Newsletter

The next meeting is the October General Meeting which will be held at the Conservation Centre, 120 Wakefield Street on Wednesday 17^th October commencing at 7.30pm.

The Jewels Of The Sea Project is scheduled to finish at the end of October so our Speaker will be Tony Isaacson with his final report.

Biology professor Amanda Vincent emerges from the chilly, murky water of Sydney Harbour with a scuba tank on her back and a grin on her face …She is surprised to have found a seahorse today – they normally disappear during the colder months, presumably into deeper water.

The world’s foremost seahorse expert eases the creature out of a mesh specimen bag and holds it gently. "They’re the only fish that hold your hand," says Vincent. "That’s my favourite line." … It’s not he place you’d expect to see a scientist wade in from the shallows with a seahorse. The water looks dirty, rubbish laps up onto the sand each time a ferry passes, and noisy powerboats zoom by. But, she says, seahorses are more common in this area than we think …

"We don’t yet know how well they survive in polluted conditions," Vincent says later. "But the fact they are here is quite something. Many other species wouldn’t stick around – you’ve got raw sewage flowing into the water a few hundred metres away."

… At least ten of the 32 known species of seahorse live in Australian waters …"Where there’s seagrass," says Vincent, "there are commonly seahorses. They’re just such cryptic animals, people don’t notice them. They’re found in places where most of us swim all the time – seagrass beds, shark nets, seaweed – but they’re very well camouflaged." They are found around the world, usually in shallow temperate and tropical waters, but some species have been trawled in deep ocean habitats from more than 150m down.

Seahorses are monogamous and most species … pair up early and are thought to form partnerships for the duration of the breeding season, if not for life. Males and females meet each morning in the seagrass beds to entwine their tails and perform intricate greeting dances and colour changes. When it is time to mate, couples engage in hours of dancing, twining together, throwing their heads back and nudging each other before finally mating in open water off the seabed, where they are vulnerable to lurking predators.

After mating the male fertilises the female’s eggs, now snug in the brood pouch on his tail. He provides his unborn young with protection, nutrients and oxygen for between ten days and six weeks before going into labour, which can last several hours, expelling up to 1500 fully formed and independent young into the water to drift with the current.

Seahorses have tiny territories. Males will stay within a space as small as a square metre, while females range over larger areas and return to the male each morning for their greeting ritual. Their response to predators is not to flee, but to tighten their tails’ grip on whatever they are attached to and draw their heads into their bodies.

They are ambush predators and rely on intricate camouflage, growing extra skin filaments to match surrounding habitat and changing colour to help catch their prey. A seahorse will remain completely still until a meal small enough (a tiny shrimp, fish fry, invertebrate or crustacean) drifts within reach. In a movement faster than the human eye can register, the seahorse strikes and sucks the animal into its long snout, to be digested whole. They don’t have teeth or a stomach, and they’re voracious – aquarium studies have observed two-week-old seahorses eating 3600 baby shrimp in just ten hours.

But according to Vincent, the list of things we don’t know about seahorses is far greater than what we do know. We know that the male of the species goes through a true pregnancy, but we don’t know what the male-to-female ratio is at birth, how their diet changes as they grow, at what age they start reproducing, or how long they live. Scientists infer that an average of two young from each pair survive to breed, enough to keep the population of a particular species stable.

Despite evidence that seahorse numbers are falling around the world, we don’t know how serious the decline is because no earlier studies exist to make a comparison. We know that seahorse populations that have been fished out take a long time to replenish because of each animal’s small area of movement, but we don’t know how large marine protected areas should be because of questions about the size of wild seahorse populations and whether or not they migrate.

… In Australian waters, seahorses are targeted by only relatively few aquarium fishers, but they are the victims of accidental by-catch in non-selective fishing gear used to trawl for prawns and the like, and their habitats are under threat. In a typical prawn trawl, Vincent says, more than 80 per cent of the catch can be species other than shrimp. Australia is the biggest supplier of piphorse[s], … to Hong Kong. …In addition, seahorse habitats in Australia – coral reefs, estuaries, seagrass beds and mangroves – are among the most threatened by pollution and degradation.

