How do we take an inventory of the vast depths and expanse of the Ocean?

When most people think of the ocean it seems too big to comprehend. We once believed that our smallness by comparison meant that our actions could never harm it in any way. The fact that the Marine environment is not easily accessible, means that it is a world that seems alien, surreal and distant to the wider public. Marine citizen scientists can bridge that distance with knowledge and enthusiasm. My personal experience working in the diving industry was that scuba diving enthusiasts come from all walks of life, excitement from learning, identification and record contributions are infectious to their friends and family. All have in common a superpower, breathing underwater (periodically at least) and a deep love for the ocean and its inhabitants.


Citizen science diver surveying an eel grass bed

Public scientific contributions give communities a chance to actively participate in protection and monitoring of their local environments. There have been numerous successful citizen science initiatives in Ireland, for example: Irish butterfly and bumblebee monitoring schemes and several schemes run by Bird Watch Ireland (Donnelly et al,2013). These initiatives benefit from plenty of volunteers due to easier access, smartphone apps and other automatic data management assists. In the marine environment a smartphone won’t last, you need a smart diver which is where Seasearch Ireland and its members come in.

Citizen Science data has been shown by studies to have the potential to benefit both ecological and biodiversity studies and contribute to monitoring programs as well as help in invasive species management (via early detection) (Delaney et al,2007), and identification of new Marine Protected Areas (MPAs). Donnelly et al,2013 found the potential within schemes such as Seasearches Adopt a dive site program, to address major constraints in the continuous monitoring in subtidal areas of interest. The main ones being time, finance and availability of experts. Many studies such as that of Delaney et al,2007 compared accuracy of trained volunteers versus specialists and found it to be comparable.

Continual surveys create experts who will hone and improve their skills each time, training provided and identification guides which are continually improved upon, all add power to the data. Availability of data, data validation techniques, and survey design methods are all details which are important to any scientist using the data (Burgess et al,2016), if the survey is to be carried out again, for example, to prove a change has occurred in the environment it must be carried out the same way for comparison. Measures of variability must be assessed, and final statistics are always delivered with a probability of error and an expected range for results of a repeat survey/experiment.

None of this of course is any fun at all, well not for me anyway, statistics was my worst module, a necessary evil. Preliminary assessment of the responses I have had with the quiz suggest extremely responsible recording and a high level of knowledge. This week I will be writing the final report and holding off on the statistics in the hope for a few more responses. Please look out for the final report, hope to see you all underwater sometime soon,

Lisa Nihill.


Burgess, H. K., DeBey, L. B., Froehlich, H. E., Schmidt, N., Theobald, E. J., Ettinger, A. K., … Parrish, J. K. (2017).” The science of citizen science: Exploring barriers to use as a primary research tool”. Biological Conservation, 208, 113–120. doi: 10.1016/j.biocon.2016.05.014. Available at: (accessed 16/04/2020)

Delaney, D. G., Sperling, C. D., Adams, C. S., & Leung, B. (2007). “Marine invasive species: validation of citizen science and implications for national monitoring networks”. Biological Invasions, 10(1), 117–128. doi:10.1007/s10530-007-9114-0. Available at: (accessed 17/04/2020)

Donnelly, A., Crowe, O., Regan, E., Begley, S., & Caffarra, A. (2013). “The role of citizen science in monitoring biodiversity in Ireland”. International Journal of Biometeorology, 58(6), 1237–1249. doi:10.1007/s00484-013-0717-0. Available at: (accessed 19/04/2020)

Who cares about the dragonets?

Diving is so calming, everything slows down and you are acutely aware of your breathing rhythms, it’s like a meditation. In the short time (too short) spent on a dive you could spot anything from 10-100 different species depending on the site, your knowledge and the patience of your dive buddy. I appreciated the beauty and elegance of it all without thinking of the functional roles each organism plays in the ecosystem.

