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 knowledge restoration, and usually 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 targets had been to acquire organic knowledge of commercially necessary species and to discover the vary of Megrim and Anglerfish into deep water under 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 technique 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 had been fashioned 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 had 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 shortly and each scientific groups processed the stations samples with a view to standardise apply and produce everybody in control on the methodology.
Right here I’ll roughly describe this technique as I skilled it. The contents of the trawl had 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 had been recognized and sorted into containers as proven in Figures 1 and a pair of under.
|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 an excellent alternative to be taught the diagnostic options of the assorted fish species caught as on first look some resembling megrim and 4 noticed megrim proven in Determine 4 might be slightly related.
|Determine 4: Megrim (Lepidorhombus whiffiagonis) vs the 4 Noticed Megrim (L. boscii). Be aware the distinction in colouration of the again fins, the place 4 spots are current in L. boscii.|
Gráinne the deck grasp recorded the whole weight of every species earlier than supplying them to the scientists to document particular person organic knowledge resembling size, weight and maturity, in addition to recovering otoliths.
Data was recorded on a specialised measuring board with the usage of 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 had been taken on specifically calibrated weighing scales. Nephrops norvegicus had been processed utilizing an digital callipers and linked weighing scales and had 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 knowledge and weighing scales to the suitable. Otoliths trays had been stored secure within the metallic body.|
All ray and shark species had been shortly processed and returned to a storing tank earlier than being returned to the ocean. This was to extend price of profitable return.
Otoliths had been recovered for future use in age estimation of fish. That is completed by figuring out summer season 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)|
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 business species. For instance, in gadoid species, mature and breeding males would have ribboned testes containing semen, which might circulate below gentle strain. Mature females would have two ovaries with hydrated eggs if mature. Flatfish species alternatively would have a big egg sack for females operating alongside the size of the fish with hydrated eggs if mature. This might be simply noticed below a lightweight in species resembling megrim. The testes can be discovered below the digestive system in the event that they had been male.
Recording organic knowledge of anglerfish was carried out with two individuals because of the additional steps concerned. Abdomen contents of the anglerfish had been stored at sure stations for future secure isotope investigation into feeding patterns of the anglerfish. Illicia of the anglerfish (their lures) had been recovered as an alternative 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 willpower of anglerfish (Lophius piscatorius)|
|Determine 11. Ilicia, the anglerfish’s lure being taken for ageing.|
Every station was processed as described above. Attributable to dangerous climate on account of storm Gareth, some tows had been delayed however all main stations had been accomplished, in addition to just a few deep-water stations which resulted in some very fascinating species. Books had been consulted to establish a few of the much less widespread 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 durations between trawls gave me the chance to interrogate the scientific workers over tea! Conversations with Chief Scientist Sara Jane Moore gave me perception into the function of a fisheries scientists working for the Fisheries Ecosystem Advisory Companies (FEAS), and the way these surveys are undertaken, in addition to their higher use in a consortium of information offered at ICES. I tremendously recognize the time she gave in answering my questions. Gráinne additionally confirmed a few of the scientific workers and me the right way to obtain info from the CTD (temperature and depth probe) and the way this oceanographic info provides context and backbone to the fisheries knowledge we collected.
General collaborating within the 2019 IAMS was a improbable expertise and has equipped an perception into fisheries science unattainable wherever 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 prefer to thank Sara and Gráinne for his or her generosity in sharing their expertise and experience and all of the scientific staff for displaying me the ropes and placing up with any errors I made alongside the way in which!