Experience: Marine Ecologist
Regions: Otago, Catlins, Foveaux Strait, Rakiura/Stewart Island, Fiordland
Interview Location: Harwood, Otago Peninsula, NZ
Interview Date: 26 January 2016
Post Date: 16 September 2017; Copyright © 2017 Chris Lalas and Steve Crawford
3. WHITE POINTER DISTRIBUTION AND ABUNDANCE
CRAWFORD: Let’s go back to your early days - the Master's thesis and the PhD in and around the Otago Harbour. For all the time you spent in and around that region, you said you didn't see any White Pointers in the harbour, but did the old-timers or any of your mates mention any observation of White Pointers in Otago Harbour?
LALAS: Not that I remember. Definitely Jack, when he caught this big White Pointer [see Direct Encounter below], he was amazed.
CRAWFORD: He was shocked that it was there, or shocked that he caught it, or both?
LALAS: That it was there. You'd know about this ... before the [Dunedin City Council] shark nets and stuff, some people attacked, but I don't know if it was established.
CRAWFORD: Do you know anything about those attacks? Details, locations?
CRAWFORD: Was there an indication that perhaps outside the harbour, around the Otago Peninsula further down, that they were ever seen? Were there ever any occasions?
LALAS: Not that I recall. It sort of exists even today, that up to a decade ago that if you caught a shark in the harbour you were on the front page of the newspaper and heroes for killing marauding sharks.
CRAWFORD: I want to get back to your time when you went to the Chatham islands on that corporate-sponsored trip. For the time that you spent there, was there any discussion about White Pointers?
LALAS: No, but I didn't meet up with a lot of fisherman. I was there at the time of Crayfish boom, and there were a lot of fisherman came over from the mainland to fish Crayfish.
CRAWFORD: Ok. Let’s consider your time down on Stewart Island. Was there any discussion about White Pointers, either in Patterson Inlet or Ackers Point and some of the surrounding islands?
LALAS: Not that I recall.
CRAWFORD: Marlborough Sound region?
CRAWFORD: To the extent that you have experience as an ecologist, as a field conservation biologist - if you had to characterize, at the national level for North and South Island - what regions are known to have White Pointers? What would you think?
LALAS: Stewart Island, the Snares, Auckland Islands.
CRAWFORD: You spent time at the Snares and Auckland Islands. Was there discussion about White Pointers down there? For the people who worked down there, who have experience down there, have there been any surveys or observations? Maybe people were working on Sea Lions and they witnessed attacks? That type of thing?
LALAS: No, but I tagged along with people doing other studies - mostly water chemistry. And the other studies have been winter trips with people studying live whales.
CRAWFORD: Ok. I'd like to shift to Seals and Sea Lions for a little bit. You've got a particular perspective, but you also have a time series associated with your experiences that goes back a fair way. I think you said that around the turn of the century, 1900s - big news flash, Seals present around Otago Peninsula again. And then over the decades from then I'm presuming there was recolonization, growth in the population abundance. And then in the early 1980s, the first reported pupping. From the 1980s to the present, has that population growth increased? And if so, has it gone in a linear fashion or an exponential fashion?
LALAS: Logistically stable. I've got the first record of a pup being born. They've been stable for about 10 years. I think about 25 years from the start to stability.
CRAWFORD: When did protection come in for the Seals?
LALAS: Late 1800s, and formalized in the 1920s or 1930s. But there was an open season in 1948. One year it was an open season, because fishermen were complaining.
CRAWFORD: That there were too many Seals?
LALAS: Fisherman complained that the number of Fur Seals had increased, and they were eating 'their fish.' They stopped catching Blue Cod. There was an interesting paper written about it - its frontispiece had a fishing boat with a Blue Cod fish trap, a fish pot. This guy worked out that what was really happening was that the Blue Cod catch was down, but they'd been exporting the Blue Cod, and the market had fully dropped, and the freezers ashore were full. So they stopped catching them, and looked for someone to blame. I guess what I’m saying is that peoples' attitudes towards Fur Seals, they're not regarded as 'nice animals.' Bit by bit, the furry equivalent to sharks.
CRAWFORD: With regard to the Seal population - at least the animals on the Otago Peninsula - is it something a biologist would recognize as a self-sustaining population on its own?
CRAWFORD: Is there significant immigration and emigration with other populations?
LALAS: You got it - that's the question. For the Seals, once a female starts somewhere, she'll be there every year. She doesn't have a helluva lot of choice - because if she has a pup, she weans the pup at the same time she gives birth to the next one pretty much. So she's stuck there. The same is true of Sea Lions. They are very dispersive before they breed. Definitely. In terms of 10-20 years ago now, there's been quite a lot banding - we've got animals here from everywhere that we've tagged.
CRAWFORD: They're mixing it up quite a bit?
LALAS: Yeah. And the rate of increase in the early years - say the first decade - the rate of increase was too high to be through breeding alone. It had to be through immigration as well.
CRAWFORD: So, a lot of mixing going on. Although, I think it’s an important observation you made that once a female Seal begins to pup, she's locked in for a variety of reasons - not the least of which is that she's got a cross-generational commitment.
