FISHERIES: MANAGING FOR ABUNDANCE

One of the most confounding concepts in saltwater fisheries management is that of “abundance.”

Intuitively, having a lot of fish around that we can encounter, catch and perhaps take home seems like a very good thing.  

In fresh water, restoring an abundance of native trout, of wild salmon, or of fish such as lake sturgeon is seen as a worthwhile goal.  Pushing out into other fields of wildlife management, you seldom, if ever, hear hunters complain that wildlife managers are trying to increase the abundance of hoofed or feathered game.  In fact, organizations such as the Rocky Mountain Elk Foundation, Ducks Unlimited and Pheasants Forever exist to help managers create and sustain just such abundance.

Most saltwater fishermen aren’t much different from their freshwater counterparts, from duck hunters or from those who pursue grouse or big game, in that they celebrate days when their quarry is plentiful.  The Theodore Roosevelt Conservation Partnership’s 2014 report, A Vision for Managing America’s Saltwater Recreational Fisheries, captured the views of most saltwater anglers when it stated that

“Currently, federal fisheries managers set catch limits for recreational and commercial fishing at or near maximum sustainable yield.  While this may be an ideal management strategy for commercial fishing, where harvesting the maximum biomass is desired, it is not an effective management tool for saltwater recreational fishing.  Recreational anglers are more focused on abundance and size, structure of the fisheries, and opportunities to get out on the water.”

Such comments are supported by a National Marine Fisheries Service survey of recreational anglers, which sought to discover what America’s saltwater anglers valued about their fishing trips.  Anglers were provided with a number of trip characteristics, and asked to rate them on a scale that ranged from “extremely important” to “not important at all.”  It turned out that “fishing with family and friends,” was rated either “extremely important” or “somewhat important” by 87% of all respondents, suggesting that the social aspects of fishing are more important to most anglers than the fish themselves.

But that doesn’t mean that the fish aren’t important.  

“Catching fish” scored a solid second in the list of angler priorities, with 83% of all respondents saying that it was either “extremely important” or “somewhat important” to them.  Surprisingly, the things that non-anglers might think are important to recreational fishermen—taking home as many fish as possible, catching and releasing as many fish as possible, or catching a trophy fish—appeared relatively unimportant to anglers, with each receiving either “extremely important” or “somewhat important” ratings from about 40% of the anglers who answered the survey.  Catching and keeping a limit of any particular species of fish was even less meaningful to most anglers; only about 30% considered doing so either “extremely” or “somewhat” important.

Respondents’ thoughts about fishery management objectives reflected their priorities.  An overwhelming majority—fully 97%--believed that managers should “ensure that future generations will have high quality fishing opportunities.”  

Trailing that, but still important to anglers, were the objectives that “managers should ensure that many types of fish are available to catch,” which received 86% support, and the objective that “large quantities of fish should be available to be caught,” which was supported 82% of all respondents.

Such survey results suggest that anglers want to see fish abundant enough that they have a reasonably likelihood of catching something when they go out for a day with family or friends.  However, neither full coolers, non-stop catch-and-release action, nor very large fish are necessary to make an outing worthwhile. 

The results also suggest that anglers would like to see fish abundant enough to provide for healthy and sustainable fish stocks throughout the foreseeable future—which of necessity includes a robust and resilient spawning stock that can weather changes in their environment—so as to ensure that there will be plenty of fish available to generations of anglers who are yet to be born.

From such results, it is clear that having an abundance of fish in the water is important to most anglers.

However, there is also a minority view.

Some members of the angling community see calls for abundance as a sort of sinister plot, put together by members of the environmental community who, at least in some paranoid fantasies, are seeking to push anglers off the water by increasing restrictions on the recreational catch.  That sort of imagined threat has led to a lot of ill-considered opposition to the concept of abundance, particularly by people who are connected in some way to the recreational fishing industry, and see managing for greater abundance as a potential threat to their livelihoods.

But that opposition comes from a basic misunderstanding of the abundance concept, something that becomes very obvious when one reads comments made in response to one of my more recent blogs.

For the truth is that managing for abundance is good for everyone—for anglers, for angling businesses and, most importantly, for the fish.

To understand what managing for abundance does and does not mean, it helps to go back to the quote from the TRCP’s visioning report that appears near the top of this page, and note that it talks about fisheries managed for “maximum sustainable yield.”  That term isn't actually defined in the Magnuson-Stevens Fishery Conservation and Management Act, although it appears in that law a number of times.  However, “maximum sustainable yield” is generally understood to be

“the maximum level at which a natural resource can be routinely exploited without long-term depletion.”

Magnuson-Stevens provides that

“The terms ‘overfishing” and ‘overfished’ mean a rate or level of fishing mortality that jeopardizes the capacity of a fishery to produce the maximum sustainable yield on a continuing basis.”

And “fishing mortality rate” is defined as

“A measure of the intensity at which a stock is being exploited.  This is the fraction of the fish population (or other defined group) that is expected to be caught at any single point in time.  [emphasis added]”

Reading those three definitions together makes it clear where people go wrong when they argue that managing for abundance is bad for anglers and angler-related businesses, and claim that such management results in reduced recreational landings, for in fact, just the opposite is true.

Managing for abundance leads to larger harvests.

When you take even a minute or two to think about it, the reason becomes very clear:  Since overfishing is defined by a fishing mortality rate that is unsustainable—that is, a rate that will lead to depletion if continued on a long-term basis—and since such fishing mortality rate represents the fraction of a fish population that is removed by fishing activities, an abundant stock of fish will necessarily allow more removals, and so yield a bigger harvest, than a smaller population of the same species will.

