It’s an article packed full of potential contention as it speaks to a variety of issues involving fisheries management. So thank God we are dealing with a charismatic marine species or we just may be contemplating their extinction. But then again, perhaps we are doing just that since all 7 species of marine turtles are listed under the Endangered Species Act. So what does that mean when millions of sea turtles are caught as bycatch in just 18 years? I think it means the status quo is definitely due for an overhaul to say the least.
Bycatch. It’s a word that sounds rather innocuous as it rolls off the tongue, but clearly does not do justice to the staggering amount of life that is instantly converted to simple biological waste. It’s a problem that amounts to tonnes, in the neighborhood of several million per year. And again I say thank God because the widely popular sea turtle may be able to help shine the light on an ever growing problem responsible for population declines in multiple species. Well, at least I hope so.
In Global Patterns of Marine Turtle Bycatch, gillnets, longlines, and trawl fisheries are providing us with a perspective that we would probably rather ignore. Unfortunately the out of sight out of mind attitude is not helping the sea turtle situation and it reminds me of an old mantra I used, “The catch of the day may cost more than you think.” In this scenario, that cost is…
The total reported global marine turtle bycatch (1990-2008) was ∼85,000 turtles, but due to the small percentage of fishing effort observed and reported (typically <1% of total fleets), and to a global lack of bycatch information from small-scale fisheries, this likely underestimates the true total by at least two orders of magnitude.
And after looking at the data I am left wondering how many sea turtles are actually killed or die as a result of wounds incurred by coming into contact with gillnets, longlines and trawls. I can imagine it is only palatable when wearing a pair of rose colored glasses. But as far as the research goes, there was insufficient data to incorporate mortality rates.
The study found the bycatch per unit effort (BPUE) varied greatly depending upon the region and fishing method employed. In fact , it identified certain hotspots that are a cause for concern and highlight the need for fisheries management intervention.
Based on reported sea turtle bycatch, the maximum BPUEs found for each fishing method are as follows:
- 2.2 turtles per set for gillnets in the Mediterranean Sea
- 19.3 turtles per 1,000 hooks for longlines in the eastern Pacific Ocean
- 7.2 turtles per haul for trawls in the southwest Atlantic Ocean
“Targeted action to reduce turtle-gear interactions is essential for population persistence, and is already underway for some fleets…our study revealed that reports of longline bycatch are two-fold more common than reports of bycatch in either trawls or gillnets.”
Having the data means we have no more excuses for not developing, continuing to develop and implementing a conservation plan that is both regional and fishing gear specific. The plan must be more than focusing on turtle excluder devices, but must include other innovative management techniques on the lines of time-area closures, etc. And since time is of the essence and marine turtle populations are at risk, immediate action is required.
Wallace, B., Lewison, R., McDonald, S., McDonald, R., Kot, C., Kelez, S., Bjorkland, R., Finkbeiner, E., Helmbrecht, S., & Crowder, L. (2010). Global patterns of marine turtle bycatch Conservation Letters DOI: 10.1111/j.1755-263X.2010.00105.x