Pollution and Invasive Fish

If you see litter on the ground anywhere in the Hawaiian Islands, there’s a good chance it will eventually wash into the ocean. The Hawaiian Islands are near the Great Pacific Garbage Patch where floating plastic from all around the Pacific is gathered together by ocean currents. Many fish, turtles, and sea birds die from eating plastic garbage, or get caught in abandoned fishing nets left floating in the ocean.

Plastic doesn’t just harm sea life. Microscopic plastic gets into all of us through seafood, sea salt, the air, water, and any food or drink packaged in plastic. A 2019 study estimated that people eat an average of 5 grams of plastic a week. That’s about the same as a credit card worth of plastic every week! Imagine eating almost half a pound (250 g) of plastic a year.

Unseen chemical pollutants are also a problem. Runoff from agriculture and urban areas put contaminants in the water. Be aware that any chemical you use, like cleaning products, herbicides, and fertilizers, and petroleum products will likely eventually end up in the ocean. Try to choose natural non-toxic options when possible.

Invasive fish like the tilapia tend to be more tolerant of polluted water than native fish. In the 1950s Hawai‘i’s State Fisheries Agency introduced four species of tilapia fish (Oreochromis mossambicus, O. macrochir, Tilapia rendalli, and T. zillii) as baitfish and to control aquatic vegetation. They quickly multiplied out of control and displaced native fish from their habitat. Tilapia have the advantage of being very adaptable. They can survive in brackish salty water, and even heavily polluted water. Tilapia have alternately been introduced for aquaculture, and targeted for eradication in the wild.

Other introduced fish like the peacock grouper, Chinese catfish, and minnows also cause damage to the native ecosystem. There are over 50 species of alien fish, invertebrates, reptiles, and amphibians. Some were introduced on purpose for sport fishing, and aquaculture. Some alien species were unintentional introductions. It’s important to never release aquarium fish into the wild.

The best way to keep plastics out of the ocean is to not use them. Choose a natural biodegradable alternative when possible, or consider doing without. The same applies to toxic chemicals and anything we buy in general. Consider the entire life cycle of the things you purchase. Ask, “where will this go after I’m done with it?” Sometimes, it’s better to just live with less.