Interspecific variability in plastic ingested by Procellariiformes off the Uruguayan coast.

We assessed the interspecific variability in plastic ingested by albatrosses and petrels using bycaught birds from fisheries of the Southwest Atlantic. From 107 stomachs examined, 4.17 % of the albatrosses and 62.86 % of the petrels contained plastics. Macronectes halli and Ardenna gravis had 100 % of occurrence. They were followed by Procellaria conspicillata (75 %), Procellaria aequinoctialis (47.62 %), T. melanophris (4.35 %) and T. chlororhynchos (0 %). The most common groups of plastics by size, type and color, were mesoplastics (5-20 mm), user plastics and white-clear items, respectively. Larger species tend to ingest larger items with greater surfaces. Together with evidence from other studies, our results indicate that interspecific differences in the occurrence and the dimensions of plastics appear to be associated with digestive tract morphology, foraging techniques, body size, interaction with fishing vessels, and with the availability of plastics at the sea surface.

Trade-offs between bycatch and target catches in static versus dynamic fishery closures.

While there have been recent improvements in reducing bycatch in many fisheries, bycatch remains a threat for numerous species around the globe. Static spatial and temporal closures are used in many places as a tool to reduce bycatch. However, their effectiveness in achieving this goal is uncertain, particularly for highly mobile species. We evaluated evidence for the effects of temporal, static, and dynamic area closures on the bycatch and target catch of 15 fisheries around the world. Assuming perfect knowledge of where the catch and bycatch occurs and a closure of 30% of the fishing area, we found that dynamic area closures could reduce bycatch by an average of 57% without sacrificing catch of target species, compared to 16% reductions in bycatch achievable by static closures. The degree of bycatch reduction achievable for a certain quantity of target catch was related to the correlation in space and time between target and bycatch species. If the correlation was high, it was harder to find an area to reduce bycatch without sacrificing catch of target species. If the goal of spatial closures is to reduce bycatch, our results suggest that dynamic management provides substantially better outcomes than classic static marine area closures. The use of dynamic ocean management might be difficult to implement and enforce in many regions. Nevertheless, dynamic approaches will be increasingly valuable as climate change drives species and fisheries into new habitats or extended ranges, altering species-fishery interactions and underscoring the need for more responsive and flexible regulatory mechanisms.

New records and range extension of the Portuguese dogfish Centroscymnus coelolepis in the south-western Atlantic Ocean, with comments on its morphology.

The Portuguese dogfish Centroscymnus coelolepis is a wide-ranging deep-water shark and a common by-catch component of the catches of several mid- to deep-water fisheries. In the present study, two new records from the south-western Atlantic Ocean are reported based on specimens caught by bottom-longline fishing vessels operating in the Argentinean-Uruguayan Common Fishing Zone. Species identification based on morphology and detailed morphometrics, as well as molecular data are presented for one of the specimens. The distribution of the species over the south-western Atlantic is discussed on the basis of the available bibliography and a thorough revision of museum collections. The records presented here expand the species' previously acknowledged distribution southwards, from around 21° S to at least 38° S, suggesting it occurs continuously along the shelf break of eastern South America. However, given the limited access to specimens of deep-water sharks in the region, the abundance and real extent of C. coelolepis distribution in the south-western Atlantic as well as its interaction with deep-water fisheries remain to be fully assessed.

Effectiveness of tori line use to reduce seabird bycatch in pelagic longline fishing.

Industrial longline fisheries cause the death of large numbers of seabirds annually. Various mitigation measures have been proposed, including the use of tori lines. In this study the efficiency of a single tori line to reduce seabird bycatch was tested on pelagic longline vessels (25-37m length). Thirteen fishing trips were carried out in the area and season of the highest bycatch rates recorded in the southwest Atlantic (2009-2011). We deployed two treatments in random order: sets with a tori line and without a tori line (control treatment). The use of a tori line significantly reduced seabird bycatch rates. Forty three and seven birds were captured in the control (0.85 birds/1,000 hooks, n = 49 sets) and in the tori line treatment (0.13 birds/1,000 hooks, n = 51 sets), respectively. In 47% of the latter sets the tori line broke either because of entanglement with the longline gear or by tension. This diminished the tori line effectiveness; five of the seven captures during sets where a tori line was deployed were following ruptures. Nine additional trips were conducted with a tori line that was modified to reduce entanglements (2012-2016). Seven entanglements were recorded in 73 longline sets. The chance of a rupture on these trips was 4% (95% c.l. = 1-18%) of that during 2009-2011. This work shows that the use of a tori line reduces seabird bycatch in pelagic longline fisheries and is a practice suitable for medium size vessels (~25-40m length). Because the study area has historically very high bycatch rates at global level, this tori line design is potentially useful to reduce seabird bycatch in many medium size pelagic longline vessel fishing in the southern hemisphere.