Saturday, January 24, 2015

Are GWS Populations in Decline?

No, "they" are absolutely not!

DNS doesn't post my comment, so there.
This is just simply wrong. It appears to principally base its assertions on the 10-year old assessment by the IUCN - but in the last ten years, things have obviously changed. 
GWS are one of the best protected species both internationally (CITES and CMS) and nationally, and those decades-old conservation measures are not useless and ineffective but instead, we have plenty of indications that they are quite obviously working.

Here's the situation as I understand it.
  • USA: populations are rebounding on both coasts following the protection of both the Sharks and their pinniped prey. Although there are only published data for California, the increased sightings on the East Coast lead to the conclusion that as a minimum, juvenile and subadult GWS now have a better chance of surviving = there will be more Sharks of a size where they will switch from a fully piscivorous to a mixed diet and become a threat to aquatic recreationists.
    This means that GWS sightings but also strikes will increase and that the authorities need to think now about preemptive measures = education of the public but also Shark-friendly mitigation measures from seasonal beach closures to spotters to exclusion nets, etc.
  • South Africa, reputedly the largest population, appears to be flat to in slight increase.
  • Mexico's population may be at risk due to incidental catches of YOY and juveniles - but nobody quite knows. In any case, the sightings in Guadalupe (= only adults) are not declining which is a reason for cautious optimism.
  • Mediterranean completely unknown - but in view of the desolate condition of all Shark populations there, prospects for the Mediterranean GWS are likely equally grim.
  • NW Pacific population (= Asia) unknown.

DNS, not impressed!

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