The forgotten fish?


Shark finning is a massive, multi million dollar industry. But there’s another fish that’s more endangered (in fact, the IUCN once described this as one of the most endangered species on earth) that’s also being killed illegally for one small component of its body. Above is the beluga, or Huso huso. Not the whale, but the sturgeon. Growing up to some massive sizes of 1500 kilos and 7.2 meters long (as one specimen caught in 1827) and living for up to 100 years it is also the oldest living family of bony fish. It is hunted for its roe. Beluga caviar is one of the most exclusive and sought after types of caviar, and severe overfishing has caused this beautiful fish to be classified as critically endangered by the IUCN.

Beluga caviar can sell for as much as 10,000$ per kilo depending on the quality, with a special sort (harvested exclusively from females at least a 100 years of age) going for some 25,000$ per kilo.

Much like the shark, the beluga is an apex predator in its environment, and it would be a shame to see such a beautiful fish disappear.

My obligatory Kony2012 post.

There’s been a ridiculous amount of buzz lately about this whole Kony 2012 thing, so i decided today that’d i’d finally sit down and watch it today. While i am absolutely blown away and disgusted that what is happening in uganda (or was happening in uganda and now elsewhere according to some sources) is happening, i just can’t help wishing that people always acted like this when it comes to matters like these.

Without sounding all too “environmental warrior”, i just can’t help but to feel sad that with all the amazing documentaries that are out there about the environment, and with all the data that there is to show how utterly we are abusing our earth, why aren’t we making the same effort? After all, that truly affects every single one of us. 

We are all really, in one way our another, environmental Joseph Konys. And it needs to stop. So stop it.

Sorry about the long text post, hope someone took some time to read this.

5 things you may not have known about the ocean. 1. While its commonly known that the ocean covers something like 71% of our planets surface, it contains within it 99% of the habitable space on earth. Within this 99% as much as 95% of the life on earth is found.   2. 90% of the ocean is considered “deep” (over 2000 meters) and the average depth of the ocean is around 3795 meters. The deepest point (the Challenger Deep) is 10,916 meters. That’s as much as 1.23 Mount Everests. The pressure of the water on top of you at this point is equivalent to supporting 50 Jumbo Jets by yourself.   3. Only 10% of the sea has been explored by humans. In this 10%, around 200000 species have been described: it is estimated that as much as 30 million species may remain undiscovered.   4. The largest animal ever to live on this earth is the Blue Whale, measuring in at 30 meters long and weighing 180 tonnes (although the Bootlace Worm can grow longer than a blue whale, with some being measured at 50 meters long and 10 cm wide). It is also one of the fastest aquatic animals, reaching speeds of 50 km/h (the fastest are Sailfish, clocking in at 110 km/h)   5. The ocean is being destroyed at an alarming rate: More oil reaches the oceans as a result of leaking cars every year than the BP spill, and as much trash is dumped in the oceans each year as fish are taken out. Around 100 million sharks are killed yearly, 30% of these for their fins and the rest as by-catch.

5 things you may not have known about the ocean.

1.

While its commonly known that the ocean covers something like 71% of our planets surface, it contains within it 99% of the habitable space on earth. Within this 99% as much as 95% of the life on earth is found.

 

2.

90% of the ocean is considered “deep” (over 2000 meters) and the average depth of the ocean is around 3795 meters. The deepest point (the Challenger Deep) is 10,916 meters. That’s as much as 1.23 Mount Everests. The pressure of the water on top of you at this point is equivalent to supporting 50 Jumbo Jets by yourself.

 

3.

Only 10% of the sea has been explored by humans. In this 10%, around 200000 species have been described: it is estimated that as much as 30 million species may remain undiscovered.

 

4.

The largest animal ever to live on this earth is the Blue Whale, measuring in at 30 meters long and weighing 180 tonnes (although the Bootlace Worm can grow longer than a blue whale, with some being measured at 50 meters long and 10 cm wide). It is also one of the fastest aquatic animals, reaching speeds of 50 km/h (the fastest are Sailfish, clocking in at 110 km/h)

 

5.

The ocean is being destroyed at an alarming rate: More oil reaches the oceans as a result of leaking cars every year than the BP spill, and as much trash is dumped in the oceans each year as fish are taken out. Around 100 million sharks are killed yearly, 30% of these for their fins and the rest as by-catch.

Irrelephant wanted some information on Sea Squirts/ascidians, so here we go. Prepare for some proper marine science.

