Kate's sawfish research and PhD

Hello NTFFSM,

Since the Sheep Station Stakes may be contributing to Kate's research, I thought it timely to let you know what she is up to.  She may comment on this, so hopefully I am right with the content.
Freshwater sawfish are critically endangered world wide and northern Australia is probably one of the remaining areas that has a reasonable ecologically sustained population, although still declining.  Anyone who has fished the Daly for more that 20 years would have seen a dramatic reduction in the number of juvenile sawfish stacked up at the crossing after the wet.
Kate's main aim is to determine if there is any conservation benefit to keeping and displaying threatened species such as sawfish in public aquariums.  In doing this she is attempting to quantify what a conservation benefit actually is.  The display of threatened species is allowed if there is a known conservation benefit, but that hasn't been quantified yet.
We have kept sawfish at the park since the early 90s.  They grow up to 7m long and soon outgrow our 25m long aquarium.  It takes them about 4 years to get to 3m long.  What then, do you do with a 3m long sawfish that has outgrown your fish tank.  Our solution was to release them back from whence they came.  The question is do they survive?  We have released a lot of sawfish over the years and have only tracked 4 using technology that allows us to keep pretty close tabs on them for about a month.  Of the 4 we have tracked we can only say that we are fairly certain that 1 has survived up to 23 days, the battery in the tag went flat after this period, so although it is an assumption, we are pretty confident that it did survive long term.
What Kate is proposing is to keep sawfish in captivity for a set period, then tag and release them at the site of their capture and track them for as long as possible (up to 25 days).  She will compare this to sawfish that have been caught, tagged and immediately released so she can compare the two treatments and see if the captive sawfish, a) survive and b) see if they use the habitat differently to the wild fish.  If they don't, it is fair to say that keeping sawfish in captivity is sustainable.  If they don't survive or indeed behave different to the wild sawfish, it might be prudent to stop the aquarium harvest.
So, there are 20 accoustic recievers being deployed along the entire length of the Adelaide River.  These recievers pick up the signal from a tag that is surgically implanted in the sawfish's body cavity. The internal tags last upwards of 2 years.  Another tag is stitched onto the dorsal fin that is emits a continuous ultrasonic beep that is picked up with a hydrophone.  The continuous beep lasts 25 days, and the tags are attached with dissolvable sutures so the fish only carries the tag until the stitches dissolve (theretically after a month).  This continuous tag is used for short term tracking.  We track the sawfish after it has been tagged for 48 hrs straight and then periodically after that until the battery dies or the tag is lost.
The second component to the research is to actually quantify what constitutes a conservation benefit.  She aims to do this by visiting public aquariums that keep these species and, by questioning visitors in a targeted survey, find out if their behaviour towards threatened species and indeed protecting their environment is actually enhanced because they were able to see these animals alive in a zoo or aquarium. 
This is expensive work, a set of 2 tags is around $600 and she needs at least 12 sets to make the project viable.  She is getting a lot of support and her project is being watched eagerly at the Federal level.  National Geographic has helped out, Fisheries, the Widlife Park and CSIRO are all involved and she has been accepted to present a paper at an International Shark Husbandry Symposium in Monterey in November.  Hopefully we can swing funds to go over to that. 
To date we have released a large female that was in the Aquarium here at TWP.  That was well covered in the national media a couple of weeks ago and we have caught tagged and released on wild juvenile.  This little female was caught in Marrakai creek and within 4 days had swum over 40km downstream.  We tracked her again over the weekend and we found the tag that had come off the dorsal fine 20km upstream from where she was last found.  That's about 60km in a week.  Far more movement than anyone had expected.

That's a baby sawfish at the TWP