Selected tags: Climate change

Closed areas can decrease uncertainty in effects of climate change on New England Fisheries

Gulf of Maine Map

Photo Credit: New England Coastal Wildlife Alliance

As fishermen around New England will be the first to point out, this summer, much like last year, has been abnormal. The ocean waters were warmer and cod, haddock, and flounders—the mainstay of our fishing industry for centuries—are increasingly elusive. There’s plenty of blame to go around, including decades of mismanagement and overfishing, inexact science and a mismatch in abundance of certain predatory species. Looking beyond these factors, the impact of climate change on fisheries is another factor driving fish abundance that’s worth a hard look.

The level of carbon dioxide in the Earth’s atmosphere has now exceeded 400 parts per million, contributing to rising ocean temperatures. Some of the fastest increases in the last few decades have occurred in the Northwest Atlantic, and 2012 registered the largest annual increase in mean sea surface temperature for the Northwest Atlantic in the last 30 years.  

It is clear that climate change is disrupting New England’s fisheries right now; it is no longer an abstract, future scenario.

In the face of this evidence, fisheries managers need to factor in climate change alongside fishing effort and other elements when determining how to manage and rebuild fish stocks. The impacts of climate change can prevent fisheries management inactions from rebuilding fish populations, and conversely, excess fishing pressure can hinder the ability of a fish population to adapt to changes in climate. As I have written recently, a network of well-designed closed areas represents a promising management strategy to address the effect of climate change on fisheries.

Warming waters, shifting populations:

The mechanisms by which shifts in water temperature affect fish populations are not completely understood, but temperature driven changes have been observed in various species. Species’ response to climate change may be manifested as a shift in geographical distribution of the species, an expansion or contraction of the species’ range, or a change in depth distribution. Shifts in abundance are likely to be most apparent for species on the southern end of their range, and indeed shifts in fisheries distribution caused by warming waters are already taking place in the Northwest Atlantic. One study found a number of fish stocks in New England have shifted their center of biomass northward over the past 40 years.

Climate-driven shifts have been documented for cod in particular, one of the most economically, ecologically, and culturally important fish species in New England. Cod stocks on Georges Bank and in the Gulf of Maine are at the southern end of their range in the Northwest Atlantic. Temperature influences the distribution of cod in the region, and warmer water temperature has also been linked to a decline in productivity in the Gulf of Maine.

While climate change may be affecting iconic species in New England fisheries, other species may also be shifting their distribution north to areas where they are not typically found. Several news articles in local media outlets this summer featured fishermen who described the changes they’ve witnessed in the distribution of fish species. Fishermen in Maine have seen increasing numbers of black sea bass and longfin squid – species not traditionally seen in the Gulf of Maine – while fishermen in Rhode Island are catching warm water species like cobia and Atlantic croaker.

Finding management solutions to uncertain changes:

The New England Fishery Management Council is currently working to design a new network of closed areas in the region, which would build resilience in the fishery by providing protection for fish, as they shift their distribution and as they adapt to a changing ecosystem, thereby protecting fishermen’s businesses in the long-term.

Closed areas can protect the territory most critical to the productivity of target fish species, including important but vulnerable habitats, areas important for foraging and areas that harbor critical life stages like large spawners and juveniles. Refuges from fishing pressure can provide further resilience for fish species faced with a changing environment and a well-designed network of closed areas provides important stepping stones for fish species shifting their distribution in response to warming waters.

One way to increase resilience to climate change is to rebuild the population structure for overexploited fish stocks. Fishing pressure typically targets the largest (and oldest) fish. However, large, old females are typically more successful breeders, producing a much larger number of healthy larvae, and spawning more frequently than their smaller counterparts. Closed areas designed around known spawning grounds or other areas where these large females congregate can preserve a population of older, larger fish within the stock, reducing their exposure to fishing pressure and allowing them to reproduce and contribute to stock rebuilding.

Climate change needs to be considered when designing properly functioning closed areas, understanding that both fish and fishing effort may shift as a result of environmental change.

Uncertainty is inherent in both the marine ecosystem and our management of fisheries, and creating closed areas can ensure some level of insurance against this uncertainty.  A closed area network for New England’s fisheries should be broadly distributed throughout the region to provide refuges to fish, particularly as stocks shift northward from their traditional areas of abundance. A well-designed network of linked closed areas can allow species distribution to shift in response to climate change, but remain at least partially protected. This will be important not only to fish but to fishermen, creating the resiliency needed in a healthy fishery to support the long-term interests of the fishing industry.

