NEW ORLEANS (AP) — Something good appears to be happening to our redfish in the shallow interior marshes: They are getting bigger.
Marsh anglers who once were surprised by hooking into an 8-, 10- or even 15-pound redfish are now finding this a common experience.
Wide-bodied reds that once were called “bulls” are now living, eating — and being caught — in shallow ponds and interior bays that were previously home to smaller fish. And that’s not just the fish stories from amateurs, the type of anglers who tend to add five pounds to everything they land. The news also is coming from the pros.
“I’ve definitely noticed an increase in the size of redfish we’re catching in the estuary,” said Mark Brockhoeft, head of Myrtle Grove-based Big Red Outfitters. “This is the most big fish we’ve seen consistently in the shallow marsh in 15 years.
“There’s just no doubt about it. The redfish in the shallow estuaries are just much bigger now, for whatever reasons.”
But what are those reasons? What can cause the size structure of a population of fish to outgrow its traditional framework. For a generation, biologists told anglers that the life cycle of a redfish was simple: They lived in interior marshes until they reached about 25 to 27 inches — usually reached around the age of five. At that point they moved offshore to join the spawning stock, where they live out their lives, never to return to the shallow marsh again.
So how can reds longer than 27 inches now be such a common catch in those shallow estuaries?
While there is no new research to explain the changes (or even confirm the increase in size), biologists say the answers probably can be traced to three factors: regulations, climate change and coastal erosion.
In 1985, responding to evidence the species was being overfished inshore and off, the daily limit was reduced from 50 to five, and the species got its first-ever size limits- a 16-inch minimum and one fish longer than 36 inches, which later was reduced to one longer than 27 inches. Commercial fishermen were given a quota, but a few years later that fishery was closed and the species was given gamefish status.
“All those moves dramatically reduced fishing mortality, which increased the number of fish left in the water,” said Harry Blanchet, coordinator of coastal finfish programs for the state Department of Wildlife and Fisheries. “Since your large fish are a smaller percentage of the total fish in a population when you increase the total population, you have more big fish.”
Creel surveys quickly showed the impact. Before 1985 the average size of a redfish kept by anglers was 12 inches; since then it has averaged between 16 and 18 inches.
So, more fish, more big fish.
Climate change has resulted in shorter and milder winters. Louisiana hasn’t had a serious fish-killing freeze since 1989. Because they are cold-blooded animals, a fish’s metabolism increases with water temperature, which means they eat more often, and grow at a faster rate.
“It’s been warmer in the so-called cold-weather months, and that means they probably are eating more, and more frequently,” said Blanchet. “The more they eat, the faster they grow.”
The disintegration of the marsh may have had the twin impacts of providing more food and closer proximity to higher salinity rates, something larger redfish prefer.
Fisheries scientists have long pointed out that as the marsh erodes it releases large amounts of nutrients into the estuary, priming the food-chain for species such as shrimp, crabs and small finfish such as menhaden. All those species happen to be prime redfish groceries.
“So you have warmer winters and more food which means you’ll have a faster and longer growth rate,” Blanchet said.
Size and age are factors when a redfish reaches sexual maturity and becomes “spawning age,” Blanchet said.
“We find 3-year-old fish out with the spawning stock, and we find fish over 5 years old in the marsh,” Blanchet said. “There is no definitive age for sexual maturity. If a fish develops more quickly, that is, if it’s got the size of a typical 5-year-old fish at the age of 3, it’s probably ready to spawn.”
Summarizing, Blanchet said all these suggestions are just that — best guesses based on available science and experience. And the guess is offered to measure a size increase that, so far, has not been verified by research.
“Those large reds are a difficult fish for us to sample because they are hard to catch in our equipment, so we don’t have data to support what fishermen are seeing,” Blanchet said. “But I’m not saying I don’t agree with what the fishermen are saying. I think you see it in the size of fish being brought in at rodeos and tournaments.”
Anglers like Brockhoeft find plenty of logic in the suggestions offered to support the increased size. He has been in the marsh chasing reds — and specks, shrimp, cockahoes and other critters — for most of his 55 years. And he can recognize change when he sees it.
“Believe me, these redfish we’re catching in the estuary are as big as we’ve seen in 15 years,” he said. “Our redfish are definitely getting bigger.”
 
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