Does decline have plural form?

Question

Does decline have plural form?

Is it correct to say there were declines in the amount of fish and beef consumed in the UK?

One of my students asked me this question in an IELTS Writing class, but I was not uncertain about it.

Answer 1

I don’t see anything in the dictionary indicating “decline” can’t be plural.

there were declines in the amount of fish and beef consumed in the UK

As written, this indicates multiple separate declines in the total amount of both fish and beef consumed. I doubt that is what was meant.

there were declines in the amounts of fish and beef consumed in the UK

By making “amounts” also plural, this leads to a more likely meaning there was a decline in fish and a decline in beef.

there was a decline in the amount of fish and beef consumed in the UK

By making both singular, we have one decline in both fish and beef, with the implication of a common cause. It would most likely be interpreted as both declining, but technically it means only the total declined.

there were declines in the amount of fish and in the amount of beef consumed in the UK

This clearly says that each declined separately. You could also use “decline” here, though.

UK consumption of fish and beef declined

This is what I would probably say, but that’s just a matter of style.