Framework of stock-recovery strategies: analyses of factors affecting success and failure

The EU FP6 UNCOVER project was aimed at producing a rational scientific basis for developing recovery strategies for some ecologically and socio-economically important fish stocks/fisheries in European seas. The immediate objectives were to identify changes experienced during stock depletion/collapses, to understand prospects for recovery, to enhance the scientific understanding of the mechanisms of recovery, and to formulate recommendations on how best to implement long-term management/recovery plans. We extended an earlier analysis conducted within the project of 13 performance criteria in relation to the recovery of more than 30 fish stocks/fisheries worldwide by multivariate exploratory analysis (canonical correspondence analysis), followed by model building [discriminant analysis (DA)] to quantify the relative importance of key performance criteria, singly or combined. Using the existing database, DA indicated that the four best additive predictors of successful recovery were "rapid reduction in fishing mortality", "environmental conditions during the recovery period", "life-history characteristics" of the target stock, and "management performance criteria". The model classified the status "recovered" and "non-recovered" assigned originally with nearly 100% accuracy

α-decay spectroscopy of the chain 179Tlg→175Aug→171Irg→167Rem^{179}Tl^{g}→^{175}Au^{g}→^{171}Ir^{g}→^{167}Re^{m}

Detailed α-decay studies of 179Tlg and its daughter products 175Aug and 171Irg were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the α-decay properties of 175Aug was performed as follows: Eα = 6433(4) keV, T1/2 = 207(7) ms, and α-decay branching ratio 90(7)%. First determination of the α-decay branching ratios for 179Tlg and 171Irg was also made: bα(179Tlg) = 60(2)% and bα(171Irg) = 15(2)%. The spins of the ground states in 175Au and 171Ir are established as 1/2+

The ecophysiology of Sprattus sprattus in the Baltic and North Seas

The European sprat (Sprattus sprattus) was a main target species of the German GLOBEC program that investigated the trophodynamic structure and function of the Baltic and North Seas under the influence of physical forcing. This review summarizes literature on the ecophysiology of sprat with an emphasis on describing how environmental factors influence the life-history strategy of this small pelagic fish. Ontogenetic changes in feeding and growth, and the impacts of abiotic and biotic factors on vital rates are discussed with particular emphasis on the role of temperature as a constraint to life-history scheduling of this species in the Baltic Sea. A combination of field and laboratory data suggests that optimal thermal windows for growth and survival change during early life and are wider for eggs (5–17 °C) than in young (8- to 12-mm) early feeding larvae (5–12 °C). As larvae become able to successfully capture larger prey, thermal windows expand to include warmer waters. For example, 12- to 16-mm larvae can grow well at 16 °C and larger, transitional-larvae and early juveniles display the highest rates of feeding and growth at ∼18–22 °C. Gaps in knowledge are identified including the need for additional laboratory studies on the physiology and behavior of larvae (studies that will be particularly critical for biophysical modeling activities) and research addressing the role of overwinter survival as a factor shaping phenology and setting limits on the productivity of this species in areas located at the northern limits of its latitudinal range (such as the Baltic Sea). Based on stage- and temperature-specific mortality and growth potential of early life stages, our analysis suggests that young-of-the year sprat would benefit from inhabiting warmer, near-shore environments rather than the deeper-water spawning grounds such as the Bornholm Basin (central Baltic Sea). Utilization of warmer, nearshore waters (or a general increase in Baltic Sea temperatures) is expected to accelerate growth rates but also enhance the possibility for density-dependent regulation of recruitment (e.g., top-down control of zooplankton resources) acting during the late-larval and juvenile stages, particularly when sprat stocks are at high levels. Highlights ► Field, laboratory and modeling research on the ecophysiology of all sprat life stages is summarized. ► Environmental factors influencing growth and survival are revealed. ► Ontogenetic changes in thermal tolerance and prey requirements constrain life cycle scheduling. ► Gaps in knowledge are identified and future research efforts recommended on sprat recruitment dynamics. ► Exploring seasonal energy allocation will allow a mechanistic understanding of climate impacts