Lakes and Oceans

Awesome xkcd cartoon today about the relative depths of lakes and oceans.

 

Whale Tail

This is the tail end of a baby Humpback Whale who cruised past us, when I say cruised I mean mobbed us, three people go hit (there was no damage). I caught a picture of its’ tail which was about 5 feet wide.

You can see the front part of the whale here.

Eye Contact

I had the opportunity to get on a boat going to the Silver Banks which are located north of the Dominican Republic. There was a group cancellation and I jumped on (there is usually a two year waiting list for this trip.)

Humpback whales migrate from the North Atlantic down to the Silver Banks to raise their young for three months at the start of the year. So there is an opportunity to get in the water and swim with them.

This is a young calf (still 12 feet long) who came right up to me to check me out.

It has been a long time since I posted something about diving, in fact it has been a very long time since I had been diving until a couple of months ago when a block cancellation opened up room on a boat to the Silver Banks to snorkel with Humpback Whales.

This is a very sought after trip, the whales are on the Silver Banks for the first three months of the year, and the number of people who can visit is strictly controlled (880 people a year).

This was a wonderful trip, and I managed to get a few pictures.

 

NewImage

Study Confirming The Obvious About Sharks

Ars Technica does a good job of summarizing a study on declining shark populations. However I think the study is too tentative in identifying causes and effects. Simply put sharks are disappearing because of overfishing (for shark fins, once those are removed from the shark, it is thrown back in the sea to drown). The numbers being fished every year are up for debate, the office number is 38 million, realistically that number is probably closer to 70 million, and I have seen estimates of 100 million (probably for effect.) Over the past 20 years there has been a 50% decline in the global shark population. Even if fishing were to stop now, it would take a long time (a human generation or more) for stocks to get back up to ‘normal’ levels (say the numbers we had 20 years ago) because sharks take a long time to reach sexual maturity.

The effects of this reduction in the top predator are already being felt. For example there has been an increase on the stingray population which creates pressure on the mollusk population, and a large increase in the number of Humboldt Squid in the sea of Cortez. And for all intents and purposes, the Mako shark population on the east coast of the US is now non-existent.

Unfortunately the trends are clear, if this de-population goes on, sharks will be reduced to very small numbers in my lifetime, and the best chance to see one will be either the aquarium or in pictures.

 

Good-bye Shark Week? Large sharks in decline due to fishing:

Sharks have been honed into efficient predators by over 400 million years of evolution, but that didn’t prepare them for commercial-scale fishing. Sharks, skates, and rays are fantastically abundant in unexploited parts of the ocean, but a new review shows that even light fishing—both targeted at sharks and other species—can send populations into a tailspin. Large, top-predator shark species appear to suffer the most, and their dwindling numbers are drastically affecting many marine ecosystems.

Utila Sunset

This is not strictly a scuba diving but it was taken from the sun deck of the dive boat we were on. I was talking to some friends who had their back to the sun so I was watching the sun going down and I had to stop the conversation and pick up my camera to shoot this as the sun was turning the sky and the water to fire. I took about 15 shots and this is one of the better ones.

It was the penultimate evening of the trip, we had one more night dive that evening which got called off because the water was full of sea wasps. Actually strictly speaking the dive was not called off, the captain told us we were welcome to dive if we had the guts, but given how many sea wasps there were none of us had the guts. There were hundreds of them in the first couple of feet of the water column.

Goodbye Bluefin Tuna

I was deeply disappointed to see that the UN rejected a ban on the trade of bluefin tuna on March 18th (see “Bluefin tuna: Eaten Away” in the Economist and “U.N. Rejects Export Ban on Atlantic Bluefin Tuna” in the NY Times). The article highlight the voting shenanigans that we used by the Libyan delegation to effectuate this rejection.

Let’s face it, with idiots like that in charge of conservation, bluefin tuna is as good as extinct. From the Economist:

The outlook for the bluefin tuna is not good. Scientists already agree that the population is crashing, and that quotas allocated to fishermen remain too generous to give any reasonable degree of certainty of a recovery. The extent to which illegal fishing can be brought under control will also have a big impact on whether the population has a chance of recovering.

What I can’t understand is that the countries who rely most on fishing for food and trade are the least likely to implement sound fishery management practices. I have to wonder if these people have given thought to how they will make a living once the fish are all gone?

Tuna, Perhaps?

