Friday, December 5, 2014

Understanding the Elusive: Conservation in an Rapidly Changing World – PART 1

Deciding which species “deserve” the most resources and attention in terms of conservation can be a contentious issue at the best of times. Members of the general public tend to favour protecting the cute and cuddly however, are these characteristics really the most effective way to decide how to direct our efforts? Using a publication written by Chapple et al. (2011) and estimating white shark populations in California, USA, as a case-study, this two-blog series aims to highlight:

  • The difficulties of estimating population sizes of marine species
  • The importance of the production of the most accurate information possible from the scientific community, and
  • The impact of these factors on the success of conserving endangered marine species.

The Challenges of Modelling the Population Size of Migratory Marine Species

In 2011, a study completed and published by Chapple et al. estimated that the central California population of white sharks consisted of only 219 mature and sub-adult individuals. Their study was conducted over a three year period in two focal areas (both of which are well-established seal rookeries) around the Farallon Islands and Tomales Point in which white sharks are known to aggregate. As the dorsal fin is the equivalent to a ‘fingerprint’ for individual white sharks, photographs of dorsal fins were used by Chapple et al. to generate abundance data of the number of individual white sharks seen across these two sites throughout the study period. Population estimates were then subsequently modelled for sharks in this area.
In order to model these population estimates, Chapple et al. made five key assumptions:

  1. Their study white shark population was closed
  2. There was homogenous sampling of animals and all individuals had an equal probability of capture
  3. The “tagging” process did not influence the chance of recapture
  4. There was zero “tag” loss
  5. Photo-identifications of white sharks at these two aggregation sites represented a random sample of the central California population

If correct, the low estimates of white sharks presented by Chapple et al. justifiably raised concerns for the status of the white shark population in California and the ENP. Just as with any scientific publication however,

“it is important to consider the potential for methodological flaws and assumption biases that may have resulted in an under-estimation of the actual population size” (Burgess et al., 2014)

In June of 2014, George Burgess and his colleagues published the results of an important re-evaluation of the size of the white shark population off of California, USA, based upon a data set collected at the same sampling locations as Chapple et al.’s 2011 study (Jorgensn et al., 2010). The differences in the estimates of the white shark population size off of California between the two studies was staggering, with Burgess et al.’s estimate (2014) indicating a minimum all-life stages population size of over 2000 individuals.
Burgess and his colleagues found that all five key assumptions made by Chapple et al. (2011) had been violated, resulting in an underestimation of the white shark population in this area.

Assumption #1: Closed population 

By assuming that the study population was closed, Chapple et al. effectively assumed that all mature and sub-adult white sharks would return annually to the seal rookeries of their study. However, considering that:

  • Multiple examples in the literature have shown that most sharks do not return annually to particular aggregation sites
  • Some sharks within the ENP may be located within the region but not in either of the two study areas and therefore will not be accounted for in the study
  • The number of unique individuals identified by Chapple et al. increased each year (suggesting an immigration of sharks during the study)

It was concluded by Burgess et al. that both the existing literature and Chapple et al.’s own data demonstrated that the study population was in fact open over the three years of data collection; thus violating a key model assumption.

Assumption #2: Homogenous Sampling of Individuals

In more layman’s terms, Chapple et al. assumed that every shark had an equal chance of being sighted, and that sharks at the two aggregation sites which they collected data mix in a homogenous or “equal” manner with each other.
Although it is well known that white sharks do show site fidelity to seal aggregation sites or rookeries, research has also shown that individual sharks show preference to specific locations and may restrict their movements as a result of this; limiting the mixing of individuals over small spatial distances. Based on these findings alone, it is clear that Chapple et al. should not have assumed homogenous sampling as they in fact had an increased probability of re-sampling previously observed sharks at each of their sample sites. This assumption violation results in a low bias towards their population estimates.

