A substantial level of non-target species are often caught in tuna longline fisheries, which can therefore impose a heavy ecological burden on pelagic fish communities. However, limited studies have ...quantitatively examined the scale of bycatch varying across fishing fleets and areas in regional tuna longline fisheries, as data are often sparse. We used scientific observer data to analyze the discard and bycatch patterns of Chinese tuna longline fleets in the Pacific Ocean by applying general statistical analysis and spatial hotspots analysis. A total of 9971 sets were observed, representing 1.56% of the total efforts. Of 435,156 individuals, 30.4% were recorded as bycatch, and 15.8% were discarded. The majority of bycatch was other bony fishes (15.5%) and sharks (7.3%). Bycatch and discard rates of the bigeye tuna (Thunnus obesus, BET) fleet were larger than that of the albacore (Thunnus alalunga, ALB) fleet. The highest bycatch rates of other bony fishes and elasmobranchs most often occurred in the western and central temperate Pacific and the eastern tropical Pacific, respectively. Most marine turtles and mammals were caught by the BET fleet in the Tropical Pacific, and the bycatch of seabirds often occurred in the Temperate Pacific. Low bycatch rates but high discard mortality of marine mammals, turtles, and sea birds were found. Bycatch rates were estimated by fleet, seasons, and areas, with the rates of marine turtles ranging from 0 to 0.024 per 1000 hooks, and those of sea birds ranging from 0 to 0.228 per 1000 hooks. Six bycatch hotspots, identified in this study, should be considered in future management and conservation planning. Implementing measures such as live releasing bycatch, reducing the fishing efforts in the area with high bycatch rate, optimizing monitoring programs, and allocating observers more widely in areas where there is more bycatch are necessary.
•Bycatch accounted for 30.4% of the total catch, with a total discard rate was 15.83% in Chinese tuna longline fisheries in the Pacific Ocean.•Bycatch and discard rates varied between different fleets.•Several bycatch hotspots were identified for further consideration in fisheries management and conservation.•Bycatch monitoring and mitigation measures should be improved to achieve objectives.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The genetic identification of evolutionary significant units and information on their connectivity can be used to design effective management and conservation plans for species of concern. Despite ...having high dispersal capacity, several seabird species show population structure due to both abiotic and biotic barriers to gene flow. The Kelp Gull is the most abundant species of gull in the southern hemisphere. In Argentina it reproduces in both marine and freshwater environments, with more than 100,000 breeding pairs following a metapopulation dynamic across 140 colonies in the Atlantic coast of Patagonia. However, little is known about the demography and connectivity of inland populations. We aim to provide information on the connectivity of the largest freshwater colonies (those from Nahuel Huapi Lake) with the closest Pacific and Atlantic populations to evaluate if these freshwater colonies are receiving immigrants from the larger coastal populations. We sampled three geographic regions (Nahuel Huapi Lake and the Atlantic and Pacific coasts) and employed a reduced-representation genomic approach to genotype individuals for single-nucleotide polymorphisms (SNPs). Using clustering and phylogenetic analyses we found three genetic groups, each corresponding to one of our sampled regions. Individuals from marine environments are more closely related to each other than to those from Nahuel Huapi Lake, indicating that the latter population constitutes the first freshwater Kelp Gull colony to be identified as an evolutionary significant unit in Patagonia.
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High numbers of seabirds are killed annually worldwide in longline fisheries. In the Mediterranean, this mortality is seriously affecting the viability of seabird populations, in particular of the ...three endemic shearwaters. Even so, there is currently no specific seabird mitigation requirements for the longline fleet operating in this area. From 2013 to 2014, we assessed the efficiency and practical applicability of four mitigation measures on artisanal demersal longliners targeting European hake (Merluccius merluccius) in the western Mediterranean: night setting, tori line, weighted lines and artificial baits. We performed fifty-two pairs of experimental (with the tested mitigation measure) and control settings (without any measure), and compared their effects on seabird interactions and fish catches. In addition, we estimated the longline sink rates and the seabird access area to baited hooks in different longline configurations. Night setting reduced bycatch risk without affecting target and non-commercial fish catches. The tori line may have reduced the bycatch risk by displacing bait attacks beyond the end of the line, but at this distance shearwaters could still access to the baits and the streamers did not deter birds under calm wind conditions. Weighted lines increased sink rate, but it resulted in only a minor reduction of the seabird access window to baited hooks and led to some operational problems during the setting. Artificial baits substantially reduced commercial catches. Moreover, the seabird access to the baited hooks was influenced by the longline configuration, the setting speed and the relative position to the floats and weights. So far, night setting stands out as the best mitigation measure for reducing bycatch levels without compromising target catches in demersal longliners. Ideally, these results should be confirmed in longliners targeting species other than European hake.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Three archaeological sites on California's Channel Islands show that Paleoindians relied heavily on marine resources. The Paleocoastal sites, dated between approximately 12,200 and 11,200 years ago, ...contain numerous stemmed projectile points and crescents associated with a variety of marine and aquatic faunal remains. At site CA-SRI-512 on Santa Rosa Island, Paleocoastal peoples used such tools to capture geese, cormorants, and other birds, along with marine mammals and finfish. At Cardwell Bluffs on San Miguel Island, Paleocoastal peoples collected local chert cobbles, worked them into bifaces and projectile points, and discarded thousands of marine shells. With bifacial technologies similar to those seen in Western Pluvial Lakes Tradition assemblages of western North America, the sites provide evidence for seafaring and island colonization by Paleoindians with a diversified maritime economy.
