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Blue Shark

Blue Shark

An account of photographing blue sharks off Cornwall, Southwest Britain, a few years back, and a link to buying blue shark fine art prints of these amazing hunters of of the oceans at

On a clear July morning I stumbled out of my bunk (I was living on a boat at the time) at 5.30am, forced out my the insistent buzzing of my phone alarm. One hour, and one strong coffee later, I squeezed my dive bag into the back of Ritchie’s car and we were off. We had over a hundred miles to cover, and a boat to catch.

Blue shark swimming through clear blue water. Cornwall. © Colin Munro Images
A Blue shark, Prionace glauca, swims leisurely through clear blue water off Cornwall, UK.

Charles Hood runs the best, and most successful, blue shark snorkelling operation in the UK. His boat, a large rigid-hulled inflatable (RIB) operates out of Penzance, almost at southwesternmost extremity of the British mainland, so that’s where we were headed. The boat is a fast open boat, perfect for getting us 10 miles offshore quickly, but small and devoid of any shelter from the elements. So we changed in to wetsuits on the quayside, packed our camera gear in dry bags carefully padded with towels and sweatshirts for the bouncy ride out, and we were off.

Blue shark fine art prints. buy fine art prints of a blue shark. Colin Munro Photography
Blue shark, Prionace glauca. A female blue shark swimming close to the surface off Southwest Cornwall, UK. Blue sharks are easily recognisable by their slender form, long pectoral fins and vivid blue colour. Like many shark species they are counter-coloured, blue on their backs and white below. Blue sharks are found off Southwest Britain between July and October. For reasons that are still not fully understood it is most females that are seen in British waters. Female blue sharks can be recognised by the absence of of claspers on their belly; sexually mature female blues will often have prominent scars of their head, neck and back. These are mating scars causing by bites from the male blue shark during mating. Blue sharks are found in all major oceans, in temperate and tropical waters.

Each year blue sharks arrive off the coast of Southwest Britain, normally sometime in mid-June and remaining until mid-October. Blues are true oceanic sharks; they inhabit deep water, only infrequently venturing on to shallower, continental shelf waters. They are found in tropical and temperate oceans around the globe. However, in the tropics they tend to stay in deeper, cooler water but are often observed in surface waters in temperate seas. They feed on fast moving prey such as squid and schooling fish. Much of their feeding appears to be done in deeper waters. We know this partly from studies looking at gut contents, identifying the hard tissue remains of the prey species, and knowing where those prey species live, and partly from small data loggers, recording depth profiles, that are attached to sharks and then recovered at a later date. Below 100 metres, it seems they predate mostly on squid, in particular those belonging to the Histioteuthidae family, more commonly known as cock-eyed squid. Cock-eyed squid are bizzare creatures that inhabit the twilight zone of the oceans, so-called because their left eye is around twice the size of their right. Observations with deep water remotely operated vehichles (ROVs) have shown that they swim with the left eye facing upwards, and the right facing down. It’s believe the the huge left eye is used to pick up the faint sunlight coming from far above; the smaller right eye, staring into the depths, serves a quite different purpose. It picks up bioluminecent glows and flashes from prey (or predators below). But blue sharks are not fussy eaters. Studies off the coast of Brazil have found they eat large numbers of oilfish (a deepwater member of the mackerel family) but will also sometimes grab seabirds such as shearwaters. Those off Southern Brazil were found to be mostly scavenging on dead baleen whales. But I have digressed somewhat from our trip. Some ten nautical miles out Charles stopped the RIB and allowed us to drift. Sure we were a fair way from shore, and in pretty deep water, but still well within continental shelf depths, probably 50-70 metres, as we drifted. The 100 depth contour was still over 20 miles distant. So what tempted the blues, normally oceanic species, this close inshore? As we drifted Charles began to prepare the chum bag that hopefully would draw nearby sharks to our boat. A small hessian sack was filled with chunks of mackerel and mackerel guts, including some caught angling off the stern of his RIB. Tied just off the side of the RIB, a slick of fish oil drifted away down current. This is the clue to why blue sharks arrive in coastal waters of southern and western Britain. Mackerel also arrive around British coasts during the summer months, often found in huge shoals numbering thousands of fish. Like their deeper water relatives, the oilfish, mackerel are an oily fish, so a high energy food source for any predator fast enough to catch them. And the blue shark is just that; generally a sedate swimmer it can move with lighting bursts of speed.

