Seals, birds and humans compete for fish in the Baltic SeaNovember 13, 2017
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.
"Because fish is nutrient-rich food and angling provides valuable recreation, the 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. The debates are often based on assumptions, which is why I took the initiative to look at the problem from a scientific viewpoint," said Sture Hansson, Professor of Ecology, Environment and Plant Sciences at Stockholm University.
Together with four researchers from the Swedish University of Agricultural Sciences (SLU) and seven other colleagues from countries around the Baltic, Hansson has estimated birds' and seals' fish consumption. Seals are the primary fish-eating mammals, and their consumption is about the same as that of all birds together. Humans catch 3 to 4 times more fish than seals and birds combined.
Small-scale coastal fishing most impacted by wildlife
The fishing grounds most impacted by competition from wildlife are the coastal areas with species like perch, pike, pikeperch, brown trout, salmon, whitefish and vendace. Seals and cormorants consume similar amounts as humans. Because we know that these fish are impacted by human fishing activities, it's reasonable to conclude that they are also impacted by predation from seals and birds. Wildlife thus competes with humans for these fish resources.
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.
Based on these results, 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. This might take the shape of hunting or harassments to reduce animal abundances.
Seals and birds had no major impact on open sea fisheries for herring, sprat and cod.
Sture Hansson, Stockholm Univ., +46708-140599, email@example.com
Ulf Bergström, SLU, +4610-478 4117, firstname.lastname@example.org
Facts and figures:
Fishery catch: 700,000 tons/yr, of which 650,000 tons are herring, sprat and cod
Consumption by seals: 100,000 tons/yr, of which 60,000 tons are herring, sprat and cod. Grey seal 75,000 tons, ringed seal 20,000 tons and harbour seals 5,000 tons
Consumption by birds: 100,000 tons/yr, of which 30,000 tons are herring, sprat and cod. Cormorants consume 40,000 tons/yr, while razorbill, common guillemot, common and red-breasted merganser each consume about 10,000 tons/yr. The remaining 20,000 tons are consumed by other bird species.
Related Birds Articles:
An influenza infection in birds gives a good protection against other subtypes of the virus, like a natural vaccination, according to a new study.
Not only migratory birds use a built-in magnetic compass to navigate correctly.
Algal blooms deplete oxygen in lakes, produce toxins, and end up killing aquatic life in the lake.
Dive bombing a much larger bird isn't just a courageous act by often smaller bird species to keep predators at bay.
Forget delivering packages or taking aerial photographs -- drones can even count small birds!
New research provides insight into plumage evolution.
It turns out being the early bird really does have its advantages.
Climate change could make much of the Arctic unsuitable for millions of migratory birds that travel north to breed each year, according to a new international study published today in Global Change Biology.
The researchers' observations shed light on the effects of human population expansion on wildlife.
Unmanned Aerial Vehicles (UAVs) of the future will be able to visually coordinate their flight and navigation just like birds and flying insects do, without needing human input, radar or even GPS satellite navigation.
Related Birds Reading:
The Genius of Birds
by Jennifer Ackerman (Author)
An award-winning science writer tours the globe to reveal what makes birds capable of such extraordinary feats of mental prowess
Birds are astonishingly intelligent creatures. According to revolutionary new research, some birds rival primates and even humans in their remarkable forms of intelligence. In The Genius of Birds, acclaimed author Jennifer Ackerman explores their newly discovered brilliance and how it came about.
As she travels around the world to the most cutting-edge frontiers of research, Ackerman not only tells the story of the recently uncovered... View Details
National Geographic Backyard Guide to the Birds of North America (National Geographic Backyard Guides)
by Jonathan Alderfer (Author), Paul Hess (Author)
Essential for the millions of Americans who watch and feed birds in their backyards—whether experienced birders or new birding enthusiasts—from the experts at National Geographic and co-author of the popular and perennial best seller Field Guide to the Birds of North America.
No matter where you live—in the country, city, a high-rise or house—this handy guide will quench your curiosity about the feathered creatures in your midst. It features 150 of the most common and interesting birds likely to be observed at backyard feeders, nesting nearby or just migrating... View Details
National Geographic Field Guide to the Birds of North America, 7th Edition
by Jon L. Dunn (Author), Jonathan Alderfer (Author)
This fully revised edition of the best-selling North American bird field guide is the most up-to-date guide on the market. Perfect for beginning to advanced birders, it is the only book organized to match the latest American Ornithological Society taxonomy.
