Managing Swim Up & DI
鈥淪wim-up鈥 is a stage that occurs when alevin become fully developed (when they鈥檙e called fry). Prior to that point, alevin have been living on the bottom of the breeder basket, but when they approach being 85 or 90% developed, they start making tentative movements towards the surface. Experienced fisheries biologists like Roxbury hatchery鈥檚 Jeremy Whalen can recognize the fairly subtle cues that indicate the alevin have reached the swim-up stage. But听TIC teachers and volunteers, who observe only a comparatively small number of alevin and who raise trout just once a year, usually find it very difficult to spot the telltale signs of the swim-up stage. As a result, we need to use听data听to predict when alevin will swim up.
And for this, we鈥檝e created a data entry sheet and a special 鈥渟wim-up calculator,鈥 which you can find .听 Two quick notes about the Excel and Google Sheets files contained in this folder:
- One is an听Excel听workbook called 鈥淭emp and DI record and swim-up calculator鈥; another is a听Google Sheets听workbook of the same name. Both contain听four听worksheets. The first provides instructions, the second is used to听PREDICT swim-up and to record water temperature data, the third will allow you to听SCHEDULE听辞谤听CONTROL when the fry swims up, and the fourth you won鈥檛 need to use; it simply allows a formula to perform a 鈥渓ookup鈥 function.
- If you鈥檙e going to use the Excel workbook, in order for the formulas to work, you need to open the Excel file,听not听be looking at the file from within a Web browser such as Chrome. Download the spreadsheet and save it to your hard drive. (If you don鈥檛 have Excel, use the Google Sheets document.)
- The other two files are Excel and Google Sheets spreadsheets that you should use for recording temperature, pH, water chemistry readings, etc. It鈥檚 important that you also record egg or fry mortality and other observations such as swim-up behavior.
It鈥檚 extremely important to know when your fry are approaching 85 or 90% development (DI = 85) because that鈥檚 when the fry should be swimming up and looking for food. But the swim-up stage lasts only a few days鈥搃t鈥檚 a briefly opened window鈥揳nd, if you miss it, you鈥檝e听missed it, probably for good! So it鈥檚 critical to know when to be looking for the telltale signs of the swim-up phase and to be able to spend time watching for those signs so that you can respond to them appropriately. See the resources below.