This closed area network can provide resilience to climate change in the near term, and can be adapted to meet changing conditions as species shift.  The Council needs to consider climate change when making decisions about developing this closed area network.  They should not miss the opportunity to take a positive step in the direction of managing for a changing climate.

Dr. Sarah Smith is a member of EDF Ocean's Spatial and Ecosystems Initiatives team

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Climate Change is Changing Fisheries

Recently, the impacts of climate change on fisheries have been in the news.  The emphasis has been on the inability of scientists to explain how climate change is affecting fisheries or to fix the problems it seems to be causing.  These include shifting distribution and abundance patterns of commercially valuable fish stocks – shifts that may leave fishermen stranded with very restrictive catch limits, even when they have been doing everything possible to protect and restore their stocks.  These problems are being felt acutely in New England, where catch of some valuable stocks has been highly restricted to rebuild stocks depleted by overfishing – but they face even more restrictions as scientists find less fish in the water, possibly due to migrations induced by climate change.

A better scientific understanding of how climate change influences the distribution and abundance of fish is certainly needed, but that may be less important than the need for more flexible human institutions that can rapidly adjust to those changes.

The fact that we’ve allowed greenhouse gases to accumulate in the atmosphere means that the ocean has warmed too.  The ocean is even more resistant to remediation efforts than the atmosphere due to its enormous thermal inertia.  The ocean will hang on to that heat for decades, resulting in changing temperatures at sea.  Because fish favor certain ranges of temperatures over others, this should cause fish stocks to migrate in pursuit of their favorite temperatures. A new study shows that catch composition has been changing over the last several decades in ways that support this hypothesis: warmer water species are being caught in areas where catch used to be dominated by cold water species.  This state of affairs demands institutions that are flexible and can adjust rapidly to changing conditions.

Most fishery institutions, on the other hand, seem inflexible and incapable of rapid adjustment to a changing world. For example, the Pacific Salmon Treaty of 1985 allocated harvest of shared stocks of salmon to the United States and Canada based on average distributions.  But then, changes in the distribution and abundance of salmon (which are prone to such changes, being migratory) resulted in a fish war between these two strong allies.  In many other fisheries, too, declines in fish stocks have led to declines in  allowable catch limits, leaving  fisherman who invested in boats and gear during boom times saddled with debt.

Catch share programs, in which shares of allowable catch are allocated to individuals or groups, are much more suitable to a world in which the climate is changing. Shareholders can buy or sell shares, allowing the fishery to contract or expand depending on how many fish are around.  For example, fishing capacity had built up to high levels in the Pacific groundfish fishery, resulting in a federal buyout of about half of the capacity.  However, the fishery was still constrained by very low catch limits for species depleted by decades of overfishing.  Catch shares have allowed the fleet to adjust to these new catch limits by incentivizing fishermen to extract more value from their catch and engage in creative strategies to avoid catching the overfished species. Read More »

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Newsflash! Warming oceans=changes in fish populations and ecosystems

A number of scientific studies indicate that warming waters are affecting fish populations globally—and often in unpredictable ways. This finding is significant for fisheries management because as fish populations shift, whole ecosystems are changed. A recent study covering 40 years of data illuminates these changes in fish distributions and a Huffington Post article examines the research conducted to date and highlights the uncertain implications of this knowledge. The article extensively quotes our own scientist and Director of Spatial Initiatives, Jake Kritzer. Jake comments on the difficulty of making management predications without a complete understanding of how complex underwater ecosystems are shifting:

“It's an immensely complicated situation. You have climate change overlaying everything, and it seems to be changing the way everything works, which means we have a lot of problems. It's getting harder and harder to assess the stocks, to model them and understand their dynamics and predict what's going to happen. Because those models are based on years and years of experience reading fish stocks and studying them, they have been tested over a long time and they rely on a certain set of assumptions and conditions that now seem to be rapidly changing. Tools that have been fairly well established and worked well in the past just don't seem to be working as well anymore."

