Classifying movement behaviour of marine predators in relation to anthropogenic activity and environmental conditions is important to guide marine conservation. We studied the relationship between grey seal ( Halichoerus grypus ) behaviour and environmental variability in the southwestern Baltic Sea where seal-fishery conflicts are increasing. We used multiple environmental covariates and proximity to active fishing nets within a multivariate hidden Markov model (HMM) to quantify changes in movement behaviour of grey seals while at sea. Dive depth, dive duration, surface duration, horizontal displacement, and turning angle were used to identify travelling, resting and foraging states. The likelihood of seals foraging increased in deeper, colder, more saline waters, which are sites with increased primary productivity and possibly prey densities. Proximity to active fishing net also had a pronounced effect on state occupancy. The probability of seals foraging was highest <5 km from active fishing nets (51%) and decreased as distance to nets increased. However, seals used sites <5 km from active fishing nets only 3% of their time at sea highlighting an important temporal dimension in seal-fishery interactions. By coupling high-resolution oceanographic, fisheries, and grey seal movement data, our study provides a scientific basis for designing management strategies that satisfy ecological and socioeconomic demands on marine ecosystems.

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The Greifswalder Bodden (GWB) is considered to be the most important spawning and nursery area for the western Baltic spring-spawning herring. However, the biotic and abiotic reasons for this are still unclear. Consequently, we investigated larval growth conditions in the GWB and in the Kiel Canal (KC), another nursery and spawning area of Baltic herring. We investigated prey quantity and quality [copepod abundance and essential fatty acid (EFA) concentration] as well as biochemically derived growth rates and fatty acid content of larval herring in spring 2011. A significant correlation between larval growth and larval EFA concentration could be observed in the GWB. The highest growth rates and EFA concentrations in the larval herring coincided with high food quality. Compensating effects of food quality on food quantity and vice versa could be observed in both the GWB and the KC. While larval growth rates in the KC were high early in the season, highest growth rates in the GWB were achieved late in the season. In conclusion, neither area was superior to the other, indicating similar growth conditions for larval herring within the region.

Hammer, C., von Dorrien, C., Hopkins, C. C. E., Köster, F. W., Nilssen, E. M., St John, M., and Wilson, D. C. 2010. Framework of stock-recovery strategies: analyses of factors affecting success and failure. – ICES Journal of Marine Science, 67: 1849–1855. 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.

was investigated. The larval distribution in the channel was analysed based on 187 samples from 9 stations collected from November 1993 to May 1994. 50 of these samples were used to investigate the taxonomic composition. Larval densities varied between 0 and 376 ind. per 50 m³. Seasonal and geographical patterns were found. Both in dry and rainy season larval abundance was low at the inner channel. Except a few hauls, most samples did not exceed densities of 25 or 45 ind./50 m³, respectively. High concentrations beyond 100 ind. per 50 m³ were found at station 2, 3 and once at station 8 in the northern part and at station 7 in the southern part of the channel. Engraulidae larvae and different types of Gobiidae were the dominant groups in the channel. These two families reached almost 76% of the whole ichthyoplankton in the catches. They are followed by Achiridae, Clupeidae, Terapontidae, Sciaenidae, Tetraodontoidei, Carangidae, Syngnathidae, Cottidae (?) and Blennioidei (summing up to 95% of the caught fish larvae in the channel). Nearly all groups are found as adults in the channel. Only five families are represented exclusively by larvae: Achiriidae, Cottidae, Terapontidae, Exocoetidae and Ephippidae. From the latter, only Exocoetidae form an oceanic group. Based on the taxa composition, it is assumed, that the importance of the estuary as nursery ground for shelf and oceanic fish is low. Key words: Ichthyoplankton; estuary; larval distribution;