We started to look at our collected telescope shiners' ovarian condition today, starting with one female collected on April 7. Monthly collections of 40 individuals began in February in Hurricane Creek at the Walls of Jericho in Alabama. We earlier removed entire gonads from individuals, and stored the gonads in 10% buffered formaldehyde. Our interest is to characterize reproductive effort throughout the apparent breeding season, calculating gonadosomatic index (GSI) and counting and measuring eggs. Our method is to digitally photograph the excised ovaries, then break them apart and photograph the ova in a series, and count and measure them using Motic software.

Here's a shot of a set of ovaries at X10 magnification. The fish they're from was 47.2 mm SL, and weighed 1.6 grams, with a GSI value of 7 (=percentage of body mass that's ovary). The ovaries are about 15 mm long, and 3 mm in diameter.


It took seven pictures to photograph all of the developing eggs we removed from the ovaries. Three developmental stages are visible, from the small, grayish cortical alveolar stage to late exogenous vitellogenesis (the big yellowish ones). The largest eggs are just over 1 mm in diameter. I estimate that we photographed a total of 450 - 500 eggs in the seven shots.

fundulus,

I want to see ovarian egg turnover to get an accurate handle on fecundity. How many of those ovarian eggs are laid in a reproductive bout? How frequent are the bouts?

fundulus,

I want to see ovarian egg turnover to get an accurate handle on fecundity. How many of those ovarian eggs are laid in a reproductive bout? How frequent are the bouts?

That's what we're working on in part. Typical Notropis species spawn at roughly 5 day intervals, and needlessly to say produce multiple clutches. Once we've measured a large number of ovaries I would expect that we'll have frequency histograms of ovum diameter that will show multiple size classes reflecting the presence of ova at different stages of maturation. To directly address your question, we hope to host some captive spawning ourselves which should show how many eggs are produced in a bout. Much of our methodology is based on David Heins' work over the last 30 years, such that we aim to answer questions including yours with accuracy. See especially, D.C. Heins and F.G. Rabito Jr., "Spawning performance in North American minnows: direct evidence of the occurrence of multiple clutches in the genus Notropis", J. Fish Biol., 1986, 28: 343-357. The Notropis in this article, leedsi, has since been placed in the genus Cyprinella.

To add aggrevation, I have found the spawning frequency / volume of captive animals (derived from a given population / locality) to vary considerably as a function of diet, stress and history. Getting a the captive animals to provide the reproductive output typical of the natural situation will prove to be challenging. Refractory period can really be variable. Your, telescope shiners, they are egg scatterers I presume. Have you considered the possibility female spawning bouts occur at 24 h intervals instead of five days. They are in many ways similar to some african tetras that breed daily like clockwork so long as feed intake supported it.

To add aggrevation, I have found the spawning frequency / volume of captive animals (derived from a given population / locality) to vary considerably as a function of diet, stress and history. Getting a the captive animals to provide the reproductive output typical of the natural situation will prove to be challenging. Refractory period can really be variable. Your, telescope shiners, they are egg scatterers I presume. Have you considered the possibility female spawning bouts occur at 24 h intervals instead of five days. They are in many ways similar to some african tetras that breed daily like clockwork so long as feed intake supported it.

You're right; if I really knew what was going on it wouldn't be research. Captive spawning only gives you a ballpark idea of what happens in nature. I haven't heard of any notropines spawning on a daily basis in captivity. Telescopes seem to be egg scatterers in nature and it would be difficult to view that activity precisely in a riffle that's 30 cm deep. The easy datum to generate is average GSI value with standard error from month to month, along with direct examination of the condition of ovaries. Male condition is of interest too, since it takes two to tango. The odd thing was that males were untuberculated in April while ovarian condition was advanced. We'll see...

You're right; if I really knew what was going on it wouldn't be research. Captive spawning only gives you a ballpark idea of what happens in nature. I haven't heard of any notropines spawning on a daily basis in captivity. Telescopes seem to be egg scatterers in nature and it would be difficult to view that activity precisely in a riffle that's 30 cm deep. The easy datum to generate is average GSI value with standard error from month to month, along with direct examination of the condition of ovaries. Male condition is of interest too, since it takes two to tango. The odd thing was that males were untuberculated in April while ovarian condition was advanced. We'll see...

Could you create a super spawning site? One that you can control appearance and placement in the 30 cm riffle that they would prefer over the naturally available options. Your shiners may have a hankering for freshly disturbed gravel in which to deposit spawn. May facilitate observations. Could you mark a few with visible implantable elastomere (VIE)? I can field ID free swimming bluegill and redspotted sunfishes so marked (sunlight causes VIE to flouresce). You may detect a degree of spawning site fidelity or find males can get it up when ever a gravid ripe female is about. A problem with VIE is that is may show up a lot in kingfisher and spotted bass feces.

I've toyed with the idea of intense field observations using something like VIE. But for now, my major interest is evidence of physiological investment in spawning as opposed to the exact nature of egg deposition. The truth is that I don't have the time or research (student) cadre to set up that kind of mark and observation design. A direction I might take from current work is to examine nuances of brain structure, and hormonal levels such as 11-keto-testosterone, as indicators of reproductive competence and activity. It's an odd thought but at the moment I'm better set up to do western blots than to do extended field observation.

Having said that, Hurricane Creek at the Walls of Jericho would be an ideal place to do in-depth field work. It's relatively remote on state lands with friendly management, and it's possible to camp there for extended periods. If anyone's up for it, let me know, there are almost limitless possibilities on the site.

And I hope everyone's enjoying a good Earth Day! The weather in north 'bama has been sunny and about 80 F.

I've toyed with the idea of intense field observations using something like VIE. But for now, my major interest is evidence of physiological investment in spawning as opposed to the exact nature of egg deposition. The truth is that I don't have the time or research (student) cadre to set up that kind of mark and observation design. A direction I might take from current work is to examine nuances of brain structure, and hormonal levels such as 11-keto-testosterone, as indicators of reproductive competence and activity. It's an odd thought but at the moment I'm better set up to do western blots than to do extended field observation.

Having said that, Hurricane Creek at the Walls of Jericho would be an ideal place to do in-depth field work. It's relatively remote on state lands with friendly management, and it's possible to camp there for extended periods. If anyone's up for it, let me know, there are almost limitless possibilities on the site.

And I hope everyone's enjoying a good Earth Day! The weather in north 'bama has been sunny and about 80 F.

I am at Reel Foot Lake so my weather is nearly same. Brain structure morphology or activity? How will you be detecting 11-keto-testosterone levels? As a followup to a behavioral study we have been considering doing the same. Would like to do so with minimal stress to animals. Is that the type locality for the crayfish Orconectes mirus?

I am at Reel Foot Lake so my weather is nearly same. Brain structure morphology or activity? How will you be detecting 11-keto-testosterone levels? As a followup to a behavioral study we have been considering doing the same. Would like to do so with minimal stress to animals. Is that the type locality for the crayfish Orconectes mirus?

For 11-KT, we're using ELISA. The big challenge is to get 40-50 microliters of blood; unfortunately this requires the fish's sacrifice. We're trying to relate intensity of male scarlet shiner breeding coloration to levels of 11-KT. As to the crayfish, I'm not sure... but the creek is loaded with all sorts of crayfish that are unfortunately easy to catch in a seine net.