Marine

Mark Desmond heads out on the second Leg of the Irish Anglerfish and Megrim Survey (IAMS) 2019


With a sunny arrival into Galway harbour on the twenty fifth of March, my ten days on the second leg of the 2019 Irish Anglerfish and Megrim Survey (IAMS) on the RV Celtic Explorer got here to a profitable conclusion. As a SMART trainee, the 2 weeks had been a useful perception into how a FEAS survey is carried out, the methodology utilized in organic information restoration, and customarily getting accustomed to the fish species of the North East Atlantic.

The aim of the survey is to acquire biomass estimates for each black and white anglerfish (Lophius budegassa and L. piscatorius) and an abundance index of each megrim species (Lepidorhombus whiffiagonis and L. boscii). Secondary aims have been to acquire organic information of commercially essential species and to discover the vary of Megrim and Anglerfish into deep water beneath 1000 metres. This additionally gave me a possibility to come across and assist establish deep-sea species.

Determine 1: The species focus of this survey, anglerfish on the left and megrim on the suitable

On Wednesday the thirteenth of March the Celtic Explorer set off from Cork Harbour into the Celtic Sea on its strategy to its first station. On the way in which out a gathering to organise the scientific groups and to run via the digital  measuring system and software program was held.  Arising from this two groups of seven have been shaped and allotted shifts, one working from 04:00am to 16:00 with the opposite working from 16:00 to 04:00.

Throughout this leg, stations have been lined from the south west of Eire within the Celtic Sea as much as the northern ridge of the Porcupine Financial institution and elements of the Rockall Trough.  The primary station got here rapidly and each scientific groups processed the stations samples so as to standardise follow and convey everybody up to the mark on the methodology.

Right here I’ll roughly describe this technique as I skilled it. The contents of the trawl have been transferred to a metallic hopper adjoining to the moist lab and accessed by a shoot with a conveyor belt. The belt introduced the assorted species into the moist lab the place they have been recognized and sorted into packing containers as proven in Figures 1 and a pair of beneath.

Determine 2. The conveyor belt within the moist lab the place the catch was sorted into species

Determine 3. The catch sorted into species, one species per field

This was a fantastic alternative to be taught the diagnostic options of the assorted fish species caught as on first look some reminiscent of megrim and 4 noticed megrim proven in Determine 4 could be quite comparable.

Determine 4: Megrim (Lepidorhombus whiffiagonis) vs the 4 Noticed Megrim (L. boscii). Notice the distinction in colouration of the again fins, the place 4 spots are current in L. boscii.

Gráinne the deck grasp recorded the overall weight of every species earlier than supplying them to the scientists to file particular person organic information reminiscent of size, weight and maturity, in addition to recovering otoliths.

Data was recorded on a specialised measuring board with using barcodes and a scanning pen, every species was assigned a person code on the system, which corresponded to a proportion of otoliths required and what standardisation of size measurement was required, e.g. Complete Size, Pre-Anal Fin Size (PAFL) and so on. Weight measurements have been taken on specifically calibrated weighing scales. Nephrops norvegicus have been processed utilizing an digital callipers and related weighing scales and have been sorted into classes based mostly on maturity. Determine 4 exhibits the format of the workstations this was completed at.

Determine 5: Measuring workstation, with barcoded measuring board, scanning pen, pc for inputting information and weighing scales to the suitable. Otoliths trays have been stored protected within the metallic body.

All ray and shark species have been rapidly processed and returned to a storing tank earlier than being returned to the ocean. This was to extend fee of profitable return.
Otoliths have been recovered for future use in age estimation of fish. That is completed by figuring out summer time and winter bands within the bone. These bony calcium carbonate buildings are discovered behind the eyes of the fish and are utilized in steadiness.

Determine 6:  Black scabbard (Aphanopus carbo

Determine 7:  A number of the species caught on the survey together with clockwise from prime left Anglerfish (Lophious piscatorius), Rabbit fish (Chimaera monstrosa), hollowsnout grenadier (Coelorhynchus coelorhynchus), birdbeak dogfish (Deania calcea), Coal Fish (Pollachius virens), Redfish (Sebastes mentella) Forkbeard (Phycis blennoides) and centre, Alfonsino (Beryx decadactylus)

There have been totally different figuring out options for maturity based mostly on the kind of species being studied. It was fascinating familiarising myself with these options throughout a wide range of the industrial species. For instance, in gadoid species, mature and breeding males would have ribboned testes containing semen, which might movement below mild strain. Mature females would have two ovaries with hydrated eggs if mature. Flatfish species then again would have a big egg sack for females working alongside the size of the fish with hydrated eggs if mature. This may very well be simply noticed below a lightweight in species reminiscent of megrim. The testes can be discovered below the digestive system in the event that they have been male.

Recording organic information of anglerfish was carried out with two individuals because of the further steps concerned. Abdomen contents of the anglerfish have been stored at sure stations for future steady isotope investigation into feeding patterns of the anglerfish. Illicia of the anglerfish (their lures) have been recovered as a substitute of otoliths as a technique to age the fish.

Determine 8.  Anglerfish on digital measuring board

Determine 9. Angler fish being weighed on marine calibrated scales
Determine 10. Intercourse and maturity stage dedication of anglerfish (Lophius  piscatorius)
Determine 11. Ilicia, the anglerfish’s lure being taken for ageing.

Every station was processed as described above. As a consequence of dangerous climate on account of storm Gareth, some tows have been delayed however all major stations have been accomplished, in addition to a number of deep-water stations which resulted in some very fascinating species. Books have been consulted to establish among the much less frequent species such because the deep-water Sculpin and octopus proven in Figures 12 and 13.

Determine 12.  Deep-sea sculpin: Cottunculus thomsonii 
Determine 13. The deep-sea octopus Bathypolypus pugnige

Time on board wasn’t all work within the moist lab both. Relaxation intervals between trawls gave me the chance to interrogate the scientific employees over tea! Conversations with Chief Scientist Sara Jane Moore gave me perception into the position of a fisheries scientists working for the Fisheries Ecosystem Advisory Providers (FEAS), and the way these surveys are undertaken, in addition to their higher use in a consortium of information offered at ICES. I vastly admire the time she gave in answering my questions. Gráinne additionally confirmed among the scientific employees and me how one can obtain info from the CTD (temperature and depth probe) and the way this oceanographic info provides context and determination to the fisheries information we collected.

General participating within the 2019 IAMS was a incredible expertise and has provided an perception into fisheries science unattainable anyplace else. I’m very appreciative of John Boyd and the Strategic Marine Alliance for Analysis and Coaching’s (SMART) Coaching via Analysis Scheme (TTRS)  for enabling my participation. I might additionally wish to thank Sara and Gráinne for his or her generosity in sharing their expertise and experience and all of the scientific crew for exhibiting me the ropes and placing up with any errors I made alongside the way in which!

Widespread dolphins swimming alongside the Celtic Explorer on IAMS leg 2.

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