DOLPHIN: AN UNEXPECTED ISSUE

 Whether you call them “dolphin,” “dorado,” or “mahi,” the fish that scientists know as Coryphaena hippurus is a remarkable animal.  Widespread throughout the world’s tropical, subtropical, and even temperate seas, the dolphin has a life history that would seem to make it the perfect forage for everything from larger dolphin to people.

They are the piscine embodiment of the saying, “Live fast, die young, and leave a beautiful corpse.”

Dolphin can reach a maximum length of around six feet, and a maximum weight of around 100 pounds, and they do it quickly.  Females are sexually mature when four or five months old, and just 8 inches long, and can spawn two or three times each year.  Larger females can produce as many as 1 million eggs each time they spawn, although smaller individuals’ is less than 10 percent of that.  Such rapid reproduction may be necessary, as the fish live short lives; most survive for less than four years, although an exceptionally old dolphin may live for five.

Such a life history would appear to make the dolphin resistant to even heavy fishing pressure.

The Florida Museum notes that

“Studies conducted on dolphinfish populations have concluded that it should be able to withstand high levels of harvest.  Life history characteristics, including fast growth rates, high reproductive capability, and low age at maturity, make the dolphinfish resistant to overfishing within the Gulf of Mexico and south Atlantic fishery.”

The Monterey Bay Aquarium’s “Seafood Watch” lists hand-caught dolphin as a “best choice” consumers to purchase, and while it gives lower ratings to dolphin caught on other gears, the lower ratings are associated with such gears’ tendency to kill other, depleted species as bycatch, and not out of any concern for the health of the dolphin stock.  The International Union for the Conservation of Nature essentially concurs, deeming the dolphin a species of “least concern” from a conservation perspective.

Ten years ago, the Coastal Conservation Association, an anglers’ rights group that draws most of its membership from states in the southeastern U.S., went farther, and actively opposed the South Atlantic Fishery Management Council’s efforts to establish annual catch limits for dolphin and other regional species.  It went so far as to send an “action alert” to members, in which it stated that

“For unassessed species, unless there is clear evidence that the stock is declining, the control rule should not limit current harvest.  It is absurd to employ an [acceptable biological catch] control rule that would require more than a 50 percent reduction in cobia, and significant reductions in wahoo and dolphin, when no problems have been determined with the stock.”

It now appears that all of those organizations could have been a bit too optimistic about the health of the U.S. East Coast dolphin population, and its ability to sustain high levels of fishing mortality.

There is no stock assessment available for the dolphin population that inhabits the ocean off the U.S. East Coast, so it is impossible to know whether dolphin are overfished, experiencing overfishing, or both.  However, there have been a multitude of observations made off the east coast of Florida, by both anglers and charter boat operators, that could be heralding a problem.

A recent article in Florida Sportsman magazine published a handful of those observations.  Robert Malloy of Coral Springs, Florida said

“I have noticed significant reductions in quantity and size of dolphinfish in the last 5 years and I believe there should be changes made to size and [bag] limits.”

Ryan Buell of Palm City noted that

“I see a huge decline of big fish in the area.  There are so many people on social media these days posting (60) 18” fish and they think this is cool and no one is doing anything to stop this,”

while Robert Pustizzi of Plantation reported

“I’ve been fishing out of Port Everglades since 1980.  Many of us have noticed a sharp decline in the size of dolphin being caught from Hallendale to Lake Worth.  Large dolphin are becoming very hard to come by and 2020 was probably the worst year I’ve seen.”

The South Atlantic Fishery Management Council decided to address the issue, but quickly ran into a problem.  While anglers and charter boat operators operating out of southeast Florida and the Florida Keys demanded that the 10 fish per person/60 fish per boat bag limit be slashed—the most-heard suggestion was to reduce it to 5 fish per person and no more than 30 per boat—that suggestion ran up against strong opposition from the North Carolina charter boat community, which wasn’t ready to admit that a problem existed.

Data from the Marine Recreational Information Program is somewhat ambiguous.  While it showed that dolphin landings in the South Atlantic region hit a ten-year low in 2020, when an estimated 839,000 fish were harvested by anglers, previous years were very much in line with the ten-year trend.  In fact, aggregate landings for 2017-2019 were somewhat higher than the aggregate landings for 2011-2013, and 2018 saw the second-highest annual landings of the last decade.

But data from the State of Florida showed a slightly different trend.  2019 and 2020 landings were the lowest for the period 2011-2020, and represented the final two years of a marked decline that began in 2015.  North Carolina landings, on the other hand, have varied from year to year but, although they hit a 10-year low in 2020, seemed to show no similar pattern.

