New Start For the Sea Lions

Forest and Bird, Issue 300, 1 May 2001, Page 14

New Start For the Sea Lions

SHAUN McCONKEY

fter being driven from our shores Maori hunters and European sealers, New Zealand sea lions are coming back from the subantarctic. Mostly males, the population around our southern coast may now exceed 100. This return of the threatened sea lion has received a welcome boost with the recent birth of three pups, adding to the previous six pups already born on the mainland. What is remarkable is that all nine births are descended from one female. She is simply called ‘Mum’. Mum was first seen in Otago in 1991 at

four years of age. Having been born on the Auckland Islands she swam close to 650 kilometres to reach Otago. She is one of only five or six females to make the journey. Unlike Mum, most female sea lions are rarely seen. Due to this lack of females the first successful birth of a sea lion pup on the mainland did not occur until Mum gave birth in the summer of 1993-94. Males, on the other hand, have been increasing their numbers in Otago, from infrequent sightings as early as the 1950s, to approximately 100 resident animals in the year 2000.

Mum is now a regular on Otago Peninsula and has given birth successfully to six pups; four daughters and two sons. Mum’s first four offspring have survived and continue to live on Otago Peninsula where they were raised. Sadly last year’s pup was found dead on Otago Peninsula with no obvious cause of death. Her most recent pup, born in January 2001, went missing shortly after he was discovered and there is little chance that he will survive for long away from his mother. There is some concern that these recent breeding failures may cause Mum to abandon the area.

After 100 years or more, New Zealand Sea lions are breeding on the mainland again; but they need help, according to

All photographs with this article are by SHAUN McCONKEY

All this serves to highlight how fragile the breeding status of sea lions on the mainland may be. On the Auckland Islands and Campbell Island, large "beachmaster’ males defend territories containing groups of females and their pups, which are born in December or January. In Otago, Mum and her two breeding daughters are solitary breeders and must care for and protect their pups on their own. Added to this, both pups and adults face new dangers when living near human habitation. The main danger is from uncontrolled dogs, which may find sea lion pups hiding

near the beach where they have been left while their mothers go to sea to feed. Another danger is from well-meaning members of the public who sometimes pick up a pup, thinking it has been abandoned. Mothers return to the area where they left their offspring, calling until they hear a response. Once they meet, mother and pup will sniff one another to make sure they have the correct match. If pups are not returned to the place they were removed from, their mothers will not be able to find them when they return and the pups will starve. Adult sea lions are at times on the receiving end of human aggression as they are often condemned for competing with local fishers. They feed within the range of the continental shelf, usually on or near the bottom, focussing on species such as barracouta, jack mackerel, flatfish, octopus, and cod. In the recent past sea lions have been shot, rammed by cars, and clubbed to death, in Otago. Most sea lions have so far avoided beaches heavily used by the public, but if numbers continue to increase there are likely to be more encounters and sadly more sea lion deaths. The increasing popularity of ecotourism in the region will

also lead to further ‘interactions’ which will need to be carefully managed. There is little reason for people to fear sea lions as long as they are given a wide berth; the Department of Conservation recommends a distance of at least 10 metres. Sea lions are seldom frightened by people, and their tendency to sleep when ashore often makes people complacent. This can be dangerous as sea lions have very quick reflexes and can move rapidly over short stretches of beach. When faced with an uncertain situation, sea lions will often put on a display of aggression, but seldom do more than sit up and ‘roar’. When sea lions are in a group, one

Sea lion or fur seal

ur seals and sea lions are sometimes mistaken for one another but have several physical and behavioural differences.

Sea lions

Blunt nose Larger (max 400kg) Adult males have a mane of longer hair around neck and chest Coarser, less dense fur Hind flippers move independently Unafraid of people Prefer sandy beaches Feed over the continental shelf

Fur seals

Pointed nose Smaller (max 200kg) Adult males have no mane Finer, denser fur Hind flippers move together Afraid of people (unless used to them, or territorial breeding males) Prefer rocky shores Feed at the edge of the continental shelf or beyond

‘With the birth of another three pups on the mainland this summer, one of which has gone missing from a very public beach with dog access, I think it is important to let people know their current situation. — Shaun McConkey.

Female sea lions

emales can be distinguished adult males as they are generally light grey or pale brown in colour. As adults they are much smaller and lack the mane of longer hair around the neck which is characteristic of males. Young males can sometimes be light in colour and, being smaller than adults, are often mistaken for females.

