Mapping by satellite pinpoints danger zones for turtles

photograph by Michael Patrick O'neill/Alamy

Many  migratory species in the ocean face a constant battle with fisherman.  However, satellite and fisheries data can help prevent some of these battles.  Some of the animals that are most affected by bycatch include seabirds, turtles, dolphins and cetaceans.  Recently, fisheries and satellites have been tracking leatherback turtles (Dermochelys coriacea) in the Atlantic Ocean and trying to prevent these unintended captures. 

The Atlantic Ocean is home to the last large populations of leatherback turtles.  Because these turtles have a migratory nature and are considered to be the world’s largest turtle, they are very vulnerable to unintended capture by fisherman.  In the past, understanding how to protect these turtles has been difficult because much of the bycatch is not reported by fisherman and the turtles cover very wide paths in the Atlantic.  The satellites have tracked leatherback turtles from 1995 to 2010 to find out many of the zones that the turtles regularly occupy, and to identify some areas where they may clash with fisherman.

A conservation scientist named Brendan Godley explained that the largest obstacle to protecting the turtles has been knowing where, when, and in what fisheries the bycatch is taking place.   He has published research that pinpoints four sites in the north Atlantic and five sites in the south Atlantic that are high-risk areas for leatherback turtles.  These high-risk sites include the economic zones shared by 12 different countries including the US and UK.  In these economic zones, many of which overlap with high-risk turtle zones,  longlines are cast regularly for tuna and other commercial fishing occurs here.

Action is being taken to protect the populations of these leatherbacks in the Atlantic, because the populations in the Pacific Ocean have nearly been wiped out and are considered critically endangered by the International Union for the Conservation of Nature.  Another scientist named Matthew Witt said that reversing the trend in the Pacific is almost impossible, but with his research they are trying to prevent this from happening in the Atlantic. 

His team was able to provide satellite data from over 100 turtles, showing their standardized tracks and also including longline-fisheries data to identify areas of low, medium and high interaction between turtles and humans.  The team then made a map that covers the Atlantic in a grid with squares that are 5 degrees latitude by 5 degrees longitude. 

Then, Rebecca Lewison, a conservation ecologist, backed up Witt’s team research by stating that his analysis makes it harder for governments to ignore the danger that bycatch poses to migratory species, including the leatherback turtles.  She also pointed out that ocean-wide scales like this one have to be taken into consideration if people are serious about preventing the extinctions of pelagic species. 

In summary, these scientists are all working together to prevent the bycatch of migratory species.  If they know where the turtles and other species are regularly found, fisherman can reduce bycatch by making better decisions on where to fish.  Maps like the one created in this study from satellite data can be used as a tool to prevent fisherman bycatch.  Longlines and other coastal fishing gear such as trawls pose the greatest risk to turtles, and future research can be done to incorporate these dangers into the maps as well. 

Resource

Related PDF