Catshark / Dogfish

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Catshark / Dogfish

Right then - with regards to Small-spotted Catshark / Lesser-spotted Dogfish (Scyliorhinus canicula).

What do other PSLers think about the merits of ticking this species from a live egg-case? Normally I would try to rear something through but no exactly geared up for rearing marine sharks!

Gibster (not verified)
If you know the egg is viable

If you know the egg is viable and the contents alive then that's got to be good enough to tick. Presumably, to ascertain that you'd have to see the unborn fish inside and either attach a tiny stethoscope and listen very carefully (!) or see the it moving. I think most of the cases washed up at the strand line probably contain a dead fish?


Hmm! Certainly a fish in the case, but no stethoscope in my woefully inadequate rock-pooling kit so I'm going to forget I ever saw it.

So I have seen many egg cases

So I have seen many egg cases which for me are good enough for records BUT it's NOT one of the 69 species of fish on my list, depsite seeing dead ones too. It just doesn't feel right to me ticking a dead vertebrate. It's all preference though, if it feels right, go with it! I'll wait for a live fish though, there are plenty of other things to tick out there in the mean time!

If the embryo is alive, then

If the embryo is alive, then all is good. Given that I have ticked galls without seeing live occupants, maybe that is inconsistent but ticking invisible or dead things troubles me! Luckily I've seen several live and twitching adults so less of a dilemma! :)

ticking gall species without

ticking gall species without rearing or examining the occupant makes me uneasy. Of course this is fine as a biological record, but is not a PSL the number of species seen? If you rear the contents of a gall more often than not you get parasitoides and inquilines but no gall-former. Often nothing emerges because the gall-former failed to develop, and was possibly dead when found in the field.

If a PSL is not any different than ones amassed biological records, then we can count road kill, chewed nuts, footprints, the contents of owl pellets, a sonogram from a bat-detector and perhaps before long a sample of pond water and a DNA sequencer will give us a total list of the fauna and flora in the pond?

Now there is a thought. Is

Now there is a thought. Is such a DNA sequencer yet available? :D

I'm sure that there is truth in what you say Dave. Maybe it is time to clean my list of the handful of galls that I have ticked without seeing occupants - for the vast majority, either I have seen the live contents or seen adults. I guess I was illustrating that dead vertebrates are the extreme end of the spectrum. I have never ticked dead invertebrates in pitfall traps. And I have certainly never ticked a chewed nut. At least not the chewer :D