Assumption #3: Tagging method does not affect subsequent chance of sampling

One of the main issues with using photo-identification to model white shark populations is that it requires the sharks to be lured and baited to the surface where they can be photographed. It is therefore assumed that all sharks have an equal probability of being attracted, and that all sharks in the area will have an equal chance of being attracted again. However:
  • In comparison to acoustic detections done by the Oceans Research team in Mossel Bay, photo-identification has been found to show the lowest probability of detection and tended to underestimate residency times and local abundance for white harks
  • Intra-specific dominance patterns between large and small sharks may exclude some individuals from the area or inhibit their approach to the surface, leading to greater probability of low quality dorsal fin photographs and under-reporting of shark numbers
  • Some individuals may learn that the bait does not lead to a food reward through negative attraction conditioning. These “trap-shy” sharks will therefore have a smaller probability of attraction during subsequent sampling events and be less likely to be re-sighted.
Although being unable to re-sight previously ‘tagged’ sharks may lead to population over-estimations, the latter two factors combined would lead to an underestimation of white shark population size, which is what Burgess et al. believes to be the case in Chapple et al.’s study.

Assumption #4: Zero tag loss

Unlike a fingerprint, the primary characteristic markings on the dorsal fin of white sharks – the pattern of notches on the trailing edge of the fin – have the potential to change with time. Although this “tag-loss” as a result of marking changes does not necessarily result in over-estimation of population size, it introduces the probability that individuals can be present but not correctly identified; violating the fourth assumption made by Chapple et al. (2011).

Assumption #5: Random sampling of the central California sub-population using photo identification

Burgess et al. commented in their review of Chapple et al.’s study that this was the most serious of all assumptions violated by the research group. As white sharks in the Californian region have been observed to reside predominantly at a single aggregation site and less often at others, the sharks sampled by Chapple et al. cannot and do not represent random samples of the central California white shark population. Instead, sampled sharks represent only sharks that visit these two aggregation sites either a single time or consistently over the study period. This violation is further compounded by the lack of sampling elsewhere in this oceanic region, such as the known white shark aggregation site of Año Nuevo Island which was excluded from population modelling for ‘logistical reasons’.

This post highlights how difficult it can be to not only collect abundance data for marine species such as white sharks but also how difficult accurately modelling and monitoring their population sizes can be. As Burges suggested models cannot be applied blindly, but careful consideration of the assumptions behind is urged.

But what does this all mean in terms of conserving the white shark and other marine species? Does it really matter if the numbers aren’t quite right?

Keep posted for my next blog outlining the issues of protecting, conserving and monitoring marine species and why it is important that the community is supplied with the most accurate information possible in regards to population sizes and dynamics.

Lauren Peel
Oceans Research P.I. and Field Specialist

Burgess GH, Bruce BD, Cailliet GM, Goldman KJ, Grubbs RD, Lowe CG, Macneil MA, Mollet HF, Weng KC, O’Sullivan JB (2014) A Re-evaluation of the Size of the White Shark (Carcharodon carcharias) Population off California, USA. PLoS ONE 9(6): e98078.

Chapple TK, Jorgensen SJ, Anderson SD, Kanive PE, Klimley AP, et al. (2011) A first estimate of white shark, Carcharodon carcharias, abundance off central California. Biol Lett 7: 584-583.

Jorgensen SJ, Reeb CA, Chapple TK, Anderson S, Perle C, et al.. (2010) Philopatry and migration of Pacific white sharks. Proc Roy Soc B 277: 679-688.

Delaney DG, Johnson R, Bester MN and Gennari E (2012) Accuracy of using visual identification of white sharks to estimate residency patterns. PLoS ONE 7(4): e34753. doi:10.1371/journal.pone.0034753

Thursday, August 14, 2014

To fence or not to fence, that is the question!

Conservation is the responsibility of the state, but Africa is a poor continent, and as a consequence conservation in Africa has unique challenges, as Governments can’t fulfill the role of funding the conservation efforts. National parks and reserves have to find a way to get an income to support their conservation efforts.

