White Sharks – Biology, Behaviour and Physiology (part I)

This post follows on from my review of Global Perspectives on the Biology and Life History of the White Shark. That book (a collection of scientific papers) is divided into three sections, and I’m going to highlight papers that I found particularly interesting in each of the sections. My notes here are mostly nuggets of information that grabbed me when I read the papers, and in some cases aren’t even related to the author’s main point. If the paper sounds interesting to you, I suggest you track it down to read in full. Hopefully these bits and pieces are interesting, too!

In this section there were quite a few papers that interested me, so I’ll be doing three separate posts about them. Here’s the first one:

What we can learn from keeping white sharks in captivity

Captive Feeding and Growth of Young-of-the-Year White Sharks, Carcharodon carcharias, at the Monterey Bay Aquarium – Ezcurra, Lowe, Mollet, Ferry & O’Sullivan

The Monterey Bay Aquarium has successfully exhibited five juvenile white sharks between 2004 and 2009 (and possibly more, subsequently). “Young of the year” means that the sharks were born in the past year. Captivity periods ranged from 11 days to 198 days, and the sharks were released after their captivity. The aquarium is situated near an area where fishermen frequently bring in small white sharks, and which is surmised to be a pupping ground for these creatures. These sharks weighed 25-27 kilograms on capture, and were 137-164 centimetres long. The sharks were offered food daily. Initially (they shared the exhibit with other sharks, tuna and dorado) they struggled to compete for food, but after a month were the most aggressive fish in the tank and actively chased the other fish away from their rations. The estimated annual growth rate for white sharks in captivity was estimated to be about 65 centimetres per year, but there is reason to believe that this is about twice as fast as they grow in the wild, where they have to expend more energy looking for food, can swim faster and for longer distances, and have to evade larger predators, which also consumes energy.

 

Lecture: Baited Remote Underwater Video Stations (BRUVS) in False Bay

One of the projects currently sponsored by the Save Our Seas Foundation is Baited Remote Underwater Video Stations (BRUVS) in False Bay. The project involves deploying cheap video cameras in underwater housings mounted on specially constructed tripods, with a bait container filled with 800g-1kg of sardines nearby. The camera and bait are positioned so that anything that comes to investigate the bait is captured on camera. If two cameras are used to get a stereo image, the dimensions of the fish and other marine life can be calculated. The camera films for one hour, and then is retrieved back onto the boat and deployed elsewhere.

The idea for these cameras and the initial development work took place at the Australian Institute of Marine Science, where BRUVS have been used for biodiversity surveys on the Great Barrier Reef, and have several advantages over the traditional methods used for surveying marine life. Transects swum by scuba divers are limited by diving safety margins, weather conditions, availability of divers, and the fish identification skills of the divers involved. Moreover, the bubbles released by the exhalations of the divers attracts some species and repels others. Controlled angling surveys – partnerships between specially trained fishermen and scientists – can harm species that are fished out from the deep ocean (their swim bladders expand as they are pulled up through the water column, and this necessitates treatment on the surface if the fish is to survive), are not suitable for large creatures, and can be destructive.

Tony and I attended a talk at the Save Our Seas Shark Centre in Kalk Bay by Lauren de Vos of the University of Cape Town, one of the researchers on the project. She explained that the relative cost-effectiveness of the BRUVS makes them an ideal monitoring tool for South Africa’s marine protected areas. The weight of the rig is such that it is easy to retrieve and deploy, and the cost is well within the budgetary constraints faced by the managers of our MPAs.

The data collected is visual, accessible, and can be subjected to rigorous analysis to obtain relative abundance measures for all the creatures that appear on film. It can also be archived, and sent around the world. It is also very useful for educating the public about marine conservation, and “brings our MPAs to shore” in a very real sense.

The BRUVS are being piloted in False Bay, which is an important region for several reasons. There is great diversity of habitat (several kinds of reef, covering 17% of the bay, sand, etc.), it is on the doorstep of a growing urban community, and has a long history of both consumptive and non-consumptive human activity. We know that our bay has incredible diversity of species, but it is important to monitor whether the MPAs are working, and to keep an eye on areas that are vulnerable and potentially over-exploited.

