Mature Yellow perch can be easily sexed just prior to spawning by the distended abdomen of the female that is full of eggs, and the lack of a distended abdomen of the male. Milt also is easily exuded by the male with slight hand pressure toward the urogenital orifice.

As you can in the following photo the male is smaller and lacks the distended abdomen of the female fish. These fish are the same age. Female yellow perch grow faster and larger than males.



Closer to spawning time the females become very grossly distended as in the following photo. Very hard to confuse this with a male!

Here's a study I found on the Internet by the following authors to help sex yellow perch other times of year. As you will read the larger and older the perch the more accurate the method.

Great Info - thanks for sharing and educating us.

Bill,

I used this guide last year when removing perch from the big pond before draining it, and then again to be doubly sure before putting them back. The illustrations and photos matched the vent appearances of the bulbous females and males that exuded milt. I sent all the males to Scott's pond.

So I sorted twice for both bluegill males and yellow perch females and hopefully I was 100 percent accurate.

There were a few perch that appeared to be males but did not exude milt. I sent those to Scott's pond to play it safe. Not sure if they were males that weren't mature yet or females that dropped their eggs early. Or perhaps sterile?

Bill,

What did you think about the comments about the scaleless area around the urogenital opening for female bluegills?

Scaleless area is present on mature fish that I've examined. One has to look closely especially if you need bifocals. I was thinking you were providing specific information about BG not YP?

Thanks for taking the time Cecil.

Yes bluegills. That particular comment was on the bluegills on the third page of the post, second paragraph. It said 100 percent accurate for sexing. Do you concur?

No problem.

I question if it is 100%. It probably depends on who is doing it.

Numerous studies have shown that with many species even the experts don't get near 100% on species or sex. You would be shocked at the low % right in some studies.

That's true Eric. Bobby Glennon a biologist at Malone and Sons once told me he has to see eggs or milt to sex bluegills 100 percent. I believe he probed for the eggs with a tiny catheter tube.

I will add some close up photos of the urogenital and anuses of large male and female yellow perch before I add them to the spawning cage in the next few weeks. Additionally I will do so with tank raised YOY perch that are presently in my basement.

Stay tuned!

IMO it is much easier to use urogenital features during pre and post spawning season versus during mid summer and fall when openings have had time to reshape back to more normal shapes.

Of course, but the idea is there are physical differences during other times of year too albeit perhaps not as pronounced. My hope is the tank fish will be a better test as not only are they shy of a year old, they haven't mutured sexually like fish that were winterized. There are definitely some smaller fish in the tank that I will bet are males.

However I will also take pics of female fish in mid summer and if we can get it done of marked fish in Scott's pond as I won't have any males here.

Cecil
Thanks for all the good and timely info on sexing YP. I caught and ate several from my pond the other day, attempting to sex them before they got the knife.
As an aside, last week we caught 19 NP from a local lake, a BOW that most Pond Boss readers would consider a pond (approx. 200 acres. As many people know, we here out West call trickles "creeks", creeks "rivers", and our river "the Colorado" Ha!) The pike had not yet spawned. The overlap in length between females and males was nearly non existent, as all males but one were 20" to 23"; all females but one were 24" to 30".

Hope all you northern pondmeisters are seeing open water.

Roger

Interesting. I have a good pictoral on sexing pike by their genitals somewhere around here and will post it when I find it. It came out of the In-Fisherman magazine of all places but originally came from a study.

The female pike were definitely were full of eggs right?

Yes Cecil, plump with eggs. Today we were out to the same spot on the same lake, trolling similar lures. The 13 NP we got today were noticeably smaller than those others on average, running 20" to 24". Of the 5 I cleaned, 4 were males; 1 was a female. I'll check with the other fishermen tomorrow to see what their gender breakdowns were. Of course this is still a small sized sample. Just something I'll add to my log of fish observations.
Roger

Today I removed from one of my recirculating tanks about 133 barely 1 year old 7 to 11 inch yellow perch that I hatched in one of my ponds last spring. I had put them into one of my indoor systems in the summer in my basement to overwinter them. I have another 66 at two local high schools I will pick up in a few weeks.

My biggest pond is female only yellow perch, so I attempted the best I could to sex them to plant only the females into the pond. This proved to be much more difficult than if they have eggs or produce milt.

The drawback to bringing them in for the winter is there is no chill period to cause them to develop sex products which makes them easy to sex. The fact that the fish are barely 1 year old may also be a factor.

Using the above technique for sexing fish I came away with the following conclusions:

1.) There definitely were fish that met the visual requirements to tell which sex they were by the appearance of the urogenital opening but there were many more that were not clear cut. Those fish went to a floating cage.

2. The finger pressure anterior of the anus didn't seem to produce a pointing of the urogenital opening in any of the fish as in perch I suspected to be males. Perhaps I should have used magnification?

3.) There seemed to be a wide variation in the so called half moon or crescent shape of the urogenital opening in females as in very distinct in some and not so distinct in others.

4.) I did not observe any swelling around the anus due to finger pressure in any of the fish especially the ones that appeared to be females. Then again perhaps I should have used magnification.

4.) To get better confidence in sexing yellow perch I will have to get them to produce sex products. I need 100 percent accuracy.

BTW the fish ranged in size from 7 inches to 11 inches.

Here are a couple of photos of fish urogenital and anal openings I took.

This fish clearly showed the crescent shape of the urogenital opening in a female. It made sense as it was a large fish vs. much smaller ones that appeared to be males.



This fish fit the visual criteria for a male and was much smaller than the other fish as is typical for a male.

Great thread Cecil.

You should consider putting this years YP crop through a minimal cold period so you can better recognize male vs females next spring.

For sure. Either a chiller inside or put them in a cage this winter. I prefer the latter as chillers are expensive and I'd have to increase my biofilter size substantially.

Too bad you couldn't pump the 54°F well water thru the inside tank to drop the temp.

Flow through could be an option but how long would it take? There's only one study out there that documented the time it took at a particular temp and it was in Minnesota. It was something ridiculous like 180 days. My guess is it would be less days and higher temos for more southern strains.

I'm going to talk to Rob Rode of Purdue and ask him. He accidentally got an off season spawn in a perch tank. Somehow the water got cold and he didn't know about it.

I think if you dropped the temperature to 50-55F for 30-40 days that would be enough to stimulate egg production. Keep in mind that YP start developing eggs in August of the prior year to spawning. Thus I am not sure why the cold period is mandatory. I have cleaned YP in the Sep-Oct that contained developing ovaries (eggs). Take that info to Rob Rode and report back here. Thanks.

Take that info to RR and report back here. On the double.
YES SIR

Not you Bob, Cecil!