Ocean Outbreak: Confronting the Rising Tide of Marine Disease (Book Review)

Ask any ocean lover to name the biggest threats to ocean conservation and you’ll get a list so long it will make you uncomfortable: derelict fishing gear, increasing underwater noise, invasive species, ocean acidification, overharvest, plastics, toxins, warming water, and so on.

What you probably won’t hear is the word disease—not because the agents of disease are microscopic and out of sight, but because we know so little about how they affect the marine environment. Most people have never thought of parasites and pathogens as agents of change or important ocean stressors.

Ensuring the Future of Pacific Herring in the Salish Sea

Ensuring the Future of Pacific Herring in the Salish Sea

Herring are a small fish that play a big role up the food chain, and at the moment scientists don’t know nearly enough about their health status in the Salish Sea. That’s why SeaDoc funded a study that helped bring many top herring experts together for the first time–a crucial first step in ensuring their future.  

The team recently published a report, “Assessment and Management of Pacific Herring in the Salish Sea: Conserving and Recovering a Culturally Significant and Ecologically Critical Component of the Food Web,” which included the creation of a model that simulated how herring populations respond to key environmental stressors under various scenarios.

Salmon Escape: What Does the Science Say?

By Joe Gaydos

On August 19 and 20, a net pen owned by Cooke Aquaculture Pacific collapsed, releasing an undetermined number (estimates range from 4, 000 to 185,000) of the 305,000 Atlantic salmon being raised there into the waters around Cypress Island, just northwest of Anacortes, Washington.

In a region where vast amounts of money and effort have been spent attempting to restore wild salmon runs, this mass escape of non-native fish has caused a public uproar. How could this happen? Will the Atlantic salmon spread disease to wild fish? Will they outcompete native salmon for food or freshwater spawning habitat?

To try and answer the questions, it’s valuable to look at the established science. Unfortunately, salmon spills like this are not new events in the Pacific Northwest.

People have been farming Atlantic salmon in Washington since 1982, and in British Columbia since 1985 (McKinnell and Thompson, 1997). Despite assurances from the aquaculture industry, wherever there are fish farmed in sea pens there are escapes.

In fact, on July 2, 1996 high tidal flows destroyed seven net pens at an Atlantic salmon farm near Cypress Island, releasing or killing 101,000 Atlantic salmon (McKinnell and Thompson, 1997). Sound familiar? The lessons from that and other releases should inform us about the risk that farmed Atlantic salmon pose for the Salish Sea's five species of native salmon.

The first concern is the potential for released farmed salmon to transmit disease to wild salmon. Farmed Atlantic salmon can carry viruses, bacteria and parasites like sea lice that can infect wild salmon (e.g., Jones et al., 2015). The release of thousands of salmon that were actively experiencing a disease outbreak could have huge ramifications for wild salmon.

In Washington State, all public and private growers of salmon, including Atlantic salmon hatchery operators, are required to adhere to strict disease control polices (Waknitz et al., 2003). While we have not seen data on the health or disease status of the released Atlantic salmon, it was reported that they were treated for a bacterial infection called yellow mouth in July 2016 but were believed to be disease-free at the time they escaped.

Without detailed disease testing data it is difficult to know what the potential for disease transmission could be in this most recent release. An evaluation of the risk of disease transmission from farmed Atlantic salmon to wild Pacific salmon conducted over a decade ago (Nash 2003) classified the risk as low due to existing disease testing protocols and the State's prohibition of bringing new Atlantic salmon stocks or eggs into Washington (which limits new diseases from entering).

As to whether released farmed salmon will compete with native salmon for food and breeding or spawning space, studies (Jonsson and Jonsson, 2006) have shown that while their performance and reproductive success in nature vary, farmed Atlantic salmon often are outcompeted by wild salmon of similar size.

Between 1987 and 1996, 10,609 Atlantic salmon were caught in the North Pacific representing 4.2% of the total number reported to have escaped since Atlantic salmon farming began in Washington and British Columbia (255,554 escapees reported; McKinnell and Thompson, 1997). Interestingly, this includes Atlantic salmon caught in Alaska, even though Alaska does not allow Atlantic salmon farming, proving that the fish are capable of surviving and moving great distances after escaping.