To reduce that concept to numbers, if a species of fish can tolerate having no more than 25% of its population removed by fishing in any given year—removing any more fish than that would lead to eventual depletion and thus constitute overfishing—and the biomass of that population was 50 million pounds, fishermen would be able to harvest 25% of that, or 12.5 million pounds.  But if fish became less abundant, and the population shrunk to just 10 million pounds, fishermen would only be able to harvest 2.5 million pounds—far less in absolute numbers, but still 25% of the population.

So abundance clearly leads to larger overall harvests.

But the phrase “overall harvest” is the key to why some people still get confused, and believe that abundance is bad.

 

The fact that a fish stock is abundant doesn’t mean that an individual angler, on any given trip, will be permitted to land land large quantities of fish.  In fact, the opposite often happens—as fish grow more abundant, regulations tighten.

That’s because anglers like to target abundant fish species.

Remember the NMFS angler survey which, not surprisingly, found that catching fish was very important to anglers—much more important than limiting out, taking a lot of fish, or even catching a “big one?”  Fish become much easier to catch when they become more abundant.  So in many rebuilding fisheries—most notably red snapper in the Gulf of Mexico and black sea bass in the Mid-Atlantic region—we see anglers growing frustrated and angry because they are fishing under very restrictive regulations when fish have obviously become far more abundant than they had been before.

What they’re missing is the fact that fishermen, attracted by the increasing abundance of fish, have become far more abundant, too.  Because there are more anglers directing their effort on the species in question, and because more abundant fish are allowing them to be far more successful than they were in the past, the overall recreational harvest still approaches, and often exceeds, the fishing mortality rate that defines overfishing, despite the toughened rules and higher annual catch limits.

And it is the overall fishing mortality rate that determines the health of the stock, even if each individual angler, on each individual trip, is keeping very few fish.

NMFS recreational effort data makes it clear that anglers tend to fish more when fish are abundant, and also tend to pursue the more abundant species. 

For example, in 2000, when weakfish were reasonably abundant, East Coast anglers made more than 1,900,000 trips in pursuit of the species; ten years later, after the population crashed, the number of trips dropped to a little over 100,000. 

On the other hand, black sea bass were fairly scarce off New England in 2000, when northeastern anglers made only 31,000 trips targeting that species; by 2010, as the stock rebuilt and warmer waters shifted fish abundance northward, New England’s recreational fishermen made 190,000 directed sea bass trips.  New England’s black sea bass population continued to grow more abundant, while the abundance of other species, such as cod, striped bass and summer flounder declined.  As a result, by 2018, the number of directed black sea bass trips made off New England had spiked beyond 460,000.

Clearly, in the case of black sea bass, abundance drove effort, which increased even though, during the years 2000-2018, black sea bass regulations grew steadily more restrictive.

Probably no fish demonstrates the effects of abundance more clearly than the striped bass, a species that anglers seek primarily for sport, and only secondarily as food.  Southwick Associates, an economic consulting firm, recently produced a report titled “The Economic Contributions of Recreational and Commercial Striped Bass Fishing,” which clearly shows the steadily decreasing number of recreational striped bass trips taken in each year between 2009 and 2016, which decline corresponds to a similar decline in striped bass abundance, and so illustrates why a decline in fish abundance is bad news for fishing-related businesses.

Striped bass also illustrate the final point—that managing for abundance benefits the long-term health and sustainability of fish stocks.

The Atlantic States Marine Fisheries Commission’s current striped bass management plan includes, as its goal,

“To perpetuate, through cooperative interstate fishery management, migratory stocks of striped bass; to allow commercial and recreational fisheries consistent with the long-term maintenance of a broad age structure, a self-sustaining spawning stock, and also to provide for the restoration and maintenance of their essential habitat.  [emphasis added]”

To achieve that goal, the plan sets several objectives, including

“Manage fishing mortality to maintain an age structure that provides adequate spawning potential to sustain long-term abundance of striped bass populations.”

To achieve its goal, ASMFC’s striped bass management plan sets a target fishing mortality rate that is well below the rate that would produce maximum sustainable yield.  Fishing at maximum sustainable yield generally results in a population that is composed mostly of smaller, younger fish.  Such a population, largely devoid of older, larger females, is particularly susceptible to recruitment failure, for if most fish are removed from the population shortly after they mature, and poor recruitment results in few new fish entering the spawning stock to replace those that have been removed by fishing, the likelihood of the stock collapsing becomes very high.

By managing striped bass for long-term abundance, the fishing mortality rate will be held low enough to permit the age structure of the spawning stock to expand, and include some of the larger, older and most fecund fish, that serve as a buffer against consecutive years of poor recruitment that see few younger fish enter the adult population.

That's a particularly important consideration for striped bass, which tend to see wide swings in annual recruitment success.

More generally, an abundant fish population is more resilient and better able to adapt to environmental changes, a quality that is particularly important given the ongoing climate change that is causing waters to warm along all coasts of the United States.  As noted in the paper “Fisheries regulatory regimes and resilience to climate change,”

“Increased population abundance, age structure, and genetic diversity buffer against stock collapse from environmental shocks.”

Thus, managing fish for abundance just makes sense.

It ultimately leads to increased recreational opportunity, increased levels of sustainable landings, and healthier and more resilient fish stocks.

Despite what some people are saying, it has no downside at all.