PARENT SESSION
SA8 - PCB Fate and Effects in the Housatonic River
Chair: Moore, Dwayne1, 1 411 Roosevelt Ave., Suite 204, Ottawa, Ontario, Canada
Co-chair: Svirsky, Susan2, Jenkins, Ken3, 2 1 Congress St., Suite 1100, Boston, Massachusetts, USA3 Blasland, Bouck & Lee, Inc., Long Beach, CA
8:00 AM to 12:00 PM - Sunday, 17 November 2002
Room Ballroom C
(075) Largemouth Bass Reproduction and Population Dynamics in the Housatonic River, Massachusetts.
Reiser, Dudley*,1, Greenberg, Emily1, 1 R2 Resource Consultants, Inc., Redmond, WA, USA
ABSTRACT- Largemouth bass (Micropterus salmoides) are a currently unexploited gamefish species in the Housatonic River, due to a fish consumption advisory related to the presence of elevated concentrations of PCBs in the fish. In 2000 and 2001, we investigated the following in a 10-mile stretch of the Housatonic where some of the most elevated levels of PCBs have been observed: 1) natural reproductive periodicity and success of Housatonic largemouth bass; 2) potential exogenous sources of recruitment; 3) abiotic parameters important to year class strength; and 4) the general bass population structure. The majority of spawning habitat was contained in backwater areas within or directly connected to the mainstem of the river, while the majority of tributaries contained lotic-type habitat unsuitable for bass spawning. Largemouth bass nests and spawning activity were documented in 15 index sites that we selected for observation, and broods of larval bass were observed in all index sites that contained active nests. In 2001, the first brood of larval bass was found 19 days after mean water temperatures increased above 15.5°C. Growth rates were strongly correlated with river water temperatures. The range of early life-stage growth rates observed in the Housatonic River falls within the ranges of other northeastern USA populations. Young-of-year catch-per-unit-effort (CPUE) at the end of the growing season was also comparable, and the Relative Weight (Wr) values for Housatonic River bass were consistently above the largemouth bass standard of 100. Reproduction, young-of-year growth, relative density, and population structure indicate that the largemouth bass population is successfully reproducing within this reach of the Housatonic River, and that year class strength is likely determined by several density-independent factors, such as air and water temperature, dissolved oxygen concentrations, cloud cover, and flow.
Key words: Micropterus salmoides, PCB, reproduction, Housatonic River