Vincent says Australia could become an even more important safe haven for seahorses, as many of the species found in tropical waters here are also found in South-East Asia, where they are heavily fished. That is one of the reasons Project Seahorse chose to base a significant operation here as soon as the funding materialised.

In a plush Sydney hotel at last month’s launch of Project Seahorse’s Australian program, Vincent is grinning again, but not because of a seahorse. Guylian, the Belgian company famous for its seahorse-shaped chocolates, recently sought out Project Seahorse and offered $A1.4 million for worldwide research to spend as Vincent saw fit. Such an open-ended offer is rare in corporate philanthropy today, but Vincent’s non-threatening approach to conservation proved persuasive.

"Our main objective in Australia is to maintain the degree of diversity we already have in seahorses here," according to Dr Keith Martin-Smith, Project Seahorse Research Fellow for Australia. "By-catch issues have an effect on this, as do aquaculture and aquarium target fishing to an extent, and the conservation of marine ecosystems such as mangroves, estuaries, coral reefs and seagrasses. We will be continuing dialogue and building relationships with stakeholder groups involved in all those issues."

But Project Seahorse has already formed a productive relationship with Australia, one that may make a significant impact on marine conservation on a world scale. …At its last meeting, CITES voted for the first time to take action on seahorses and pipefish. A CITES working group, chaired by Vincent, will hold an international technical workshop, consult all countries and make recommendations for action. Australia has already offered to contribute financially to this workshop.

"What we produced through a joint effort was a first-ever move by CITES to act before an animal became endangered enough to be forced onto the lists of controlled species," says Vincent. "In a way, to slap trade bans on an animal is to admit you have already failed – you haven’t managed to prevent it from becoming endangered." And seahorses have opened the doors of possibility for many other marine species to be protected in the same way.

"Seahorses are a potent symbol for marine conservation, and they live in the world’s most important habitats, and certainly the most threatened marine habitats. When people think of seagrasses having seahorses in them, there’s suddenly a whole new public interest.

"By working with seahorses, we’ve developed expertise that allow us to speak out on by-catch issues, on unusual and non-food marine trade, on habitat protection, on fisheries management, on aquaculture; all this is packaged around seahorses, which everybody loves and instantly recognises. Seahorses have allowed us to play in almost any area of aquatic conservation.

"And to top it all off, they’re really cute."

In the article in August newsletter about soft, transparent jelly things I said that the Portuguese man o’ war and the By-the-wind-sailor were the same organism, but I have been corrected. I did not look at the book properly and indeed they are quite different. The Portuguese man o’ war is considered "by some authorities" to be different from the Bluebottle and hence they have different scientific names. The Portugues man o’ war is Physalia physalis and the Bluebottle is Physalia utriculus.

The By-the-wind-sailor, however, although still a hydroid is not a siphonophore. Its scientific name is Velella velella.