Once our bag of chum was positioned, and final checks on cameras completed, all we then had to do was wait. Charles dug out his fishing rod and started supplementing our chum supply with a few extra mackerel. And we waited. There was no wind, and just a slight, rolling swell on the sea. The sun was hot and the sky a clear blue, so it was not extactly a hardship. The sun climbed to its zenith, then slowly fell westward as morning gave way to afternoon. We were woken from our torpor when, around 2pm, a group of three sunfish drifted close. Sunfish are odd-looking disc shaped fish. They feed on There was a flurry of activity as we grabbed cameras and donned fins, but they were skittish and disappeared in seconds. We settled back in to watching and waiting. At around 3.30pm Charles announced that we should start heading back to shore at 4pm. The minutes ticked by; 4pm arrived and still no blues. Charles apologised but, as we were well aware, there is never any guarantee with wildlife. He announced we would give it another 20 minutes. At 4.15 the first blue arrived. Rather than leap in immediately, we gave it time to settle and get used to the boat. A couple of minutes later a second arrived. Charles had been very clear on the safety aspect, wearing gloves, no shiny jewellery. The necessity for this was made abundantly clear when one of the sharks managed to grab to chum bag. Its razor sharp teeth ripped through it like paper, and bits of mackerel guts spilled out into the water. The bag was quickly quisked out of the sea and we gave it a minute for the cloud to disperse. Once Charles was confident the sharks were no longer likely to disappear immediatly, we, one by one, slowly slide over the side of the boat and in to the water.

Richie fires off a couple of snaps as a blue passes beneath him.

Once in the water I dipped my head to check all around me, then slowing finned away from the RIB. Once around 8 metres away I stoppped finning, and started checking around. I could clearly see my three companions at this stage, floating 5-10 metres away from me. Every so often a shark would cruise in, swimming below or between us, to to check out us or the RIB. The water was clear, visibility a good 15-20 metres, but the sun was now low in the sky. When the sun is overhead, and light hits the waters’ surface more or less perpendicular, then much of that light penetrates the surface; but late afternoon, when the sun is low and its rays hit the water at a shallow angle then most of that light bounces off the surface and it becomes markedly darker just below than above. My photographic problems were two-fold. The reduced light levels made focussing a little trickier, and when a blue shark came fast out of the expanse of blue water, the camera would struggle to pick up contrast and focus quickly. I fiddled with the settings, pre-focussed using my colleagues as targets, fired off test shots and again readjusted my settings. All the time keeping looking around me. A RIB, with its large surface area above the water, will drift with wind and tide, but a swimmer, around 90% below the water’s surface, will drift with the tide alone. So as I floated I was aware that the distance between was growing. This was not a concern; conditions were perfect and I knew Charles would be fully aware of our positions. On the contrary, it gave me space around me. As I drifted I also became aware that one of the sharks had become interested in me, and was moving with me, not steadily but zig-zagging. It would pass close, then swim off , to turn and pass close again.

A blue shark checks me out during our dive off Cornwall. © Colin Munro Images
A curious blue checks me out; maybe checking its reflection in my camera dome port?

This was not in a threatening or aggressive manner, but rather one of curiosity. A couple of times it would swim straight towards me, only to stop maybe 18 inches in front of me. Whether it was seeing reflections in the large glass dome port of my camera housing I am not sure. Whatever the reason it provided me with more perfect photo oportunities than I could have hoped for. Thirty minutes passed in what seemed like three, and Charles was recalling us to the RIB. We may have had to wait, but performace at the end far exceeded our expectations.

Fine Art Prints

I have made two of my images from this trip available as fine art prints and wall art. These are available to be purchased in a wide range of media and sizes directly from my Colin Munro Images website. Media available include traditional giclée prints, stretched and flat mounted canvas, metal prints (dye directly infused on sheet aluminium) and acrylic, from 8 inches up to 48 inches across. My prints are produced by Bay Photo Labs in Santa Cruz, California. I choose bay Photo Labs for the excellence of their quality, with over 40 years providing printing services to professional photographers, their constant innovation, combining the latest technology and innovation with the finest traditional techniques, and their committment to the highest environmental standards using green technology. You can buy my prints directly here at

How can I buy fine art photographs if I am not in North America?