I think ascidians are actually somewhat ignored, they’re some very beautiful animals. Consisting of around 2300 species it’s quite a diverse class although they all have some common characteristcs: They’re all sessile (attached to a hard substrate), they’re all filter feeders (meaning they filter out organic matter from the water column) and unlike other similar Tunicates they have a much tougher tunic made of polysaccharides. They can either be solitary or form colonies several meters in diameter. They have a relatively simple nervous system, with receptors for chemical changes, light and touch. All are hermaphroditic and capable of both asexual & sexual fragmentation. 

Interestingly, Nudibranchs (amongst other animals) feed on them, but also use them as a substrate for egg attachment. 

Due to the incredible filtering capabilites of these animals, they’re incredibly sensitive to pollution.

As for some interesting species, Polycarpa aurata and Rophalaea are incredibly pretty, but Didemnum (shown above overgrowing green algae) species might be more interesting due to it being a major invasive species (and only one of the many invasive sea squirts) and generally a big nuisance.

5 favourite cephalopods, no.5:

Cephalopods are an amazingly diverse class of animals, but out of all of them there is one which i just can’t help loving. It isn’t the small and cute Hawaii Bobtail Squid, it isn’t the absolutely terrifying Vampyroteuthis infernalis (otherwise known as the Vampire Squid from Hell). It’s the majestic, incredibly intelligent and also somewhat terrifying Humboldt Squid, Dosidicus gigas. 

These animals can reach lengths of 1.75 (and that’s just the mantle, so it doesn’t include the head, arms or tentacles) and weigh as much as 50 kg. They hunt in shoals of up to 1500 indivudals, and usually reside between 200-700 meters.

Divers often describe them as incredibly curious animals (although this curiosity may be mistaken for agression, having a 2 meter long squid with hooked tentacles feel you up wouldn’t exactly make you feel great). They’re the only invertebrate known to hunt in shoals and communicate with each other, they even show hunting strategies. They’re almost like the killer whales of cephalopods.

Sadly, studies have found that ocean acidification may hit the Humboldt hard: it was found that if acidification continues increase at the same rate metabolic rate may decrease by as much as 30% and activity levels by almost 50% by the end of the century.

If any animal on earth, D. gigas is truly a masterpiece of evolution, and that is why it’s my favourite of all time.

Of all the zooplankton, there is one that’s just a bit scarier than all the others. Chaetognaths, or Arrow Worms, are around 120 different species of predatory, planktonic worms. While they only grows to a max length of around 120 mm (which quite large for zooplankton) it’s an incredibly efficient predator. They capture pray by extending massive hooks out of their oral openings and simply swallow smaller creatures whole, often immobilising them with neurotoxins. I’m glad i’m not plankton, wouldn’t want to meet one of those.

2011 - Shark attack year?

A few days ago University of Florida released its annual shark attack report, and shark attacks are declining. Interestingly, shark attack fatalities are highest they’ve been in almost 20 years. Out of 75 attacks last year, 12 were fatal (16%), which doubles 2010s mere 7% (bearing in mind there were 79 confirmed shark attacks 2010).

Why?

Well, i have a couple of ideas. For starters, people are travelling more often and to more remote areas. It’s a lot easier to survive a shark attack if you don’t bleed to death before you get to the hospital: a lot of deaths attributed to sharks are as a result of blood loss. Sharks more often than not let go of people when they realize we’re not food.  

Secondly, as global warming and overfishing increase, pray is becoming increasingly scarce for sharks, and they may simply strike out of extreme hunger (and will probably not let go of you as they’re quite intent on eating you, resulting in imminent death).

You shouldn’t be afraid to get in the water though: fact is you’re more likely to be killed pretty much by anything (or anyone, for that matter, in the US alone approximately 15000 people were murdered in 2011) else; last year 26 people were killed by lightning and in the UK 171 people died from work related injuries. You’re more likely to end up dead in a car accident on our way to the dive site, so no worries.

Above: the four sharks that are most commonly found to be aggressive towards humans. Left to right, Top to Bottom: Bull, Great White, Oceanic White Tip & Tiger Shark.

Through the ice!

After having drilled through 3623 meters of ice, the Russians have finally reached the sub-glacial Lake Vostok. This could prove to be incredibly interesting: It’s thought that if life, at any level, is found in a lake of this type it may very well be that there is life on Europa (one of jupiter’s moons, thought to have life) and on other similarly constructed planets and moons.