Of the Atlantic salmon caught during that time period, stomachs were examined in 813 animals. Empty stomachs occurred in almost 77% of ocean-caught Atlantic salmon and 62% of those caught in freshwater. Washington Department of Fish and Wildlife has examined the stomach contents of about a dozen of the recently escaped Atlantic salmon and all of their stomachs have been empty. Additionally researchers and volunteers from the non-profit KWIAHT dissected 31 Atlantic salmon caught in Watmough Bight last week and found empty stomachs with the exception of two fish that each had one small mussel shell and a few crumbs of fish chow pellets. This suggests that while released farmed Atlantic salmon will compete with wild salmon for food, many also don't make the transition from being fed pellets in farms to catching and eating wild food. For those that do, though, stonefly nymphs found in the stomachs of Atlantic salmon caught in the Salmon River (Vancouver Island) suggest that escaped Atlantic salmon also can be predators in freshwater as well as in ocean ecosystems (McKinnell and Thompson, 1997).

Although the probability is low, escaped adult Atlantic salmon have the potential to colonize and exist as self-sustaining introduced species. In 1998, scientists captured twelve juvenile Atlantic salmon (and observed, but did not capture another 28) in the Tsitika River on Vancouver Island (Volpe et al., 2000). Genetic analysis confirmed that these were Atlantic salmon that were the products of natural spawning by released Atlantic salmon. More recent survey work and modeling looking at Atlantic salmon use of freshwater streams in British Columbia showed that 97 % of streams in British Columbia with high native salmon diversity were occupied by Atlantic salmon and that Atlantic salmon can occupy these rivers for multiple years (Fisher et al., 2014). Colonization can occur.

The only potential positive from this large release of Atlantic salmon is that these farm-raised fish should serve as easy prey for seals, sea lions and eagles, maybe taking some predation pressure off wild salmon.

On balance, though, the science looking at past net pen releases of Atlantic salmon in this region suggests that there can be negative impacts to native salmon including disease transmission, competition for food and breeding habitat, and the potential for long-term establishment of an introduced Atlantic salmon run.

Science informs decisions, it does not set public policy: the people and their representatives do. So while the science does not suggest that this spill will likely be catastrophic to wild salmon, in looking at the public reaction to this net pen release and the outcry against Cook Aquaculture Pacific, it seems evident that the people of the Salish Sea value native salmon runs more than they do the salmon farming industry.

The message from the public appears clear: With the billions of dollars we’ve invested to protect and recover native wild Pacific salmon, any introduced risk like farmed Atlantic salmon is unacceptable.

For daily updates, please visit the Washington Department of Natural Resources website on this incident.

To report your catch of Atlantic salmon or see where these escaped farm fish are being caught, visit the Washington Department of Fish and Wildlife's Catch Map.

Literature cited:

Fisher, AC, JP Volpe, JT Fisher. 2014. Occupancy dynamics of escaped farmed Atlantic salmon in Canadian Pacific coastal salmon streams: implications for sustained invasions. Biological Invasions 16:2137-2146.  doi 10.1007/s10530-014-0653-x

Jones, SRM, DW Bruno, L Madsen, EJ Peeler. 2015. Disease management mitigates risk of pathogen transmission for maricultured salmonids. Aquaculture Environment Interactions 6:119-134. doi 10.3354/aei00121

Jonsson B, N Jonsson. 2006. Cultured Atlantic salmon in nature: a review of their ecology and interaction with wild fish. ICES Journal of Marine Science 63:1162-1181. doi 10.1016/j.icesjms.2006.03.004

McKinnell S and AJ Thomson. 1997. Recent events concerning Atlantic salmon escapees in the Pacific. ICES Journal of Marine Science 54:1121-1125.

Nash, CE. 2003. Interactions of Atlantic salmon in the Pacific Northwest VI. A synopsis of the risk and uncertainty. Fisheries Research 62:339-347.

Volpe JP, EB Taylor, DW Rimmer, BW Glickman. 2000. Evidence of natural reproduction of aquaculture-escaped Atlantic salmon in a coastal British Columbia River. Conservation Biology 14:899-903.

Waknitz FW, RN Iwamoto, MS Strom. 2003. Interactions of Atlantic salmon in the Pacific Northwest IV. Impacts on the local ecosystems. Fisheries Research 62:307-328.

Note: if you would like to read any of these peer-reviewed papers and do not have access to them, please contact SeaDoc.



Banner photo: Farmed Atlantic salmon caught by a fisherman after the Cooke Aquaculture Pacific incident. Courtesy of Washington Department of Fish and Wildlife.

