The black enigma

If you’ve visited a local supermarket or fish market, there is one specimen that you just cannot miss. Their large, jet black eel-like bodies, enormous gazing eyes and pointed gaping jaws with their fang-like teeth make them an instant eye-catcher. The Black-Scabbard fish (Aphanopus carbo), locally known as Espada preta, is a notorious cuisine fish here in Madeira that is served pretty much everywhere on the island. So if you haven’t seen it in the supermarket, you most definitely read it on a menu at a restaurant.

While Espada is impossible to miss on the island, it is a fish you will never ever encounter alive. These animals are most abundant at depths ranging from 800m to 1300m with adults occuring at bathypelagic depths (1000-2000m) while juvenile animals are assumed to remain at mesopelagic ranges (200m-1000m) before they mature. Their large eyes, their elongated body and their pointed head make them very agile and formidable deep-sea predators that hunt a large variety of marine organisms at different depths including crustaceans, cephalopods, and various mesopelagic fish.

As with most deep-sea creatures, little is known about the life cycle of the Black-scabbard but a common assumption is that a single stock undertakes a clockwise migration in the Northeast Atlantic during the course of its life. Juveniles tend to feed and grow near the Faroe Islands and the British Isles before migrating further south to spawning areas. The most well known spawning area is Madeira meaning that the animals frequenting the island are mainly fully-grown adults reaching lengths of up to 110cm with the oldest animal ever caught boasting an age of 14 years.

The speed and agility of the scabbard doesn’t make it an easy prey for other larger predators of the dark ocean. Beaked whales, deep-diving cetaceans, are known to hunt cephalopods but also several fish species during their deep foraging dives. Most are thought to be suction feeders and their diet is only known through markings on their bodies and stomach content analysis of deceased and stranded animals. A creature that preys on both the Black Scabbard (along with several other fish species) as well as on various cetaceans is the parasitic nematode Anisakis.

As mentioned earlier, Espada is one of the fish that is most prized for food by locals on the archipelago and has gained a stronghold in the local diet. In Madeira Espada is caught using bait attached to long-lines that extend up to 2km into the depths. Weights are attached to these fishing lines to maintain their vertical position in the water column and they are marked with flagged buoys. We often see fisherman deploying or collecting these long-lines during our tours or see black-scabbards dead at the surface. Its high market value has lead to the extensive exploitation of the species with it being fished commercially in Madeira as well as near mainland Portugal, Iceland, France, Ireland and around some areas close to the Canaries.

Recent studies, however, have shed light on the health risks involved in consuming black scabbard and other deep-sea fish. The deep ocean acts as a sink for several contaminants, particularly heavy metals which are not metabolized by organisms and therefore tend to bioaccumulate up the food chain. The presence of heavy metals, such as mercury, lead and cadmium, in the flesh of these animals have lead scientists to urge people to keep the consumption of these species in moderation and completely exclude the liver. Moreover, consuming uncooked black scabbard could lead to an infection through the previously mentioned nematode, Anisakis.

One can say that the Espada is somewhat of an enigma; it is everywhere and nowhere at the same time. We know little about the fish when its alive and encounter it on every corner when it’s dead. The common name of the animal is infact a reference to its appearance after death where the animals turn jet-black. When they’re alive these deep-sea fish are infact a coppery-black iridescent colour, occasionally gleaming in the darkness.

By Paula Thake