WILL MENHADEN MANAGEMENT REFORM COME TO THE GULF OF MEXICO?

 

On February 28, the National Marine Fisheries Service announced that its scientists had developed “A Pathway Toward Ecosystem-Based Management for Gulf Menhaden.”

The announcement heralded the publication of a new study, performed by NMFS' Southeast Fisheries Science Center.  The paper, “Identifying trade-offs and reference points in support of ecosystem approaches to managing Gulf of Mexico menhaden,” appeared in the January 6, 2023 edition of the journal, Frontiers in Marine Science.

In announcing the study, NMFS noted that it will be used

“to evaluate how changes in menhaden fishing pressure may effect the entire ecosystem.  Gulf menhaden have the largest fishery yield in the Gulf of Mexico and support the second largest fishery by weight in the United States.  Their presence in the Gulf if crucial.  Fisheries management is becoming increasingly aware of this species’ importance, particularly after the successful implementation of an ecosystem approach for Atlantic menhaden.  There is also growing interest in the management of the stock given the commercial fleet’s Marine Stewardship Council certification and increasing interest from stakeholders across the Gulf states.”

The NMFS release refers to the Atlantic States Marine Fisheries Commission’s decision to move forward with ecosystem reference points for Atlantic menhaden in 2017, the and development of a benchmark stock assessment which considered such reference points in 2020; a stock assessment update, utilizing ecosystem reference points, released in 2022, found the Atlantic menhaden stock to be healthy, and the fishery to be achieving the fishing mortality and fecundity targets.

Given the importance of Gulf menhaden as a forage fish, it isn’t surprising that a similar effort to develop ecosystem reference points has emerged in the Gulf of Mexico.

In some ways, the new study is similar to the work that was done to develop ecosystem reference points for Atlantic menhaden, but it also differs in important ways.  On the East Coast, biologists had been working on multi-species population models, which included Atlantic menhaden, since the early 2000s.  In the Gulf, the recently-released study was the first of its kind.

In addition, the ecosystem reference points for Atlantic menhaden focus on the needs of the striped bass, which is both a major predator and the focus of what is arguably the coast’s primary recreational fishery.  In the Gulf, no single species has a similar status, and the ecosystem reference points were thus required to examine the needs of multiple fishes. 

The Gulf study also takes a more detailed look at the impacts of bycatch in the menhaden purse seine fishery, using data from studies of purse seiners’ catch that do not exist in the Atlantic fishery.  As the study notes,

“A considerable portion of the impact of the menhaden purse-seine fishery on predatory species occurs through bycatch…

“While bycatch has historically been considered negligible compared to menhaden landings, estimated at approximately 2.35% of total fleet landings by weight, this percentage can equate to a substantial amount of bycatch…Our trade-off analysis revealed depletion of some groups attributed to increased mortality through bycatch of the purse seine menhaden fleet…  [references omitted]”

Thus, bycatch impacts attributable to industrial-level menhaden harvest are an important aspect of the ecological reference point issue.

So what, exactly, did the study reveal?

It turns out that yes, there seems to be a connection between menhaden abundance, and menhaden fishing mortality, and the abundance of predators, but the extent of that connection differs from species to species.  In some cases, it even appears that increased menhaden fishing mortality can lead to an increase in some species abundance; such counterintuitive result seems to occur because some species of fish, such as yellowfin tuna, feed heavily on squid other animals that benefit when menhaden populations are lower and thus lessen competitive pressures.

Of all the affected fishes, the various sea trout (species belonging to the genus Cynoscion, including the recreationally important “speckled trout,” Cynoscion nebulosus) probably suffer the greatest harm from the menhaden purse seine fishery; the study suggests that about 29% of their overall fishing mortality can be attributed to purse seine bycatch.  In addition, sea trout suffer from purse seiners removing menhaden from the ecosystem.  The study found

“For most groups, [biomass in 2016, the last year of the study’s time series] is higher than Btarget (B at 75% Fmsy), indicating a sustainable state of the fishery that can tolerate higher F rates.  However, for sea trout, [biomass in 2016] is lower than the B_target, indicating an unsustainable state for this group and that target biomass can be achieved by adjusting sea trout and menhaden F.  Under current sea trout F, menhaden fishing would have to be reduced to near 0 to achieve B_target, whereas if sea trout were fished at their own F_target (0.134), then menhaden F would need to be reduced to 18.9% of current rates.”

