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Single pass electrofishing method for assessment and monitoring of larval lamprey populationsOur work aims at calibrating and standardizing the single pass protocol of electrofishing to assess and monitor larval lamprey populations, mainly for European populations of sea lamprey (Petromyzon marinus). The method is considered cost-effective and appropriate for use both on the scale of management decisions (from river or watershed to a regional or national scale) and as a routine assessment tool as required by the European Union Habitats Directive. Additionally, the larval surveys may be reconciled with routine electrofishing surveys for fish species, to further reduce costs. In our case, the escapement of larvae from the sampling area when using electrofishing corresponded to 18 % of larvae and 17 % of larval biomass. The general effectiveness of the protocol to determine the density and biomass of age-1 and older larvae in the prospected area was 68 % and 70 %, respectively. Finally, reference categories for density and biomass of larval populations of P. marinus in NW of the Iberian Peninsula are provided.

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George Evelyn Hutchinson is recognised as one of the best limnologists and ecologists of the 20th century, whose contributions have been key for the development of modern ecology and limnology. His most important contributions nclude, concepts, theories and classifications currently used such as, for example, the ecological niche concept, Hutchinson’s paradox and lake classifications. Hutchinson redefined the ecological niche concept based on previous ideas of Grinnell and Elton, suggesting that it should be considered as a hypervolume in the environmental space caused by the ultidimensional response of variables that determine the stability of populations. This new perception of the ecological niche has been fundamental for the development of other investigations in different fields of biology, in particular in ecology, evolution, and biogeography. Furthermore, Hutchinson’s treatise on limnology is considered as the most extensive compilation of limnology. Hutchinson aimed to answer why several species of phytoplankton that compete for the same resources can coexist in an aquatic ecosystem which is usually nutrient deficient (known as the Hutchinson’s paradox). The scientific advances promoted by Hutchinson have inspired many generations of biologists. George Evelyn Hutchinson es reconocido como uno de los mejores limnólogos y ecólogos del siglo XX, cuyas aportaciones han sido cruciales para el desarrollo de la ecología y limnología moderna. Sus más importantes contribuciones incluyen conceptos, teorías y clasificaciones vigentes en la actualidad como, por ejemplo, el concepto de nicho ecológico, la paradoja de Hutchinson y las clasificaciones de lagos. A partir de las ideas de Grinnell y Elton, Hutchinson sugirió que el concepto de nicho ecológico debía considerarse como un hipervolumen en el espacio ambiental originado por la respuesta multidimensional de las variables que determinan la estabilidad de las poblaciones. Esta nueva percepción del nicho ecológico ha sido fundamental para el desarrollo de otras investigaciones en diferentes campos de la biología, particularmente en la ecología, la evolución y la biogeografía. Por otro lado, el tratado de limnología realizado por Hutchinson es considerado como la recopilación más extensa de la limnología. Hutchinson intentó dar respuesta a por qué varias especies del fitoplancton que compiten por los mismos recursos pueden coexistir en un ecosistema acuático que por naturaleza suele ser deficiente en nutrientes (conocido como la paradoja de Hutchinson). Los avances científicos promovidos por Hutchinson han servido de fuente de inspiración a muchas generaciones de biólogos.

Accidental introduction of anadromous sea lampreys (Petromyzon marinus Linnaeus, 1758) into a European reservoirLandlocked populations of sea lamprey (Petromyzon marinus) cause tremendous damage to native fish species: nevertheless, none of these populations have been described in Europe. The first record of an introduction of anadromous P. marinus into a reservoir in Europe (Portodemouros, NW Spain) is described. Data suggest that this landlocked population was not successful and did not settle in the area because the haematophagous feeding phase was not viable. This agrees with the difficult transition from an anadromous haematophagous life history to a freshwater haematophagous life history. However, the settlement of stable populations of sea lamprey in lakes or reservoirs with more appropriate host populations cannot be discarded.