Tourism has the potential of creating funds, but not enough to cover all expenses. Non-governmental organizations such as WWF, IFAW and CI to name a few contribute immensely to the conservation effort, but still more funds are needed, which bring me to the controversial topic of utilization of natural resources by the local populations around conservation areas.

I am going to use a few examples I have encountered over the last couple of years, working in southern Africa.  South Africa is the only country where National Parks are totally fenced and this is in the process of changing, with the establishment of Trans Frontier Parks. The fence between Limpopo National Park in Mozambique and Kruger National Park was removed a few years ago to use an example. Fencing is an agricultural practice and once a Reserve or National Park is fenced, we have to manage it more intensely as we have curbed certain natural processes. Numbers of game can increase to numbers higher as the carrying capacity of the area. In times of drought water and food supplements has to be supplied as natural migration routes was blocked. This can have a negative impact on the vegetation, and to keep damage to the vegetation to a minimum we must start inhumane practices such as culling to control game numbers.

So what is the alternative? Will it be possible for humans and wildlife to coexist and to utilise the same resources? Prior to the arrival of Europeans on the Dark Continent this was the practice and did humans and wildlife indeed coexist. But we don’t live in Utopia anymore and alternative strategies are needed. 

Here are a few possible alternatives.  Kafue National Park in Zambia, 22 400 km² the second largest park in Africa is unfenced. Around the park is a buffer zone of 10 to 15 km wide where utilisation of resources are allowed by the local population. Hunting concessions are sold to professional hunting operators by ZAWA and the income created is used for conservation and for creating an infrastructure in the local population adjacent to the park. All meat from hunting goes to the local population, as well as some of the hunting fees. Tourist operators build lodges in the buffer zone which create jobs for the locals, as well as chances to sell curios and fresh produce to tourists and lodges.

Botswana, where wildlife and humans coexist to a certain extent.  Along the western side of the pan handle just above the Okavango Delta, humans and elephants coexist. Humans farm along the river and go through their daily tasks during the daylight hours and once the sun sets spend the evenings indoors. The elephants on the other hand spend their days, 20 – 30 km north of the river, and once the sun sets move down to the river and spend their evenings on the banks, drinking and foraging. They leave before sunset and move back along corridors between homesteads. There are some crop raids, but other methods to keep elephants out of fields such as chilly plant hedges around crop fields and the burning of chilly balls, (a mixture of elephant dung and chilly plants) are used.

So is there still space for fences in conservation?A recent publication in Biological Conservation: 176 (2014) 162-171, Fencing protected areas: A long-term assessment of the effects of reserve establishment and fencing on African mammalian diversity by Massey et al., in Aberdare National Park in Kenya. This study used long term data sets at two sites in the park collected over approximately 50 years. The two sites, Tree Tops on the perimeter, and The Ark away from the perimeter of the park. The park was partially fenced in 1991 enclosing the two study sites.They looked on the effect the fence had on wildlife populations. Their findings are very interesting, initially the fence had a positive effect on wildlife, and game numbers increased at Treetops. Although there was fluctuations on species richness at both sites, the Ark was much more stable during the study. Comparing the total mammalian biomass at both sites, the same pattern was seen, a decline at Treetops and stability at The Ark. The fence created an edge effect that had a negative impact on game numbers, species richness, on the other hand, at the Ark, away from the fence it was stable throughout the study. The fence initially kept the impact inside the park to a minimum, and hence game numbers increased, but due to a lack of maintenance and illegal entrance,the local human population encroached into the protected area.This led to illegal practices such as logging, the making of charcoal, and cattle grazing which had a negative impact on game numbers and species richness, proof that a fence is only successful in protecting wildlife if managed properly.

Private Game Reserves with potentially dangerous animals such as lion and elephant in highly populated regions that are focused on the tourist market, must obviously be fenced. This is to keep the danger away from the local population and to protect the livestock of their neighbors. After all small reserves are managed intensely, and can be treated as an“agricultural” practice in the region, with fence maintenance as a priority.