I also use excellent printers in the UK, and Bangkok, Thailand. If you are in Europe or Asia, please email me with the photo code, the print style and the size, and I will arrange for it to be delivered from either UK or Bangkok. If you are elsewhere in the World, and would really like to buy one of my images as a fine art print, drop me an email and we’ll see what I can work out. (My site showcases my fine art photographic prints printed in the UK. You can also buy prints directly).

I am slowly moving my marine biology orientated blogs to my other blog site: I may eventually remove them from this site. This article can now be found here.

The basking shark

Large basking shark feeding

Large basking shark feeding

Large basking shark feeding

I clearly remember my first in-water encounter with a basking shark.  Quite a few years ago now, I had gone out specifically to try and video a basker underwater.  After a couple of hours we spotted a pair slowly circling a ball of plankton.  I slipped mask, fins and snorkel on and slid in to the water.  Basking sharks can be sometimes be wary and dive when one gets close, but these two seemed quite unconcerned by my presence.  I floated on the edge of the plankton ball and watched them circling.  As one approached out of the gloom I started to swim towards it.  Even through you know it’s quite harmless it is still a strange feeling watching a six metre long shark swimming straight towards you with its mouth wide open.  A mouth I could easily fit inside.  At the last moment the shark would alter course slightly and cruise past me.  The experience was similar to standing too close to the edge of the platform watching a train go past.  Again and again the sharks would circle and cruise past, sweeping by less than a metre from me.  Just me and two large sharks.  It was a mesmerising experience, but I could not help thinking ‘this is so easy!’ Little did I realise at the time quite how lucky my encounter was.  Several years and quite a few attempts would pass before I was able to repeat the experience.

The basking shark, Cetorhinus maximus, is the second largest fish in the World. Mature adults commonly reach between six and and seven metres in length, occasionally reaching around nine metres. Despite their massive size basking sharks are quite harmless. They are gentle filter feeders. During summer in the north-east Atlantic they can often be seen swimming close to the surface with their mouths gaping wide. A baskers’ gape can be over a metre top to bottom, so that’s pretty wide. As they swim forwards water is forced in to their mouths, passing across their gills where oxygen is extracted, and out through their large gill slits. This water flow serves a dual purpose. The arches between the gill slits are covered in long stiff bristles called gill rakers. These gill rakers sieve the water flow, retaining planktonic organisms. This is the food of basking sharks. In northern Atlantic waters they feed especially on copepods (planktonic crustaceans) particularly those of the genus Calanus, which occur in enormous numbers in the North Atlantic. Large numbers of such tiny creatures are required to sustain something as large as a basking shark.  Therefore baskers need to filter very large volumes of water.  It has been estimated that around 1.3 million litres of water will pass through the mouth and over the gill rakers of a large basking shark every hour.

Basking shark feeding, showing large gill slits the almost encircle its head

Basking shark feeding, showing large gill slits the almost encircle its head

In the North East Atlantic basking sharks start to appear off the tip of Cornwall (SW England) in early May.  This co-incides with what local fishermen call ‘May-water’, where the coastal seas turn green and turbid due to the seasonal population explosion of plankton.  Throughout the summer months sharks will move northwards through the Irish Sea and around the west coast of Ireland.  In the years immediately following WWII the author Gavin Maxwell ran a basking shark fishery from the island of Soay in the Inner Hebrides, exploiting this northward seasonal migration. The operation was beset with problems and drove him to the edge of bankruptcy.  Basking sharks were hunted by Norwegian and Irish boats also. Due to concern over dwindling numbers, the basking shark received full legal protection in  U.K. waters in 1998.  The last British shark fisherman, a larger than life character called Howard McCrindle, ceased operations a year earlier.  The basking shark is now protected throughout E.U. waters. In 2006 hunting also ended in Norwegian waters.

