Robert Klaus Bauer

• PhD
• Research Affiliate at University of Hawaiʻi at Mānoa

Scalloped hammerhead sharks Sphyrna lewini are a circumglobal species found in tropical and subtropical waters. Globally, populations of S. lewini have undergone dramatic declines in recent decades, and 4 of 6 distinct population segments are at risk of extinction and listed under the United States Endangered Species Act. Despite this, limited data...

The silky shark Carcharhinus falciformis regularly associates with floating objects in the open ocean, resulting in relatively high levels of bycatch in industrial tuna purse seine fisheries using drifting fish aggregating devices (FADs). This bycatch has contributed to concerns regarding the sustainability of this fishery and its impact on silky s...

• Marine protected areas (MPAs) are becoming a widely used tool for the conservation of biodiversity and for fishery management; however, most of these areas are designed without prior knowledge of the basic ecological aspects of the species that they are trying to protect. • This study investigated the movement of two top predators: the Galapagos...

Atlantic bluefin tuna (Thunnus thynnus) (ABFT) frequently engage in surface basking and foraging behaviour that makes them detectable from afar. This behaviour is utilized for the development of fisheries-independent abundance indices based on aerial surveys, although changes in the surface-feeding dynamics of ABFT are not yet accounted for. We inv...

Identified were suitable dosages of tetracycline hydrochloride (TET) in three single treatments and three combined treatments of TET with 2 mg/kg strontium chloride (STR) in wild western Baltic cod (Gadus morhua), in terms of (a) obtainable mark qualities (visibility of fluorescent bands), (b) growth assessment, and (c) induced mortality rates. Iso...

Sardine Sardina pilchardus, anchovy Engraulis encrasicolus and European hake Merluccius merluccius represent a significant part of the commercial landings in the Gulf of Lions (northwestern Mediterranean Sea). However, their stocks have shown severe declines during the last decades due to fishing pressure and/or environmental changes. The aim of th...

Biologging has become an important tool for investigating the behaviour of animals within their physical environment. As leading pioneers in marine biologging, our scientists at MARine Biodiversity, Exploitation and Conservation (MARBEC), a joint research unit by IRD, IFREMER, CNRS and the Université de Montpellier, in France, developed numerous ap...

Time series of depth data, obtained for 6 oceanic whitetip sharks (Carcharhinus longimanus) tagged with pop-up satellite archival tags, were analyzed in detail. The aim was to improve our knowledge of the vertical behavior of this species. Individuals were tagged in the Atlantic Ocean (n=5) and In- dian Ocean (n=1) between 2011 and 2012. Deployment...

Time series of depth data, obtained for 6 oceanic whitetip sharks (Carcharhinus longimanus) tagged with pop-up satellite archival tags, were analyzed in detail. The aim was to improve our knowledge of the vertical behavior of this species. Individuals were tagged in the Atlantic Ocean (n=5) and Indian Ocean (n=1) between 2011 and 2012. Deployment p...

We investigated the habitat utilization, vertical and horizontal behaviour of Atlantic bluefin tuna Thunnus thynnus (ABFT) in relation to oceanographic conditions in the northwestern Mediterranean Sea, based on 36 pop-up archival tags and different environmental data sets. Tags were deployed on early mature ABFT (127–255 cm) between July and Novemb...

A set of functions to generate, access and analyze standard data products from archival tagging data.

A set of functions to generate, access and analyze standard data products from archival tagging data.

A tutorial for the R-package ”oceanmap”, illustrating how to map oceanographic data within R.

Moored fish aggregating devices (MFADs) are increasingly being used in small-scale tropical fisheries to access pelagic fish species that are otherwise difficult to harvest in large numbers. Little attention has yet been paid to monitoring MFADs in coastal areas, however. This is most likely due to the small-scale nature of most fisheries that util...

Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the northwestern Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis....

A R interface to setup, run and read IRATE model runs to assess band recovery (conventional tagging) data (i.e. age-dependent or independent fishing and natural mortality rates).

Plotting toolbox for 2D oceanographic data (satellite data, sst, chla, ocean fronts & bathymetry). Recognized classes and formats include ncdf4, Raster, ’.nc’ and ’.gz’ files.

Declines in Atlantic bluefin tuna stocks (ABFT, Thunnus thynnus), due to extensive over-fishing, have been widely publicized in recent decades. To counteract this trend, regulatory measures have been introduced by the fisheries managers, aiming at the rebuilding of ABFT stocks. However, apart from difficulties in controlling the implementation of t...

Pop-up archival tags (PAT) provide summary and high-resolution time series data at predefined temporal intervals. The limited battery capabilities of PATs often restrict the transmission success and thus temporal coverage of both data products. While summary data are usually less affected by this problem, as a result of its lower size, it might be...

Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to pro...

Conservation and management measures for exploited fish species rely on our ability to monitor variations in population abundance. In the case of the eastern stock of Atlantic bluefin tuna (ABFT), recent changes in management policies have strongly affected the reliability of fishery-dependent indicators due to drastic changes in fishing season/are...

The identification of spawning sites of exploited fish stocks is particularly important for recruitment and conservation. Spawning-site fidelity has been discussed for many migratory fish species including Atlantic and Pacific herring, and might represent an important factor for the structuring of herring populations. However, identifying spawning...

Since 2000, Ifremer has conducted yearly aerial surveys during late summer-early fall on juvenile Atlantic bluefin tuna (ABFT) in the Northwestern Mediterranean in order to calculate a fishery-independent index of abundance. This scientific survey provides crucial information for stock assessment, in particular because juvenile ABFT are no longer t...

The investigation of larval dispersal and retention, their variability and dependence on wind conditions, has become a major topic in fisheries research owing to potential effects on stock recruitment and stock structuring. The present study quantifies the wind‐induced variability of larval retention of herring in a highly productive coastal lagoon...

Bauer, R. K., Gräwe, U., Stepputtis, D., Zimmermann, C., and Hammer, C. 2013. Identifying the location and importance of spawning sites of Western Baltic herring using a particle backtracking model. – ICES Journal of Marine Science, doi:10.1093/icesjms/fst163. The recruitment success of some herring stocks fluctuates strongly, and apparently, succe...

Nearshore 0-group western Baltic cod are frequently caught as bycatch in the commercial pound net fishery. Pound net fish- ermen from the Danish Isle of Funen and Lolland and the German Isle of Fehmarn have recorded their catches of small cod between September and December 2008. Abundance patterns were analysed, particularly concerning the influenc...