Thread: Aus Day 2014 - WA off to a bad start... Shark cull

I am not sure how far north Great Whites go on the west coast but on the east coast they go to the Swain's Reefs in the GBR east of Mackay - that is about 20 degrees south. This is on their standard migratory path up and then down the east coast - when coming back down they get down to Bass Strait and then either turn east to NZ or west to SA, WA and South Africa.

They are definitely a cold water shark.

Also while "immature" (up to about 2.5m) they are solely fish eaters. As they mature they change to a mammal preference so it is unlikely that an immature Great White will attack humans.

Newcastle Forumites - any updates on the 2.5m Great White in Lake Macquarie. It hangs out off Pulver Is stealing fish off fisherman and has been seen jumping out of the water. When I was up there at Xmas the authorities were still working out what to do and public surveys were extremely positive to saving the animal with either leave it there or capture and take it back to sea - surprisingly there was very little support in killing it. I guess people have gotten used to the Bull Sharks which will have a go where this Great White is still a fish eater.

Cheers

Garry

Originally Posted by garrycol

I am not sure how far north Great Whites go on the west coast but on the east coast they go to the Swain's Reefs in the GBR east of Mackay - that is about 20 degrees south. This is on their standard migratory path up and then down the east coast - when coming back down they get down to Bass Strait and then either turn east to NZ or west to SA, WA and South Africa.

They are definitely a cold water shark.

Also while "immature" (up to about 2.5m) they are solely fish eaters. As they mature they change to a mammal preference so it is unlikely that an immature Great White will attack humans.

Newcastle Forumites - any updates on the 2.5m Great White in Lake Macquarie. It hangs out off Pulver Is stealing fish off fisherman and has been seen jumping out of the water. When I was up there at Xmas the authorities were still working out what to do and public surveys were extremely positive to saving the animal with either leave it there or capture and take it back to sea - surprisingly there was very little support in killing it. I guess people have gotten used to the Bull Sharks which will have a go where this Great White is still a fish eater.

Cheers

Garry

Gday Garry,

My main point was Andy's mate believed the white sharks were eating the asylem seekers, well most only get to christmas island, im not sure of its latitude, but what 12 south maybe. think maybe closer to 10 south.

Thats why I suggested his mate find another model of shark.

cheers Ean

New Zealand doctor James Grant fights off shark, stitches wounds, then heads to the pub - ABC News (Australian Broadcasting Corporation)

Hi Ean
Next time we catch up I shal point that out to him.
They are not chucking illegals down white pointers necks,they must be feeding the tigers or some other greedy critters
Andrew

Originally Posted by Ean Austral

Gday Garry,

My main point was Andy's mate believed the white sharks were eating the asylem seekers, well most only get to christmas island, im not sure of its latitude, but what 12 south maybe. think maybe closer to 10 south.

Thats why I suggested his mate find another model of shark.

cheers Ean

Yep - Tigers or Oceanics

Gentlemen, unfortunately I can not gain full access to the document I was after
I did gain access to a PhD Thesis, which I got the following information from.

I was able to gain some insight which shows that two different hook types were trialed, one being the traditional 'j hook' and the other being a 'circle hook' (circles back towards the shank more than a 'j hook').

Mortality rates upon collection generally dropped amongst most species of shark when using the circle hooks. Although there were two extremities of 100% mortality on circle hook catches, and 100% survival on circle hook catches. These were two separate species.



Here are some direct quotes from the thesis.

All potentially aggressive sharks caught alive were accommodated in a water-filled, wooden tank which was assembled on the deck of R/V Sinuelo, and transported towards the continental slope in order to remove them away from the area of risk. The distance and duration of the transport depended on the size and health of the shark, and some primary vital signs such as the contraction periodicity of gill openings and the maintenance of body equilibrium were continuously monitored to assure that the shark was released in good condition.

A total of 22 tiger sharks comprising 11 males and 11 females and measuring between 90 and 295 cm in total length (TL) were tagged and released off Recife, representing a total of 15 acoustic transmitter deployments and 16 PSAT-tag deployments (Table 7.1). Most sharks were released in good health conditions except for three sharks which did not respond when released and thus had to be assisted by one person in the water, who balanced them at the sea surface and pushed them upstream until they demonstrated an autonomous swimming capacity. Also, two other sharks could not easily maintain their biological position underwater by releasing time (i.e., they tended to turn with their ventral-side up) and so they were kept in the hook next to the boat until they exhibited enough strength to be released (Table 7.1).

After being transported away from shore and released, most tiger sharks reacted well and actively moved away from the boat. Notably, many specimens stayed visibly at the surface in slow swimming for a considerable time, as long as five minutes, before diving out of sight. One specimen first headed towards land but suddenly inverted its direction, ~20 m further, and returned to the boat always at the surface, eventually diving to pass under the boat in the direction of open sea.





These 22 tiger sharks were tracked between June 2008 - Sept 2011. Of the twenty two; seventeen recorded good overall health, three reported fair health and two reported poor health...






UNIVERSIDADE do ALGARVE Faculdade de Ciências e Tecnologia
Bioecology and movement patterns of sharks off Recife, Brazil: applications in the mitigation of shark attack hazard
André Sucena Afonso

Originally Posted by beagleONE

Gentlemen, unfortunately I can not gain full access to the document I was after
I did gain access to a PhD Thesis, which I got the following information from.

These 22 tiger sharks were tracked between June 2008 - Sept 2011. Of the twenty two; seventeen recorded good overall health, three reported fair health and two reported poor health...

But, did they return to shore?

Originally Posted by Mick_Marsh

But, did they return to shore?

An important bit that I neglected to look in to haha.
Long day at work...


***back to scroll through 297 pages of work***