One of the questions the "Caldera Assessment/FAQ document" addressed, was do the small tributaries found on the Ranch and in Last Chance provide over wintering habitat for Henry's Fork fish during the harsh winter months? This question directed us to take an intensive look this fall and winter at the three tributaries known as Blue Springs Creek, Thurmon Creek and Fish Creek. Looking at these tributaries and how fish use them will help further our knowledge of how age 0 rainbow trout survive their first winter, and to what degree these waters are used by trout. For the past two weeks, HFF has been in the field marking fish from these tributaries so that they can be followed for the months to come. By using a technique known as "Visible Implant Elastomer" or VIE tagging, HFF has marked over 900 trout from the tributaries that will be followed throughout the coming months. 
VIE tagging involves injecting a fluorescent elastomer into the fleshy skin of a fish to provide an externally visible internal mark. A unique color of elastomer was chosen for each tributary, therefore three different colored elastomers were used on the fish depending on which tributary they were collected from.
VIE tagging involves injecting a fluorescent elastomer into the fleshy skin of a fish to provide an externally visible internal mark. A unique color of elastomer was chosen for each tributary, therefore three different colored elastomers were used on the fish depending on which tributary they were collected from.
Already our marking has unveiled some surprising results as four fish marked from Thurmon Creek were found in Fish Creek one week after being tagged. These fish traveled over 6 kilometers downstream in the river and 2 kilometers up Fish Creek!
In addition to marking fish, HFF has placed thermorgraphs throughtout the tributaties to record winter water temperatures and are noting any possible habitat restrictions these systems contain. By addressing these factors, we can understand if young of the year trout are seeking thermal refuge, habitat concealment options, or both in the winter, while also looking at habitat restoration options. We look forward to understanding the part these spring systems play in regards to the mainstem river fisheries in our commitment to the Ranch and would like to offer any snow-enthusiasts to join us for a day in the field this winter!
Anne Marie Emery Miller
HFF Conservation Technician
