Fishers remove more than 77 billion kilograms of wildlife from the sea each year. Scientists fear that continuing to fish at this rate may soon result in a collapse of the world’s fisheries.

Consider the example of the bluefin tuna (蓝鳍金枪鱼), which is known for its delicious meat. High demand for this fish has threatened its population, Today, there are only around one-quarter as many bluefin tuna as there were in 1970.

Since about that time, commercial fishers have caught bluefin tuna using purse seining and longlining. Purse seine fishing uses a net to bring fish together and then trap them by pulling the net’s drawstring. Longlining is a type of fishing in which a very long line of up to 100 kilometers is set and dragged behind a boat. These lines have thousands of baited hooks (诱饵) attached to smaller lines stretching downward.

For fishers, catching so many at once is very profitable. However, over time this type of fishing leaves few fish of a particular species left in the ocean. If a fish population becomes too small, it cannot easily replenish itself, or grow back to or close to its original size.

There are ways to fish sustainably. In many traditional cultures, people have fished sustainably for thousands of years. In the Philippines, for example, the Tagbanua people have traditionally used fishing practices that maintain fish populations. They continue to do so today. They set aside certain areas as protected spots in which fishing is forbidden, When they do fish, these traditional fishers primarily use hook-and-line methods.

Another way to prevent overfishing is to simply stop eating fish and other seafood. Dr. Sylvia Earle, a famous and well-respected marine (海洋的) scientist, has taken that step. She suggests people need to take a break from eating seafood until we learn to maintain healthy fish populations.

“I personally have stop ped eating seafood,” Earle says. “I know that every fish counts at this point.” Fish, she says, are critical to maintaining the health of ocean systems, which in turn “make the planet work.”

It has now been one year since The Ocean Cleanup made history by cleaning up the first of the plastic from the Great Pacific Garbage Patch(垃圾带). And now, its researchers are turning the waste into designer sunglasses. Not only are the stylish glasses made from the plastic collected, but the earnings go toward helping support the nonprofit so they can continue cleaning up the ocean.

The new glasses are the first product to be created from the recovered ocean waste, but The Ocean Cleanup website says it will not be the last. Back in October 2019,after years of research, The Ocean Cleanup project announced that their System 001/B had successfully collected plastic waste from the garbage patch. The system uses the natural forces of the ocean to gather plastic in the garbage patch, a process that was first brought up by Boyan Slat back in October 2012.

Together with famous designer Yves Behar, and Safilo, The Ocean Cleanup worked to create sunglasses that could produce a feeling or memory of the ocean, reminding people where they came from and what they are protecting. The frames（框架）of the new sunglasses are made from the recovered ocean pollution. Because the joining points have also been specially designed, they can very quickly be taken apart for recycling.

Although the sunglasses cost $199 a pair, all of the money earned from them will be used to fund the nonprofit' s operations. For every pair sold, the organization will be able to clean 24 football-fields-worth of ocean garbage. And since the glasses went on sale earlier last week, supporters have already funded more than 133 , 100 football fields of garbage.

“When every pair is bought up from the first batch（批）of sunglasses, we can then clean 500,000 football fields worth of plastic,” says the website. “That means we can use this garbage to clean more garbage: going full circle, over and over, until we have achieved our purpose of clean oceans.

Ocean water can be used to cool buildings. This idea could help cities reduce their carbon footprint and slow climate change. Although plentiful, ocean water is too salty to drink. But it could serve as an important and still largely untapped resource which was known to few people for many coastal cities. The idea came to Zi Zhang shortly after she moved from Michigan to Hong Kong a few years ago to get a PhD in engineering.

In 2013, Hong Kong built a system that used seawater to cool part of the city. The system pumps cold seawater into a plant with heat exchangers. The seawater absorbs heat to chill (冷却) pipes full of circulating water. That chilled water then flows into buildings to cool their rooms. This type of system tends to use far less energy than typical air conditioners. Zhang wondered: How much water and energy had this way saved Hong Kong? And why weren’t other coastal cities doing this? Zhang and her team set out for answers. The group focused on Hong Kong and two other big coastal cities: Jeddah and Miami. The idea was to see what it might look like if all three adopted city-wide saltwater systems. The cities’ climates were quite different. But all three were densely populated, which should minimize some costs.

All three places would save lots of freshwater, the researchers found. Miami could save 16 percent of the freshwater it uses each year. Hong Kong, with more non-drinking-water needs, was saving up to 28 percent. Estimated energy savings ranged from just 3 percent in Jeddah to 11 percent in Miami. These savings came from the more efficient saltwater air conditioning. Also, the cities would need less energy to treat salty wastewater than they have been using to treat sewage now.

Though costly to build, saltwater-cooling systems could pay off in the long run for many cities. And because these systems use so much less electricity, they’re greener and emit (排放) less carbon-rich greenhouse gases. Scientists refer to this as a type of decarbonization (脱碳).