Year class mortality, abundance and yield-per-recruit of yellowfin tuna in the eastern Pacific Ocean, 1954-1959

ENGLISH: One primary duty of the Inter-American Tropical Tuna Commission is to estimate the maximum sustainable catches of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis), and to investigate and recommend proposals to maintain the stocks at levels which will permit these catches to be obtained. To do this, there is required some means of predicting yields relative to fishing intensity. . . The age composition of catch, and growth rate of yellowfin tuna for recent years have now been estimated (Hennemuth, 1961). In this paper, relative abundance at age of yellowfin tuna shall be estimated -and used, in turn, to estimate total mortality rate. Yield-per-recruit calculations, based on Beverton and Holt's (1957) simple equation, will be presented to compare present utilization with theoretical maxima under varying levels of fishing mortality and different ages at first capture. SPANISH: Uno de los principales deberes de la Comisión Interamericana del Atún Tropical es estimar las pescas máximas sostenibles de los atunes aleta amarilla (Neothunnus macropterus) y barrilete (Katsuwonus pelamis) , así como estudiar y recomendar proposiciones para mantener los stocks a niveles que permitan obtener estas pescas. Para lograr este propósito se requieren algunos medios que permitan predecir el rendimiento en relación con la intensidad de la pesca. . La composición de edades de la pesca y la tasa de crecimiento del atún aleta amarilla en años recientes han sido estimadas ahora (Hennemuth, 1961). En este trabajo, la abundancia relativa a una edad dada de esta especie será estimada y usada, a su vez, para estimar la tasa de mortalidad total. Los cálculos del rendimiento por recluta, basados en la ecuación simple de Beverton y Holt (1957), serán presentados para comparar la utilización actual con los máximos teóricos bajo valores variables de mortalidad por la pesca y a diferentes edades a la primera captura.

Rückwürfe in den Fischereien unter deutscher Flagge: Ergebnisse aus 6 Jahren Datenerhebungsprogramm am Institut für Seefischerei

Since 2002 Germany is obliged to collect fishery data to support the European Common Fishery Policy. Sampling of the com-mercial fishery under German flag is one duty within the EU fisheries data collection programme. During the past 6 years, 148 fishing trips were sampled by scientific observers onboard commercial fishing vessels to collect data on catch composi-tions with special emphasis on the proportions of landed and discarded fish. The results show that the proportion of discard is depending on the fishery. Highest discard rates were observed on beam trawl fishing trips. At the level of individual fishing trips, discard rates varied extremely within a fishery segment. Highest variations were found in the beam and bottom otter trawl fishery. In contrast, the discard rates in high-seas fisheries were low.

Report of the Inter-American Tropical Tuna Commission for the year 1962

ENGLISH: The Inter-American Tropical Tuna Commission, pursuant to the provisions of the Convention, has the duty of collecting and interpreting factual information to facilitate maintaining the populations of tunas, and of tuna baitfishes, supporting the fisheries pursued by nationals of its Member Governments in the Eastern Pacific Ocean, at levels which will permit maximum sustainable average harvests year after year. This requires a wide variety of research into the biology, life history, ecology and population dynamics of the several species, and investigations into the effects of both natural factors and fishing activity on their abundance and on the harvests they can sustain. The research is conducted by a permanent, internationally recruited scientific staff, employed directly by the Commission, selected on the basis of professional competence by the Director of Investigations. SPANISH: La Comisión Interan1ericana del Atún Tropical, de informidad con las disposiciones de la Convención, tiene el deber de recolectar e interpretar la información que facilite el mantenimiento de las poblaciones del atún y de los peces de carnada que sirven para la pesca de este, sosteniendo las pesquerías a que se dedican los habitantes de sus Gobiernos Miembros en el Océano Pacifico Oriental, a niveles ,de abundancia que permitan un promedio máximo sostenible de cosechas ano tras ano. Esto requiere una amplia variedad de investigaciones dentro de la biología, historia natural, ecología y dinámica de las poblaciones de diversas especies, y sabre los efectos, tanto de los factores naturales como de la actividad pesquera, en la abundancia de las mismas y en el rendimiento que puedan dar. La investigación es conducida por un grupo científico permanente, cuyos miembros son reclutados internacionalmente empleados directamente por la Comisión, una vez que han sido seleccionados sobre la base de su competencia profesional, por el Director de Investigaciones. (PDF contains 149 pages.)

My Days on the Albatross

Navigation and surveying formed a connecting link, as it were, between what was getting to be called the “Old Navy” and what was soon to take shape as a “New Navy.” Seamanship, as an art of special character, was beginning to change its form with the passing of sail power and its supersession by the steam engine; while requiring in its new form no less ability and practiced judgment in the handling of large ships, it offered a diminished field for expertness in craft of only moderate size and speed among officers doing simple watch duty not in company with other ships; and, therefore, it was threatened with a materially lessened regard.