Quantitative description of six fish species' gut contents and prey abundances in the Baltic Sea (1968-1978)

Abstract

The dataset presents a compilation of stomach contents from six demersal fish species from two functional groups inhabiting the Baltic Sea. It includes detailed information on prey identities, body masses, and biomasses recovered from both the fish's digestive systems and their surrounding environment. Environmental parameters, such as salinity and temperature levels, have been integrated to enrich this dataset. The juxtaposition of information on prey found in stomachs and in the environment provides an opportunity to quantify trophic interactions across different environmental contexts and investigate how fish foraging behaviour adapts to changes in their environment, such as an increase in temperature. The compilation of body mass and taxonomic information for all species allows approaching these new questions using either a taxonomic (based on species identity) or functional trait (based on body mass) approach.

Fig. 1

Location of bottom trawls (lines) and bottom grab stations (numbered dots) in Kiel Bay. The red point defines the station for temperature measurements (54° 35.894 N; 11° 08.895 E). Adapted from Arntz et al. 1974.

Fig. 2

Distribution of fish analysed over the period covered by the dataset. Colours represent different fish species, and the y-axis shows the number of individuals harvested for each trawling.

Fig. 3

Number of fish sampling events. (a) per year, (b) per month, pooled across all years.

Fig. 4

Number of benthos samplings performed per year for the two stations.

Fig. 5

Entity relationship diagram representing the structure of the database. Variables in bold represent the primary keys (i.e. unique identifier for each datapoint) for each table.

Fig. 6

Correspondences between prey species observed in fish stomachs and in their corresponding environments in the full dataset (panel a) and focusing on fish for which less than 98% of prey biomass found in stomachs correspond to species also found in their environment (panel b). The x-axis represents the proportion of the prey biomass in fish stomachs that comes from species also found in the environment. A value of 1 means that all prey species found in fish stomachs were also found in the environment, and a value of 0.5 means that only 50% of the prey biomass in fish stomachs correspond to species also found in the environment.