When it comes to conservation, often scientists will try to assign a monetary value to things in order to ensure funding for studies and protection. For example, the identification of cold-water coral habitats as essential breeding ground for the Norwegian Redfish, which is of commercial importance. There is little profit to made from Dragonets which is reflected in the lack of target specific surveys. Dr Pauline King noted an absence in C. reticulatus during her sampling in Galway bay (King et al,1978). A paper written by Chang,1951 did find specimens of C. reticulatus while sampling off Plymouth for C. lyra and added it as a North Sea fish. At that time an examination of zoological museum specimens at Bergan revealed two Reticulated dragonets which had been misidentified as the Spotted dragonet (C. maculatus, Rafinsque,1810). A review of the world’s genera by Fricke, 1981, Nekado, 1982 has led to dead specimens at least being clearly distinguishable by number of fin rays and pre-opercular spines, 1st dorsal fin and pattern differences on 2nd dorsal fin (Froiland,1976).

Close-up of 2nd dorsal fin C. lyra. WoRMS,2019.

Reticulated 2nd dorsal pattern. Hans Hillewaerte,2007.







So, the Spotted confused with the Reticulated, and the Reticulated confused with the Common. Last week we were talking about habitat preference, many of the photographs of the Reticulated do appear to be on coarse substrate noted by Seasearch members also. Fricke, 2017 sampled the Mediterranean in search of C. reticulatus and noted a preference to coarse sand bottom with large shell fragments, it was believed that the grain size was similar in size to the spots on the back and sides. During this sampling a clear depth boundary was noted between the spotted and the Reticulated with the Spotted found in deeper water. Given that the Common and the Reticulated share the same food preferences (small crustaceans, gastropods, polychaete worms & small starfish) (McDermott et al,1995) it would make sense for them to have distinguished foraging grounds also to avoid competition.

Chang,1951 found C. reticulatus rare in offshore waters where as Boer,1971 found their numbers increased further away from the Dutch coast, these varied depth findings could simply be down to substrate type at different sampling locations. Then they could easily be found both at the same site but on different substrate patches. Their behaviour could also be different in different locations, breeding time is different in the North Sea versus the Mediterranean for example, and dominant prey items vary with location. A paper was published by Burgeot et al, 1993 identifying Callionymus lyra as a target species to assess pollution in the Marine environment using biomarkers, however despite its abundance its biology was not well studied, and this is an important condition. Hopefully future comprehensive studies can be performed here to characterize our Dragonets.


  • Boer, P.,1971. “The occurrence of Callionymus reticulatus in the Southern North Sea” ICES journal of Marine Science (33(3) pp506-509). Available at: (accessed 08 April 2020)
  • Chang, H-W., 1951. “Age and growth of Callionymus lyra”. Journal of Marine Biology Association. Pp281-295. Available at: DOI: 10.3750/AIEP/02098 (accessed 22 March 2020)
  • Fricke, R. & Ordines, F. “First record of the Reticulated Dragonet Callionymus reticulatus from the Balereac Islands, Western Mediterranean”. Acta Ichthyol. Piscat (47(2) pp163-171). Available at: https:/DOI: 10.3750/AIEP/02098 (accessed 22 March 2020)
  • Froiland, O & Greve, L., 1976. “Callionymus reticulatus (Pisces, Callionymidae) from Western Norway”. Sarsia (62(1) pp1-4) Available at: (accessed 02 April 2020)
  • King, P.A., Fives, J. M. & McGrath, D. “Reproduction growth and feeding of the dragonet, Callionymus lyra (Teleostei: Callionomidae), in Galway Bay, Ireland” (1994). Journal of the Marine Biological association of the United Kingdom, (volume 74, 3, pp 513-526). Available at: (accessed 17 February, 2020).
  • McDermott, S. & Fives, JM. “The diet of an assemblage of small demersal fish in the western Irish Sea”. Biology and Environment: Proceeding of the Royal Irish Academy, 1995. (95B (3) pp195-201). Available at: (accessed 10 April 2020)
  • Wheeler, A.,1961. “Callionymus reticulatus as a North Sea fish” Annals and magazine of Natural History (4(48) pp753-754) Available at: (accessed 20 March 2020)
  • Wheeler, A. (1969). The Fishes of the British Isles and North-West Europe. Michigan state University Press, East Lansing, 1969.

