I remember reading it at school but do not remember if it was in a collection of short stories or a book. It was the 80's so it would be that time or before the 80's. What I remember is a new planet the ship I think crashed or had a malfunction and some how some dna got mixed up. I remember the main character watching what was either a seal hybrid or a dolphin hybrid swimming.It was mixed up with something weird that today we know would not happen. Its been over 20 years and that's about all I can remember.
Maybe a long shot, but... David Brin's "Startide Rising"? The fit:
- Written 1983
- Ship hiding on a planet for repairs.
- Dolphin crew (with some humans). Not "mixed up DNA" but "uplifted".
- Actually, I note the WP article mentions "Parts of Startide Rising were published as "The Tides of Kithrup" in the May 1981 issue of Analog." so maybe that's what you read.