The most discernable difference between Florida and North Carolina’s dolphin landings is in the proportion of large dolphin in the landings.  While Florida accounts for most of the dolphin landings, its fish tend to trend small; if the minimum length of a “large” dolphin is arbitrarily set at 36 inches fork length, then between 2011 and 2020, such large fish made up between 1.98% (in 2017) and 14.57% (in 2016) of all Florida dolphin landed, compared to a range of 6.80% to 18.81% for the South Atlantic region as a whole.  Over the past five years, the percentage of large dolphin in the Florida catch saw wide swings, going from 14.57% all the way down to 1.98% the next year, then back up to 4.22%, then 6.22%, and finally 7.16% in 2020.

Over all, the percentage of large fish in the stock between 2016 and 2020 was generally lower than it was between 2011 and 2016.

North Carolina data showed a very different trend.  Large dolphin made up between 8.31% (in 2014) and 32.70% (in 2016) of overall landings, with the percentage of large fish generally increasing in more recent years.  Taking 2016, when North Carolina, Florida, and the South Atlantic region all registered their highest percentage of large dolphin for any time in the last decade, out of the discussion, North Carolina saw its large fish percentage go from a range of 8.31% to 12.22% for the years 2011-2015, to a range of 11.81% to 18.42% for the years 2017-2020, with 2020 seeing large dolphin making up 17.28% of landings.

That put the South Atlantic Council in a difficult position.  As described in a Council release,

“The proposed reduction in the daily trip limit [that saw the boat limit go from 60 dolphin to 54] was reached after much discussion by the Council in an effort to address concerns expressed by fishermen, primarily from South Florida and the Florida Keys, about declines in the number and size of Dolphin landed in recent years.  In contrast, many fishermen involved in the for-hire fishery off the coastd of North Carolina opposed reductions to the current 60-fish vessel limit, citing negative economic impacts to the charter fishery and noting limited changes to the number and sizes of Dolphin fish observed in their area over the past few years.”

Now, members of the Florida fishing community, who believe that the reduction in the boat limit was too trivial to restore their dolphin fishery, are continuing their call for more restrictive regulations, and are receiving some support from the conservation community.  Two related organizations, the Beyond Our Shores Foundation and the Dolphinfish Research Program, argue that research has shown that dolphin on the East Coast and Gulf of Mexico have demonstrated connectivity, and should all be governed by a set of more conservative regulations, which should include a 30-fish boat limit and 20-inch minimum size.

Florida Sportsman magazine has launched a petition urging the South Atlantic Council to adopt the same 30-fish limit for recreational vessels, and to establish a new 2,000-pound trip limit for commercial boats.

Good arguments could be made for both proposals.

But in making those arguments, we should never forget that the foundation of good arguments, and good fishery management, is good science, and in the case of dolphin, that is sadly lacking.

As mentioned earlier, there is no stock assessment.  Biologists have generally assumed that, because of their life history, dolphin can sustain high levels of fishing mortality, but no one knows that for certain, just as no one knows that status of the dolphin population in the northwestern Atlantic.

There is some data, developed by organizations such as the Dolphinfish Research Program, which casts some light on that dolphin population. 

The data shows that dolphin are travelers.  A satellite tag recorded one fish traveling 152 miles in the course of a single day, although more typical travel speeds range between 10.4 and 44.9 miles per day.  In the northwest Atlantic, such travel generally takes on a clockwise path, with dolphin tagged off the east coast of Florida moving north along the coast, sometimes as far as Massachusetts, before moving offshore and returning south, perhaps circumnavigating the Sargasso Sea along the way.  Individual fish have traveled as much as 2,500 miles between the place where they were tagged and the place of recapture.

At the same time, about three-quarters of the dolphin tagged off eastern Florida are recaptured in Florida waters.  Some fish tagged off southern Florida and the Keys are recaptured in the same area three or more months later, while some dolphin tagged off eastern Florida move south instead of north, and have been recaptured as far away as Key West. 

Such recaptures might suggest that Florida anglers are fishing on two different bodies of fish, one being the larger, migratory population, one being a smaller, more localized body of fish. 

If, and I emphasize if, that is the case, it is possible that the larger population that migrates along the coast remains relatively healthy, while a smaller local Florida population is experiencing more intense fishing pressure, both off Florida and off the Bahamas, and is in need of more restrictive management measures.

Such second, localized stock might explain why landings and size data from Florida show noticeable declines, while data from North Carolina, and from the region as a whole, do not.

But at this point, that’s all speculation and nothing more, because it lacks scientific support.

At the same time, the apparent decline in the size and numbers of dolphin off Florida should already be teaching one lesson:  That no matter how abundant a particular species of fish may seem to be, and how resistant it may appear to be to overfishing, in the absence of data, precautionary management is always required.

Because when regulations can be little more than a shot in the darik, it is all too easy for managers to shoot themselves in the foot if they become too optimistic.