With climate change, the oceans are becoming more acid and that is a threat to the dungeness crab, according to a study by the US National Oceanic and Atmospheric Administration.
The study says ocean acidification expected to accompany climate change may slow development and reduce survival of the larval stages of Dungeness crab.
The dungeness crab is a key component of the Northwest marine ecosystem and vital to fishery revenue from Oregon to Alaska.
The research by NOAA Fisheries’ Northwest Fisheries Science Center in Seattle indicates that the declining pH anticipated in Puget Sound could jeopardize populations of Dungeness crab and put the fishery at risk. The study was recently published in the journal Marine Biology.
Ocean acidification occurs as the ocean absorbs carbon dioxide from the combustion of fossil fuels. Average ocean surface pH is expected to drop to about 7.8 off the West Coast by 2050, and could drop further during coastal upwelling periods.
Dungeness crab is the highest revenue fishery in Washington and Oregon, and the second most valuable in California, although the fishery was recently closed in some areas because of a harmful algal bloom. The Dungeness crab harvest in 2014 was worth more than $80 million in Washington, $48 million in Oregon and nearly $67 million in California
“I have great faith in the resiliency of nature, but I am concerned,” said Jason Miller, lead author of the research, which was part of his dissertation. “Crab larvae in our research were three times more likely to die when exposed to a pH that can already be found in Puget Sound, our own back yard, today.”
Scientists collected eggs from Dungeness crabs in Puget Sound and placed them in tanks at the NWFSC’s Montlake Research Laboratory. The tanks held seawater with a range of pH levels reflecting current conditions as well as the lower pH occasionally encountered in Puget Sound when deep water wells up near the surface. Larvae also went into tanks with the even lower-pH conditions expected with ocean acidification.
“The question was whether the lower pH we can expect to see in Puget Sound interferes with development of the next generation of Dungeness crab,” said Paul McElhany, a NOAA Fisheries research scientist and senior author of the paper. “Clearly the answer is yes. Now the question is, how does that play out in terms of affecting their life cycle and populations overall?”
Larvae hatched at the same rate regardless of pH, but those at lower pH took longer to hatch and progressed through their larval stages more slowly. Scientists suggested that the lower pH may reduce the metabolic rate of embryos. That could extend their vulnerable larval period, or could jeopardize the timing of their development in relation to key food sources, researchers suggested.
Larval survival also dropped by more than half at lower pH. At pH 8.0, roughly equivalent to seawater today, 58 percent of the crab larvae – called zoeae – survived for 45 days. At pH 7.5, which sometimes occurs in Puget Sound now, survival was 14 percent. At pH 7.1, which is expected to roughly approximate the pH of water upwelling on the West Coast with ocean acidification, zoeae survival remained low at 21 percent.
“Areas of greatest vulnerability will likely be where deep waters, naturally low in pH, meet acidified surface waters,” such as areas of coastal upwelling along the West Coast and in estuary environments such Hood Canal, the new study predicts.
The study shows that embryonic salmon and herring exposed to very low levels of crude oil can develop hidden heart defects that compromise their later survival.
That means that the Exxon Valdez spill on March 24, 1989 may have had much greater impacts on spawning fish than previously recognized, according to the study published in Nature’s online journal Scientific ReportsVery low embyronic crude oil exposures cause lasting defects in salmon and herring.
“These juvenile fish on the outside look completely normal, but their hearts are not functioning properly and that translates directly into reduced swimming ability and reduced survival,” said John Incardona, a research toxicologist at NOAA Fisheries’ Northwest Fisheries Science Center (NWFSC) in Seattle. “In terms of impacts to shore-spawning fish, the oil spill likely had a much bigger footprint than anyone realized.”
Previous research has shown that crude oil disrupts the contraction of the fish heart muscle cells. Embryonic fish exposed to trace levels of crude oil grow into juveniles with abnormal hearts and reduced cardiorespiratory function.
“With this very early impact on the heart, you end up with an animal that just can’t pump blood through its body as well, which means it can’t swim as well to capture food, form schools, or migrate,” said Mark Carls, toxicologist at the Alaska Fisheries Science Center. “Crude oil is changing basic physiology, or what makes a fish a fish.”
The research builds on earlier work by the Auke Bay Laboratories, part of NOAA Fisheries’ Alaska Fisheries Science Center, which found much reduced survival of pink salmon exposed as embryos to polycyclic aromatic hydrocarbons (PAH) from crude oil.
