The Marine Institute based in Galway, Ireland, conduct the Irish Groundfish Survey once a year. The aim is to monitor fish stocks around the Irish coast. I joined them on their final cruise leg, 11 days at sea in December 2016. My primary aim was to collect jellyfish samples for a Ph.D. student at the University of Southampton. The mixed species collection of jellyfish were sent for analyses to create “isoscopes”. The efficacy of using stable isotopes to track and monitor the spatial ecology of free living marine animals is being examined at Southampton.
I departed with the cruise team from Galway docks on board R.V. Celtic Explorer in calm seas. Although I have spent a lot of time at sea on day boats and conducted 10 day cruises in the Red Sea, this was to be my first sustained, offshore research cruise on a larger research vessel in temperate waters. With signing on complete, my excited anticipation grew.
Kitted up in oilskins, all biologists convened in the wet lab as we arrived at our first sampling station. Most of the staff were permanent or contracted employees from the Marine Institute. I was the only Ph.D. student but still participated in the full sampling program in return for the jellyfish samples. As a first timer, I was paired with a more experienced member of staff. The briefing was more of a learn-as-you-work approach, which suited my hands-on nature just fine.
The standardised survey method employs the use of an otter trawl net. Fishing time is thirty minutes at pre-determined GPS waypoints. The catch then arrives into the wet lab on a conveyor belt where the scientists sort the catch into species and size classes. All fish are then measured weighed. For commercially important species, sex and maturity are also recorded, and their otoliths collected. Once all the required data is collected the catch is consumed either by staff on board or by our permanent following of gulls, gannets, and dolphins.
Despite this conscientious use of the catch, it was a shock for me to see up to a tonne of marine life per haul removed from the sea. But our catches were small in comparison to commercial trawls. Additionally, scientists currently have no better quantitative method to monitor stock and set catch quotas. DNA sampling has been suggested as promising alternative. But this method is not quantitative. In addition DNA sampling cannot provide the full data required to set responsible fishing quotas such as sexual maturity and fish length.
The beauty and the challenge of being at sea
Being at sea is both tough and beautiful. Twelve-hour shifts, constantly on my feet, were made worth it when I saw the setting sun sparkle through the spray of a swelling wave or hundreds of gannets diving to retrieve our discarded fish. As is often the case on team endeavours, the people make the job memorable. I was fully supported by the staff as I acquired the new skills within the survey protocol. Even when at first that meant the job took a little longer. I was fully integrated into the team and for that I am grateful to my colleagues who have become friends.
In anticipation of the next cruise…
I was also happy to be just minimally afflicted with seasickness only on the first day. Even as a large swell picked up at the offshore stations in the final few days, I maintained my calm stomach. So, I’m eagerly anticipating my next opportunity to go to sea. Though the cruise objectives were outside my primary coral research field, time at sea is invaluable. It strengthened my connection with the ocean, provided me with new fisheries lab techniques, and reinforced valuable teamwork skills that can easily become neglected working on an independent Ph.D. project.