Climate Change and Fishing; What to Expect | Kayak Angler Magazine | Rapid Media
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How is climate change affecting where you fish? Lorenzo del Bianco

For many, climate change feels like a vague concept and a distant concern – something folks will need to deal with a long time in the future.  But increasingly, the “future” has arrived.  Anglers are in a good position to notice and care about climate change, as many have already seen effects on their fishing opportunities.  Doing what we love best, we see firsthand the impact of climate change on natural systems and our wildlife.  

Climate change is already having significant impacts on fish and their habitats. Many impacts of climate change have made the transition from scientific prediction to current reality.  Folks who spend a lot of time on the water over a period of many years have noticed changes in the species mix, timing of annual migrations, and locations certain fish now frequent.  Some of these changes may be good for fishing certain species in some locations in the short term, some may be bad. 

 

With only a moderate increase in water temperature, changes in distribution, growth rates and birth rates will benefit some species.  For some other species, large population declines and possible local extinctions may occur.  More frequent and intense storms may benefit coastal spawning species, such as Atlantic croaker, that depend on winds to transport offspring into estuaries and coastal areas, while other species that require a more stable nursery environment may be adversely affected.

Scientific studies looking at the direct and indirect impacts of climate change on fisheries have developed quickly over the last 10 to 20 years, but there are still many gaps in our knowledge and unanswered questions.  Forecasts of climate change impacts on ecosystems are challenging and there are many uncertainties, partly because of our limited understanding of ecosystems even in the absence of climate change.  Climate change has different impacts in different places.  Sea level rise is expected to be more extreme in some locations and less in others. The same is true for changes in water temperature, so we can’t make blanket statements about impacts on all fisheries.  However, even with all of those caveats, there are things that we know without a doubt that will impact salt water fisheries. 

 

Global surface temperatures continue to rise.  In most surface temperature data sets, the years 2014, 2015 and again 2016 set new global heat records since the start of regular measurements. Never before have three record years occurred in a row.[1] Earth’s climate and temperatures have always fluctuated to some degree, and natural systems and organisms have developed a capacity to adapt, which will help them to cope with the impact of future changes. However, the rate of future climate change is predicted to be more rapid than previous natural changes. Fish also faces numerous additional pressures, including fishing, loss of biodiversity (including genetic diversity), habitat destruction, pollution, introduced and invasive species and pathogens (microorganisms that cause disease).[2]

 

Changing ranges and distributions of fish.

The center of summer flounder population, which was as far south as Virginia around 1970, is now off the New Jersey coast.  Changes in local temperatures are a major factor in recent geographical shifts of more than 300 different fish species: They've migrated toward the north or south poles, and even east or west into deeper waters, depending on their original locations.

Marine fish may be able to move to different habitat more rapidly than freshwater fish or land animals because they face fewer barriers.  When interviewed by Marianne Lavelle of Daily Climate about the shifting flounder population, Richard Robins chairman of the Mid-Atlantic Fishery Management Council said, "Fish have very strong thermal preferences, and they also have tails. They don't wait to be convinced."

“As temperatures have warmed in the waters off our coasts, animals with a low tolerance for that warming have just picked up and shifted,” says Malin Pinsky, a Rutgers University ecologist who is studying the changing distribution of summer flounder and other species. “I hesitate to say ‘moved,’ mainly because we don’t yet know whether fish are actually swimming, or whether they’re simply reproducing more slowly in their old ranges and faster in their new ranges.” Pinsky says lobsters that were once abundant off Long Island have moved to cooler waters of Maine while summer flounder and black sea bass, once common to the waters off Cape Hatteras, have moved north and are now more abundant off the coast of New Jersey.  Shifts in numerous species have already been documented, and many more are likely to change their distribution in response to climate change.

While a number of species are already shifting their habitat range, not all are moving at the same rate.  Although it isn’t clear how these shifts in population will affect the food web in the future, it may affect predatory species that rely on fish which have moved to survive, to find new food and prey elsewhere.

 

Loss of Wetlands.

Some of our favorite gamefish start life in areas of marshland and submerged aquatic vegetation.  Climate change will damage coastal wetlands all over the world.  Sea-level rise will destroy thousands of acres of coastal salt marshes and sea grass beds that are home to egg, larval, and juvenile stages of game fish.

