Intertidal Clam

Illustraton of a clamFour species of intertidal clams; butter, littleneck, manila, and razor clams, comprise the major portion of landings in commercial and recreational clam fisheries in British Columbia (BC). Initially, the targeted species was butter clams, which were harvested for canning at various processing facilities along the coast. Since 1971, however, strong markets and higher prices have focused the clam fishery on littleneck and manila clams, which are more acceptable on the market as fresh product. Further, manila and littleneck clams retain paralytic shellfish toxins (PSP) for a much shorter period than butter clams, adding to their appeal as a fresh product. A few other species, such as the varnish and razor clams, occasionally enter the commercial clam fishery and are utilized to a somewhat greater extent in the recreational fishery.

The clam species important to the various fisheries in B.C. include:

There are two types of commercial fisheries for intertidal clams:

Stock Assessment

Stock assessment activities relating to commercial fisheries for intertidal clams include:

  • Collaborative survey design, sample processing and analyses for the aboriginal communal commercial and depuration fisheries. Results of which are reported to Fish Management.
  • Clam collection during stock assessment surveys to identified species, number and weight, including legal and sublegal sized clams where appropriate. From these data, abundance and biomass estimates are determined from which harvest quotas can be generated.
  • Retention of biological samples from surveys to collect individual length, weight and age information in order to develop an understanding about the status of populations on particular beaches and growth patterns.
  • Surveying beaches that are going to be harvested, as well as several unharvested beaches to gain a better understanding about wild recruitment processes.
  • Provide data support services to Industry and First Nations groups including: confirming survey data quality, inputting data into an electronic format, selecting biological samples, providing sampling advice/training, confirming biomass estimates, and approving sampling designs.
  • Inputting all clam survey data collected by the Depuration fishery into the DFO's main database.

Depuration Fishery

The depuration fishery utilizes relatively new technology to allow access to product which are marginally contaminated by fecal coliform either from human (sewage or agriculture) or natural sources. Depuration is the process of maintaining live bivalves in purified seawater long enough to purge them of contamination.

The depuration fishery accesses product from marginally contaminated areas and is sanctioned under the Canadian Shellfish Sanitation Program (CSSP). This fishery is managed separately from the conventional fishery and incorporates significant stock assessment initiatives including biomass surveys and individual beach quotas. All product must be processed at a federally registered depuration facility. There are currently five processing plants approved by CFIA for depuration.

Licensed and approved processing plants are permitted to harvest and depurate clams from marginally contaminated areas in the South Coast inside waters. Depuration licences are issued under the management of Contaminated Fisheries Regulations, then the processor is assigned control and responsibility for harvest on designated beaches. The plants operate year round and provide a consistent supply to the market.

Depuration and therefore harvesting requests for contaminated areas have increased. As more shellfish beach is considered to be contaminated each year the industry will look at depuration as a way of maintaining production. In order to facilitate and manage depuration requests, in 2001, the department funded a Fisheries Manager position, allowing the entire contribution agreement to be directed to Stock Assessment. In 2002, one staff member was hired to design and layout assessment surveys, process survey samples, complete survey analysis and report results of surveys to Fish Management, with assistance of core-funded staff and Industry diggers. For surveys undertaken by Industry, this staff member approved survey design, proofed data, checked analyses and ensured that required documentation was complete for each survey.

Clam Publications

Below are some selected publications by the Intertidal Clam program.

Citations may include abstracts (HTML) or the full document may be available for viewing as an Adobe Acrobat file (*.pdf).


Gillespie, G.E., N.F. Bourne and B. Rusch. 2004. Exploratory intertidal bivalve surveys in British Columbia - 2000 and 2001. Can. Manuscr. Rep. Fish. Aquat. Sci. (in press). 124 p.

Gillespie, G.E., T.C. Norgard and F.E. Scurrah. 2001. Status of Manila clam (Venerupis philippinarum) stocks in Area 7, with a proposal for active management of a data-limited fishery. Can. Stock Assess. Secret. Res. Doc. 2001/089. 59 p.

Gillespie, G.E., B. Rusch, S.J. Gormican, R. Marshall and D. Munroe. 2001. Further investigations of the fishery potential of the exotic varnish clam, Nuttallia obscurata, in British Columbia. CSAS Res. Doc. 2001/143. 59 p.

Jones, R., C. Schwarz, B. DeFreitas, L. Lee. 2001. Results of Surveys of Intertidal Razor Clams (Siliqua patula) on Beaches Near Massett, Haida Gwaii and Recommendations on Fishery Management. 2001/152.

Gillespie, G.E. 2000. Preliminary review of experimental harvest rates in the depuration fishery for intertidal clams. Can. Stock Assess. Secret. Res. Doc. 2000/122. 52 p.