Sea trout seem somewhat unique, in that they are significantly impacted by both menhaden removals and purse seine bycatch.  In the case of many other species, only one aspect of the menhaden fishery causes most of the harm.  King and Spanish mackerel were primarily affected by a reduction in menhaden numbers; blacktip sharks, red drum, and some tuna (not including yellowfin) also were negatively impacted by increases in menhaden fishing mortality.

Purse seine bycatch had the greatest impact on “coastal piscivores” such as tarpon, ladyfish, and snook, along with large and small coastal sharks, various croakers and drum, and “oceanic piscivores” such as cutlassfish.

The good news is that the study found menhaden fishing mortality to have declined in recent years.  Between 1977 and 2007, menhaden fishing mortality would have exceeded the ecosystem-based fishing mortality target proposed by the study in all but one year; for approximately two decades between the mid-1980s and early 2000s, the ecosystem-based fishing mortality threshold would have been exceeded as well.  However, between 2008 and 2016, the last year considered in the study, the target was exceeded in only five of such years, and the threshold in only three.

While that still leaves plenty of room for improvement, it still suggests that things are getting somewhat better.

Will ecosystem reference points for menhaden ever be adopted in the Gulf, as they were on the Atlantic coast?  Perhaps, but it won't be an easy thing to accomplish.

The Gulf Menhaden Fisheries Coalition issued a statement in response to the NMFS’ release, which started out,

“The Gulf of Mexico menhaden fishing industry supports the development and implementation of Ecosystem Based Management (EBFM).  We fully recognize the importance of managing marine resources on an ecosystem basis, as all species within the Gulf of Mexico interact with one another to a varying extent…”

That’s a fine beginning but, as is so often the case, the Devil lies in the details, and the details, as set out by the Menhaden Coalition, are certainly devilish enough:

“While there is broad support for EBFM, one of the current challenges in adopting this new system is accurately accounting for the complex interactions between predator and prey species.  This includes everything from phytoplankton at the base of the food chain, to apex predators like sharks at the top of the pyramid of trophic relationships…  [emphasis added]”

In other words, the industrial menhaden fishery claims to be more than willing to accept ecosystem based management, so long as such management takes into account every organism in the ecosystem.

And from a practical standpoint, that’s an impossible task.  No one has enough time or money to get that job done.

So anyone arguing for ecosystem-based management ought to know that the industry plans to stand in their way.

Still, the biggest obstacle to reforming Gulf menhaden management isn’t the purse seine fleet; instead, it’s the fact that there is no management structure in place in the Gulf that has the legal authority to get the job done.

The study was conducted under the aegis of NMFS, and federal regulators, acting in concert with the Gulf of Mexico Fishery Management Council, could certainly put a Gulf Menhaden Fishery Management Plan in place, if the Council was inclined to do so.  However, such management plan would only hold sway in federal waters (or over federally-licensed vessels), and with state waters extending three miles offshore—nine miles offshore of those Gulf states that derive their jurisdiction from Spanish land grants—there would still be plenty of room for the menhaden fishery, which typically operates realtively close to shore, to fish free from the strictures of federal law.

That wasn’t a problem on the Atlantic coast, where menhaden management is under the purview of the Atlantic States Marine Fisheries Commission.  There, thanks to the Atlantic Coastal Fisheries Cooperative Management Act, the ASMFC has the authority to adopt fishery management plans and then require the coastal states to comply with their provisions.  Once the ASMFC decided to adopt ecosystem reference points for Atlantic menhaden, all states had to fall in line, whether the menhaden were caught in state or federal waters, or risk having their menhaden fisheries completely shut down.

But even though a Gulf States Marine Fisheries Commission exists, it has no real authority.  States may come together to discuss fisheries matters, perform cooperative research, and even adopt management plans, but the Gulf States Commission cannot compel member states to adopt such plans’ provisions.  Instead, states are free to regulate their own menhaden fisheries in any way that they choose.

Until that situation changes, the chances for meaningful menhaden management reform in the Gulf are extremely slim.