Alaska Section, American Water Resources Association

Richard Kemnitz, Alaska Section AWRA Northern-Region Director

I would like to invite you to the April 2000 Brown-Bag presentation by Scott Maclean, USGS, Alaska Biological Science Center. Please note this meeting is the second Wednesday in April. Scott's talk will be a presentation of his efforts on quantifying spawning habitats. This research has applications in ground-water and surface-water interactions, defining critical habitat reaches in spawning streams, and in improving our general understanding of the Salmon spawning cycle. We look forward to seeing you, please feel free to bring a colleague to the meeting.

April 12, 2000
Alaska Section AWRA, Northern-Region Brown-Bag Presentation
Alaska Department of Natural Resources, Large Conference Room
Noon to 1300

"Quantification of Upwelling as a Determinant of Spawning Site Selection and Quality for Yukon River Chum Salmon"
Scott Maclean, USGS, Alaska Biological Science Center

Although chum salmon in Alaska often use areas of upwelling for spawning, no quantification has been made of the importance of upwelling in terms of defining available spawning habitat or its effect on the survival of incubating eggs and alevins in the Yukon River drainage. Within the framework of ongoing USGS-BRD Yukon River chum salmon research, we are evaluating the spatial distribution of upwelling and other intragravel environmental factors in one summer-run, Chena River at Hodgin's Slough, and one fall-run, Tanana River at Bluff Cabin Slough, spawning area. Our overall study objectives are:

1) Measure the relative magnitude and distribution of upwelling in one summer-run and one fall-run chum salmon study site from the time of spawning (i.e., fertilization) through emergence.

2) Compare the distribution of spawning fish within each study site to the distribution of upwelling.

3) Compare the survival of eggs and alevins incubated across a gradient of upwelling and other environmental conditions.

During 1999 we systematically deployed mini-piezometers (stand pipes) along transects in both summer-run and fall-run chum salmon spawning areas. These piezometers allowed us to measure the hydraulic pressure differential between subsurface and surface waters, substrate permeability, and subsurface water velocity. In addition, we have measured and are monitoring dissolved oxygen (DO), conductivity, and temperature within each piezometer. At each study site, piezometers were installed in a geo-referenced (Universal Transverse Mercator (UTM) coordinates) grid pattern along transects. Adult fish weirs were used to enumerate adult fish in each study site and the positions of individual spawning females were recorded as UTM coordinates.

Initial hydraulic and water quality measurements were collected during late July (Hodgins Slough) and mid-September (Bluff Cabin Slough). Measurements in Hodgins Slough showed large variation in hydraulic variables, temperature, and DO. Relatively distinct patterns were evident for temperature, DO and VHG. In contrast, measurements taken in the Bluff Cabin Slough study site indicated a more homogenous environment with the exception of VHG, which appeared patchy. Redd location measurements appear to follow spawning distributions observed during the 1997 and 1998 spawning seasons. Temperature and DO appear to match observed spawning distributions best at the Hodgins Slough study site.

Survival of eggs and alevins is being evaluated using in situ incubation baskets. The incubation baskets were buried in clusters of three associated with individual piezometers. Deployment of incubation basket groups was determined after collecting initial hydraulic and water quality measurements. During this winter, one basket was removed from each group at the eyed-egg stage and one at the pre-emergent stage. The third basket will remain in the gravel until emergence (May, 2000) and live and dead individuals enumerated.

We feel that the techniques employed will provide a quick and relatively inexpensive means to quantify the subsurface environment in remote salmon spawning areas. Measurements from our study sites will begin to describe factors influencing chum salmon spawning site selection and the subsequent survival of incubating eggs and alevins. Certainly our first winter of attempting to take these measurements in the harsh interior Alaska environment has been a test of the overall feasibility of our methods.