With more than 2.75 million copies in print, this perennial bestseller is the most frequently updated of all North American bird field guides. Filled with hand-painted illustrations from top nature artists (including the ever-popular hummingbird), this latest edition is poised to become an instant must-have for every serious... View Details
by Leila Jeffreys (Author)
Fine art photographer Leila Jeffreys captures the beauty and diversity of some of our most colorful and elegant feathered friends. From the exotic birds of her native Australia to those of North America, Jeffreys seems to delve into the very souls of these creatures with her stunning and evocative portraits. Jeffreys works with animal rescue and conservation groups to find subjects to photograph. Her love and compassion for her subjects is evident throughout, as she captures their personalities in her delightful portraits; Commander Skyring the Gang-Gang Cockatoo, Dexter the White-Bellied Sea... View Details
Extreme Birds: The World's Most Extraordinary and Bizarre Birds
by Dominic Couzens (Author)
Extreme Birds is a photographic showcase of 150 birds at the extremes of nature. It reveals nature's ingenuity and sometimes its sense of humor. The species in this book were chosen for their extraordinary characteristics and for behaviors far beyond the typical. They are the biggest, the fastest, the meanest, the smartest. They build the most intricate nests, they have the most peculiar mating rituals, they dive the deepest and they fly the highest. These are the overachievers of the avian world.
Some examples:Most skilled nest builder: The tiny... View Details
Birds: A Fully Illustrated, Authoritative and Easy-to-Use Guide (A Golden Guide from St. Martin's Press)
by Herbert S. Zim (Author), Ira N. Gabrielson (Author), Chandler S. Robbins (Editor), James Gordon Irving (Editor)
This guide will help you identify-quickly and easily-the birds you are most likely to see. It tells you:
What to look for
Where and when to look
How to attract birds
Range maps show where each bird is found, and handy tables at the back of the book contain a wealth of additional information about migration, eggs, nests, and food. This is the perfect bird book for beginners at any age.View Details
Birds of Texas Field Guide (Bird Identification Guides)
by Stan Tekiela (Author)
Make bird watching in Texas even more enjoyable! With Stan Tekiela’s famous field guide, bird identification is simple and informative. There’s no need to look through dozens of photos of birds that don’t live in Texas. This book features 170 species of Texas birds, organized by color for ease of use. Do you see a yellow bird and don’t know what it is? Go to the yellow section to find out. Fact-filled information, a compare feature, range maps, and detailed photographs help to ensure that you positively identify the birds that you see. View Details
Birds, Nests & Eggs (Take Along Guides)
by Mel Boring (Author)
A fun, informative take-along guide that will help children identify 15 birds. Kid will also learn how and where birds build their homes and all about their young. Plus the guide features activities that are fun and easy to do. There's also a seven-page scrapbook for drawings and notes.Invites young naturalists to spot wildlife. Safety tips are provided and interesting activities are sugested. Color illustrations enhance the presentation. ―-HORN BOOKS (Tracks, Scats and Signs) View Details
The Thing with Feathers: The Surprising Lives of Birds and What They Reveal About Being Human
by Noah Strycker (Author)
An entertaining and profound look at the lives of birds, illuminating their surprising world—and deep connection with humanity.
Birds are highly intelligent animals, yet their intelligence is dramatically different from our own and has been little understood. As we learn more about the secrets of bird life, we are unlocking fascinating insights into memory, relationships, game theory, and the nature of intelligence itself.
The Thing with Feathers explores the astonishing homing abilities of pigeons, the good deeds of fairy-wrens, the influential flocking... View Details
Birds Board Book
by Kevin Henkes (Author), Laura Dronzek (Illustrator)
In what the New York Times Book Review calls “a perfect book,” a little girl watches birds from her window and dreams she can fly. A board book edition of the critically acclaimed picture book from the award-winning husband-and-wife team of Kevin Henkes and Laura Dronzek. An ALA Notable Book.Birds “will resonate with the youngest children,” said School Library Journal. With a fine eye for detail, a girl observes and describes birds—their sizes, their colors, their shapes, the way they move and appear and disappear, and how they are most like her.... View Details