Dear colleagues, we announce the publication of a comprehensive report on trawling:
Bearzi, G., Bonizzoni, S., Reeves, R.R. 2024. The trawl supremacy: hegemony of destructive bottom trawl fisheries and some of the management solutions. OceanCare, Wädenswil, Switzerland. 134 pp. While this long report does not feature marine mammals primarily, it does contain sections on bycatch of cetaceans and pinnipeds in trawl gear (in Chapter 5) and the relevant mitigation methods (in Chapter 10). Colleagues working on marine mammal conservation may also be interested in our review of the negative effects of trawling on the marine environment generally, which includes impacts on marine mammal habitat and prey. The report is free, and it can be downloaded from http://www.oceancare.org/trawlsupremacy as well as through ResearchGate. Cheers, Giovanni, Silvia and Randy ABSTRACT --- Trawling is a type of fishing characterized by the active towing of nets by a moving boat. Trawl nets vary greatly in size and shape, and they target a wide variety of species, including bottom-dwelling fish, crustaceans and molluscs, pelagic and semi-pelagic schooling fish, and deep-water fauna. In this report, we provide a general overview on towed gear, but we focus more specifically on bottom trawling: the towing of nets along the seabed. Bottom trawling has become a cornerstone of global food supplies, accounting for more than one quarter of global fishery landings. In 2016, this equated to over 30 million tonnes of seafood. In several European and African countries, half of fishery landings come from bottom trawling. Bottom trawling, however, has long been known to be detrimental to marine life. It was regarded as a destructive fishing method since the early 14th century, and was often vocally opposed by communities of fishers who saw it as a threat to marine resources and their own livelihoods. The introduction of steam and diesel engines (in the 1830s and 1930s, respectively) marked the modern era of trawling. Engine-powered trawling increased rapidly during the 1960s, and by the 1980s large fleets of trawlers were combing the global oceans. Today's bottom trawlers can operate virtually anywhere, from shallow inland channels and rivers to deep offshore waters. Countless scientific studies, encompassing decades of fishery research, have documented the harmful nature of bottom trawling, with substantial cumulative evidence of damage to marine species and ecosystems. Bottom trawling reduces the biomass, diversity and complexity of benthic communities, and the action of trawl gear on the seabed causes dramatic mechanical and chemical alterations, compromising the seabed's functionality and productivity. In addition to the target species, most types of trawl gear take unwanted species, such as threatened elasmobranchs, sea turtles, seabirds and marine mammals. Apart from these biological impacts, recent studies indicate that bottom trawling has a considerable carbon footprint, with high direct and indirect greenhouse gas emissions contributing to climate disruption. Information on the harmful effects of bottom trawling has resulted in public and institutional awareness of environmental damage, and in restrictions that have sometimes included complete bans. Trawling is often prohibited in the most coastal and shallow waters. However, regulations and enforcement levels vary greatly across areas, and environmental protection measures are often ineffective -- to the point that the intensity of bottom trawling can be higher inside than outside some Marine Protected Areas. In this report, we review the evidence of how bottom trawling affects marine life and human life. We also summarize some of the primary management approaches that could help mitigate the harmful effects of trawling -- consistent with international commitments to protect the marine environment. We conclude that the amount of seafood produced by bottom trawling can no longer justify or excuse the pervasive damage caused to marine ecosystems and communities of small-scale fishers, and we advocate the use of less destructive fishing gear, combined with the creation of areas protected from harmful fishing practices, and more sustainable strategies to 'feed the world'. _______________________________________________ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
