When I was growing up, my family lived in New Orleans for several years, on the north shore of Lake Pontchartrain. One of my father’s friends had a boat, and he liked to take it out shrimping. My dad and I would often join him and his son.

I loved those early morning boat trips (except for the time that I got very seasick — probably my fault for snacking on Fritos — and the trip that I’m about to tell you about). The lake was so big that you could barely see the shoreline.

On one occasion, our nets were coming up empty, so my dad’s friend steered the boat toward the mouth of the lake where it meets the Gulf of Mexico and ventured into a cove where he hoped to find some shrimp. Soon, the boat started dragging. We feared that the net had gotten snagged on the bottom of the lake. But when they winched it in, the cause turned out to be quite a bit scarier for my 10-year-old self.

The boat had gone right over a school of stingrays, which had probably ventured into the lake from the Gulf, and our net was full of them. As the net came up, it looked like they were going to spill into the boat. My dad and his friend struggled to release them without damaging the boat or the fishing equipment, but eventually they had no choice but to cut the net away.

I watched from the prow as those ghostly stingrays spread out beneath us, silently gliding away from the hapless weekend fishermen who had inadvertently disturbed them.

Drawing food from the sea is one of the most fundamental interactions that we can have with the our oceans, and I’m glad that I have those early experiences in New Orleans to draw upon. The stingray incident taught me a respect for the ocean and its creatures — and a concern for how we interact with them — that sticks with me today.

The fish we choose to eat — and the way we fish for them — can have a tremendous impact on our oceans. As part of a personal goal to eat healthier, I’m trying to increase the amount of fish in my diet. It’s a lean protein with great health benefits. But there are risks, as well: Some types of fish can be contaminated with mercury and PCBs, and sometimes seafood is harvested in a way that’s bad for the oceans.

A new Sustainable Seafood Guide from the Natural Resources Defense Council can help me — and you — make better choices about what we eat. It provides seven basic guidelines to follow when shopping for seafood or ordering at a restaurant, as well as specific advice about America’s five favorite types of seafood, from shrimp to tuna to fish sticks.

I was a little disheartened to see that many of my favorite varieties of fish — grouper, halibut, orange roughy, cod — had landed on the recommended “avoid” list. (Pacific cod and halibut are OK, but the Atlantic varieties are badly depleted.) I was aware of the overfishing problems that many species face, but this put it in pretty stark terms.

Today is the first-ever World Oceans Day, designated by the United Nations as an occasion to celebrate and protect the world’s oceans. And there are certainly a lot of problems facing our seas — overfishing, habitat destruction, acidification, water pollution, giant trash vortexes in the Pacific … the list goes on.

We might not be able to tackle all of those big problems all at once. But as NRDC’s Laura Pagano suggests, one way that each of us can make a difference right now is to make smarter choices about the seafood we eat and understand its impact on the oceans.