Lauren showed us some of the footage collected so far, and it was wonderful to see shysharks and catsharks nosing at the bait cannister, an octopus sailing in to take a look, sevengill cowsharks rubbing themselves against the camera housing, and a spearnose skate headbutting the rig. I hope that this tool can be well-used by those managing our marine protected areas!

There is another article about the project here with some photos of the rigs underwater. There are some videos on the project here. I recommend “Foiled by an Octopus”!

Bookshelf: Dolphin Confidential

Dolphin Confidential – Maddalena Bearzi

Dolphin Confidential
Dolphin Confidential

This is a deceptively light, quick read by marine mammal researcher and conservationist Maddalena Bearzi. There is much to be gleaned from this book, and the whimsical line drawings here and there belie its strong conservation message and the scientific knowledge of dolphin behaviour that is imparted to the reader through accounts of observing dolphins in the wild. Interwoven with her fascinating life story, involving travel to all corners of the globe to study reptiles, sea turtles, and dolphins, is a fair amount of information about cetacean behaviour and life cycles. She is the co-founder (with her husband) and President of the Ocean Conservation Society, which undertakes various research projects using their fabulous (donated!) research vessel and a staff of volunteers and scientists.

Bearzi describes the activity of gathering data on cetacean behaviour while at sea, describing the excitement and wonder of observing dolphins at play and on the move, as well as the frustrations – not finding the dolphins, inclement weather conditions, differing personalities on the boat, seasickness, and the minutiae of life as a researcher in the field. She also points out how difficult it can be to interpret behaviour – dolphins lack limbs to reach for and manipulate items, and their immobile faces (while they may appear to be smiley all the time) do not show facial expressions. This sometimes makes it tricky to decide exactly what a specific behaviour means. While marine research may appear to chiefly involve lounging about on a boat, there are many hours spent translating observational data into quantitative data and drawing conclusions about what the behaviours mean. Bearzi and her team also take samples, for example of fish scales suspended in the water after dolphins have been feeding. This assists them in identifying the exact components of the dolphin diet.

Much of Bearzi’s work has been with the “metropolitan” dolphins of Los Angeles’ coastal waters. She observes first hand the impact of pollution, plastic waste, and human activities on the dolphins as well as on the other marine life around the city. Her strong belief in ocean conservation has led her to run programs in underprivileged school districts, educating children about the need to protect the ocean. She says that while these programs were a roaring success with the children, school administrators lacked the will to keep extra-curricular activities going, and eventually their efforts to run the program hit a brick wall.

Unsurprisingly, Bearzi is strongly opposed to keeping dolphins in captivity, and does not think that swimming with dolphins is a good idea either. (From what I’ve seen of it, I am inclined to agree with her!) She speaks from a position of strong respect for the creatures she studies and for the spaces they inhabit, and the idea of actually grabbing onto one of them for a photo opportunity would be repugnant to her.

You can buy the book here if you’re in South Africa, otherwise here or here. For a kindle copy, go here. It’s an enjoyable read with a strong narrative thread. For a young person, particularly a girl, considering a career as a field biologist, it’s also an excellent read.

A Tour of RV Mellville

RV Melville at anchor at the V&A Waterfront
RV Melville at anchor at the V&A Waterfront

Being an active volunteer at the Two Oceans Aquarium has its perks, and one of them was an invitation to a guided tour of the Scripps Institute of Oceanography (SIO) vessel, RV Melville, while it was berthed at the V&A Waterfront at the end of March. The RV Melville is a research ship that sails the world loaded with scientists and crew engaged in various research projects.

Our tour was conducted by Captain Dave Murline, and First Mate Ian Lawrence. The position of captain rotates every few months, as does the entire crew of the ship. The SIO is based in La Jolla, California, and has a long and distinguished history of boat- and laboratory-based ocean research. It is part of the University of California, San Diego. The First Mate assured me that I was allowed to take photographs on the tour, and said that there is nothing secret or classified about the ship. While I was slightly disappointed by this – always hoping for intrigue – I am happy to be able to share photos with you!