“Our findings are changing the picture in terms of assessing the risk and the potential impacts of oil spills,” said Nat Scholz, leader of the NWFSC’s ecotoxicology program and a coauthor of the new study. “We now know the developing fish heart is exquisitely sensitive to crude oil toxicity, and that subtle changes in heart formation can have delayed but important consequences for first-year survival, which in turn determines the long-term abundance of wild fish populations.”
The Exxon Valdez spill was the largest in U.S. history, with extensive oiling of shoreline spawning habitats for Pacific herring and pink salmon, the two most important commercial fish species in Prince William Sound.
Herring larvae sampled in proximity to oil were visibly abnormal, and mortality rates were higher for pink salmon embryos at oil spill sites than unaffected regions.
The herring fishery collapsed three to four years after the spill, when the herring spawned in oiled areas reached reproductive maturity.
The paper notes that the contribution of the spill to the herring population collapse, if any, was never determined and remains controversial.
Other studies, however, tend to confirm the findings, including heart problems for fish exposed to the Gulf of Mexico Deepwater Horizon spill and even fish exposed to naturally occurring oil seeps.
The new findings suggest that the delayed effects of the spill may have been important contributors to the declines.
Scientists from the Northwest Fisheries Science Center and Alaska Fisheries Science Center temporarily exposed embryonic salmon and herring to low levels of crude oil from the North Slope of Alaska and found that both absorbed chemicals at similar concentrations in their tissues. The embryos were then transferred to clean seawater and raised as juvenile fish for seven to eight months.
Few of the exposed embryos were outwardly abnormal in any way. However, closer examination of the fish revealed subtle defects that could reduce their long-term survival.
Juvenile salmon exposed to oil grew more slowly, with those exposed to the highest concentrations growing the slowest. For salmon, early survival in the ocean is strongly influenced by juvenile growth, with smaller fish suffering higher loss to predators.
Scientists used swimming speed as a measure of cardiorespiratory performance and found that fish exposed to the highest concentrations of oil swam the slowest. Slower swimming is an indication of reduced aerobic capacity and cardiac output, and likely makes fish easier targets for predators.
Exposure to oil as embryos altered the structural development of the hearts of juvenile fish, potentially reducing their fitness and swimming ability. Poor swimming and cardiac fitness is also a factor in disease resistance.
Earlier studies on the ecosystem-scale crash of the Prince William Sound herring population several years after the Exxon Valdez spill were based on higher levels of exposure to the oil. The new study shows that that cardiac injury occurs in normal-appearing fish that survive even lower level exposures.
The scientists reviewed data on measured oil concentrations in surface water samples collected in Prince William Sound after the oil spill and during the 1989 herring spawning season. Most of the 233 samples contained less oil than was believed to be toxic to herring at the time, based on visible gross developmental abnormalities. However, nearly all of the samples contained oil at or above concentrations shown in the new study to alter heart development.
If the Exxon Valdez spill impacted heart development among a large majority of fish that were spawned in proximity to oiled shorelines, the subsequent losses of juveniles to delayed mortality would have left fewer adults to join the population. Although not direct proof, this provides a plausible explanation for the collapse of the Prince William Sound herring stock four years later, when fish spawned during the oil spill would have matured.
The study concludes that the impacts of the Exxon Valdez spill on near shore spawning populations of fish are likely to have been considerably underestimated in terms of both the geographic extent of affected habitat and the lingering toxicity of low levels of oil. The findings will likely contribute to more accurate assessments of the impacts of future oil spills, Incardona said. “Now we have a much better idea of what we should be looking for,” he said.
That means, according to the study “that the impacts of the Exxon Valdez oil spill on populations of near shore spawning fish are likely to have been considerably underestimated, in term of both the geographic extent of affected habitats and the lingering toxicity of low levels of residual oil.”
The report calls for more studies of the sensitivity of the developing fish heart since the vulnerability “also has implications for other pollution sources in marine ecosystems, including increasing maritime vessel traffic and expanding land-based urban runoff.”
Scientific studies after the Exxon Valdez spill indicated that the vast majority of species recovered following the spill and that functioning ecosystems, similar to those existing pre-spill, were established.
Species for which recovery is not fully apparent, such as Pacific herring, killer whales, and pigeon guillemots, appear to have been affected by other environmental factors or human influences not associated with the oil spill. Insufficient pre-spill baseline data on these species contributed to difficulties in determining the extent of spill effects.
