When i take stock of my life as a fisherman, the particular species that torments me is Atlantic cod. Back in the early 2000s, I began making an annual winter cod trip to Gloucester, Massachusetts. In spite of all I’d read about codfish heading toward extirpation, I nearly always ended up with good-size brown-and-yellow-speckled cod whenever I’d drop a line to the bottom. But as the years went by I began to notice that the codfish started getting progressively smaller and that the sport-fishing fleet was converging on an ever-diminishing area. The oceans still seemed full of fish, but in fact the codfish range was shrinking and the population was making something of a last stand.

This, it turns out, is a phenomenon that the marine ecologist Daniel Pauly has identified as “the shifting baseline syndrome.” Simply put, when we possess no absolute measure of natural abundance, our minds use a sliding scale and incorporate what can be enormous declines within a redefinition of “normal.” This continual forgetting and recalibration compels fishermen to forever move on to new grounds. As Pauly put it to me, “Even when fisheries seem to be stable, they are slowly expanding.” Marine protected areas are the flip side of this constant expansion. By closing areas to fishing, we establish a baseline against which all our deductions can be finally measured.

As I started thinking more and more about the possibility of not fishing, I decided to visit the Channel Islands marine reserve network. It comprises the first group of no-fish areas created in California and has the most data available for analysis in the post-sanctuary era. Since 2003, around a quarter of the water around the Channels has been closed to fishing. Now, more than a decade later, I wanted to see if shutting down that much ocean could have the effect that scientists hoped it would.

Just before dawn, I boarded the Cobra in the town of Oxnard. In former times I might have fished off Laguna Beach or Marina del Rey. But now with reserves blocking much of the grounds to the south, Oxnard was my port of last resort. Other fishermen had the same idea. A small armada took shape in the penumbra when we reached the fringe of a kelp forest a little ways outside of a marine reserve near Anacapa Island.

As the Cobra slowed to prepare for a first drift, I grabbed a live squid in the bait well. After hooking it through, I flipped it out and cringed as it almost dropped into the cockpit of a sleek private yacht cutting us off stern-side. “Hey,” one angler on our boat yelled. “Get outta the way!”

Closing areas to fishing doesn’t necessarily reduce the amount of fishing that goes on. In fact, it may crowd more and more fishermen into a smaller space. This displacement effect, some theorize, could possibly cause a net loss of fish if you were to take into account areas both inside and outside the reserves. Amid the crowding of boats off Anacapa, it was easy to think that something like that was happening.

When the networks were designed, the long-term growth of the fish population was of greater concern than the crowding of fishermen. Steve Gaines, dean of the Bren School of Environmental Science & Management at the University of California at Santa Barbara and one of the driving forces behind the Channel Islands reserve, explains the theory of the networks this way: “Imagine if human babies when they were born were tied to helium balloons and then we let them float for three or four days until the balloons deflated. Wherever those babies ended up would be where they would spend the rest of their lives. That’s the way it is with fish. Because larvae drift, one reserve can enrich other reserves even though they’re widely separated.”

A decade later, the first comprehensive results are starting to emerge from scuba surveys. Jenn Caselle, a research biologist also from the University of California at Santa Barbara, has logged thousands of dive hours in the same cold water and kelp I experienced in Monterey. She’s found a noticeable change there, particularly around Anacapa Island, where I was now fishing. “The important message from the Channel Islands over ten years,” she says, “is that the fish inside the reserves are increasing. But here’s the key point. The populations of many fished species outside the reserves are also increasing — not as fast, but they’re increasing. This is really important because it was feared that the redistribution of fishing effort could cause scorched earth outside the reserves. That’s not happening.”

All those extra boats that were wedged against the Cobra were apparently not doing as much damage as one would expect. Indeed, the fishing I experienced off Anacapa showed no sign of diminished returns. Once we’d cleared the stern of the private yacht and I flipped my squid through a pile of kelp, line started peeling off my reel. I leaned back and set the hook. Five minutes later, what I thought of as an impressive fish — a nearly 3-foot-long lilac-and-silver white sea bass — came to the gaff and hit the deck with a thud. I was certain my fish was going to win the jackpot, the pool of money anglers contribute to at the beginning of the day that is awarded for the biggest catch.

