Documenting the spatial and temporal expansion of grouper species in the eastern Adriatic Sea (Croatia) through local ecological knowledge of recreational fishermen

Abstract

Groupers are important predator marine fish species, and also economically important to commercial and recreational fisheries, but threatened by overfishing worldwide. The dusky grouper (Epinephelus marginatus) is the most common species that historically occurred in the southern and central Eastern Adriatic, while other species were mostly restricted to the southern part of the region or were not recorded in the Adriatic Sea. However, the warming of the sea caused by recent climate change has caused some grouper species in the Eastern Adriatic to expand northward. This spread has been poorly documented, largely because rocky coastal habitats, which are less accessible to conventional research methods that often rely on specific fishing gears, have received far less attention than other more accessible habitats i.e. soft bottoms. Reports of recent grouper expansion are primarily anecdotal and mainly based on the extensive observations of recreational fishermen who mainly utilize rocky coastal habitats. In order to gain insight into this phenomenon, we conducted a survey to investigate the distribution of groupers along the Croatian coast of the eastern Adriatic using the Local Ecological Knowledge methodology. Semi-structured interviews were carried out to record fishers' knowledge and perceptions of changes in their catches, as well as personal observations. The data collected provided information on the spatial and temporal expansion of groupers in the eastern Adriatic over the last 60 years, as perceived by local recreational fishermen.