Longline Fishing (How What You Don’t Know Can Hurt You)
This article provides a general overview of the subject of longline fishing, including a detailed breakdown of how the practice came to prominence, how it is done, the kind of environmental damage it causes, and what might be done to mitigate or stop that damage. The author compiles global statistics to present a thorough picture of how longline fishing affects many different species (from birds to aquatic mammals), and shows possible solutions in an objective and practical manner.
Author Kevin Fitzgerald succinctly sums up the factors that have given rise to the practice of longline fishing in his article. First and foremost, he states that, “commercial fishing enterprises are bound by 3 realities; the actual operational costs of fishing […], the supply of the target species, and the demand for and price of the target fish set by a world market.” Soon afterwards, he states that, “of all the tens of thousands of species of fish in the oceans, world demand clamors for only 5 fish: cod, tuna, halibut, salmon, and sea bass (and before that the now somewhat protected swordfish).” This context, he explains, sets the tone for the now-widespread practice of longline fishing, a method of fishing that may meet some measure of efficiency in terms of operational costs, but wreaks havoc on oceans because of its indiscriminate, “nonselective” nature. “Worldwide,” Fitzgerald notes, “a recent estimate of the total marine bycatch discarded was more than 30 million tons per year, or about one-third of the yearly total catch.”
What kind of animals are dragged down in the bycatch? Fitzgerald notes that in particular, albatross, sea turtles, and marine mammals suffer the effects of longlining, as well as sharks and other non-target species. The reasons for each of these species being caught by longlines varies: for example albatross are attracted to the bait found at the end of one of the approximately 10 billion hooks that are laid out each year; and sea turtles can find themselves tangled up in stray lines, the victims of “ghost fishing.” Fitzgerald notes a range of possible solutions to these longlining problems, such as using bird-scaring bait or lines, weighting the lines differently to make them float at different levels in the ocean, dyeing the bait to be less appealing to bycatch species and so on.
Overall, the picture presented here is rather bleak, but not irredeemable. Fitzgerald notes that, “not only is it incredibly damaging to nontarget species and oceanic ecosystems, but also a nearly more insidious aspect of this practice is that the majority of the public are completely unaware of its existence.” He settles on raising public awareness about the problem (and potential solutions) as a key way to bring about change, but since his work is published in a journal for veterinarians, he urges his colleagues to become informed about the issue, and states emphatically that “wherever there is animal suffering or wanton waste of life, veterinarians should stand up and speak up.”
Original Abstract:
Longline fishing utilizes monofilament lines that can be as much as 62 miles long. The line itself is buoyed by Styrofoam or plastic floats. Usually, at about every 100 ft, a secondary line is attached and hangs down from the mainline. The lines are baited with mackerel, squid, or shark meat and have as many as 10,000 hooks. Every 12-24 hours, the line is hauled in, mechanically rebaited, and set back into the water behind the vessel. The baited hooks can be seen by albatross and other seabirds as they are placed in the water or being hauled out. When the birds dive for the bait, they are hooked, dragged behind the fishing boat, and drown. Spectacularly nonselective, longline fishing techniques also hook many other forms of marine life—“bycatch” (sea turtles, seals, dolphins, penguins, sharks, and many other nontarget finfish). It is estimated that 300,000 seabirds (including 100,000 albatross) die on longlines each year. Albatross are among the longest-lived birds. They can live up to 60 years and some species do not start breeding until they are 10 years old. They have a low reproductive rate and many species only breed every other year. In addition, a species like the Wandering Albatross (Diomedea exulans) rears its chicks for an average of more than 270 days. Albatross pair for life and may take years to find a new partner if their mate is killed. Owing to their incredibly low reproductive rate, albatross are particularly vulnerable to longline fishing. Currently, it is believed that 4 albatross drown per 100,000 hooks set. This is more than 400 birds a week. The current mortality rate for adult birds is not sustainable and for some species, the birds are dying faster that they can repopulate. Currently, 19 of the world’s 22 albatross species are threatened with extinction. This year longline fishing ships will set 10 billion hooks worldwide. Various mitigation measures (bird-scaring lines, weighted, faster-sinking line, setting lines deeper out of the bird’s sight, reduction in the amount of offal discarded from fishing boats, night fishing, and restriction of longline operations from areas where nesting and foraging birds are congregated during the breeding season, among others) have been proposed and attempted. There is no one panacea for the effects of longlining and mitigation efforts are most successful when used in combination. Some of these mitigation measures have shown very promising results. Some experts feel that government legislation, regulation, and enforcement in conjunction with incentives for the fishing industry to incorporate and implement mitigating techniques have the best chance in ameliorating the problem. The public is surprisingly unaware of this wanton and wasteful exploitation of the ocean’s resources, and the worldwide demand for seafood continues to rise. Meanwhile, globally, fishermen voice the same complaints: fewer fish, smaller fish, shorter fishing seasons, bizarre developments in their seasonal appearance and dispersal, and fewer overall species seen. These are all the classic signs of overfishing. Each year it is estimated that some 90 million tons of wild fish are harvested from our planet’s oceans. Nearly 30 million tons of this is discarded as the incidental bycatch of nontarget species. If international curbs are not placed upon wasteful fishing practices, we are doomed to learn a painful maxim. “The ocean is not infinite.” Veterinarians must become involved in worldwide conservation efforts, acting locally, while thinking globally.