Monster Seminar Jam - Evaluating the Effects of a
Dr. Barry Berejikian, Northwest Fisheries Science Center, NOAA Fisheries
The Hamma Hamma River supplementation project is designed to evaluate the demographic and genetic effects of a supplementation program on the abundance of a depressed winter steelhead (Oncorhynchus mykiss) population. Survival, behavior, otolith microchemistry, genetic, and fish husbandry data are being evaluated to determine the relative effectiveness of two smolt-rearing strategies and two release strategies (adult vs. smolt). Growth profiles of cultured smolts have closely mimicked those of wild fish. Steelhead released as smolts (i.e., smolt release group, SRG) and as age-4 adults (adult release groups, ARG) have been observed spawning between 2002 and 2004. An average (¿ s.d.) of 11 (¿ 5.7) steelhead redds were observed annually between 1995 and 2001 in the Hamma Hamma River. After the release of steelhead from the SRG in 2000, 2001, and 2002 and ARG in 2002 (81 females, 116 males), 2003 (2 females, 2 males), and 2004 (35 females, 41 males) the number of redds observed in the Hamma Hamma River has averaged 114 (¿ 37) between 2002 and 2004. By comparison, the number of redds recorded in the control streams has remained fairly stable from 1995 through 2004. DNA pedigree analyses and behavioral observations conducted in the Hamma Hamma River and a controlled-flow spawning channel indicate a high level of reproductive performance in the ARG steelhead. Courtship in the Hamma Hamma River has more frequently been observed between ARG males and females or anadromous (either SRG or wild) males and females than between ARG and anadromous fish. The apparent assortative pairing by rearing group appears to be consistent with differences in spawn timing, which was earlier for ARG than anadromous females in both 2002 and 2004. Combined otolith and genetic analyses are underway will aid in determining the adult-to-parr reproductive success of ARG and anadromous steelhead in the Hamma Hamma River and help to identify changes in the genetic composition or life history characteristics of the target population. The findings to date suggest the potential for transitioning to a larger-scale test of supplementation in Hood Canal that would include multiple supplemented and control (non-supplemented) populations.
Date and Time:
February 10, 2005,
11:00 am - 12:30 pm