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Abstract: This paper addresses how large aggregations of fish found on many seamounts are sustained. We used a generic seamount ecosystem model from the Northeast Atlantic to examine the impact of a potential increase of local primary production on higher trophic levels, to quantify the immigration of allochthonous micronekton that would be required to maintain a “typical” seamount community, and to quantify if the necessary immigration ratios could be supported by local oceanographic conditions. Our simulation predictions indicate a lack of autochthonous resources in the system to support large amounts of seamount aggregating fish. In other words, autochthonous seamount production may be responsible for sustaining only a small amount of its total biomass. Additionally, our study supports the idea that enhancement of primary productivity also cannot sustain large aggregations of seamount fish. Our seamount model, which took into account high abundances of fish, marine mammals, seabirds and tuna, required a total immigration of allochthonous micronekton of 95.2tkm−2 yr−1 less than the potential available biomass after considering the immigration of prey based upon average current velocities and prey standing stocks in oceanic waters. Our model predicted that the horizontal flux of prey would be sufficient to sustain the rich communities living on seamounts. [Copyright &y& Elsevier]

Ecosystem-based fisheries management (EBFM) is a globally mandated approach with the intention to jointly address ecological and human (social-cultural, economic and institutional) dimensions. Indicators to measure performance against objectives have been suggested, tested, and refined but with a strong bias towards ecological indicators. In this paper, current use and application of indicators related to the human dimension in EBFM research and ecosystem models are analysed. It is found that compared to ecological counterparts, few indicators related to the human dimension are commonly associated with EBFM, and they mainly report on economic objectives related to fisheries. Similarly, in the most common ecosystem models, economic indicators are the most frequently used related to the human dimension, both in terms of model outputs and inputs. The prospect is small that indicators mainly related to profitable fishing economy are able to report on meeting the broad range of EBFM objectives and to successfully evaluate progress in achieving EBFM goals. To fully conform with EBFM principles, it is necessary to recognise that ecological and human indicators are inter-dependent. Moreover, the end-to-end ecosystem models used in EBFM will need to be further developed to allow a fuller spectrum of social-cultural, institutional, and economic objectives to be reported against. • Ecosystem-based fisheries management (EBFM) includes ecological and human objectives. • Research focus has been on mainly ecological EBFM indicators. • Human indicators and to which EBFM objectives they relate were reviewed. • Only a few indicators were commonly used, mainly related to fishing economy. • It is important to appropriate address all dimensions in operationalizing EBFM. [ABSTRACT FROM AUTHOR]

Longline fisheries have expanded throughout the world''s oceans since major commercial distant-water pelagic fleets began fishing for tuna and tuna-like species in the early 1950s. Along with the more recent development and expansion of demersal longline fleets for species such as Patagonian toothfish, these vessels are a major source of mortality to several species of seabird. Vessels can set many thousands of baited hooks in a day across many kilometres of water. These waters are often used as foraging areas by wide-ranging seabirds. Attracted by baits and offal, the birds can be caught on the baited hooks and subsequently drown. To provide a greater understanding of the potential impact of the Southern Ocean''s longline fleets on seabird populations, this paper describes the trends in longline effort of the major pelagic and demersal fisheries in southern waters. The total reported effort from all longline fleets south of 30°S has been well over 250 million hooks per year since the early 1990s. However the spatial and temporal distribution of this effort has not been constant. While effort from the Japanese pelagic distant-water longline fleet declined through the 1990s, the Taiwanese fleet expanded dramatically. Likewise demersal fishing for toothfish increased markedly during the mid-1990s. These fisheries, along with substantial illegal longline fisheries, may be placing the long-term viability of many Southern Ocean species of seabird in jeopardy. [Copyright &y& Elsevier]