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Introduction 32Results of reviewed mitigation methods 35Mitigation methods relevant to multiple fisheries 35Offal and discard management 35 Area/seasonal closures 36 Longlining 36 Underwater setting devices 36 Funnel (lining tube) 36 Chute 37 AbstractWith an increasing number of seabird species, particularly albatross and petrels, becoming threatened, a reduction of fishery impacts on these species is essential for their future survival. Here, mitigation methods to reduce and avoid seabird bycatch are assessed in terms of their ability to reduce bycatch rates and their economic viability for longline, trawl and gillnet fisheries worldwide. Factors influencing the appropriateness and effectiveness of a mitigation device include the fishery, vessel, location, seabird assemblage present and season of year. As yet, there is no single magic solution to reduce or eliminate seabird bycatch across all fisheries: a combination of measures is required, and even within a fishery there is likely to be refinement of techniques by individual vessels in order to maximize their effectiveness at reducing seabird bycatch. In longline demersal and pelagic fisheries, a minimum requirement of line weighting that achieves hook sink rates minimizing seabird bycatch rates should be tailored with a combination of strategic offal and discard management, bird-scaring lines (BSLs) and night-setting, particulary in Southern Hemisphere fisheries. Urgent investigation is needed into more effective measures at reducing seabird interactions with trawl nets and gill nets. In trawl fisheries, a combination of offal and discard management, the banning of net monitoring cables, paired BSLs, and a reduction in the time the net is on or near the surface are likely to be the most effective in reducing seabird interactions with the warp cables and net. Few seabird bycatch reduction methods have been developed for gillnet fisheries, although increasing the visibility of the net has been shown to reduce seabird bycatch. Further studies are required to determine the efficacy of this technique and its influence on target species catch rates.

The current primary threats to biodiversity on a global scale are species invasions and habitat modification. Management of vulnerable populations often involves a lengthy sequence of 1) research to identify threats and recommend management strategies, 2) active management, and 3) results monitoring to assess effectiveness of management. The last mainland population of the large, endemic New Zealand skink (Whitaker's skink [Cyclodina whitakeri]) provides an opportunity to test this process in a system where the synergistic effects between invasive species (introduced rodents and grasses) have predicted outcomes. A low abundance of Whitaker's skink at the Pukerua Bay Scientific Reserve in the 1980s prompted management recommendations to remove grazing stock and revegetate the site to simultaneously restore habitat and provide protection against introduced mammalian predators. Since Whitaker's skink have low detectability, it was recommended that sympatric copper skink (C. aenea) be used an indicator species of management effectiveness. Grazing stock were removed in 1987, but efforts to revegetate the site were ineffective. Long‐term monitoring (1984‐2006) of the Whitaker's skink population and 4 other sympatric lizard species within a 336‐m2 area at the site resulted in 1,693 lizard captures over 7,597 trap days. Whitaker's skink represented 2.8% of all captures in 1984‐1988, but declined relative to other species to represent only 0.2% of captures in 2000‐2006 (representing 2 individuals). Congeneric copper skink showed a similar decline with capture rates also approaching zero by 2006. Removing grazing stock did not result in an increased abundance of Whitaker's skink or copper skink through improved habitat quality, as was intended by the management recommendation. Instead, reduced grazing has allowed introduced seeding grasses to proliferate, which may have led to periodic rodent irruptions, supporting a guild of introduced mammalian predators and depleting populations of Whitaker's skink and copper skink. In this instance, attempted protection may have driven a vulnerable population towards extinction. We recommend investigating the feasibility of constructing a mammal‐proof fence around the core Whitaker's skink habitat, as the last remaining management option to salvage the population.

Introduction 409Cable-related mortality 409Net-related mortality 410Best practice 410 Methods and scope 410Results of reviewed mitigation methods 411Reducing vessel attractiveness -discharge management 411Presence of offal and discards 411 Management of offal and discards 412Warp cable protection 412 Bird-scaring lines 412 Cones vs. buoys on paired BSLs 413 Warp scarers 414 Bird bafflers 415 Cones on warp cables 416 Net protection/modification 416 Net binding 416 Mesh size 416 Abstract This paper provides an update on an earlier review [Fish & Fisheries 8 (2007) 31] of mitigation methods used to reduce seabird by-catch in trawl fisheries. Interactions of seabirds with trawl vessels fall into two broad categories: those focused on the trawl warps and those focused around trawl nets.For reducing seabird strikes on trawl warps, the use of bird-scaring lines has been proved to be the most effective mitigation device in the trawl fisheries in which comparative studies have been undertaken. However, the retention or strategic management of fish waste (offal and discards) is recommended as the most effective primary measure for by-catch reduction, and as such should be viewed as the best long-term solution to reducing seabird by-catch in trawl fisheries. Coincident with effective fish waste management, measures such as cleaning the net prior to shooting and reducing the time the net is on the surface should be viewed as best practice measures and incorporated into normal fishing activities. While a number of methods have been trialled to reduce the incidence of warp strikes, there continues to be the need for more work on effective measures for reducing interactions of seabirds with the trawl net.