I recently stumbled across the CAPP’s shop in Port Adelaide. "CAPP" stands for Community Action for the Port and Peninsula. That is Port Adelaide and Lefevre Peninsula. It is a new name for the group since it was first known as Community Action for Pelican Point when they were trying to stop the new power station from being built at Pelican Point. The Port Adelaide shop is called the Community Action Shop. It was opened in June this year. It is well worth a visit and seems to be open on weekends. The people working there are very friendly and helpful. There are interesting displays to be seen outlining CAPP’s work and concerns, including a photographic exhibition of the Port River and its environs. You can pick up information and the group’s newsletter "The Pelican Review". Amongst some of the information that I received was a submission for an eco-tourism development at Pelican Point. I enjoyed reading "Pelican Point, An Opportunity" before I realised that it had been written by an old acquaintance of mine, Wilf Wear. According to the submission, CAPP is proposing an eco-tourism park at Pelican Point. The proposal includes wetlands, an eco-tourism centre and a cultural interpretive centre. The group welcomes new members to help and support them. Meetings are held every Monday night (that’s keenness for you!) and they have a guest speaker every third Monday of the month. A flyer from the group says that they are "local people working together for local issues". They want "to leave a better place for . . children to live and a place that has clean air, clean land and clean water". The flyer gives details of their Vision, Mission and Aims (Community Charter). Their vision is "to establish the Lefevre Peninsula and surrounding environs as areas of best environmental practises". Their mission is "To protect the health, welfare and lifestyle of the residents of the Lefevre Peninsula and adjacent communities, through strategies that have as their focus the protection and preservation of the flora, fauna, land, air and marine environment of the region". CAPP can be contacted by telephone on 8240 5365. Their postal address is PO Box 244 Semaphore 5019 and the shop is located at 216 St Vincent Street, Port Adelaide. I have filed the information that I received in our library (mlssa No.3023). I hope that we are all able to assist CAPP with their work in some way.

Library Officer 2000-2001

On ABC Radio on 13^th August there was a discussion regarding the blackmarket trade in seahorses. Linda Mottram was talking to Nicole Johnston. Below is a transcript from the broadcast. Details were passed on to our Society via "Wetstuff" from the Marine & Coastal Community Network. Society members will have received this information from "Wetstuff" when it was e-mailed to them. The e-mail (and the transcript) had two words missing because they were inaudible from the broadcast. I believe that the two words were "earbones" and "earbone" so I have added these words to the details below. I was able to add the two words that were inaudible because I had saved a report from the 15^th August issue of the Advertiser which discussed this topic.

LINDA MOTTRAM: Concern about the poaching of wild seahorses is forcing companies who farm the tiny creatures to start staining their organs. Tasmanian based Seahorse Australia, the world's first seahorse farm, has started a staining trial, hoping that it will allow export authorities to distinguish between legitimate, farmed seahorses and those stolen from the wild. Nicole Johnston reports from Hobart that with seahorses fetching up to $20 each, the growth of an international black-market trade is unsurprising.

NICOLE JOHNSTON: Seahorse Australia has produced more than 200,000 hatchery reared seahorses over the past three years. But it has the capacity to do half a million a year. Demand from the Chinese medicine market for these creatures is now outstripping supply and senior marine biologist, Rachelle Hawkins, says authorities don't even know how many seahorses are being illegally caught in the wild.

RACHELLE HAWKINS: Well, the exact numbers are unknown, which is perhaps the scariest part of it. We know that between 20 and 40 million seahorses are used annually in traditional Chinese medicine. Now, that’s a very wide window, 20 to 40 million. However, now that seahorses have become so popular for both the aquarium trade, and also for Chinese medicine, it is important that seahorses are not being taken out of the wild and used for this purpose.

NICOLE JOHNSTON: So, are the seahorse stocks in the wild starting to run low?

RACHELLE HAWKINS: They certainly are. Our particular species, we're not concerned for Hippocampus abdominalis, which is our species in Tasmania, simply because we know it can be farmed quite easily. However we know that the Asian waters... the seahorses in Asian waters are declining remarkably. It’s been well documented that fishermen in the Philippines and Vietnam, in the past, would have no problem fishing 50 every night. Now, they're lucky if they can pick out 10 or 20 in a week just because the numbers are running out.

NICOLE JOHNSTON: Rachelle Hawkins says to protect the seahorse the industry must find a way to distinguish farmed seahorses from those in the wild.

RACHELLE HAWKINS: The plan is that all the hatchery reared seahorses will be stained, their earbones will be stained with strontium chloride for the purpose of when they are sold, any particular batch of seahorses that are on the market can be looked at by the authorities to determine whether they are hatchery reared or wild caught, simply by looking at that earbone. So we expect that every seahorse farm in Australia, and perhaps worldwide, will take on this form of marking, simply so that we can basically stamp out any poaching of seahorses from the wild.

