To me it would be 'clutch' for a single batch of eggs and 'clutches' where it needs to be specific is they were the result of  polygamous spawnings or from a single female

Thanks a lot, Michael. That's what I would have done, too. The "trouble" appears when one (well, I) is to put a name to the totality (the sum) of eggs cared for by a male, say, goby or damselfish. Then I want to be able to report that the mean ???? size was 3427±467 eggs, that 84% of the ???? hatched, and that 12% of ???? were cannibalized. My problem is then what term to use for ????. As I haven't been successful in finding a standard terminology I fear that I and my co-workers/students have sometimes used 'brood' and sometimes 'clutch' in such cases. I've heard fish people suggest that a brood is the sum of individual female clutches in such cases (whether spawned by one or more ff). And it's often but far from always used that way, at least in the goby literature that I know the best. But originally coming from a bird scientist background that sounds like a strange solution to me. 

The situation described above is, for instance, relevant if one wants to estimate selection gradients or differentials, where either # eggs (???? size) or # hatched eggs would be the best fitness approximation available (of course # eggs is an option, but that kind of goes around the problem).

Maybe the only solution is to make sure that the context clearly specifies the meaning of the term used. That's what I've tried to teach my students. But I'm not entirely happy with that half-way solution.

I may care about this because I teach science methods classes to stick to one well-defined term for the same thing in science writing, rather than using "rich language". But also because I think the literature in ecology, evolution and behaviour is rife with terms that do not have a consistent and precise meaning across authors.

We use the term "brood" for any egg mass cared for by a male fish, independent of female origin. I agree with inconsistency of language.

Thanks Leon. That's what we mostly do, too, and specifying our terminology explicitly in the text. But to me it's almost 'unbelievable' that there isn't an 'official'/consensus terminology (if I'm not mistaken). I've raised the issue with various people before, but thought "maybe try RG" when I again faced the issue with an ongoing ms. So I'm curious about more views.

 For the egg mass cared by a male fish, I would not use the term clutches as in some demersal spawners (i.e. some blennids, some pomacentrids,etc.) females may parcelize their clutches (i.e. the group of simultaneously mature eggs laid)  in the nest of  more than one male. I would  use the term "brood", explaining in the text what you mean. Anyway,  I agree with you that the language is not standardized

Thanks a lot, Maria; that's a good point. Which makes me wonder about yet another thing: when does the clutch become a clutch? I have thought of a clutch as something that is non-existing before being "laid" (deposited/spawned) - I've thought that it's "only mature eggs" (that's how it would be with birds). But I see the point of considering the batch of simultaneously mature eggs a 'clutch' even before laying. 

I also see the point of considering the sum of part-clutches deposited in two or more nests right after another as the female clutch. On a practical, note, however, one (at least we, working with small gobies) would often deal with nests with 'broods' that can be assigned to 3-6 females, an for which # eggs deposited by each female can be estimated. But where one would not know whether some of the females may have only contributed part of their clutch to that nest, either "by strategic decision" or as a consequence of spawning interference. If, in such cases, one would want to quantify female clutch size, one would inevitably mix part-clutches and complete clutches. 

But perhaps that's not much of a problem. We've got to compromise in the real World...

This is a good one! What is a clutch of eggs, what an egg mass and what a multilayered clutch as result of egg deposition by several females?

Technically a clutch of eggs is the number of eggs laid by a female independent if spawning on e.g. substratum, in a nest or pelagic. Nevertheless this term also refers to groups of eggs laid in a nest by more than one female. In such cases eggs may form a multilayer clutch or a multilayered egg mass, e.g. in many gobiid fishes or in sticklebacks.

As far as I know there is no term for such a ‘sum of clutches’ except the not very helpful term ‘egg mass’, if forming a clump or a multilayered clutch / egg mass. Mostly there will be no other way to disentangle the question how many females led eggs in the nest and which eggs are from which female except by DNA.

I think the term brood should not be used for eggs but for already hatched fish which were spawned at the same time. Usually brood is used in guarding species like cichlids and sticklebacks which take care of their offspring after hatching.

 I agree with Leon and Maria. There is inconsistency of language. 

Hi Trond,

Why not simply state that its the number of eggs in a nest? i.e. the mean number of eggs in a next was ????. This might get around some of the semantic issues.

Hi Trond!

I agree with Herald, Leon and Maria, so why don't you propose a new term?. I thought that multilayered clutches could implies an spatial arrangement that is not necessarily true, so why don't you simply designate them as poly-female-clutch? Or something like that, that gives to the reader a clear idea of what the nest contain. 

The language must help us to communicate ours findings and thinking, so, if the lenguage is inconsistent, as all above had said, we must work to make it clear and consistent.

Best regards,

Silvia 

I agree with Harald Ahnel

Coming in really late here....a year later!   I just saw the discussion and thought I would pass on my preference.  Neither term is perfect.  Brood technically means young of roughly the same age that hatch at the same time.  To brood means to keep warm which fish don't do.  However, many cichlid mouth brood.  So  I try to use brood to mean the eggs in a nest or in the mouth that are taken care of by parent fish (males or females).  I use the word clutch to refer to the eggs that a female lays.  So here are some examples of what I might write or say:  Biparental cichlid parents take care of a brood of eggs. Midshipman males guard a brood of young.  Round goby males will defend a brood of eggs inside a shelter.

Thanks for your response, Sigal, and I agree. I believe seeing it from the female's side (clutch) vs that of the carer(s) (brood) is the best way of dealing with it. I guess what becomes a bit awkward is when you have to extend statements like your last sentence to say, for example: Round goby males defend a brood of eggs, consisting of clutches laid by 3-6 females, inside a shelter.

Coming from the bird world, where eggs from multiple females in the same nest are rare, I'm used to use the two terms to describe stages of development: clutch for eggs, and brood for nestlings resulting from those eggs. Obviously, this terminology neither matches the "brooding = warming" meaning: clutches are typically warmed whereas broods of nestlings need no warming during major parts of their development.

Whatever. As said, I agree with your suggestion. And I'd be pretty generous with the 'roughly same age' requirement, as the extent to which clutches making up a brood are of the same age varies a lot within and between species. Cases like sphinx blennies, where broods are more or less continuously refilled (according to a paper by Sarah Kraak), becomes troublesome with that requirement. Maybe it's enough to say 'simultaneously cared for"?

I believe fish science will continue to use the terms inconsistently. I'm a big fan of unambiguous terminology, buy maybe one just has to face reality...

Agree with every word you wrote