Back to the Cocos Island for this one, we were on Alcyon when these tuna came speeding through, and when I say speeding, they were really speeding. I am pretty sure that they are a kind of tuna, and were pretty large. One of them had had a run-in with something large.

On a similar topic, I was sorry to see that Japan is resisting a proposed fishing ban on bluefin tuna. Indeed the bluefin tuna is close to extinction:

The U.S. government said this week that it supports a proposed ban on international trade of Atlantic bluefin tuna because the species is at risk of extinction. The adult population of eastern Atlantic and Mediterranean bluefin has plunged 74 percent in the past 50 years, much of it in the past decade. In the western Atlantic, the population has fallen 82 percent.

I am not sure what their problem is, if the numbers above are true then bluefin tuna are close to collapse. Another thing that people don’t really consider is that bluefin tuna migrates between eastern Atlantic and the Mediterranean, so overfishing in one sea directly impacts the population of the other.

This particular quote really got me, the United States changed its position because population is close to being wiped out, equating Okinawa or Toyota with this is just a smoke-screen. The truth of the matter is that the population is close to collapse and will do so if not protected. At which point Mr. Saito will have to retire, as will all the other bluefin tuna fishermen, and bluefin tuna will be a distant memory:

“The United States just changed its position,” said Takashi Saito, 76, a bluefin wholesaler for six decades. “I feel that what happened with Okinawa and with Toyota is being extended to the tuna issue as well. It is just Japan-bashing.”

More evidence of this short-sightedness:

In the market, fish wholesalers agreed that global restrictions in the bluefin catch make sense, when they are based on academic data. But they said there is no way Japan can go along with a bluefin ban.

“There is no choice for the Japanese government,” said Saito. “We Japanese eat tuna.”

The truth is that soon the Japanese will not longer eat bluefin tuna because there won’t be any left.

Close up of a Nurse Shark

This is another angle on the large (pregnant) Nurse Shark I posted last september. This Nurse Shark has been swimming around us and decided to take a rest tucking its head under a coral head, the back end of the was out on the sand around the coral head.

I was pretty sure it was pregnant when I saw it turn right in front of me, you could see from the stomach that there was something substantial there (all divers were accounted for so not that) and one of the dive master signaled to me that it was indeed pregnant (there is no sign in the dive book for pregnant but it was obvious to me). Also there was slight wound on its side, it had gotten in a scrape with some other sea creature or maybe a human, hard to tell, but it was there, you can see the bump to the left of the remora’s head in this picture.

I felt really lucky that it had settled down and I was able to approach it very closely and got pictures from both sides and some nice close ups of which this is one. I don’t put the full size image on Flickr but you can see the texture and color of the scales, and the eye. I was able to spent about 2-3 minutes and took 17 shots.

Before And After II

Continuing in the before and after series (previous post), here is a Caribbean Reef Shark which I photographed in the Turks and Caicos.

We had put out an ‘attractor’ for the sharks (namely a small piece of fish in a metal box) and we had five to six circling around and swimming amongst the divers. In those sorts of situations I tend to look at the patterns the sharks follow, place myself in their path and wait. They are quite inquisitive and will come by quite close to check out the divers (insert your own jokes about tasty morsels here) at which point you can get some really nice shots as they stream by. I had positioned myself on the seabed very close to the attractor and was watching sharks come by and it stuck me that I could get better shots by lying with my back on the seabed. Indeed I had been noticing that the sharks would just swim over me. So I turned over and started taking shots.

This is the initial shot of a shark as it swam over me. The shot is tinged with red because I had calibrated the white balance on the camera my shooting down at the calibration slate and now I was taking shots upwards so getting more sunlight from the surface (we were at about 50 feet). You will also notice some ‘snow’ in the picture and a diver’s fin. Unfortunately the camera I was using is pretty slow focusing so I lost the nose of the shark.
Caribbean Reef Shark (Master)

So cleaning up the picture, I adjusted down the red, brought out the blues a little, better contrast, then removed the ‘snow’ and the errant fin. The result is a fairly decent blue for the water, though I could have done a better job on the texture on the left of the shark, there is some blotching going on. One thing that was really brought out are the sharks “Ampullae of Lorenzini” all across the shark’s snout. Basically they are a network of electroreceptors, which you can read up on on Wikipedia.
Caribbean Reef Shark

There are some divers who will massage shark’s Ampullae of Lorenzini which makes them very docile, but I was not about to attempt that.

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