The Washington
Department of Fish & Wildlife (WDFW) has estimated recreational
harvest of clams and oysters on Puget Sound public beaches since about
1970. The first systematic aerial surveys of sport harvesters occurred
in 1969, and “ingress surveys” that recorded effort patterns
throughout the course of a day began the following year. These early
effort and harvest estimates involved a variety of survey methods,
and tended to focus on a few of the most popular public shellfishing
beaches.
More formal methods
of estimating Puget Sound recreational clam and oyster harvest began
following the 1994 Federal District Court order United States v. Washington
(No. 9213, Subproceeding 89-3, Judge Edward Rafeedie), which reaffirmed
the rights of treaty tribes to 50% of the harvestable surplus of shellfish.
A method for estimating the recreational clam and oyster harvest was
detailed in a 1997 appendix to the Bivalve Management Agreement (BMA)
that described general management principles for state and tribal
clam and oyster fisheries on public tidelands. The appendix remained
an incomplete draft, however, and the BMA itself expired December
31, 2002. Revised harvest estimation methods for many areas of Puget
Sound were described in appendices to the regional Bivalve Plans beginning
in 2003 (Bradbury and Strom 2003).
Currently, annual
estimates of the recreational catch of clams and oysters on public
beaches are required by regional state-tribal Bivalve Plans. Under
terms of these regional Plans, WDFW estimates recreational effort
and catch on all actively managed public beaches, and total effort
is reported on many passively managed beaches. (The distinction between
active and passive management is described in all regional Bivalve
Plans and the Glossary in this report). Besides meeting the requirements
of federally mandated shellfish management plans, estimates of recreational
effort and harvest are used to help recommend seasons and other regulations
for the recreational fishery. Harvest estimates are generated annually
for Manila clams, native littleneck clams, butter clams, cockles,
horse clams, geoducks, eastern softshell clams, and Pacific oysters.
Harvest estimates
are generated from two primary field activities: (1) aerial surveys,
which are conducted from fixed-wing aircraft to estimate total effort
(total harvester-days), and (2) creel surveys, which are conducted
on selected beaches to determine catch per unit effort (CPUE, or pounds
caught per harvester-day) by species. Additional sampling activities
that have been conducted to refine harvest estimates include low tide
counts, egress surveys, plus-tide surveys, and winter-harvest surveys.
In this report,
we describe the methods currently used by WDFW to assess the recreational
harvest of clams and oysters in Bivalve Regions 1 (Strait of Juan
de Fuca), 5 (Admiralty Inlet), 6 (Central Puget Sound), 7 (South Puget
Sound), and 8 (Hood Canal). All eight Bivalve Regions are shown in
Figure 1. In Part I, we present the current harvest estimation methods
contained in the appendices to all regional Bivalve Plans listed above.
In Parts II through VI, we present data analyses that were used to
design and justify the current harvest estimation methods. These include
analyses of the flight route, the stratification of effort, the effort
expansion factor, CPUE estimation, and the estimation of effort on
“plus tides.”
