Rockfish and other bottomfish

This past week (June 28 & 29, 2011) SeaDoc co-hosted a Rockfish Recovery Workshop in Seattle with the State Department of Wildlife and NOAA Fisheries.

Nearly 100 scientists, fisheries managers, fishers and SCUBA divers attended the 2-day workshop to discuss the current state of knowledge on rockfish and to identify future needs related to recovering depleted rockfish populations in the Salish Sea.

There are 28 species of rockfish in the Salish Sea. Thirteen (13) are listed as species of concern and recently 3 species were listed under the US Endangered Species Act.

In addition to helping organize the workshop, SeaDoc also helped bring in Canadians to share their perspective on what has and has not worked with rockfish recovery on the other side of the border.

A lot of the research SeaDoc funded over the last 10 years was presented and plans were laid for moving rockfish recovery forward. The meeting proceedings will be published soon and will be available here on the SeaDoc website.

In the meantime, here's a recap:

(Please note that this summary is taken from my notes and if there are errors or misstatements they are mine, not the researchers/presenters! -Joe T.)

Historical Context Session

Wayne Palsson spoke on the biology and assessment of rockfishes in Puget Sound. Rockfishes are a diverse group of species with different life histories. They require various habitat during different life stages. They are adapted for slow growth, long survival, late maturity, low natural mortality rates, and high habitat fidelity. These are all factors that make recovery tough. There's a lack of long-term data that makes it hard to create conventional age-structure population models and biomass dynamic models. 

Chris Harvey reviewed the ecological history of rockfish exploitation in Puget Sound. Rockfish bones have been found in middens dating back 1,500 years. Much of the fishing pressure on rockfish began after the Boldt decision in 1974, which required that harvests in Puget Sound be coequally managed by the State government and the Treaty Tribes of Washington. It's also been influenced by demographic trends and by the promotion of the fishery by State government. (Unfortunately, as covered in Wayne Palsson's talk, it wasn't until 1982 that scientists learned that rockfish were generally 2 to 3 times longer lived than they'd thought, which meant the existing population models were not accurate.) By the time management efforts were deemed necessary, the greatest harvests had already occurred. 

Anne Beaudreau discussed her work to reconstruct historical trends in rockfish abundance. The lack of data on historical populations of rockfish is a major barrier to developing sustainable fisheries. Beaudreau and colleagues interviewed 101 individuals ranging in age from 24 to 90 years to try to derive trends in the abundance of rockfish from 1940 to the present. Of particular interest was the evidence of "shifting baselines." To a statistically significant degree, each age group of respondents interpreted the conditions at the beginning of their awareness as "abundant" and saw declines from there, but what was "declining" to an older person was "abundant" to a younger person. 

Benthic Habitat Surveys/Rockfish Abundance Estimates Session

Gary Greene presented the Salish Sea sea floor mapping project, which has produced bathymetric and habitat maps of the San Juan Islands area. Rockfish prefer particular habitat types, and the multibeam echosounders used by Greene and his colleagues allows these potential habitat areas to be identified. (Other participants were very interested in having these maps for other areas in the Salish Sea.

Bob Pacunski spoke on work to use non-lethal methods to survey rockfish populations. Traditional trawl or long-line sampling results in fish mortality, but using a small remotely-operated vehicle has been shown to be effective at providing population surveys. 

Stressors Session

Joan Drinkwin of the Northwest Straits Foundation spoke on the threat posed to rockfish by derelict fishing gear, including both nets and traps. The Northwest Straits Initiative has removed 3,860 nets from Puget Sound, all at less than 105 feet deep. There are 950 shallow-water nets still in the water, and at least 70 in deeper water. Based on studies of net mortality by the SeaDoc Society, approximately 1,600 rockfish per year are captured and killed in derelict nets each year in the United States portion of the Salish Sea. 

...More coming soon...

Many of us made New Year's resolutions to lose weight. And those of us of a certain age bemoan the fact that humans hit our biological primes well before middle age.

But did you know that it's much different for fish? Take, for example, our own rockfish. Nearly 30 species of rockfish live in the Salish Sea, and some of them don't become sexually mature until they're 20 years old – that's two decades of avoiding hungry mouths, baited hooks and nets until they can even begin to breed. Once they do, though, the female rockfish gives birth to live young and we believe she continues to reproduce her entire life span, which for some species can be more than 100 years!

Independent of the recent Federal listing of 3 rockfish species, Washington State is working on their rockfish recovery plan. Today SeaDoc submitted comments on the revised draft Environmental Impact Statement.

While most of the recovery plan is good, the State is still proposing that hatchery production and the use of artificial habitat be used as part of the recovery strategy. SeaDoc feels that hatcheries and artifical habitat are not good ideas.

PDFs:

Read our comments

Read the WDFW draft rockfish EIS

Comments must be received by 5pm on May 21, 2010. Visit the Washington Dept of Fish and Wildlife for more information.

Harbor seal populations have exploded nearly tenfold in the Salish Sea since the 1970s, while at the same time many rockfish species have plummeted. Some fishermen blame that on the increase in hungry seals. But coincidence is not science. So who ya gonna call?
 
SeaDoc-funded scientists rolled up their sleeves and collected almost 1,000 samples of seal scat in the San Juan Islands. Detailed analysis of these samples revealed that herring make up nearly 60% of these harbor seals' diets, with their next favorite meals being salmon, pollock and cod-like fish. The seal's total menu, though, was surprisingly diverse, with seals chowing down on at least 35 species of fish! Still, through the entire first year of the study, less than 3% of samples contained rockfish bones. Case closed? Not so fast...
 
In the second year, 12% of the samples contained rockfish remains, particularly in the winter when there are fewer salmon locally. With all the seals in the Salish Sea, those numbers could impact rockfish recovery. That doesn't mean, however, that we should start controlling seal populations: this study showed seals also have a taste for dogfish, another major fish predator. So fewer seals could mean more dogfish. The real answer is to remember that all parts of our ecosystem are tightly intertwined. Rockfish recovery depends upon ecosystem recovery, including salmon recovery, herring recovery and so on around the Sea.

More information on this topic:

• The original report on this study (so you can see what we've learned since the first round)
• The Puget Sound Partnership's resource page on rockfish.
• SeaDoc's comments on the proposed (12/2009) rockfish conservation plan by the WA Dept of Fish & Wildlife.
• All the info on our site about rockfish (automatic search)
• All the info on the site about predator/prey relationships (automatic search)

(You can do these last two searches yourself by choosing "browse by species" or "browse by issue" from the Salish Sea menu at left.)

Here's a video (aimed at kids) that gives a behind-the-scenes look at how this kind of research is done.