After a decline in lingcod population triggered restrictions on commercial and recreational fisheries, indices show no clear trends in populations. Catches are quite restricted in the Strait of Georgia and decreasing elsewhere, even though these outside stocks are assessed as healthy.
Authors: Laura Borden and Karin Bodtker, Coastal Ocean Research Institute, an Ocean Wise initiative
Reviewers: Jeff Marliave, Senior Scientist, Coastal Ocean Research Institute, an Ocean Wise initiative; Dana Haggarty, Research Biologist,Pacific Biological Station, Fisheries and Oceans Canada
Banner Photo Credit: Jenn Burt
Lingcod in British Columbia experienced extensive fishing from the 1950s through the 1990s. Current commercial catches in outside waters (i.e., north and west of Vancouver Island, Figure 1) are about one sixth of the historical peak (Figure 2). In 2011, stock status in outside waters was assessed as healthy, even though estimated biomass was lower than in any previous year. Annual commercial catch in the outside waters has declined by about 25 percent since this last assessment (Figure 2).
Fishing for lingcod in the Strait of Georgia (SoG) (Figure 1) began in the 1800s but catches were not recorded separately from other species until 1927. Catch statistics show that lingcod were fished heavily in the strait in the early 20th century, with a peak of over 4,000 tonnes in 1944 (Figure 3). One reconstruction suggests the SoG stocks reached a historic low in 1991, to an estimated 2.6 percent of the biomass in 1951.
These stocks were recently assessed as being in the critical to cautious zone, despite commercial fishing restrictions that were put in place in 1990 and a prohibition of recreational retention between 2002 and 2006. Currently, most of the inside waters are closed to commercial lingcod retention, therefore reported catch, which is minimal (Figure 3), comes from small areas that are open or is non-targeted (i.e., bycatch). Retention by recreational fisheries is restricted through area and seasonal closures, size restrictions (65 cm), and daily and annual bag limits. Both 2005 and 2014 assessments of SoG stocks conclude that lingcod spawning biomass in the Strait of Georgia is increasing, albeit slowly.
Why is it important?
Lingcod range from Northern California to the Aleutian Islands in Alaska and are unique to this coast of North America. They are an ecologically important top predator on rocky reefs throughout their range, consuming smaller fish such as hake, herring, rockfish and other small fishes. Lingcod rely on the nooks and crannies around large boulders or crevices with good water flow for successful spawning during the winter months. Research has shown that male lingcod, who actively guard their egg masses, return to the same spawning locations year after year.
Lingcod have a long history of commercial and recreational exploitation in B.C. The commercial fishery for lingcod was ranked fourth in importance throughout the first half of the 20th century. This status as a top commercial fishery has waned, but the sport fishery still targets and prizes lingcod. Fishing is one of the main threats to lingcod populations, likely including illegal poaching. In addition, populations of sea lions and harbour seals, both significant predators of non-juvenile lingcod, are increasing in abundance. Large numbers of Steller sea lions are known to feed in the Strait of Georgia in winter and early summer. The magnitude of the threat that these predators pose to lingcod recovery is not well understood. For example, analyses of harbor seal scat in Howe Sound have not been conducted since the 1980s, but scat studies could provide clarity on predation rates of local lingcod.
What is the current status?
Data used to estimate stock status come from trawl surveys (for outside stocks only) and from records of commercial and recreational catch. Lingcod biomass indices developed from groundfish trawl survey data (2003-2016) show high year-to-year variability, with an overall decline except in the region to the west of Haida Gwaii (Figure 4, indices and survey areas).
Additional surveys using hook and line gear are used for research and to monitor status, but to date have not been used in the formal stock assessments. These surveys are named International Pacific Halibut Commission (IPHC), Inshore Rockfish North (IRF North), Inshore Rockfish South (IRF South), Pacific Halibut Management Association North (PHMA North), and Pacific Halibut Management Association South (PHMA South). Biomass indices from these surveys also show great year-to-year variability, but show overall increases in inside waters (e.g., IRF North and South) and decreases in outside areas (e.g., PHMA North and South surveys, Figure 5 indices and survey areas). The declining trend in the PHMA South survey was noted in the Fisheries and Oceans Canada (DFO) State of the Pacific Ocean report for 2016, as was the increasing trend illustrated in the northern inside waters of Johnstone Strait (IRF North survey, Figure 5).
Egg mass surveys, undertaken by citizen scientists and organized by the Coastal Ocean Research Institute, track the reproductive population of lingcod by recording a count of egg masses observed per hour. Data from these surveys also illustrate variability, but show no overall trend since 1996. Three areas have been surveyed including the Strait of Georgia, northeast Vancouver Island, and the west coast of Vancouver Island. Some sub-regions such as Howe Sound did show an increase in spawning lingcod abundance, according to this survey, at the turn of the millennium.
The spawning population survey data also show no long-term trend in the abundance of large egg masses, belonging to older lingcod and contributing disproportionately more to future generations, except possibly in the northeast Vancouver Island area, determined only by visual inspection. This potentially corroborates an increasing trend illustrated in the Inshore Rockfish North survey in the northern inside waters of Johnstone Strait (Figure 5).
We report on available data, but trends in indices from any of these surveys are not definitive of lingcod stock status, as many additional factors can influence the amount of lingcod caught in both trawl and longline surveys, or observed at scuba depths. For example, changing climatic conditions could be affecting the spatial or depth distribution of these populations. However, trends that suggest increases in some areas and declines in other areas are not surprising, given that lingcod tend to have small home ranges. It may be beneficial to examine population status and trends on a finer spatial scale, looking specifically at sub-regions of inside waters and outside waters to better understand local populations.
What can you do?
Individual and Organization Actions:
- Participate in citizen science SCUBA surveys.
- Report illegal fishing practices to DFO (604-666-3500).
- Follow posted fishing regulations.
Government Actions and Policy:
- Designate more resources to effective monitoring and enforcement of fishing closures.
- Increase public awareness of fishing regulations and closures for commercial and recreational fisheries.
Undertake scat studies of lingcod predators (i.e., seals and sea lions) in areas where predators have increased and lingcod populations remain depressed.
- Consider undertaking stock assessments for lingcod at a finer spatial scale.