FISHERIES MANAGEMENT, AND WHAT FISHERMEN FAIL TO PERCEIVE

 

Fishermen, by their nature, spend a lot of time on the water.  If they fish commercially, or run a for-hire boat, they’re out just about every day that weather and business considerations allow; if they fish recreationally, other factors, such as jobs, spare cash, and family obligations enter the picture.  But whether recreational, commercial, or for-hire, fishermen put in enough time to observe changes in environmental conditions, fish movements, and the health of fish stocks.

Such observations are essential to a fisherman’s success, as they provide a matrix of information that reveals where fish will most likely be at a particular juncture of season, water temperature, wind, and tide.  They also inform a fisherman’s views on the health of fish stocks and the value of particular management measures.  

But in such cases, fishermen can easily be led astray, in part because their observations are usually limited in space and time, and also because of the very human tendency to succumb to confirmation bias, which leads people to remember and give higher value to observations that support their existing beliefs and interests, while discounting those that challenge such preexisting values.

Thus, we often hear for-hire captains in the northeastern striped bass fishery argue that bass are shifting their spawning grounds north, even though there are no scientific data to support such claims, rather than admit that years of extremely poor recruitment in the Chesapeake Bay is going to require managers to adopt more restrictive regulations.  

Similarly, after a stock assessment update found that the bluefish stock had become overfished, we heard members of the recreational fishing industry argue that the population hadn’t actually declined, but merely moved offshore where managers can’t find them, based on a handful of offshore encounters between bluefish and commercial and recreational fishermen (the interesting thing about such comments, from my perspective, is that I fish offshore throughout the summer, spending a substantial amount of time chumming for sharks, and am now encountering far, far fewer bluefish in my offshore chum slicks than I did in the 1980s and 1990s—even than I did in the early 2000s—which would seem to contradict the claim that the bluefish stock is healthy, but merely remaining in deeper waters).  Once again, such comments were offered in the hope of avoiding more restrictive regulations.

Right now, we’re seeing the same phenomenon play out in the gag grouper fishery in the Gulf of Mexico.  Because the State of Florida has been doing quite a bit of research on gag grouper, the current controversy surrounding that fishery illustrates why fishermen’s objections to management measures can be based on misconceptions arising out of incomplete, and perhaps biased, understanding of the relevant facts.

This year, the Gulf of Mexico Fishery Management Council agreed to open the recreational gag grouper season on September 1.  However, that season is already over, as it was only scheduled to run for two weeks, due to problems with the gag grouper stock.

The short season led to many unhappy anglers, with one reportedly saying,

“What a joke this has become,”

while another, probably unaware of the irony in his comment, said,

“What an unfortunate situation we find ourselves in.  Resources being governed on emotion, you know, under the guise of poor science.  It’s a shame.”

A writer for the Bradenton [FL] Herald wrote,

“After studies and quotas and all sorts of angler/government/legal interaction, this is what we’ve been left with.  A short two-week window in the middle of hurricane season when the water is the warmest.  It is almost a slap in the face to anglers.”

Yet the same writer concedes,

“I will admit that gag grouper landings have been more sparse in my recent fishing experiences than years past,”

and that

“Anglers pre-fishing [ahead of the season] have caught legal-sized fish, but they haven’t been in extreme abundance,”

although he tries to explain away his own lower catches by saying,

“much of that is because I actively try to avoid them.”

Another angler quoted in the article complains about the number of undersized fish, or fish caught out of season, which end up being eaten by sharks or Goliath grouper sometime after being hooked and/or released.

But the one group of people that the writer does not quote are the scientists who study gag grouper, the same group of folks who could provide plenty of reason for the short recreational season.  For, contrary to the claims of the angler who said that gag grouper were “governed on emotion…under the guise of poor science,” there are good reasons to engage in precautionary management.

Biologically, gag grouper are what is known as a protogynous hermaphrodite; that is, a fish that begins life as a female, but eventually transitions into a male.  Biologists previously believed that the health of the stock depended upon the number of breeding-aged females, and the last stock assessment, which was reliant on female abundance, found the stock to be neither overfished nor experiencing overfishing.  However, commercial fishermen were having trouble filling their quotas and, as the Bradenton Herald writer noted, anglers weren’t finding overwhelming numbers of adult fish.

Concerned by such signs of declining abundance, Florida scientists decided to take another, deeper look at the resource.  It turned out that males matter more than people once thought.

The most recent stock assessment found that males only make up two to three percent of the overall gag population, as opposed to their historic level of 17 percent.  Such males spend the entire year in deep water, typically at depths of more than 165 feet, on or near the spawning grounds.  Some, but not all, of the spawning areas have been designated as marine protected areas in order to help conserve the gag grouper stock.

Immature females, which typically means fish between one and four years of age, remain in relatively shallow (average of 70 to 75 feet) inshore waters, while mature females form pre-spawning aggregations during the late fall and early winter (November-February) in 50 to 400 feet of water, before joining the males on the spawning grounds.

When a team of researchers examined the gag grouper stock, they discovered that “overall gag grouper abundance is low.”  They also found that the relatively few males that remain in the population are unevenly distributed on the spawning grounds.  About five percent of the fish within the marine protected areas are males, well below the 15 percent that the researchers expected to find in such places; in spawning areas outside the marine protected areas, the researchers found almost no males at all.

In the paper reporting their findings, the researchers

“propose[d] that shallow-water pre-spawning aggregations are a key spatio-temporal bottleneck to gag productivity.  They appear to be an important source of [female to male] transitionals and are heavily fished, which may negatively impact male recruitment to the spawning grounds.”

They also found that current regulations were not sufficiently restrictive to rebuild the proportion of males in the spawning stock to the historical 17 percent.

Thus, the anglers quoted in the Bradenton Herald article had it all backwards.  It was not the fishery managers, but the anglers, who were basing their views on “on emotion…under the guise of poor science.”  They saw—and targeted—the abundance of females, including fish in transition from female to male and, by doing so, drove the level of males below the level needed to maintain a healthy stock.

As the researchers noted,

“the male population in the [Madison Swanson marine protected area] may be aging with limited recent recruitment of younger males rather than indicating a recovering stock, highlighting our need to better assess male recruitment and the processes driving it.  The mating function (relationship between sex ratio and fertilization success) plays an important role in the productivity of protogynous species…but is poorly understood.  Males displayed low milt (sperm) reserves during the spawning season which is a pattern associated with pair spawners.  Because gag are pair spawners and female gag are multiple batch spawners (meaning they produce multiple batches of eggs throughout the spawning season), males would have to spawn with multiple females per day, every day of the [approximately] 78-day spawning season.  Although make spawning frequencies are unknown, given the low milt reserve gag displayed this seems unlikely to be accomplished.

“With the current low observed sex ratios being close to those seen in the 1990s when gag were considered overfished and undergoing overfishing, the above evidence suggests that male abundance is well below what would be expected in a healthy stock.”

Anglers saw a lot of gag, and based on the apparent abundance, assumed that the stock was healthy and the short season unnecessary, but they were completely unaware of the skewed sex composition of the stock, and the implications of the shortage of males on the stock’s long-term sustainability.

They didn’t realize that far from being “a slap in the face,” the two-week season was really a helping hand, both to the gag grouper and to those who plan to be fishing for them a few years from now.

The story of the gag grouper is just one more example of why fishermen’s comments on the health of fish stocks need to be taken with a very large grain of salt.  While fishermen know what they see—or at least think they see—when out on the water, they rarely have a complete picture of all of the factors that bear on the status, and long-term prospects, of a fish stock.

And, as is so true in many facets of life, it’s what one doesn't know that can often cause the most harm.