An isolated partial right dentary (BAS D.515.2) collected by the British Antarctic Survey prompted a re-evaluation of gadiform remains from the La Meseta Formation (conventionally middle Eocene) of Isla Marambio (Seymour Island), Antarctic Peninsula. Modern gadiforms (hakes and cods) range from the Arctic to Antarctic, inhabiting deep sea benthic, shore, estuarine, and freshwater environments. Based on a fossil record primarily composed of otoliths, they are known to extend back to the Eocene and Oligocene. The new specimen was recovered from the fossil penguin locality D.515. It is characterized by a single row of sharp, ankylosed teeth set upon robust bony pedestals. The surface anterior to the mental foramen exhibits ascending and descending ridges with slightly rugose texture. The ascending ridge is fractured, but partially covers the lateral aspect of the tooth row. BAS D.515.2 is unlike the dentary of macrourid gadiforms, also recovered from the Eocene of Antarctica. BAS D.515.2 preserves several features similar to previously published accounts of the gadiform “†Mesetaichthys” from Isla Marambio. These specimens are probably the same taxon and their combined character suite indicates it is a member of Merluccidae. Thus, these are the only non-otolithic skeletal specimens of an Eocene hake known outside of the London Clay's †Rhinocephalus.

The Chilean hake (Merluccius gayi gayi) is the predominant groundfishspecies inhabiting the southern Humboldt, mainly from Coquimbo (29° S) to Puerto Montt(42° S). At present there is only limited knowledge on the spatial distribution ofjuveniles of this species, particularly concerning its dependence on key physicalcharacteristics. On the basis of annual surveys carried out during austral winters from1997 to 2006, changes in the presence of juveniles were studied using Generalized AdditiveModel techniques. Temporal factors and spatial effects were more important than singlephysical variables in explaining the presence of juvenile hake (<34 cm totallength). Juvenile hake had a preference for shallower waters. Although salinity and oxygenwere significant, their contribution was marginal. Juvenile hake seem to prefer shallowoxygenated waters, but the nonlinear relationships and partial secondary peaks detected insalinity and oxygen probably only reflected the influence of three water masses found inthe winter habitat. Endogenous factors could be more important in determining temporal andspatial changes in the proportion of juvenile hake. An important change in the presence ofjuveniles has occurred since 2004, coinciding with a significant decline in biomass ofadult hake. It is postulated that cannibalism pressure from adults has probably declinedand that spatial and temporal changes in the presence of juvenile hake seem to be moreassociated with fishery-induced demographic effects.

Catch rates (kg hour−1) of horse mackerel (Trachurus trachurus), blue whiting (Micromesistius poutassou) and hake (Merluccius merluccius) from a series of 22 groundfish surveys conducted off Portugal between 1989 and 1999 were analysed using integrated logistic and gamma Generalized Linear Models (GLM). This methodology deals with the large amount of zeros in survey data matrices by modelling the probability of catch and the amount of positive catch separately, and then integrating the two sub-models into a single catch rate model of abundance. Among the explanatory variables included in the models, the geographic areas occupied by fish assemblages, i.e., groups of persistent co-occurring species, explained most of the variability observed for horse mackerel and blue whiting, while depth was the most important factor for hake. Because of hake's ubiquity on the Portuguese margin, models for this species were less parsimonious and explained a lower proportion of total variability compared with the other species. The abundance of horse mackerel is much higher in the winter and reduces with depth. Blue whiting and horse mackerel exhibited opposite trends in abundance from 1991 to 1994, with the latter species presenting a higher abundance throughout this period. No clear temporal trends of abundance were detected for hake. The effect of trawling hour in models suggested that horse mackerel and blue whiting exhibit vertical migrations, staying close to the bottom by day, when abundance is higher. The current approach proved to cope well with sparse catch data matrices and brought out novel information on the ecology of fish species in the Portuguese continental margin by successfully integrating environmental information into the analysis of fish abundance.

Mediterranean demersal fisheries have experienced an ongoing decline in catches over the past 20 years as a result of excessive increases in effort caused both by growth in trawler engine power and by rapid technological advances in fish finding and fishing technology. This has led to an overexploitation of these resources. An increasing share of the catches consists of immature individuals. This study was undertaken to test a sorting grid with a bar spacing of 20 mm as a means of excluding juveniles in the commercial hake (Merluccius merluccius) fishery in the Catalan Sea, western Mediterranean. The grid was placed in the extension section of the gear 5 m in front of a cod-end. Divided cod-end design was used to collect the escapees and target species. The mean selection length (L50) of the ten hauls was 14.2 ± 0.7 cm SE, with a selection range of 7.3 cm ± 0.4 SE. The biomass of hake under L50 that escaped through the grid represented 50.1% ± 6.7 SE of the total hake biomass. These results are promising and indicate that a sorting grid can be used in excluding young hake. This was a first step toward implementation of sorting grids in commercial trawl gears as means of avoiding unwanted catches of small individuals in the hake fisheries in the Mediterranean Sea. Further trials are required to improve the sorting efficiency of the grid.