The front of the ship showing the crane used to retrieve dredges from the ocean floor
The front of the ship showing the crane used to retrieve dredges from the ocean floor

The ship has a propulsion system that allows it to move sideways, and to hold a position with incredible precision even in rough conditions. This is important when taking readings or retrieving scientific gear from a particular location. Engine power is converted to electricity, which runs everything on the ship. A massive winch, seated low in the vessel for stability (it is very heavy) is used for retrieving samples and instruments from the sea floor.

All along each side of the ship are life rafts – enough on each side for the entire ship’s complement. Thus, if the ship heeled over to one side, everyone would be able to escape in a life raft. So simple and obvious, but not to the builders of the Titanic. Thank goodness for lessons learned.

A 26-person life raft bursts out of this barrel when it gets wet (or is opened)
A 26-person life raft bursts out of this barrel when it gets wet (or is opened)

The ship had just completed a voyage of several months along the Walvis Ridge, as Chief Scientist Dr Anthony Koppers explained. Dr Koppers showed us examples of the rocks that the scientists on board (the majority of whom are actually undergraduate and graduate students) harvested from the seamounts along the Walvis Ridge, as well as some deep sea coral skeletons. He explained how deep sea corals do not grow as abundantly as the coral we’re accustomed to see in shallow, tropical oceans, but occurs widely spaced on the dim, cool seafloors where it occurs.

Since the RV Melville’s primary purpose is scientific research, Dr Koppers was quite an important person on board and the scientific agenda of the cruise was paramount. At times groups were working around the clock dredging up samples of rock and sediment.

View from a porthole in the library
View from a porthole in the library

There are exercise bikes, rowing machines and weights scattered about the ship, in hallways and stairwells – apparently this is a good way to pass the time and discharge excess energy at sea. A well-equipped library (I even spotted a Deon Meyer book), a crew lounge with a television and dvds, internet terminals and – by all accounts – wonderful meals three times a day, ensure that the leisure time of the crew and scientists on board is well spent even though it’s in a fairly cramped space.

The RV Melville is not a new ship, but I was impressed by what an excellent condition of neatness and cleanliness prevails throughout the vessel. Clearly the crew take great pride in their work.

Plaque commemorating the builders of the RV Melville
Plaque commemorating the builders of the RV Melville

Bookshelf: Atlas of Oceans

Atlas of Oceans – John Farndon

Atlas of Oceans
Atlas of Oceans

I confess that I was not totally enamoured of this book when I started reading it. It seemed overly simplistic, but by the time I finished it I realised that its author had neatly summarised both the wonder and variety of the world’s oceans, and the threats facing them from human activity.

Boasting a foreword by Carl Safina, whose most well-known book is Song for the Blue Ocean, the book is written by John Farndon, a prolific children’s author, and published by Yale University Press. Farndon is British, as is evidenced by his assertion, during a discussion of the warming effect that the Gulf Stream current has on the north Atlantic ocean, that Great Britain has a very pleasant climate. No one else – except perhaps an Inuit – would make such a claim.

Farndon’s credentials as a science writer for children make this volume a pleasure to read – he deals with wide ranging and fairly complex topics, but in a completely understandable way. The book is well illustrated with photographs (some – such as ones of a row of narwhal and a calving ice shelf, of dubious quality), diagrams and maps. The sections each cover two facing pages, so it’s quick to dip into and finish reading a section before bed (for example)!

Special sections focusing on particular habitats (such as coral reefs or the ice), wildlife (I was particularly charmed by the highly endangered vaquita) and issues (mainly related to conservation) are spread throughout the book. Farndon lays the groundwork for a basic understanding of our oceans by covering concepts such as ocean tides, currents and physical oceanography, and then moves on to specific sections on each of the world’s oceans. He also writes about the major seas, such as the ones in Europe and the South China Sea.

