Excerpted with permission from A Naturalist Goes Fishing: Casting in Fragile Waters from the Gulf of Mexico to New Zealand's South Island, by James McClintock. Available from St. Martin’s Press. Copyright © 2015. (Scientific American and St. Martin’s Press are part of Holtzbrinck Publishing Group.)

“A veteran scientist and adventurer, Jim McClintock writes with passion and knowledge of his love of fishing within some of the most beautiful yet threatened waterways on Earth. He issues a stark reminder of what’s at stake if we fail to replace fossil fuels with clean energy sources.”—Robert Redford

The bull redfish was probably close to forty pounds, large by Chandeleur Islands standards. The fish had beaten the odds—one of the last survivors of twenty-five million eggs spawned by its mother over a single breeding season. The vast majority of the eggs had not been fertilized or had been carried by currents to shallows warmed by Louisiana’s afternoon sun. Some had been tossed by waves onto the shore to dry among the detritus. Those that had developed into larvae were largely consumed by zooplankton and juvenile fish.

The redfish had grown quickly in its first year—reaching a foot in length by gorging itself on the rich beds of polychaete worms buried in their homemade tubes in the soft sand or by chasing  down small crustaceans that darted in and out of sea grass blades. By three years of age, the fish probably weighed an impressive eight pounds and had shifted its diet to big blue crabs—its favorite—along with penaeid shrimp, small croakers, mullet, menhaden, and lizardfish.

As the seasons piled up, the big male attained “bull” status, defined in measure as thirty-five inches or longer from nose to tail. Its foraging range and feeding habits became routine, so much so that the white, pink-tailed plastic jig attracted the fish’s attention. After the slightest hesitation, the tantalizing herky-jerky movement of the lure triggered an irreversible burst of neuromuscular activity. The bull redfish struck.

“Fish on!” I yelled in the general direction of my fishing buddy and younger brother Pete, who was seated behind me in our twelve- foot skiff. Pete smiled despite the lightly falling rain and a southwest wind that stirred the water in the shallow cut between the islands. A deep tug followed by strong head wags ruled out a speckled sea trout or ladyfish. “I think it might be a big red!” I shouted. Pete reeled in his line and stowed his pole using the clips on the aft side of the skiff. We both knew the fish would dictate the terms of the fight. If one didn’t take immediate action, a fish this size hooked on medium tackle strips a good bit of line from the reel and invariably escapes, either from the line-breaking tension caused by setting the drag in a desperate attempt to turn the fish or, just as often, from running smack out of line.

Pete reached back, grasped the engine’s throttle in his left hand for balance, and used his right hand to pull-start the twenty-five-horsepower outboard. The engine, still warm from a recent run, sputtered to life after a few quick tugs. Knowing that from his position Pete couldn’t see in which direction to head the skiff, I stood at the bow, fishing pole in hand, and pointed in the general direction the fish had surged. Clicking the engine into gear, Pete gently gunned the throttle and nudged the skiff forward as I reeled line. After what had seemed an interminable stretch of anticipation, we were underway, the big fish holding tight to the bottom, still hooked, still unseen.

Les Îles de Chandeleur lie thirty miles off the coast of Louisiana, delineating the southeastern-most corner of this decidedly Cajun territory. A portion of the Breton National Wildlife Refuge, the fifty-mile chain of uninhabited islands is a naturalist’s dream. The landscape consists of low-lying, densely vegetated barrier islands built of sediments washed down the Mississippi long before the Army Corps of Engineers began to dam up the river. In stark contrast to the lack of relief of the islands, the sky and the horizon are as immeasurable as any I have seen in Florida, Montana, or Wyoming. The grandeur sets the stage for jaw-dropping sunrises and sunsets, and during the summer, afternoon thunderheads open up. Thousands of once-endangered brown pelicans and magnificent frigate birds nest among black mangroves, the frigates often soaring in huge spirals, effortlessly riding the thermals until they are but specks in the sky.

I have visited these islands with eleven friends to fish for speckled sea trout and redfish just about every summer or fall for the past fifteen years. Some in our group have been coming more than twice as long, a testament to the addictive nature of this annual pilgrimage. Each year, we drive from Birmingham, Alabama to Biloxi, Mississippi, squeezed into sedans and vans brimming with fishing gear. Arriving at Point Cadet Marina, nestled under the belly of the Golden Nugget Biloxi Casino (formerly the Isle of Capri Casino, which was heavily damaged in 2005 by Hurricane Katrina), we board the VI, an oddly named, 127-foot live-aboard ship owned by Southern Sports Fishing Inc. and captained by Robbie Thornton. Between the twelve of us, more than sixty rigged fishing poles are secured between paired holes cut in wooden boards lining the underside of the open ceiling on the outside back deck. Tackle boxes are slid below benches. Beer is iced down in large coolers. Duffle bags stuffed with toiletries and clean clothes are tossed on bunks below deck (so as to best lay claim to sleeping quarters farthest from noisy engines or those who snore). By late evening, alarm clocks set, we settle into our bunks. Around midnight, Robbie fires up the ship’s engines, and the first mate unmoors the ship. Four hours later, the ear-jarring racket of anchor chain disrupts our sleep. Alarms ring. Half asleep, we climb from our bunks to dress, pulling on long-sleeved fishing shirts. Sipping dishwater coffee, we shovel down breakfast while the captain and first mate lower our skiffs by crane from the ship’s upper deck, plopping each into the still-dark waters of the Gulf of Mexico. The small skiffs, each provisioned with gas, net, cooler, and life jackets, form a bobbing line against the early dawn sky, an umbilicus connecting our ship to the sea.

“He’s running again!” I warned Pete over the whine of reel drag and rumble of engine idle. We had followed the fish for close to forty minutes. Hard rain, stiff winds, and a falling tide had conspired and left us wet and chilled. The only good news was that I had caught a glimpse of the fish. It was definitely a big red, its upper body carpeted in a mosaic of coppery red scales. The fish had to be at least three feet long, with a broad muscular girth that spoke to its bulldog strength. The fish slowed. Maybe it was tiring. I lifted my rod tip and pulled back slowly and steadily and reeled in line as my rod descended. Again and again, lift, pull, reel. With mounting excitement, Pete and I watched the fish’s tail fin break the surface near the skiff. Then, as if punctuating the end of a sentence with a deft tail kick, the bull red broke free and vanished.