Save Our Seas Blogs » journal paper

Using local ecological knowledge to identify shark river habitats in Fiji

Juerg Brunnschweiler — Tue, 18 May 2010 09:06:47 +0000

A while ago I blogged about our attempts to find out more about the occurrence of sharks in Fijian rivers. The results from the interviews with locals living along various Fijian rivers have now been published in Environmental Conservation. I will present parts of this paper including additional results from our shark fishing surveys in rivers on the southern coast of Viti Levu at the upcoming Sharks International conference in Cairns.

The Shark Reef Marine Reserve: a marine tourism project in Fiji involving local communities

Juerg Brunnschweiler — Mon, 03 Aug 2009 11:22:47 +0000

Shark Reef marine reserve in Fiji. Photo: Klaus Jost

It is with great pleasure that I announce the publication of a paper published in the Journal of Sustainable Tourism that reports on the concept, implementation and success of the Shark Reef Marine Reserve in Fiji. The Save Our Seas Foundation has been supporting this small-scale conservation project in the South Pacific almost from the beginning through the funding of the Bull Shark Tagging Programme that uses Shark Reef Marine Reserve as a superb site for field work.

Instead of convincing local authorities to protect Shark Reef by first providing scientific data on, for example, species occurrence and/or abundance we chose to tackle the other end: have the site protected first and then do the work. This is possible in a place such as Fiji where the local villages own certain reef patches. Approaching them back in 2002, we convinced the local authorities that they should place a fishing ban on parts of Shark Reef which would be used by a single dive operator that offers an exclusive shark diving product to divers. As a compensation, divers would have to pay a marine park levy paid directly to the eligible villages. As you can see in the paper, this has paid well for both, the local villages as well as the dive operator. Additionally, Shark Reef Marine Reserve has become home to the Bull Shark Tagging Programme. To date, we have attached 14 pop-up satellite archival tags to bull sharks (to be continued this month) and dozens of acoustic transmitters to different shark species. It’s a great place not only for sharks, but also for scientists and divers! If you ever have the chance visiting it, do it!

Thanks to the Save Our Seas Foundation for its great support!

Tracking bull sharks with hand-fed intra-gastric acoustic tags

Juerg Brunnschweiler — Thu, 18 Jun 2009 09:32:32 +0000

In principle, there are two ways to equip sharks with acoustic tags: you can either attach the tags externally or internally. For both methods there are good examples to be found in the scientific literature. If done internally, you would usually catch the fish for surgical tag implantation. An alternative method can be feeding acoustic transmitters to sharks. Stomach tagging can be an interesting option and it allows you to, for example, monitor the stomach temperature of the animal in addition to obtaining presence-absence data. However, the indigestible tag will eventually be regurgitated, most likely via stomach eversion, and therefore tracking time is limited. In order to feed a tag to a shark, all you need is the tag wrapped in bait and a site where you know you can attract the sharks close enough to a feeder. There’s no better place than the Shark Reef Marine Reserve in Fiji to test the feasibility of stomach tagging and to estimate tag retention time. And so we did. The superb photograph on the right (taken by Klaus Jost) gives you an idea of how it looks when you hand-feed a tag to a good-sized bull shark in Fiji.

A paper that is published in Marine and Freshwater Behaviour and Physiology reports the results of our attempts over the past years and shows that fed acoustic transmitters or sensors are viable tools to collect presence-absence data or physiological parameters of free-ranging sharks. What I found is that the minimum tag retention time ranged from less than 24 hours (bull shark) to 34 days (tiger shark), and bull sharks could be tracked for a minimum mean duration of 6.8 days. This is not a long time, but good enough to address some of the questions we try to answer. And as you can read in the paper, some of the bull sharks were double tagged with a stomach tag and an externally attached acoustic tag. We also attach acoustic tags externally to get longer tracks which helps to get information on presence-absence of individual bull sharks over a time scale of months or even years. I hope I can tell you more about these results soon. Keep watching this space!