Beattie, J.H.
Butter clams (Saxidomus giganteus) are an important intertidal resource in the Pacific Northwest. At one time butter clams were the most valuable commercial clam species in British Columbia. Although today there is no commercial fishery for butter clams, in Washington State butter clams make up nearly 35 percent by weight of the recreational harvest of all clams and compromise an important part of ceremonial and subsistence tribal clam harvest.
In spite of the importance of this clam historically, little is known about specifics of its reproductive biology. In order to increase our knowledge base on butter clams, in 1996 the Point Whitney Shellfish Hatchery embarked on a set of spawning trials. The purpose of these trials was twofold:
- Gain information that could be used in population models for resource management.
- Learn techniques that would be valuable for hatchery production should enhancement through planting of hatchery seed be desirable in the future.
The trials included:
- Gonad ripening under three temperature regimes.
- Marking of individual clams.
- Weekly repeat spawning attempts.
- Mass spawning inducement using algal density and temperature as stimulants.
- Individual spawning, egg collection and counting to determine eggs collected per female.
Results showed:
1. Butter clams are repeat spawners.
2. Amount of collected eggs is highly variable from among individual females.
3. The smallest contributing spawner was a male 29.95-mm. Shell length.
4. Significant mortality occurred in clams greater than 60-mm. Shell length.
(Washington Department of Fish and Wildlife, Point Whitney Laboratory, 1000 Point Whitney Road, Brinnon, Wasington 98320 USA)
***************