Twenty-five years after several rockfish species were severely depleted, stock assessment models predict 90 years or more before meaningful recovery occurs for long-lived species such as quillback rockfish.
Author: Laura Borden, Howe Sound Research and Conservation, Coastal Ocean Research Institute, an Ocean Wise initiative
Reviewer: Jeff Marliave, Senior Scientist, Howe Sound Research and Conservation, Coastal Ocean Research Institute, an Ocean Wise initiative
Banner Photo Credit: Lee Newman
Rockfish populations along the B.C. south coast remain depressed since a record low in the 1990s, following high levels of harvest from the 1970s through the 1990s. Quillback rockfish, an inshore rockfish species listed as threatened by COSEWIC in 2009 and the focus of this article, have shown year-to-year variation in abundance both in inside waters of the Strait of Georgia and in outside waters of the West Coast of Vancouver Island since the mid-1990s (Figure 1 and 2). Longline surveys conducted by Fisheries and Oceans Canada (DFO) (some in collaboration with industry) also show year-to-year variation in the abundance of quillback rockfish in inside and outside waters from 2003 to 2016. Only in areas on British Columbia’s north coast are indices of quillback rockfish populations showing a slight positive trend.
Quillback (and copper) rockfish were prime targets in the live market fishery of the 1980s, which led to their serial depletion on a reef-by-reef basis. As quillback rockfish are one of the longest-lived rockfish species, recovery of this species may take decades of favourable environmental conditions coinciding with sufficient reproductive-age adults. An example of these two parameters coinciding occurred during a climate regime between 2000 and 2010. During this period, observed quillback rockfish abundance was higher in inside waters than either before or after (Figure 2), primarily due to a high survival rate for young of the year rockfish in multiple years during that climate regime. Abundant year classes do occur from time to time – we have received reports that 2016 was an exceptional year class for some rockfish species along large stretches of the Pacific Coast in outside waters. Perhaps related to this, high abundances of young yellowtail rockfish were observed in 2017 in inside waters, during Ocean Wise Rockfish Abundance Surveys.
Why is it important?
Thirty-seven species of rockfishes occur in British Columbia waters. Some species are only regionally abundant such as canary rockfish, China rockfish and deacon rockfish that predominantly occur on the outer coast. Some rockfishes have quite small home ranges and high site fidelity, and many are long-lived species – quillback and yelloweye rockfishes live approximately a century – making them highly susceptible to overfishing. As populations were severely depleted just 25 years ago, detectable population recovery may still be decades away.
First Nations Connections
Quillback rockfish and other species of rockfish are an important component of Coastal First Nations’ diets, as they provide food security year-round. An archeological study conducted in Barkley Sound on the west coast of Vancouver Island recovered and examined skeletal remains of rockfish species, indicating regular use by First Nations communities for over 1,500 years. In three communities in Barkley Sound, remains of rockfish species were found in 96 percent of excavation unit assemblages. Further supporting the importance of rockfish species to Coastal First Nations, a meta-analysis of 40 years’ worth of zooarcheological data from this coast found widespread inclusion of rockfish in First Nations diets.
Young rockfish abundance takes off in 2016
2016 marked an exceptional year class for some rockfish species. An unprecedented abundance of young of the year was documented by the diving community along the Pacific coast from Neah Bay, Washington to the central coast of British Columbia. This booming year class highlights what can occur when the necessary environmental and food conditions are just right. Records of young rockfish counted during dive surveys based out of the Hakai Institute on B.C.’s central coast demonstrate a spike in abundance in 2016, such that counts more than doubled what had been observed in any of the three previous years.
What is the current status?
Long-term abundance records for quillback rockfish indicate little recovery since overfishing into the 1990s. Roving-diver biodiversity surveys from 1993 to 2017 show an average abundance (including adults, juveniles and young of the year) of quillback rockfish of 10 and 16 individuals per reef site for the west coast of Vancouver Island and Strait of Georgia regions, respectively (Figure 2).
A notable increase in observations of quillback rockfish in the Strait of Georgia occurred between 2002 and 2011, especially observations of juvenile and young of the year (Figure 2). This decade-long increase began shortly after the millennial climate regime shift and ended in about 2011. A climate regime shift for 2011 has been proposed, based in part on the period of increase observed for quillback rockfish, and in part on additional long-term biodiversity data. Climate regimes are characterized by either warm or cold patterns in sea surface temperature (tracked by the National Oceanic and Atmospheric Administration’s (NOAA) Oceanic Niño Index) and can relate to trends in biodiversity.
Limited years of data from an age-based survey of rockfish populations conducted by the Coastal Ocean Research Institute, an initiative of Ocean Wise, and citizen scientists indicate that quillback rockfish abundance in both the Strait of Georgia and the west coast of Vancouver Island has not changed significantly in the last few years (Figure 3). Both areas show evidence of low overall recruitment (indicated by low numbers of young of the year) and a predominantly adult population.
The most recent stock assessment for quillback rockfish, from 2011, concludes that both outside and inside stocks appear to be in the “cautious” zone using DFO’s Precautionary Approach and Fisheries Reference Points framework and discusses recovery potential as estimated by the stock assessment model. Assuming catches occur at the level of 2017 total allowable catch (TAC) – 147 tonnes outside and 22 tonnes inside – for 90 years hence, outside quillback stocks have about a 75 percent chance of recovering to the “healthy” zone, and inside stocks have about an 88 percent chance of similar recovery. If we are looking for 95 percent probability of recovery to the “healthy” zone in 90 years, the model estimates that catch must be lower than 60 tonnes outside and nil in inside waters.
What can you do?
Individual and Organization Actions:
- Participate in citizen science SCUBA surveys.
- Report illegal fishing practices to DFO 604-666-3500 (1-800-465-4336).
- Follow posted fishing regulations.
Government Actions and Policy:
- Commit more resources to understanding the effects of RCAs. For example, monitor rockfish populations in RCAs with suitable habitat.
- Simplify regulations in RCAs.
- Increase public education and awareness of closures to commercial and recreational fisheries, and the status of rockfish populations.