Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Tag Archive: fish

  1. Reversing America’s Wildlife Crisis—Securing a Future for our Fish and Wildlife

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    April 2 2018

    We are pleased to share with you a new report, Reversing America’s Wildlife Crisis—Securing a Future for our Fish and Wildlife – a collaboration among the National Wildlife Federation, American Fisheries Society, and The Wildlife Society.  It celebrates the extraordinary diversity of U.S. wildlife, our historic conservation successes, and calls attention to the work we have yet to do to address severe declines still affecting many of the nation’s species.


    America harbors a remarkable array of wildlife populations, enjoyed and valued by a diversity of the American public—yet many populations are in serious trouble and up to one-third of U.S. species are at increased risk of extinction. Our collective work to conserve species is continually challenged with habitat loss and degradation, invasive species, disease, and pollution all pose threats to our wildlife populations—threats that are being amplified by a rapidly changing climate.


    Our community has demonstrated that investing in conservation can make a difference. This report highlights the conservation successes made possible by your hard work implementing State Wildlife Action Plans and calls for a dramatic increase in wildlife funding—particularly through the Recovering America’s Wildlife Act—to further enable our community’s work to reverse this crisis and secure the future of our fish and wildlife heritage.


    Our hope is this report will elevate the wildlife crisis, help build support for increased funding for our nation’s wildlife, and ultimately lead to helping you do the great work you do every day. We ask you to share this report within your organization and among your colleagues, and join us in calling on Congress to support the Recovering America’s Wildlife Act.

  2. Seals, birds and humans compete for fish in the Baltic Sea

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    • Increased populations of seals and fish-eating birds in the Baltic have resulted in a sometimes contentious debate over the effects of these animals on the fish stocks.
    • [Some parallels to Point Blue studies off Farallones] Impacts of seals and birds (primarily cormorants) on fish stocks should be considered in future management plans.
    • Both reductions in fishing quotas and wildlife predation rates should be considered when fish stocks decrease so precipitously.

    Posted: 13 Nov 2017 07:47 AM PST  read full ScienceDaily article here

    In Sweden and in other parts of Europe there are concerns that seals and birds compete with humans for fish resources. For the Baltic Sea, an international study now shows that this competition is a reality.

    For some unknown reason, there has been such a dramatic reduction in eel that they are now considered critically endangered. Eel fishing has been drastically reduced and complete bans are being discussed. In this case as well, it is worth noting that the eel consumption by cormorants is at the same level as human fishing.

    …the scientists conclude that the impacts of seals and birds (primarily cormorants) on fish stocks should be considered in future management plans. Both reductions in fishing quotas and wildlife predation rates should be considered when fish stocks decrease so precipitously.

    Sture Hansson et al. Competition for the fish – fish extraction from the Baltic Sea by humans, aquatic mammals, and birds. ICES Journal of Marine Science, 2017 DOI: 10.1093/icesjms/fsx207the increased populations of seals and fish-eating birds in the Baltic have resulted in a sometimes contentious debate over the effects of these animals on the fish stocks.

  3. Plastic fibres found in tap water around the world, study reveals

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    • Tests show billions of people globally are drinking water contaminated by plastic particles, with 83% of samples found to be polluted
    • Almost 300m tonnes of plastic is produced each year and, with just 20% recycled or incinerated, much of it ends up littering the air, land and sea. A report in July found 8.3bn tonnes of plastic has been produced since the 1950s, with the researchers warning that plastic waste has become ubiquitous in the environment.

    by   Sept 5 2017 Guardian UK read full article here

    Microplastic contamination has been found in tap water in countries around the world, leading to calls from scientists for urgent research on the implications for health.

    Scores of tap water samples from more than a dozen nations were analysed by scientists for an investigation by Orb Media, who shared the findings with the Guardian. Overall, 83% of the samples were contaminated with plastic fibres.

    The US had the highest contamination rate, at 94%, with plastic fibres found in tap water sampled at sites including Congress buildings, the US Environmental Protection Agency’s headquarters, and Trump Tower in New York. Lebanon and India had the next highest rates….

    ….The new analyses indicate the ubiquitous extent of microplastic contamination in the global environment. Previous work has been largely focused on plastic pollution in the oceans, which suggests people are eating microplastics via contaminated seafood….

