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Topic: Difference between the Black and Blue rockfish....  (Read 7549 times)

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mooch

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An easy way of identifying each one is like comparing them to a Large Mouth Bass and a Small Mouth Bass....

Large Mouth & Black Rockfish:
If the Mouth extends past the eye

Small Mouth Bass & Blue Rockfish:
If the mouth extends to the middle of the eye (or even before)


bsteves

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Joel,

While the size of the mouth might be the easiest feature,  I've seen it abused.... Last year I volunteered to do a rockfish tagging study out at Duxbury Reef.   At one point we had plenty of fish so I stopped fishing for  a bit and helped with the actual tagging.   The head researcher (who will remain nameless) was identifiing, measuring, tagging and releasing the fish. I was simply handing him the fish from the live well.  I wasn't sure his method, but he would say to the person doing the data recording...  145343 black 250, 145344 blue 189, etc...  I finally figured out that he was calling the tag number, the species, and the length in mm.   Oddly, I heard him call out a bunch of blues despite my not handing him any blues.  Finally I saw him measure a black rockfish and call it a blue rockfish... he said "no this is a blue, check the jaw, it doesn't go past the eye." (in fact it was night quite to the end of the eye)  I reached into the tank and pulled out a blue rockfish for comparison and it was then obvious to him the difference.  A bit embarresed he corrected his mistakes and continued on with the study and didn't get one wrong again that day.  The moral of this story is not to get too tied up in things like relative jaw size.  There are other things to look at and it's best if you can see a few of each side by side.  They have different coloration patterns and general head shape that are pretty obvious when seen side by side.
« Last Edit: May 17, 2006, 09:16:06 AM by bsteves »
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Seabreeze

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Cool.  We can do a Blue/Black study group at Elk.......while we prepare for the Gyotaku..... :smt003
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mooch

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thanks for that info Brian -  :smt002  Just when I thought I got it down  :smt011

I'm glad we have an expert on board :smt023


bsteves

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Joel,

We have a tank here at the lab with lots of each.. I see what I can do about taking some comparative photos.

These are all I have right now...
Black Rockfish... notice the jaw doesn't quite go past the eye..


Blue Rockfish... notice the jaw goes almost to the back of the eye



There are plenty of good ones on the web to look at as well...

Blue rockfish (notice the black and yellow rockfish that is misnamed)
http://images.google.com/images?q=blue%20rockfish

Black rockfish
http://images.google.com/images?q=black%20rockfish

Brian
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mooch

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great comparison photos! Last question: do you guys get to eat the fish once your done studying them in the lab?  :cook



bsteves

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I don't study fish at the lab... I actually study "non-native marine species" like european green crabs and chinese mitten crabs.  I wish I still studied fish... I've tried proposing a survey of the marine reserve fish populations here at the lab using "manually retrievable ichthyofaunal sampling booms" but the reserve manager didn't go for it.

The fish in the tanks at the lab are for display (tours, etc.) and they're there long term. I'm sure the guys who do the collecting eat a few in the process.   I've been very tempted to use the tank to test lures, but I once saw the fish in the tank go nuts after a bic lighter that was accidently dropped from above by the guy cleaning the tank so I don't think they're very particular in what they eat.

If you ever make it up this way and want a tour let me know.

Brian
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mooch

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That would be cool! I've been a big fan of the Steinhart Aquarium in SF and of course = Monterey Bay Aquarium (I'm still bummed about the fact that I did not get to see the white shark back then :smt011) Growing up as a kid, I was always up for a trip to Marine World rather than Disneyland. It's also part of the reason why I'd like to get into free diving = to get to hang out with the fish  :snorkel.....and then eat them later  :smt063  :smt002


bsteves

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Before you get too excited... we have three aquaria and a tide pool exhibit... I'm embarresed that the Monterey Bay Aquarium is even mentioned in the same thread.

Anyway, we also have non-aquaria tanks with fish, lobsters (the New England type), sea grasses, etc.. that people are doing research on.  The view from the lab is nice too.  A complete tour might take 30-45 mins.

Brian
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underwater the black rockfish hang out right next to you while the blue ones scatter when you get close. there is a place at fort ross where i was diving for abalone a year ago and the school of black rockfish were about 23", right near the school sat a very big ling with a big fat smile.. that was a rare sight as most of the blacks down this way are like 14-16 inches.

i will have to go revisit that ling again. season's open.


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Blues do almost always have one characteristic similat to smallies...tiger-ish stripes on the operculum.


Seabreeze

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google definitions is my friend.................

operculum n. , pl. -la or -lums . A lid or flap covering an aperture, such as the gill cover in some fishes

Thanks for the addtional cue, Sean
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jmairey

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well I'm usually pretty good at this identification stuff and I have yet to see good pictures that really help me
see the difference.

If I could see a few of each in person, and have them identified then it would probably be pretty easy.

I need like 5 pics of each to even begin to help me see the difference.

mooch, you have a mission. take pictures of blue and black rockfish, like 10 of each and post them here, let
brian/steve whatever his name is (it's like a blue and black rockfish really,  :smt003) identify them and then
maybe I'll have a chance with this one.  :smt002

J

john m. airey


SBD

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Look at the stripes on the operculum of Alfredos smallie from Folsom...see how they kinda radiate out from the eye.



now look at the head of this blue...similar



Even cooler is that canaries have the same thing too, so if its orange with this pattern and a thin white latteral line it is a canary...



Same pattern and half of a big fat latteral line and its a copper...





« Last Edit: May 19, 2006, 05:26:43 AM by scwafish »


Seabreeze

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And Coppers have radiating "copper" lines from their eyes according the the quiz.  How come no one mentions the knobs on the heads of coppers?
Saltwater is the cure for everything that ails us,
sweat, tear or the sea.


 

anything