Cayman Island Tiger Sharks: tagging data shows possible Caribbean migratory patterns

The Cayman News Service reported that three tiger sharks that were tagged almost a year ago in waters off the Cayman Islands have returned having roamed the wide waters of the Caribbean. The original tagging project was a joint effort between the Department of Environment (DoE), Marine Conservation International (MCI), the Guy Harvey Research Institute (GHRI) at Nova Southeastern University and the Save Our Seas Foundation.

The three sharks were tagged with satellite tags which can provide a variety of data in addition to basic positioning information. One of the three sharks spent a great deal of time cruising the coast of Jamaica; another has been in deep waters off the Cayman Islands; while the third shark spent the summer in the southwest, off Honduras and Nicaragua.

While not necessarily covering the same long "point A to point B" distances that have been reported with sharks like great white sharks and whale sharks, the data does show that the sharks can cover a considerable amount of territory and that these movements might constitute "migrations" if there is a schedule or pattern to their journeys.

Being able to verify that sharks frequent the Cayman Islands via migratory patterns might help give weight to the need to protect them - proving that they are not infrequent or fluke visitors not deserving of specific attention.

The Cayman News Service reported, "Despite their precarious situation, there is no law to protect sharks in Cayman waters but hopes for the species have been raised in the region following the ban on shark fishing by Belize, Mexico, St Maarten, Honduras and the Bahamas. Timothy Austin, Deputy Director of the DoE, welcomed the ban by neighbouring countries. 'This will give a boost to the health of the marine environment for the Caribbean,' he said."

Read about the sharks in the Cayman News Service.

Guy Harvey Ultimate Shark Challenge: combines research with catch-and-release event

RTSea has been a supporter of the Shark-Free Marinas Initiative (SFMI), which takes an incremental approach to re-educating sport fishermen as to the value of living sharks - as opposed to dead, trophy animals - through the use of catch-and-release techniques. While it would be great to have sport fishermen stop fishing sharks altogether, such an all-or-nothing approach would not find a receptive audience, and so the SFMI transitional strategy has found support from many participating marinas and organizations like the Humane Society of the United States.

Another SFMI supporter, the Guy Harvey Ocean Foundation, conducts a major shark fishing tournament that is not only a catch-and-release event, but also works with research organizations like the Mote Marine Laboratory. At the start of this year's Guy Harvey Ultimate Shark Challenge, a large female bull shark was tagged and it's location is being regularly tracked. This kind of data allows researchers to better understand the shark's travel/migratory behavior and what risks it is exposed to as it travels through various territorial waters - meaning various commercial shark fishing areas.

Here's is a recent update posted by SharkDivers:

Guy Harvey Ultimate Shark Challenge - Tagged Shark Moving Fast

Monday, May 10, 2010

The Guy Harvey Ultimate Shark Challenge
represents a radical change in shark tournament modeling.

Combining shark research and best shark fishing practices the ultimate goal for this tournament is to promote "change from within" the sport-caught shark fishing industry.

A recently tagged female bull shark (perhaps gravid) is now making tournament shark fishing history in Florida waters as she reports her position to Mote Marine Labs and waiting researchers.


Background

On the first day of the Guy Harvey Ultimate Shark Challenge (May 1, 2010), a large bull shark (Carcharhinus leucas) was caught by tournament competitor Bucky Dennis. This adult female was possibly pregnant and an ideal candidate for satellite tagging by Mote Marine Lab's research team. The tag was attached to the shark's first dorsal fin such that it would be able to transmit whenever the shark was at the surface of the water. These transmissions provide precise location and movement information that will contribute to our understanding of the habitat preferences of this important marine predator.

For more information and to view her daily track go here.

White Shark Tagging: controversial technique flounders in the Farallons

Controversy is now dogging the white shark tagging efforts of Dr. Michael Domeier of the Marine Conservation Science Institute. The SPOT (smart positioning or temperature) tagging began in Isla Guadalupe under the eyes of a film crew for a National Geographic Channel program to air on the 19th. It involves a technique whereby the shark is hooked and reeled on board, aerated with a water hose, while the crew literally drills and bolts a satellite transmitting tag to the shark's dorsal fin.

This is a rather elaborate tagging technique that has generated much concern within the shark conservation community (click here for prior posting about the Isla Guadalupe taggings, and here are two from other sites: click here and here).

Now, Dr. Domeier has moved northward to the Farallon Islands and, with the approval of Maria Brown, superintendent for the Gulf of the Farallones National Marine Sanctuary, has been tagging sharks there but with less than optimal success. Apparently, one shark swallowed the hook deep into its throat causing the bait's float to become lodged in the shark's jaws, thereby blocking access for the aerating water hose and requiring the cutting of the hook by working straight through the shark's gills. All in all a disaster in humane animal treatment as far as I'm concerned.

While there are concerns about the stresses this type of tagging places on the shark, there is also the question as to the need for more data acquired in the Northern California area. Dr. Barbara Block of Stanford, Dr. Pete Klimley of UC Davis, and others have amassed a considerable body of data that tracks the migratory patterns of these animals. They and their colleagues just recently issued a detailed report that can be viewed in the Proceedings of the Royal Society, published online on 11/04/09 in the Biological Sciences section ("Philopatry and migration of Pacific white sharks").

I always felt that this particular tagging technique was a more elaborate mousetrap than necessary. Now its efficacy has become controversial, the California data may ultimately be redundant, and the National Marine Sanctuary must defend a decision to allow catching a protected species in a manner that would most likely not be allowed for, say, a protected marine mammal.

Too many questions, too much controversy. . .

Read article in Bay area bohemian.com.