BIOLOGISTS CONSIDER SHARK DEPREDATION

 

Shark depredation—the act of sharks stealing fish from anglers or commercial fishermen—is nothing new.

Ernest Hemingway wrote about sharks “apple coring” bluefin tuna—attacking a hooked fish so relentlessly that an angler was left with little more than a head, a tail, and a near-fleshless backbone in-between—in the mid-1930s, and when I began fishing for cod from Rhode Island party boats three decades later, it was pretty well understood that we’d lose a few on every trip to the sharks that would inevitably be attracted to the struggling fish we reeled up from the ocean’s floor.

Offshore sportfishing is a relatively new sport, not much more than a century old, but it’s a pretty good bet that the fishermen who first set a net or threw a spear into the ocean, hoping to drag some food from the sea, learned first-hand about shark depredation, long before anyone gave it a name or developed the alphabet needed to record its occurrence.

Still, shark depredation has been getting a lot more press during the last few years, and there is little doubt that depredation events are becoming more common, both in northern and southern waters.

The big question is “Why?”

A team of biologists set about trying to answer that question.  The result was the recent paper, “Characterizing a century of shark depredation in US Atlantic recreational fisheries,” which was published in the April 2026 edition of the ICES Journal of Marine Science.

The researchers came up with a correlation between shark abundance, prey fish abundance, and angling activity that suggests why rates of shark depredation have varied over the years, which seems to make intuitive sense and corresponds with what I’ve observed on the water over the past 60 or so years.

Early in the paper, its authors note that

“At its essence, shark depredation is the result of human-wildlife overlap; in this case, spatially and temporally dynamic overlap between recreational anglers and sharks competing for a shared resource.  Navigating the challenges associated with recent increases in shark depredation (real or perceived) requires a broader understanding of how this overlap has evolved over time.  Therefore, we present a conceptual model incorporating historical information to broadly characterize a century of overlap between US Atlantic recreational anglers, target fisheries species, and sharks…  [citations omitted]”

One of the more interesting aspects of the analysis is that shark depredation, along with the factors that cause it, ebbs and flows over time; it does not follow a consistent trajectory. 

In the beginning—meaning the beginning of the 100-year span analyzed in the paper, not the beginning of all interactions between fishermen and sharks—depredation occurred, but there wasn’t too much overlap between anglers, sharks, and their shared target species in the quarter-century between 1925 and 1950.  Angler populations were certainly far lower than they are today, and target fish populations, being under far less pressure, were almost certainly much higher.  But what might be the most surprising aspect of the latter half of that period is that the shark population was probably somewhat depressed, at least in the waters off Florida, where some of the highest levels of shark depredation reportedly occur today.

That was due, as the paper notes, to the need to find a substitute for cod liver oil, which was then one of the most-used vitamin supplements.  Once the start of the Second World War, and the threat of German U-boats, cut off cod liver oil shipments from Europe, shark livers, processed at a plant in Port Salerno, Florida, provided a viable substitute.

It’s probably important to note a description of the then-new commercial shark fishery that was quoted in the paper:

“Thus the shark, a pest and a menace to Florida fishermen and sport lovers, the scourge of Florida waters, is being transformed into one of the most valuable creatures of the sea,  [emphasis added]”

because when we hear fishermen complain about current levels of shark abundance, we often hear them say that sharks “need to be controlled,” or that shark populations are “out of control.”  The supposed overabundance of sharks is blamed on the National Marine Fisheries Service’s efforts to manage shark populations, with one charter boat captain whining that

“The sharks have been protected for decades, and I believe it’s time that we need to control these predators as their population is spiraling out of control.”

But the early-1940s comment about sharks being “a pest and a menace to Florida fishermen and sport lovers” confirms that there is nothing new about shark depredation; it was going on long before NMFS began regulating shark landings, and long before “depredation” became the buzzword that it is today.