LALAS: Yeah. Theoretically, she could move on if she doesn't have a pup or something. I forget what the stable number of pups is, but it’s a few thousand, it’s not huge.
CRAWFORD: At a very general level - the Otago Peninsula south to the Foveaux Strait - when you think of major Seal colonies, what places come to mind?
LALAS: Obviously the Otago Peninsula. The next one down was the last to get going really - Green Island.
CRAWFORD: That’s a major colony?
LALAS: Yeah. My problem is that I haven't been out there for a long time - less than a decade, but last time there was less than a couple of hundred pups there's probably 500 or so now.
CRAWFORD: That's just pups?
LALAS: Yeah. Taieri was just starting up when I stopped doing surveys.
CRAWFORD: Is that a major colony now?
LALAS: I wouldn't think so, no. The Nuggets is a major colony. I've forgotten the maximum number of pups, something like about 500 there. But then it drained down - they were just spreading. I think the next major area is probably Long Point. The next one down is around the corner from Tuhawaiki Island. Then there's [White Head], that’s the next one - actually the bay short of it. And the next is Cosgrove Island; perhaps it's spread south to include Long Point. I would have done my last survey down there maybe ten years ago. The rest, there was really no indication.
CRAWFORD: Really? From Long Point all the way down to Waikawa ... nothing really? Did you do any Seal surveys down around Foveaux Strait, down to Stewart Island?
LALAS: No. But I was involved with a couple of students that had done work at Bench Island.
CRAWFORD: Was Bench Island known to be a Seal hotspot back then?
LALAS: It became one. I think you might even be able to get a first pupping. There’s a publication on that.
CRAWFORD: Would anything else you know about Stewart Island Seals be fragmentary?
LALAS: Yeah. It’s not coherent. But I know some others have done some surveys for that area. One of the long term established spots was one of the islands out about here.
CRAWFORD: The Solanders?
LALAS: Yeah. There was a thorough survey done in this area by Wilson - a paper from the late 1970s, and there was bugger all breeding at accessible places. It’s one of these tricks that they breed in inaccessible places. So, if you only check accessible places, you're never going to find them.
CRAWFORD: Ok. For the time that you did spend in Paterson Inlet on Stewart Island, was there strong numbers of Fur Seals there that you recall?
LALAS: No, I don't recall having seen any. I would have remembered, because that was something I was interested in.
CRAWFORD: When were you there? Paterson Inlet?
LALAS: Late 1970s, maybe early 80s.
CRAWFORD: I want to have a discussion with you about the importance of Seal colonies to the White Pointers. There's been a tremendous amount of discussion about where the White Pointers are, and what they're doing there, and the changes over time, and the relationship with other important changes in the ecosystem. From your experience, and the people you have worked with and the old-timers, was there a really strong, tight correlation between the distribution of White Pointers and Fur Seals - in particular the pups?
LALAS: That’s what I've been thinking about since you called, and I would say no. What's happening with Sea Lions ... the first Sea Lion birth in Otago in modern times was 1991, I think - and I was studying them for diet. For about 15 years it was me and one of my students. I've kept up on the diet stuff. What was happening starting in the mid-90s, was that adult male Sea Lions eat Fur Seals, and it's really distinctive damage on what you end up with. You end up with bits washed up.
CRAWFORD: When you say Seals, do you mean Seal pups or Seal adults, or both?
LALAS: The biggest I've had is a sub-adult male. I looked up what its weight should be for its length, it was over a meter and a half long - it was near full grown, and would have weighed 60 kilos. What happens, you can tell at distance the body's degloved, which means the body's been ripped apart, essentially the skeleton is largely intact, but everything has been eaten out of it and the skin by the time it washes up. It tends to turn up over the head, so it’s like a cape. Imagine an animal that’s been stripped of all its body innards, and its skin is just loose. I was going to say the Sea Lions eat Seal pups whole, but they don't eat them whole - they break them up, but they'll eat the whole thing. For example, I've got vomited skulls of pups. It must be quit something to swallow that. But that's also classic. Once they hit two or three years old it’s very distinctive canines through the skull, so that they are almost inevitably killed by a bite to the head. When I clean up the skulls, you can see the puncture wound. I haven't seen anything in terms of Fur Seal remains that don't fit that profile. If they're being attacked by a shark, the damage would be quite different. There would be bits turning up, but they're not going to be degloved. They might be through time by Gulls.
CRAWFORD: There are going to be different types of cuts?
LALAS: There's no such thing as a cut on a bone by a Sea Lion.
CRAWFORD: I think this is an important part of the conversation. First of all, when you get Fur Seal remains after a Sea Lion attack, where are you getting these remains? Are they washing up on shore?
CRAWFORD: In the time that you've been doing these surveys, have you ever seen anything that you would suspect was the result of a shark attack on either a pup or an adult Seal?
LALAS: Here I can be quite categorical because I document, I have to collate the evidence. Where I'm lucky is that they end up eating quite a lot of stuff and vomiting it up - pup skulls and stuff. I can see what it is - well there are three sources. One is vomit, one is where a degloved body has come up, and the other is where myself or somebody else has seen a Sea Lion attack, and then the body washes up and we go out on the boat and get pieces.
