Blog Tags: Gillnets
In the video above, people are shocked that a fisherman accidentally caught two great whites off of the pier at Manhattan Beach in Los Angeles in the same day (both sharks were released). But, in fact, this isn’t too surprising given that the waters off of Southern California are the main nursery grounds for our west coast population of great white sharks.
Researchers believe young great white shark “pups” spend their first couple years in the warm ocean waters off Southern California and Northern Mexico, where they feed on several species of forage fish like squid, mackerel, anchovies, sardines and hake. Researchers also believe Southern California waters may serve as birthing sites for great white pups as well. After reaching about 6 years of age, great whites get big enough to join the other adult sharks that feed on seals and sea lions, playing an important ecological role as some of the ocean’s few natural predators. Ultimately, this helps keep our ocean food web in balance, ensuring healthy marine wildlife populations and vibrant fishing opportunities.
In this thought-provoking piece on the National Geographic's Ocean Views blog, Mediterranean Science Commission director general Frederic Briand discusses the precarious and uncertain fate of ocean creatures staring down extinction. About sharks and rays he writes:
These are not target species in Mediterranean fisheries but increasingly threatened, as unreported bycatch, by highly intensive fishing and bottom trawl. The status of many of them is unclear, even for species as conspicuous as the sawfish Pristis pectinata (last seen in 1902), the mako shark Isurus oxyrinchus, or the sandtiger sharks Carcharias taurus and Odontaspis ferox, once abundant and now presumed locally extinct.
But it is the baiji, or Yangtze River dolphin, the first marine mammal to go extinct in modern times, that captures the imagination--the passenger pigeon or dodo for our day.
Nearly blind, the baiji patrolled the turbid waters of the Yangtze River for millenia but has not been seen in almost a decade. It was declared extinct earlier this year by the Chinese government. The dolphin likely succumbed to decades of development, pollution, entanglements in fishing gear, ship strikes and an increasingly chaotic acoustic environment in the Yangtze that proved lethal to a species almost entirely dependent on sound to communicate, find food and find mates.
Now the vaquita, a porpoise in the Sea of Cortez (literally "little cow") takes up the unenviable mantle of most endangered cetacean in the world. The largest threat faced by the vaquita are gillnets.
We have good news to share: the National Marine Fisheries Service (NMFS) has looked at our petition to have West Coast great white sharks listed as an endangered species – a petition 44,000 of you backed – and has agreed to take it to the next level!
Having agreed that these sharks may qualify for endangered status, NMFS will now spend the next nine months researching the sharks and will announce their final decision in June 2013.
This is an important milestone, and we want to thank you for helping make it happen. Those 44,000 signatures showed that great whites have supporters across the country and that people are paying attention to what happens off our shores. We're so grateful for your help – and the sharks are too.
Recent scientific studies show that great white sharks off the coast of California and Baja California, Mexico are genetically distinct and isolated from all other great white shark populations and that there are only a few hundred adult sharks remaining in this population.
The biggest threat to great white sharks on the West Coast right now are the gillnets that are trapping their young. We're hoping that this effort will lead to more research, increased observer coverage and management of the fisheries that are harming them, and more awareness of the importance and vulnerability of these magnificent creatures. Great white sharks are a vital part of the ocean food web, and we can’t let them disappear.
We will keep you posted as the story unfolds!
Since a lot of what happens in the oceans is hidden from view, the issues we discuss here on the blog can often be abstract and hard to visualize.
That’s why starting today, I’ll be featuring an ocean infographic by artist Don Foley each week. These infographics also appear in Oceana board member Ted Danson’s book, “Oceana: Our Endangered Oceans and What We Can Do to Save Them.”
I thought I’d start with one of the most mysterious players in the ocean: fishing gear. I don’t know about you, but I’ve never actually seen any of these in real life (have you?), so I find this infographic quite helpful:
Dredges catch scallops and fish by dragging across the seafloor. They can crush corals, catch sea turtles, and disturb all kinds of seafloor life.
Purse seine nets catch schooling fish like tuna by encircling the school with a wall of netting. They can capture dolphins and other natural predators feeding on the school.
Trawl nets catch shrimp, cod, haddock, and other fish. Bottom trawls drag weighted nets across the seafloor, crushing corals or any other marine life in their path. Bottom trawls also discard more unwanted fish than almost any other form of fishing and are extremely destructive. Midwater trawls drag large nets through the water to catch pollock and other schooling fish, and when their nets are full, they may also drag on the bottom.
Gillnets are one of the most widely used methods in the world for catching salmon and sharks. When not closely tended, gillnets can entangle and drown sea turtles, seabirds, and marine mammals. Some gillnets also snag large numbers of juvenile fish, which contributes to overfishing.
Read more about fishing weaponry and see a larger version of this infographic, and come back next week to ogle more ocean visuals!
This is the fourth in a series of posts about this year’s Ocean Hero finalists.
For more than two decades, Peter Wallerstein has been rescuing marine animals on the coast of California.
In 1985 he founded the Whale Rescue Team, which is now part of Marine Animal Rescue (MAR), a project of Friends of Animals. Peter started a 24-hour hotline for citizens to report stranded or injured marine mammals, and he has personally rescued more than 4,000 marine mammals and birds in Southern California, from stranded dolphins to whales tangled in gillnets.
Thanks to Peter’s persistence, Los Angeles County now has the only professional marine mammal rescue team in the U.S. that conducts hundreds of rescues each year, working 24/7 if needed. In April he conducted 86 marine mammal rescues, 120 for the year so far.
Now Peter is working to address the lack of adequate care facilities for marine mammals. After a decade of work, the National Marine Fisheries Service (NMFS) has authorized MAR to design, construct and operate a second marine mammal care facility in Los Angeles County.
The study found that 85,000 sea turtles were reported caught by commercial fisheries worldwide over the last 20 years, but the scientists estimate that the actual number is two orders of magnitude higher than that -- in the millions.
The 85,000 figure only accounts for sea turtle bycatch that was reported, but the actual number of turtles caught is significantly higher because typically less than 1% of fleets have fishing observed and many small scale fisheries have no observer coverage at all.
The study looked at sea turtles caught by gillnets, longlines and trawls, three of the most commonly used fishing gear types. The bottom line here is that the number of sea turtles caught as bycatch is enormous. Without additional bycatch reduction and better enforcement of established protections, many sea turtle populations may go extinct.