Did I turn the tags on?
A little over a month ago, I handed over a rather expensive kit of equipment and survival tags to a fisheries observer. I have been involved with a few tagging studies before, but this was my first experience accepting the fact that equipment purchased with my hard-earned grant money was being chucked over the side of a vessel with the high likelihood of never being seen again. Doing the maths in my head, that kit was equivalent to six years’ worth of services from Dave. Dave is my Disneyland Dad dog walker who my dogs adore more than anyone else in the world.
The survival tags were earmarked for our gulper shark (Centrophorus squamosus), one of New Zealand’s larger deepwater sharks that is caught incidentally in the commercial longline fishing fleet. Gulper sharks are amongst the most threatened group of sharks today, but we still regularly report them in New Zealand waters. The purpose of the project is to shed some light on gulper shark post-release survival after capture in New Zealand fisheries, while also gathering information on how this species uses its environment. This information can help us better understand species’ risk to threat (i.e., fishing) and, hopefully, inform and improve mitigation measures that reduce our impact on this threatened species.
It has been a bit of a juggling act getting these tags deployed. I have required the assistance and willingness of the ministry, the observer programme, the observer, and the commercial fishing vessel. The observer I’m working with is fantastic – she has been a fisheries observer for years and has been involved with previous tagging studies for pelagic fish. She knows how the fishery operates far better than I’ll ever understand, loves being out on the water, and was very keen to help.
A tagged female gulper shark (Centrophorus squamosus) ready to be released. Photo © New Zealand Ministry of Primary Industries Observer Programme
My initial plan was to deploy tags on Chatham Rise and Puysegur, the former being New Zealand’s most important fishing grounds, the latter being a suspected deepwater shark nursery area. Due to a combination of factors, these tags ended up on a vessel operating on the West Coast of the South Island (WCSI). We do not have a lot of information from WCSI. Turns out many of the gulper sharks that the observer came across on the trip were big, chunky females – an interesting initial observation.
Nine tags were deployed this trip. Three have recorded back so far; the others have remained silent. I’m hoping that is a good sign and that those sharks are happily enjoying life back down in the depths of the ocean. If everything goes to plan, those tags will pop off in about a months’ time, and report back with a wealth of information on what these sharks have been up to for the past few months. Until that day comes, I will continue to sit at my desk and ask myself, did I turn the tags on?