Coastal Cutthroat Trout as Sentinels of Lower Mainland Watershed ...

59data from both records of the Fraser Valley Trout Hatchery (FVTH) and Ministry ofEnvironment’s FISS (Victoria) data base.Several hatcheries are cooperatively involved in the production of cutthroat. Adult broodfish are collected from early fall to early winter, and they are spawned from mid-December to March. Stocking of smolts occurs in spring, as well as some fingerlingsfrom summer to fall. Currently, Harrison, Chehalis, Weaver, Stave and Nicomen smoltsare cultured at Chehalis Hatchery by the Department of Fisheries and Oceans. Seymoursmolts are cultured at the Seymour Hatchery by the Seymour Salmonid EnhancementSociety, as are Alouette and DeBoville smolts by the Alouette River Hatchery, Kanakasmolts by the Bell Irving Hatchery at Kanaka Creek, and Little Campbell and Nicomeklsmolts by the Semiahmoo Fish and Game Club. The Fraser Valley Trout Hatchery viathe Freshwater Fisheries Society of BC (formerly the Fish Culture Section of the Ministryof Environment) for the most part collects, holds and spawns the brood fish, marks thefry, and distributes the fingerlings to the satellite hatchery facilities for rearing to smolts.A shortage of wild brood fish, particularly wild females, has resulted in wild-hatcherycrosses to obtain sufficient eggs, from females that average 900-1,000 eggs per female.The average size at release of smolts in the Lower Mainland Region varies from 54 to 74g, and has frequently averaged 70 g. This size equates to an average length of about 18cm. If smolt-to-adult survival of sea-run hatchery smolts was as documented by Tipping(1986) in the 1980s, this size equates to a predicted survival rate of 6 %. In comparison,larger 20-21 cm smolts survived in the 1980s at 2-to-3-fold higher rates of 12-18 %(Tipping 1986), but higher precocious development and residualism (or failure to migrateas smolts) is a risk with larger smolts (Rempel et al. 1984). It is recommended thatoptimum size at release be examined further experimentally, accounting for residualismand returns.Stocking sites are typically low in the system to minimize ecological and genetic impactsof residualism on wild salmonids, which is a sound strategy. These sites by river includeAlouette River, 216th Street downstream; Fraser River, Wahleach Slough; HarrisonRiver, Kilby; Nicomen Slough, upper Malcolm Road; Stave River, Stave Dam (DFOroad); and Little Campbell River, Highway 99.As a result of a cutthroat workshop held in Harrison in the late 1990s, there wereconcerns of genetic risks to wild stocks, as well as some uncertainty about the overall userates by anglers relative to costs of culture of large hatchery smolts (K. Scheer, pers.comm. 2004). Monitoring by the Region of the contribution of hatchery smolts to anglercatches is accomplished by angler surveys (e.g., Schubert 1992, Envirocon 1986, etc),angler log book records, and brood stock capture records. Genetic risks were consideredas related to: (1) broodstock capture was largely from two sources, by angling in themainstem Fraser and by fence captures at Chehalis River Hatchery; (2) by 1999 theincidence of hatchery fish among brood stock captures was about 75 % in the mainstemFraser and close to 95 % in some of the smaller “hatchery” systems such as the Alouetteand Stave Rivers; and (3) sufficient wild females were not captured to meet smolt goalsand thus hatchery females were being used for brood stock (40 hatchery and 33 wild