Interactions between breeding gulls and monofilament lines at one of the main recreational fishing sites in Argentina.

Monofilament fishing lines lost or discarded during recreational fishing activities often result in negative impacts on marine organisms. We assessed the interactions between Kelp and Olrog's gulls (Larus dominicanus and L. atlanticus, respectively) and recreational fishing at Bahía San Blas, Argentina. Monofilament lines constituted 61 and 29 % of total debris items recorded along beaches in the low and high fishing seasons, respectively. A total of 61 balls of tangled lines were also found within Kelp and Olrog's gull colonies. No Olrog's Gulls but nine Kelp Gulls were found tangled with monofilament lines within colony boundaries, seven of which were caught in vegetation. No Kelp or Olrog's gulls foraging in recreational fishing areas were observed tangled with lines. Monofilament lines did not negatively affect gull populations during the study period, but actions are needed to correctly manage their disposal given the relevance of Bahía San Blas as a recreational fishing area in the region.

Anthropogenic debris in Kelp Gull and other seabird nests in northern Patagonia, Argentina.

Anthropogenic debris is used as nesting material by many seabirds and may result in negative impacts. We assessed the frequency of occurrence of debris (>5 mm) in Kelp Gull (Larus dominicanus) nests at six locations along 2400 km of the Argentine coast, at different distances from urban centres, and in nests of other seven seabird species nesting syntopically. Frequencies in Kelp Gull nests were in general relatively low, ranging between 3.3 and 37.5%, and differed significantly among colonies. No relationship was found between frequency and distance to urban centres. Debris were recorded with frequencies of less than 19.2% in nests of Olrog's Gulls (L. atlanticus), Dolphin Gulls (L. scoresbii), Imperial Cormorants (Leucocarbo atriceps) and Magellanic Penguins (Spheniscus magellanicus), but not in nests of Neotropical Cormorants (Nannopterum brasilianus), Rock Shags (Leucocarbo magellanicus) and Southern Skuas (Catharacta antarctica). This information obtained along a wide coastal sector provides a baseline for future monitoring.

Patterns of plastic ingestion in Kelp Gull (Larus dominicanus) populations breeding in northern Patagonia, Argentina.

Human waste is a global concern, and volumes are growing rapidly. For opportunistic species, like many birds, urban waste offers alternative food which in turn may lead to plastic ingestion with potential negative effects. We assessed the incidence of plastics and other marine debris in breeding Kelp Gull (Larus dominicanus) diet at nine colonies located along ~2400 km of coastline from southern Buenos Aires to southern Chubut, Argentina, using regurgitated pellets (n = 2355) and chick stomach content samples (n = 588). Plastics were recorded at all colonies, and incidence varied between 0.0 and 16.2% in adult pellets and 0.0-12.5% in chick stomach content samples, depending on the colony, breeding stage and year. Contrary to our expectation, incidence of debris including plastics in Kelp Gull diet was relatively low despite its opportunistic feeding habits and widespread use of refuse dumps, even at colonies located close (<10 km) to these anthropogenic food subsidies.

Does trawl fisheries affect the diet of fishes? A stable isotope analysis approach.

Trawling is the main fishing practice worldwide and its ecosystem effects have been raising concern over the past decades. Long-term impacts can be monitored through changes in the trophic structure, and several studies evaluated trophic level (TL) shifts in fish populations between trawled and untrawled environments. However, published results are contrasting. We performed a metanalysis integrating all available studies that evaluated TL shifts in fishes between trawled and untrawled environments and conducted a local study comparing several features of the trophic ecology in two species of fishes. According to the metanalysis, TL does not change significantly with trawling. In contrast, the local study showed higher TLs and broader isotopic niches in the trawled environment. Diet reconstruction indicated a potential consumption of hake, the main discard component, at the trawled environment. All the studies used in the metanalysis were conducted in the Northern Hemisphere, whereas the local study represents the first data available from the Southern Hemisphere. As industrial commercial fisheries in Argentina are relatively recent, it is possible that our data are capturing the initial stage of ecological changes induced by trawling, compared with the historical fisheries located at the Northern Hemisphere.

Persistent organic pollutants in sediments, intertidal crabs, and the threatened Olrog's gull in a northern Patagonia salt marsh, Argentina.

Persistent organic pollutants (POPs) are of great concern for the environment. In this study we (a) determine levels and distribution of OCPs, PCBs, and PBDEs in sediments and two crab species (Neohelice granulata and Cyrtograpsus altimanus), (b) assess bioaccumulation in crabs, and (c) explore the occurrence of POPs in the Near Threatened Olrog's gull (Larus atlanticus) chicks and eggs in one of the most important salt marsh environments in the South West Atlantic. Sediments, crabs, and gull chicks and eggs showed POPs presence at low levels; being α-endosulfan, PCB-153, and BDE-47 the most represented compounds. In sediments, pollutant concentrations were lower than those reported in Canadian guidelines for the protection of the aquatic life. POP bioaccumulation was recorded in crabs, suggesting a risk to upper trophic level predators. Further studies are needed to understand the trophic effects of POPs in San Blas bay, particularly on the threatened Olrog's gull.

Kelp Gulls (Larus dominicanus) killed and injured by discarded monofilament lines at a marine recreational fishery in northern Patagonia.

Among marine debris, monofilament fishing lines often result in negative impacts on marine organisms. We characterized marine debris and incidence of lost and discarded monofilament lines along beaches used by recreational fishers, and report the impact of lines on Kelp Gulls (Larus dominicanus) at the Bahía San Blas protected area, site of one of the main shore-based recreational fisheries of the southwestern Atlantic. Over 55% of the marine debris recorded originated from recreational fishing activities. Balls of tangled monofilament lines were found at a rate of 40.5 items per km. A total of 27 adult Kelp Gulls were found entangled with monofilament. All individuals were tangled to vegetation within colony boundaries. Four of the gulls had a monofilament line protruding from the bill, showing that they may be also killed when trying to obtain bait. Our results indicate that lost or discarded monofilament lines in the Bahía San Blas recreational fishing area result in undesired impacts on coastal wildlife.