They've started hatching! Bob Wible sent me this cute "first baby of the year" birth announcement: Please help me welcome our first hatched of the season. Delivered into the loving arms of the Bakersfield School on January 10 at 3:37pm. The newly hatched and family receives a year’s supply of food and a free ride to a local stream when he or she is of an appropriate age. Alevin and family are doing fine. Here's a photo Bob sent me. Can you spot the baby? If you had difficulty finding the alevin in the photo above, here's an enlargement of it. But also look down and to the right of the alevin. I think that might be the start of some mold, or it could be the old egg shell. In either case, try to get it out of there. Are "preemies" normal? It depends on what you mean by "normal." In any group of 100 eggs some will hatch early, some will hatch late, and many will hatch at about the time you'd expect them to. It's just like human gestation. On average, women tend to deliver 280 days, or 40 weeks, after conception, but few deliver exactly at that time. The vast majority, however, will deliver in the four weeks that bracket the due date (from two weeks before the due date to two weeks after the due date). But some babies come much earlier than their due date, and a few are more than two weeks late. Here's a chart of human gestation. Perhaps your students can produce a similar column chart of brook trout hatching dates. Look out for mold! A number of schools have reported finding mold on or near their eggs. Here's a photo Sarah Stebbins, of Cold Hollow Career Center, sent to a few of us. Often this is the result of decaying egg shells. Regardless of the cause, it's very important to remove discarded egg shells and anything that looks like mold. Use your turkey baster to do this. Magnified image of embryo Danielle Levine, of Schoolhouse Learning Center, sent me several images of one of their embryos that she took using their "Dino-lite" microscope. Pretty cool! Temperature and swim-up As we've said often, temperature is the principal determinant of how quickly your fish develop. We've also said that in the past we've lost most of our fish during the swim-up stage, presumably because teachers didn't notice that their fish were swimming up and, therefore, needed to be fed (a tiny bit of food). The challenges of noticing the swim-up stage can be greatly complicated by school vacations. So, if at all possible, you want to make sure that your fish don't swim up while you're away from your classroom. We do this by working with the spreadsheet provided on the Managing Swim-up and DI page of this Web site. Using the details that pertained to SWVTTU schools, namely, that when eggs were delivered on 1/8/19, their Cumulative DI was 45.025, I've provided below three scenarios of how you might manage swim-up by regulating temperature. (The details will be slightly different if you got your eggs on a different date. You can use the "NEW 2019 Temp and DI record and swim-up calculator" to perform your own calculations.) SCENARIO #1, Hot and Fast
SCENARIO #3, Vacation ends 3/4
IMPORTANT! In deciding how to manage temperature and the swim-up stage, it's critical that you plan to keep the fry in the breeder basket for 10 days to two weeks after they are all feeding. If you release the fry too early, some are not likely to feed effectively in the "big waters" of the 55-gallon tank. These fry, which get skinnier and skinnier and are called "pinheads," eventually die.
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Joe Mark is Lead Facilitator of Vermont's Trout in the Classroom program.In June 2012, I retired after 40 years in higher education, having spent the last 32 years of my career as dean at Castleton. One of the first things I volunteered to do in retirement was to work with a parent-friend to help the Dorset School, where his kids and my Vermont grandkids attend, start a TIC program. Gradually that commitment grew into my current role, which is both demanding and highly rewarding. Archives
December 2019
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