Another method might be to fence in the people in and to give wildlife the freedom of movement. The farmers at Panamatenga just south of Chobe National Park have done that. The whole farming area is fenced in with an electric fence and the wildlife can move around the farmland. Ask anybody who have ever been to Kasane in northern Botswana, and they will tell you, the elephants move through town at night, this is a prime example that humans and wildlife can coexist, we just have to adapt our behaviour slightly. After all it is just good manners to be considerate to your neighbors habits and needs.
To conclude, fences have a role to play in conservation. In areas of conflict between wildlife and humans, fences can form a barrier protecting humans from potential danger and at the same time protect conservation areas from human impact.
Let us rather try to find ways to move away from fencing,especially in larger reserves and National parks,  fences are expensive and difficult to maintain,  and sometimes not successful in protecting wildlife and humans alike. Mozambicans are allowed to stay within the boundaries of their  National Parks and Reserves, maybe that is something to look at, as long as there is not an over utilisation of resources, we can all live in harmony, maybe Utopia once again!

Jo Fourie
Oceans Research
Wildlife Research Unit

Thursday, July 31, 2014

Wildlife Research Unit - a lifestyle

Imagine a typical day in the life of a Wildlife Research Intern at Ocean’s Campus...

Before 8:30am, you have already scarfed down breakfast and are finishing off the last bit of toast in the passenger seat bound for Gondwana Nature Reserve. Reference book in hand, you spot Orange-breasted Sunbirds and yellow Cape Sugarbrids in the entrance to the 14,000 hectacre park. Cheetahs are the target animal for the morning however. You assist expert ranger Jo Fourie in triangulating the exact location of two collared bachelors not far from the visitors’ lodge. This requires tracking by foot and wheel as you make your way through savanna grasslands and up fynbos knolls. Inspect some scat, study a faint print in the track (rhino, you deduce), scout the raptors trolling the plains, then makeshift a pond-side camp for a lunch of your own. The afternoon consists of another game drive, this time to record the behaviors of giraffes within a predator reserve. Rays of sunshine filter through the window; you can feel them bathing down your neck and arms as you follow the patterned long necks with your binoculars. On the short ride back to campus, you chat with Jo about the day’s data, but also about the wonders of ecology, the folktales of animal behavior, and the finer details of life. Another day, another adventure. One thing is certain: Tomorrow will be entirely different.

The Wildlife Research program debuted in May, 2014 as an addition to the suite of eight other educational internships offered by Oceans Campus, in Mosssel Bay, South Africa. It sets itself apart as the only program dedicated solely to developing the skills necessary for running a terrestrial research project. Interns learn various scientific methods for compiling and analyzing professional level research on wildlife species. Projects may involve birds, insects, small animals, and/or large animals like caracals, rhinos, and elephants.

Two years in the making, the program kicked off this month with a bang. First-time intern, Alex Raposo, spent a full week camping in the African bush with senior instructor Arno Smit. There, she learned the technical as well as survival skills that would help her understand the bio-diverse environment on a profound level. When she wasn’t around the fire or procuring dinner, she was tracking animals, learning to identify their footprints by size, shape, and impact. She also studied various scat samples, practiced how to best approach animals, and even got a tutorial on how to properly defend herself in an adverse wildlife encounter.

“I recommend it to anyone who plans to spend a significant time in the bush,” said Alex. “And it was just fun too.”
One highlight for Alex was witnessing the release of a male rhino into the park. It was the second day of her program. Alex watched from a safe distance as rangers assisted the large bull into its new home. The excitement was high for the rhino reintroduction, but also cautious, for rhinos are a controversial issue in South Africa due to rampant poaching. Alex was happy to report that the male rhino had been spotted mating with a young female less than a week into his transition. Perhaps this means the 2015 interns will even get to glimpse a rhino calf.
No day is quite the same for Alex, but each day builds on the last. She has become an expert for example, in the telemetry used to map the approximate locations of collared animals, especially cheetah and rhino. She has also assisted the senior instructors in collecting data for a project on giraffe behaviors. The hypothesis revolves around whether the giraffes in Gondwana, where predatory lions share the same park, act differently than giraffes in predator free parks. Other projects include trapping small mammals to study genetic diversity and survival rates, camera trapping for nocturnal activity, and crunching bird data to research whether or not there exists a difference in diversity between nature reserves and local farms.

