The Dangers Of Derelict Traps
Here at Faunalytics, we’ve talked about marine debris, but most of the discussion has centered on plastic “microdebris” coming from trash. There are other kinds of marine debris that impact animals (including humans), including everything from abandoned vessels to large patches of plastic that have formed virtual islands. One of the most common types of human-made marine debris is derelict fishing traps (DFTs) that have been left in the water. While less obvious than the patches of plastic that gain media attention, DFTs may have a bigger impact on marine life than we think. This abandoned gear continues to capture fish for indeterminable amounts of time, something known as “ghost fishing.” It’s a phenomenon that results in loss of both the original targeted species as well as non-target species; it can also damage the sea floor.
Unfortunately, despite the potential seriousness of these impacts, there is “a surprising lack of published data examining the extent of the problem,” including both ecological and economic impacts. There also haven’t been many attempts to bring together the current data on the topic of DFTs. To try to address this, the authors of this review wanted to make a first step in gaining a “specific understanding” of the issue, by focusing on traps (as opposed to other kinds of derelict gear) and comparing different trap fishery zones. Examining seven previous studies, the researchers wanted to know how many DFTs exist in a given fishery, where they are, and what impact they have. Compiling this data is challenging because the studies use different forms of data gathering that do not necessarily match each other, making mortality estimates especially difficult. Though they made various adjustments to try to account for these differences, the authors note that their analysis is “mainly qualitative and highlights the need for standard reporting metrics to facilitate comparisons.”
What they found was that the average number of derelict traps can vary widely by region, with anywhere from five to 47 DFTs per square kilometre. Those are average numbers, and in specific areas the number could range as high as 28-75 DFTs per square kilometre. Understanding how long the DFTs would engage in ghost fishing was another aspect studied, and this was impacted by factors like the trap design and how much the traps had degraded over time. Overall, rates of ghost fishing (that is, number of traps ghost fishing / total DFTs) ranged from 5%-40%. This shows a significant potential for both short- and long-term impacts, as those traps can potentially continue to ghost fish for up to six years, depending on the region.
What is to be done? Many animal advocates no doubt understand that there would be no derelict traps if there was also no trap fishing. However, in the absence of putting an end to those fisheries (which is not on these researchers’ agenda), the researchers recommend a range of solutions. These include redesigning traps to include escape panels as well as creating low-cost, easy disposal options as “incentive to reduce improper disposal.” The researchers also recommend the standardization of measurements that would help to assess the problem. For aquatic wildlife advocates, this study may bring a new issue to the forefront and highlight just how much it deserves our attention.