Kelp Gulls and monofilament lines: Interactions and fisher perceptions at recreational fishing sites in coastal Patagonia, Argentina

Abstract

Recreational fishing is practiced in many coastal marine areas of Argentina, although the contribution of this activity to marine debris pollution and its effects on wildlife are largely unquantified. Previous studies have shown that discarded monofilament lines can adversely affect coastal birds. Based on coastal surveys conducted between December 2020 and March 2021, this study quantified lost and discarded monofilament lines at four frequently visited recreational fishing sites in coastal Chubut, Argentine Patagonia, and examined the interaction between the activity and the opportunistic Kelp Gull (Larus dominicanus). A total of 690 monofilament lines were recorded, of which 17.9 % and 13.4 % had hooks or sinkers, respectively, and their number varied significantly among fishing sites. Adult and young Kelp Gulls were recorded in almost all surveys in the four sites, mainly resting (>80 %) and to a lesser extent feeding on food derived from the fishing activity (<16 %). No entangled individuals were recorded. However, an online survey directed at recreational fishers revealed that Kelp Gulls frequently take advantage of food derived from the activity and collide with set fishing lines and, to a lesser extent, they become entangled. All respondents expressed interest in the implementation of marine debris management measures. Recreational fishing does not appear to be a threat to Kelp Gull populations at the current level of activity. Our results highlight recreational fishing as a source of marine debris pollution and the need to implement actions to mitigate the potential impact of monofilament lines on Kelp Gulls and coastal ecosystems in Patagonia.