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Social learning can be fundamental to cohesive group living, and schooling fishes have proven ideal test subjects for recent work in this field. For many species, both demographic factors, and inter‐ (and intra‐) generational information exchange are considered vital ingredients in how movement decisions are reached. Yet key information is often missing on the spatial outcomes of such decisions, and questions concerning how migratory traditions are influenced by collective memory, density‐dependent and density‐independent processes remain open. To explore these issues, we focused on Atlantic herring Clupea harengus, a long‐lived, dense‐schooling species of high commercial importance, noted for its unpredictable shifts in winter distribution, and developed a series of Bayesian space‐time occurrence models to investigate wintering dynamics over 23 yr, using point‐referenced fishery and survey records from Icelandic waters. We included covariates reflecting local‐scale environmental factors, temporally‐lagged prey biomass and recent fishing activity, and through an index capturing distributional persistence over time, derived two proxies for spatial memory of past wintering sites. The previous winter's occurrence pattern was a strong predictor of the present pattern, its influence increasing with adult population size. Although the mechanistic underpinnings of this result remain uncertain, we suggest that a ‘wisdom of the crowd’ dynamic may be at play, by which navigational accuracy towards traditional wintering sites improves in larger and/or denser, better synchronized schools. Wintering herring also preferred warmer, fresher, moderately stratified waters of lower velocity, close to hotspots of summer zooplankton biomass, our results indicative of heightened environmental sensitivity in younger cohorts. Incorporating spatiotemporal correlation structure and time‐varying regression coefficients improved model performance, and validation tests on independent observations one‐year ahead illustrate the potential of uniting demographic information and non‐stationary models to quantify both the strength of collective memory in animal groups and its relevance for the spatial management of populations. [ABSTRACT FROM AUTHOR]

Recent advances in the knowledge of the basic requirements to sustain captured lobsters, combined with improved transport links, has seen a dramatic expansion in the sale of liveNephrops norvegicus. In this paper, we describe the effects of storage system type on the health of lobsters held for periods up to three weeks in order to develop an optimal protocol for Icelandic producers for whom logistical challenges have thus far hindered access to the live market.Nephropswere caught by creel and transported to a holding facility in tanks supplied by either a flow-through from a harbour bore or recirculating water via a filtration system, where they were maintained without being fed for a period of three weeks. During this time, lobsters were assessed for haemolymph biochemistry and hepatopancreas composition and health. It was found that lobsters from both systems used storage reserves from the hepatopancreas, showing a progressive decline in hepatopancreatic index, hepatopancreas protein and glycogen.Nephropsfrom the flow-through system also presented indications of considerable health impacts with chronically elevated levels of circulating haemocytes during storage and granuloma plus melanized hepatopancreas tubules after three weeks. [ABSTRACT FROM PUBLISHER]

The intense fishing mortality imposed on Atlantic cod in Icelandic waters during recent decades has resulted in marked changes in stock abundance, as well as in age and size composition. Using a molecular marker known to be under selection ( Pan I) along with a suite of six neutral microsatellite loci, we analysed an archived data set and revealed evidence of distinct temporal changes in the frequencies of genotypes at the Pan I locus among spawning Icelandic cod, collected between 1948 and 2002, a period characterized by high fishing pressure. Concurrently, temporal stability in the composition of the microsatellite loci was established within the same data set. The frequency of the Pan IBB genotype decreased over a period of six decades, concomitant with considerable spatial and technical changes in fishing effort that resulted in the disappearance of older individuals from the fishable stock. Consequently, these changes have likely led to a change in the genotype frequencies at this locus in the spawning stock of Icelandic cod. The study highlights the value of molecular genetic approaches that combine functional and neutral markers examined in the same set of individuals for investigations of the selective effects of harvesting and reiterates the need for an evolutionary dimension to fisheries management. [ABSTRACT FROM AUTHOR]