    A magnified image of clothing microfibres from washing machine effluent.
    A magnified image of clothing microfibres from washing machine effluent. One study found that a fleece jacket can shed as many as 250,000 fibres per wash. Photograph: Courtesy of Rozalia Project

    Microplastics are also known to contain and absorb toxic chemicals and research on wild animals shows they are released in the body…His research has shown microplastics are found in a third of fish caught in the UK…

    …The scale of global microplastic contamination is only starting to become clear, with studies in Germany finding fibres and fragments in all of the 24 beer brands they tested, as well as in honey and sugar. In Paris in 2015, researchers discovered microplastic falling from the air, which they estimated deposits three to 10 tonnes of fibres on the city each year, and that it was also present in the air in people’s homes….



  4. Warmer waters from climate change will leave fish shrinking, gasping for air

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    • Fish are expected to shrink in size by 20 to 30 per cent if ocean temperatures continue to climb due to climate change

    August 21, 2017 University of British Columbia read full ScienceDaily article here

    …A new study by researchers at the University of British Columbia provides a deeper explanation of why fish are expected to decline in size. “Fish, as cold-blooded animals, cannot regulate their own body temperatures. When their waters get warmer, their metabolism accelerates and they need more oxygen to sustain their body functions….There is a point where the gills cannot supply enough oxygen for a larger body, so the fish just stops growing larger.”…

    ….as fish like cod increases its weight by 100 per cent, its gills only grow by 80 per cent or less. When understood in the context of climate change, this biological rule reinforces the prediction that fish will shrink and will be even smaller than thought in previous studies.

    Warmer waters increase fish’s need for oxygen but climate change will result in less oxygen in the oceans. This means that gills have less oxygen to supply to a body that already grows faster than them. The researchers say this forces fish to stop growing at a smaller size to be able to fulfill their needs with the little oxygen available to them.

    Some species may be more affected by this combination of factors. Tuna, which are fast moving and require more energy and oxygen, may shrink even more when temperatures increase. Smaller fish will have an impact on fisheries production as well as the interaction between organisms in the ecosystems.

    Daniel Pauly, William W. L. Cheung. Sound physiological knowledge and principles in modeling shrinking of fishes under climate change. Global Change Biology, 2017; DOI: 10.1111/gcb.13831

  5. Marine noise pollution stresses and confuses fish

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    • European sea bass experienced higher stress levels when exposed to the types of piling and drilling sounds made during the construction of offshore structures.

    August 10, 2017 read full ScienceDaily article here

    The fish also showed signs of being confused when they encountered a potential predator while exposed to these underwater noises. When researchers played recordings of piling sounds and mimicked an approaching predator, the seabass made more turns and failed to move away from the predator.

    When exposed to drilling sounds the sea bass actively avoided these areas, spending more time in what the research team called the ‘safe zone’. The fish also took longer to recover from exposure to the underwater sounds.

    Over the last few decades, the sea has become a very noisy place. The effects we saw were subtle changes, which may well have the potential to disrupt the seabass’s ability to remain ‘in tune’ with its environment....

    Ilaria Spiga, Nicholas Aldred, Gary S. Caldwell. Anthropogenic noise compromises the anti-predator behaviour of the European seabass, Dicentrarchus labrax (L.). Marine Pollution Bulletin, 2017; 122 (1-2): 297 DOI: 10.1016/j.marpolbul.2017.06.067

  6. Small ‘weedy’ fish species to take over future oceans; acidic waters will reduce fish diversity, mid-sized predators associated with kelp

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    July 6, 2017 University of Adelaide  see full ScienceDaily article here