A basking shark swimming through plankton rich waters off Southwest England

A basking shark swimming through plankton rich waters off Southwest England

Despite their large size, relatively slow movement and surface feeding habits there is much that remains unknown about the life history of basking sharks. Each year the they appear in late spring, then disappear again at the end of September.  Where they go and how they live for the rest of the year has been a mystery, and remains so today, though we are starting to get tantalising clues as to the the answer.  Occasionally, basking sharks would be caught in trawl nets during the winter months.  Some of these were found to have shed their gill rakers, suggesting they were not feeding.  This lead to the theory that they became dormant in winter, hibernating on the seabed.  This theory had a certain plausibility to it.  Basking sharks have enormous oil-filled livers.  The liver can be 25% of the sharks body mass (the low density oil gives the shark buoyancy, allowing it to swim efficiently at the surface; it was also this high quality oil for which they were hunted). It was suggested that this enormous store of liver oil could sustain the shark for months without feeding. Recent research using data logging tags has begun to shed light on shark behaviour during the winter months.  The tags used detach after a predetermined time and float to the surface, where they transmit the data data to satellites. The data at the time of writing indicates that basking sharks are active all year round, but spent much of their time at considerable depth, 200 and 1,000 metres.  It also seems they are highly migratory.  One 5 metre female nicknamed ‘Banba’, was tagged off Malin Head, the most northerly point of Ireland, in the summer of 2012.  On the 13th December 2012 the tag popped off and was located by satellite – just west of the Cape Verde islands 5000km to the south.  The still sparse, but growing, body of evidence now suggests that – in the North East Atlantic move in to coastal waters from deep water in April or May.  As the water warms and daylight lengthens (and so plankton blooms) there is an erratic movement northwards.  At the end of the summer they return to deeper water, heading west away from the British isles and mail and Europe, and some probably heading south also.  So in reality we should maybe consider the basking shark as a deep water species that happens to congregate in shallow water during the summer months in pursuit of rich feeding.

As a final aside it is often written that basking sharks are toothless filter feeders. Basking sharks are filter feeders utilising gill rakers in a similar fashion to the baleen plates of great whales to trap small planktonic creatures but surprisingly they also teeth.  In fact they have hundreds of tiny, backward-pointing teeth.  What, if any, purpose these teeth serve is not known.  They may be a vestige from a more predatory ancestry; equally there may be more still to learn of the basking sharks feeding habits.

You can see more of my shark images here

Blue sharks, graceful sea wolves

Blue shark, Prionace glauca. A female blue shark swimming close to the surface off Southwest Cornwall, UK.

The blue shark, Prionace glauca, is possibly the most beautiful of sharks.  It is a slender, fast and graceful shark, but it is the vivid, almost electric blue colouration that is most striking.

Blue shark, Prionace glauca. A female blue shark swimming close to the surface off Southwest Cornwall, UK.

A blue shark passes close by.

Blues are oceanic sharks, uncommon in shallow coastal waters.  In the tropics they are normally found in deeper, cooler waters, but in temperate seas they are more likely to be found in surface waters (thus are described as being epipelagic).  This does not mean that in temperate waters they occur only in the warmer surface layers.  Recent data from satellite tags have shown that they blues may regularly undertake dives to more than 1000 metres.  One male blue shark, nicknamed Bodi by the researchers, was logged as having dived to 1250 metres off the Bay of Plenty (New Zealand) three weeks after being tagged in 2013.  An earlier joint British- Portuguese study recorded a female blue shark diving to 1160 metres off the coast of Portugal (Queiroz et al, 2012).   This behaviour is probably linked to hunting activity.  Blue sharks are quite catholic in their diet, eating a wide range of mid-water fish and cephalopods,  but appear to be particularly fond of squid, and of course squid will often undertake marked vertical migrations, with many species occurring at considerable depth.  That this deep diving behaviour of blues is primarily foraging for food is supported by a preponderance of deep water quid species found in the gut of contents of blue sharks caught by long-lines, in particular the wonderfully named vampire squid, Vampyroteuthis infernalis, a small deep-water squid those scientific name literally translates as the vampire squid from hell.

In the northern Atlantic at least, they appear to undertake seasonal migrations. They are unusual amongst ocean sharks in that they will sometimes aggregate in groups, often all same sex, as they roam.  This pack-like activity has lead to them being dubbed the wolves of the sea.  Around Southwest Britain blue sharks start to appear in June each year, and hang around until late October or early November.  Although there have been attacks on humans by blue sharks, aggressive behaviour is relatively rare.  Certainly in British waters, where large blues are rarely seen, most are quite timid and easy to scare off accidentally.  The largest blue caught in UK waters was approximately 2.5 metres long and weighed 107kg. This was caught off Penzance, Cornwall, in 2012 (but was also released).  Blues can grow up to 3.5 metres or more (the largest on record was 3.83 metres long) the females being significantly larger than males.