CRAWFORD: Before we go on, we have to recognize a White Pointer attack on a Seal could by nature be a very different thing. I'm not sure what extent we'd expect White Pointers to regurgitate anything, or where they would do that regurgitation. But the helpful thing about your classification is that there are regurgitations, remains and observations. In terms of regurgitation, for the sake of argument we're just going to remove that for a second. White Pointers, if they do any regurgitation, they wouldn't do it necessarily along the coastline where they attacked.
LALAS: This is without question Sea Lion regurgitation - something that’s washed up. Whereas a degloved body or bits are washed up.
CRAWFORD: Ok. Let’s go to the remains. Whether it was regurgitated or not, the point is that when a White Pointer takes a Seal there can also be bits and pieces. For instance, when I did interviews at Curio Bay, there were several Seals, and they were quite known to the local people, and a shark took one of the Seals. Then there was another attack the same year. And then the third and fourth attacks on Seals in the next year.
LALAS: This is Sea Lions you're talking about?
CRAWFORD: No. White Pointer attacks on Seals.
LALAS: I would be cautious there because there's a difference in behaviour between Fur Seals and Sea Lions.
CRAWFORD: The important part was that there was a flipper remaining. The witness saw the attack, he called it into DOC, somebody came down and did a beach scan. They found remnants, including a Seal flipper, and they buried it. Whether it was the same White Pointer or whether perhaps there were other sharks, there was a series of attacks on Seals on rocks, adjacent to the rocks. In that case, there were very clearly remains from the attack. And in that case, you have the ability, potentially at least, to recognize incisions. If there were White Pointer attacks on Seals, along the places where you have done surveys and found remains, these were washed up on shore?
LALAS: Yes, that’s the norm.
CRAWFORD: I suspect if you were finding those, and there were bits and pieces of Seals, there's a good chance you would have found at least some that resulted from White Pointer attacks?
LALAS: Yes, if the shark is doing what the Sea Lions do - which is cruise the colonies, then you would expect bits to wash up.
CRAWFORD: And that’s the point that I'm trying to come to. You've spent a significant amount of time assessing nearshore conditions, specifically with regards to predation on Seals by Sea Lions.
LALAS: But collecting the evidence would indicate that it’s not sharks doing so. The only injury on bone that I've got are the puncture wounds. The older the Seal, the thicker the skull, and the clearer the marks.
CRAWFORD: Out of all that work, did you ever find a substantial amount of evidence that could have been shark attacks on Seals?
LALAS: Nothing. But keep in mind we're just talking Fur Seals here, because we haven't started on Sea Lions.
CRAWFORD: Ok. For other professionals, other people who you think would be knowledgeable and credible Seal biologists - have they done similar types of work and found evidence of White Pointers feeding on Seals?
LALAS: I'm not recalling anything.
CRAWFORD: Let’s get back to the Sea Lions. What do you know about interactions between Sea Lions and White Pointers?
LALAS: It looks like White Pointers could be a major cause of mortality down south.
CRAWFORD: When you say 'down south,' what do you mean?
LALAS: Auckland Islands, Campbell island, and the Snares. It's normal when you walk around to see Sea Lions with shark damage. Whereas up here I recall only one, it was a flipper - you could see the line of the teeth.
CRAWFORD: But that’s the exception in this region?
LALAS: Up here, yeah. But it’s not unusual down south and that’s where I mentioned Louise's contact, because I'm pretty sure she's quantified it.
CRAWFORD: Louise Chilvers, working out of Massey University?
CRAWFORD: Ok. So, based on your discussions with other professionals, you have a strong feeling that White Pointers can be a major source of mortality on Sea Lions in the sub-Antarctic islands?
LALAS: Yes. But given that where we see an animal with shark damage on it, it means it got away. We don't see the ones that didn't get away.
CRAWFORD: Would you predict that the number of instances where you see a Sea Lion with scars would be correlated in some sense to the number of Sea Lions that were taken by White Pointers? Those that didn't get away?
CRAWFORD: Is it the case that people you know who are working in the sub-Antarctic islands - have they seen White Pointers preying on Sea Lions as well?
CRAWFORD: Observed attacks there, but not so here on the Otago Peninsula? Is it also very low in terms of scarring here?
LALAS: Yes, but also keep in mind the number of Sea Lions up here. Let’s say they were eating 1 in 100 Sea Lions a year. We've only got a hundred Sea Lions here, so you're not going to get the same kind of observations of attacks or scarring.
CRAWFORD: Let’s put things in perspective. What’s the population abundance of Sea Lions down on the sub-Antarctic islands?
LALAS: Oh, it’s probably 8,000-10,000 animals.
CRAWFORD: So, two orders of magnitude higher?
LALAS: Yeah. And you could walk ... in a day you could see several hundred animals there. I know that Louise, one of her ambitions was to quantify the number of animals showing damage, and what that damage was.
Copyright © 2017 Chris Lalas and Steve Crawford