The European eel ( Anguilla anguilla L.) has a catadromous life cycle, with a single panmictic population that colonises continental Europe and northern Africa yet migrates 5000 to 9000 km to spawn in the Atlantic Ocean. It is unknown how this continental migration is organised so individual eels arrive in time for spawning with conspecifics. This meta‐analysis combined tracking data from 18 water bodies in freshwater and tran...

As a result of long‐term climate change, regions of the ocean with low oxygen concentrations are predicted to occur more frequently and persist for longer periods of time in the future. When low levels of oxygen are present, this places additional pressure on marine organisms to meet their metabolic requirements, with implications for growth, feeding and reproduction. Extensive research has been carried out on the effects of a...

A radio frequency identification ( RFID ) antenna system, build into a sledge that can be towed behind a vessel like a trawl and thereby has the potential to detect the position of a passive inductor technology ( PIT )‐tagged fish in a wide variety of habitats, is presented. By scanning for hatchery‐reared PIT ‐tagged turbot Psetta maxima released into a natural habitat, the performance of the system was compared to a standard...

Concern has increased in recent years over the sustainability of anguillid populations worldwide in the face of sustained consumer demand. This is as true of the more numerous tropical species as it is for the better known temperate species. There are, however, critical gaps in knowledge of anguillid biology and ecology, and these hold back measures designed to conserve and enhance anguillid populations, including aquaculture....

The application of data storage tags bears the potential for a quantum leap in the research on fish migrations, because not only first‐capture and recapture positions are known, but at least theoretically, the migration path during the period at large can be reconstructed. Position, however, cannot be measured directly but has to be estimated using the available data on light, temperature, pressure and salinity. The reconstruc...

Anguillid eels Anguilla spp. evolved between 20 and 40 million years ago and possess a number of remarkable migratory traits that have fascinated scientists for millennia. Despite centuries of effort, the spawning areas and migrations are known only for a few species. Even for these species, information on migratory behaviour is remarkably sketchy. The latest knowledge on the requirements for successful migration and field dat...

Over 200 pelagic juvenile cod Gadus morhua and whiting Merlangius merlangus were sampled in spring 2001 at stations inside and outside a frontal region close to the Norwegian Trench, and their stomach contents analysed in the context of zooplankton samples taken at the same time and same locations. Merlangius merlangus juveniles appeared to feed on a diverse zooplankton community, whereas G. morhua juveniles appeared to prefer...

The effect of electronic data storage tags (DSTs) on the growth of cod Gadus morhua was evaluated in laboratory and field experiments. In the first laboratory experiment, large DSTs (60 × 18 mm, 3 g in water ) attached externally for 3 months did not have any effect ( anova , P > 0·05) on the growth of adult cod (mean ± s . d . 65 ± 4·5 cm total length) relative to untagged adult cod. In a second experiment, small DSTs (34 × 1...

The territorial and foraging behaviour of two Red Sea butterflyfish species was studied at three sites in the Gulf of Aqaba. Chaetodon austricaus , a generalist corallivore that exploited evenly distributed food resources, maintained exclusive pair territories. Individuals fed by grazing for brief periods on a coral colony before moving to the next. In contrast, C. trifascialis , a specialist corallivore that exploited patchil...

Fish behaviour varies considerably in response to changes in environmental and biological conditions. Cod ( Gadus morhua ) is not a homeothermic species and recent research has suggested that the recruitment and distribution of cod stocks may be influenced by temperature. Concerns have therefore been raised about the potential effect of climate change on stocks that are already at the southern limits of their range. We used da...