Does the reticulated dragonet prefer the rocks or the sand?

A tale of two fishes

Lisa Nihill

Learning is often like going down the rabbit hole, each piece of acquired knowledge leads to more questions and sends you off down a different tunnel. I’m now itching to get back in the ocean and pay a bit more attention to these guys who become more interesting all the time.

This week I have been sending out a photographic identification quiz containing 20 photographs of both the Common and the Reticulated dragonets. The idea behind the quiz is to get an idea of an overall % error and to compare the data for identification of males versus females/juvenile males. As a biologist I fully acknowledge that photographic identification is not ideal, and certainly some of the photographs will reflect real conditions under which live recordings would be made (although you do get more time).

The development of the quiz has not been without difficulties. The initial plan was to have a bank of 100 photographs in a bank and randomly choose from this bank ensuring a balance. I had intended to obtain photographs from both the aquarium and the field, but these plans were curtailed by our collective current circumstances. This left me searching the internet for pictures where I found many which I believed to be labelled incorrectly. In fact, finding photographs which were of reputable sources was possible, but limited my bank down to a less desirable 30. Here again highlights, and possibly contributes to identification issues. With the females and the juveniles, I honestly can’t tell myself and had to double check, one was subsequently removed from the bank. Here is an example of one which I think may be mislabelled, what do you think? Common or reticulated? Can you find more?

Dragonet? Frijsinger, A & Vestjens, 2004

All Seasearch members have been doing exceptionally well in the quiz so far and many have diligently pointed out to me that many times they would like a genus option, where I have provided only species choices. This is very encouraging and of course would be the correct thing to do if unsure, and unsurety is sure to happen with some of these, I ask for people to give it a go in the interest of statistically highlighting the difficulties in identification of females and juveniles.

There has been some interesting feedback on habitat preferences too with some saying that the reticulated dragonet prefers hanging out on rocky mixed ground, where trawlers do not go and therefore divers gravitate towards. There are some who say they are found in sandy, muddy areas and some who say they are mostly on mixed gravel and coarse sand. This poses another interesting question and I plan to pull the reticulated records to determine if there is a clear pattern to substrate preference.

Until next time, I appreciate any and all participation, and wait in anticipation for your insights.

If you’d like to take part in the quiz you can download the pdf here and simply answer and email to

Where is the Reticulated dragonet hiding? Is it in plain sight?

A tale of two fishes – Lisa Nihill, GMIT

Where is the Reticulated dragonet hiding? Is it in plain sight?

I learned to dive in the subtropics while travelling and got my Divemaster in the Andaman Islands. Having come from Dublin suburbia I was ignorant of the majestic beauty of our own oceans until I returned. I feel that the term “Divemaster” was not entirely deserved by me until I had completed my first season here. Wild swells, tidal currents of 6knots, wind, cold. All these tough conditions contribute to the high productivity supporting a diverse array of life here. When the dust settles and the visibility is good there is a world of colour which rivals coral reefs, and like our sunsets are never the same from day to day.