Wetlands protect the shore from flooding, and they also provide important habitats for many types of plants and animals. For example, the Everglades are wetlands close to sea level in southern Florida that are home to diverse ecosystems. As sea level rises, salt water could flood parts of the Everglades, destroying wetland and changing the ecosystem.

 

Ocean acidification.

Carbon dioxide is added to the atmosphere whenever people burn fossil fuels. The ocean currently absorbs about a quarter of human-caused carbon dioxide emissions.  In the ocean, carbon dioxide reacts with seawater to form carbonic acid, leading to ocean acidification that will alter marine ecosystems in dramatic yet uncertain ways.  In the past 200 years one, ocean water has become 30 percent more acidic—faster than any known change in ocean chemistry in the last 50 million years.

The ability to adapt to higher acidity varies from fish species to fish species.  The degree to which ocean acidification will help or hurt a given fish species is largely unknown.  A shift in dominant fish species could have major impacts on the food web and on human fisheries.

Increasing acidity makes it harder for corals to build skeletons and for shellfish to build the shells they need for protection. Warmer water has already caused coral bleaching (a type of damage to corals) in many parts of the world.  By 2050, live corals could become rare in tropical and sub-tropical reefs due to the combined effects of warmer water and increased ocean acidity.  The loss of coral reefs will reduce habitat for fish and many other sea creatures and will disrupt the food web.

Different species, Different impacts

NOAA scientists recently released the first multispecies assessment of how vulnerable U.S. marine fish and invertebrate species are to a warming ocean. The study examined 82 species that occur off the Northeastern U.S., where ocean warming is occurring more rapidly than most other areas. There is a mix of good news and bad news regarding specific species that kayak anglers would be most interested in. Researchers found that most species evaluated will be affected, and that some are likely to be more resilient to changing ocean conditions than others.

 

The study generally categorizes species that are “generalists” as less vulnerable to climate change than are those that are “specialists.”  For example, croaker, Atlantic cod and yellowtail flounder are more generalists, since they can use a variety of prey and habitat, and are ranked as only moderately vulnerable to climate change.  The Atlantic sea scallop is more of a specialist, with limited mobility and high sensitivity to ocean acidification that will be more pronounced as water temperatures warm.  Sea scallops have a high vulnerability ranking.  You probably don’t fish for scallops, but you might fish for a species that dines on them.  The demise of scallops and other vulnerable non-game species will ripple up the food chain to impact the fish you target.

 

Fish and other organisms that migrate between fresh and salt water (such as sturgeon, salmon, and striped bass), and those that live on the ocean bottom (lobsters, scallops, etc.) are generally the most vulnerable to climate effects in the region.  Species that live closer to the water’s surface (such as herring and mackerel) tend to be the least vulnerable.

Approximately half the species assessed were estimated to have a high or very high vulnerability to climate change in the region including: red drum, spotted seatrout, striped bass, sea scallops, lobster, and winter flounder.  Some species may respond positively to projected climate-related changes, such as Atlantic croaker, spot, and black sea bass, among others. 

Spread of microorganisms that cause disease (pathogens)

Rising sea surface temperatures have been linked with increasing levels and ranges of diseases in humans and marine life, including corals, abalones, oysters, fishes, and marine mammals. Microorganisms have caused mass fish kills of many species, but lack of good epidemiological data on pathogens generally makes it difficult to link these to climate change.  An exception is the northward spread of two protozoan parasites (Perkinsus marinus and Haplosporidium nelsoni) from the Gulf of Mexico to Delaware Bay and further north, where they have caused mass mortalities of Eastern oysters.  Consistently low winter temperatures limit the spread of some pathogens.  The spread these and other pathogens can be expected to continue as winter temperatures become milder.

 

The long-term impact of climate change on salt water fisheries may be very large, but is also very uncertain.  What can be said with a high degree of confidence is that future fisheries will depend on progress reducing overfishing and other human-driven stresses on fish populations such as water pollution, extreme flooding caused by rapid high-volume runoff from impervious surfaces and agricultural areas, invasive species, and habitat fragmentations.  If we are able to succeed in those efforts, the accumulating effects of climate change will at least be impacting more resilient ecosystems.  If major fisheries continue to be overexploited and polluted, the additional stress of climate change will have a greater impact, because it will be acting on stressed ecosystems with fish populations that are less resilient.

 

 

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