Based on the evidence, the Panel finds that natural recovery of the aquatic environment after an oil spill is likely to be the primary recovery mechanism, particularly for marine spills. Both freshwater and marine ecosystem recovery is further mitigated where cleanup is possible, effective, and beneficial to the environment.
Natural processes that degrade oil would begin immediately following a spill. Although residual oil could remain buried in sediments for years, the Panel finds that toxicity associated with that oil would decline over time and would not cause widespread, long-term impacts.
Oil spills kill fish. That’s well known. Now scientists say they have found out why oil spills kill adult fish. The chemicals in the oil often trigger an irregular heartbeat and cardiac arrest.
A joint study by Stanford University and the US National Atmospheric and Oceanic Administration have discovered that crude oil interferes with fish heart cells. The toxic consequence is a slowed heart rate, reduced cardiac contractility and irregular heartbeats that can lead to cardiac arrest and sudden cardiac death.
The study was published Feb. 14, 2014 in the prestigious international journal Science and unveiled at the convention of the American Association for the Advancement of Science in Chicago.
The study is part of the ongoing Natural Resource Damage Assessment of the April 2010 Deepwater Horizon oil spill in the Gulf of Mexico.
Scientists have known for some time that crude oil is known to be “cardiotoxic” to developing fish. Until now, the mechanisms underlying the harmful effects were unclear.
Studies going back to the Exxon Valdez oil spill in Alaska in 1989 have shown that exposure to crude oil-derived chemicals disrupt cardiac function and impairs development in larval fishes. The studies have described a syndrome of embryonic heart failure, bradycardia (slow heart beat), arrhythmias (irregular heartbeats) and edema in exposed fish embryos.
After the Gulf of Mexico spill, studies began on young fish in the aftermath of the Deepwater Horizon spill. The two science teams wanted to find out how oil specifically impacts heart cells.
Crude oil is a complex mixture of chemicals, some of which are known to be toxic to marine animals.
Past research focused on “polycyclic aromatic hydrocarbons” (PAHs), which can also be found in coal tar, creosote, air pollution and stormwater runoff from land. In the aftermath of an oil spill, the studies show PAHs can persist for many years in marine habitats and cause a variety of adverse environmental effects.
The scientists found that oil interferes with cardiac cell excitability, contraction and relaxation – vital processes for normal beat-to-beat contraction and pacing of the heart.
Low concentrations of crude
The study shows that very low concentrations of crude oil disrupt the specialized ion channel pores – where molecules flow in and out of the heart cells – that control heart rate and contraction in the cardiac muscle cell. This cyclical signalling pathway in cells throughout the heart is what propels blood out of the pump on every beat. The protein components of the signalling pathway are highly conserved in the hearts of most animals, including humans.
The researchers found that oil blocks the potassium channels distributed in heart cell membranes, increasing the time to restart the heart on every beat. This prolongs the normal cardiac action potential, and ultimately slows the heartbeat. The potassium ion channel impacted in the tuna is responsible for restarting the heart muscle cell contraction cycle after every beat, and is highly conserved throughout vertebrates, raising the possibility that animals as diverse as tuna, turtles and dolphins might be affected similarly by crude oil exposure. Oil also resulted in arrhythmias in some ventricular cells.
“The ability of a heart cell to beat depends on its capacity to move essential ions like potassium and calcium into and out of the cells quickly.” said Barbara Block, a professor of marine sciences at Stanford. She said, “We have discovered that crude oil interferes with this vital signalling process essential for our heart cells to function properly.”
Nat Scholz, leader of the Ecotoxicology Program at NOAA’s Northwest Fisheries Science Center in Seattle said.”We’ve known from NOAA research over the past two decades that crude oil is toxic to the developing hearts of fish embryos and larvae, but haven’t understood precisely why.”
Long term problems in fish hearts
He added: “These new findings more clearly define petroleum-derived chemical threats to fish and other species in coastal and ocean habitats, with implications that extend beyond oil spills to other sources of pollution such as land-based urban stormwater runoff.”
The new study also calls attention to a previously under appreciated risk to wildlife and humans, particularly from exposure to cardioactive PAHs that can also exist when there are high levels of air pollution.
