AFBI Groundfish Survey - Leg II

“Call me Ishmael.” Like Moby-Dick, this is half a story about my time aboard a ship and half about marine biology. Unlike Moby-Dick, the ship in this story doesn’t sink and there are no insane captains!

Like Claire the previous week, I joined scientists from AFBI aboard the institute’s research vessel 'Corystes' for the October Groundfish survey. Eager followers of the LivingSeas Blog will know that Claire was aboard for the first leg of the survey and we would be swapping places for the second leg.
In the days leading up to my departure, I had only a vague idea of when (and even where!) I was going to be heading out. “It’ll be a day either side of October the 11th, possibly two. And it might be in Dublin. Or maybe Belfast. Probably Dublin” I was told.

The 11th was a Wednesday and since I hadn’t heard anything at the weekend, I decided to pack on Monday evening after work. This was a good plan because I got a text from Claire on Monday morning; “We’re docking this afternoon in Dublin – you need to be on the boat tomorrow evening at the latest. Bring good waterproofs and I hope you don’t mind getting stinky because you’ll be handling A LOT of fish. Enjoy!”

Patrick tagging a tope

So now I had a time and a date, I just had to get myself to Dublin and I was all set! As I was searching train times to Dublin I was put in contact with a member of staff at AFBI who would be heading down to Dublin the next day to join the boat, just like I was. Josie (coincidentally an old friend of Clare’s) let me know that a car would be travelling from AFBI HQ in Belfast and there was a space for me. Perfect! Everything was organised, I just needed a packed bag and I was ready for the high seas.

I arrived at AFBI HQ in good time the next day, hopped in the car and was on my way! We arrived in Dublin 2 hours later, and in another 20 minutes we had parked beside the Corystes, berthed on the Liffey. I was directed down into the bowels of the ship to find my cabin. I was pleasantly surprised by the relative luxury of the room; in addition to a comfy bed, I had a sofa, desk and chair, wardrobe and drawers, a sink for brushing my teeth and, whilst it was no en suite, I was right beside the shower/toilet (sometimes called a “head”).

Everything a marine scientist could possibly need! I unpacked quickly and went to explore. The AFBI staff I had travelled with were eager to join their colleagues who were out enjoying Dublin culture on the mid-cruise break (and probably enjoying a pint of a certain drink beginning with “G”...). I was invited along and I met lots of the crew, but I returned to the ship early; I wanted a good night’s sleep (and a clear head in the morning) before getting up for my first day on the sea.

Haul of jellyfish

I got up at 7am for what I thought was an early breakfast at 7.30. A cooked breakfast of sausage and bacon; I could get used to this! We were due to depart Dublin at 10am so I got an induction to the ship in the mean time. Come 10, we sailed out, holding up half of Dublin on their morning commute as the East-Link Bridge was raised to allow our passage out to sea!

We were soon steaming towards our first station and I was raring to go. We were in the southern Irish Sea and the weather was good; windy, with a big swell but I had taken my motion sickness tablets and I felt great!

The first trawl pulled up dozens of lesser-spotted dogfish and hundreds of other marine organisms. Like Claire before me, my first task was to tag the sharks brought up in the trawl. The sheer number of dogfish caught meant that it was impossible to tag every single one, so the protocol was to take the details of and tag five individuals. The details include species (easy in this case as they were all the same), sex, length and sometimes weight. Measuring the weight on a busy research cruise like this sometimes wasn’t possible, especially for the smaller animals like dogfish, so it was only a priority for the larger species like nursehounds and tope. Finally the tag number was recorded so in the future, if they are re-captured, we know which animal is which! The same information was recorded for skate and ray species, except their wingspan was measured instead of length. After all this was done the animals were returned as quickly as possible to the sea, to reduce stress and ensure the best possibility of survival.

Corystes deck silouette

Once I was done with my elasmobranchs, I moved in to work with the AFBI scientists in sorting the rest of the catch. Some species were easy to distinguish; squid look very different to mackerel. Some species were a little harder; plaice look similar to dab, both are flatfish, but if you know that dab have a rough surface you can easily tell the difference before you can tell them apart by sight. Then there were the two species that I found almost impossible to tell apart; herring and sprat. Herring grow much larger than sprat can (45cm vs 16cm), so older herring were easy to tell apart but younger individuals look almost exactly the same.