This isn’t a long or complex book – it’s under 250 pages long – but comes with a glossary, a list of endangered species (including their status of endangerment and scientific name), suggestions for further reading, and contact details for a long list of ocean conservation organisations. It’s the kind of book that I will dip into frequently – there are some useful photographs (one of the marks left on the seabed by bottom trawling fishing boats springs to mind) and maps (I liked the one showing the whole 2% of the world’s oceans that are in marine protected areas – MPAs) and excellent coverage of the overfishing problem facing us today. Also dealt with are oil spills, whaling, global warming, coral reef and ice shelf destruction due to warming of the oceans, dead zones that result from fertiliser runoff into the sea, and anything else you can think of that impacts the health of our oceans.

An edited extract from the book can be found here, along with a magnificent photo of a basking shark. I recommend it, and it’s suitable and accessible for anyone from a precocious ten year old and up. It’s the sort of book you could give to someone who doesn’t know much about or care particularly for ocean matters, and it would bring them right up to date (and probably make them care).

You can buy the book here if you are in South Africa, and here if you’re not.

Lecture: George Branch on evolution

The fourth in the Save Our Seas Shark Centre in Kalk Bay’s series of talks was presented by George Branch, who (in my eyes at least) has achieved near-legendary status as a marine biologist and author. He is one of the authors of Two Oceans, the invaluable reference guide to South African sea life, and also wrote the classic reference The Living Shores of Southern Africa in the 1980’s with his wife Margo. The topic of his talk was The Myths and Magic of Evolution, a subject that interests me enormously but until a couple of years ago it was not part of my education (formal or self-taught) at all. Unfortunately, at this stage in my life, I am so ignorant on the subject that I simply cannot judge where to start learning about it.

Enter the Save Our Seas Shark Centre! Prof Branch turned out to be a wise, patient (I asked several stupid questions) and fascinating teacher – clearly he is not only passionate about his areas of specialisation, but also about communicating the subject matter to others, at both beginner and expert level. Several times in his talk he indicated that he’d changed his mind and learned new things in the past two years – which impressed me enormously. I spent a good part of my young adulthood in the presence of frighteningly dogmatic individuals, to whom an idea such as the one espoused by John Maynard Keynes when he said, “When the facts change, I change my mind – what do you do, sir?” would be anathema. Fortunately Prof Branch is not dogmatic – he is gracious, curious, and thorough.

The subject of evolution is controversial in some circles, and Prof Branch started his talk by stating that no science is any use (in fact, I wouldn’t even call it science) if you can’t test the ideas. An untestable hypothesis is doomed to remain just that – a hypothesis, or a belief. Beliefs are only good for and useful to their holder. The talk was divided into five sections –

  1. The basics of evolution
  2. Tests of evolutionary theory
  3. New advances
  4. Controversy
  5. Guidelines

We found the basics of evolution, as set out by Charles Darwin helpful:

  • more individuals are born than survive to reproduce (this is obvious – I am one of those individuals)
  • variety exists among individuals of a species (also obvious – compare my freckles to Tony’s easily-tanned skin)
  • fitter individuals are more likely to reproduce (“survival of the fittest” – a runty little shark who can’t swim fast isn’t going to find himself a sharky girlfriend – and the definition of “fitter” will vary among species)
  • if characteristics are inherited, species slowly evolve, through either adaptation/microevolution (small changes), or speciation/macroevolution (splitting off into a new species)

The first two points listed above were obvious in Darwin’s time. According to Prof Branch, today we have evidence of all four processes.

It annoys and frustrates me that a discussion of science must mention religion, but unfortunately a lot of the objections to evolutionary studies have come from the religious right. One of the common difficulties is reconciling a seemingly random process (evolution) with the idea of a creator characterised by order. With this in mind, Prof Branch (who has spiritual convictions of his own and is apparently occasionally challenged about evolution at church by those less well versed in the sciences) pointed out that evolution is not a random process. The mutations that add variety to populations are random, but the selection process is not random.