“When we see these kinds of acute effects at the cardiac cell level,” Block said, “it is not surprising that chronic exposure to oil from spills such as the Deepwater Horizon can lead to long-term problems in fish hearts.”
The study used captive populations of bluefin and yellowfin tuna at the Tuna Research and Conservation Center, a collaborative facility operated by Stanford and the Monterey Bay Aquarium. That meant the research team was able to directly observe the effects of crude oil samples collected from the Gulf of Mexico on living fish heart cells.
“The protein ion channels we observe in the tuna heart cells are similar to what we would find in any vertebrate heart and provide evidence as to how petroleum products may be negatively impacting cardiac function in a wide variety of animals,” she said. “This raises the possibility that exposure to environmental PAHs in many animals – including humans – could lead to cardiac arrhythmias and bradycardia, or slowing of the heart.”
The Deepwater Horizon disaster released over 4 million barrels of crude oil during the peak spawning time for the Atlantic bluefin tuna in the spring of 2010. Electronic tagging and fisheries catch data indicate that Atlantic bluefin spawn in the area where the Deepwater Horizon drilling rig collapsed, raising the possibility that eggs and larvae, which float near the surface waters, were exposed to oil.
The spill occurred in the major spawning ground of the western Atlantic population of bluefin tuna in the Gulf of Mexico. The most recent stock assessment, conducted in 2012, estimated the spawning population of the bluefin tuna to be at only 36 percent of the 1970 baseline population. Additionally, many other pelagic fishes were also likely to have spawned in oiled habitats, including yellowfin tuna, blue marlin and swordfish.
Block and her team bathed isolated cardiac cells from the tuna in low dose crude oil concentrations similar to what fish in early life stages may have encountered in the surface waters where they were spawned after the April 2010 oil spill in the Gulf of Mexico.
They measured the heart cells’ response to record how ions flowed into and out of the heart cells to identify the specific proteins in the excitation-contraction pathway that were affected by crude oil chemical components.
Fabien Brette, a research associate in Block’s lab and lead author on the study said the scientists looked at the function of healthy heart cells in a laboratory dish and then used a microscope to measure how the cells responded when crude oil was introduced.
“The normal sequence and synchronous contraction of the heart requires rapid activation in a coordinated way of the heart cells,” Block said. “Like detectives, we dissected this process using laboratory physiological techniques to ask where oil was impacting this vital mechanism.”
The Seattle-based trawler Alaska Beauty recently had a great week of halibut fishing… Only one problem: Alaska Beauty wasn’t supposed to be fishing halibut; it was supposed to be fishing cod.
Despite that, 43 percent of its catch was halibut. All of that halibut, by law, must be dumped back into the sea. Most of it goes back dead. Some Alaskans are starting to get angry at this sort of large “by-catch” of halibut by Pacific Northwest and Kodiak-based trawlers at a time when the species’ stocks are declining, and Alaska charter and commercial longline fisheries are locked in a bitter battle over every flatfish.
An anonymous blogger who goes by the name of Tholepin says “228,800 pounds of halibut wasted by draggers just last week,” Tholepin notes in the latest post. “Value? In cash terms to longliners, about $1.6 million. In lost reproductive potential, in lost growth potential, in long-term resource damage; all unknowns ..
There is growing anger to the north of us in Alaska, over halibut allocation policies by the US National Ocean and Atmospheric Administration. If Kitimat is the centre of opposition by the recreational halibut sector in British Columbia, in Alaska, much of the opposition is in the town of Homer.
Business members of the Homer Chamber of Commerce voted Sunday night in favor of a letter to the National Marine Fisheries Service that asks for another look at how halibut are allocated…
Members request NMFS Catch Share Plan allocation to closely approximate the Guideline Harvest Level for Area 3A, the central Gulf of Alaska including Cook Inlet and Homer…
The Catch Share Plan proposal to reduce halibut take on chartered sport fishing boats is viewed as a measure that could damage the charter sport fishing industry in Homer as well as the town’s economy as a whole. That’s a problem for the whole town to deal with, since every bait shop, kayak rental and pottery shop is tied to it, business owners told the chamber….
“We have before us an issue that can break us,” said Jack Montgomery, owner of Rainbow Tours for the past 30 years. “This could tear our town apart.”
My quota has suffered substantial cuts over the last three years as a result of commercial legal halibut biomass decline, and the explosive unregulated growth of the halibut charter industry….Currently, based on 2011’s TAC I am legally able to harvest a little over half of what I had originally purchased, but I realize the resource is changing and the initial shares I bought were not a fixed amount. Fish stocks rise and fall just as our stock market does for a number of reasons and influences…..