LINDA MOTTRAM: Rachelle Hawkins from Seahorse Australia in

Tasmania.

The Star of Greece was a three-masted iron clipper ship built at Belfast in 1868. The ship was 227 feet long and sailed quickly around the world. She had been carrying wheat from Port Adelaide to the U.K. when she became wrecked at Port Willunga early in the morning of 13th July 1888. Seventeen lives were lost, making it one of SA’s worst shipping disasters. At the end of June 1888 the Star of Greece had just brought a 22-ton gun (7m long 9" breach loader) to Port Adelaide. The gun was to be installed at a fort being planned for Glenelg. The tragedy is that the fort was never built and two weeks later the ship left Port Adelaide only to sink at Port Willunga on Friday the 13th of July. Its fate could have been quite different had it not had to bring the unneeded gun to SA. The gun apparently sat in sandhills for something like a quarter of a century. It was never fired and just became obsolete.

Hi all!

Several people have been asking me for an update on our baby weedy sea dragons at the Aquarium of the Pacific. We have 17 babies that are 6-7 weeks old. They are about 3 inches in length and all doing well. We had a second weedy that became pregnant and has had 58 babies to date. These young are 1-2 weeks old and are doing very well. They are not yet on exhibit but they can be viewed by the public via a camera and monitor set up outside our adult exhibit. It has been so exciting to see these amazing animals grow up! If you have any questions, please feel free to contact me. Thanks for all the interest

and support!

Kristy Forsgren
Aquarium of the Pacific
100 Aquarium Way
Long Beach, CA 90802
562.951.1731

The swim bladder is the buoyancy control device of fish. It enables fish to conserve energy in a similar way divers do. That is, by using the buoyant effect of gas trapped within a bladder to create an uplifting force.

Situated within the major body cavity, the swim bladder is a bag that can be filled with gas, mostly oxygen. The way in which gas is created is interesting. At the front of the swim bladder is a special gas gland. It has a rich concentration of arterial blood vessels coming straight from the heart and gills. Special cells within the gas gland secrete lactic acid, a substance associated with cramp in human muscles. This lactic acid causes the partial pressure of oxygen to increase until it is higher than the partial pressure within the swim bladder. At this point, oxygen leaves the blood in the form of tiny bubbles of gas and leaks into the swim bladder. In summary, the oxygen is taken from the water, enters the gills and then passes through the gas gland into the swim bladder. During this process, it changes from oxygen dissolved in seawater to gaseous oxygen.

When the fish wants to out-gas (get rid of it), oxygen is released from the rear of the swim bladder. Fish are not very good at out-gassing quickly. A fish made to suddenly change depth runs the risk of a severe and, often fatal, pressure barotrauma. Deep-sea fish often die from gas expansion in the swim bladder as they are hauled up to the surface. Their intestinal organs are forced under pressure from the abdominal cavity, now filled with expanded air from the over distended swim bladder. For a fish to change depth it has to do so slowly in stages so it can adjust its buoyancy. This is one reason divers should not handle fish, especially Leafy Sea Dragons for example.

The extremely destructive practice of dynamite fishing kills the fish by destroying the swim bladder. The enormous percussion wave from the blast passes through the water into the fish’s body. The gas chamber within the swim bladder focuses the explosive force of the blast, tearing the internal tissues of the fish to shreds.

The Pineapple fish can squeeze the swim bladder to create audible sounds.

One interesting feature of fast swimming pelagic fish and sharks is that they do not have a swim bladder. Hunting often involves very rapid depth changes. For these animals, a swim bladder would only be a hindrance, causing life threatening buoyancy and barotrauma problems in pursuit of prey.

(This item is taken from "Australian Scuba Diver" July/August 2000)

http://ourworld.compuserve.com/homepages/BMLSS/

29 July 2001.