by Hemingway himself argued for shark deterrence while trying to land a bluefin tuna in Bimini, Bahamas. Kip Farrington, longtime editor of Field & Stream magazine and Hemingway’s confidante, noted that “none of these magnificent fish was ever boated near Bimini without a shark tag.” Today, anglers often refer to sharks as “the taxman”.
People preying on sharks
Sharks have been harvested commercially in the Gulf since the 1930s. Catches increased during World War II, in part because shark livers were used in the production of Vitamin A, and decreased after 1950 with the development of synthetic vitamins.
Shark catches boomed again in the 1980s, encouraged by federal regulators, who saw sharks as an “underutilized resource.” But within a decade, scientists determined that several stocks of Gulf sharks, including sandbars and dusky sharks, were overfished.
In 1993, NOAA issued the first federal fisheries management plan for sharks in US waters in the Atlantic Ocean, including the Gulf of Mexico. These regulations created a path to rebuilding stocks by requiring permits and establishing recreational trip limits and commercial catch quotas.
Today, many of the Gulf’s overfished shark stocks are recovering. As evidence mounts that sharks are an important part of healthy oceans, this is a conservation success story. However, many anglers blame increases on disregard for regulations enacted to rebuild shark populations.
Transfer baselines
Experts agree that there are more sharks in the Gulf of Mexico today than there were 30 years ago. But how do these populations compare to pre-1989 levels, when commercial shark fishing boomed?
Over time, this question becomes more difficult to answer as people gradually accept environmental degradation. Marine biologist Daniel Pauly calls this habit “shifting baseline syndrome”. When it comes to fisheries, each new generation of fishermen takes the current, often reduced, status of fish populations as a baseline and forgets that there was a time when these species were much more abundant.
In this case, modern anglers are comparing the increase in shark numbers in the Gulf of Mexico over the past 30 years – a time when many shark populations were overfished.
Raised baselines
The recovery of once overfished populations can create the opposite, known as rising baselines, with population increases as a result of conservation and management efforts.
When populations are overfished and then rebuilt, they can create a sense of overcrowding. When the recovering species becomes a predator, it can lead to human-wildlife conflict.
For example, recovering populations of California sea lions are now competing with fishermen for their catch along the Pacific coast. Off Cape Cod, Massachusetts, the same thing happens with gray and harbor seals. The seals, in turn, are attracting white sharks.
The call to destruction
Sportfishing is a popular and profitable year-round industry throughout the Gulf of Mexico. As reports of depredations increase, so do calls to cull shark populations.
Similar action has been proposed elsewhere for other marine predators, including sea lions in California and goliath groupers in Florida.
However, studies show that predator removal is rarely an effective strategy. It is particularly ineffective for species such as sharks that move around a lot and will easily recolonize areas that have been killed. Predator killers also pit people with different values, such as fishing boat operators and conservationists, against each other.
To pay the tax man
Unfortunately, there is no silver bullet solution to deterring sharks. The Gulf’s sport fishing industry has grown, and sharks likely learn to associate boats with an easy meal.
Shark barriers are available, and new versions are continually being developed. Some fishermen are changing their practices to avoid sharks – for example, changing locations frequently and not anchoring or fishing further offshore to avoid coastal species such as bull sharks.
NOAA-funded research identified sand sharks and bull sharks as the species most frequently preyed upon by capture. The agency is analyzing ways to better measure declines and assess stocks of these two species to understand their population trends.
In my opinion, measures like these, along with better data on which sharks are taxing fishermen and where, are the most promising ways to help anglers live with sharks in the Gulf.
This article is republished from The Conversation, a non-profit, independent news organization that brings you facts and analysis to help you make sense of our complex world.
It was written by: James Marcus Drymon, Mississippi State University.
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James Marcus Drymon has received funding from NOAA Fisheries and the Gulf States Marine Fisheries Commission to study depredation.