By the end of her time in Gondwana, Alex will have composed a research proposal of her own design. She plans to return to the University of Toronto where she will be a senior this year in order to complete her degree in Biodiversity and Conservation Biology.
Meanwhile, Arno and Jo will be busy going “bush” with a host of new Wildlife Research interns over the next couple month (three for June and six for July). They will continue research started with Alex and begin new projects as they arise. With the start of winter bloom budding the beauty of fuzzy Pretoria and lavender hued Ericas across the Western Cape, it is a promising time for Wildlife Research interns wanting to do some blossoming of their own through a bit of adventure, a lot of learning, and more than touch of fun. 

Jordie Ricigliano

Monday, June 30, 2014

Sharks International- Durban 2-6 June 2014

Earlier this month the KwaZulu-Natal Sharks Board in Durban played host to the 2ndSharks International conference; a gathering of the world’s leading shark and ray researchers to update and share the results of their current findings. Oceans Research Director Enrico Gennari and I were in attendance and presented some of our current research to over 270 delegates from 37 countries. The conference was an overwhelming success with 169 oral presentations and 52 posters spread throughout the weeklong event.  David Shiffman, expert on all things Twitter, provided the ‘official’ reporting from the field, and many more contributed to over 7000 tweets at #Sharks14. For those of you that missed out on the action, David has taken a break from the conference dance floor and compiled a collection of selected tweets from the event here. What follows is a brief recap of the event.

The conference was opened with a message from MEC for Economic Development and Environmental Affairs, Michael Mabuyakhulu who reiterated the value of shark education for the economy of South Africa, and encouraged all in attendance to visitand spend their foreign currencies at Durban’s magnificent Gateway Theatre of Shopping. Dave Ebert, of the Pacific Shark Research Center in Moss Landing, California was the plenary speaker for the day and reiterated the value of morphological taxonomy in light of emerging modern tools like genetic microsatellites. Ebert has close ties to South Africa having completed his PhD studies at Rhodes University, and noted that southern Africa is one of the world’s hotspots for shark and ray biodiversity with a rich history of species discovery, but a surprising lack of young  scientists currently training in species taxonomy. The rest of the day saw many of our colleagues presenting their work on white sharks in South Africa, with notable talks from Alison Kock presenting the culmination of her PhD on sexual segregation in False Bay, and Enrico Gennari, presenting his PhD on the metabolism and behaviour of the white shark in Mossel Bay.

Despite the unsuccessful efforts of a small group of protestors to disrupt the proceedings of Day 1, Day 2 began unimpeded with a plenary from Demian Chapman. Chapman shared his team’s genetic work on identifying species and populations of sharks traded on the shark fin market, noting that the potentially endangered guitarfish could be one of the highest value species on the market. In addition to identifying which populations are most affected by the fin trade, Chapman’s team also trains customs officials to identify fins that are illegal to trade. Notable talks from Day 2 included those from the genetics department at Stellenbosch University, and the plethora of Telemetry talks from the likes of Steven Campana, Philip Doherty, Neil Hammerschlag, and Christoph Rohner. And naturally, my talk on the lifetime of SPOT tag technology her in South Africa, for which we received some coverage in the local paper.

On Day 3 the organisers saw fit to provide us with a much needed mid-conference break from the overload of day-time academia and night-time socialising. Many delegates spent the day diving at nearby Aliwal Shoal or on game drives at some of the area’s private reserves. Rumours of an out-of-season Whale Shark spotting spread quickly, leaving those that opted out of any tours green with jealousy.

