Illegal fishing bycatch overshadows climate as a driver of albatross population decline

Abstract

Effective management of albatross populations requires understanding the impacts of environmental factors on albatross demographics. An integrated modelling approach incorporating multiple data sources can further the understanding of albatross demographics by incorporating error from all components of modeling, and help distinguish between variability related to one factor (e.g. environment) from that of another factor (e.g. density dependence). We applied such an integrated, spatially-explicit population model to quantify the impact of environmental conditions (sea surface temperature, SST), fisheries, and density dependence on a black-browed albatross Thalassarche melanophris population breeding on Kerguelen Island, southern Indian Ocean for the period 1950 to 2011. The model was structured by sex, age-class, and breeding stage, with a 5° × 5° spatial scale and monthly temporal scale. All parameters were estimated within a maximum likelihood framework. This includes estimation of seabird bycatch rates of each of 5 fishing super-fleets, grouped by gear type and reported bycatch rates: (1) Japanese pelagic longline, (2) other pelagic longline, (3) legal demersal longline, (4) trawl, and (5) illegal, unreported, and unregulated (IUU) demersal longline. A decline in the Kerguelen black-browed albatross population occurred between the mid-1990s through the mid-2000s. Our analysis attributes the majority of modelled bycatch to the IUU demersal longline super-fleet operating near Kerguelen Island for this period. Including SST during the incubation period indicated that warm SST favors high breeding success. These results indicate that effective management requires an integrated understanding of the impacts of the environment as well as illegal and legal fishing activities on vulnerable populations. KEY WORDS: Demographics • Integrated population model • Illegal, unreported, and unregulated (IUU) fishing • Black-browed albatross • Thalassarche melanophris • Kerguelen Island Resale or republication not permitted without written consent of the publisher This authors' personal copy may not be publicly or systematically copied or distributed, or posted on the Open Web, except with written permission of the copyright holder(s). It may be distributed to interested individuals on request.

The Intersection Between Illegal Fishing, Crimes at Sea, and Social Well-Being

“…For example, The Southern Ocean was once a hotspot of IUU fishing activity, with a substantial illegal catch of Patagonia Toothfish reported from the mid 1990s until the late 2000s (Österblom et al, 2010). Toothfish stocks came close to commercial collapse, seabirds such as albatross were significantly threatened due to by-catch by illegal fishers, and licensed fishers lost hundreds of millions of dollars (CCAMLR, 2002;COLTO, 2003;Michael et al, 2017). A consolidated and collaborative effort, facilitated through a network of state actors, the fishing industry, and environmental non-governmental organizations reduced the prevalence of IUU fishing in the Southern Ocean (Österblom et al, 2014).…”

Evaluating the effectiveness of a large multi‐use MPA in protecting Key Biodiversity Areas for marine predators

“…Conservation measures in many of these areas, beyond seasonal closures, require seabird bycatch mitigation measures to be used within the fisheries which are similar to those in the SGSSI MPA, all of which have greatly reduced seabird bycatch rates. Concerns which still remain for many of these species, however, are the effects of distant-water pelagic longline fisheries and IUU fishing, mostly in waters beyond the jurisdiction of MPAs (Clay et al, 2019;Michael et al, 2017;Österblom & Bodin, 2012). This threat is believed to be a key driver in continued declines of some albatross and petrel populations, including those at SGSSI (Table 1) (Krüger et al, 2018;Pardo et al, 2017;Poncet et al, 2017).…”

Progress and challenges in eliminating illegal fishing

“…Some fishers use destructive fishing methods such as explosive “bomb” or cyanide fishing, both of which damage the marine environment and are unsustainable fishing practices (Petrossian, 2015). The act of illegal fishing contributes to by‐catch as the fishers often focus on only catching targeted species, potentially ignoring more environmentally friendly fishing practices, with dire consequences for other species such as seabirds (Michael et al., 2017). Derelict fishing gear may result from illegal activities and is a large contributor of ship‐sourced marine debris which is estimated to have population level impacts on protected marine species (Richardson et al., 2018; Wilcox et al., 2015).…”