The meaning of "designar" we are dealing with is this one:
- tr. Denominar, indicar
I agree that the phrase "...designar a un lugar..." is wrong. "designar a ese delicioso pez noruego e islandés" may be accepted on the basis of this rule stated at the very beginning of Source 1 below:
[...] lo habitual es que el CD lleve la preposición "a" cuando su referente es específico y animado:
No encuentro a mi gato. [negritas mías]
"ese delicioso pez..." is, as a matter of fact, specified and animate.
Here are two sources (the first one largely based on the second one) that provide some useful rules:
Now, for some reason I can't quite define, verbs like "designar", "denominar" or "nombrar" (all synonyms) do not sound as bad, if followed by "a" plus an inanimate object, as do other verbs like "indicar". One possible explanation might be that those three verbs sound very much like "referirse a" or "asignar un nombre o denominación a". Another might be that those verbs usually take a direct object (DO) AND an object complement (OC), and the presence of two complements may render "a" more acceptable or even justified as a means to differentiate the DO (preceded by "a") from the OC. This acceptability of "a" even extends to structures like "nombre con que se denomina a ...", even if what follows is an inanimate object.
Here are some examples which, even if wrong according to strict grammar rules, do not sound so terrible to my native ears. In fact, I've taken them from Google books:
- La expedición nombró a ese lugar Puerto del Castigo... (Source)
- ... denominaron a este estilo de liderazgo como maquiavelismo. (Source)
- ... designa a ese fenómeno como "Derecho Trasnacional" ... (See line 5, paragraph 2, of the footnote here)