This video from Britain says about itself:
The art of preserving a blue marlin | Natural History Museum [in London, England]
2 August 2017
The blue marlin is one of the Museum’s largest-ever specimens preserved whole in fluid – and an innovative technique will make this enormous fish last. Watch curators prepare the blue marlin for display.
This 2015 video is about tag and release blue marlin fishing in Panama.
From Wildlife Extra:
Blue Marlin found on Welsh beach
August 2008. Remarkably, just a few weeks after a swordfish was found on a beach in South Wales, a Blue Marlin has washed up onto another Welsh beach, this time in Pembrokeshire. While out for an early morning walk on the sands of Saundersfoot fisherman Gavin Davies saw a strange shape rolling around as the waves pushed up the beach, and on closer inspection he discovered it was a billfish. With the help of four friends and a Landrover he pulled it up the beach to where it could be examined.
Blue Marlin – First ever recorded in Wales
At this time they could see it was a marlin and contacted South Wales Sea Fisheries Committee Officer Mark Hamblin to check it out. Mark was able to determine that it was a Blue Marlin (Makaira nigricans). A fish virtually unknown in British and Irish waters and the first ever recorded from the Welsh coast. This large fish with a spear-like snout can grow up to 5 metres long and weigh over 660 kilos. The Welsh fish was 2.75 metres and weighed about 190 kg. It is not known what caused its death but the large numbers of dolphins around the area at the moment might have attacked it, but it also appears slightly emaciated indicating that it may have been unwell, or simply unable to feed in the cooler British waters. Once stranded it was attacked by scavengers that opened up its belly.
Only second UK specimen ever
Records from the UK Marine Fish Recording Scheme managed by the National Marine Aquarium in Plymouth show that this is the second Blue Marlin to be recorded from British and Irish waters and only the fourth billfish (the first in Wales). The first UK Blue Marlin was a specimen of 3.7 metres found dead on a beach on St Agnes in the Isles of Scilly in March 1982. A 1.8 metre long White Marlin was found alive but dying in Morecambe Bay in August 1983, and a Sailfish of 2.66 metres was washed up at the mouth of the River Yealm in South Devon back in August 1926.
The Billfishes found in North West Europe are:
– Sailfish Istiophorus albicans
– Blue Marlin Makaira nigricans
– White Marlin Tetrapterus albidus
– Roundscale Marlin Tetrapterus georgei
– Longbill Spearfish Tetrapterus pfluegeri
The relative bulkiness and the depth of the body of the Welsh fish, in comparison to the height of the dorsal (back) fin shows it to be a Makaira, a blue or black marlin, as opposed the more slender sailfish and white marlins. Opinion among experts varies as whether there are one, two or three species of Makaira. Hence it is difficult to distinguish between them from a photograph. The most likely one is the Blue Marlin Makaira nigricans, with an outside possibility of the Black Marlin Makaira indica.
Marlin, sailfish and spearfish are among the most magnificent creatures in the sea, but commercial fishing has driven down their populations; now a simple change in fishhooks may help save them: here.
Double jeopardy: Tuna and billfish: here.