Here is a long list of places where "Nerves" was published, although the only possibilities are those published in or before the 1970s.
https://www.isfdb.org/cgi-bin/title.cgi?46545[1]
Here is a long list of places where "Who Goes There?" was published, although the only possibilities are those published in or before the 1970s.
https://www.isfdb.org/cgi-bin/title.cgi?860248[1]
Here is a long list of places where "Specialist" was published, although the only possibilities are those published in or before the 1970s.
https://www.isfdb.org/cgi-bin/title.cgi?45711[2]
Here is a long list of places where "The father-Thing" was published, although the only possibilities are those published in or before the 1970s.
https://www.isfdb.org/cgi-bin/title.cgi?41412[3]
Since you remember it has a hard cover anthology with stories by different authors, the search should be restricted to multi author anthologies with hard covers published before 1980.
The only English language anthology that fits those specifications and includes "The Father-Thing" and another story you mentioned - "Specialist" - is Science Fiction: Contemporary Mythology: The SFWA-SFRA Anthology 1978.
https://www.isfdb.org/cgi-bin/pl.cgi?29199[4]
The only English language anthology that fits those specifications and includes "Specialist" and another story you mentioned - "The Father-Thing" - is Science Fiction: Contemporary Mythology: The SFWA-SFRA Anthology 1978.
https://www.isfdb.org/cgi-bin/pl.cgi?29199[4]
"Who Goes There?" is with "Nerves" in The Science Fiction Hall of Fame, Volume Two A: The Greatest Science Fiction Novellas of All Time Chosen by the Science Fiction Writres of America 1973.
https://www.isfdb.org/cgi-bin/pl.cgi?29110[5]
"Who Goes There?" and "Nerves" are also in Adventures in Time and Space 1946.
https://www.isfdb.org/cgi-bin/pl.cgi?438841[6]
If you are certain that the book you remember was an English language hard cover anthology lost in the 1980s, and that "Who Goes There?" and "Nerves" are in it, it should be either Adventures in Time and Space or The Science Fiction Hall of Fame, Volume Two A: The Greatest Science Fiction Novellas of All Time Chosen by the Science Fiction Writres of America.
I am pretty certain that the story you remember about someone on a raft full of aliens stalked by a giant shark is not in Adventures in Time and Space. If it is not also in The Science Fiction Hall of Fame, Volume Two A: The Greatest Science Fiction Novellas of All Time Chosen by the Science Fiction Writres of America then you should try Science Fiction: Contemporary Mythology: The SFWA-SFRA Anthology since it contains "Specialist" and "The Father-thing" which you thought were in the book you remember.