealand Te Papa Tongarewa and Canterbury Museum.
The research has been published this week in the international journal Molecular Ecology (http://onlinelibrary.wiley.
The NZ Sea Lion Threat Management Plan is now open for submission for 6 weeks until 5th August 2016
The New Zealand sea lion is now listed in NZ as `nationally critical’ and internationally by IUCN `engandered’, (it was previously only as `vulnerable’) This has prompted the development of the TMP.
“A Threat Management Plan (TMP) for New Zealand sea lions has now been developed by the Department of Conservation and Ministry for Primary Industries, and reviews all natural and human-induced threats to sea lions and explores protection measures to ensure their survival.
The TMP will provide a 5 year programme aimed at reducing the decline, with a long-term goal of reversing the decline of sea lions so that they return to a thriving population.”
Find out how to have your say here: The NZ Sea Lion Threat Management Plan
The final numbers are (mostly) in, and the news is (mostly) good for the 2015/2016 NZ Sea Lion mainland breeding season!
Since our last update, one of our Trustees happened across six-year old Pippa with a healthy male pup in tow, bringing our pup total in Otago up to would-be double digits (10) for the first time since sea lions returned to the mainland. “Would-be” because, sadly, just the previous day Nature Guides Otago owner Hildegard Lubke discovered Mia’s pup dead from a large stomach wound on Allans Beach. Autopsy concluded it was killed by a shark. One of its first swims, just in the wrong place at the wrong time
All the pups are now at the age where they begin learning how to swim, and their mums may start shifting them to other locations. While this can make the pups vulnerable to predators in the water, it also means their mums can be responsive to land-based threats or disturbances (natural or otherwise) and relocate them to safer spots.
This week we were pleased to witness Patti and her female pup moving from their very public location to a more secluded peninsula beach. Patti was a patient mum, pausing on occasion to let the wee girl catch up!
Despite the loss of Mia’s male pup, nine healthy pups remain on Otago’s coast. Gem, however, who was very pregnant was last seen in late December, still eludes us! She’s out there somewhere, hopefully. With continued searches we may just get our numbers back over the double digit line.
All nine known pups have now been tagged and microchipped by teams of Trustees, DOC rangers and experienced volunteers. This year’s Otago crop of pups are sporting white, coffin-shaped tags in their “flipper pits” ranging in number from 9031 to 9040. The names of the pups will be confirmed in the next few weeks in consultation with DOC, and added to the database of Mum’s family tree, which is available here on our website.
Our tagging missions have attracted quite a bit of media attention lately, with both One News and 3News joining our teams and filming stories. We’re thinking DOC Biodiversity Ranger Jim Fyfe might have to join the Screen Actor’s Guild after all this air time!
The title of the 3 news clip :- “Beachgoers risking the future of endangered sea lion” irked us a little as we have had tremendous support from `beachgoers’ and community groups up and down the coast, but the content of the video clip was on the whole good. If only they had headlined it ` Selfish/irresponsible beachgoers risking future of endangered Sea Lions”
Anyway Check out the videos for yourselves here:
As we’re still keeping an eye out for `Gem’ please do alert us if you spot a female sea lion and/or an untagged pup on the Otago coastline.
If you see one of this year’s tagged pups out and about too, do drop us a line at [email protected] to help us track their movements.
We have thus far discovered no less than 9 pups along the length and breadth of the Dunedin Coast, and two along the Catlins coast. This eclipses last year’s numbers of eight pups around Dunedin and one in the Catlins.
Our coverage of beaches over the pupping periods has been the most intense ever with our new trustees and volunteers diligently checking beach after beach day after day so we could build up a picture of not only where the adult females were but their movements. Aided in no small part by dedicated individuals from the Aramoana community and local communities around Tomahawk, St. Clair, Long Beach, Allans Beach, Warrington, Doctors Point & Purakaunui inlet.
So far we know that 4 are female and 3 male which bodes well for future breeding on the mainland. The remaining pups will be sexed when we get around to flipper tagging and microchipping them in the next week or so.
Our known mothers this year are Mia (Tag No 2591), Patti (Tag No 9001), Zoe (Tag No 2588), Lena (Tag No 3458), Hiriwa (Tag No 9013), Huru (Tag No 9007), Lorelei (Tag No 2578) and Joy (Tag No 9010) of Dunedin, and Matariki (Tag No 9018) of the Catlins, all of whom seem to be carrying out their role as mums with great diligence. The identity of the remaining mums will be determined shortly (they have lost their flipper tags which makes identifying them a little more challenging!)
