I live very near a small fresh water estuary salmon hatchery, and this month, the salmon are swimming upstream to spawn. They are stunning; gorgeous silver, and pink and green, and much larger than I’d expected; many are well over a foot in size. And they have come for miles, upstream, over rapids and falls to arrive at their hatchery, where they jump over a series of fish ladders, to remain and spawn (and then die), or in some cases to continue upstream to a different estuary, or even out to sea. With the value they offer as food items, and the seasonal aspect of the salmon spawn, the return of the salmon every year had to have been a fairly momentous occasion to the ancient Celts. The salmon’s ability to remember, and navigate to its own birth place to spawn suggests wisdom as well. You’ll also notice that words for salmon (eó, eú, éicne in Irish, eog in Welsh) are parts of a number names, for both people and places. The place name Leixlip, in County Kildare along the river Liffey is derived from the Norse of the Viking settlers who traveled up the Liffey, and settled; in Old Norse Leixlip is leax hlaup or “salmon leap,” a name that is likely a reference to the annual return of the salmon from the Atlantic to swip up the Liffey to spawn.
It’s worth noting that salmon are important iconographically, even for the ancient Gauls. One relief on a Gaulish altar shows a human head between two very large salmon; another altar, this time Gallo-Roman, depicts a strikingly-salmon looking fish talking into the ear of a human head. In Britain, at the temple at Lydney Park above the Severn estuary dedicated to the god Nodons, the god is shown seated, fishing, with a salmon on his line. Nodons, or Nudd, is linguistically related to the Irish deity Nuadu, and to the Welsh mythological figure Lludd Llaw Ereint.
That drive to return to where they were born in order to spawn, has helped the salmon take a special place in Celtic myth. Salmon are frequently otherworldly animals; their spots are one of the markers of such creatures. associated with wisdom, not only because of its age, and the spots that marked it as an otherworldly animal, but because salmon eat the hazelnuts of the nine hazels of wisdom, one of which grows at the heads of each of the seven primary rivers of Ireland, one at Connla’s Well, and one at the Well of Segais. Salmon are said to bear a spot for each hazelnut they have consumed.
In Irish tradition, salmon are ultimately responsible for the preternatural knowledge of Fionn Mac Cumhaill. In one version of the myth, the fili Finnécces has been trying to catch Fintan, the ancient salmon of knowledge that lived at the base of the Boyne. He finally managed to catch the salmon and is cooking the fish prior to consuming it. Along comes the youthful Fionn Mac Cumhaill, and, having touched the salmon on the fire, and burned his thumb, Fionn stuck it in his mouth—thus gaining the otherworldly oracular wisdom Finn had intended for himself. From that point on, Fionn merely sucks his thumb, and gains the answer to any question.
In Welsh myth, in the tale of Culwch ac Olwen, the salmon Lyn Llyw in the Severn, is the oldest of all living creatures, and one of the forty wisest animals. It is Lyn Llyw who tells the hero Culwch where Mabon is held prisoner, the ultimate task Culwch must perform in order to win Olwn from her father. There are numerous stories of humans who shape-shift to salmon form, including Taliesin, and Amairgin, and Tuan mac Cairill, who is caught and eaten by a woman while he is in salmon-shape, who then bears him so that he is reborn as a human. Loki in Norse myth shape-shifts to a salmon in order to hide.