Blue shark, Prionace glauca. A female blue shark swimming close to the surface off Southwest Cornwall, UK.

Blue shark, Prionace glauca. A female blue shark swimming close to the surface off Southwest Cornwall, UK.

An underwater encounter with a blue shark is a wonderful experience, and provided one takes sensible precautions (i.e. wearing gloves, not wearing shiny bits of equipment and NOT trying to feed them) is normally quite safe.  Blue sharks have been one the shark species hardest hit by the practice of shark fining in various parts of the World and there numbers appear to have declined markedly.  Consequently it’s worth remembering that most blue sharks have far more cause to fear us that vice versa.

The above, and more of my blue shark images, can be found on my stock image website They can be licensed for publication, or purchased as fine art prints and canvas wall art.

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References cited: Queiroz N, Humphries NE, Noble LR, Santos AM, Sims DW (2012) Spatial Dynamics and Expanded Vertical Niche of Blue Sharks in Oceanographic Fronts Reveal Habitat Targets for Conservation. PLoS ONE 7(2): e32374. doi:10.1371/journal.pone.0032374


Photographing Blue sharks off Cornwall

Blue shark, Prionace glauca. A female blue shark swimming close to the surface off Southwest Cornwall, UK.

A few days ago I was fortunate enough to get in to the water off Cornwall with a couple of blue sharks (Prionace glauca).  Getting some good images of blues had been high on my ‘to do’ list for several years, but for one reason or another it had not happened. In part this was a result of the dreadful summers we have had in the UK for the past few years; wet and windy and severely limiting the number of days when it was possible to spend all day offshore in a small boat (and limiting even more the number of days one would want to). This summer has so far been perfect, high temperates and light winds.

Blue shark, Prionace glauca.  A female blue shark swimming close to the surface off Southwest Cornwall, UK.

Blue sharks are highly migratory, with strong evidence for there being a single well-mixed population within the Atlantic Ocean and seasonal trans-Atlantic migration.  Some studies indicate a crosswise annual migration across the temperate zone of the Atlantic but evidence for this is inconclusive.  What we do know is that blue sharks start to appear off the tip of Cornwall in early July and remain around Southwest England until late September.

Blue shark, Prionace glauca.  A female blue shark swimming close to the surface off Southwest Cornwall, UK.

Off the tip of Cornwall is one of the best areas to see blues; it also has the advantage of exceptionally clear water.  Most are found at least five miles offshore, so with the longish drive an early start was required.  By 10a.m. we were drifting with the current, a nice fish oil slick trailing from our chum bag, cameras ready and waiting.  The sky was blue, the sun hot, the sea ruffled by a light breeze and our spirits were high.  And we waited.  Mid-afternoon a brief flurry of excitement: two sharks arrived within the space of an hour, grabbed our mackerel bait….. and disappeared.  By 4.30pm our hopes were fading and our thoughts turning to when we could schedule the next trip.  Suddenly at 4.45pm a third shark arrived.  A smallish female, probably around 5ft, but most importantly she showed none of the skittishness of the previous two. She was interested in the fishy smell from our chum bag and she was hanging around.  It took a real effort of will to stay calm, remain on the boat and allow her time to settle – what if she also suddenly disappeared?  However, after a few minutes Charles, the boat skipper, gave us the nod and Richie and I slipped gently and quietly in to the water.  As we swum towards her she showed no fear at all, appearing quite curious about us, to the extent that she temporarily lost interest in the chum bag and began cicling us as we drifted slowly from the boat.  Time and again we would swing around to make close passes, to the extent that she occasionally had to be gently pushed away as she came nose to nose.  A more obliging photographic model I could not have wished for.  Around 20 minutes passed in a flash, at which point she became bored with us and disappeared.  Yet no sooner had we climbed back in to the boat than a larger female arrived.  She definately wasn’t timid; before anyone could react she had grabbed the chum bag and was tearing it to pieces.  Within seconds the water around the boat was a murky brown from the contents of the chum bag and the bag itself shredded.

