CONSERVATION

New tech­nol­ogy can mon­i­tor world­wide ef­forts

Marlin - - CONTENTS DEPARTMENTS - BY JASON SCHR AT WIESER, CONSERVATION DI­REC­TOR, IGFA

Have you ever won­dered how much com­mer­cial fish­ing ac­tu­ally takes place on the planet’s oceans?

Un­like agri­cul­ture and forestry, it has been dif­fi­cult, if not im­pos­si­ble, to get a good han­dle on the spa­tial and tem­po­ral foot­print of com­mer­cial fish­ing. And while it’s true some fleets do have ves­sel mon­i­tor­ing, log­books and on­board ob­servers, these data have pre­vi­ously only pro­vided a patch­work glimpse of how com­mer­cial fish­ing op­er­ates on a global level. How­ever, new tech­nol­ogy in the form of the au­to­matic iden­ti­fi­ca­tion sys­tem now al­lows re­searchers to quan­tify the be­hav­ior of global fish­ing fleets, right down to in­di­vid­ual ves­sels.

A re­search study pub­lished in the jour­nal Sci­ence ear­lier this year pro­cessed 22 bil­lion AIS mes­sages and tracked more than 70,000 in­dus­trial fish­ing ves­sels from 2012 to 2016 to de­velop a global foot­print of fish­ing over both time and space. The study’s data set of more than 70,000 ves­sels is just a small por­tion of the 2.9 mil­lion mo­tor­ized fish­ing ves­sels es­ti­mated to be ply­ing Earth’s oceans, but it does con­tain the ma­jor­ity of ac­tive ves­sels larger than 24 me­ters that are man­dated to trans­mit AIS sig­nals.

Dur­ing 2016, the study’s authors cap­tured 40 mil­lion hours of fish­ing ac­tiv­ity by ves­sels that con­sumed an es­ti­mated 19 bil­lion kilo­watts of en­ergy. Col­lec­tively, these ves­sels cov­ered a dis­tance of more than 460 mil­lion kilo­me­ters, which is the equiv­a­lent of 600 trips to the moon and back. How­ever, as you might ex­pect, fish­ing ef­fort is not dis­trib­uted evenly across the planet. Ar­eas such as South Amer­ica and West Africa that ex­pe­ri­ence up­welling were iden­ti­fied as hot spots, as were the north­east At­lantic and north­west Pa­cific. In all, the re­searchers es­ti­mated that 73 per­cent of the world’s oceans were fished in 2016. To put this into per­spec­tive, only 34 per­cent of the planet is uti­lized for agri­cul­ture and graz­ing.

Of all the fish­ing-gear types mon­i­tored

in the study, longlin­ing was the most wide­spread and was ob­served in 45 per­cent of the ocean. Gear types also dif­fered by lat­i­tude. Trawl­ing was most preva­lent at higher lat­i­tudes, purse-sein­ing in trop­i­cal re­gions, and longlin­ing in the mid­dle lat­i­tudes. Long­line ves­sels were also found to have the great­est av­er­age trip length of just over 3,800 nau­ti­cal miles, and dis­played both transoceanic and cir­cum­global move­ments. In­di­vid­ual na­tions were found to fish mostly within their own ex­clu­sive eco­nomic zones, while China, Spain, Tai­wan, Ja­pan and South Korea were re­spon­si­ble for more than 85 per­cent of the fish­ing that took place on the high seas in ar­eas be­yond their na­tional ju­ris­dic­tion.

The study found that fish­ing ef­fort in the mid­lat­i­tudes drops with the an­nual fish­ing mora­to­ria in China, and that there is an­other small drop in the higher lat­i­tudes that cor­re­sponds with the Christ­mas hol­i­day. Sur­pris­ingly, tem­po­ral pat­terns of net pri­mary pro­duc­tiv­ity — the stuff that fu­els the oceans’ ecosys­tems — had less of an ef­fect on fish­ing ef­fort than hol­i­days and po­lit­i­cal clo­sures. Pre­vi­ous stud­ies have doc­u­mented that, on av­er­age, fuel ac­counts for roughly 24 per­cent of fish­ing costs. In­ter­est­ingly, how­ever, the authors found that a 50 per­cent or more drop in fuel price had min­i­mal ef­fect on fish­ing ef­fort. One ex­pla­na­tion for this may be the in­sid­i­ous and preva­lent na­ture of fuel sub­si­dies that de­cou­ple en­ergy costs and fish­ing ef­fort.

Put sim­ply, there is a hell of a lot of com­mer­cial fish­ing that takes place an­nu­ally on our planet’s oceans. And while this study pro­vides key in­sight into what’s go­ing on over time and space, it does not take into ac­count the preva­lence of small-scale and ar­ti­sanal fish­eries that oc­cur close to shore. One fi­nal piece to con­sider is even though com­mer­cial fish­ing has a larger global foot­print than any other form of food pro­duc­tion, it ac­counts for just 1.2 per­cent of the calo­ries pro­duced for hu­man con­sump­tion — that’s not a whole lot of juice for the squeeze.

Of all the fish­ing-gear types mon­i­tored in the study, longlin­ing was the most wide­spread and was ob­served in 45 per­cent of the ocean.

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