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Fisheries provide an abundant and predictable food source for many pelagic seabirds through discards, but also pose a major threat to them through bycatch, threatening their populations worldwide. ...The reform of the European Common Fisheries Policy (CFP), which intends to ban discards through the landing obligation of all catches, may force seabirds to seek alternative food sources, such as baited hooks from longlines, increasing bycatch rates. To test this hypothesis we performed a combined analysis of seabird-fishery interactions using as a model Scopoli's shearwaters Calonectris diomedea in the Mediterranean. Tracking data showed that the probability of shearwaters attending longliners increased exponentially with a decreasing density of trawlers. On-board observations and mortality events corroborated this result: the probability of birds attending longliners increased 4% per each trawler leaving the longliner proximity and bird mortality increased tenfold when trawlers were not operating. Therefore, the implementation of the landing obligation in EU waters will likely cause a substantial increase in bycatch rates in longliners, at least in the short-term, due to birds switching from trawlers to longliners. Thus the implementation of the landing obligation must be carefully monitored and counterbalanced with an urgent implementation of bycatch mitigation measures in the longline fleet.
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Marine plastic ingestion by seabirds was first documented in the 1960s, but over 50 years later our understanding about the prevalence, intensity, and subsequent effect of plastic pollution in the ...oceans is still developing. In Canada, systematic assessments using recognized standard protocols began only in the mid-2000s. With marine plastic pollution identified by the United Nations Environmental Program (UNEP) as one of the most critical challenges for the environment, a greater understanding of how plastics affect marine birds in Canada, along with a national strategy, is timely and necessary. To better understand which and how many marine birds are affected by marine debris, we reviewed reports of plastic ingestion and nest incorporation in Canada. Of the 91 marine bird species found in Canadian waters, detailed plastic ingestion data from multiple years and locations are available for only six species. Another 33 species have incidental reports, and we lack any data on dozens more. Future efforts should focus on characterizing the risk of plastic ingestion among understudied species and on continued monitoring of species that are known indicators of plastic pollution internationally and found in multiple regions of Canada to facilitate comparisons at the national and international levels.
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Over the last century, major climate changes and intense human exploitation of natural living resources have occurred in the Southern Ocean, potentially affecting its ecosystems up to top marine ...predators. Fisheries may also directly affect seabirds through bycatch and additional food resources provided by discards. The past 20 yr of research has seen an increasing number of studies investigating the effects of climate change and fisheries activities on Southern Ocean seabirds. Here, we review these studies in order to identify patterns in changes in distribution, phenology, demography and population dynamics in response to changes in climate and fisheries bycatch. Shifts in distribution and breeding phenology were documented in parallel to increases in sea-surface temperatures and changes in sea-ice cover. Above all warm sea-surface temperatures negatively affected demographic parameters, although exceptions were found. Relationships suggest non-linear effects of sea-ice cover on demographic parameters and population dynamics, with optimum sea-ice cover conditions appearing to be the rule. Fishing efforts were mainly negatively related to survival rates, and only for a few species positively related to breeding success. A handful of studies found that chronic mortality of immature birds due to fisheries negatively affected populations. Climate factors and fisheries bycatch may simultaneously affect demographic parameters in a complex way, which can be integrated in population models to project population trajectories under future climate or fisheries scenarios. Needed are studies that integrate other environmental factors, trophic levels, foraging behaviour, climate–fisheries interactions, and the mechanisms underlying phenotypic plasticity, such as some pioneering studies conducted elsewhere.