New Zealand Sea Lions at Risk in the Subantarctic

"he greater number of New Zealand sea lions breed on the subantarctic Auckland Islands some 600 kilometres south of mainland New Zealand. ~ There they are under pressure from commercial fishing, particularly for squid, and Forest and Bird has been active in seeking better protection for them. In 1982, fishing was forbidden within 12 nautical miles of the island group, and in 1997 an Auckland Island Marine Mammal Sanctuary was declared covering this area. Forest and Bird wants this sanctuary extended out to 60 nautical miles to make it more effective. Sea lions still get caught accidentally: about 80-100 a year. In the last five years the fishery has been closed four times as the accidental "by-catch’ gets close to or exceeds the limit set by the Minister of Fisheries. The limit has been set at between 60 and 80 sea lions every year since 1992. When this limit is reached the Government closes the fishery for the season. Despite this, it is believed the number of sea lions killed has still exceeded 100 animals a year, in several years, due to delays in closing the fishery. This figure is based on extrapolations from Ministry of Fisheries observers — the fishing industry is believed not to accurately report the number of sea lions killed. This year, for the first time, there will be 100 percent coverage of the catch by observers on the ships. Under pressure from Forest and Bird, and the Department of Conservation, the fishing industry is now trialling a net-exclusion device that may stop sea lions being drowned in trawl nets. It is hoped this year it will be possible to determine whether the net device ejects live, or dead, or injured sea lions. Forest and Bird has also called on the fishery to use an alternative fishing method, such as jigging, but there have been industry claims that the subantarctic waters are too rough for this technique, despite the fact they have fished there in the past with good catch rates. A population management plan for the sea lion will be released later this year, sertting out proposals to protect New Zealand sea lions and build their population to a non-threatened state. The plan will be open for public submissions and be binding on the Minister of Fisheries. — Barry Weeber, Forest and Bird marine specialist.

disturbed animal can affect the whole group, increasing agitation or aggression. Also, during the breeding season, which extends from November through January, males may become more aggressive and territorial. A greater distance should be maintained in these situations, or if animals are active. Mum’s first two daughters, ‘Katya’ and ‘Leone, have now followed in their mother’s footsteps, remaining on Otago Peninsula and giving birth to pups of their

own. While this breeding is at the limit of their current distribution, archaeological evidence suggests that historically sea lions were not only present, but also bred at many mainland sites, including the northern ends of both the South and North Islands. Sea lions were eliminated from the mainland by hunting pressure from Maori and early European hunters. Both sea lions and fur seals were protected by 1893, at which time they were largely restricted to islands in the

subantarctic. Unlike fur seals, which have spread right around the South Island and onto the North Island, sea lions have remained severely restricted in their distribution. Sea lion breeding occurs, almost exclusively, on a few subantarctic islands — on Dundas, Enderby and Figure of Eight islands in the Auckland Islands, and on Campbell Island. Outside the subantarctic, sea lions are generally limited to sandy beaches on Stewart Island and the Otago coastline, with strongholds in the Catlins region and on Otago Peninsula. Due to their limited breeding range (two breeding colonies in the Auckland Islands produce 90 percent of all pups), New Zealand sea lions are currently classified as ‘vulnerable’ by the World Conservation Union. The vulnerability of the sea lion population to infection or disease, caused by this limited distribution, was highlighted during the 1997-98 summer when more than 50 percent of pups and an unknown number of adults died. Most deaths were caused by a bacterial infection of unknown origin, though some pups probably died of starvation after being abandoned by sick mothers. It is believed a combination of environmental factors may have lowered the sea lions’ immunity to a naturally occurring, normally non-lethal, bacteria. No evidence of similar widespread illness has been found since. The number of sea lions at the Auckland Islands has been recently estimated at

11,000-14,000. There is concern that the number of sea lions caught as accidental bycatch in the Auckland Island squid fishery may be affecting the ability of the population to recover. Current government policy is focusing on reducing the bycatch enough to allow the population to increase and expand its distribution. These sea lion births on the Otago mainland may herald the successful establishment of a breeding colony outside the population base at the Auckland Islands. A report of a breeding female in the Catlins is currently under investigation. The lack of females migrating to Otago makes those already here even more important. Katya’s most recent pup, born this year, is a female which is likely to

remain and breed in Otago. The future of mainland breeding rests with females like Mum, her daughters, and her granddaughters being able to survive and produce more female offspring to continue the population expansion. The greatest threats to mainland colonies are from uncontrolled dogs attacking pups, and unwarranted acts of violence by people. With careful management and public support, however, breeding should continue, and sea lion pups on the mainland will become a common sight after an absence of at least 100 years. — SHAUN McCONKEY completed an MSc on the photographic identification of sea lions in 1997, and continues to watch their progress on Otago Peninsula.