I think it’s fair to say that finding a large dead fish washed up on a lovely walk across the beach is not everyone’s idea of a great day out… however whether fresh and slightly sad or degraded and frankly disgusting, a dead sunfish slowly rotting away has the unbelievable ability to enhance my day. As a conservation biologist, I have never killed a sunfish for research purposes; however there is a treasure trove of information that can be collected from examining a dead fish, from deep tissue samples for isotopic analysis of diet, to extracting vertebrae for age analysis, there is so much still to learn about these fascinating fish! Alongside cutting edge analyses of tissues, examining a carcass also provides an unparalleled opportunity to learn about fish morphology from old fashioned dissection and exploration.
Throughout my PhD I have been seeking to collect as many stranded sunfish as possible but these are relatively few and far between. I was provided with one large individual from Lough Foyle, Northern Ireland that was kindly collected by the Lough’s Agency in 2015 (so-called ‘Murray the mola’) and last year we spotted photos on Twitter of a small specimen that had washed up in Kimmeridge Bay in Dorset, England. Luckily ‘Kim’ was found by marine biologist Julie Hatcher who kindly held on to it until I could arrange a lift to transport the fish to my parents’ house, where it lived in their home freezer for a few days until I brought it back to Belfast boxed up as my hold luggage (bit of a weird one to explain at Customs!) Following these collections I needed to organise a formal dissection, an event which transformed into one of the highlights of my PhD to date. Although I had tried my hand at dissections at school and during my undergrad degree, I had never been particularly confident in identifying one squishy blood-stained tissue from another squishy stained tissue and I struggled to get past the ick-factor, which as a wanna-be biologist left me feeling disheartened (not to mention a bit queasy!) Luckily, with a few tips and tricks on dealing with appalling smells (vapour rub under the nose works a treat) and an ever-increasing enthusiasm to learn more, I’ve been waiting for a chance to try again.
Photos: Top left, Murray the Mola; Top right Murray wrapped up in the car to Belfast; Middle left Julie Hatcher and Kim sunfish; Central row Kim’s journal from freezer to boxing to Belfast!
In Italy last year I posted a short blog about a small dead sunfish caught accidentally as bycatch in the local fishery which I carried home on the train in a shopping bag and dissected over the bidet in my rented apartment. Thanks to its strange dinner-plate shape, the ocean sunfish’s internal organs are beautifully laid out and navigation of differing organs is made simple by vivid colours which I had never noticed in undergrad classes when working on greyish farmed trout. Beneath the thick skin and muscle layers, the sunfish gall bladder is bright green, the liver a faded mustardy yellow and the heart of course a deep dark red.
After this brief exploration of sunfish anatomy, I was really looking forward to learning more about the intricacies of dissections with our larger specimen in Belfast. This experience was further augmented by the opportunity to work alongside Prof John Davenport (something of a legend in the anatomy world). The last full dissection of an ocean sunfish was published in the 1920’s so it was fascinating to pull together all the notes we could find on their internal structure (which turned out to provide a rather limited reference library) and get stuck in!
We spent 4 days slowly working over Murray Mola from nose tip to tail exploring every tiny detail that struck us as interesting (for more info watch this space)! The whole dissection process was fascinating and incredibly valuable, from learning about internal structuring to collecting further samples for my PhD research and we all were struck with how much could be gained from a single specimen.
Photos: Above left, Whistling on the train *no sunfish dripping here…; Above right, sunfish dissection in 33 degree heat in the apartment bathroom.
It is always a sad sight when a stranding occurs, but thanks to the wonderful people who patrol the beaches and report their sightings, we can make the most of every opportunity to learn more about these incredible fish. If you spot a stranded sunfish we would love to hear about it! Please contact me using the comments section below or email me at: firstname.lastname@example.org or tweet @sunfishresearch