Both species belong to the Clupeidae family of fish and are physically very similar. I was informed that by the end of the trip I’d be an expert at clupeid ID, and was assured that there was indeed a difference between the species, although these differences are slight. Herring have a rough belly that can be felt when rubbed, but the belly of a sprat is so rough that it feels like a serrated knife. The colour of a herring’s back is a greenish-blue, while a sprat’s back is more of a bluish-green... Another way to distinguish species is to look at the dorsal fin. In herring the start of the dorsal fin should “clearly” be in front of the start of the pelvic fin. In sprat it should fall in line or behind the pelvic fin. Not always easy and definitely made harder when you’re on a busy ship heaving about in the swell and you have thousands of fish to sort!

After the fish were all sorted into species, and size classes for commercially important species like herring or whiting, length frequencies and weight distributions were taken. This information, when collected over different areas, allows analyses to be performed that show the status of a fish stock. By sampling and recording at 62 sites in the Irish Sea, AFBI can infer how healthy the populations of these fish are. By performing these surveys at the same 62 sites, twice a year each year over many years, changes in fish populations can be tracked and monitored. This data is used to produce a stock assessment which informs DAERA and is reported to ICES (International Council for the Exploration of the Seas) and the European Commission.

Life on board continued like this for the first week; doing between five and seven trawls a day, then tagging, sorting and recording the catch. I got a lot of tagging and hands on experience with the sharks and rays with 126 animals tagged! I tagged 9 different species; lesser-spotted dog fish, bigger nursehounds (or greater-spotted dog fish), spurdogs, smooth-hounds and starry smooth-hounds, a couple of big tope, thornback rays, spotted rays and blonde rays. Hopefully the information I recorded proves valuable and some of my tagged sharks are re-captured!


I also saw a huge number of species I had never seen in the wild before. Some were familiar from the fish counter in the shop, like the edible squid, referred to by its scientific name Loligo, and monkfish, a fish that’s all mouth and not much else. It will try to eat just about anything that fits (pictured trying to gobble a dogfish AND a whiting)! Others, like the cloak anemone were completely new to me! This anemone, with beautiful purple spots, lives in symbiosis with a hermit crab host. The anemone feeds on food that the crab collects and, if the crab feels threatened, spreads its poisonous tentacles for defence. The crab signals to the anemone by shaking its body within the seashell it lives in.

We had a string of very successful days with only two stations left in the North end of the Irish Sea, but on Sunday evening at the end of my first week conversation turned to an infamous lady who was on her way to ruin our good fortune. Ophelia. Ex-Hurricane Ophelia. Yep, we were in the middle of the Irish Sea, not far from the Isle of Man, when severe weather warnings were issued in the UK and Ireland. The plan was to hit one more station early on Monday morning, and then it would be full steam ahead for the safety and shelter of Belfast Lough. We arrived in the early afternoon, just as winds were picking up. We anchored off Bangor. So near yet so far from home! The winds were so ferocious that it was safer to remain at sea than to try and tie up at a harbour! Here we stayed for the duration of the storm. Despite the bad weather (and my mother’s worry!), I was very comfortable. The boat’s nose was pointed into the wind and apart from the howling noise (winds of up to 70mph were recorded at Orlock point) there wasn’t much more movement than when we were at sea.

As the storm subsided about 24 hours later, we headed back out to work on Tuesday afternoon to survey that final station! We arrived before dark and were done sorting it by half 8 in the evening. We headed back towards Belfast overnight and tied up just after 10am on Wednesday the 18th.

After eight days of hard work (17 for the crew that didn’t swap at the mid-point break) we had finished two days ahead of schedule and surveyed 61 out of 62 stations, only missing one at the very southern point of the Irish Sea. I thoroughly enjoyed my time aboard, contributing to the science being done in fisheries management in the waters around our coast, not to mention trialling a brand new and really exciting shark-tagging project!

My thanks go to AFBI, because without them I wouldn’t have got the opportunity to go out, and to the scientific staff and crew, who made my time aboard fun, educational and the highlight of my year as a trainee!