The World Conference on Stock Assessment Methods (July 2013) included a workshop on testing assessment methods through simulations. The exercise was made up of two steps applied to datasets from 14 representative fish stocks from around the world.Step 1 involved applying stock assessments to datasets with varying degrees of effort dedicated to optimizing fit.Step 2 was applied to a subset of the stocks and involved characteristics of given model fits being used to generate pseudo-data with error. These pseudo-data were then provided to assessment modellers and fits to the pseudo-data provided consistency checks within (self-tests) and among (cross-tests) assessment models. Although trends in biomass were often similar across models, the scaling of absolute biomass was not consistent across models. Similar types of models tended to perform similarly (e.g. age based or production models). Self-testing and cross-testing of models are a useful diagnostic approach, and suggested that estimates in the most recent years of time-series were the least robust. Results from the simulation exercise provide a basis for guidance on future large-scale simulation experiments and demonstrate the need for strategic investments in the evaluation and development of stock assessment methods.

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Discarding is considered by many as an important problem in world fisheries. In many regions, data collection onboard commercial vessels has intensified, and the understanding of both human and ecological drivers of discards is improving quickly. Discarding patterns vary widely across regions, fisheries, gears, and species. Fishers' responses to regulations and markets explain these complex patterns, on top of resource availability partly driven by environmental fluctuations. This expanded knowledge base provides an appropriate basis for discussing the discard mitigation measures proposed in various settings. In September 2012, a theme session was convened at the ICES Annual Science Conference in Bergen, Norway, to discuss these issues. This themed set of articles includes several of the studies presented at the theme session. Owing to the wide diversity of drivers and reasons for discarding, no single management measure or even framework is expected to address the issue. Rather, discard mitigation measures need to be tailored to each particular fishery, or even species within a fishery, and the effectiveness of solutions is greatest when they are used in combination with other approaches. Bottom-up approaches to bycatch and discard management, which involve incentive-based solutions to bycatch problems, were agreed to be the most promising.

There are seven species of skates (family Rajidae) found along the East Coast of the USA. All seven species are currently managed by the New England Fisheries Management Council as a single management complex extending from the Gulf of Maine to Cape Hatteras. The objective of the management plan is to ensure the long‐term sustainability of fishing for each species via a trip limit approach. Two species are harvested in two distinct commercial fisheries. Northeast Fisheries Science Center trawl survey data and published literature were examined to investigate differences between the individual species in the skate complex. Each species exhibited a unique thermal and geographic range in addition to vital life history traits (e.g., age at maturity, longevity, and maximum size). Thorny Skate Amblyraja radiata and Smooth Skate Malacoraja senta have narrow thermal ranges and maintain a more northern distribution. Barndoor Skate Dipturus laevis have a moderate thermal habitat. Little Skate Leucoraja erinacea and Winter Skate L. ocellata have broad thermal ranges and are distributed throughout the management area. Limited inferences can be made about the thermal preferences of Clearnose Skate Raja eglanteria without data from south of Cape Hatteras, but they appear to have a broad thermal range within the management area. Rosette Skate L. garmani have a narrow thermal range and tend to be found in the deep offshore mid‐Atlantic region. The validity of managing multiple distinct species in a complex is questioned. This example shows that a mixed‐stock management strategy may be inadequate to meet the sustainability needs of each species and the associated fisheries. A management strategy focused on individual species may lead to a more efficient harvest of targeted species while allowing for the rebuilding of overfished species. Received November 8, 2011; accepted December 27, 2012

Multispecies models have existed in a fisheries context since at least the 1970s, but despite much exploration, advancement, and consideration of multispecies models, there remain limited examples of their operational use in fishery management. Given that species and fleet interactions are inherently multispecies problems and the push towards ecosystem-based fisheries management, the lack of more regular operational use is both surprising and compelling. We identify impediments hampering the regular operational use of multispecies models and provide recommendations to address those impediments. These recommendations are: (1) engage stakeholders and managers early and often; (2) improve messaging and communication about the various uses of multispecies models; (3) move forward with multispecies management under current authorities while exploring more inclusive governance structures and flexible decision-making frameworks for handling tradeoffs; (4) evaluate when a multispecies modelling approach may be more appropriate; (5) tailor the multispecies model to a clearly defined purpose; (6) develop interdisciplinary solutions to promoting multispecies model applications; (7) make guidelines available for multispecies model review and application; and (8) ensure code and models are well documented and reproducible. These recommendations draw from a global assemblage of subject matter experts who participated in a workshop entitled “Multispecies Modeling Applications in Fisheries Management”.