Ban the bottom trawling, keep the lobsters crawling!

What is bottom trawling?  

Bottom trawling is a fishing method in which boats drag large weighted nets along the sea floor. It’s highly unsustainable as it scrapes the bottom of the ocean and destroys habitats on the path. Vulnerable habitats require centuries to recover as one swipe can destroy pillars of the ecosystem. Bottom trawling results in reduction of complexity, productivity, and biodiversity, especially in areas with corals and sponges (1).

Another damage is the by-catch, incidental removal of non-target organisms. Bottom trawling is very efficient and favored by large commercial fisheries as all creatures in its path are picked up. Annual estimation of 4.2 million tonnes of discarded by-catch comes from bottom trawls.

The role of politics

Bottom trawling is practised in both developed and developing nations. Recently, it’s revealed that 97% of UK marine protected areas (MPA) are subject to bottom-trawling. MPAs are created to protect vital ecosystems and species, yet bottom trawling is happening in71 out of 73 offshore MPAs around the UK (2). UK government was criticized for misleading the public since they set up MPAs but didn’t ban fishing in these areas. The Marine Management Organization in UK is currently consulting on by-laws prohibiting bottom-towed gear (3).

Indonesia is a great country to shine light upon when discussing politics in conservation. Susi Pudjiastuti, the Minister of Marine Affairs and Fisheries from 2014-2019, is a political superstar. During her time in office, her mission was to stop exploitation of marine biodiversity and protect coastal fish spawning sites. Susi was known for her policies of blowing up and sinking foreign fishing vessels that had been seized poaching in Indonesia’s waters (4). Additionally, she banned the use of cantrang, a seine net used in trawl fishing. Results of her aggressive anti-illegal fishing policies were >25% reduction in total fishing effort and a striking >90% reduction in the foreign illegal fishing hours (5). Her “no compromise” attitude angered many stakeholders including fisheries companies both in Indonesia and abroad, lawmakers, and civil groups, which likely contributed to Susi not being reappointed (6). The new minister Edhy Prabowo plans to revise policies on banning unsustainable fishing gear and sinking foreign poaching boats (4). His actions will likely counter Susi’s effort over the years and reintroduce the pressure of overfishing to Indonesian waters. This will likely benefit large-scale fishery instead of small-scale fishers that make up most of Indonesian fisheries. The impact of switch in political powers in Indonesia is a great example of politics being an important driver of conservation efforts. Without policies and regulations, individual efforts are unable to achieve large-scale impact.

Positive impact of the ban

Researches were conducted after banning bottom trawling. An article observed dominant predatory mantis shrimp species in Hongkong 3.5 years after the ban and found significant increase in mean weight, carapace length and proportion of large-sized individuals (7). Another research found higher species diversity and increased abundance and lengths of some bivalves in benthic community along Dutch coastal zone after a 5-year ban (8). Though long-term changes might be subtle, bottom trawling ban indeed has positive impacts on coastal restoration. However, it’s still used in many areas for efficiency and good profit. Without well-managed regulation and support from government, ecosystem will continue being destroyed. This is why raising awareness and utilizing our political stance are extremely important.

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References

1. Prokop, R. (2017). Bottom trawling. Retrieved February 03, 2021, from https://usa.oceana.org/bottom-trawlingLinks to an external site.
2. McVeigh, K. (2020). Revealed: 97% of UK marine protected areas subject TO BOTTOM-TRAWLING. Retrieved February 03, 2021, from https://www.theguardian.com/environment/2020/oct/09/revealed-97-of-uk-offshore-marine-parks-subject-to-destructive-fishingLinks to an external site.
3. Harrabin, R. (2021). Bottom trawling ban for key UK fishing sites. Retrieved February 03, 2021, from https://www.bbc.com/news/science-environment-55894608Links to an external site.
4. Ambari, M. (2019). Indonesia's new fisheries Minister may go easy ON Trawl Nets, poachers' boats. Retrieved February 03, 2021, from https://news.mongabay.com/2019/11/indonesia-fisheries-minister-edhy-susi-pudjiastuti-sinking-net-ban/Links to an external site.
5. Cabral, R. B., Mayorga, J., Clemence, M., Lynham, J., Koeshendrajana, S., Muawanah, U., . . . Costello, C. (2018). Rapid and lasting gains from solving illegal fishing. Nature Ecology & Evolution, 2(4), 650-658. doi:10.1038/s41559-018-0499-1
6. Scarpello, F. (2020). Research explains WHY SUSI Pudjiastuti was left out of Jokowi's second-term cabinet. Retrieved February 03, 2021, from https://theconversation.com/research-explains-why-susi-pudjiastuti-was-left-out-of-jokowis-second-term-cabinet-143373Links to an external site.
7. Tao, L. S. R., Lui, K. K. Y., Lau, E. T. C., Ho, K. K. Y., Mak, Y. K. Y., Sadovy de Mitcheson, Y., & Leung, K. M. Y. (2018). Trawl ban in a heavily exploited marine environment: Responses in population dynamics of four stomatopod species. Scientific Reports, 8(1), 17876-14. doi:10.1038/s41598-018-35804-7
8. Bergman, M. J. N., Ubels, S. M., Duineveld, G. C. A., & Meesters, E. (2015). Effects of a 5-year trawling ban on the local benthic community in a wind farm in the dutch coastal zone. ICES Journal of Marine Science, 72(3), 962-972. doi:10.1093/icesjms/fsu193