Day 4 picked up right where we left off on Tuesday with a plenary from Colin Simpfendorfer of James Cook University in Australia. Simpfendorfer shared recent findings that upwards of 25% of shark and ray species are threatened with extinction, and almost half are listed as ‘Data Deficient’. Much of the focus has been on shark populations but rays are bearing much of the brunt. #RaysNeedLove2. For some parts of the developing world, shark fishing is a matter of survival, and some of these species can be sustainably fished, but only with sound, science-based management. Ultimately it is a lack of scientific understanding that makes fisheries management difficult. The days professional and student talks were dominated by the fisheries theme, but the standout talks for me were those from Shaun Collin’s lab of sensory biologists at UWA: Kara Yopak, Ryan Kempster, Laura Ryan, and Lucille Chapuis. And of course our colleagues in False Bay and Gansbaai speaking on the population ecology of the white shark.

And lastly, Day 5 began with an entertaining plenary by University of Windsor’s Nigel Hussey who spoke about the growing field of trophic ecology. Stable isotopes in elasmobranch tissues can be used to reveal the entire story of a shark’s diet, revealing a much wider range of diets on both the individual and species levels. The first Sharks International conference in Cairns, Australia featured 2 presentations on Stable isotope research. This year there was an entire plenary and themed section on trophic ecology research. Friday also saw an entire presentation section dedicated to research on the severely threatened sawfish, perhaps one of South Africa’s first marine extinctions. Other notable talks were those on shark attack mitigation and shark control measures, with a particular standout for me from Francesco Ferretti and his talk on modelling shark attack data along the California coast.

The close of another successful Sharks International was celebrated Friday night with a gala dinner and dancing, where awards were handed out, and the announcement was made that the Brazilian Shark and Ray research community, SBEEL, will be the host of Sharks International 2018. Looking forward to seeing you all again in 4 years in João Pessoa!

Dylan Irion

Friday, June 13, 2014

Wildlife Research Unit kicks off

Oceans Research has evolved and crawled out on land, and so we have started with land based research with one intern and five projects. The studies were conducted on two private game reserves in close proximity to Mossel bay. The small mammal survey and bird surveys were done at Botlierskop for safety reasons, as the Lion on the reserve is kept in an enclosure and not free roaming as is the case on Gondwana Game Reserve.

 The month kicked off the first week of Training. Camping at a water hole overlooking the rolling hills covered in indigenous fynbos must have been an experience for anybody with a love for nature. The campers were reminded of the force of nature when a huge wind storm blew the tents down on late Sunday afternoon and were they forced to seek shelter from the elements. Replacing all damaged equipment on Monday morning, they returned to the field to resume their field work.

We started our research work at Botlierskop on Monday morning with our new set of 4x4 wheels called “THE AARDWOLF”. Two small mammal trapping grids were laid out with 25 traps each.  We focussed our efforts in two habitat types, fynbos and grassland.

After finishing our packed lunches, we set out to look for suitable places to deploy the two camera traps. Both were eventually deployed in two separate river beds where we expected game movement.
For the next three days we checked the traps every morning, for small mammals and after the first two escaped we had our skills honed and marked and weighed a total of 19 mice. We took 17 tail clippings for DNA analyses.

The afternoons were spent doing the behaviour study on the Giraffe and some interesting interactions were seen as one female is expected to be pregnant and the other female being in oestrus.
Week three was focussed the behaviour study and bird surveys and tracking at Botlierskop and Gondwana.  

The last week were put aside for tracking and the giraffe behaviour study. We tried to find the cheetah, but could not get to see them but got a good fix on their general position. We focussed on the behavioural study on Tuesday and Wednesday being our last day at Gondwana we tracked the Rhino and were hoping to see the elephant as both these pachyderms were not seen by us.  After finding them we spent the afternoon following their movements in the valley until they moved into the thicket and could not be seen anymore.

On Thursday morning we went out to Botlierskop to retrieve the camera traps and the afternoon was put aside for downloading and analysing the images. We were quite disappointed about the results, as we only recorded a waterbuck and eland on the one trap, and a giraffe on the other. I am planning to place the traps on existing game paths where there are good visibility for the next session. But that is what research is all about: not always a success. To be continued...