Description of tuna gillnet capacity and bycatch in the IOTC Convention Area
Fisheries in the Indian Ocean are dominated by artisanal activities. Most of the coastal developing nations bordering the Indian Ocean rely on artisanal fisheries for the provision of food and income. The dominance of artisanal fleets in the region brings about, however, large uncertainty in data collection. The lack of data may undermine the scientific process and the effectiveness of the subsequent conservation and management measures (CMM). Part of the artisanal fleet possess high navigational autonomy and large production means e.g. gillnets exceeding allowed lengths. This activity is not yet officially defined as semi-industrial and is not subject to restrictions in place for industrial vessels (Vessel Monitoring System and restrictions on fishing capacity). High fishing pressure in coastal areas may also motivate expansion of activities in the high seas. This is particularly relevant in the cases of Iran and Pakistan (Anderson 2014). The inability of enforcing controls in the high seas and national EEZs, the relative ease to access to the gillnet activity and the low exigencies in quality of the local markets are likely encouraging the building of fishing capacity in artisanal and semi-industrial fisheries, which utilizes gillnet as the predominant fishing technology. Local markets absorb catches that otherwise will be discarded due to low value or lack of local demand. Thus, the low selectivity of this fishing technology may not be an impediment for the expansion of this modality of fishing. This constitutes a threat for tuna and tuna-like species due to the high bycatch of young tuna individuals and other bonny fish, and for biodiversity as a significant share of the bycatch comprises sharks, marine mammals, turtles, and to a lesser extent seabird. One of the main difficulties to be faced to accurately manage the fisheries in this region is the institutional technical capacities of coastal nations to collect and submit data for artisanal fisheries e.g. lack of logbooks, observers on board and VMS in most cases. Despite the scarce data available it seems that gillnet fisheries in the Indian Ocean appear to have a meaningful level of bycatch of sensitive species much higher than that of other fishing technologies such as purse seine, pole and line and even longline (Ardill et al 2013). The real size of the artisanal fishing capacity remains uncertain despite the efforts conducted by diverse institutions and scientists, inter alia Moreno and Herrera (2013), to estimate the size of the artisanal fleet, and especially of the gillnet sector. The need to assess the extent of gillnet fisheries has been remarked by the IOTC WPEB, which has recommended to freeze or reduce gillnet fishing capacity and effort until sufficient information is available to assess the impact of this fishing modality on target and non-target resources. The present study aims at describing and analysing the situation of fishing capacity and bycatch of gillnet fisheries in the IOTC area of competence. It conducts a comprehensive revision of the scientific and technical literature, the IOTC reports of the scientific and compliance committees, national reports, Conservation and Management Measures (CMM) and statistical data on nominal catches and available data on fishing capacity.