Tag Archives: squids

LED-equipped fishing nets help protect wildlife from unintentional captures

Green light-emitting diode (LED) lights can help protect wildlife from fishing nets, new research reports.

Image credits Paul Lee.

Affixing green LED lights to fishing nets can significantly reduce the catch of nontargeted animals such as sharks, squids, or turtles, according to a team led by researchers from the Arizona State University. The addition of these lights doesn’t impact the quantity or quality of desired catch species (i.e. commercially-available fish), which helps raise confidence that fisheries will adopt the measure. That being said, the installation of these lights comes with a significant upfront cost per net, which many fisheries may not be able to afford.

Beyond practical concerns, however, the findings showcase that it is possible to maintain our current fishing efficiency while insulating species that aren’t desired from capture.

Lights in the deep

Coastal fisheries routinely use gillnets, devices that resemble chain-link fences, to capture fish. These nets are deployed for up to several days at a time and capture virtually every kind of marine wildlife that cannot fit through their holes. Undesired captures (“bycatch”) are tossed overboard once the nets are recovered. These animals experience very high rates of death following this, adding up to significant pressure on marine species such as dolphins and sea turtles. It also impacts the fisheries’ bottom line, as personnel waste time removing these animals from the nets.

In other words, both business and nature lose out from the use of gillnets.

John Wang, a marine ecologist at the National Oceanic and Atmospheric Administration (NOAA), and his colleagues previously designed illuminated nets in order to protect turtles from becoming bycatch, back in 2016. Turtles seem to be particularly good at noticing green light, and these nets cut down on turtle bycatch by 64%. The current study builds on those findings, examining whether other marine animals could benefit from the same idea.

It turns out, they would. The authors worked with small-scale grouper and halibut fisheries in Baja California, Mexico, as the area is known for its large populations of turtles and other large marine species. They deployed 28 pairs of nets, one of each being equipped with groups of green LED lights every 10 meters. The team gauged their efficiency by identifying and weighing the animals each net captured overnight.

Nets outfitted with lights captured 63% less bycatch overall. Per species, they reduced bycatch by 51% for turtles, 81% for squid, and 95% for elasmobranchs (sharks and rays) — the last one being the most “gratifying” result for the authors, as shark bycatch in the Gulf of California is “a huge issue”.

Fish capture was not affected by the lights. However, the LEDs cut down on time wasted by fishermen on hauling and unloading bycatch, and on untangling the nets, by half. The only drawback so far, according to Senko, is the upfront installation costs of the lights: around $140 per net. Some fisheries, especially those in poorer areas such as Indonesia and the Caribbean, simply can’t afford this price per net, they add. The team is toying with using fewer lights and having them be solar-powered rather than battery-powered to reduce some of these costs. Meeting the needs of fisheries is essential for the success of this project, as they are the ones who will decide on using the LED nets or not.

Exactly why some animals seem to avoid lights, and why they do so more than others, is still up for debate. While it is possible that some species’ better eyesight helps them perceive the lights more clearly, it’s very unlikely that this is the cause — any species with sight can see these lights, after all.

The paper “Net illumination reduces fisheries bycatch, maintains catch value, and increases operational efficiency” has been published in the journal Current Biology.

Study finds new genetic editing powers in squids

Usually described as elusive, squids are highly skillful animals. They have bilateral symmetry, gills that are used for breathing, and skin covered with chromatophores, pigment-containing and light-reflecting cells through which they can camouflage to the environment.

Credit Wikipedia Commons

Now, scientists have discovered another surprising feature of squids. Not only they can edit their RNA or genetic instructions within the nucleus of their neurons but also within the axon, which are the neural projections that transmit electrical impulses to other neurons.

DNA and RNA are the most important molecules in cell biology, responsible for the storage and reading of genetic information that underpins all life. While DNA replicates and stores genetic information, RNA converts the genetic information contained within DNA to a format used to build proteins.

Back in 2015, a group of researchers discovered that squids were able to change their RNA instructions, fine-tuning the type of proteins to be produced. Now, they were able to dig deeper into their work and observe the edits outside the nucleus of the cell of the squids.

“We thought all the RNA editing happened in the nucleus, and then the modified messenger RNAs are exported out to the cell,” says Rosenthal, senior author. “Now we are showing that squid can modify the RNAs out in the periphery of the cell. That means, theoretically, they can modify protein function to meet the localized demands of the cell.”

In the past, Rosenthal and his group of researchers also worked in cuttlefish and octopus, which they discovered also rely on the editing of RNA to diversify the proteins they produce in the nervous system. Alongside the squid, this group of animals is known for its sophisticated behavior.

The findings could have implications not only for squids but also for humans, as the axon dysfunction is associated with neurological disorders. Researchers hope the study will help biotech companies use the RNA editing process in humans for therapeutic benefits.

“The idea that genetic information can be differentially edited within a cell is novel and extends our ideas about how a single blueprint of genetic information can give rise to spatial complexity. Such a process could fine-tune protein function to help meet the specific physiological demands of the different cellular region,” the researchers wrote.

The paper was published in Nucleic Acids Research.