Read the full Huffington Post article: http://www.huffingtonpost.com/2013/05/17/ocean-climate-change-fishing-industry_n_3275505.html

Access the recent study published in Nature from researchers in British Columbia: http://www.nature.com/nature/journal/v497/n7449/full/497320a.html

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Building Resilient New England Fisheries in the Face of Climate Change

Photo Credit: Natacha Hardy.
Alex Koeberle and Scituate Fisherman Frank Mirarchi

By: Alex Koeberle and Jake Kritzer

Following the hottest summer ever on record, the Atlantic coast was rocked recently by super storm Sandy, both stark reminders that climate change is increasing the frequency and severity of extreme weather events.  This year had already seen effects of climate change take on a more prominent place in marine conservation debates.  In July, renowned Australian ecologist Dr. Roger Bradbury argued that the fate of coral reefs is essentially sealed due to warming waters, rising seas, acidification and extreme weather (although other prominent voices were quick to counter such doomsday predictions).  Closer to home, an effort to restore Atlantic salmon to the Connecticut River was ended after nearly a half-century, in part because changing ocean currents, temperature regimes and plankton production might be impairing the ability of salmon to survive at sea and migrate back to spawn.

It is not only salmon that are contending with effects of climate change in New England.  The region is seeing sea levels rising faster than many other places around the globe, which threatens to drown salt marshes already struggling with excessive nutrient loads.  Marshes help buffer coastal areas against storm surge, and provide vital nursery and feeding grounds for many important fish species.  Ocean waters are not only rising but warming as well, one consequence of which has been a dramatic shift in the distribution of cod north of the primary fishing grounds in the western Gulf of Maine.  Also, rainfall patterns are becoming increasingly erratic, altering salinity profiles and plankton production, which hampers productivity of species throughout the food web. Read More »

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Disaster Funds and Cod Problems: Setting the Record Straight about Fisheries in New England

Cod

Photo from NOAA

New England has received a lot of media attention recently about the fisheries disaster declared by President Barack Obama. The precipitous decline in groundfish in New England waters has created an imminent need to help fishermen and fishing communities that depend on stable healthy fish populations.

It is important to dispense with false rumors and to set the record straight.  There is an effort on the part of some to claim that catch shares are somehow responsible for the New England groundfish population declines. To claim this is to suggest that fishermen have exceeded their catch limits and are not following the rules. This is simply not true. In fact, sector fishermen have been working hard to stay under their catch limits, and in some cases remain well below these limits.

In reality, the disaster declaration was based on the fact that there are changes happening in the ecosystem that are impeding the rebuilding of fish populations.  We are forced to confront the frightening reality that fishing is changing in part because our oceans are changing.  We are dealing with a resource problem, not a management problem. Read More »

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Climate Change Threatens Chemical Composition of the Oceans

Rod FujitaThe recent U.N. Climate Change conference in Copenhagen highlighted the range of challenges associated with fighting climate change, from cutting energy use to financing clean technology in developing countries.  Why the global sense of urgency and focus?  Because the impacts of climate change are already being felt.  Most of our discussions center on the dangers of sea level rise, which is already inundating low-lying islands and valuable wetlands; on changes in precipitation and air temperature, which will affect everything from agriculture to asthma; and on the shift in seasons and habitat that will make life difficult for trees, butterflies, and the other wildlife we are familiar with.

Enormous threats indeed.  And it is perhaps inevitable that we are focused on the land and our fellow terrestrial inhabitants.  But let us not forget the fact that we are changing the ocean profoundly in many ways.  A recent study suggests that over a third of the entire ocean is heavily impacted by human activities, and that there is no longer a single patch of seawater anywhere that can be said to be pristine.  And incredibly, we are not just affecting patches of the ocean here or there – we are changing the very chemistry of the seas, chemistry that has remained stable for millennia and which defines the parameters for life in the sea and also for the habitability of the planet for us.

All living systems are buffered from extreme change by their chemistry.  If not for the carbonate/bicarbonate and other buffering chemicals in our blood, the pH (a measure of acidity) would fluctuate wildly and none of the myriad proteins or enzymes essential for life would function.  Because pH is a logarithmic scale, very small changes in pH can be disastrous for life – for example, a change of less than one pH unit is lethal to humans. Oceans along coast

The ocean is a gigantic living system, and is perhaps one of the best-buffered systems on the planet.  Enormous quantities of buffering chemicals have been entering the ocean each year for billions of years.  Remarkably, though, even the ocean is not impervious to the impacts of fossil fuel combustion and carbon dioxide emissions. 

As atmospheric carbon dioxide concentrations have risen, the ocean has steadfastly taken up about 2 billion tons of it every year, protecting us from an even more serious climate crisis than we have already.  However, carbon dioxide reacts with seawater to create carbonic acid.  As a result, while the pH of the ocean varies widely in response to local conditions, scientists have detected a noticeable drop in pH (an increase in average acidity) over the last 20 years and project a decrease in pH by 0.3-0.4 units – a huge change -  by 2100 if nothing is done to reduce carbon dioxide emissions. 

Read More »

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