In the next quarter-century—1951 through 1975—the paper suggests that the overlap between anglers, sharks, and the various prey species increased substantially.  The number of recreational fishermen increased as the typical worker had more leisure time, as well as a better selection of affordable fishing boats, while the availability of fish traditionally targeted by recreational fishermen began to decline due to increased landings, largely by the commercial fishery; at the same time, shark abundance was generally stable, as the commercial fishery declined while recreational shark fishing, spurred on by the book, and later the movie, Jaws, became more and more popular.

This was the era in which I was born, began angling, saw my first recreationally caught sharks, and had my first experiences with shark depredation.  It was also the time when I first experimented with recreational shark fishing, and the time that created my personal baseline for shark depredation.

At that point, sharks were generally cursed at by anglers when they stole a tuna, billfish, or cod, but shark depredation was not the cause celebre that it is today.  It was merely a nuisance that fishermen learned to live with when they ventured out onto the sea.

That being said, it could easily be argued that today’s discontent over shark depredation was born in the third quarter-century defined in the paper, the years 1976 through 2000.  They were years when the angling population continued to increase, while the populations of both sharks and the various target fish species were both in decline.  There was relatively little overlap between the three groups.  In fact, according to the paper’s authors, the years between 1976 and 2000 resulted in the least overlap of any period during the past hundred years.

As the paper observes, during this period,

“commercial shark fisheries were explored as an underutilized resource, and public interest in recreational shark fishing continued to grow.  Expanding trade relations with China during this period also offered massive new markets for US seafood exports, including shark fins.  Consequently, commercial shark landings escalated by an order of magnitude, from 135 tons in 1979 to 7172 tons in 1989, yet it wasn’t until 1993 that the first fishery management plan for US Atlantic sharks was enacted.  By then, most primary targets of commercial shark fisheries…were overfished…  [citations omitted]”

Some species of shark saw their abundance fall to historic lows.

This was the time when I became an active recreational shark fisherman, catching, killing, and eating my first sharks in the late 1970s, then buying my first (more-or-less) offshore-capable boat in 1982, catching my first sharks from that boat a year later, when I also ended up moving from my original home in Connecticut, where fishing was restricted to a shark-starved Long Island Sound, to the South Shore of New York’s Long Island, a move motivated by my desire for ready access to the ocean and the sharks and tuna that roamed within.

During those years, I became an active tournament fisherman, and saw anglers fishing from my boats place a number of prize-winning sharks on the scales.  But I also saw some species of shark fall into notable decline, dusky and sandbar (“brown”) sharks foremost among them.  The big tiger sharks that were once relatively common off New York during the summer became far less abundant, and even the shortfin mako, the most popular species in our local shark fishery, appeared to grow somewhat scarcer and trend smaller in size as the 20^th Century reached its end.

Anglers became accustomed to an ocean where sharks were fewer and farther between than was the case in previous decades.

Thus, they were mentally unprepared for what happened over the last 25 years.

The paper refers to the years 2001 through 2025 as a time of

“Greatest overlap and lifting baselines,”

when

“there are more anglers than ever before, shark populations are rebuilding following three decades of management, and many target fishery species are recovering from overfishing.”

Dr. J. Marcus Drymon, the lead author of the paper, previously characterized what can happen next as a sort of “lifting baseline” situation, in which

“Instances where populations have been overfished and then rebuilt can create a perception of overabundance.  When the species that’s recovering is a predator, that can lead to human-wildlife conflict.”

That’s arguably what we’re seeing with shark depredation today.

Still, the shark depredation issue can’t be ignored, because sharks do steal fish from anglers, and anglers do get upset when that happens.

The paper, relying on input from various sources, identified 22 species of shark that engage in depredation, and 51 target fish species that suffered from the events.  The depredation events involved 207 different combinations of shark and target fish species, with bull sharks and sandbar sharks named as the most frequent depredators.  Those figures probably underestimate the number of possible shark/target fish combinations that actually occur, as I recall that my early recollections of depredation on the Rhode Island cod boats involved blue, shortfin mako, and dusky sharks, although duskies were not listed as one of the reported cod depredators in the study.