Evidence like Caselle’s isn’t good enough for some critics. Ray Hilborn, a professor of aquatic and fisheries science at the University of Washington who’s frequently cited by fishermen as a counterweight to the “enviros,” claims there’s no evidence that the sanctuaries are having a comprehensive effect. Hilborn had taken part in the establishment of California marine reserves and found the science guidelines lacking in academic rigor. “If they had done it correctly,” he says, “there would have been adequate control groups, like with any experiment. They would have set up three reserves and three non-reserves and then compared the fish in each after five and then ten years.”

But Caselle argues that a control for an experiment the size of the Channel Islands network is an impossibility. “The hypothesis is that the total effect of a network is greater than the sum of its parts,” she says. “But that is very difficult to measure. That would require having another region that is similar in all ways to Southern California but without marine protected areas. Essentially, there are no controls for entire networks.” In other words, the entire California approach to linking its fragmented coast is a leap of faith. A leap of faith where the default is not fishing instead of fishing.

My “big” 30-inch white sea bass was soon trumped by another white sea bass a good 6 inches longer. Then came a bigger one. And an even bigger one. And finally a fish so big that my posing for a group photo with the other anglers and their fish at day’s end was an embarrassment. For good measure, just as we were gearing up to head home, the captain eased the Cobra right up to the edge of the reserve, which caused an angler in the stern to shriek. She had hooked a halibut the size of a radial tire.

Perched on equipment that provides a live feed from an underwater rover, Elsa watches over Tim Maricich’s wheelhouse.

Were all these fish the result of the reserve? Or was it just a good day, as can happen, even when there aren’t that many fish around? It cannot yet be scientifically documented. Since many fish that are specifically protected by the reserves, like rockfish, can live many dozens of years, it may be a long time until we know the extent to which reserves populate other fishing grounds. By the end of the day, when the mate cleaned our catch and the dozen-odd fishermen aboard the Cobra all had a bag or two of fillets to show, there seemed to be a grudging feeling that the Channel Islands experiment had shifted something. As we motored back to port, a retired chef who’d been fishing next to me muttered, “I’ll tell you what, if it wasn’t for these closures, there wouldn’t be any fish at all.”

This thought stayed with me as I made my way to the airport. After boarding a plane I checked my phone before shutting it down for the trip back east. Atop the headlines was the news that the National Oceanic and Atmospheric Administration had closed the entirety of the East Coast from Provincetown, Massachusetts, to the Canadian border to both commercial and sport cod fishing — at least until May, in an effort to reverse declining fish populations in the Gulf of Maine. These were grounds I’d helped deplete over the past decade. After the latest stock assessment it was revealed that cod had dipped to an even lower level than had previously been assumed. The remaining stocks from Cape Cod to the Gulf of Maine, a population upon which colonial New England built its economy, were now reported to be between 3 and 4 percent of what would be required to have a sustainable fishery.

As I considered this news, I thought how the fishermen of California might have avoided a similar fate. The Monterey Bay Aquarium’s Seafood Watch program recently surveyed the range of fisheries off California and moved many of the state’s groundfish species off its red “Avoid” list. In the decades ahead, commercial fishermen might enjoy rebuilt runs of rockfish and lingcod, surging runs of white sea bass and squid, all of them dashing through the regrown kelp in pursuit of sardines and anchovies that are also, apparently, on the rebound.

With the spring migrations coming on, the usual time I’d head to Gloucester for cod, I thought about what I might do instead. Was there something else I could fish? Maybe mackerel would swing through our waters as they once did in my youth but now only do on occasion. Maybe the blackfish would make an appearance if they hadn’t been hit too hard by lobstermen whose Long Island Sound lobster had grown scarce. Or maybe I’ll just hang it up and not fish at all this season.