Science Leading to Recovery and Delisting of Puget Sound Rockfish
Using genetics, experimental fieldwork and computer modeling to determine whether rockfish species meet criteria and recovery goals of Endangered Species Act.
Testing the Validity of ESA Listings with Genetics
Population genetics is an essential tool for determining the appropriate taxonomic units of fish species. We listed Yelloweye Rockfish (Sebastes ruberrimus), Canary Rockfish (S. pinniger), and Bocaccio (S. paucispinis) in the inland waterways of Puget Sound, WA under the U.S. Endangered Species Act (ESA) in 2010.
These listings relied heavily on scientific evidence from other species or other geographic regions supporting these populations being 'discrete' taxonomic units. We used indirect information because little information was available for these species in Puget Sound. We collaborated with recreational fishing communities in Puget Sound to fill this gap. We fished with volunteer anglers to collect tissue samples (Fig. 1) and used population genetics analyses to determine whether individuals from the Puget Sound/Georgia Basin region were genetically similar or different from individuals collected from the outer coasts of the U.S. and Canada.
Multiple analyses showed that Yelloweye Rockfish in Puget Sound and British Columbia, Canada were genetically different from coastal populations. Canary Rockfish showed no genetic differentiation (Fig. 2; Andrews et al. 2018). These results support the ESA designation status and the expansion of protected geographical boundaries for Yelloweye Rockfish. The findings also suggest Canary Rockfish in Puget Sound are not a 'discrete' population and may not meet the first ESA criterion.
The collaboration and cooperation among government agencies and fishing communities provided a framework for this research. The work led to two major management decisions:
- The delisting of Canary Rockfish from the federal endangered species list - a first for any marine fish species.
- Geographic expansion of population boundaries for Yelloweye Rockfish.
Can Rockfish Bycatch be Reduced in Popular Fisheries?
The ESA requires us to determine threats limiting the recovery and delisting of Yelloweye Rockfish (Sebastes ruberrimus) and Bocaccio (S. paucispinis). These species are listed as 'threatened' and 'endangered,' respectively, in Puget Sound, WA. One obvious threat to many fish populations is mortality from either targeted fishing or indirectly as bycatch in other fisheries.
The Washington Department of Fish & Wildlife (WDFW) implemented new regulations in 2010 that prohibited fishing for, retaining or possessing any rockfish species and prohibited all 'bottomfish' fishing deeper than 120 feet within the greater Puget Sound region. These rules significantly reduced the geographic scope of recreational fishing for some popular fisheries, including lingcod (Ophiodon elongatus).
Previously, charter boat captains and volunteer anglers told us that they rarely catch rockfish in the lingcod fishery when they use large, live bait (such as Pacific sanddab (Citharichthys sordidus) or kelp greenling (Hexagrammos decagrammus)). Our latest research allowed us to experimentally test a question that might address both the conservation of rockfish species and recreational fishing opportunities.
In this study, we tested whether catch-per-unit-effort of rockfish bycatch (Fig. 3) and targeted lingcod differed among commonly used bait types (live, frozen, and artificial; Fig. 4) in the Puget Sound lingcod fishery.
We chartered local recreational fishing charter captains and targeted lingcod across 12 sites in two regions of the discrete population segment at fishing depths from 26 – 425 feet (n=37 days). We used one of the three bait types at one of three sites each day, varying the bait type across sites on subsequent days.
We found rates of targeted lingcod catch were similar for each bait type. Further, using large, live bait types resulted in lower rockfish bycatch (Fig. 5). We caught 11 yelloweye rockfish, all at depths greater than 150 feet and with one of the 11 caught with live, large bait. This result indicated a risk of catching ESA-listed rockfish with live, large bait, but less risk than some other commonly used baits.
Understanding the magnitude and methods available to reduce bycatch in fisheries is an essential step in making decisions concerning the tradeoffs between conservation efforts of threatened species and impacts on fishing communities.
How Will We Know When Rockfish in Puget Sound Have Recovered?
The Rockfish Recovery Plan lays out specific criteria that must be met for each species to be down-listed from "endangered" to "threatened" and ultimately delisted from the Endangered Species Act. These criteria require surveys that count the number of individuals in Puget Sound and the Georgia Basin and analytical methods to calculate each population's current status and trend.
The first step is to develop a survey that can count these rare fish populations that live in complex, rocky habitats. The Washington Department of Fish & Wildlife has developed methods using a remotely-operated vehicle (ROV) to target these habitats (Fig. 6). They plan to run the survey once every five years.
The second step is to use the abundance estimates and size distribution of observed individuals from WDFW's ROV survey and life-history characteristics of each species to calculate status metrics used in data-poor stock assessments (Fig. 7).
The final step is to compare the outputs of steps 1 and 2 across multiple surveys over time to determine the trend of each species' population. We then compare the overall status and trend to the downlisting and delisting criteria in the Recovery Plan to determine how these populations are progressing toward management goals (Fig. 8).