Gillespie, G.E. and N.F. Bourne. 2000. Exploratory intertidal clam surveys in British Columbia - 1998. Can. Manuscr. Rep. Fish. Aquat. Sci. 2508. 100 p.

Gillespie, G.E. and A.R. Kronlund. 1999. A manual for intertidal clam surveys. Can. Tech. Rep. Fish. Aquat. Sci. 2270. 144 p.

Gillespie, G.E., T.C. Norgard and F.E. Scurrah. 1999. Review of the Area 7 Manila clam fishery. Can. Stock Assess. Secret. Res. Doc. 99/197. 61 p.

Gillespie, G.E., M. Parker and W. Merilees. 1999. Distribution, abundance, biology and fisheries potential of the exotic varnish clam (Nuttallia obscurata) in British Columbia. Can. Stock Assess. Secret. Res. Doc. 99/193. 38 p.

Gillespie, G.E. and N.F. Bourne. 1998. Exploratory intertidal clam surveys in British Columbia - 1997. Can. Manuscr. Rep. Fish. Aquat. Sci. 2465. 43 p.

Gillespie, G.E., A.R. Kronlund and G.D. Heritage. 1998. Intertidal clam stock estimates for selected depuration harvest beaches, 1994. p. 3-46. In: B.J. Waddell, G.E. Gillespie and L.C. Walthers [eds.]. Invertebrate Working Papers reviewed by the Pacific Stock Assessment Review Committee (PSARC) in 1995. Part 1. Bivalves. Can. Tech. Rep. Fish. Aquat. Sci. 2214.

Gillespie, G.E., A.R. Kronlund and G.D. Heritage. 1998. Stock assessment of Manila clams at Savary Island, British Columbia - 1995. p. 245-317. In: B.J. Waddell, G.E. Gillespie and L.C. Walthers [eds.]. Invertebrate Working Papers reviewed by the Pacific Stock Assessment Review Committee (PSARC) in 1995. Part 1. Bivalves. Can. Tech. Rep. Fish. Aquat. Sci. 2214.

Heritage, G.D., G.E. Gillespie and N.F. Bourne. 1998. Exploratory intertidal clam surveys in British Columbia - 1994 and 1996. Can. Manuscr. Rep. Fish. Aquat. Sci. 2464. 114 p.

Kronlund, A.R., G.E. Gillespie and G.D. Heritage. 1998. Survey methodology for intertidal bivalves. p. 127-243. In: B.J. Waddell, G.E. Gillespie and L.C. Walthers [eds.]. Invertebrate Working Papers reviewed by the Pacific Stock Assessment Review Committee (PSARC) in 1995. Part 1. Bivalves. Can. Tech. Rep. Fish. Aquat. Sci. 2214.

Waddell, B.J., G.E. Gillespie and L.C. Walthers. [eds.]. 1998. Invertebrate Working Papers reviewed by the Pacific Stock Assessment Review Committee (PSARC) in 1995. Part 1. Bivalves. Can. Tech. Rep. Fish. Aquat. Sci. 2214: 437 p.

Gillespie, G.E. and J. Bond. 1997. Evaluation of harvest models for Manila clam fisheries in British Columbia. Can. Stock Assess. Secret. Res. Doc. 97/144. 44 p.

Lauzier, R. 1997. A Review of the Biology of the Pacific Milky Venus Clam (Compsomyax subdiaphana) and the Fisheries of Related Subtidal Species. 97/136.

Osborne, J. and D. Heritage. 1997. Assessment of the 1995 Seal Island Butter Clam Survey.

Gillespie, G.E. 1995. Distribution and biology of the exotic varnish clam, Nuttallia obscurata (Reeve, 1857), in the Strait of Georgia, British Columbia. J. Shellfish Res. 14(2): 578.

Stock Status Reports

DFO Science, Pacific Region, Stock Status Report C6-13 (2001), Varnish Clam.

DFO Science, Pacific Region, Stock Status Report C6-15 (2001), Razor Clam.

DFO Science, Pacific Region, Stock Status Report C6-17 (2001), Manila Clam (Area 7).

DFO Science, Pacific Region, Stock Status Report C6-02 (1999), Native Littleneck Clam.

DFO Science, Pacific Region, Stock Status Report C6-03 (1999), Manila Clam.

Integrated Fisheries Management Plans

Pacific Region, Council of the Haida Nation / Fisheries and Oceans Canada, Joint Management Plan, Razor Clam 2013. [PDF].

Heiltsuk Tribal Council/DFO Intertidal Clam 2010-11

Pacific Region, Integrated Fisheries Management Plan, Intertidal Clams, 2013-2015 [PDF].

Contacts

Clam Staff

Graham Gillespie
Tel: 250-756-7215
Graham.Gillespie@dfo-mpo.gc.ca

Jason Dunham
Tel: 250-756-7214
Jason.Dunham@dfo-mpo.gc.ca