Science Leading to the Protection of Puget Sound Rockfish

Quantifying historical fishing pressure on and population trends of rockfish in Puget Sound to determine listing status under the Endangered Species Act.

West Coast

Historical Fishing Pressure on Rockfish in Puget Sound

Figure 1. Map of Puget Sound geographic features and place names. Symbols indicate the following: major zooarchaeological sites (filled triangle), traditional native American rockfish harvest areas (filled circle), major groundfish trawling grounds during the 1930s (crosshatched polygon), and multiple records of yelloweye, canary, and bocaccio rockfish from recreational catch during 1960–1970s (open circle with dot). See Williams et al. 2010.

In Puget Sound, WA (Fig. 1), rockfish (Sebastes spp.) have significantly declined in abundance, with multiple petitions to list individual species under the Endangered Species Act. We reviewed the local history of rockfish fishing to better understand the ecological legacy of rockfish fishing to the Puget Sound ecosystem. We focused on the socioeconomic forces and management decisions that influenced landings' trajectory (Williams et al. 2010).

People have long harvested rockfish for food here. Over time, exploitation patterns have changed from an opportunistic subsistence activity by indigenous peoples to a year-round target of commercial and recreational interests. Annual commercial and recreational harvests together peaked (almost 400mt) in the early 1980s as anglers' attitudes changed, gear technology improved, rockfish became more familiar to the market, the human population increased, and government programs promoted fisheries to sustain employment (Fig. 2).

The top panel of Figure 1 shows the estimated commercial and recreational catch of rockfish from Puget Sound, 1920-2007. Commercial fishing for rockfish peaked several times from 1945 to 1990 and then going to nearly zero by 2000. Recreational fishing for rockfish was heavy from the 1970's thru the early 1990's and then dramatically declined through the 2000's. The bottom panel of Figure 1 shows rockfish catch data with overlay of key regulation changes from 1970-2007. The first rockfish management plan was — Figure 2. (top) Estimated commercial and recreational catch of rockfish from Puget Sound, 1920-2007. (bottom) Catch data with overlay of key regulation change, 1970-2007. See Williams et al. 2010 for footnote details.

Fishery managers did not intensely manage rockfishes with conservation goals in mind until the late 1980s, in part due to scientific shortcomings and a lack of resources. The greatest harvest had already occurred by the time fishery managers deemed conservation measures necessary. However, the long-lived, slow-growing, and late-to-reproduce characteristics of most rockfish species suggest that the legacy of fishing will remain for years to come. As managers strive to restore the integrity and resilience of Puget Sound, we must understand the significance of historical fishery removals to the ecosystem and use the proper social and economic incentives to drive individual behavior toward these ecosystem goals.

Assessing the Size of Rare Populations with Limited Data

In 2007, we were petitioned by a public citizen to list five rockfish species in Puget Sound, WA, under the Endangered Species Act (ESA). One of the criteria for listing a species under the ESA is a determination of the species' level of extinction risk. This determination generally consists of measuring a population's growth rate to investigate both absolute abundance levels and relative trends over time. However, standard analytical methods typically require detailed data over time and space that is generally not available for rare or threatened species.

Figure 3 shows estimated trajectories of North Puget Sound and Puget Sound Proper rockfish population abundance from 1977 to 2014. The North Puget Sound trajectory varies more than Puget Sound Proper, but overall, both regions show an approximate decline in abundance of about 3% per year over the time period. — Figure 3. Estimated trajectories for total rockfish from recreational fishing surveys in northern reaches of Puget Sound (black line) and Puget Sound proper (red line) based on the best‐supported models (Tolimieri et al. 2017).

Here, we took advantage of three disparate data sources (recreational catch surveys, REEF citizen science SCUBA surveys, and bottom trawl survey data). We developed analytical methods to overcome limited data specific to these five species. These methods allowed us to quantify relative long‐term trends of all rockfish species combined in Puget Sound, WA. The best‐supported models indicated that all combined rockfish species in Puget Sound declined at similar rates from 1975 - 2014 (an average of −3.8% to −3.9% per year; Fig. 3) in both the northern and southern portions of Puget Sound (Tolimieri et al. 2017).

Figure 4 shows the proportion of Bocaccio, Canary rockfish and Yelloweye rockfish in the recreational catch of all rockfish over time from the 1960's to the 2010's. Each species proportion peaked in the 1960's or 1970's and declined to levels more than half their peak levels by the 2010's. — Figure 4. Change in proportion of total rockfish assemblage for Bocaccio, Canary rockfish and Yelloweye rockfish (Tolimieri et al. 2017).

Three of the five petitioned rockfish species declined as a proportion of recreational catch between the 1970s and 2010s. This suggests that they experienced similar or more severe reductions in abundance than the 3.8–3.9% per year declines we estimated for all combined rockfish populations (Fig. 4). We used these analyses, plus other information related to life-history characteristics of each species, to decide that:

Bocaccio was at a high risk of extinction.
Canary and Yelloweye Rockfish were at moderate risk of extinction.
Greenstriped and Redstripe Rockfish were not at risk of extinction (Drake et al. 2010).