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California Academy of Sciences - Seahorse Sleuth 

June 30, 2009

Shark Bay but no Sharks (or sea horses)

From the Log of David McGuire, Field Associate

After speaking to a local Aussie who has been here a week, we camp at the pull off below the lighthouse. Lighthouse Bay is a narrow bay fringed by Ningaloo Reef just south of a series of tall Naval Radio towers. The reef extends into a smaller bay that has all the potential of a left hand southern hemisphere Malibu wave breaking on the coral reef flats.

Sea turtles nest here and our local friend said he observed what sounds might be a Loggerhead turtle laying eggs. We dove the outer reef after kicking nearly a kilometer offshore with the strong offshore wind, bottoming out in about 7-8 meters. No pipefish or sea horses observed here but there are lovely corals and diverse fishes including reef sharks, huge potato groupers, sea turtles and a palette of wrasses and soft corals. The kick against the current created by the offshore wind took nearly an hour and we crawled up the steep sand beach face like tired sea turtles after a long swim.

Exempt from city lights the stars are infinite and the Southern Cross and Magellan Kite are clear among the myriads. There are so many stars that our evening beach walk is lit by the star shine of the Magellanic cloud.

In the evening the wind has switched from the east to a stiff northwest and the boat dive we scheduled has been canceled. I was hoping to film the whale sharks that make this area famous for tourism, but the conditions did not allow.

Tantabiddi. Norah and I kicked out half a kilometer to the moored boats and dropped down in 4 meters. This bay looks like it is scoured by tides, although this is the neap tide of the lunar cycle, we still had a 3 –4 knot current: unlikely conditions for our animals to inhabit.

Wake of charter boat

The following day, we chartered a boat from a local fisherman who took us out to some small islands- the Rivoli- in the gulf of Exmouth. The currents and short chop of the shallow bay kicked up the sediments and we ended up moving to another site after an hour of diving. Our skipper, Ash, is quite a character and being height challenged, he sits on the overhead canopy for better visibility of the water ahead while steering with his feet. The second dive was silty and surgy with a building south swell making inspecting the coral ledges and patches of seagrass difficult. Again, none of our target fish were seen. Offshore the whale sharks ply the plankton, but we head inshore for another dive on the fringing reef called the Labyrinth where a dive master informed us they have seen ghost pipefish.

Norah

I would like to put a camera on Norah’s head. As my buddy, she swims ahead of me so I can monitor and film her as she searches, but she has seen several sharks, all quickly out of camera range by the time I come alongside. To me sharks are as attractive as seahorses and unfortunately, are threatened by many of the same influences: killed as bycatch, loss of habitat and targeted by the Asian luxury animal trade. On this dive I don’t see a shark or a seahorse, but an increasing surge from a building south swell. We scout the Exmouth Jetty that Dr. Allen Dekelboum -a longtime Academy associate and Dive Doctor- told us was an incredible dive location. The strong swell and heavy winds did not allow us to test the locale and we headed to deeper water.

The final dive of the day we drift off the anchor in several knots of tide at 20 meters over what is termed the sponge garden. Captain Ash must have missed the location because we see few sponges and the bottom looks scoured and barren with patches of small coral clinging to the substrate. The habitat and conditions are decidedly seahorse unfriendly. This bay has a history of intense bottom trawling for prawns and the fleet is still quite active. The fishermen claim that seahorses are recovered in the trawl nets and Healy made contact with their fisheries manager about sharing specimens. All bycatch is required by the fisheries to be discarded so Healy hopes to work through the permit process to obtain a few bycaught seahorses and pipefish from this region.

We have been diving for over a week now, underwater collectively for sixty hours searching hard but other than the Shark’s Bay specimens we have had little luck. Several of the species we seek have been reported by both our colleagues and in the literature so it is a mystery why we cannot locate the animals in some of the areas where we find ideal habitat.

Discouraged by the weather, and with limited time remaining, we decide to head south. Driving the long open road I count ten kangaroo carcasses in a kilometer but I am yet to get close enough for a good full frame image on my camera. These animals are quite shy, yet inexplicably are attracted to the road. Similarly the Emu, a large flightless bird much like an ostrich. We nearly run one of these huge animals down at sunset, narrowly missing another roadside carnage. Anecdotally, I am impressed by the absence of large predators and only large ravens and the occasional eagle feed on the roadkill. Australia once had a marsupial lion and wolf but those are long extinct and it is up to introduced animals and the automobile to prey on the large herbivores.

Emus

First stop, Kalbarri: a large forested area of rolling hills that most Australians would call mountains. This remnant of the ancient southern supercontinent of Gondwana is eroded and whittled down by eons of time. The road meets the beach at the mouth of the Murchison River, and again a rough unruly ocean meets our gaze. But we’re here to meet with Mike and Wendy, a couple that run the Sea Horse Sanctuary, a seahorse husbandry operation that supplies animals for the aquarium trade, thereby taking pressure off of harvesting of wild seahorses populations. Mike and Wendy are biologists that have been quite successful in breeding several species of seahorses as well as two colorful and charismatic species of pipefish. After a tour of their educational exhibits, they give Healy several specimens: Hippocampus angustus from Exmouth Gulf, a species of seahorse new to Healy’s DNA studies, and two species of pipefish imported from Indonesia.

Seahorses in aquarium

Seahorse Sanctuary

From Kalbarri we press on to try to and dive in Jurien Bay, a large natural bay several hundred kilometers north of Perth. Jurien Bay is the newest marine park in West Australia. All along the section of coastline we have touched upon protected areas. Like California, Australia’s marine parks are managed as a blend of levels of protection, with some areas permitting recreational fishing and other extractive activities, to “fish sanctuaries” allowing no fishing at all. Conversations with locals indicate that many areas have has been overfished and they welcome the protections, while others begrudge the closures.


Filed under: Uncategorized — hhamilton @ 4:11 pm

1 Comment »

  1. have you heard of a sea horse shark -my daughter needs to do research on this for school pse send me more info.
    thanks

    Comment by kavitha — September 8, 2009 @ 2:37 am

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