Stay tuned…we are still on the lookout for two potential mums (Gem and Moana) who may also have pups squirrelled away along the Dunedin coast.
As always, if you spot a female and/or a pup, please contact us immediately at [email protected] or call the DOC hotline 0800 362 468 and report the sighting.
Check out video clip at https://youtu.be/aDX4BqQLsiA
Q: How do NZSLT Trustees & volunteers spend their Christmas holidays?
A: Trudging the beautiful Otago coastline looking for pregnant solo mothers!…..
……of the sea lion kind you understand!
Diligent searching by team of dedicated volunteers has gifted us with 6 healthy pups so far on the Otago Coast with possibility of another few still to locate!
So, the searching will continue with tagging of known pups scheduled for sometime in the next few weeks.
Remember, if you see any females and/or pups while out on Otago/Catlins beaches email us right away at [email protected].
One day to go before the end of 2015 and we have 2 pups already. One to Patti and one to Zoe . (see Otago Sea lion Family Tree for Patti and Zoe’s lineage)
There are eight other females out there on the Otago coast that we have been trying to keep an eye on in the last few weeks. Of course not all might be pregnant but we are hoping for a good 2015/2016 season. Our new team of trustees and volunteers have been shown all the usual haunts by Chairman, Steve Broni and Jim Fyfe from DOC and the searching will continue locally and further afield throughout January to be sure we don’t miss any pups. If you see any females while out on Otago/Catlins beaches email us at [email protected]
NZ Sea Lion Threat Management Plan Stakeholder meeting 16 October 2015
The agenda, presentations, and minutes can be found at the following link
This meeting was very broad and general with very few details for management options.
I will try to summarise some of the main points of the meeting below
Risk Assessment & Workshop outputs
The expert panel made 2 main recommendations:
- Initial model evaluations of threats should focus on using their upper bounds to evaluate whether significant effects are expected at this level. If not, then these insignificant threats can be excluded from further analyses. If yes, then further threat analysis should be based on an appropriate probability distribution of the significant threats between the proposed upper and lower bounds.
This simply means that for all of the threats that were considered earlier in the year the worst case scenario should be considered to assess which threats are the highest priority. These high priority threats can then become the focus of management actions.
- Efforts should be made to better quantify strike rates in trawl fisheries, such as by use of cameras to detect entry of sea lions into nets.In saying this, the expert panel acknowledged the high degree of uncertainty surrounding the efficacy of SLEDs.The new model predicts a continued decline in the sea lion population at the Auckland Islands and the two threats that had the greatest impact if removed were disease and incidental fishing capture. Stefan Meyer has also done some modelling and his model suggests a much greater influence of adult female survival (ie stronger influence of fishing) rather than pup survival (ie stronger influence of disease).
Potential Management Options
Three Management Goals:
- Population goal
- Research and Monitoring goal
- Community goal
Each goal has associated management criteria detailing how progress will be measured
These goals and the management tools available to pursue them were at this stage very general such as marine reserves, fisheries regulations, council bylaws with very few specifics that could be discussed so hopefully we will have another chance to comment before specific recommendations are made to the Minister.
One management option raised several times was translocation. This was mooted as an option for moving mothers and pups on Campbell Island to places less dangerous for the pups. It was also suggested as an option for removing overly aggressive males. I pointed out that translocation has only been successfully used twice for very specific reasons at specific times (ie shifting a mother and pup within the pup’s first week before the mother has gone out to sea). Translocations attempted with other species at other times have largely been unsuccessful.
At the end I registered concern (on behalf of the Trust) over the differences in the two models and stated that as this is the basis for much of the decision making around the seriousness of various threats we ought to try and reach some sort of consensus before going much further or we risk having the same situation as previously with the ‘Breen model’ which became the source of a lot of conjecture. I also stated that we hoped the “Expert Panels” other recommendation about the uncertainty around the efficacy of SLEDs would be followed through.
Shaun McConkey MSc (Trust Scientist)
We now have a project on the Nature Watch website
This is an ideal place for logging your sightings of sea lions when out and about. If for any reason you do not want to log a particular sighting with Nature Watch feel free to email them to us as before at [email protected]
- know how many you would like
- how you will be paying
- what address you would like us to send the calendars to?