The second part of the “basics” was an explanation of sexual selection, also observed by Darwin. To summarise it as far as one safely can, sexual selection occurs as one gender (I think usually the female of the species!) “likes” something in the other gender, that characteristic will be favoured (i.e. lead to more reproductive opportunities in those carrying it) EVEN if it’s a DARN NUISANCE. Just think about birds of paradise, or peacocks as an example.

There are as many as fourteen different tests or lines of evidence one can follow to test whether the predictions made by evolutionary theory are correct. Some of these are survival rates (clearly not every creature that has ever lived has survived to reproduce – if they had, the universe would be completely filled with bacteria, the population of which would be expanding outwards at the speed of light), and the evidence of the fossil record (increasing complexity diversity, and size in newer fossils, and also the existence of intermediate forms). Another line of evidence for evolution is the vestigial organs that occur in many creatures, such as the eye remnants in blind cave fish, the pelvis and femur remnants that exist in dolphins, and remnants in some microbes of the ability to photosynthesise. One can also observe “evolution in action”: speciation in plants, fast evolution of diseases such as flu and HIV, and many other examples.

I’m not going to go into the recent discoveries that Prof Branch covered, but suffice it to say there is enough material for several conferences. He also passed quickly over several new ideas that are being studied – we were running out of time!

In closing, Prof Branch discussed what many perceive as the conflicting forces of religion and science. Science provides us with facts, and through testing of ideas and experiments, it tells us what is true. Religion tells us how to employ those facts in our lives. The example of the different spheres of influence held by science and religion that he gave was of the atomic bomb – a stunning use of science, but a wholesale failure of ethics.

Two of the myths about evolution that Prof Branch dispelled at the end of his talk were particularly interesting to me. First, evolution cannot explain the origin of life. It can explain how life developed and increased in complexity, but not how it started. Second (I knew this already but it’s a stupid and oft-repeated objection to evolution by people who are too intellectually lazy to come up with anything more cogent) evolution is not “just a theory”. I encourage you to look up theory in the dictionary. When scientists talk about the “theory of relativity”, “theory of gravity”, “atomic theory” and “theory of evolution”, they are meaning it in the first sense.

In closing, I’ll list the guidelines Prof Branch gave us for handling the subject:

  • Respect the views of others
  • Recognise the different goals and limits of science and religion – they can be complementary
  • Be frank about ignorance, both personal and scientific
  • Insist on the testability of ideas and opposing ideas

I’ll leave you with a quote from Billy Graham that Prof Branch used towards the end of his talk:

I don’t think that there’s any conflict at all between science today and the Scriptures. I think that we have misinterpreted the Scriptures many times and we’ve tried to make the Scriptures say things they weren’t meant to say, I think that we have made a mistake by thinking the Bible is a scientific book. The Bible is not a book of science. The Bible is a book of Redemption, and of course I accept the Creation story. I believe that God did create the universe. I believe that God created man, and whether it came by an evolutionary process and at a certain point He took this person or being and made him a living soul or not, does not change the fact that God did create man. … whichever way God did it makes no difference as to what man is and man’s relationship to God.

Billy Graham: Personal Thoughts of a Public Man, 1997. p. 72-74

I am sorry that religious discourse has to intrude on a discussion of science. Many of those objecting to the theory of evolution on the basis of their personal beliefs are unfamiliar with the scientific method, the peer review process, and the language of science. Hopefully if, like me, your ability to comprehend this material was (or is) impaired by religious dogma and pseudo-science, you will be able to read the mainstream scientific literature that discusses the subject and gain more factual information in order to make an informed judgment on the topic.

For further reading, you can try Darwin’s Origin of Species (may be a bit dense – I haven’t read it), The Greatest Show on Earth by Richard Dawkins (be warned, he is an angry little man, but a good scientist), Guns, Germs and Steel by Jared Diamond (one of my most favourite books and authors), or The Structure of Evolutionary Theory by Stephen Jay Gould. Gould and Dawkins have both written a lot on the subject and may be a good place to start.

[Given my relative ignorance on this subject, if anything I’ve said here is inaccurate, you can be sure it was an error of transcription or comprehension on my part, and not an error of fact by Prof Branch!]