    The ocean acidification expected in the future will reduce fish diversity significantly, with small ‘weedy’ species dominating marine environments, researchers have demonstrated for the first time…..researchers studied species interactions in natural marine environments at underwater volcanic vents, where concentrations of CO2 match those predicted for oceans at the end of the century. They were compared with adjacent marine environments with current CO2 levels….
    ….”Small weedy species would normally be kept under control by their predators — and by predators we mean the medium-sized predators that are associated with kelp. But ocean acidification is also transforming ecosystems from kelp to low grassy turf, so we are losing the habitat that protects these intermediate predators, and therefore losing these species
    One way this biodiversity loss could be delayed is by reducing overfishing of intermediate predators.We showed how diminishing predator numbers has a cascading effect on local species diversity,” Professor Nagelkerken says. “Strong controls on overfishing could be a key action to stall diversity loss and ecosystem change in a high CO2 world.”A video about the research can be seen at Nagelkerken, Silvan U. Goldenberg, Camilo M. Ferreira, Bayden D. Russell, Sean D. Connell. Species Interactions Drive Fish Biodiversity Loss in a High-CO 2 World. Current Biology, 2017; DOI: 10.1016/j.cub.2017.06.023
  7. New Report Shows 74% of CA’s Native Salmon, Steelhead and Trout Likely to Be Extinct in 100 Years, 45% in 50 Years if Trends Continue

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    “State of the Salmonids II: Fish in Hot Water” report details crisis, IDs opportunities to reverse trend

    UC Davis Center for Watershed Science &Cal Trout, reprinted from Maven’s Notebook  May 16 2017

    Fish and watershed advocacy group California Trout (CalTrout) and University of California Davis, Center for Watershed Sciences, provided key results from an in-depth report today detailing the status of 32 types of salmon, steelhead, and trout that are native to California. State of the Salmonids II: Fish in Hot Water offers concerning data about the declining health of these fish populations and opportunities for stabilizing and even recovering many species.

    The report includes an analysis of key threats to the survival of each species, starting with the overarching threat of climate change, which is likely to reduce the availability of cold water habitat that salmon, steelhead, and trout all depend on for survival. It also highlights various other human-induced threats, such as dams, agriculture, estuary alteration, urbanization, and transportation.

    To read the report’s main findings and explore related online resources, go to  and blog post from UC Davis here.




  8. Climate change: global reshuffle of wildlife will have huge impacts on humanity

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    Mass migration of species to cooler climes has profound implications for society, pushing disease-carrying insects, crop pests and crucial pollinators into new areas, says international team of scientists

    , environment editor  The Guardian UK  Thursday 30 March 2017 Full article here

    Global warming is reshuffling the ranges of animals and plants around the world with profound consequences for humanity, according to a major new analysis. Rising temperatures on land and sea are increasingly forcing species to migrate to cooler climes, pushing disease-carrying insects into new areas, moving the pests that attack crops and shifting the pollinators that fertilise many of them, an international team of scientists has said.

    They warn that some movements will damage important industries, such as forestry and tourism, and that tensions are emerging between nations over shifting natural resources, such as fish stocks. The mass migration of species now underway around the planet can also amplify climate change as, for example, darker vegetation grows to replace sun-reflecting snow fields in the Arctic.

    Human survival, for urban and rural communities, depends on other life on Earth,” the experts write in their analysis published in the journal Science. “Climate change is impelling a universal redistribution of life on Earth.”…

  9. Biodiversity protects fish from climate change

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    Posted: 16 May 2016 03:12 PM PDT

    Fish provide protein to billions of people and are an especially critical food source in the developing world. Today marine biologists confirmed a key factor that could help them thrive through the coming decades: biodiversity. Communities with more fish species are more productive and more resilient to rising temperatures and temperature swings, according to a new study–but biodiversity made fish communities more resilient against changing climate….

    Emmett Duffy, Jonathan S. Lefcheck, Rick D. Stuart-Smith, Sergio A. Navarrete, and Graham J. Edgar. Biodiversity enhances reef fish biomass and resistance to climate change. PNAS, May 2016 DOI: 10.1073/pnas.1524465113

  10. Climate Change and Nutrition—Polar Bears, Fish

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    Land-based food not nutritionally sufficient for wild polar bears, according to new study

    Posted: 13 Sep 2016 12:05 PM PDT

    On average, a polar bear loses up to 30 percent of its total body mass while fasting during the open-water season. Although some scientists previously believed land-based foods could supplement the bears’ nutritional needs until the sea ice returns, a new study has revealed that access to terrestrial food is not sufficient to reduce the rate of body mass loss for fasting polar bears.

    Study links altered brain chemistry, behavioral impairments in fish exposed to elevated carbon dioxide

    Posted: 13 Sep 2016 09:52 AM PDT

    Increased carbon dioxide concentrations alters brain chemistry that may lead to neurological impairment in some fish, a first-of-its-kind study demonstrates.