Taking Care of the Little Things

By Bob Friel

Everybody loves the Salish Sea’s killer whales, playful porpoise, and puppy-like seals. Birders flock here to see such feathered favorites as rhinoceros auklets, tufted puffins, and marbled murrelets. And no fish anywhere is as exalted as our Chinook, the king salmon, appreciated as sport fish, table fare, and cultural icon.

But where’s the love for the sand lance? Who here is a herring hugger?

Forage fish are the Rodney Dangerfields of the sea—they get no respect. Even that catchall name for the many different species of small schooling fish suggests they exist only to serve as self-propelled snacks. However, without these little fish that feed at the base of the food web, converting plankton into silvery packets of energy, there wouldn’t be any of those other more charismatic critters. No auklets, no puffins, and no king salmon. And without king salmon, of course, the Southern Resident Killer Whales disappear.

It’s impossible to exaggerate the importance of forage fish to the overall health of the Salish Sea. Unfortunately the research and, where needed, recovery work on these vital species hasn’t been commensurate with their value. So SeaDoc is investing in forage fish by funding two new projects, one on sand lance and the other on herring.

With everything from seabirds to sea lions hunting them, Pacific sand lance (Ammodytes personatus) have evolved an ingenious survival strategy. Whenever they’re not grazing on plankton in the water column, they tuck themselves into the sandy seabed to hide from predators and wait for their next feeding opportunity.

We know that Pacific sand lance nourish myriad crucial Salish Sea species, and a recent Northwest Straits Initiative / SeaDoc study showed smaller sand lance are widely distributed in our near shore waters year round, with population peaks in the summer. But we still don’t know the answers to some basic questions about these fascinating little fish, such as: Where exactly do they like to hide? How many of them are there? And, are their populations stable?

Now, we’re funding a new project that will use underwater video and a bottom-biting oceanographic tool called a Van Veen Sampler to ascertain the exact types of sea floor where the sand lance prefer to bury (too silty and they can’t breathe; too gravelly and they can injure themselves while tunneling). Co-investigators Drs. Cliff Robinson (Pacific Wildlife Foundation / University of Victoria) and Doug Bertram (Environment and Climate Change Canada) and their team will precisely map those habitats, build an improved model for predicting seafloor use by sand lance, and re-sample study sites monthly to look at population health and seasonal variability.

Compared to our knowledge base on sand lance, we know quite a bit about Salish Sea herring. As the foundational forage fish—the energy source that spins a huge part of our food web—healthy herring populations are considered so critical that the Puget Sound Partnership lists them as one of our “vital signs.” Simply checking the dwindling numbers of many herring stocks on the Washington State side of the Salish Sea, tells you that the ecosystem is in trouble.

The herring stock that spawns at Cherry Point, site of the state’s largest oil refinery, was once the most prolific in all of Puget Sound. Since 1973, the Cherry Point population has crashed by more than 93 percent. While this stock and others on the U.S. side are faltering, in British Columbia's Strait of Georgia they’re currently booming. With your support, our research is designed to find out reasons why some stocks are hurting and how to recover them as soon as possible.

Helping herring will never be as sexy as salmon conservation, but it’s every bit as important to the health of our ecosystem. So SeaDoc is jumpstarting the recovery process for Puget Sound herring by funding a joint US / Canadian team co-led by Drs. Tessa Francis (Puget Sound Institute, UW Tacoma) and Dayv Lowry (WA Department of Fish and Wildlife) that will act as the nexus for relevant data and expertise. This project will determine the specific threats harming the southern herring populations, assess all of the stocks, and evaluate the state of the science, policies, and ongoing recovery efforts in order to ultimately produce a comprehensive Salish Sea herring conservation and management plan.

Thanks to your support, both new projects continue the SeaDoc Society’s mission to provide the science that’s helping to heal our Salish Sea.

This holiday season, show some love to the lowly forage fish. Go ahead: hug a herring.



Banner photo: Rhinocerus auklet with sand lance. Courtesy of Phil Green, from The Nature Conservancy.

When it comes to at-risk species, we're bailing a leaky boat

By Bob Friel

Every two years, SeaDoc scientists catalog all of the Salish Sea species that are listed as endangered or otherwise considered at-risk by the four governmental bodies charged with protecting the inland sea’s wildlife. Before we launched our biennial study back in 2002, no one was comparing the lists maintained at the U.S. federal level (via NOAA and the US Fish and Wildlife Service), locally by Washington State agencies, and across the border by both the province of British Columbia and the Canadian federal government.