When identification comes down to small details in the field a combination of these conditions can really make life difficult. We are in their world, and we are certainly not as prepared for it as they are no matter how much gear is dangling off us. They are often very well camouflaged in their environment, you need to “get your eye in”. Still there are organisms I don’t see until they move (been inked before you’ve seen the cuttlefish?). Particularly when the viz is like this,

 Diver in poor visibility, turbid water. (Nguyen et al,2019)

another day you get this,

Me at Gurrig Island, Maharees. (Sarah Tallon, 2013)

Bottom dwelling (benthic) organisms like the dragonets are designed to go unseen. They cruise around on the bottom feeding on small crustaceans and worms, even starfish have been found in their stomachs. They in turn have been found in the stomachs of bigger fish including cod. The ICES fish stomach contents survey returns an incidence ratio of Callionymus lyra 10:1 Callionymus reticulatus. This ratio is closer to Seasearch data (7:1) and MarLiN Marine Survey data (professional) (7:1), interesting that these are so different to records from commercial surveys. Searching through papers for comprehensive surveys of dragonets I came across a paper written by Dr Paulin King, a study on C. lyra in Galway Bay, and as luck would have it one of my favourite lecturers. During the following interview we talked about C. reticulatus and I asked had she come across many of them during sampling, she said she had not (King et al, 1994).

This got me thinking again about their differences, back to the drawing board so to speak. Size could be an important factor here, the Common is the larger of the two max length male 30cm, Female 20cm. Pauline collected her samples from bycatch piles on Nephrops trawlers mostly in Galway Bay, the cod end would have a mesh size of about 80mm diamond mesh, although this size is being reviewed. In her paper she mentions the diversity amongst the destructive piles. I wonder now if the smaller size of the Reticulated makes it less susceptible to the trawl. Pauline found among her samples a significant deviation from 1:1, M: F, there were more males in the samples, and it was suggested this could be because of the difference in size between sexes. The Reticulated Male max. length is 11cm, Female 6.5cm. Could this be the reason? Let me know what you think?


A tale of two fishes

Guiding divers in Dingle we always took an interest in identifying the species that we had seen, we had a few guidebooks including the British Marine Life ID guide. One of our most accessible dive sites has been known by many names over the years including “The gravelly” and “Thornback alley”, it is a shallow dive within the bay which is home to great diversity. The Eastern part of the site is characterised by a sandy, muddy and gravelly substrate teeming with life barely visible until disturbance sends them darting in all directions, and it was here that I first identified a Common dragonet, Callionymus lyra Linnaeus, 1758, or was it?

Fast-forward 10 years to the third year of a Freshwater and Marine Biology degree, and it is only now that I have discovered the presence of another member of the genus in our waters. I may even have already observed it without realising. So why was the Callionymus reticulatus left out of the guidebooks for so long.

Well, they are tricky little fishes. In fact, Linnaeus when first describing the Callionymus lyra in 1758 believed that the female was a distinct species. The Reticulated dragonet was not described until 1837 by Valenciennes (Darwin, 1871). They are a truly beautiful fish with males particularly well deserving of the name dragonet, the striking colours, flattened triangular shaped head and pectoral fins which when fanned out could resemble wings, the elongated tail and striking dorsal fins.

Identification features described in those dichotomous scientific identification guides containing both species often come down to things like the shape/direction of the pre-opercular spines for example, or measurement references for the relative length of the head. These are not useful ID features for the field observer of course whose subjects are not dead, hopefully. Other identification features such as the observation of the erect first dorsal fin in the male if seen, is a definitive species ID feature. The distinguished saddle markings on the reticulatus which can be seen in Image 2 can also be used. The females and juvenile males are trickier to tell apart by eye.

This project aims to investigate the distribution of both species using all obtainable records and try to determine whether the Reticulated dragonet is rare or overlooked. The data is limited, and I will need all the help I can get, I plan to interview experts in the field, analyse all the existing data, and develop a photographic quiz. I will be asking Seasearch Ireland members for participation. Any photos or stories you would like to share please contact me at The Seasearch data will be of deep interest to me given the added details of habitat and substrate type. I will be updating the blog weekly and will share all my discoveries and queries, all suggestions, advice and/participation will be gratefully received.

Until next time, wishing I was underwater with you all, Lisa Nihill.


Darwin, Charles. The Descent of Man: And Selection in Relation to Sex. London: J. Murray, 1871.

World Register of Marine Species. (WoRMS, 2019)