BlueWater Boats & Sportsfishing – July 2019

A SAILFISHGETS EATEN

Date

Depth

(mm)

Thisgraphshowsdepth and water temperature recorded by a pop-up satellite tag attached to a

sailfishoffBroomein Western Australia. This shows that the sailfish was behaving normally, diving

regularlyfromthesurface to depths of 20 to 25 metres for 21 days. However, the red arrow marks

thestartof abruptchanges in depth, and subsequent warm temperatures at depth, indicating that

thetagwasswallowed by a presumed shark. Seven days later, the shark regurgitated the tag, which

floatedto thesurface where it transmitted this information to passing satellites.

In a study by Dr Michael Musyl, 37 lure-caught

blue marlin were released with satellite tags off

Hawaii. Thirty of the tags reported, of which only

one indicated a mortality – and that occurred 82

days after release and was regarded as a natural

predation event. (Note the longline hook in the

corner of this marlin’s jaw.)

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Life after release