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Plastic pollution is a ubiquitous global environmental problem. Plastic ingestion by seabirds is an increasing issue even in remote areas, such as the Arctic, yet research and monitoring of plastic ...ingestion in Arctic seabird populations is limited, and there are large knowledge gaps for many geographic regions. There is currently no standard technique for monitoring plastic debris in the Arctic, making it difficult to compare studies and monitor global trends. Here, we review the current state of knowledge of plastic ingestion by seabirds in the Arctic. We analyzed 38 published records that report plastic ingestion by seabirds in the Arctic region. Of the 51 seabird species examined for plastic ingestion in the Arctic, over half have ingested plastic; however, the majority have a limited number of studies, small sample sizes, and (or) data are more than 15 years old. Additionally, the spatial distribution of plastic ingestion reports in the Arctic varies widely, with large knowledge gaps in the northernmost areas of most countries. This indicates that we lack recent information on plastic ingestion for most of the seabird species in the Arctic. Further, less than one-third of studies reference standardized methods from other regions, making it difficult to assess spatial and temporal trends. Long-term monitoring programs should be established in the Arctic to obtain an accurate assessment of plastic ingestion by seabirds in this region.
La pollution par le plastique est un probleme environnemental mondial omnipresent. L’ingestion de plastique par les oiseaux marins est un probleme croissant, meme dans des regions eloignees comme l’Arctique. Pourtant, la recherche et la surveillance de l’ingestion de plastique par la population d’oiseaux marins de l’Arctique sont limitees et il existe des lacunes importantes dans les connaissances pour plusieurs regions geographiques. Il n’y a actuellement aucune technique standard de surveillance des debris de plastique en Arctique, ce qui rend difficiles la comparaison des etudes et le suivi des tendances mondiales. Les auteurs font ici la synthese de l’etat des connaissances sur l’ingestion de plastique par les oiseaux marins en Arctique. Ils ont analyse 38 publications qui rapportent une ingestion de plastique par les oiseaux marins de la region arctique. Sur les 51 especes d’oiseaux marins examinees quant a l’ingestion de plastique en Arctique, plus de la moitie ont ingere du plastique, bien que la majorite de ces publications rapportent un nombre limite d’etudes, de petites tailles d’echantillons ou des donnees datant de plus de 15 ans. Par ailleurs, la distribution spatiale des rapports sur l’ingestion de plastique en Arctique varie grandement, avec d’importantes lacunes dans les connaissances des regions de l’extreme nord dans la plupart des pays. Cela indique que nous manquons d’information recente sur l’ingestion de plastique pour la majorite des especes d’oiseaux marins en Arctique. De plus, moins d’un tiers des etudes font reference a des methodes standardisees d’autres regions, ce qui rend difficile l’evaluation des tendances spatiales et temporelles. Des programmes de surveillance a long terme devraient etre etablis en Arctique afin d’obtenir une evaluation precise de l’ingestion de plastique par les oiseaux marins dans cette region.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
1. Upcoming reform of the European Union (EU) Common Fisheries Policy will be the biggest change in European fisheries management for a generation. A central plank of this reform is a proposed ban on ...discards, to aid the creation of economically and environmentally sustainable fisheries. This, together with a global trend for declining discards, may have unforeseen knock-on consequences for the large number of scavenging seabirds that consume this plentiful subsidy. 2. Discards have shaped many aspects of seabird foraging, distribution and population dynamics. Here, we review these effects and consider the potential for both negative and positive impacts of discard reforms for seabirds, with particular focus on the EU, and propose recommendations for ongoing research and conservation. 3. EU seabird scavengers are dominated by a relatively small number of large generalist taxa. Many of these occur at globally significant numbers within the EU, but may be able to buffer a decline in discards by switching to feed on alternative foods. 4. A discard ban may have negative consequences by creating a food shortage for scavenging birds. Some species may offset this by feeding more on other birds, with potentially negative population-level impacts, or by moving into novel environments. 5. Benefits of a discard ban may be a reduction in seabird bycatch in fishing gears, as well as a reduction in populations of large generalist species that currently dominate some seabird communities. 6. Synthesis and applications. Reform of the Common Fisheries Policy and global discard declines are essential components towards creating sustainable fisheries, but may have both detrimental and beneficial effects on seabird communities. The nature of these impacts is still poorly understood, highlighting the need for detailed long-term seabird monitoring, as well as building resilience into populations through policy measures that incorporate remedial action on major seabird conservation priorities. Research should focus on understanding how seabird foraging, in terms of functional responses and searching behaviour, is influenced by both changing discards and natural fish prey availability, and how they impact upon fitness. It is also essential to link individual-level responses with population-, community- and ecosystemlevel change. Understanding these links is fundamental to ongoing seabird management and conservation, and an ecosystem-based approach to fisheries management.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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