Vermillion rockfish by Janna Nichols
There are 27 species of rockfish in the Salish Sea and some of these slow-growing, long-lived species can live to be over 100 years old. Over-fishing after restrictions on salmon fishing caused anglers to shift their fishing effort to rockfish, which caused populations of many rockfish species to crash. As you can imagine, recovery of a slow-growing species can be, well ... slow.
Throughout our history, the SeaDoc Society has been asking and answering important research questions about rockfish.
Are seals eating rockfish?
Since the 1970s, harbor seal populations have exploded nearly tenfold in the Salish Sea. At the same time, many rockfish populations were declining. Some anglers blame the seals. But how much of an impact do seals really have?
SeaDoc thought this question was one we could address with good science so we funded a project to collect almost 1,000 samples of seal scat in the San Juan Islands. The samples were washed, dried, and examined. It turns out 60% of the seals' diet was herring, followed by salmon, pollock, and cod-like fish. In total, the seals ate 35 different species of fish. Only 3% of the samples contained rockfish bones.
But that didn't fully answer the question. In the second year of the study, almost 12% of samples contained rockfish bones, particularly in the winter when there were fewer salmon around. Given the number of seals in the Salish Sea, this could be important for rockfish recovery. But the solution is not as simple as getting rid of seals. Seals also eat dogfish, which can be a major predator of rockfish. So if we got rid of seals, we might just have more dogfish and not move the needle on rockfish recovery. On the other hand, healthy herring and salmon stocks will reduce the pressure that seals put on rockfish so rockfish recovery is really tied to salmon recovery and herring recovery!
This study reminded us how interconnected the food web is, and how much the recovery of any particular species depends on the recovery of the entire ecosystem.
What areas need to be protected for rockfish to recover?
It seems reasonably obvious to say that if we want rockfish to recover, we have to protect the habitat where they live. Since the older and larger a rockfish grows, the more young she has and probably for some species, the better able to young are to survive, we especially want to create safe locations where old female rockfish can survive and reproduce. This might take the form of Marine Reserves, where fishing (or certain types of fishing) is restricted. But does that really help?
SeaDoc has conducted several research projects on the efficacy of marine protected areas and found that mandatory reserves seem to work better than voluntary no-take zones, especially if the voluntary reserves are small (and can be fished out by unscrupulous people). In general, larger protected areas usually work better than small ones.
In 2007 we funded an innovative project that aimed to try to answer the question of how large a reserve would be needed to protect Brown Rockfish populations. The study, described in detail here, used genetic markers to determine where rockfish from one marine reserve ended up later in their lifespans. The evidence suggests that juvenile rockfish disperse fairly widely meaning that for reserves to work, we likely need a network of protected areas that are close enough to be connected by dispersal of the young.
How can we find and protect rockfish habitats?
In order to protect rockfish habitat, you need to know where it is. As you might guess from their common name, rockfish like rocks. They like to inhabit boulder piles, rock faces, and other rough and rugged underwater habitat.
For the past decade, SeaDoc has been collaborating with marine geologist Gary Greene to create underwater maps of the Salish Sea. (Greene's Tombolo mapping project is now part of SeaDoc's operation.)
Using multibeam bathymetry and sophisticated mapping technology, Greene and his team have mapped significant portions of the Salish Sea. These maps have allowed researchers to hone in on rocky outcroppings that provide potential rockfish habitat, which has accelerated the work of many researchers. Additionally, the maps have revealed other habitat areas with large impacts on the Salish Sea food web, such as the immense sand wave fields that provide protection for millions of Sand Lance. (Sand Lance are a crucial food source for many marine birds.)
Bringing people together to improve rockfish recovery
Many organizations and individuals are working on rockfish recovery, on both sides of the border. But sometimes that means that effort is duplicated or important research questions are going unanswered. One obvious solution is to bring all the researchers together to discuss their work, share ideas, and develop a research agenda that will help more researchers find money to do important projects.
But it's not always so simple. For example, when 3 species of rockfish were listed as Endangered under the Federal Endangered Species Act, NOAA Fisheries needed to come up with a management plan, and wanted to bring together all the scientists working on rockfish recovery. But due to funding constraints, they weren't able to include Canadian scientists. So SeaDoc stepped in to co-sponsor the workshop and made it possible for Canadian scientists to be represented, which ended up being an important part of the conference. Like almost all the issues facing the Salish Sea, rockfish recovery is not limited to just one side of the border.
SeaDoc's involvement in complex issues
Although SeaDoc is a relatively small organization, our ecosystem-level focus and our base of private support allows us to identify important knowledge gaps - such as the location of rockfish habitat, or the dispersal of rockfish populations - and move quickly to fill them. The issue of rockfish recovery is too big for any one organization to solve, but SeaDoc has provided crucial tools and scientific information that is aiding many of the groups working on this complex issue.
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