Fisheries politics should not and should never be discussed by unqualified, uneducated members of a biased Chamber at the city level. The issues that are at the forefront of this discussion are not city issues; they are federal and they are international and there are two perfectly capable, if not perfect, agencies that do deal directly with the issues at the forefront of this debate – the International Pacific Halibut Commission and the National Marine Fisheries Service…. here is a reason for the Catch Sharing Plan that goes above and beyond what you and I know about the halibut stocks on an international level, not just what goes on in Cook Inlet and Kachemak Bay at the end of a fishing pole.
Editor’s note: With this entry, Northwest Coast Energy News launches its planned expansion of coverage from energy and energy related environment issues to include other environmental and related issues in the northwest, including fishery issues.
For the past year, anglers, guides and outfitters on the British Columbia coast have been concerned about the allocation problems with the halibut fishery, with the Department of Fisheries and Oceans sticking to the original quota system of 88 per cent of the total allowable catch going to the commercial fishery and 12 per cent to the recreational fishery, which includes both recreational anglers and the tourist industry.
There have been parallel problems in the state of Alaska, where the National Oceanic and Atmospheric Administration, which governs the US fishery, began moves to take away the licences from many of the halibut charter operators on the lower end of the income scale. That move is currently being challenged in a federal court in Washington, DC.
On Thursday, NOAA proposed solutions to Alaska halibut dispute, in effect, handing the hot potato decision on halibut allocationover to the International Pacifc Halibut Commission, suggesting that the Commission decide the split for charter and commercial allocation when making the overall decision on total allowable catch. NOAA has also proposed allowing Alaska halibut charter operators to buy commercial quota, similar to the Canadian proposal from the Department of Fisheries and Oceans last winter.
The International Pacific Halibut Commission, through which the United
States and Canada jointly manage the halibut resource from California to
the Bering Sea, would determine total commercial and charter catch
limits for southeast Alaska and the central Gulf of Alaska each year
before the fishing season….
Allocations to the charter and commercial sectors would vary with changes in the number of halibut available for harvest as determined by the best available science.
The International Pacific Halibut Commission would
divide the annual combined catch limits into separate annual catch limits for the commercial and guided sport fisheries. The CSP (catch sharing plan) allocates a fixed percentage of the annual combined catch limit to the guided sport and commercial fisheries. The fixed percentage allocation to each sector varies with halibut abundance. The IPHC would multiply the CSP allocation percentages for each area by the annual combined catch limit to calculate the commercial and guided sport catch limits in net pounds. At moderate to low levels of halibut abundance, the CSP could provide the guided sport sector with a smaller poundage catch limit than it would have received under the GHL (guideline harvest levels) program. Conversely, at higher levels of abundance, the CSP could provide the guided sport sector with a larger poundage catch limit than it would have received under the GHL program.
The North Pacific Fishery Management Council intended the CSP sector allocations to balance the needs of the guided sport and commercial sectors at all levels of halibut abundance.
Although the CSP allocation method is a significant change from the current allocation method under the GHL, National Marine Fisheries Service believes that the allocation under the CSP provides a more equitable management response
On the issue of buying commercial quota, the NOAA release says:
The catch sharing plan would authorize transfers of commercial halibut individual fishing quota to charter halibut permit holders for harvest by anglers in the charter halibut fishery.
Those transfers would offer charter vessel anglers in southeastern Alaska and the central Gulf of Alaska an opportunity to catch additional halibut, up to specified limits.
The news release goes on to say:
The North Pacific Fishery Management Council recommended the rule to
establish a clear allocation between the commercial and charter sectors
that fish in these areas.
Currently, the commercial and charter halibut fisheries are managed
under different programs. The commercial halibut fishery has been
managed under a catch limit program since 1995. The charter halibut
sector has been managed under a different harvest guideline since 2003,
which gives charter fishermen a number of fish they can catch per guided
angler per day, but does not ensure the overall catch stays within a
definitive catch limit.
The proposed catch sharing plan, which is scheduled to be in place by
2012, is designed to foster a sustainable fishery by preventing
overharvesting of halibut and would introduce provisions that provide
flexibility for charter and commercial fishermen.
Those who wish to comment on the draft policy must respond before September 6.