Scottish seabird conservation action plan: vulnerability report

Threats To Plentiful Food Supplies

Reduction In Prey Availability

Seabird species are negatively impacted by reduced prey availability, either from lower prey density or decreased encounter rates (Mitchell et al., 2004; Cury et al., 201). Prey reduction may also arise as a result of removal and/or damage to prey supporting habitat such as sandbanks, seagrass meadows and kelp forests, rendering previously rich areas no longer suitable.

Prey reductions can lead to immediate loss of individual fitness and starvation, which can affect survival and can reduce numbers of birds attempting to breed (Springer et al., 1986). If food is scarce during the chick rearing period, breeding success can also be reduced or whole colonies may fail to produce any young. Prey availability is also constrained by seabird foraging ranges (during breeding) and dive depth, both of which vary greatly among species.

The three most important prey fish for seabirds foraging in Scottish waters are sandeel, sprat and herring (ICES., 1996). All of these, until recently, have been subject to commercial fisheries. In March 2024, fishing for sandeel was prohibited in all Scottish waters and the English part of the North Sea. It is anticipated as a result, that sandeel stocks will increase. Sprat and herring fisheries are focused on areas supporting the highest densities of fish, for sprat this is the southern North Sea, for herring, fisheries in recent years include locations such as the Firth of Forth, Moray Firth and the Clyde (Aires et al., 2014).