Perhaps most significantly, the paper stated that

“There are no ‘silver bullet’ shark depredation solutions that will work across all of the fishery scenarios identified in our analysis.  Ideally, any approach should simultaneously maximize access to target fishery species while minimizing shark interactions.  Yet, in reality, potentially available mitigation options may only marginally reduce conflict, not eliminate it.  Depredation mitigation options currently include three primary mechanisms: (1) using technical/physical deterrents, (2) modifying fishing behaviors, or (3) reducing shark populations.”

It notes that

“researchers are testing the efficacy of technical/physical deterrents with promising results,”

while also observing that

“Shark population reduction, either through targeted removal or optimizing sustainable harvest of sharks, is often proposed by anglers as the preferred mitigation option,”

although such population reduction might prove impractical because

“Killing prohibited species…is illegal, while targeted removal of authorized species…without widely marketable products is wasteful and inconsistent with US fisheries law.”

As an angler who has fished on every coast of the United States, and is more than familiar with the Atlantic coast shark fishery and other Atlantic coast fisheries, I would argue that the second option, modifying fishing behaviors, probably holds the greatest promise.  While the paper merely states that

“modifications to fishing behaviors such as changing locations and using electric reels are likely to reduce depredation,”

I would argue that the best way to minimize shark depredation is to get a hooked fish up to the boat as quickly as possible, and either land it or release it in the shortest practicable time.

That is not a new or nor a controversial opinion.  Hemingway had already figured it out nearly 100 years ago.

“We try to fight them fast but never rough.  The secret is for the angler never to rest.  Any time he rests, the fish is resting.  That gives the fish a chance to get strong again…You don’t have to kill a horse to break him.  You have to convince him…”

Dr. Andrew J. Danylchuk, another of the paper’s authors, once wrote something similar, with respect to avoiding shark depredation of tarpon in the Florida Keys.

“The longer an angler fought a tarpon on the line, the greater the chances for depredation…

“There is a quick solution…Fight tarpon harder, and get ‘em landed and released in under 10 minutes.  Of course, a shark could still go after it once released, but at least the fish has a fighting chance of survival.”

It’s only common sense.  The less time a fish is struggling in the water, the less time there is for its struggles to attract a shark, and even if they do, the less time the shark will have to locate and depredate the fish.

But a lot of current angling trends work counter to those truths.

There has been a trend over the years to use spinning tackle to catch larger fish, including tuna, sailfish, and larger reef fish such as amberjack and big groupers.  While anglers might find such gear more enjoyable to use, from an ergonomic standpoint, it is far less efficient than the traditional, conventional rod and reel, either paired with a belt and stand-up harness or, when the fish are particularly large, a bucket harness, footrest, and fighting chair, either of which allow the angler to bring the full force of their shoulders, back, and legs into the fight.  A spinning rod, on the other hand, doesn’t take full advantage of all of an angler’s muscle, and so adds extra time—with tuna, sometimes an hour or more—to the battle, time which makes depredation all the more likely.

In recent years, we have also seen trends like slow-pitch jigging, which employ rods that lack any meaningful backbone, and are largely useless for pumping a big fish up from the bottom; instead, the angler just slowly cranks the reel until the fish finally gives up the ghost, again extending fighting times.  Another relatively recent trend, deep-dropping, sees anglers lower baits to the bottom in 800, 900, or even in more than 1,000 feet of water, giving cruising sharks more than enough time to intercept hooked fish somewhere between the bottom and the boat.

Yet anglers blame the sharks for depredation, rather than blaming themselves for setting up what amounts to an all-you-can-eat shark buffet.

Thus, while the new paper provides valuable insights into why and how shark depredation occurs, preventing depredation remains a challenge.  Science can only go so far in addressing that challenge; anglers must be willing to do their part as well.