This was too good an opportunity to miss, all four of us hit the water.  She was a real beauty.  Between 6 and 7 ft long, the most dazzling vivid blue on her dorsal surface with deep indigo patches near her dorsal fin, pure white on her underside.  As she passed close the mating scars left by the males teeth could be clearly seen on her head neck and back.  For more than 30 minutes she hung around. circling us.  It was almost 6pm when we finally climbed out of the water.  Tired but very happy.

passing under a snorkeller

Our trip was on board the RIB of Charles Hood (  Charles regularly runs basking shark and blue shark trips from Penzance, Cornwall.  I would heartily recommend him.

All my blue shark photographs are available for licence and some as fine art prints along with all my other stock images at Or you can contact me directly email me

Signed canvas prints and photographs of my work can be bought through my Etsy Store

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Porbeagle populations in the N.E. Atlantic critically endangered.

Porbeagle shark, Lamna nasus, caught as bycatch, on the deck of a fishing vessel, Irish Sea, UK. Colin Munro Photography

Porbeagle shark, Lamna nasus, caught as bycatch, on the deck of a fishing vessel, Irish Sea, UK. Colin Munro Photography

Porbeagle shark, Lamna nasus, caught as bycatch, on the deck of a fishing vessel, Irish Sea, UK.

Porbeagle sharks (Lamna nasus) are a temperate water species of shark belong to the mackerel shark family (Lamnidae), the same family as salmon sharks, makos and great whites. Adults are around 2.5 metres long and and weigh about 140kg. They are considered vulnerable throughout their range. The population around UK shores (NE Atlantic) is considered critically endangered (IUCN). The International Committee for Exploration of the Seas (ICES) advises that the NE Atlantic stocks may be close to collapse. A quota system for porbeagles was introduced in 2008. The Total Allowable Catch (TAC) was reduced to 436 tonnes in 2009. In UK waters a total ban on targetted fishing by commercial fishermen has been in place since 2010, with release of accidental bycatch whenever possible. ICES has called for a zero TAC since 2006; there are now proposals to bring this in to effect throughout the EU.

There is a still a problem in that porbeagles, are fast swimming predators that feed on squid and fish. Freuqently the species that fishermen are also targetting. Porbeagles may end up as accidental bycatch in trawls or in set nets. Like other mackerel sharks, porbeagles’ gills work by obligate ram ventilation. This means they need a constant flow of water past their gills in order to oxygenate their blood. Trapped in nets they quickly drown. As set nets are often deployed on the seabed then hauled 12 or 24 hours later, even if the fishermen would like to release them alive it will be too late. The Centre for Environment, Fisheries and Aquaculture Science (CEFAS) is currently conducting a DEFRA commissioned study in to the threats posed by accidental bycatch to porbeagle in UK waters. Hopefully this will result in guidance for fishermen as to the best ways to minimise the risk of accidentally catching porbeagles.

Save our Seas is working with the Marine Institute in Ireland to satellite tag porbeagles. This should help us understand portbeagle migration and possibly identify nursey areas. This has so far shown that porbeagles tagged off northern coast of Ireland have resurfaced off Lisbon, Portugal. Details of the study can be seen here.

Interesting fact: All fish are cold blooded right? Not quite. Recent studies have found that most mackerel sharks (salmon sharks, great whites, shortfin mako and porbeagles) are able to maintain their body temperature above that of the surrounding water, as marine mammals do. They acheive this by passing deoxygenated blood, heated by muscle activity and biochemical reactions, past a network of cold, oxygenated blood travelling through a network of fine arteries (the rete mirable, literally ‘wonderful net’) thus transferring heat to the arterial blood rather than simly losing it to the external environment. Salmon sharks (Lamna ditropis) sharks have been found to maintain their core temperature up to 21 degrees C above that of the surrounding water (Goldman et al, 2004)

Porbeagles are endangered throughout the Atlantic. The EU has now voted to ban commercial porbeagle fishing. Currently only Canada allows a commercial fishery, although the Canadian Government are coming under considerable pressure from conservationists within and outside Canada. More more information on this read the Friends of Hector article here.

Goldman, K.J., Anderson, S.D., Latour, R.J. and Musick, j.A., 2004. Homeothermy in adult salmon sharks, Lamna ditropis. Environmental Biology of Fishes 71 (4): 403–411.