Surprisingly, each of the four lists is very different, making SeaDoc’s Marine Species at Risk compilation an invaluable tool for ecosystem managers on both sides of the border. According to Cecilia Wong and Michael Rylko of Environment Canada and the US Environmental Protection Agency, respectively, and co-chairs of the Transboundary Ecosystem Indicators Project, SeaDoc’s work “provides a unique, long-term perspective on the Salish Sea, and fosters multilateral collaboration toward restoration and conservation.”

Since our study looks at the status of fish, mammals, birds, and invertebrates throughout the Salish Sea, top to bottom, it offers a “state of the sea” view on the entire ecosystem relative to recovery efforts. Unfortunately, our most recent report shows the continuation of a troubling trend.

First the good news: Five natives were removed from the list, including Pacific ocean perch, the Georgia Strait population of coho salmon, the belted kingfisher, cackling goose, and snowy owl. The bad news is that over the last two years, 12 more animals, including the longfin smelt, gooseneck barnacle, and black-legged kittiwake, were added to the list, bringing the total to 125 species of concern. Disturbingly, this is the eighth straight study with more species hitting the list than graduating off it. As SeaDoc co-authors Jacquelyn Zier and Joe Gaydos conclude, this negative movement “suggests ecosystem recovery efforts are being outpaced by ecosystem decay.”

Listing species does bring the animals and their critical habitats more attention, but when it comes to restoring the overall health of the Salish Sea, these ever-expanding lists show that we’re still trying to bail out a leaking boat.

To see the Health of the Salish Sea Report where the SeaDoc Society’s Marine Species at Risk study is used by the U.S. Environmental Protection Agency and Environment Canada as a transboundary indicator, visit the EPA website.



Banner photo: while the Georgia Strait population of Coho salmon has graduated from our Species At Risk list, 12 more species have been added. Courtesy of U.S. FWS/Pacific Region.

Scientists who showed how copper damages salmon’s sense of smell receive prestigious award

It’s always beautiful when scientific discovery leads directly to concrete changes in environmental policy.

Such was the case with a team of scientists who will be honored by the SeaDoc Society on Friday for having demonstrated how copper damages salmon’s sense of smell. Their work led to legislation that removed copper from car brake pads in Washington State.

The team, led by NOAA scientists Drs. Jenifer McIntyre, David Baldwin, and Nathaniel Scholz, helped pave the way for the legislation, which will benefit salmon recovery by reducing the loadings of toxic metals to the Salish Sea by hundreds of thousands of pounds each year.

The award will be presented at the Salish Sea Ecosystem Conference, which starts April 13 in Vancouver, B.C. Close to 1,000 scientists and conservationists from both sides of the U.S.-Canada border are expected to convene for three days to discuss recovery of the Salish Sea.

Copper is a major constituent of conventional brake pads and is released with other metals in a fine dusting each time a car slows. This metal is then washed into streams, rivers and the Salish Sea by rainfall. Copper has long been known to disrupt the sense of smell in fish, but the consequences of transient, low-level copper exposures for salmon were unknown when the NOAA team began studying this problem in the early 2000s.

The prize-winning scientists and their colleagues first showed that copper blocks salmon's ability to smell well during the short length of a typical stormwater runoff event.

The team then demonstrated that copper-caused damage to the olfactory (smell) system actually made juvenile salmon more vulnerable to predators. Salmon attacked by predators release a smell from torn skin, which acts as an alarm signal for other salmon to evade attack. Salmon exposed to copper at levels expected during a storm event failed to respond to this alarm cue, causing higher rates of mortality in predator-prey encounters.

The scientists addressed several other natural resource management concerns, including the applicability of the new findings across salmon species and how different water conditions influence how much copper is available to injure the salmon's olfactory system.

The SeaDoc Society's Salish Sea Science Prize comes with a $2,000 cash prize. It is bestowed biennially to recognize a scientist or group of scientists whose work has resulted in the demonstrated improved health of fish and wildlife populations in the Salish Sea. It is given in recognition of, and to honor the spirit of the late Stephanie Wagner, who loved the region and its wildlife.

The SeaDoc Society is about people and science healing the sea. It funds and conducts marine science and uses science to improve management and conservation in the Salish Sea. It is a program of the Karen C. Drayer Wildlife Health Center, a center of excellence at the UC Davis School of Veterinary Medicine.