Lake Vostok is interesting for a number of reasons: It is thought to be supersaturated with oxygen and nitrogen, that is, it contains about 50 times the amount you’d find on earth, and even though the Lake Vostok base station has recorded the record low temperature of all time on earth (-89c), the lake remains liquid due to geothermal activity beneath the 3 kilometers of ice. Because of all these conditions; the supersaturation of oxygen, the complete lack of light and the geothermal energy it is thought that life may be found there that has never been observed before. Although it is under 3.6 km of ice, in 2005, researchers also recorded tides with a range of about 12 mm.

On another note, while things like these may lead to new insights about many different things, is it really right for us to drill down and pollute an environment like this that hasn’t been touched for 20 million years? You never know how sensitive ecosystems like these are. Something to think about.

Above: the Lake Vostok Station, location of Lake Vostok, & diagram of Lake Vostok.

The Shark and the Cod.

There’s been a lot of talk recently about Island Burgers, who apparently thought it’d be a good idea to start selling shark burgers. There was quite a bit of response surrounding this from twitter/tumblr/facebook. This is great, i definitely don’t want to see commercial shark fishing increase, theres just one thing that bothers me.

Most shark species are listed by the IUCN as Vulnerable. Due to this, large hotel chains in asia have stopped selling shark fin soup recently. 

So, what other species of fish are listed as vulnerable by the IUCN?

Well, the Atlantic Cod is. I feel like a similar response is missing to, say, 8500 fish and chips shops in the UK which sell cod? Not to mention Haddock, which is also listed by the IUCN as vulnerable?

by 1990 Atlantic Cod stocks had declined by 95%, and even with new fishing policies in place stocks show little evidence of recovering, and if they are they’re recovering very slowly and simply fishing less isn’t going to be enough.

The Cod will grow up to 2 meters long, 95 kg, and live for up to 25 years: it, like the shark, is an apex predator and composes an incredibly important part of the atlantic food web. Just because it’s a more common fish to eat, and may not stand out as much as a giant shark, doesn’t make it any less important.

Eat some Mackerel instead.

To kill a whale

During the 1980s, a technique was being developed by the US navy to detect submarines - a sonar, which unlike regular sonars (which rely on sound created by other vessels) worked through emitting a high power, low frequency sound and then listening for returning echoes. The noise emitted was around 230 decibels, which is around 10,000 times louder than a passenger aeroplane taking off. 

As you might imagine, this had some severe effects on marine life: 

It was shown that some animals further away from the source were deaf (which is a drawback for animals which rely on being able to hear for reproduction and even feeding sometimes). Closer to the source, 13 Cuvier’s Beaked Whales were found washed up on shore with severe gas embolisms  and haemorraging as a result of the pressure waves created by the sound.

180 decibels causes permanent death of hearing tissues in humans, why should the marine environment (which is even more sensitive to loud noises, due to the nature of water) be exposed to it? surely any technique which made use of such loud noises would be banned on land.

Above: How active sonar works, gas embolism in a dolphin liver and a Cuvier’s Beaked Whale.

Could the whale really have swallowed Jonah?

The biblical story of the whale that swallowed Jonah is relatively well known, but could it actually have happened? in the bible, Jonah is swallowed up by a giant “Leviathan” (which could be either whale or fish), but if this really did happen, what kind of whale or fish could this possibly be? Read on.

Considering that the Leviathan would have to be rather large, we might consider such things as Killer Whale, Whale shark and Sperm Whale. Why not Blue Whale or any other kind of Baleen Whale? The fact is that while baleen whales are the largest organisms on the planet, their throat is only the size of a large grapefruit. The same goes for Whale Sharks. Therefore, Jonah could not fit. Killer Whale then? improbable as well, he would probably have been torn to shreds as killer whales generally tear their food up if it is too large (which we may assume a human body to be, unless this is an exceptionally large orca). That leaves us with the Sperm Whale. So could it have?

Yes, it could have. While fisherman tales maybe aren’t the most trustworthy, there have been several accounts from American and British whaling vessels of fishermen being swallowed whole by Sperm Whales (They dont chew their food, and have large enough throats and stomachs to accomodate a human being). One story tells the tale of a fisherman who was swallowed by a giant sperm whale: the whale was found two days later and killed, and in opening the stomach they found the man was unconscious but still alive, with severely bleached skin, no hair and nails (as a result of the acids).

So could the worlds oldest fisherman’s tale be true? it very well could be. What do you think?

While the 7 meter long Greenland Shark is interesting for many reasons, i find the inuit legend behind it very cool. 

Inuit mythology tells the tale of Sedna, the god of sea and marine animals. Legend is that her father, angered by her marriage to a dog throws her into the sea. Attempting to crawl back into the kayak, her father cuts her fingers off and each finger becomes a marine animal, one of which became the Greenland Shark.